# open source hub motor/wheel motor



## unclematt (May 11, 2008)

Hi All,
There was another thread where we have discussed the need for an open source wheel motor. The wheel motors that are currently in the media are not available to the public unless you want to spend obscene amounts of money, if even then. So I think it would be great for all of us to collaborate on creating an open source set of plans to enable EVers to create their own wheel motors.

So lets start the show:

1) We need a list of objectives to meet with our wheel motor.

2) We need sources for raw materials and components.

3) We also need to find or design controllers to run our wheel motor.

So please offer links and expertise to accomplish this.

I personally think we need a brushless motor, and it needs to put out at least 40kW of power. It also needs regenerative capability, and if possible I would like to do away with friction brakes entirely.

Let the creativity begin!

:-D


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## JRK5150 (May 18, 2008)

I agree, open source is the best way to go for us all! Designing wheel motors should be fairly straight forward. The real issue is in designing an appropriate controller that can act as a controller as well as keeping all of the motors moving EXACTLY in accordance with the others. I suggest we expand this to an open source wheel motor drive system with emphasis on a safe controller. Since we would be designing a controller from scratch anyway, I feel AC would meet the goals better than DC. With AC we could have a brushless system with regenerative braking, ABS, traction control and it would be more efficient. May I further suggest that we focus on writing the control program first (test it with existing hardware), then focus on building our open source hardware. I think this is a great idea and would like to help out any way I can!

-John


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## CNCRouterman (May 5, 2008)

I like the open source concept, though I think making it more universal is more appealing. 
Wheel Hub motors are, by definition, in the wheel... So, that would mean that the weight of the wheel will be greater than a conventional wheel design. The higher the capacity of the motor, the more it is likely to weigh.

Given the above, a wheel hub motor would seem more applicable to low speed use, or applications where suspensions are a secondary consideration, due to the inherently higher un-sprung weight.

I agree than defining the objectives of the motor are important at the start.

I think a wheel hub motor would be well suited for applications such as garden tractors, material haulers, electric mule, forklift, etc. 40kw would be overkill for most of these applications. However, I have read on the website of one manufacturer of wheel hub motors, that they can be mounted inboard of the wheel, and couple to the wheel though a drive axle (one motor, one wheel). That makes sense to me in terms of keeping unsprung weight down, even using one to drive a conventional auto RWD axle, keeping the differential, or two for 4WD.

I suggest keeping conventional mechanical brakes because at some rpm point, it will take energy to slow it anymore, and it will definitely require energy to hold position against an outside load, so for full stop or parking, conventional brake are hard to beat.

With regards to the controller. I am very interested in learning more about design and building a controller for my future EV project. I have found that there are many electrical CAD packages out there, I found one called Dipfree 1.5 which has a freeware version. As I am pretty ignorant about integrated circuits at this point, I don't know if it will help in design and understanding. I am quite familiar with CAD/CAM software for use in CNC routing, so I know that mere possession of a tool does not equate to proficiency with the tool. I do hope, however, that possession of this electric design tool will help me learn. I have been watching another thread on this board regarding an AC 3 phase controller, but it is still mostly over my head technically.


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## thesilverring (May 25, 2008)

Does anybody have an IEEE membership? If so you could view this article. I actually went to Bath Uni and went to this guy's lectures - but at the time I was not so interested. Going to uni when you are 18 years old to actually learn the material in a degree course is not the best idea. 

This is the sort of thing you are talking about right?
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=497248&isnumber=10700

A couple of the guys working on this stuff were decent chaps - Prof Dave Rodger (Scottish guy who looks more like Billy Connolly than Billy Connolly). Paul (?) Leonard and some other chap who's name escapes me right now. Anyway, they developed some Finite Element Analysis software to model electro-magnetics - specifically for motors. 

About all I remember from the Motor design courses are Gaussian beer cans, the model Doc Rogers used to teach field theory.


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## Manntis (May 22, 2008)

thesilverring said:


> Does anybody have an IEEE membership? If so you could view this article. I actually went to Bath Uni and went to this guy's lectures - but at the time I was not so interested. Going to uni when you are 18 years old to actually learn the material in a degree course is not the best idea.
> 
> This is the sort of thing you are talking about right?
> http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=497248&isnumber=10700


Good lead - and an interesting paper  Unfortunately such an axial flux motor, IMHO, adds sprung weight in the form of the greater diameter of fixed magnets and the diagrams seem to underestimate the amount of travel required by the rotating mass in suspension compression and suspension extension conditions. Covering the complete range of motion would necessitate placing the bottom of the (rather expensive) magnet housing assembly very close to the road and because of its hard mounting position it would not be able to softly deflect from road debris encountered while in suspension compression. The potential for damage could be very high indeed.


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## unclematt (May 11, 2008)

So how will we decide which basic design is best to follow? What power output is being targeted would be good to figure out as well.

If people could do a mini-presentation on the design they are promoting, that would help the rest of us get up to speed on their proposal. Links to photos/articles and text should do fine.

Question: should the controller be able to fit in the stator of the motor? If space is left for this in the center of the motor, will that cause problem with flux distribution or saturation?

Some informative links:

http://groups.yahoo.com/group/lrk-torquemax/

http://www.wavecrestlabs.com/automotive-products-wheelmotor.php

http://www.youtube.com/watch?v=8tLQ2-yKT4Y


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## judebert (Apr 16, 2008)

I always thought it would be interesting to put magnets in the rotor, and outfit the calipers with windings. You could get propulsion, regen, and friction braking all in the same place.


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## Manntis (May 22, 2008)

judebert said:


> I always thought it would be interesting to put magnets in the rotor, and outfit the calipers with windings. You could get propulsion, regen, and friction braking all in the same place.


brake dust would be a problem, as would rotor wear and the necessity of keeping the rotors in an open airstream for cooling.

Easier to make a conventional wheel motor with a separate brake rotor for mechanical braking. Or make the rim itself the motor spinning on a fixed hub.


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## John (Sep 11, 2007)

The hub/wheel motor would be very difficult to do and do right. Getting it to fit with suspension and brakes would possibly require adaption of those designs as well as the wheel and motor. Each different vehicle it was adapted to would require a redesign. While the hub motor fits with the ideal of minimum mechanical complexity it doesn't fit with other ideals such as minimising unsprung weight. It will also change the dive/rise characteristic of the suspension geometry by applying the motor torque to the suspension rather than the vehicle body, and require building the motor to with stand high shock loading while being light weight. For a retro fit conversion unit I think a dual motor direct drive diff replacement for an AWD donor vehicle would be easier to achieve and wouldn't have the unsprung weight issue. An electrically commutated permanent magnet brushless DC outrunner with a large number of poles would be the configuration I would choose. The permanent magnets (on the rotor) would be arranged in a halbach array to minimise external magnetism, intensify internal flux density, and negate the flux ring. I wonder if an iron less core would be feasible to prevent cogging. Would this make the motor more or less efficient?


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## JRK5150 (May 18, 2008)

I think we should first look at the current cutting edge of technology in wheel motor design. If you don't already know about PML and their Hi-Pa drive wheel motors, check them out here.http://www.pmlflightlink.com/motors/hipa_drive.html

Next, I think we should make sure that we do NOT infringe on any patents. To this end, I suggest keeping this as simple as possible. We can get fancy later. Getting sued developing a free drive system would severely suck!

For simplicities sake, we should probably decide on a standard size and basic mounting bracket arrangement. I think unclematt's suggestion of 40kws per motor seems about right. 

On the topic of controller design, I suggest we split duties between a main controller and separate wheel controllers.
-The main controller would rectify dc to ac (vice versa for regen. braking) and send basic commands to the wheels.
-The wheel motor controllers would determine the final frequency and amplitude. 

The driver input, ie. throttle control, steering, braking, would go to the main controller which would send out the basic signal to the wheel motor controllers. The wheel motor controller would take the main signal and modify it based on input it gathers from it's wheel and the other wheels on the vehicle. 

Finally, what sort of open source programs are currently available to accomplish our goal? And, what sort of hardware would we run it on?

Well, what do you think about this for nailing down the basics?


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## John (Sep 11, 2007)

This could be very cool. Independent torque controlled high powered all wheel drive and extreme mechanical simplicity. It could be a huge leap forward in terms of vehicle dynamics. It could do full regen with proper brake bias not just fore and aft but also left and right if braking while cornering. It could do active yaw control with the drive assisting the turning of the vehicle possibly even using a combination of regenerative braking and drive on the inside and outside wheels to aid vehicle turning. The computer could dial down the torque to any wheel when excessive slip is detected. All manner of new things could be done that aren't currently possible with today’s cars. It could put the electric car firmly out in front in terms of drivability and nimbleness and surefooted safety.


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## JRK5150 (May 18, 2008)

Yeah, this is cool! Traditionally, converting a car to electricity has been a bit of a compromise, but this could actually make the cars perform better in every way. Also, with no engine or transmission, vehicles will be left with a large, empty engine bay that could be filled with a generator... extra batteries... fuel cell... the options are endless!


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## mattW (Sep 14, 2007)

It would also make a conversion to a series hybrid ridiculously easy. Just swap the wheels and add a battery pack/controller while keeping the existing engine (or downgrading the size). It could be fitted pretty easily to just about any vehicle with the space for batteries.

The only problem would be designing the motors for such low rpm and sensing/controlling the 4 wheels at once.


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## Dennis (Feb 25, 2008)

To make such a motor you would need the following:



Vacuum Pressure Impregnation System (VPI)


Oven


High temp Resin


Metal press with dies needed to cut out the stator and rotor steel sheet laminates


Thin steel sheets on large rolls


Enamel coated copper wire


Furnace for melting copper or Aluminum


Special metal casting machine to cast the rotor bars of either aluminum or Copper into the rotor...


Nomex paper


Coil winding machine (unless you want to do it by hand)


Induction heating device to heat the inner race of the bearings such that it expands to fit over shafts.


Test equipment such as insulation testers...

This undertaking is not exactly what I call easy. Maybe you can outsource the rotor design and stator design? 



*
*


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## JRK5150 (May 18, 2008)

Anyone else in the central Florida area? I think I'd like to start developing this into a working concept. I don't have a problem with fabrication, so my plan is to get a small, fairly aerodynamic piece of junk and mount conventional AC motors at each wheel. We could use this to develop the controller setup. After we have the controller designed and programmed, we could post free plans and software online for everyone to use. Then we could work on developing the actual motor. I'm looking around locally as well, to try and find others to help.


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## JRK5150 (May 18, 2008)

Would developing this in stages be the best idea? Rather than jumping head first into the entire project with all of it's complexities, maybe the best idea would be to break it down into steps. 
For instance, step one could be to mount two conventional AC motors to the rear wheels of a front wheel drive car. This could be used to develop the control system without the extra complexity of four wheels or the need for complex algorithms for steering wheel motors. It would allow for the main controller to be developed as well as the basic programing for the wheel motor controller. 
Step two could be designing and building the actual wheel motors. With the basic control system in place and wheel motors built, we would have a simple 2wd conversion for light cars. This would also be nearly a bolt on hybrid setup for most front wheel drive cars. 
Step three could be to add the front wheel motors and work out the added complexities of four motors working together as well as steering inputs. This would open the door for heavier, all electric conversions as well as true hybridization. 
This seems to be the quickest way to having this technology on our cars. Does this make sense or am I just over thinking it?


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## Wirecutter (Jul 26, 2007)

mattW said:


> The only problem would be designing the motors for such low rpm and sensing/controlling the 4 wheels at once.


 I have to agree with Manntis about the unsprung weight issue. A wheel-hub motor would be fine for something like a forklift or some kind of industrial vehicle where weight isn't as much an issue, and the "road" surface is very smooth. What I always thought of when I considered a "4 wheel - 4 motor" vehicle is having the motors mounted inboard and shafted to the wheels.

Back to mattw's comment, though - I read that this sensing and controlling of motor speed is one of the things that makes the Wrightspeed X1 so stinkin' fast. The AC Propulsion controller used in the X1 is modified to provide traction control. It will sense wheel speed of the driven _and_ undriven wheels, and allow the driven wheels to spin only slightly faster than the undriven wheels. The effects of limiting the amount of slip allowed between the tire and the road surface is already well proven with ABS. I would imagine the algorithm gets slightly more complicated when dealing with turning and attempting to power slide, because at such times, front and rear wheels need to turn at different speeds. But I would also imagine that the performance of such a car would feel absolutely marvelous. 

Ok, well it's a cool idea, but I admit a little problematic for a vehicle with all wheels being driven. You'd have to come up with another way of measuring the ground speed of the vehicle.

-Mark


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## mattW (Sep 14, 2007)

Have you guys seen this:
Siemens VDO eCorner Project
That wheel does just about everything!


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## unclematt (May 11, 2008)

Wirecutter said:


> I have to agree with Manntis about the unsprung weight issue. A wheel-hub motor would be fine for something like a forklift or some kind of industrial vehicle where weight isn't as much an issue, and the "road" surface is very smooth. What I always thought of when I considered a "4 wheel - 4 motor" vehicle is having the motors mounted inboard and shafted to the wheels.
> 
> Back to mattw's comment, though - I read that this sensing and controlling of motor speed is one of the things that makes the Wrightspeed X1 so stinkin' fast. The AC Propulsion controller used in the X1 is modified to provide traction control. It will sense wheel speed of the driven _and_ undriven wheels, and allow the driven wheels to spin only slightly faster than the undriven wheels. The effects of limiting the amount of slip allowed between the tire and the road surface is already well proven with ABS. I would imagine the algorithm gets slightly more complicated when dealing with turning and attempting to power slide, because at such times, front and rear wheels need to turn at different speeds. But I would also imagine that the performance of such a car would feel absolutely marvelous.
> 
> ...


The whole "unsprung weight" issue is overblown in my opinion. Yes, we should design them as light as possible, but in my research I have found that most manufacturers found that when much of the weight is removed that is associated with the regualr drivetrain that the wheel motor ends up weighing only slightly more by comparison. I am NOT interested in mounting motors to shafts. That defeats part of the purpose of doing wheel motors in the first place.


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## unclematt (May 11, 2008)

mattW said:


> Have you guys seen this:
> Siemens VDO eCorner Project
> That wheel does just about everything!


 
Their concept is a good one, but they still use friction brakes, which is unneccesary and weighty. They also do not offer them to the public at any price, so they are vaporware for the moment.


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## mattW (Sep 14, 2007)

You will need friction brakes on at least 2 wheels. Regen isn't very effective at low rpm and not at all when parked.


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## unclematt (May 11, 2008)

mattW said:


> You will need friction brakes on at least 2 wheels. Regen isn't very effective at low rpm and not at all when parked.


Thats not what PML Flightlink is reporting they found in their wheel motor development. They use ZERO friction brakes, and have zero problems. You can find this on their site being used on their mini-cooper, and also the Lightning is being sold in Britain using their wheel motors, which have no friction brakes whatsoever.


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## mattW (Sep 14, 2007)

Wow that's pretty impressive. I was just linking them for a concept not to buy them, I'd be pretty impressed if this idea gets off the ground i.e. the open source version.


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## unclematt (May 11, 2008)

mattW said:


> Wow that's pretty impressive. I was just linking them for a concept not to buy them, I'd be pretty impressed if this idea gets off the ground i.e. the open source version.


Their concept is brilliant, I agree. And you may be correct that we have to use them in an open source design. Only time will tell how successful this project will be, or if we will come to the conclusion that friction brakes are required (maybe even as a parking /emergency brake).


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## JRK5150 (May 18, 2008)

The debate on brakes with this project is valid for both sides. I see pure electric regen. brakes as fine for all but stopping, parking, and possibly extremely low speed. The simplest solution I can come up with is to incorporate provisions for mounting a small mechanical braking system into the design of the wheel motor. This way, brakes could be added to the rear wheels for stopping and parking while using electric brakes to handle the rest. The problem with allowing the electric brakes to hold the car when stopped or parked, which they could theoretically do, is that the motors would be taking power even when not in motion. It seems to me that the minuscule weight gain of two small discs or drums would out-weigh the power losses of parked electric brakes in the long run. The front brakes wouldn't need any sort of mechanical brakes though!


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## mattW (Sep 14, 2007)

I just had a thought that we could put 'skid steer' as one of the options for the controller i.e. right hand side wheels to move forward and left hand to move back. Then you can turn on less than a dime just like a tank... lol wouldn't do the tyres much good but would be amazing on narrow streets for U turns!


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## JRK5150 (May 18, 2008)

HA! What the heck! As long as it was a programming option, some folks might find it useful!


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## Manntis (May 22, 2008)

unclematt said:


> The whole "unsprung weight" issue is overblown in my opinion. Yes, we should design them as light as possible, but in my research I have found that most manufacturers found that when much of the weight is removed that is associated with the regualr drivetrain that the wheel motor ends up weighing only slightly more by comparison. I am NOT interested in mounting motors to shafts. That defeats part of the purpose of doing wheel motors in the first place.


The regular drivetrain weight isn't unsprung weight, it's weight suspended. Unsprung weight refers specifically to the weight of items _not_ suspended, i.e. the wheel rims, tires, hubs, and brakes (with the exception of inboard IRS systems such as Jaguar's original disc configuration)

Using a wheel motor is an increase in unsprung weight. Removing the stock ICE, transmission, radiator, etc. is removing sprung weight. Two different things when it comes to the physics of how various bits of the vehicle move in relation to each other.


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## JRK5150 (May 18, 2008)

While it is true that removing the engine and transmission will not effect the unsprung weight, electric wheel motors can eliminate the need for lots of other weighty pieces. On most rear wheel drive vehicles, the weight of the entire differential/rear end housing is unsprung. So is the braking assembly and half the weight of the drive shaft and half the weight of any control arms. This alone could more than offset the weight of a properly designed wheel motor. For front wheel drive and IRS equipped vehicles, the brake assemblies, hub/steering knuckle assemblies, and half the weight of the half shafts could either be eliminated or drastically reduced in size and weight depending on the design of the wheel motor. Here again, the unsprung weight issue isn't problematic as long as the design of the wheel motor is kept as light as possible. The biggest problem I see is in the front suspensions of rear wheel drive vehicles or the rear suspensions of front wheel drive vehicles. Here, the only weight to be eliminated would typically be the knuckle/hub assembly and some brake components. Even in this case, though, the weight increase of a wheel motor over the removed components would be minimal as far as I can tell. I think it would be possible to all but eliminate any minor weight gain by using a lighter weight aftermarket wheel and tire combination. I think, through proper engineering, the unsprung weight debate will be a virtual non-issue.


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## unclematt (May 11, 2008)

mattW said:


> I just had a thought that we could put 'skid steer' as one of the options for the controller i.e. right hand side wheels to move forward and left hand to move back. Then you can turn on less than a dime just like a tank... lol wouldn't do the tyres much good but would be amazing on narrow streets for U turns!


This would make parking much easier as well...

On the subject of motor form, we have a suggestion of an AC induction motor, and I wonder about a large brushless DC motor. Maybe we should discuss and toss around the benefits and drawbacks to both. Then we can start to talk about motor construction.

On the controller and software front, I must admit I have less expertise in this are than any other. I liked the suggestion made about a test bed that was simple and easy to build to test our prototype controllers. Is someone willing to take on this part of the project and run with it as a general coordinator/facilitator?


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## JRK5150 (May 18, 2008)

I would love to take on the test bed build if that would be ok! I'll look locally to see what donor vehicles are around for cheap. I was thinking some small front wheel drive car. What do you think would be best? Anyone on here live near me in central Florida?


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## mattW (Sep 14, 2007)

Do we actually have anyone on this site who can build/commission the build of these motors? If so you would assume they would be the one with the prototype as they can make changes when needed while the rest of the team works on the design stuff.


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## unclematt (May 11, 2008)

Manntis said:


> The regular drivetrain weight isn't unsprung weight, it's weight suspended. Unsprung weight refers specifically to the weight of items _not_ suspended, i.e. the wheel rims, tires, hubs, and brakes (with the exception of inboard IRS systems such as Jaguar's original disc configuration)
> 
> Using a wheel motor is an increase in unsprung weight. Removing the stock ICE, transmission, radiator, etc. is removing sprung weight. Two different things when it comes to the physics of how various bits of the vehicle move in relation to each other.


I mispoke, and should have said "regular unsprung weight", not "regular drivetrain". What you say is correct, but my point remains valid. The amount of weight removed from the wheel hub is substantial if you forego friction brakes (and other parts) as PML Flightlink has done in their design. I believe they ended up with an increase in unsprung weight of only a few kilos per tire, and report NO decreased performance or other issues with the system.


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## Manntis (May 22, 2008)

unclematt said:


> I mispoke, and should have said "regular unsprung weight", not "regular drivetrain". What you say is correct, but my point remains valid. The amount of weight removed from the wheel hub is substantial if you forego friction brakes (and other parts) as PML Flightlink has done in their design. I believe they ended up with an increase in unsprung weight of only a few kilos per tire, and report NO decreased performance or other issues with the system.


That's right - they don't report a rather key point: that there is no mechanical braking system, meaning no brakes in the event of power failure (or parking) 

Their packaging is very cool - their pricing and lack of mechanical brakes, not so much. While we debate the high cost of batteries and the ultracaps made of unobtanium promoted by EEStor and others, we overlook things like wheel motors currently selling for as much as a car, nevermind the additional energy storage component costs.

Just as Jaguar eventually moved their inboard disc brakes to the wheels, I think it's possible to develop high efficiency, compact pancake motors as one step, then, with reasonably priced and working units with controllers, evolve the packaging to function in the hubs with proper brakes included. 

Actually Hydro Quebec's spin-off company TM4 claims they have a working system with integrated drum brakes that might work on smaller vehicles, saving discs for the front brakes as many production cars still do. I'd be concerned about the heat generated by the drums being so close to the electrics, though . Well, that and the fact that TM4 has a habit of announcing 'production ready' motors, hybrid generator-motors, and batteries that fail to materialize.


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## mjcrow (Jan 5, 2008)

The CSIRO build a nice (but expensive) in wheel unit (Brushless DC for Solar racing cars), some of the information they provide in the links below may be helpful in terms of design concepts.

General Overview :- http://www.csiro.au/solutions/psz7.html

Technical Details :- http://www.csiro.au/resources/pf11g.html

The conference paper is good for understanding the decision processes involved in developing something like this. 

This is a 6kg unit developing 1800W, to build something capable of driving an ev the unit would have to be quite a bit larger and hence heavier. Perhaps the idea of motors that could be mounted inboard to start with has merit, and later with more development perhaps making it possible to mount them in the hub/wheel.


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## mattW (Sep 14, 2007)

I love that solar cars can travel 110+ km/h on just 1.8kW and sunlight... we'd be lucky to get ten times that efficiency!


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## unclematt (May 11, 2008)

JRK5150 said:


> While it is true that removing the engine and transmission will not effect the unsprung weight, electric wheel motors can eliminate the need for lots of other weighty pieces. On most rear wheel drive vehicles, the weight of the entire differential/rear end housing is unsprung. So is the braking assembly and half the weight of the drive shaft and half the weight of any control arms. This alone could more than offset the weight of a properly designed wheel motor. For front wheel drive and IRS equipped vehicles, the brake assemblies, hub/steering knuckle assemblies, and half the weight of the half shafts could either be eliminated or drastically reduced in size and weight depending on the design of the wheel motor. Here again, the unsprung weight issue isn't problematic as long as the design of the wheel motor is kept as light as possible. The biggest problem I see is in the front suspensions of rear wheel drive vehicles or the rear suspensions of front wheel drive vehicles. Here, the only weight to be eliminated would typically be the knuckle/hub assembly and some brake components. Even in this case, though, the weight increase of a wheel motor over the removed components would be minimal as far as I can tell. I think it would be possible to all but eliminate any minor weight gain by using a lighter weight aftermarket wheel and tire combination. I think, through proper engineering, the unsprung weight debate will be a virtual non-issue.


I agree with your analysis and conclusion!


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## Manntis (May 22, 2008)

unclematt said:


> I agree with your analysis and conclusion!


Eliminating the weight if the driveshaft, axle, and differential of a RWD live axle car is a fair argument. However, wheel motors are extremely parts-dense and are surprisingly heavy for their size, much like the 'keg' of a rotary engine is heavier than the short block of a piston engine of similar dimensions. 

There's also the consideration of the vibrations inherent in bouncing the motors up and down over bumps vs. the relatively dampened mounting of motors suspended inboard. The lightest (and weakest) of the PML Flightlink wheel motors, which are among the most compact on the market, are 18kg. That's almost 40lbs per wheel vibrating over every bump on the road, outboard of the spring fulcrum. Add in the water splash hazard, dust and FOD hazard, etc. and the already expensive wheel motors could become even more expensive to maintain when compared to inboard motors.

That said, if a person or company finds a way to solve these problems I'll be among his, her, or its strongest supporters. The parts reduction and packaging possibilities offered by wheel motors are so amazingly elegant it's definitely a worthy goal.


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## unclematt (May 11, 2008)

JRK5150 said:


> Since we would be designing a controller from scratch anyway, I feel AC would meet the goals better than DC. With AC we could have a brushless system with regenerative braking, ABS, traction control and it would be more efficient.
> -John


Hey John,
When you wrote this, were you thinking of AC at 60kHz, or DC delivered in an alternating way with a controller (brushless DC motor) ? Or exactly what?
If you have any diagrams or links, please post. thanks.


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## unclematt (May 11, 2008)

Manntis said:


> Eliminating the weight if the driveshaft, axle, and differential of a RWD live axle car is a fair argument. However, wheel motors are extremely parts-dense and are surprisingly heavy for their size, much like the 'keg' of a rotary engine is heavier than the short block of a piston engine of similar dimensions.
> 
> There's also the consideration of the vibrations inherent in bouncing the motors up and down over bumps vs. the relatively dampened mounting of motors suspended inboard. The lightest (and weakest) of the PML Flightlink wheel motors, which are among the most compact on the market, are 18kg. That's almost 40lbs per wheel vibrating over every bump on the road, outboard of the spring fulcrum. Add in the water splash hazard, dust and FOD hazard, etc. and the already expensive wheel motors could become even more expensive to maintain when compared to inboard motors.
> 
> That said, if a person or company finds a way to solve these problems I'll be among his, her, or its strongest supporters. The parts reduction and packaging possibilities offered by wheel motors are so amazingly elegant it's definitely a worthy goal.


While researching this technology, I had the same concerns, but found that they have not stood in the way of several companies producing designs that function as desired and deliver power and efficiency at the same time.

I encourage those that doubt to take a look at what is online at PML Flightlink, and this site:

http://www.e-traction.com/TheWheel.htm

and any number of other sites that can be found on google using "wheel motor" or "hub motor" as search terms. Many of your questions and concerns can be put to rest with a review of the available material.


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## unclematt (May 11, 2008)

Here is some info on the BluWave system​ 

46 kW Hub Motor ​ 
BluW
āv Systems has developed a 46 kW peak in-wheel hub motor for automotive, commercial, and military vehicle applications. The motor was designed to package into a 17" rim and integrates the hub (and wheel bearings), a disk brake, and motor into a compact, powerful, unit. Four of these motors, one in each wheel of a four-wheeled vehicle, are capable of propelling a medium-sized automotive vehicle up to 90 mph and up a 30% grade. The motors also provide regenerative braking for increased vehicle range, shorter stopping distances, and reduced brake wear. ​ 
The motor is a brushless DC, permanent magnet with an integrated gear set, hub, and brake. The power electronics are IGBT-based with an integrated DSP for motor control. The control electronics can communicate with CAN including J1939 as well as RS-232 and RS-485 protocols. ​It can be used as the primary drive in battery-electric or series-hybrid vehicles or as a supplemental drive in a parallel hybrid architecture, providing independent wheel control for all-wheel drive functionality as well as steering assistance and stability enhancement. For automotive, the use of these motors can free up valuable package space in the middle of the vehicle that can be used for additional passenger or storage space. 

​
Peak Power @ 2900 motor rpm 46kW ​ 
Continuous Power at 1300 motor rpm 20kW 

Peak Torque @ 900 motor rpm 

1100 (at wheel)Nm ​ 

Continuoss Torque 620 (at wheel)Nm ​ 

Speed Range 0-900 reversible (at wheel)rpm ​ 

Nominal Bus Voltage 316 VDC ​Peak Bus Current 300 A
Peak Efficiency  > 95% ​Mechanical: ‡ 
Gearing ~ 4:1 
Radial Load, static 750kg 
Radial Load, dynamic 6,600kg 
Axial load 640kg 
Motor Outside Diameter 350mm 
Motor Width (Motor Only) 180mm 
Motor Weight  45kg 
Noise < 55dB 
Motor – Suspension Interface Knuckle Mounted ​


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## Dunkard (Jun 1, 2008)

What I would suggest is not a wheel motor, but rather, a motor not shaped to fit in a wheel - one of a smaller diameter and wider, but made to operate at wheel RPM, so it can be connected directly to a set of CV axles typical of FWD's and RWD's with independent rear suspensions like the Corvette. Obviously unsprung weight would be just as good as existing cars going that route. I own a Nissan 240SX with RWD and an independent rear suspension, and it most certainly rides and handles better than an old Firebird or Trans AM with their unsprung differentials and heavy axle housing. I seriously doubt that a wheel motor would not increase unsprung weight, and I doubt that subjecting the motor to the violent shaking of a wheel is a good idea. BUT, operating an inboard motor at wheel RPM with no gears at all would surely boost efficiency.

To further reduce unsprung weight below that of existing cars, there's a concept I saw back in the sixties on an Italian car which had "inboard brakes" on the rear wheels. The rear brakes were mounted near the center of the car, on the inside end of the CV axles, near the differential, which of course was sprung. Perhaps what we should build is a direct drive "wheel RPM" motor built with friction brakes already on it, or in it, and keep the CV axles. The friction brakes, being built right onto the motor, would be better suited to integrating into an anti-lock brake system controlled by the motor controller. And on RWD's, CV axles don't reduce efficiency at all because they're almost always held in a nearly straight position, and your power isn't being bent around a turn.


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## Manntis (May 22, 2008)

Dunkard said:


> To further reduce unsprung weight below that of existing cars, there's a concept I saw back in the sixties on an Italian car which had "inboard brakes" on the rear wheels. The rear brakes were mounted near the center of the car, on the inside end of the CV axles, near the differential, which of course was sprung. Perhaps what we should build is a direct drive "wheel RPM" motor built with friction brakes already on it, or in it, and keep the CV axles. The friction brakes, being built right onto the motor, would be better suited to integrating into an anti-lock brake system controlled by the motor controller. And on RWD's, CV axles don't reduce efficiency at all because they're almost always held in a nearly straight position, and your power isn't being bent around a turn.


What you describe is the original Jaguar IRS disc brake system. IIRC Jaguar was the first to use disc brakes on cars, borrowing the idea from aircraft, and mounted the rear ones inboard specifically to reduce unsprung weight. Because of the superior anti-fade characteristics of a disc brake v. a drum brake, this gave them a huge advantage on the racing circuit.

Many hotrodders buy Jaguar type IRS systems premade to install in the back of their one-off cars.

However, Jaguar evolved away from inboard brake setup because it made checking and changing the pads, or removing rotors for turning, a major affair as opposed to the easy access and brake disc cooling provided by simply mounting the brakes on the hub.


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## Dunkard (Jun 1, 2008)

Manntis said:


> However, Jaguar evolved away from inboard brake setup because it made checking and changing the pads, or removing rotors for turning, a major affair as opposed to the easy access and brake disc cooling provided by simply mounting the brakes on the hub.


You're right. I didn't think about the maintenance pain that must have been. But on the other hand, If we're talking about using the friction brakes in combination with regen braking in the motor, that would greatly reduce the amount of maintenance attention that the brakes would need, possibly offsetting the extra trouble.


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## Manntis (May 22, 2008)

Dunkard said:


> You're right. I didn't think about the maintenance pain that must have been. But on the other hand, If we're talking about using the friction brakes in combination with regen braking in the motor, that would greatly reduce the amount of maintenance attention that the brakes would need, possibly offsetting the extra trouble.


Yes and no. In theory it should extend pad life, just as downshift slowing does, but whether you have to service your brakes every 2.5 years or every 5 years (I grabbed those numbers out of the sky for example purposes) a PITA task is still a PITA task. 

There are also mechanical advantages to mounting the discs at the hub as opposed to inboard, as your braking is immediate rather than having to be transferred through the rear axle shaft material. Having to torque a long rod to apply braking force is less desirable than slowing the hub directly.

The reverse is true of hub motors but braking _now_ as opposed to acceleration _now_ without a torque delay makes more sense from a safety standpoint. With EV conversions braking the mass of the vehicle should be one of the first things considered, though many people seem to leave that to the last.


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## unclematt (May 11, 2008)

Obviously, there are many challenges to building a practical wheel motor that is light, powerful, affordable, and can survive the driving environment. Plain and simple, it may not be do-able by a bunch of people on a message board.

I thought it would be worth a shot to at least attempt. I haven't seen any arguments yet that haven't been dealt with by current technologies, but it would be wise for us to determine whether or not this technology is within our reach. I personally think it is, given the right group of people working at it in an organized way toward practical objectives.

So how powerful should our motor be?

Should it use AC, DC, or VDC?

Should it be brushless or commutated?

Should it be a PM motor, or a series wound motor?

We also need to remember that our setup will have to be attached to the vehicle's suspension system through suspension control arms. Should we just use simple ball-joints at the top and bottom comtrol arm attachment points on the back of the stator? Don't forget we also need a steering system attachment point for front wheels (assuming we aren't using electric steering).


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## Manntis (May 22, 2008)

electric steering still requires steering arms - the rack is moved by electric rather than hydraulic assist.


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## unclematt (May 11, 2008)

Manntis said:


> electric steering still requires steering arms - the rack is moved by electric rather than hydraulic assist.


Actually, the e-corner system does not use an electric rack for steering, and instead includes the steering mechanism in the hub itself. Thus my question...


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## Manntis (May 22, 2008)

unclematt said:


> Actually, the e-corner system does not use an electric rack for steering, and instead includes the steering mechanism in the hub itself. Thus my question...


Ah, I see. The Siemens e-Corner is still in development, though, whereas production electric steering used by Delphi and others does require a rack; hence the confusion.


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## John (Sep 11, 2007)

The thing that concerns me about the notion of a regenerative only braking system is the staggering instantaneous power that can be generated or rather that the braking system is required to absorb. Say a car weighs 1500 kg (3306 lb) and is travelling at its top speed of 208 km/h (130 mph, 57.778 m/s) and can achieve 1.3g deceleration.

The derivation;
Work = Force x Distance, Power = Work/Time
so Power = Force x Distance/Time and Distance/Time is speed
This will give the instantaneous power for a given speed and decelerative force.
Power (W) = 1500 kg x 9.81 N/kg x 1.3 g x 57.778 m/s = 1105260 W = 1.105 mW
(People familiar with SI units will recognise 9.81 N/kg as the force generated by gravity on a mass).

That’s right!. Over a megawatt of power ramping down to zero at zero velocity. At this sort of deceleration the car would come to a halt in a little over 4.5 seconds so the total energy absorbed isn't that great. About 695 Wh.


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## aeroscott (Jan 5, 2008)

a meg that's huge but any motor can absorb that provided its a short period, 600 + watts hours will take me 2 to 3 miles down the road .thanks for putting the numbers together ,great and important work .


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## Manntis (May 22, 2008)

John said:


> The thing that concerns me about the notion of a regenerative only braking system is the staggering instantaneous power that can be generated or rather that the braking system is required to absorb. Say a car weighs 1500 kg (3306 lb) and is travelling at its top speed of 208 km/h (130 mph, 57.778 m/s) and can achieve 1.3g deceleration.
> 
> The derivation;
> Work = Force x Distance, Power = Work/Time
> ...


In many regen systems the regen is activated by lifting off the throttle, creating generating drag similar to engine drag when downshifting. The brake pedal provides mechanical braking only.

This of course pertains to conversions. I'm not yet certain how production cars using regen get around the ABS problem.


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## Madmac (Mar 14, 2008)

"The thing that concerns me about the notion of a regenerative only braking system is the staggering instantaneous power that can be generated or rather that the braking system is required to absorb."

The regen system has to cope with the time that the batteries are fully charged. The easy solution is not to charge the batteries fully so that under typical conditions regen can top up the batteries and not overcharge. This would have to protect against worst case of leaving home after a full charge and driving off down hill for several miles. The down side is loss of range.

Best solution is load resistors that dissipate the breaking energy as heat when it is not required. It also allows better control of the charge into the batteries. Getting rid of lots of power this way is not difficult..... electric trains aid braking the same way.

Madmac


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## John (Sep 11, 2007)

Madmac said:


> The regen system has to cope with the time that the batteries are fully charged. The easy solution is not to charge the batteries fully so that under typical conditions regen can top up the batteries and not overcharge. This would have to protect against worst case of leaving home after a full charge and driving off down hill for several miles. The down side is loss of range.
> Best solution is load resistors that dissipate the breaking energy as heat when it is not required. It also allows better control of the charge into the batteries. Getting rid of lots of power this way is not difficult..... electric trains aid braking the same way.


Would a bank of super capacitors be even better? With a 255V (Tesla voltage) system 1.1mW would produce 2550A. Doesn't seem too out there. 

As for starting on a hill, potential energy I think equals mass times gravity times height so if you knew the height of the hill you could work out how much energy would be released by the descent and subtract some for the loses. Say for example a 1000m (3280ft) hill. PE = mass(kg) x gravity(9.81N/kg) x height(m) = 1500 x 9.81 x 1000 = 14715000 Joules. One Joule equals 1 watt-second so to convert Joules to Wh's divide by 3600 so descent will release 4088 Wh. Even with a 30% grade the distance travelled would be about 3.5 km. At 100km/h my car consumes about 12kW which over this distance would equate to about 420Wh leaving about 3.67kWh to deal with. Also to attain 100km/h some potential energy would be converted to Kinetic energy in this instance about 161Wh leaving 3.51kWh.


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## reality_bytes (Jun 5, 2008)

JRK5150 said:


> While it is true that removing the engine and transmission will not effect the unsprung weight, electric wheel motors can eliminate the need for lots of other weighty pieces. On most rear wheel drive vehicles, the weight of the entire differential/rear end housing is unsprung. So is the braking assembly and half the weight of the drive shaft and half the weight of any control arms. This alone could more than offset the weight of a properly designed wheel motor. For front wheel drive and IRS equipped vehicles, the brake assemblies, hub/steering knuckle assemblies, and half the weight of the half shafts could either be eliminated or drastically reduced in size and weight depending on the design of the wheel motor. Here again, the unsprung weight issue isn't problematic as long as the design of the wheel motor is kept as light as possible. The biggest problem I see is in the front suspensions of rear wheel drive vehicles or the rear suspensions of front wheel drive vehicles. Here, the only weight to be eliminated would typically be the knuckle/hub assembly and some brake components. Even in this case, though, the weight increase of a wheel motor over the removed components would be minimal as far as I can tell. I think it would be possible to all but eliminate any minor weight gain by using a lighter weight aftermarket wheel and tire combination. I think, through proper engineering, the unsprung weight debate will be a virtual non-issue.


Why not a combination of sprung/unsprung motors? It is estimated to take 20-25 HP at 65 mph level... which, if I am not mistaken, would be about 20-30kw of electric motor capability... why not split that, put a 10-15kw hub motors on the rear (of a FWD), they provide the base motive force, especially steady state at highway speed. They would be unspring weight, but relatively light - lose the mechanical brakes entirely on those wheels, regen only. 

Then, put a couple of larger motors (40-60kw each) in the front, one on each half-shaft. In normal operation these motors would just freewheel, or provide additional regen braking on downhills, extra torque on uphills. These front wheels could retain their mechanical brakes, and existing steering.

I'm new here so I haven't read many of the threads yet, but I haven't seen this mentioned in this thread... apologies if it's covered somewhere else...

What say you?

-John


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## unclematt (May 11, 2008)

Can people please do me a favor and post if you are an electrical engineer or have experience actually building motors? We seem to be getting off on all kinds of tangents instead of discussing the actual design and build of a wheel motor, as the thread title states. I understand that people have ideas, but I recomend you start a new thread to discuss your thoughts on alternate topics.

We need to decide on our wheel motor objectives and then figure out ways to achieve them.


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## unclematt (May 11, 2008)

Hi-Pa Drive is an integrated motor and drive electronics in one unit. 

Hi-Pa Drive is ultra high power density - 20 times more than conventional systems 

Hi-Pa Drive is ultra reliable – 20 times more reliable than conventional systems 

Providing high torque in a lightweight flat motor package, Hi-Pa Drive is ideally suited to vehicle in wheel drives, where its impact on suspension dynamics is minimal.

*HPD40 *
*HPD35 *
*HPD30 *
*Torque (max) *
750Nm 
500Nm 
350Nm 
*Speed (max) *
2000rpm 
2000rpm 
2000rpm 
*Power (max) *
120kW 
80kW 
40kW 
*Mass *
25kg 
21kg 
18kg 

*Key Features:~ *
Full regenerative braking down to very low speed 
Full holding torque at zero speed 
Wide speed range 
Built in brake resistor (for full charge regeneration situations) 
Hand / parking brake option available 
Heavy duty bearing system 

*Inputs *
+ve power 
400vdc max 200A 
Uv power 

Throttle input 
pwm 20khz 
Brake input 
pwm 20khz 
TC Input 
pwm 20khz 
Forward 
digital 24v pos true 
Reverse 
digital 24v pos true 
Enable 
digital 24v pos true 
CanBus 

Here is some information posted on PML Flightlink's website. The fact that they are using variable DC and a brushless design is interesting, and may be a viable design otpion for us as well. Correct me if I am wrong, but it looks like they have a large, brushless motor much like a motor used on RC planes. I read elsewhere that their motor is a "28 phase" design. Can anyone enlighten me as to what this means exactly? Does this mean permanent magnet number? poles? what?

Can anyone else offer constructive analysis of the PML information? Can we glean any further design ideas from this info?


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## unclematt (May 11, 2008)

oops, I have a correction: PML says it is a 24 phase, not a 28 phase:
from the PML website

*"Specifications:

Motors*
4 x 750Nm 1800rpm high efficiency Brushless permanent magnet sine wave *Hi-Pa drive™* 24 phase water-cooled

*Drive electronics*
4 x 480Amp 450V *Hi-Pa drive™* 24 phase sine wave inverter IGBT water cooled CAN bus communications

*Battery*
300V nominal 70Amp Hour Lithium Polymer 700Amp peak

*Battery Management system*
Active cell balancing, temperature and voltage monitoring CAN bus communications

*Ultra Capacitor*
350V 11 Farad 700Amp limited

*Energy re–circulator*
1400Amp continuous IGBT water cooled CAN bus communications

*Generator*
Engine250cc 2 cylinder 4 stroke gasoline 15kW at 7000rpmGenerator20kW continuous at 250V 80AmpController350V 80Amp water-cooled CAN bus communications"



Can we use any of this to reverse engineer our own design that is close, but not exactly the same?


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## Ioku (Sep 27, 2007)

Originally Posted by mattW


> I just had a thought that we could put 'skid steer' as one of the options for the controller i.e. right hand side wheels to move forward and left hand to move back. Then you can turn on less than a dime just like a tank... lol wouldn't do the tyres much good but would be amazing on narrow streets for U turns!



I know I would use something like this I think it would be one of the coolest parts of having wheel motors.



> On most rear wheel drive vehicles, the weight of the entire differential/rear end housing is unsprung. So is the braking assembly and half the weight of the drive shaft and half the weight of any control arms. This alone could more than offset the weight of a properly designed wheel motor.


Well this I really only true of trucks and some suvs and some very old cars, But most all rear wheel drive and all wheel drive cars have independent rear suspension now even a lot of the suvs do.

But I think the big this to deal with, with in wheel motors will be acceleration. With no gearing you cant use rpms to create torque so the motor will have to be able to make a lot of 0 rpm torque to get the car moving.


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## aeroscott (Jan 5, 2008)

JRK5150 said:


> I think we should first look at the current cutting edge of technology in wheel motor design. If you don't already know about PML and their Hi-Pa drive wheel motors, check them out here.http://www.pmlflightlink.com/motors/hipa_drive.html
> 
> Next, I think we should make sure that we do NOT infringe on any patents. To this end, I suggest keeping this as simple as possible. We can get fancy later. Getting sued developing a free drive system would severely suck!
> 
> ...


no patent infringement unless financial gain


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## Manntis (May 22, 2008)

aeroscott said:


> no patent infringement unless financial gain


theft of intellectual property is independent of financial gain.


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## aeroscott (Jan 5, 2008)

Manntis said:


> theft of intellectual property is independent of financial gain.


 I googled it what a mess . have there been any cases of patents copied buy non commercial interests only to be found in violation of " theft of intellectual property " .


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## Madmac (Mar 14, 2008)

Use of a patent for personnel education is not a breach. Selling that work would be. Taking the approach of not using something that is patented would limit the design severely, particularly US patents as they are granted without any requirement for originality.

Doing something that may infringe one or more patents has the advantage of making sure someone cannot take the work and make a business out of it. 

Down side is everybody would have to source all their own parts to build any design.

Madmac


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## Manntis (May 22, 2008)

Madmac said:


> Use of a patent for personnel education is not a breach.


building and using an item isn't usually considered "personnel [sic] education".



Madmac said:


> Taking the approach of not using something that is patented would limit the design severely


An IP lawyer, and the owner of the IP you're using, would tell you "Tough - that's what licensing is for" 

(Patents aren't the only form of intellectual property ownership, BTW).


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## JRK5150 (May 18, 2008)

I think the idea of using inboard motors to eliminate the problems of wheel motors is a good idea, but it defeats many of the purposes of using wheel motors in the first place. I see the self contained wheel motor as a way to eliminate the traditional drive train in vehicles, and thus, free up space for other things. A drive system that takes up no more space than the wheel itself would free automotive design to move in any direction it would please.
As for the mounting of our open source motors, I feel that a standardized mounting pad with standardized bolt patterns on the inboard side of the motor would be the most universal approach. With this design, an adaptor plate that would fit on the mounting pad could be easily fabricated for any sort of suspension found in any vehicle. With this universal mounting pad design, an adaptor plate could be fabricated for any suspension type, and thus, one wheel motor could be unbolted from a front strut assembly and could be bolted to a rear irs assembly with dual A-arms, provided each had an adaptor plate made for it.
The question of AC vs DC should be handled by someone with a better understanding of the subject than myself. I have read that AC systems are more efficient, so I suggested AC, but I have little in depth knowledge on this subject.
I do, however, think that a brushless design would be the best way to go for several reasons. First, the motor should be designed as a sealed unit to prevent water, dust, and debris from getting inside. A brushed design has to be opened periodically to replace the brushes, and would need to be re-sealed. Also, regenerative braking would be much more complicated with brushes. 
As for experience, I have mainly an automotive/ fabrication background. I have built and modified several quick cars and would like to apply these skills toward our common goal. I have an oversized three car garage that is stocked with most of the tools needed to pull off the task of fitting and testing the drive system and I wouldn't mind buying more. As for the actual motor building, that would depend on our design. I've also been asking around locally, and have found several people who would be very happy to help. Unfortunately I haven't run into any electrical engineers yet.


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## Bowser330 (Jun 15, 2008)

Ok so we need to start making decisions and logging them so that this goes from Idea stage to REAL stage...

so far are we in agreement that its going to be an AC motor (brushless) with a sealed design for wheel applications...

If someone doesnt want to use it as a wheel motor, adapaters can be made to pull it within the car. Done.

Have we discussed the amount of power the motors will have? What is adequate? what is overkill? Are we making one size fits all?

lastly, It eats me up inside to see how much companies are charging for electric motors and controllers.. Its rediculous! AC-Propulsion wants 25,000$! Its flat out greedy...


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## JRK5150 (May 18, 2008)

Alright, simply to nail down the specifics so we can move on, does 40kw seem to be agreeable as the target power for each motor? Also, a brushless permanent magnet motor seems the best way, but can we make a final call on AC vs DC. 

Once we finalize the target power and electricity supply type, we can move on to physical dimensions, materials, and component selection. If we simply take it one small step at a time, we will all be cruising around in our wheel motor powered machines in no time!


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## judebert (Apr 16, 2008)

40kw sounds maybe even a little large. That's about 54HP; all four wheels would provide 216 horses! Still, I'll go for it. 

I'd prefer AC induction motors with force-vector controllers.


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## Bowser330 (Jun 15, 2008)

judebert said:


> 40kw sounds maybe even a little large. That's about 54HP; all four wheels would provide 216 horses! Still, I'll go for it.
> 
> I'd prefer AC induction motors with force-vector controllers.


Check this AC motor out for a reference point...

the most powerful version is 3200$ and it comes with a controller...

Almost 50hp and 105 ftlbs torque from a very small package, its only 1 foot long and 7 inches diameter...Ive seen obese kids lunch boxs larger than that!

http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php


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## Gravitic Anomaly (Jun 19, 2008)

If there are folks who are seriously interested in an open source motor project, I might be willing to help out. Prototype motors are likely to cost around $1000 USD each. This is based on an individual locally sourcing the components and doing the construction theirself. (no, I am not offering to make or sell anything)
This would not include the cost of the controller/drive. I would keep the drive as simple as possible at first. Once a sound motor design has been achieved bells and whistles can be added.
I believe it would be best to start out with a motor to fit a GM transaxle as the only drive motor and then modify this design for wheel motors. Otherwise the project could easily be bogged down with suspension and brake modifications and the initial goal lost.

Cheers,
GA
_If it walks, crawls, rolls, flies, or swims I have designed a motor for it._


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## JRK5150 (May 18, 2008)

I agree with the idea of keeping it as simple as possible to start. I do think we could build a test bed car with more traditional motors used at the wheels, though. This would be a bit complex at first, but would allow for the development of a simple control system. Suspension fabrication isn't too difficult if we aren't getting fancy, and I wouldn't mind pitching in on that. We could then prototype the wheel motors. If we take this in steps, it shouldn't be overly complex. The first step is to agree on the basics, power, AC vs DC, etc. Then we can work on building a test car. 

So... what do we think? AC or DC?


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## Bowser330 (Jun 15, 2008)

I am not a fabrication expert or a specialist in this area, in fact I didn't do well in my elec. engineering class in college but what I do know is that this motor is better off AC. Regen will be a huge asset, plus the linear torque design of an AC doesnt require any gear reduction...

What do others think?


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## 3dplane (Feb 27, 2008)

The same can be said with BLDC(3 phase perm.mag.brushless dc outrunner) (Wich is what is on the little picture in post 71).In addition such motor is very easy to tune to a specific application. By that I mean starting out with a certain size stator,one could manipulate the motor to have the best rpm/torque compomise for the application.This will require trial and error for the first one but after that no need to play with the design.Electronic"gear reduction" is achived by the nature of the motor as in that the rotor(with the magnets in it) (also the wheel in this case) does not follow the stators rotating magnetic field 1:1.Instead when the next set of phases are energized the rotor just steps the closest set of magnets to align with the next phase.Resulting in the rotating magnetic field have to do several revolutions to make the rotor (wheel) do one revolution.Here is one thing where it can be manipulated by the number of magnet POLES used(not always the same number as magnets).The electronic gear reduction is going to be half the number of mag poles.
Example:16 poles would give 8:1 etc. Also there is a load of other things that will "tune" the motor but its too long to list. I tried to stay out of this thread because I don't see this happening on the DIY level due to the complexity of the system incliuding controller availability and solving brakes and such,but the only options I saw mentioned was AC or DC so I thought I throw this in the mix. Barna


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## JRK5150 (May 18, 2008)

I think we have made a little progress. The consensus seems to be that our motor should be brushless and either AC or brushlessDC. Which one would fit our needs best? As for this DIY project not being able to happen, I see no reason why it can't. It may be difficult, but the alternative is to wait for the prices of currently available systems to come down to a reasonable level. I don't see that one happening! The availability of control systems isn't a problem because we seem to be planning to design our own. As for the braking problem, the simple solution at first could be to use a small disc mounted to the hub between the motor and the wheel. This project is *VERY* possible given the knowledge base world wide and the willingness of many of us to actually develop the designs in the real world. I, for one, am sick of waiting for the next best thing, only to be sold on the idea of vaporware just over the horizon! If we want something like this, we need to make it happen!


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## John (Sep 11, 2007)

judebert said:


> 40kw sounds maybe even a little large. That's about 54HP; all four wheels would provide 216 horses! Still, I'll go for it.





judebert said:


> I'd prefer AC induction motors with force-vector controllers.




Power is a product of torque and revolutions and torque (depending on OA wheel diameter and vehicle weight) is what provides your grade ability and acceleration. With a hub motor you're going to need a lot of torque because your revolutions are going to be very low. If your motor has a nice flat torque curve with more or less constant torque it won’t produce its maximum power until close to its maximum revolutions. If these maximum revolutions are far too high to direct drive a wheel, torque (even at 40kW of power) is going to be inadequate without a reduction box.

The reference motor from electric motor sport produces 105ftlb torque. Using a 24 inch over all diameter wheel this would translate into 105lbf driving the vehicle multiplied by four wheels 420lbf. If the car was 3000lb and disregarding rolling resistance this would equate to 0.14g acceleration during the flat part of the torque curve and a maximum grade of about 8 degrees. It would be unacceptably lethargic despite having acceptable power due to the motor not running out of revolutions until the car is doing about 560mph. A 4:1 reduction box would improve acceleration to 0.56g and gradability to 34 degrees and reduce top speed to 140mph. Looking at the torque curve the motor quite quickly drops off the flat part of the torque curve so it wouldn't maintain this acceleration or gradability to very high speed. I think it would be advisable to avoid the added complexity and weight of a reduction box.

The unique high torque low rpm requirement is going to dictate the design to some point.


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## JRK5150 (May 18, 2008)

This will be a unique and interesting design challenge for sure! John, do you have any suggestions for the design? Still trying to pin down the AC vs DC thing. By quoting judebert, are you agreeing with his idea for an AC induction motor and force vector control?


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## Madmac (Mar 14, 2008)

Surely the requirement for an open source motor should be a low cost replacement for a single motor conversion. 

Doing a wheel hub motor requires extensive modification to the vehicle to fit on all four wheels. Four times the control are needed and the development of overall control, to avoid one motor causing the vehicle to not drive straight is difficult. Design of safety system so that failure of one motor does not cause the vehicle to suddenly pitch left or right on the free way is, again, not simple. Because of the complexity of this design anybody who succeeds is not going to make it freely available it will command a high price in industry

It would seem a better solution to develop a low cost, light weight and high performance AC motor. Along with a parallel design of low cost controller with built in charger. This allows easy mechanical modification of vehicles, increases performance and range as well as providing a lower cost solution. The work required is less and it would be of much wider use to the EV community. AC Propulsion is a small company and they hand build their motor in low volume. A search of Google patents is an easy way of finding out what is involved in induction motor design for EV use.

Sourcing a base of an aluminum industrial motor and modifying the case for water cooling as well as redesigning the rotor seems to be a more realistic challenge.

Comments!!

Madmac


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## Gravitic Anomaly (Jun 19, 2008)

All polyphase motors are in effect AC motors. All motors, including brushed motors can be used with a regeneration controller.
The advantage the PM brushless motor has over other types such as induction and SR motors is that it does not have to create a stationary rotor field. Induction motors induce a rotor field by transformer action. The power comes from the current in the stator windings. The rotor cage has resistence, inductance, and iron losses which "waste" a lot of power as heat. Because of this the motor is less effiecent than a PM motor. The torque curve for an induction motor peaks similar to an IC engine and requires the motor to have gearing to keep the operating speed near the peak of the curve over the range of vehicle speed. A vector drive helps to flatten the torque curve, but not entirly. An induction motor designed for electric vehicle operation would need to have a copper cage, and be designed for 400Hz operation or higher for best effiency. The level of difficulty of building or of modifying an induction motor is much higher than that of building a PM brushless motor. Anyone with access to a machine shop and some possesing craftsmanship can build a PM brushless motor at home.
Hub motor are an interesting subset of PM motors. For a car wheel the motor would be designed for approximatly 0-1000 rpm. Since the speed is low lesser grade core materials are required and higher energy product magnets can be used. This will produce an almost flat speed/torque curve when driven off of a sine drive controller. Unlike a IC engine maximum power can be applied across the normal speed range so the need for gearing is reduced or eliminated. A motor might be rated at 105 ft-lbs continuous torque, however you can get much more than the rated torque if you can push the current to it. This is no different than with an IC engine. If you want to smoke the tires you give it more gas.
Most hub motor vehicles that travel at speeds over 10 MPH will use two motors, not four. Two in the back driving and the unpowered wheels in the front steering. This way motor failures do not cause steering issues. This setup also leaves the front brakes available for stopping if the motors or regen should fail. A rather nice safety feature to have.
Regeneration via the rear motors is still possible using a set up much like a brake controller for trailers. (Hrmmm, a brake controller might be just the way to go on a homebrew motor control)
For simplicity, and so it can be used with front wheel drive cars, I think a PM Brushless outer rotor motor driving a manual transmission is the way to go for most people.


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## Bowser330 (Jun 15, 2008)

Gravitic,
When i search google for "DIY PM brushless motor" 99% of the links take me to motors for hobby RC airplane motors which are weak sauce for what we need power wise....

Can you link us to where we can find information on building a PM Brushless motor of appropriate size for EVs etc?

How complex does the controller have to be for a PM brushless vs. an AC induction motor?

How does this motor (linked) and corresponding controller stack up?
http://www.electricmotorsport.com/store/ems_ev_parts_motors_pmac.php

Would it be possible to just "scale up" the size of the motor in the link above? would that generate more power out of it? I think it would keep the contruction difficulty to a minimum as you have an exact model to follow, additionally, the controller would also just have to be scaled up to handle additional voltage and amperage...no?


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## 3dplane (Feb 27, 2008)

Bowser!
I know your question is not directed at me but the way I see it is the easy and cheap part of this is to actually build the motor. My question is : what are we going to use for controller and how much does it cost? I know I can't build one! You were at the right place at the rc plane motor building sites.Thats the motor we are talking about.(hence my screen name).I've built quite a few and all parts were other people's junk.(except the neodymium magnets) Ranging from tiny one ounce 20 000 rpm(for fast planes) to running my bycicle down the road(cadillac blower motor rewound and fitted with neo mags) the last one I built never even made it on anything because I don't have a controller big enough to exploit the potential of the motor.(8 pound motor using ceiling fan stator) The model world is up to 12 KW out of a 3.5 pound outrunner motor(plettenberg predator) I know source for big enough stator(the only part I cant make) to power a car but again, no controller. so just because I could build a brushless motor next to free to power a car does not mean it's the best way to go(for me anyways) When models have a 40KW controller available that is AFFORDABLE you bet I'm building that motor.
BTW the motor in the link is an axial flux design (not an outrunner) does not lend it self for optimizing rpm/volt as easily but it was not meant for hub motor (too high rpm,too small etc).Good for motorcycle conversion.
You can obviously upscale any motor but not without serious modification to number of turns, different wire size etc.so basicly building a new motor making following a design pointless.I meant this as "the way I see it" because I've done some of it but don't let that stop the people persuing this.Now go out there and build something! Barna


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## Bowser330 (Jun 15, 2008)

Thanks for the reply...so i guess i was wrong about the RC motors being weak sauce, looks like they can and are being built pretty powerful.. man i wish you weren't literally across the continent from me, It would be cool to have your help on building a large burshless motor...

I guess we will need to keep hitting the boards about the controllers..there is bound to be someone who knows how to take this... (see link)

http://www.robotpower.com/products/osmc_info.html

and make it handle the parameters we need....for our motor...


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## Madmac (Mar 14, 2008)

The link is to a PWM output stage to drive a DC brushed motor. It could be used in other applications but better options are out there. 

I think several members who post are working on their own AC induction controllers. The permanent magnet brushless motors are effectively AC synchronous motors and the same control hardware can be used.

If you do a search for BLDC motor control there is plenty of technical information and application notes. Most is related to small devices though.

Madmac


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## Gravitic Anomaly (Jun 19, 2008)

The model airplane world of motors is an odd mix. In some ways it is on the cutting edge and in others it is in the stone ages. However almost any hobbist can and do make their own motors. Me being one of them.
You will find some good basic recipies for the motors and and equal amount of dis-information.
A motor large enough to power an automobile could be no more difficult to build.
Rather than trying to upscale an existing design you are better off designing from scratch. I think the simplest motor would be a PM brushless motor built onto a manual transmision/transaxle. The stator assembly would be bolted to the transmission housing and the rotor would be attached to the transmission input spline. This way the builder does not need to make housings, shafts, or add bearings. All the pecision machining is already done. The motors airgap would be relativly large for this type of motor. This is to make the assembly more tolerant of misalignment, more resistent to demagnetization, and run cooler. 
Builders will have to be warned to closely follow the assembly instructions. If handled carelessly the rotor will quite happily destroy bearings or chop off fingers when placed over the stator.
I first used this type of motor in the early '90's on a turbine powered motor/generator project that was jointly funded by the DOE and a major automaker. It was a test bed for a bi-directional inverter concept.
A controller for a PM brushless motor is easier to build than an AC vector drive. A industrial vector drive can be used to run a PM brushless motor if it has the right software. Many of the higher end ones have this built into them.
I can design a suitable drive for the motor. We need an experianced board designer and electronics prototype guy to do the hardware.
I have too little time and too many projects to build prototypes myself. I will work with someone willing to put the time and money into building a prototype motor. Including sources for all of the parts. For strictly selfish reasons someone converting a Fiero would be preferred.
The motor cross section I previously posted is of a radial flux, outer rotor hub motor I did a few years ago for an unmanned vehicle. It was roughly two foot in diameter.


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## judebert (Apr 16, 2008)

3dplane said:


> Bowser!
> I know your question is not directed at me but the way I see it is the easy and cheap part of this is to actually build the motor. My question is : what are we going to use for controller and how much does it cost? I know I can't build one!





Gravitic Anomaly said:


> A controller for a PM brushless motor is easier to build than an AC vector drive. A industrial vector drive can be used to run a PM brushless motor if it has the right software. Many of the higher end ones have this built into them.


I would like to make my part in this project clear. I'm a programmer, by trade and inclination. I have experience in many computer languages, almost entirely C or higher-level, but a very little embedded and real-time experience. 

I am formally offering to donate my programming time for _any_ controller designed for use in a highway-capable electric vehicle, under one condition: anyone must be allowed to use and modify the resulting code. (Like the GPL.)



Gravitic Anomaly said:


> I can design a suitable drive for the motor. We need an experianced board designer and electronics prototype guy to do the hardware.


You build the motor, someone else builds the controller, and I'll program it. Where are our electronics guys?



Gravitic Anomaly said:


> Rather than trying to upscale an existing design you are better off designing from scratch.


The other controller designers on the forum (or is it the EVDL?) seem to think differently. I don't know enough about it to say. 



Gravitic Anomaly said:


> I think the simplest motor would be a PM brushless motor built onto a manual transmision/transaxle. The stator assembly would be bolted to the transmission housing and the rotor would be attached to the transmission input spline. This way the builder does not need to make housings, shafts, or add bearings. All the pecision machining is already done.


Interesting idea. I kinda like it. It doesn't take advantage of the previously stated advantage of brushless DC (good torque at low RPM), but it's definitely the elegant solution.

I'll restate my ACIM preference, while I'm here. For my own selfish reasons, I would prefer a motor as maintenance free as possible. That means no brushes. I understand ACIM better than brushless DC, but only barely. I'll still be happy to program a brushless DC controller, too. 

I'd also like regen, and a smart charger built into the inverter/controller.

If we were doing requirements analysis like we do on software projects, I'd want:


The drive system shall be maintenance free after installation.
The drive system shall operate the vehicle from stationary to top speed without requiring the driver to shift.
The drive system shall recharge the energy storage system using energy recaptured during braking.
The drive system shall recharge the energy storage system using energy provided from an electrical outlet.
That's what I'm willing to work for. Design me a system that fulfills those requirements, and I'll be staying up late to program it for you.


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## Gravitic Anomaly (Jun 19, 2008)

If the battery pack and controller can provide the current the motor will be able to provide peak torque at 0 rpm. Smoke 'em if you've got 'em.
I would add to the list of desires:
The controller/charging system shall be capable of accepting on-board generators for hybrid operation.

My work will be open source, free to use for NON-Commercial purposes. Including the design, instructions, drawings, & schematics. Offered as-is not warrented. Suggested sources of components are not affiliated with me in anyway financial or otherwise. Commercial sale of components, kits, drawings, circuit boards, ect. can only be arranged through the principles involved with the development. The selling of the open source information on Ebay® is strictly prohibited.

- GA


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## Madmac (Mar 14, 2008)

I am in the early development stage of an expanded version of the Circuit Cellar AC motor driver. I have added a two phase boost circuit to allow control of regeneration voltage to battery charging, PWM driven load resistors to loose regeneration voltage when batteries are fully charged and a 3 phase bridge driver rated at 600 volts 400 Amps. 
My interest is in driving a Ford/Siemens AC motor that I bought surplus. I will be doing a 4 layer PCB with the drive circuits and an interface to a BMS, I am also working on, and a USB interface to a car PC for data logging and monitoring.

If some one wants to do the firm ware to support a BLDC motor I am willing to supply either the gerbers or boards (at cost). This would be under the same conditions as the post above....no commercial use. Supervisor is a Silicon Labs 8051 derivative and DSP is a Microchip dsPIC30F6010. PM me if you are interested.

The current design, not yet finalised, may need a few additions to support BLDC motors depending on position and current sensor arrangements.

Madmac


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## CNCRouterman (May 5, 2008)

I have a CNC router, which means I can machine most materials, but not rock, steel or glass. I have a customer with a very high end CNC punch, and that might be even better for some components. I would like to get on this wagon and contribute to the project. Personally, I am still a bit skittish about hanging the motor in the wheel, but an aero engineer friend of mine (who also has an automotive engineering background) explained a lot of the advantages as well as addressing my concern about unsprung weight. That said, I would still probably lean towards mounting the inboard and using CVJs and half shafts.


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## manic_monkey (Jun 24, 2008)

Hi all. I found this site a couple of weeks ago and am really fired by the idea of open source motor building. Seems like a great way to share knowledge and work for a common goal  

Ive still got a lot to learn about motors, so please forgive me if some of this is a bit simple.

theres a lot of talk about going for a bldc design, but most of the focus seems to be on outrunners. would an inrunner not be a simpler design? i understand they provide less torque, but at this sort of power and size, it would surely still be far more than a car engine. also, wouldnt an inrunner require less magnets? one thing which concerns me is the magnets that will be require to make an effective bldc. neodymium magnets of the required size would surely be very expensive, but more importantly, they would be very very difficult (and possibly dangerous) to work with. ive seen 50x50x25 (mm) magnets that produce 90+kg of force, so i imagine the magnets for a 40kw plus bldc would be similar. 

I understand that going BLDC means a less complex controller is required, but it seem that by doing so, the complexity is being passed onto the manufacturing side. (making it very difficult for a homebrew enthusiast to make it)


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## 3dplane (Feb 27, 2008)

Hey manic!
One of the things makes outrunners easy to homebrew is that the magnets are not going anywhere in the bell.Centrifugal force just helps them stay put.In an inrunner one would have to use maybe kevlar wrap or some kind of pretty sturdy method to make sure the mags not going to fling off.Rewinding an outrunner is also a breeze compared to an inrunner. The stator arms on the outrunner are like open fingers(on a hand) making the task of wrapping wire on it easy compared to imagine a ring with sharp fingers pointing to the inside of the circle and wind wire on them(neatly) for the inrunner.
So no an outrunner is a heck of a lot easier to construct on the diy level then an inrunner. Btw welcome to the forum. Barna


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## manic_monkey (Jun 24, 2008)

ahh yes, i see what you mean. even at relatively low rpm, the weight of the magnets would put an inrunner under a lot of strain. 

while your here, could i pick your brain for a second on outrunnners / BLDC?

does the thickness of the bell material have much of an effect on motor efficiency? (larger iron mass, magnetic fields, et al)

should the core material be made from soft iron, or is mild steel enough?

back to the point of hub motors. if two wheels are driven seperately, the electronics will have to function as an active differential (speed one up, slow the other down) to ensure you go round the corner. has anyone given much thought to how the controller could sense the amount of difference needed?


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## John (Sep 11, 2007)

Have you considered using a halbach array (for the permanent magnets) and dispensing with the flux ring? The bell could then be a non-magnetic material.


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## 3dplane (Feb 27, 2008)

Hey Guys!
The flux ring is very important to have a closed magnetic circuit.It has to be thick enough to stop flux leakage for an efficient motor.It kind of concentrates the magnetism back toward the coils and arms.Now if you have brutal magnets in there for whatever reason you can get away with thin material but that's kind of wasting money on magnets. In my case I only had a couple of small motors that I actually machined an aluminium bell and employed a flux ring.The larger ones(non model aeroplane) I did not worry about weight and went with simplicity so the whole bell was one piece of ferrous material(already made for something else).
John! LOL I have no clue what a halbach array is but it sounds like a set of German solar panels.
Manic! If you mean the stator material by saying core,yes that is probably the heart of efficiency. the laminations are isolated and the thinner the better to reduce eddy currents,and I believe it is made out of silicon steel. I previously mentioned that is the part I can not make so that is what my motors get built around.
GRAVITIC ANOMALY !
Was that unmanned motor(itself) two feet in diameter? Would you please tell us more about it if it's not secret?! Like where did the stator come from? and how it turned out (the motor) Thanks! Barna


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## John (Sep 11, 2007)

http://en.wikipedia.org/wiki/Halbach_array


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## 3dplane (Feb 27, 2008)

John that's interesting! Looks like my guess as to what it is ,was not even close. I have to think that the flux ring is doing the same thing as the "intermediate" magnet (field to the side) does in the halbach.But with less magnets and the fact that the magnet wants to stay where it's supposed to for obvious reasons.Like I mentioned earlier creating a closed magnetic circuit.On that note, the polarity is always alternated in the motors.Even if the pole is made out of multiple magnets.Example instead of N-S-N-S it could be NN-SS-NN-SS etc.(wich is how I shot super glue in my eye once)(they repell each other side by side that way) Barna.


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## LeTank (Jun 24, 2008)

You know, I thought about this one. I even looked up their patent. Guess what.. Its a simple wind generator idea that charges the car with a wheel instead of wind.. Ok, then, so why can't we just make one wheel of the vehicle spin a wind generator motor? (Those smaller wind generators are about $600 bucks). So you have a one wheel drive car, but you get about 1kw of power at cruising speeds. Maybe its less power, but still you have a heck of a charge going to your batteries. 
Maybe someone has a better place to place it on the vehicle.. any ideas?


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## John (Sep 11, 2007)

3dplane said:


> John that's interesting! Looks like my guess as to what it is ,was not even close. I have to think that the flux ring is doing the same thing as the "intermediate" magnet (field to the side) does in the halbach.But with less magnets and the fact that the magnet wants to stay where it's supposed to for obvious reasons.Like I mentioned earlier creating a closed magnetic circuit.On that note, the polarity is always alternated in the motors.Even if the pole is made out of multiple magnets.Example instead of N-S-N-S it could be NN-SS-NN-SS etc.(wich is how I shot super glue in my eye once)(they repell each other side by side that way) Barna.


So do you think this would simply do the same job as the flux ring (without increasing flux density?) while greatly increasing assembly difficulty? Total net gain the motor is lighter by one flux ring.


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## 3dplane (Feb 27, 2008)

I would say yes.Don't forget about the weight of the magnets too.
Barna.


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## manic_monkey (Jun 24, 2008)

3dplane - in an earlier post you said you knew where you could scavange a good size stator from. is there any chance you could share the knowledge?  largest ive seen that are easily available are motorcycle magneto / generators, and they dont look anywhere near bg enough


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## judebert (Apr 16, 2008)

Gravitic Anomaly said:


> The controller/charging system shall be capable of accepting on-board generators for hybrid operation.


Let's just modify #4 to specify the sorts of electric current allowed: The drive system shall recharge the energy storage system from 120V 60Hz single-phase AC, 240V 60Hz three-phase AC, or DC current from 120V to 240V.



Gravitic Anomaly said:


> My work will be open source, free to use for NON-Commercial purposes. Including the design, instructions, drawings, & schematics.





Madmac said:


> ...no commercial use.


I understand where you're coming from, but I recommend reconsidering your "no commercial use" clause. What is your ultimate goal, and how does prohibiting commercial use achieve it? 

If you want to allow others to build their own motors and controllers, then prohibiting commercial use doesn't help at all. It might even hurt. Someone with a commercial interest can put money into development; if they have to share their enhancements (as per the GPL), then the private builders benefit from the commercial use. (Think Novell SUSE, or WINE, or busybox.) If commercial use is prohibited, then development will never progress beyond the community we're building here.

If you want to make money by selling them yourselves, and you're trying to prevent competition, prohibiting commercial use is of very limited use. If everyone uses the same clause, you'll have to get licenses from everyone involved, since we don't even have a 'project' to hold the copyrights. Consumers who want to build their own still can, completely bypassing you. Consumers who want to buy one would rather buy from the developer than a knock-off company; all you have to do is make certain that you're credited (again, as per the GPL), and they'll find you and purchase from you.



Madmac said:


> I am in the early development stage of an expanded version of the Circuit Cellar AC motor driver.
> <snip>
> If some one wants to do the firm ware to support a BLDC motor I am willing to supply either the gerbers or boards (at cost). This would be under the same conditions as the post above....no commercial use.


What would that cost be, by chance? I'm interested, but I can't develop firmware under the "no commercial use" clause.


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## JRK5150 (May 18, 2008)

Alright, this is great! We seem to be making progress now! The general consensus seems to be for a brushless DC motor with a permenant( probably neodymium) magnet outrunner. I understand the desire to adapt this to a standard drive train, but that cancels out many of the advantages of the wheel motor concept. My vote is to proceed with the design as a pancake style motor intended for use inside a vehicles wheel. If we start with the rear wheels only, the control system will be much less complex. Will a 40kw power rating be enough if the motor is properly designed? If I may suggest we also set the goal of keeping the cost of the final system as low as possible so that most people will be able to afford it.


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## Madmac (Mar 14, 2008)

> If I may suggest we also set the goal of keeping the cost of the final system as low as possible so that most people will be able to afford it.


Going for a hub motor instantly increases the cost. A single motor with controller will always be cheaper. It is also a bit more reliable.



> What would that cost be, by chance? I'm interested, but I can't develop firmware under the "no commercial use" clause.


Difficult to give a price at this point. I have not been designing for least cost that is for sure. I am designing something that will do more than commercial systems at far less cost. With regard to no commercial use. I have put designs in the public domain before and ended up seeing them being sold for profit. I have no issue with a commercial operation as long as they do not exploit. In my case a good contribution to charity's that can be publicly verified would be fine.

Madmac


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## manic_monkey (Jun 24, 2008)

i think 40kw per wheel may be a little extreme. as a drive train motor, thats probably fine, but as a hub motor that would be 80kw 2wd, or 160kw for 4wd. at this point i would say that we should forget the controller, and focus on the motor.

I agree that a neodymium outrunner seems to be the way forward. My only concern is the cost and sourcing of magnets in the right size might make an AC motor look like a better proposition. 

what i would really like is some discussion on physical motor size; especially the stator depth / width. i believe that the stator size is related to the max power of the motor (or at least the maximum efficient power of the motor) due to magnetic saturation. also, where the motor is to be mounted will most likely effect the possible size.


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## John (Sep 11, 2007)

judebert said:


> Let's just modify #4 to specify the sorts of electric current allowed: The drive system shall recharge the energy storage system from 120V 60Hz single-phase AC, 240V 60Hz three-phase AC, or DC current from 120V to 240V.


Don't forget most of Europe, and Australasia, (just to mention a few places) use 240v single-phase at 50Hz (and 415v three-phase). Think outside of North America this is after all the world wide web.


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## Manntis (May 22, 2008)

John said:


> Don't forget most of Europe, and Australasia, (just to mention a few places) use 240v single-phase at 50Hz (and 415v three-phase). Think outside of North America this is after all the world wide web.


that said, North America remains the world's largest car market and provisions for a smart charger that can take either 120V or 240V will make any EV project more viable


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## John (Sep 11, 2007)

manic_monkey said:


> i think 40kw per wheel may be a little extreme. as a drive train motor, thats probably fine, but as a hub motor that would be 80kw 2wd, or 160kw for 4wd.


 
I think power in this application is a bit of a distraction from what is the most important parameter to consider which motor torque is. You have no gear reduction to amplify torque so what the motor produces is what you get and that coupled with the rolling radius of your wheels determines your driving force which in turn coupled with the vehicle weight decides your grade-ability and acceleration and also how effective your regenerative braking will be. Most direct drive systems require huge amounts of power to meet their torque requirements across their required rev range. A regenerative only braking system would require vastly more than 160kW (see post 51 of this thread).


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## 3dplane (Feb 27, 2008)

John!
About no gear reduction: in post #74 I made an attempt to explain where the torque comes from in an outrunner.It's like an invisable planetary gear set.And it works! My "slowest" motor (32 poles=16:1) when I did the first runup test I laughed at the rpm at full speed (about 360rpm at 12v) and casually grabbed the bell to stop it, well, it twisted the motor out of my other hand holding it! The only limiting factor for rpm would be the controller's ability to fire the phases fast enough.That said, when we upscale motors like this the whole inductance thing might require the controller to be nothing like the one for the tiny motors.(thats the part where I'm pretty clueless) That is another reason I'm waiting for GRAVITIC ANOMALY TO COME BACK (I hope he heard that) with some info on that two footer he built. 
Manic !
No secrets. While hanging around windmill sites(web) I saw people using Fisher & Paykel washing machine motors for generator.They are basically huge outrunners. I did not really look into them but maybe you guys could do that. Criteria!: the number of arms on the stator has to be divisable by three! to make a motor for our purpose. If stator lenght(pancakeness) is not sufficient identical stators can be stacked to make a longer more powerful motor. Barna


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## Bugzuki (Jan 15, 2008)

Well, I have been busy and missed this thread until now. I might have missed something in the previous discussion.

*What type of motor:* 3-phase AC induction. I think that it would be impossible for the general public to come up with the magnets needed to build DC or BLDC motors. Those magnets would have to be formed to the shape of the motor and not just cow magnets. The are other benefits also like regen.

*Mechanical brakes:* Yes. I am pretty sure that every state requires mechanical brakes on the car (State Law). The brakes could be setup to only apply after a certain amount of pedal travel and upto that point it would be all regenerative braking.

*Controller location:* Out external to the motor. This would minimize the unsprung weight and also allow the controller to be isolated from the road vibration. You would only need the three power wires and the speed sensor wires going to the wheel.

*Motor Configuration:* I was thinking that it would be cool to have a inside-out motor, but I think that it would be the lest costly to have the normal configuration with the squirrel cage on the inside. This way the rotor could have a hub mounted to the outside and the brake rotor could be mounted to that with the wheel - in the current configuration. The the brake caliper could be mounted to the stator housing.

The back side of the stator housing could be designed in a generic fashion to allow different attachments to different suspension systems.

*Suspension:* This might be an issue. If a front wheel drive car is used the rear suspension might not be strong enough to handle the acceleration forces. The do see braking force, but that is much less since the rear lifts during hard braking. The only way to find out is to try it.

*Mechanical Design:* I currently have a fully licensed version of Pro/Engineer WildFire 3.0. So, I could do a lot of the mechanical design for this project. If you guys want. I do want to inject a thought here. If someone were to have an none licensed version of some software and they used it for a project like this that software manufacturer would have the right to sue and maybe get the designs destroyed.

*Controller Design:* I have been working on a 3-Phase AC controller design - slowly. I think that the best option would be to use the Microchip controller that they have specifically designed for AC motors. I could share what I have so far.

*Something for me:* I would be willing to do this in return for your guys help getting the design together. I would probably be less inclined to contribute to this project if it had a strickly non-commercial clause. I would like to put together kits for various cars and be able to sell them.

*Manufacturing the Parts:* In order to get good deals on manufacturing it is very important to have larger quantities together in one run. If we could pull this off and have group buys that would help us lower costs.

*Education/Experience:* I have an Electrical Engineering Associates Degree(Skagit Valley College), and a Bachelor's Degree in Industrial Technology/Vehicle Design from Western Washington University. At WWU I was the Team manager for the Viking32 Government project - Natural Gas/Electric Hybrid. http://www.hybridaction.com/viking32/general.htm I then went on to be a Design Engineer, Manufacturing Engineer and Liaison Engineer for Kenworth Truck Co. (only automotive company here in Seattle). I am currently the CAD administrator for Philips Ultrasound (huge layoffs in the trucking industry last year).

I am not the best Electrical engineer, so would like help on that part of the design. I have some embedded systems programming experience, but again am far from an expert.

Hopefully we can get this project moving.
Paul


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## John (Sep 11, 2007)

3dplane said:


> No secrets. While hanging around windmill sites(web) I saw people using Fisher & Paykel washing machine motors for generator.They are basically huge outrunners. I did not really look into them but maybe you guys could do that. Criteria!: the number of arms on the stator has to be divisable by three! to make a motor for our purpose. If stator lenght(pancakeness) is not sufficient identical stators can be stacked to make a longer more powerful motor. Barna


The F & P motor I have has 42 arms. I think they also do one with 36 for their decogged motor. The magnets are I think a bit weak. The controller rectified 240v AC single-phase and then inverted it back to three phase switched positive and negative to drive the motor.


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## Bugzuki (Jan 15, 2008)

Controller idea - I was planning on having a multiple controller system as mentioned earlier. One main controller to do all of the communication with the driver and vehicle, then is sends the commands to the individual motor controllers. The motor controllers just keep track of the motor and send status reports back to the main controller.

I was designing the motor controller first with the idea that it could also act as a stand along controller - with limited driver interface (just acceleration, braking controls and status reports like speed and operating temperature ...).

With the Microchip controllers the code could be done in C so it could be edited by anyone that knows C.

I am planning for a LCD display for on the dash to give the driver the information needed about the system. I also wanted to try to tap into the instrument panel and control the tachometer, speedometer, temperature gauge and whatever else. 

If done correctly the controller would be able to control the power put to the wheels. So, if we designed the motors capable of 40 or 50KW then if you did not want all of that power you could just adjust a variable in the program to produce less. Then later if you got more batterys you could have more power. So, have a total power percentage variable that could be set at runtime. Using that Horsepower conversion from earlier, I would rather have 216 hp available when I wanted it then 100hp.


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## Bugzuki (Jan 15, 2008)

One more thing - with BLDC motors there is a larger chance of injury while assembling and disassembling the motors. The rotor really wants to be inside the stator and requires a press and a lot of care to get it out. We had to deal with that when we replaced the end cap on the Unique Mobility motor we used on Viking32.

Don't to get sued for injuries on an open source project.


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## judebert (Apr 16, 2008)

@Bugzuki: I'd love to help you out. I know C forwards, backwards, and inside-out; if you can tell me what you want the chip to do, I'll make it happen.

You're the closest thing to an electronics designer we've got so far. Madmac has some practical experience, since he is designing his own controller. 

@Madmac: If they took your design and sold it, isn't it doing what it's supposed to do? And if they're successful, it indicates a market... a market _you_ could sell to, as well. You'd be even more successful, since it's your name on the designs. If you don't have the time or inclination to fit that market, then what's your beef? Why did you put the design in the public domain in the first place?

@ALL: Someone here mentioned that BLDC motors make more torque, especially at low speeds, than ACIM. I thought the torque of an ACIM was dependent on the difference in speed between the rotating stator field and the induced field. Seems to me a controller could create a very fast rotating stator field; wouldn't that provide lots of starting torque? 

On the EVDL, someone mentioned that almost all industrial motors use the same driver card, and recommended starting with that and a small motor. Smaller electronics would be cheaper, and the controller programming could be refined at low cost. Then start scaling up to larger motors and drive electronics.

Perhaps we should split this into two threads: one for the wheel motor capable of EV propulsion, one for a general purpose ACIM/BLDC controller with EV features (like smart charging from multiple sources).


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## JRK5150 (May 18, 2008)

If we could scale a smaller design up for our needs, that would be great! I don't quite understand the process for upscaling something like this. Would we leave the same basic control program and simply scale up the power delivery section in the controller?


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## Bugzuki (Jan 15, 2008)

JRK5150 said:


> If we could scale a smaller design up for our needs, that would be great! I don't quite understand the process for upscaling something like this. Would we leave the same basic control program and simply scale up the power delivery section in the controller?


The controller would not really care or know that it was being scaled. Part of the software algorithm could include a percentage multiplier. Then it would use the full stroke of the gas pedal and downscale that to the percentage indicated. The IGBTs on the board would not have a problem delivering less power then they are rated for so they would just act as through the pedal was not depress all the way. The same for the motors - you just would not get full power.

I do not know if this ability would loose efficiency in a lower power setting - we would have to do some experimentation.


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## Bugzuki (Jan 15, 2008)

If this is going to happen we should probably organize a group. Then in that group each person should have a responsiblity to research or develope some aspect or feature.

There needs to be some controls in place inorder to come up with a quality product. Otherwise it will be a mess and nothing will happen.

Maybe we could get the forum to setup an area for this group to have private discussions that specified usernames could see. Then a thread in the Technical Discussion area that would keep everyone else upto date and give them a way to request to be on the team.

That way everything is kind of secured until we are ready to put the system in the public domain. I hate yahoo groups, so I will not go that way. I could probably setup something on my website. 

This group project was not my idea, so I am not trying to jump in and control everything but I think someone needs to lead the group.


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## Madmac (Mar 14, 2008)

Hi Judebert

Some times in this life it is worth doing things for fun and enjoyment. As the case of gas lasers for entertainment during the 1980's many of the electronics assemblies were very expensive...this partly reflected the specialised low volume market but charging over $500 for $40's of parts is excessive. As an electronics engineer it is easy to design these items. Putting the design in the public domain helps others enjoy their hobby. When a commercial company comes along uses the design (changing the product name on the LCD by editing the hex file, all menus the same including spelling mistake) and sells it as better than existing already expensive items for an ever higher price. It does not mean there is a market to sustain a business but does show that some people are greedy.
I have a business which sells products I have designed worldwide, and puts me in a position of not needing to exploit an opportunity like this.

I am designing the systems for my EV because electronics is still my hobby. Therefore happy for other individuals to make use of that work (and work of others who I have based part on) if they want to, free of charge. If nobody does that is fine. If a commercial operation wants to then they must donate funds to charity that can be publicly verified.



> Perhaps we should split this into two threads: one for the wheel motor capable of EV propulsion, one for a general purpose ACIM/BLDC controller with EV features (like smart charging from multiple sources).


A decision needs to be taken as the exact motor. I would have thought the design should be aimed at providing a low cost AC solution for as many people as possible. This allows the advantages of AC to be available to more folk. Single motor fitted to existing transmission. If this is successful then go to the next stage of in hub design.

Madmac


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## JRK5150 (May 18, 2008)

If this system could be completely scalable, we could build a simple go cart chassis as a test bed. In this way, switching or modifying test vehicles would be very easy. I think a wheel motor go cart could be a blast! I'm going out to dust off my welder!


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## Bugzuki (Jan 15, 2008)

So, if we design a motor would it all need to be designed in such a way that people could make it with a drill press, bandsaw and a welder, or do you want something the is cast, machined and ready for assembly?

As Madmac stated it would definitely be easier to design a motor to hook to the existing Transmission first and then go on to wheel motors as a second or thrid phase.

I think that a 3phase AC induction motor would be the least expensive to design and build. It would also have all of the benefits of BLDC.

It would be nice if we had a section specifically for this project then we could create another thread with voting to see what everyone wants.

I actually have a Ford Ranger Siemens 3phase AC induction motor that I was going to use as the test piece to get a controller going.


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## colhigg (Jun 28, 2008)

Hey guys, new here but love the idea. One thought I have, I use to build lots of trailers and the axles have the same lug pattern as a toyota truck. Both are straight axles and the trailer axle has nice flange for the electric brakes. I just happent to have a 89 toypta truck with bad engine:}. I just happen to be a machinst and mig tig welder with electronic hobby on the side. How about we build the hub motor onto an extra axle I happen to have. When we need to test it, we take the axle out from the truck and slide the axle under it? Let's do this and stick it to the MAN!


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## Bugzuki (Jan 15, 2008)

We do not have to make the hub motor for any specific application. The motor has to be generic. On the back side it will have a bolt pattern that an external piece can bolt to. That piece will then bolt to the suspension or axle or what ever else you can come up with. The outboard side of the rotor will have a splined shaft that a hub can slide onto with a big nut on the outside to hold it in place. The hub can then be made independently to fit any wheel bolt pattern. Or we could just pick the most common 5x114.3 and everyone can get some nice new wheels.

This setup would leave the part of figuring out the attachment to the person completing the project. This project can not have the scope large enough to create mounting fixtures - at least not until we are at the point of actually putting it on the car.

We need to start by getting a design together.

What is the formula for determining how much power a motor will create? What diameter rotor do we want? How thick should the motor be? What is the smallest size wheel that we want to support - 13", 14" ...? 

These are the type of questions we need to start focusing on.


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## Madmac (Mar 14, 2008)

> I actually have a Ford Ranger Siemens 3phase AC induction motor that I was going to use as the test piece to get a controller going.


I also bought one which is why I am developing a control system. I tried to buy an inverter but all EV companies only want to sell motor and inverter as a package. Unlike the industrial market where they are sold separately

Producing a lighter weight version of such a motor would be a good start.

Madmac


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## JRK5150 (May 18, 2008)

I agree with Bugzuki that a 3 phase induction AC motor would be simpler for the average person to build. Winding coils of wire is less difficult than machining magnets properly. Wire is also less expensive and easier to come by than neodymium magnets. It would be nice if a person could build the design at home with basic machine tools, a welder, and such, but if some pieces have to be cast, we could seek out a company that will work with us for a group buy or something to keep the costs down. I have read several people say that a BLDC controller is very similar to an AC controller so would the design of the AC control system be that much harder. If we were to start out with a single motor and conventional drive system, would we be able to simply add in the control programing for separate wheel motor control. I have a first generation Miata that I am converting. Could I pick up an industrial 3 phase AC induction motor, adapt it to my tranny, and use it as a controller test bed? If so, I would be willing to go this direction to get the controller designed, as long as it could then be adapted for wheel motor use. As for hub bolt pattern, I think using the most common bolt pattern as our standard makes sense. I would think the outer diameter of the motor would have an impact on overall torque production, so to be as universal as possible, it should have as large a diameter as practical.


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## 3dplane (Feb 27, 2008)

I'm going to have to go ahead and sort of disagree with you on that(quote from movie: office space).
If this thread is still about in wheel motors,AC induction does not stand a chance. A couple things before I go off on that. We do not machine magnets! Especially neodymiums.(it will release toxic crap to breathe if being grinded) Neodymiums are just a google search away virtually any size, shape, strenght.,and even though I haven't ordered any recently I would say about $60 worth would make a nice big motor. They don't have to be curved either.
If you have an AC induction motor use it in a conventional drive system (other than in wheel) but it is just not possible to build one in the "shed".
The only in wheel motor car I know(highway capable) that does NOT use a BLDC outrunner is the eliica(not a typo) It uses BLDC inrunners BUT it has eight of them.(8 wheeled car).And it needs the rpms to hit its top speed of 230MPH. There is a youtube video showing the machine winding the inrunner as the japanese engineers keep an eye on it and the machine screws up and brakes part of the stator.(challenging to wind inrunrunners). One more thing, it's not clear for me from previous posts but the same motor made/optimized to drive through a transmission will not work as an in wheel motor,and vica versa.They could be the same phisycal size and shape but inside two different beasts. Barna.


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## aeroscott (Jan 5, 2008)

thanks for the link on eliica , they didn't say anything about gear reduction but you could see it probably had planetary gear on it . and it was a 10,000 rpm motor .


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## 3dplane (Feb 27, 2008)

aeroscott!
No gear reduction.That was one of the main efficiency advantage Mr Shimizu was talking about in one of the videos.(there is a bunch of videos on it). I'm glad you liked it.Thanks to those uploading them. Barna


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## JRK5150 (May 18, 2008)

Ha! Great quote 3dplane, I love office space! But...you..you...you took my stapler!

Anyway, you say we wont have to machine the magnets at all to make them work. I was assuming they would have to be curved to match the contour of the can. If they don't have to be machined, I guess the BLDC is still in the race. Someone else suggested starting another thread in which a poll could be set up to vote on AC vs BLDC. Honestly, I'm still leaning in the direction of BLDC except for build simplicity. 3dplane claims a BLDC motor would be less difficult to build than an AC motor! I'm really confused! 

How about this! Next time you post, vote on your preference for AC or BLDC. This is about the biggest point of contention standing in our way at the moment. If we get this nailed down, then we can start debating the next big issue. I'm not casting a vote on this due to my own, self admitted, ignorance on the issue. So if it's agreeable to all, how about putting your vote (AC or BLDC) as the last line in your next post. 

3dplane, your info says you are in Trenton FL. I'm in Spring Hill, about an hour north of Tampa, and judebert is in Orlando. What would you say to getting together to make this happen in a group setting? I know judebert is a programmer, your a motor guy, I can do fabrication, and I have a possible lead on an electronics guy.


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## 3dplane (Feb 27, 2008)

Hey JRK!
What I meant is if you already have an AC motor and appropriate controller use it (but you can't use it in wheel). As simple as an AC induction motor seems there is a heck of a design went into the rotor and winding so the average person with basic tools can't modify it and shouldn't. I still claim that by far the easiest motor to build is BLDC outrunner! And that just happens to be the best choice for an in wheel motor as well. Read the earlier posts by gravitic anomaly. Thats a guy who designed or built(or both) a large diameter outrunner, and I've got some questions for him. I would persue to get a F&P motor and would love to tear it down and start playing with it to see how far it can be pushed but without a controller in the appropriate voltage range(and amprage) it would be pointless.So I'm back to square one no controller.Ofcourse the final design would be made available to the people who wanted to give it a whirl but I'm afraid the controller guys have to come out with a suitable product first.(hint..hint) Barna.


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## aeroscott (Jan 5, 2008)

3dplane said:


> aeroscott!
> No gear reduction.That was one of the main efficiency advantage Mr Shimizu was talking about in one of the videos.(there is a bunch of videos on it). I'm glad you liked it.Thanks to those uploading them. Barna


i think with 10,000 rpm at 200 mph it can't be direct , the planetary has a very large heavy cap , eliica had what looked like one . the planetary is 95% or better eff.


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## Bugzuki (Jan 15, 2008)

I would learn toward believing that a planetary gear set in the motor would allow for better effiency. 

BLDC or AC pro/cons (please correct me if I am wrong), 

BLDC Pros

simple controller design and alogrhythm due to the constant magnetic flux in the rotor.
high efficiency
long life - no rubbing parts
Cons

High motor cost due to quality magnets
Poteintial of injury during assembly
AC Induction Pros

Simple motor design
High efficiency
Long Life
Cons

more complex and costly controller and algorhythm
I have not decided at this point if it would be better to have an inboard or outboard rotor. The outboard rotor would have more rotating mass and would cut down on the space to mount the brake calipers.

If someone could find an inexpensive sorce of molded Neodynium magnets I would be interested in looking into BLDC - otherwise I would have to go with AC induction with an inboard rotor (don't know if outboard would work on AC induction). Can magnets similar to these be used in BLDC motors? http://www.emovendo.net/magnets/motor-magnets/ just larger


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## Bugzuki (Jan 15, 2008)

I guess to get around the injury potential of BLDC motors we could design the motor to be assembly with the magnets going in last.

That way the rotor and stator could be assembled together then the magnets slid into place and locked with a retaining ring. Then if disassembly was required the magnets could be removed first.

Edit - Now I have probably defeated any arguement I had for using AC induction - except that I have one.


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## colhigg (Jun 28, 2008)

AC or DC does not matter to me guys. I just want to get started. I need to know the first thing I can do on this. I am going to go ahead I guess and machine a plate for the axle and hub I have so it will fit inside the wheel. Just somewhere to start. I know a lttle bit about electronics and have fooled around with the basic stamp controller if that helps. I will be able to monitor the rpms on the wheel to maybe control the voltage or freq or something. You all tell me. I will figure out how to post picture here.


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## judebert (Apr 16, 2008)

There's a post on the EVDL including opinion on where to start and some sources for possible controller components. One of the components even includes source code. http://www.diyelectriccar.com/forums/showthread.php?t=15523


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## Madmac (Mar 14, 2008)

There are quite a few sources of open code for driving ACIM's, most are semiconductor companies application notes. They lack a number of features for EV use ( including the Circuit Cellar design), regeneration, traction control, safety management as well as limiting speed when motor is in reverse. 

The easiest to implement initially is volt/hertz control. When the hardware is debugged vector control can be implemented. The Microchip dsPic's are underpowered to do a good implementation, but with all the open code they are the easiest to get working. Then it is time to upgrade to a much faster processor to add some better features.

If you have a Ford Siemens motor remember to change the bearings for sealed lubricated ones.

Many control details have been already listed in this thread
http://www.diyelectriccar.com/forum...ilt-ac-alternating-current-systems-10402.html

Madmac


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## cpt_caveman (Jun 30, 2008)

Hi Allow myself to introduce...myself. 
I'm cpt_caveman, and I'm currently an Electrical Engineering grad student. After my undergrad I worked in the industry for 7 years. I built a PMDC controller as a research project in the past. I'm currently looking at building a induction machine controller. I would like to help out with the project. 

I see that there still is some disagreement over which machine to use. That's fine the controller hardware for PMDC and induction machines is very similar. I see that there are a few programmers willing to help out, that's great. Perhaps we should build a universal controller hardware platform and the software could be modified to suit a PMDC or induction machine. If someone wanted to have one motor and bolt it to the clutch plate, or 4 motors in each wheel they could do so. 
I personally think that 4 motors would be awesome, with a central controller adjusting for cornering, yaw rate etc. I also realize that it is practical to start with only one motor and test it. 
The only decision that needs to be made is: what is the maximum power this controller needs to put out?


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## OHM (Jun 30, 2008)

Im going to take a back flip and suggest building it like the Gemini Electric Motor 
which will make it efficient, cheap and easy to build for everyone which was the 
main aim for this project. The Gemini motor can be built by almost anyone it just 
doesnt have a suitable controller in the market. Mr Ettridge has expressed he is
also open to help anyone who isnt going to market his invention in supplying info
on how to build one for their own use.
http://www.geminielectricmotor.com/



















The other thing that could be considered could be a custom big power DC hub motor 
for big chopper style bikes with big rubber, it would help change the minds of these 
cavemen and bring a whole lot of other want to be bikers out of the woodwork.
Also the big fat diameter tire will help with the starting torque and there will be more
room for batteries in the frame.
It would also help the many dozens of custom home and retail reverse trikes out there.
This is a very big market.


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## JRK5150 (May 18, 2008)

I read the EVDL link judebert provided and found that the book "Motor control electronics handbook" by Richard Valentine supposedly has enough info in it for someone to build an AC controller. I suggest that we get this book, build that controller design, and use that as the basis for our main controller.

Would it be possible to design this main controller to power several different configurations? For instance, a single motor, or two wheel motors, or all four wheel motors. If this were possible, we could start with a single motor to nail down the basic control. We could then move to two rear wheels, as they would probably be the least complicated (no steering). Then finally, move to all four wheels. 

As has been suggested before, I propose we use a main controller for all the basic control programming and separate wheel controllers for multi-motor setups. I further suggest that we mount the wheel controller to the chassis and not to the wheel itself in an effort to increase durability. This separate wheel controller could be developed after we have a working main controller. The wheel controller could take the main control input and compare that with wheel speed, directional inputs, and input from the other wheels to arrive at the final drive signal. This is where our ABS, traction control, anti-skid, etc. would come in. We could have either one centralized wheel control system, possibly integrated with the main controller, or we could have separate wheel controllers for each wheel.


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## Bugzuki (Jan 15, 2008)

What ever way you look at it there would need to be a set of IGBTs for each motor. Otherwise all of the motors would turn at the same speed all of the time. Which probably would work, but would not be optimal.

I agree we need to start and get a controller working on one motor and move on from there.

I am planning on moving forward with the AC inductive design I already started on. Then it could be edited to run a BLDC motor if wanted.

All OEMs that run electric motors use AC induction - must be something to that. Probably less expensive to manufacture once the controller is designed.


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## Madmac (Mar 14, 2008)

I believe that the book was written in the mid nineties which means the design probably dates from the early nineties. A lot has changed in the last 18 years and would suspect that some of the parts are now EOL (end of life).

I seem to remember reading that it used a MC68000 processor with code provided in assembler. That CPU needs a lot of support devices and compared to modern SOC (system on a chip) systems would be a lot bulker, more expensive to build and more difficult to get a layout that is noise resistant. Also the PWM speed is probably fairly low ( have not seen any information on this design, If anyone has bought the book maybe they can fill in the detail).

I would recommend the Microchip dsPIC based design modified and presented in Circuit cellar. Max power is 400 Amps at up to 600 Volts - 100KW. It does need quite a bit of extra design work and the code needs a lot of change. The hardware is straight forward, compact and low'sh cost. It will not have the grunt to do an all singing controller but more than enough to do the same functions as commercial units.

Madmac


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## judebert (Apr 16, 2008)

Microchip document AN908 describes a flux vector controller with full source code. AN1162 describes a sensorless version. They even have prebuilt boards with power stage plugin modules to run a 3/4HP motor.

I've looked at some of their source; what I saw was very clean and professional. It's been debugged, which is useful. The only problem I can see is that the input is a single toggle switch, which goes between 50% and 100% output. To have a useful EV controller, we'd need to change that to a proportional throttle input.

The source would not be too difficult to modify; there's plenty of space left, plenty of free processor time, and several free pins (including at least one ADC channel). 

I'd prefer to start with the closed loop version. With that as our launching point, an ACIM controller would be easy to program. The only thing standing in the way is the need for a C compiler. Or my willingness to translate all that C to assembler.

I can't find the CircuitCellar design online. Does it include source?


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## cpt_caveman (Jun 30, 2008)

Just to back up what Bugzuki said, it would not be practical to have one controller box control one to four motors. Depending which control scheme you need you may need to sense the phase, stator current and speed of each motor. The best idea would be to build one controller, test it on one motor, and if you wish to have a motor at each separate wheel you can build four copies of the controller. Once you can build the controller, it would be easy to make 3 copies of it. I also agree that it would be best for everyone if we got a simple controller working, with a few safety features and lots of free ports so people could adapt it to their needs. If you look at Cafe Electric's Zilla motor controller, it doesn't have inputs for all the different sensors. It has a separate board which takes in a bunch of different inputs and packs all this information together on a CAT5 cable and sends that to the main controller. If I were going to build a traction control system that's what I would do. Have a central unit sending a torque command to each wheel's motor controller over some CAT5 cable in serial form. 
I am not a big fan of PIC controllers. I suggest we use the Atmel series. There is another forum here, (cheap controller I think) where people made a DC motor controller. A lot of them were using the Atmel Mega8. The mega8 is underpowered to do a serious AC motor controls but the AT32UC3 would be great, it's cheap and powerful. Also all the software is free. 

Who wants to take some ownership here?


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## Madmac (Mar 14, 2008)

> I can't find the CircuitCellar design online. Does it include source?



http://www.circuitcellar.com/microchip2007/winners/MT2291.html

It is basicly the microchip code but with some interface changes.

Madmac


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## JRK5150 (May 18, 2008)

Please excuse my blatant n00bishness, but I was just reading the home built AC systems thread and ran upon what I consider to be a great idea. Maybe this has been suggested and I didn't understand or this idea won't work, but check out etischer's idea post #113 on page 12 of that thread. He seems to be using a very small AC controller as the brains for his system and a set of 6 IGBTs as the muscle. 

Could we simply find an appropriate AC controller, such as an RC car setup, and use it as the brain to control a similar IGBT pack? 

Again, pardon my ignorance on this matter, but it seems too cheap and simple not to bring up!


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## Madmac (Mar 14, 2008)

Using a high power off the shelf inverter has been used by a number of people on the EV Album site. The disadvantage of those is they are air cooled and quite bulky. Could be rebuilt as water cooled.

Using a low power inverter and then adding the parts to drive a large output stage is more difficult. The gate drivers will not have enough current rating. the current sensors will need changing. The DC rail decoupling will need improving, the overcurrent protection will need modifying as well as adding open circuit pot disable and high input lockout. Most companies seem to base their inverter range on either two versions of PCB low and high power or two PCB, control and driver interface.

Like many of these approaches you may get it working but with a poorly modified design that is stressing parts, failure will occur but only after a period of use. If you have the expertise to do the changes correctly it is no more difficult to design what you want. Doing a design from scratch or modifying the layout of high power inverter (if you have a good idea of the electronic implications or keep changes to minimum ) are much more likely to result in a reliable system.

Madmac


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## Bugzuki (Jan 15, 2008)

I think that it might be best to have two processors in the control system. One that is a Motor Control specific processor and the other a general purpose processor. 


The General purpose processor could do things like update and LCD screen, check temp sensors, turn on coolant pump, send output to gauges, communicate with the Car PC/laptop to update the firmware and send datalogging information and so on.
The motor controller would collect input from the throttle and control pots and determine what the motor output should be or if it should be in regen mode.
Then the two processors would have constant comunication on the status of the motor and system.
I think that it would be sweet to have an OBDII system build in to try and hold to the automotive standards. We would definitely need to have everything communicate over a CAN network since that is currently the industry standard. I also thing that every connector needs to be automotive quality - and not (no offense) CAT5 cables...


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## Telco (Jun 28, 2008)

Hi, new member here, was directed here from another site to interface with the Supreme Being, Hi Torque Electric. All hail Jim. 

Anyhoo, after reading this thread, thought I'd throw a little brainfood in. 

********************************************************
I once wrecked a car. I was driving along, had to take a 130 angle degree turn on a hill in the city in the winter with the apex of the turn on the downhill side. On this turn you are going downhill on the approach and uphill on the departure. I hit a patch of ice almost into the apex of the turn while going 15MPH in a Nissan Sentra, 2 feet from the curb, and still hit hard enough to bend the 20 pound wheel. This is something you need to consider about the wheel motor, being unsprung weight it will take the DIRECT impact. 

Being a heavy piece that doesn't move when you hit a curb, and considering that by putting a hub wheel out there you don't have nearly as much supporting hardware, you will be bending suspension pieces with a simple 15MPH hit. Since the hub motor isn't designed to take side impacts, the hit may be enough to drive the rotor into the hub hard enough to damage parts. Now all I had to do with the Sentra was change the tire and drive on, but for this you'd be looking at major suspension work after a tow home, with a possible motor replacement. 

Also, being a heavy piece, the suspension will need to be built up. Otherwise, hitting a pot hole might actually bounce the wheel off the ground, causing possible damage. This will also cause a worse ride on the vehicle. Consider the effects putting 20 inch wheels on a car that came with 15s does. 

Now consider that the guys selling hub mounted motors are SELLING HUB MOUNTED MOTORS! If you damage one, they get to sell another motor. Does it matter to them that the design of their motor invites damage during normal use? Nope, because they are selling motors and the damage means they can sell MORE motors. Just because one design is the most efficient doesn't mean it's the best, the environment in which it's used makes a difference too.

*******************************************************
Second, on the legalese: You definitely want to check with an IP lawyer on this. Sure, you want it to be open source, but you should really consider checking on what needs to be done to protect this. Otherwise, some greedy stinking SOB might come across this about the time you finish the product. He checks and sees that this is not protected in any way, so he takes the designs straight off this board and to the patent office, then starts selling them. Now he's got your IP and can sue you to make you stop working on your own development! Sure, you can fight it in court, but in the meantime he's selling your designs and using the profits from that theft to pay for the lawyers he's suing you with. Even if you fight it, it can take years and tens of thousands with no guarantee that you'd be able to get anything from it.

Other than that, good luck with this project.


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## judebert (Apr 16, 2008)

Telco said:


> Second, on the legalese: You definitely want to check with an IP lawyer on this. ...some greedy stinking SOB ... takes the designs straight off this board and to the patent office, then starts selling them. Now he's got your IP and can sue you to make you stop working on your own development!


We've been talking a little about this; personally, I don't care if he sells them, while others have different views. But he can't patent it, because it's "prior art" when he finds it online. Additionally, it's copyrighted the moment we make it, so we could sue _him_ for infringing on our copyright. As long as we publish it online with a date stamp, and specify "(c)2008 Judebert", it won't take even *seconds* to get any IP case against us thrown out of court. 

If we use some well-defined license, such as the GPL or any CC license, we get a debugged license that's been useful in real life already. The only real problem is who owns the license; we would probably wind up with code copyright by Judebert, controller design copyrighted partly by MadMac and partly by bugzuki, and motor design copyright by who-knows-how-many people. 

The only way around that is to specify a license that will be used for any of your contributions; that way we can guarantee that all the other contributions can be used together. In my case, _*anything I contribute here can be used under the terms of the GPL v2.0 or later*_, unless otherwise specified. 

If we ever get anything accomplished, we might want to consider setting up a foundation to hold the copyrights, so anyone who's interested can negotiate with a single entity.

To get back entirely on topic: I checked out the Atmel and Arduino. I'm less than impressed; the Microchip has all the pieces required for the controller brains, while the Arduino would likely need additional peripherals. The Arduino built-in PWM is only 490Hz, for heaven's sake! The dsPIC30F6010A can do ACIM control at 20KHz (more than 40 times as fast) with 2/3 of the CPU time left over. 

I did like the Arduino free development tools. But I think the Microchip dsPICs will work with the PIC18F GNU tool chain. I'm still checking on that, though. Worst case, I have to program the whole thing in assembly (the Microchip assembler is free).


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## Madmac (Mar 14, 2008)

for those interested in motor design have a look at

http://www.osti.gov/bridge/servlets/purl/921776-92UEt1/921776.PDF

The estimated cost on page 85 is interesting

Madmac


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## Bugzuki (Jan 15, 2008)

I might as well be the first to take the plunge and post up what I have.

Here is a screen shot of the controller design I have so far. I was planning on using a battery voltage in the 300-350v range.

Components used are: (incase you can not read it)

Microchip dsPIC30F6010A - Motor Control Processor
Fairchild Semiconductor FAN7382N - High/Low side Gate Driver
Fairchild Semiconductor FMG2G400LS600 - IGBT Power Module (not shown)
National Semiconductor LM1084IT-5.0 - 5V 5amp Voltage Regulator
Micorchip MCP2551-I/P - CAN Transceiver - PDIP package
Silicon Labs CP2102 - USB to Serial (UART) Bridge
Lambda PAF600F280-12 - DC-DC converter 200-400V input 7.2-14.4V output (not shown)
Throttle and Brake Potentiometers (not placed yet)









Click this one for a larger image:
http://www.hybridaction.com/images/Drive System/schematic.jpg

©* 2008 Paul Wyndham (Bugzuki)*
*Under the terms of the GPL v2.0 or later*


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## Bugzuki (Jan 15, 2008)

Madmac said:


> for those interested in motor design have a look at
> http://www.osti.gov/bridge/servlets/purl/921776-92UEt1/921776.PDF
> The estimated cost on page 85 is interesting
> Madmac


That shows exactly what I thought, none of the current manufacturers are setup to produce in quantity, so they have to charge outrageous prices to make money. according to that page if they manufactured 100K of the motors @ $399.60 that would cost them 40 million dollars. So, no one seems to be willing to take the leep. But, if the did make the motors I am sure they would be able to sell them real quick even if they did charge 500 buck each or even a 1000. 

It all goes back to supply and demand, they do not see the demand so they are not going to take the risk to supply.

That is why this project is so important. There needs to be an option for people to get better technology then brushed DC at a price they can afford - or be able to build over time as they have the funding for the components.


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## JusSumguy (May 19, 2008)

judebert said:


> I always thought it would be interesting to put magnets in the rotor, and outfit the calipers with windings. You could get propulsion, regen, and friction braking all in the same place.


WOW.... I like this.



JRK5150 said:


> Next, I think we should make sure that we do NOT infringe on any patents. To this end, I suggest keeping this as simple as possible. We can get fancy later. Getting sued developing a free drive system would severely suck!


Can't be sued for open source. You can rip off anybody's patent for your own use. The patent only protects you against sales competition.

Open source is free. Anybody's idea is on the table.


---


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## Bugzuki (Jan 15, 2008)

Here is my sketch of the system that shows more.

http://www.hybridaction.com/images/Drive%20System/IMCM.jpg

I put it in as a link because it is big and does not fit the forum very well.

©* 2008 Paul Wyndham (Bugzuki)*
*Under the terms of the GPL v2.0 or later*


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## judebert (Apr 16, 2008)

Bugzuki,

Liking it! Lots of pins left on the chip, which leaves plenty of space for interoperability and additional functionality. I have no doubt that this will fit your needs very nicely.

A few questions, if you don't mind.

It looks like you're controlling your three phases individually with PWM outputs from the chip. I suppose these will be offset by 120* in the software, as opposed to using capacitors or something in the hardware? (I like that, incidentally; I just want to make sure I know what's going on.) (Edit: Of course they need to be controlled individually. That's the whole idea behind flux vector control. Duh. Can we just assume I never exposed my ignorance by asking this question? Thanks.)

I notice in the sketch that the chip controls the water pump. Why in the world? Are we expecting the pump to behave differently depending on some control input or condition?

I was expecting an LCD for configuration and status display. I think the USB control is probably better, but it does require a computer. There's an Ethernet library for the PIC family; we might want to consider that instead.

I don't know anything about CAN bus, beyond the fact that it's a way for automotive peripherals to communicate. Is the idea to use CAN for configuration, or for driving gauges, or something else?

Not knowing anything about electronics, really, I have to ask how this design functions in reverse, for regeneration and charging. How would the programming be expected to handle full batteries, or high currents, for instance? 

What do you expect the "Mode Selection Switch" in the sketch to do? Since I'm expecting all the configuration to be done through LCD, CAN or USB, I imagine it would allow us to switch between "race", "commute", and "valet" presets. 

And finally, the big one for me: I can't fit 300+V of batteries in my car. I was lucky to fit 144V. I've heard of a "buck converter", although to me it's just a black box full of magic that converts small voltages to higher ones (I am sophisticated enough to realize that this means a corresponding tradeoff in current, at least). What would be required to make this controller work with lower voltage packs? How low could the voltage go and still support readily available inverter-rated ACIMs?


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## cpt_caveman (Jun 30, 2008)

judebert your comparison of the dsPIC30 to the Atmega168 used in Arduino, was hardly fair. The dsPIC30 can run up to 160MHz while the Atmega168 can only go up to 16MHz. However everyone here seems to be comfortable with the PIC family so I won't preach the benefits of Atmel any longer. You won't have to write the whole thing in assembly there are compliers available. 
Also the buck goes from a higher voltage input to a lower voltage output, you are thinking of the boost converter, which goes from a low voltage to a higher voltage. 

The schematics that Bugzuki put up are a great start you might want to add in some temperature sensing and DC bus voltage sensing so the controller can protect it's self and the motor.


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## judebert (Apr 16, 2008)

cpt_caveman said:


> judebert your comparison of the dsPIC30 to the Atmega168 used in Arduino, was hardly fair. The dsPIC30 can run up to 160MHz while the Atmega168 can only go up to 16MHz.


Sorry; I wasn't trying to be unfair or cast aspersions on anyone's favorite platform. The Arduino is used on many projects on hackaday.com, and I know it's a flexible, open board facilitating rapid development. I was only comparing the available documentation, since I know so little about either solution. From what I could find, it didn't look like the Atmel was going to fill our requirements. I'm still open to other suggestions, and I'll still stand by my offer to provide (under the terms of the GPL) the programming for anyone who's building an openly available EV-capable controller. 



cpt_caveman said:


> However everyone here seems to be comfortable with the PIC family so I won't preach the benefits of Atmel any longer. You won't have to write the whole thing in assembly there are compliers available.


Just call me the human compiler!  Actually, I'm finding that there is a GNU toolchain for the PICs, too. My intent is to build a set of pseudocode algorithms that describe a set of controllers (including ACIM, BLDC, flux vector, volts/hertz, and open and closed loops) then translate them into whatever language is necessary. The pseudocode will likely be very C-like.

Assembly isn't that hard. Especially from the level of C. I expect a good deal of time, but not too much stumbling.



cpt_caveman said:


> Also the buck goes from a higher voltage input to a lower voltage output, you are thinking of the boost converter, which goes from a low voltage to a higher voltage.


Whoops. Thanks!



cpt_caveman said:


> The schematics that Bugzuki put up are a great start you might want to add in some temperature sensing and DC bus voltage sensing so the controller can protect it's self and the motor.


Agreed. I've seen MadMac make similar comments on other threads; I assume his controller schematics will include these features. Even if he's not ready to release yet, I expect he'll be commenting soon. <hint, hint>


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## cpt_caveman (Jun 30, 2008)

yeah the Arduino is kind of a platform for non engineers, or people who don't want to get their hands dirty. The software platform for Arduino is based off of this tool called "Processing" that was developed for artists to be able to program. I wouldn't try to do an AC motor controller with this platform. However Atmel has lots of free and easy to use tools, and a huge open source community. Here are some application notes from Atmel on how to use some of their other controllers for PMDC, and simple induction machine V/Hz control. It might be worth looking at. 
http://www.atmel.com/products/AVR/mc/?family_id=607
If you wanted to go beyond V/Hz control and do something like torque control you would need something with a little more power, then you would be approaching something comparable to the dsPIC.


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## Bugzuki (Jan 15, 2008)

I was planning to have a second controller do things like run and LCD screen and run the gauges. That is why I did not include those things in that schematic.

I have not finished the schematic that is why there is not a battery sensor and the other things that are missing. I kind of got stuck - Like I said I am not an expert in electronics.

I was thinking the mode select switch would be if you were running with a single controller of two. If you were running two I would have the all of the sensors, actuators and extra stuff run off the add on module. While, the motor control would run off the motor control module. This way the system could be tested with one controller and then the second could be added later. Or if you did not have the money at first you could start out with the base system and add more at a later time.

For the addon controller we could use any thing - it would probably be great to use an Atmel controller. But, for the motor controller I think that we need to use the dsPIC since it is designed specifically for motor control and has the functionallity built in.

The 6 ports I picked on the controller for the IGBT drivers are the PWM high and low ports specified for the three IGBT, and, yes, they would be driven independently.

The DC-DC converter that I specified is for voltages between 200 and 400 volts. But that could be switched out for a different converter if you have a different pack voltage. I just found the PH600 280-5 series converter from Lamdba that might have models for lower input ranges (looks like on option is 82-185 Volts): http://www.lambdapower.com/products/ph-series-sf.htm

The controller would not really care what the pack voltage was as long as a variable was set so that the output could be varied in the range available. The motor would probably have to have a different winding setup to have different voltages (wire size and number of turns).

Sorry I did not put quotes in, but I am tired.
Paul


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## Bugzuki (Jan 15, 2008)

The CAN controller would be used for the motor controller to speak to the add on controller or any other device we choose to install like the battery control module.

The USB port would be used for firmware updates and maybe data logging to another PC. I guess the usb port could be switched out for an ethernet port, but I do not understand how that would work. So, I thought that a USB connection would be best. It deffinitely would need to be a wired connection if we did go ethernet - otherwise someone might figure out how to hack into the control program. As it would be open source.


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## Telco (Jun 28, 2008)

Hey, one thing you might add onto the controller is a way to turn on a generator, seeing as some people use tow-behind range extenders. It would need to be able to turn on and off a generator based on the battery load, so as to only run the generator when the batteries are low, then shut off when they are charged up. Doing it this way would let the generator only run max out or not at all for best efficiency, and would allow unmonitored recharging while the driver is making a pit stop. It would also need to be able to handle different battery types, seeing as different types require different recharge methods, ie using a lead acid recharge method would cook an AGM.

Unfortunately, ideas is all I can contribute .


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## Bugzuki (Jan 15, 2008)

Telco said:


> Hey, one thing you might add onto the controller is a way to turn on a generator, seeing as some people use tow-behind range extenders. It would need to be able to turn on and off a generator based on the battery load, so as to only run the generator when the batteries are low, then shut off when they are charged up. Doing it this way would let the generator only run max out or not at all for best efficiency, and would allow unmonitored recharging while the driver is making a pit stop. It would also need to be able to handle different battery types, seeing as different types require different recharge methods, ie using a lead acid recharge method would cook an AGM.
> 
> Unfortunately, ideas is all I can contribute .


That is a great idea. I think that it would be best suited for the addon controller, and not necessarily the motor controller.

Keep the suggestions coming. Some one should go through this thread and compile a list of options people want. Then when someone thinks of another they can just quote the list and add their thoughts. Then we can remember them and add them if feasible. I'll do it if I have time.

Happy 4th of July everyone.


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## Csnead (Mar 29, 2008)

Hello Everyone
I am Located in Tampa Fl and have an Interest in Building a BLDC Motor Controller and Motor. I work in the Industrial Electronic Motor Controls area up to 2000HP every Day. I have 6 each 200 AMP IGBT'S, some 400VDC Filter Capacitors, Heat Sinks and a Gate Driver Board that I could use to Build a Power Section and perform the needed Testing for the MicroBoard with Software.. I would need to Reverse Engineer the Gate Driver Board, because the Normal Input Voltage is 650 VDC. I may need Help Re-Designing the on-Board Switching Power Supply for the Low Voltage Electronic Circuit needs which probably means Designing a New Gate Driver Board. Will this Help The Project? Who should I contact? Sincerely Chuck


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## 3dplane (Feb 27, 2008)

While we are at "don't forget this" I just thought about reversability for the hub motor application.Not an issue for transmission mounted motor.(it would suck to crawl under the car to reverse two out of three wires on all motors to back up and do it again to go foreward LOL) Barna


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## Madmac (Mar 14, 2008)

Bugzuki
The FAN7382 is not a good choice of gate driver for something of this power. 350mA source / 650mA sink is low compared to the 6 Amps+ needed to switch fast. Also no desat protection to protect the IGBTs in case of shorts. Opto isolation to limit interference being coupled back to drive board will make life easier. Interference at this power level gets everywhere.

judeburt


> I don't know anything about CAN bus, beyond the fact that it's a way for automotive peripherals to communicate. Is the idea to use CAN for configuration, or for driving gauges, or something else?


It is a physical layer for serial communication that is very noise resistant with built in hardware for high priority messages getting delivered first. Can be used to send any payload package of small packets. There is a data structure used in the automotive world, does not need to comply with this.



> Not knowing anything about electronics, really, I have to ask how this design functions in reverse, for regeneration and charging. How would the programming be expected to handle full batteries, or high currents, for instance?


Regeneration is simple in theory, just specify a negative torque. Very difficult to get info on how to do control loop to regulate voltage being generated. Trying to work thru maths but not easy....currently looking for inspiration on this (or build prototype and measure what happens)



> What would be required to make this controller work with lower voltage packs? How low could the voltage go and still support readily available inverter-rated ACIMs?


Rewire standard motor to get at both ends of coils and this drops voltage by approx .6. Any lower and motor would need to be wound for voltage. A boost converter could be used and these can run at 95%+ efficiency. Remember half the current double the voltage give the same watt hours so more smaller batteries may be the solution.

cpt_caveman
Atmel make good products, just used one of their new 32 bit devices in a product....cool CPU. With the Microchip device there is a lot of code in the public domain so why reinvent the wheel. Does have limitations if things like traction control are wanted as there is not a lot of spare mips

judebert



> Actually, I'm finding that there is a GNU toolchain for the PICs, too.


The ideal would be to convert the code modified by the circuit cellar group to be compiled using the GNU tool chain

csnead


> I may need Help Re-Designing the on-Board Switching Power Supply for the Low Voltage Electronic Circuit needs which probably means Designing a New Gate Driver Board


.

Probably easier to redesign both. The gate drive is the most critical analog part of the design and not that expensive in parts.
The IGBT and filter caps will save you quite a bit of cost. (good quality high ripple current caps cost over $40 each in small quantities)

3dplane


> (it would suck to crawl under the car to reverse two out of three wires on all motors to back up and do it again to go foreward LOL)


Reverse is just a few lines of code plus a control input. The software can also scale the accelerator input to limit the max speed to safe level.


Madmac


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## Madmac (Mar 14, 2008)

Another document on PM motor design. One option is to slide magnets into rotor to fix in place.

http://www.ornl.gov/~webworks/cppr/y2001/rpt/121559.pdf

Madmac


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## Bugzuki (Jan 15, 2008)

Madmac said:


> Bugzuki
> The FAN7382 is not a good choice of gate driver for something of this power. 350mA source / 650mA sink is low compared to the 6 Amps+ needed to switch fast. Also no desat protection to protect the IGBTs in case of shorts. Opto isolation to limit interference being coupled back to drive board will make life easier. Interference at this power level gets everywhere.


When looking at the data sheets what parameter do you look at to see what the source/sink amperage needs to be to handle a certain output frequency? The FAN7382 data sheet says that it is capable of motor control, but maybe that is lower speed then we would want (10,000 RPM).

Madmac - or anyone, can you explain this to me a little better?

What driver would you suggest? The drivers in the circuitcellar article look really big and complicated, but if that is what we need the that is what we need.

What is "desat"?

I knew that we would need opto Isolation, but had not gotten there yet. I was looking at chips, but that is all the farther I got.


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## manic_monkey (Jun 24, 2008)

This thread seems to be getting repeatedly side tracked into controller design. I thought this was supposed to be about designing a hub motor?

It seems like most of the effort is going into designing a controller for a motor that doest yet exist, for a drive system that hasnt yet been finalised. 

assuming the plan is still to create a BLDC outrunner motor, i would forget about the controller untill at the minimum the follwing can be decided upon

1. motor type. (axial vs radial) 
2. overall motor dimensions
3. shaft dimension (how much torque is going to be going through this thing?, how long does it need to be)
3. stator dimensions
4. stator laminate thickness
5. wire swg, number of turns
6. wiring schemas 
7. feedback (hall sensors?, number of, mounting locations)
8. magnet type / size / number / placement ( even the thickness of backing metal to close the magnet loop vs halbach array discussion)
9. VERY IMPORTANT - costing and sourcing of materials. have you tried to buy small amounts of silicon steel? isnt easy


maybe its time to split this into two threads?


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## judebert (Apr 16, 2008)

manic_monkey said:


> assuming the plan is still to create a BLDC outrunner motor, i would forget about the controller untill at the minimum the follwing can be decided upon


But, none of those things necessarily impacts the controller design. We intend to program the controller to handle BLDC and ACIM (since they're so close in control, anyway; all that needs to be changed is the calculation for the rotor flux), and to work with either closed-loop or open-loop systems. As long as we also allow the user to define max voltage, current, and motor parameters, we should be able to design a controller for any motor. (We might need different power stages, but bugzilla and MadMac are dealing with that already.)

It's not our fault that the controller guys have been cooperating better than the motor guys. 

I'd love to split into two threads. It would make things a little easier to keep track of.


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## Bugzuki (Jan 15, 2008)

I understand the need to get a motor design going, but at the same time think that the controller design is more important to have working first. Here is my reasoning.

1. There are a couple of us that already have AC induction motors so these motors can be used to test the controller.

2. Nobody seems to have a spare controller that can handle both AC and BLDC motors, so if we did come up with a motor design we would have no way of testing it. Then we would have to set it aside and design a controller. 

Since the controller is an essential part of the motor - I feel that it is at this point more important to focus the main attention on getting a working controller. Besides it seems that everyone has a different idea in what they want the motor to do. If we can get experience with the controller - which is configurable - then maybe we can make a better motor design -which is more unforgiving when it comes to paying for prototypes.


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## manic_monkey (Jun 24, 2008)

Bugzuki said:


> 1. There are a couple of us that already have AC induction motors so these motors can be used to test the controller.


this is true, but also some have controllers already that can be used to test the motor



Bugzuki said:


> 2. Nobody seems to have a spare controller that can handle both AC and BLDC motors, so if we did come up with a motor design we would have no way of testing it. Then we would have to set it aside and design a controller.


I think you have just highlighted my issue - no one seems to know wether they want BLDC or AC motor, or its specifications. I dont think the correct solution to not knowing these things is to create a controller to handle both. My first programming job was as a realtime embeded software developer (PLC's and telemtry control systems) and not having a very defined spec is generally suicide. 

I understand your points though, and if the controller is to take lead in the development process I think some hard limits need to be put on it. 'Scope creep' really is the enemy of any project, and this is multiplied many times when the project is open sourced and has many contributers.

I think that things like traction control, 2 wheel or 4 wheel drive control, active differential, communicating via CAN - should all be put on the back burner, and focus on controlling a single motor, and doing it well. to be perfectly honest, the process of controlling a motor using a microcontroller is fairly trivial. The methods of control - such as space vector modulation are well understood and documented. Debugged algorithms and code are available, and there is a wealth of similar control circuits to choose from (I believe the power section is just a class D amplifier). All these other things are nice extra's, but they are just that - extra's.

In not saying developing an uber controller isnt a good idea, it is. Just one step at a time.


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## Marc1 (Jul 7, 2008)

Hi there!
I am a complete novice on this topic and I am trying to familiarize myself with all it's needed for a EV conversion.

On the subject of wheel motors, I always thought that if electric cars had undergone the 50 years of development they missed out on, we would now have special wheel motors super light, waterproof, with built in brakes and regenerative braking thrown in. As it is today, to achieve that in a DIY environment would be a rather steep road.

Has anyone thought of a motor with two shafts, independent from each other, to be placed in stead of the diff, on an independent suspension either front or back? It would allow for differential revs at time of turning, and will not be suspended. I know that it is probably not easy to build but the only difference from a conventional motor is the need for an internal central bearing or a larger double bearing each side, allowing each shaft end to cantilever. Probably easier than a wheel motor.


​


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## OHM (Jun 30, 2008)

Everyone should focus on the motor design.

There are plenty of affordable controllers
but no affordable AC or brushless DC motors for a larger EV!!!

We need a big affordable Hub motor not controller.


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## Bugzuki (Jan 15, 2008)

Okay, Lets try it this way.

What size wheel should the motor fit in?
(just quote and put your name in where you vote)

13 inch
1.
2.
3.
4.
5.

14 inch
1.
2.
3.
4.
5.

15 inch
1. Bugzuki
2.
3.
4.
5.

16 inch
1.
2.
3.
4.
5.


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## Bugzuki (Jan 15, 2008)

What motor setup do you want?

Brushless DC - Inrunner
1.
2.
3.
4.
5.

Brushless DC - Outrunner
1. 
2.
3.
4.
5.

AC Induction - Inrunner
1. Bugzuki
2.
3.
4.
5.


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## Bugzuki (Jan 15, 2008)

I think that all of the other question Manic_Monkey stated in post #165 are important, but more technical so they need to be discussed in more detail after we get these two decided on.

I still think that the controller could be developed now since it can be ported to either one of the motor configurations. But, lets get started on the hub motor design - since everyone seems to want a hub motor.


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## manic_monkey (Jun 24, 2008)

I think 13-17" wheels are probably the most common sizes found, so the motor should really be able to function adequately through that range. I would say design it for a 15", the middle ground. that way it should have enough torque for 17's, and with a little thought it could be made physically small enough to fit 13's

as for motor type - I was almost sold on the idea of BLDC, but now im heavily in favour of AC. I just dont see any advantage in choosing BLDC

A BLDC will require just as much work to make as an AC motor, but includes the extra cost of neodymium magnets. for the size of motor were on about, thats a lot of big magents, which means a lot of money, and presents difficulty in assembly. (i have some 2cm thick neodymiums and their a bitch - i keep them in seperate rooms ever since i wasnt paying attention once and they snapped together)

Ive never seen an AC outrunner though. My guess is that it would work, but thats just a guess. i dont think theres any real point in designing an inrunner though when you can already buy normal AC motors off the shelf

what about discussion on axial vs radial motor designs? I normally wouldnt suggest axial motors, but they are supposedly low rpm, high torque.


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## Bugzuki (Jan 15, 2008)

OK I guess we need some clarification here. I thought when we were talking about inrunner and outrunner it was in reference to if the rotor was on the inside or outside of the stator. I guess I said inboard and outboard on the list. I should change that.

Can some one also explain what the are refering to with axial and radial? Again I thought this was refering to the rotor location internal or external.
Thanks

Edit - You can buy anything off the shelf - the point is to design something people can build themselves and bring the cost down. I still think that an AC motor would be the least costly to build. And a motor with the rotor inside the stator would be the less complicated then having the outter housing of the wheel motor spinning.

Making the motor smaller to fit in smaller wheels would require a new stator design with less coils. This would probably require changes to the control program also. It would be better to just put 15" wheels on the car. I think most cars can fit 15's. Maybe not an Austin Mini.


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## manic_monkey (Jun 24, 2008)

Bugzuki said:


> OK I guess we need some clarification here. I thought when we were talking about inrunner and outrunner it was in reference to if the rotor was on the inside or outside of the stator. I guess I said inboard and outboard on the list. I should change that.


My bad i think, i misread inboard and outboard. yes, inrunner is magnets (BLDC) or squirrel cage (AC) inside and rotating. outrunner would have the stator in the centre, and the outside moving. 



Bugzuki said:


> Can some one also explain what the are refering to with axial and radial? Again I thought this was refering to the rotor location internal or external.
> Thanks


radial motors are the common motors most people know. axial are like this http://www.axcomotors.com/axial-flux_technology.html
both have benefits, both have flaws. 



Bugzuki said:


> Edit - You can buy anything off the shelf - the point is to design something people can build themselves and bring the cost down. I still think that an AC motor would be the least costly to build. And a motor with the rotor inside the stator would be the less complicated then having the outter housing of the wheel motor spinning.


totally agree with you. AC all the way, neodymium is gonna push the cost skyward - probably talking hundreds of dollars for magents alone



Bugzuki said:


> Making the motor smaller to fit in smaller wheels would require a new stator design with less coils. This would probably require changes to the control program also. It would be better to just put 15" wheels on the car. I think most cars can fit 15's. Maybe not an Austin Mini.


may i suggest that the outside measurment of the motor be 9 inches. that way the motor can be inside most wheels from 13" up, or used slightly inbound and connected by a shaft.


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## judebert (Apr 16, 2008)

Bugzuki said:


> Okay, Lets try it this way.
> 
> What size wheel should the motor fit in?
> (just quote and put your name in where you vote)
> ...


My Honda originally came with 13" wheels. It would be nice if the motor could fit there, but 15" is more realistic, I think.


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## judebert (Apr 16, 2008)

Bugzuki said:


> What motor setup do you want?
> 
> Brushless DC - Inrunner
> 1.
> ...


An AC outrunner, like a hub motor, would work for me too. But I'm also willing to attach an AC inrunner to a diff or something.


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## Bugzuki (Jan 15, 2008)

judebert said:


> An AC outrunner, like a hub motor, would work for me too. But I'm also willing to attach an AC inrunner to a diff or something.


An AC inrunner could also work very nicely as a hub motor. Here is a very high tech Paint CAD drawing , but I think it shows the idea.


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## 3dplane (Feb 27, 2008)

At manic_monkey!
You say you never seen an AC outrunner before.Have you ever seen a ceiling fan? Watch out they are torquey..
About neo prices http://www.magnet4less.com/product_info.php?cPath=71&products_id=48 (Please don't shoot me if the link is screwed up first time linking) Anyways over ten 1.5" X 3/4" X 1/4" $1.79 each.That would be a ballpark size. I really want to get a hold of two F&P motors and see how much power could be pushed out of them in different configurations.(winding and magnets).Currently for a few hundred bux I could get a 5KW brushless sensorless controller (castle creations phoenix HV 110) but It's too big for my planes and too small for an EV. However it could be used for testing the motor I havn't built yet..
I too agree the controller has to come first I just have no clue what you guys are talking about(technical).I did cry my eyes out laughing when Judebert accidentally called bugzuki...BUGZILLA (a few posts earlier)
Barna


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## judebert (Apr 16, 2008)

3dplane said:


> I did cry my eyes out laughing when Judebert accidentally called bugzuki...BUGZILLA (a few posts earlier)
> Barna


Aw, c'mon, it's an easy mistake! Have you seen that car he has for an avatar?


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## ga2500ev (Apr 20, 2008)

Hi guys,

I've read this entire thread and you've really peaked my curiosity. I hope you won't mind if I ask a side question here.

Would it be possible to build a BLDC motor that can be used where a traditional ADC or NetGain motor is placed for an EV?

While reading this thread I did my research on BLDC motors. No brushes and a fixed stator seems to bring the possibility of a DIY motor into focus. An outrunner with a squirrel cage mounted to an end plate on a bearing seems feasible. It also seems to me that the power of such a motor can be improved by stacking modules that extend the length. So if you use the magnets suggested by 3dplane then each module would be about 1.5 inches long.

I'll be the first to admit that I know virtually nothing about motor design after the basics. I'd be eager to find a resource that can explain how one configures for a particular RMP or torque profile.

But it seems like with magnets being cost effective, and the physical configuration at least possible in a BLDC, fixed stator configuration, that it would be at least worth examining.

Also doesn't regenerative braking come back into play too in this configuration? Since there's a permanent magnet rotor, no field needs to be generated to produce power.

I'll understand if the idea needs to be shot down. But I just wanted to know if it were possible.

Thanks,

ga2500ev


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## ga2500ev (Apr 20, 2008)

Microchip has an application note that discusses the design of BLDC motors and its control (using Microchip PIC parts of course). You can find a copy here:

http://oretano.iele-ab.uclm.es/~mhidalgo/temas/Brushless/00885a_fundamentos_BLDC.pdf

ga2500ev


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## OHM (Jun 30, 2008)

Arent magnets very sensitive to vibration or knocks? If so AC will make a better hub motor.

Also In general there isnt even an affordable AC motor so hub or pancake style so it wouldnt really matter as long as we have an efficient and affordable AC solution.

Wheel size should be no bigger than 15 inch as this will suit all types of cars.

Even the standard drag and racing tyres dont get bigger than that.


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## manic_monkey (Jun 24, 2008)

OHM said:


> Arent magnets very sensitive to vibration or knocks? If so AC will make a better hub motor.
> 
> Also In general there isnt even an affordable AC motor so hub or pancake style so it wouldnt really matter as long as we have an efficient and affordable AC solution.
> 
> ...


neodymium magnets are also ruined by heat (150c i think destroys them)


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## Bugzuki (Jan 15, 2008)

So it looks like we should make an AC induction Motor - designed to fit in a 15" wheel. Agreed?

Next -- Inrunner or Outrunner? Can you all come up with some sketches of motor layouts you are picturing - for more ideas.

Knowing that we want to start with AC induction we can start on the motor design. We need to determine the number of coils in the stator, what size wire we need, how many cross bars in the rotor, (probably will differ if we do an outrunner or inrunner design). Most of all we need to keep moving forward (watch "Meet the Robinsons" last night).

Then after that we can look into other configurations if desired. As GA2500EV asked. I hope to have a design of motor and controllers that can be changed around to suit you exact situation. Once the developement is done and understood fully it would be much easier to reconfigure it to another application.

I called the car in my Avatar "Bugzuki" so I have just always used that name on forums. I put a VW Bug body on a Suzuki Samurai Chassis. But, that is off topic. Thanks for the interest though.


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## Bugzuki (Jan 15, 2008)

Another thing to think about. Do we want a water cooled or air cooled motor? With a hub motor it might be efficient to have air cooled, but might be hard to air cool the stator if we go with an outrunner design.


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## manic_monkey (Jun 24, 2008)

15 inch wheel, ac induction motor - totally agreed

in the case of inrunner vs outrunner, which would be easier to seal for protection from the elements? is that even going to be a factor?

has anyone given anymore thought to the axial vs radial pro's / con's or are we just going to go radial?


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## LoganRun (Jun 28, 2008)

AC motor sounds like a great way to go. However, AC controllers are a lot more complicated. Making them DIY will be very challenging.


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## manic_monkey (Jun 24, 2008)

just did a bit of quick maths. 15 inch wheels with a 60 sidewall gives about 193cm diameter. so 80mph is about 1000rpm. 

((80 * 1609) / 60 = 2145 meters per minute then 2145 / 1.93 = 1111 rpm)

thats a lot of torque at low rpm. in fact, in a 4 pole motor, the controller would be running around 36.6hz

would more poles = more torque?


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## Bugzuki (Jan 15, 2008)

LoganRun said:


> AC motor sounds like a great way to go. However, AC controllers are a lot more complicated. Making them DIY will be very challenging.


Actually from the research I have done so far - the controllers are the same it is just the control algorythme that is more complecated for the AC over BLDC.



manic_monkey said:


> just did a bit of quick maths. 15 inch wheels with a 60 sidewall gives about 193cm diameter. so 80mph is about 1000rpm.
> 
> ((80 * 1609) / 60 = 2145 meters per minute then 2145 / 1.93 = 1111 rpm)
> 
> ...


I know that with more poles you have to have a higher frequency to get the same RPM, but I do not really understand the formula to calculate torque. I will have to look at it a gain. 

If we could get an off the shelf planetary gear set to go in it we could get a little more torque out of the motor. But, it would be impossible to have a DIY planetary, so if one is not available then that is out.


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## LoganRun (Jun 28, 2008)

Bugzuki said:


> Actually from the research I have done so far - the controllers are the same it is just the control algorythme that is more complecated for the AC over BLDC.
> 
> 
> AC controllers are definitely more complicated than DC. That is the reason they are more expensive and hard to find.  The controllers have to be matched with the motor or they won't work. Whereas a DC controller can be used with virtually any DC motor. I thought there was a schematic of an AC controller on this forum somewhere. If anyone knows where it is, could you link it in?


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## manic_monkey (Jun 24, 2008)

Bugzuki said:


> Actually from the research I have done so far - the controllers are the same it is just the control algorythme that is more complecated for the AC over BLDC.
> 
> 
> 
> ...


I went looking once for a formula to calculate torque, and got told to stick weight on the end of a foot long stick connected to the motor 

The way i envisage the torque of a motor would be related to the magnetic surface area and its distance from its rotational axis. so, in the case of an inrunner, the larger the diameter of the rotor, the further its outside edge is from its axis, therefore the magnetic field would have more mechanical advantage (like having a longer lever). and of course, the longer the rotor, the greater the magnetic field acting upon that lever. 

Problem is that with a hub motor, the total outside diameter of the motor is going to limited to about 9 inches, and maybe about 6 inches deep. If im right, an outrunner would give the greatest torque / size ratio for a radial motor


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## manic_monkey (Jun 24, 2008)

a little something i just found that confirms what we thought, and gives a little insight into motor heating


*Torque*

The more poles, the more torque at the expense of rpm. So a motor that is designed for 60hz is huge for it's torque. A typical 30hp 60hz motor is 18" around by 20" long and weights 100's of pounds. But it can be made with unsophisticated materials because 60hz is such a low frequency, that the reactive losses are low. Now take the traditional 4 pole motor and turn it into a 12 pole motor, same amount of windings and iron and the torque triples, but 600rpm and you can't drive very fast. The solution is simple, crank the frequency up and gear down the result. Now a 100lb 10" diameter motor 10" long can do the deed. The issue becomes the added heat generated as the ac field in the laminations changes polarity more times per second, the cheap laminations don't like changing magnetic polarity and resist giving off heat. The currents are stronger and the cheap oxidation layer between the laminations is insuffient to stop eddy currents from spiraling between laminations forming even more loss. The windings vibrate more and self destruct in less time.


Because were most likely going to be using 'cheap unsophisticated materials' its probably going to be worth using a low a frequncy as possible. an 8 pole motor would double our torque, and require ~75hz @1100rpm. 12 poles would tripple it, but require ~110hz @1100rpm. might be better to stick to the 8 pole motor and the lower frequncy, especially since were probably not going to have room to fit a fan


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## aeroscott (Jan 5, 2008)

LoganRun said:


> Bugzuki said:
> 
> 
> > Actually from the research I have done so far - the controllers are the same it is just the control algorythme that is more complecated for the AC over BLDC.
> ...


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## OHM (Jun 30, 2008)

the more I look at it the less Im worried about a hub motor.

A cheap AC motor and controller would be ample for starters.

Like Master Po said ¨grasshoper must learn to walk before leaping¨


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## Darrell (Jul 7, 2008)

I've been thinking about this for a while. Just about every rotating part on a car could be used as a rotor in a motor. For example a truck drive shaft could be fitted magnets and be used as a rotor for an electric motor. Instant hybrid! Drive shafts and easily accessible and it's the perfect location for added weight. 

Why are we making a big deal out of this? Somebody could be 

My 2000 Metro has a unique feature on one of the drive shafts. Part of the drive shaft is stationary and doesn't pivot. It's like a shaft extension just waiting to be used for a hybrid. I was thinking of connecting to it with a thick 4 inch belt and a motor, but of how exactly to connect it. 

It seems to me to best way make a hybrid would be to use the existing shaft as the motor rotor. 

What do you guys think?


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## dbc105 (Apr 30, 2008)

I would like to build a hub motor for a motorcycle. this would leave all the extra room for batteries. the only thing I have found are the small ones for bicycles & scooters. I have some ideas but I don't know what is required to reach a certain amount of torque. as for the weight issue, I don't believe the extra weight will be too much of a problem. think about a Chevy with a full rear axle. a couple of hundred pounds and they ride good. look at these guys now days with 24" wheels. as crazy as it looks they don't seem to have too much trouble driving due to unsprung weight. also think about the rear tires on some of these custom motorcycles, they look 2 foot wide, also I have ridden a bike with a hard tail and it did not ride bad at all. just the biggest bumps. I understand trying to keep it at a minimum but unless you are building a race car I don't see any problems. some of the designs I have seen the designs that the RC motor builders are using look pretty good and easily scalable. 

Thoughts anyone?

David


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## manic_monkey (Jun 24, 2008)

Darrell said:


> I've been thinking about this for a while. Just about every rotating part on a car could be used as a rotor in a motor. For example a truck drive shaft could be fitted magnets and be used as a rotor for an electric motor. Instant hybrid! Drive shafts and easily accessible and it's the perfect location for added weight.


the material of the driveshaft likely not suitable for electric motors. its magnetic qualities have to be right for the motor to achieve decent efficiency. 

even if we assume it is made of the right stuff, you still have to fit magnets to it, build and fit field coils around it, put a bearing at either end of the shaft to ensure it runs true with the correct rotor to field gap at all points. it would be less work to just fit a off the shelf motor



Darrell said:


> My 2000 Metro has a unique feature on one of the drive shafts. Part of the drive shaft is stationary and doesn't pivot. It's like a shaft extension just waiting to be used for a hybrid. I was thinking of connecting to it with a thick 4 inch belt and a motor, but of how exactly to connect it.


If its a front wheel drive car, it has a seperate shaft for each side, seperated by a differential. you cant power just 1 side. 



Darrell said:


> It seems to me to best way make a hybrid would be to use the existing shaft as the motor rotor.
> 
> What do you guys think?


i think your wrong


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## manic_monkey (Jun 24, 2008)

dbc105 said:


> I would like to build a hub motor for a motorcycle. this would leave all the extra room for batteries. the only thing I have found are the small ones for bicycles & scooters. I have some ideas but I don't know what is required to reach a certain amount of torque. as for the weight issue, I don't believe the extra weight will be too much of a problem. think about a Chevy with a full rear axle. a couple of hundred pounds and they ride good. look at these guys now days with 24" wheels. as crazy as it looks they don't seem to have too much trouble driving due to unsprung weight. also think about the rear tires on some of these custom motorcycles, they look 2 foot wide, also I have ridden a bike with a hard tail and it did not ride bad at all. just the biggest bumps. I understand trying to keep it at a minimum but unless you are building a race car I don't see any problems. some of the designs I have seen the designs that the RC motor builders are using look pretty good and easily scalable.
> 
> Thoughts anyone?
> 
> David


a hub motor for a motorcycle would actually be quite simple to do. 

1. find a rear tyre with a drum brake. open it up and you'll find a hub cavity thats perfect to line with nice neodymium magnets. take out the shoes and all of the gubbins. leave in the drum liner, cause it will be cast iron and provides a perfect magentic material to enhance your magnets.

2. go around looking for the biggest engine motorcycle you can and pull out its stator. you'll need to find one thats as big as possible to fit inside the hub. you want the gap between the stator and the magnets to be as small as possible. probably best to buy your magnets after youve got a stator as then you can select the best possible thickness. the stator will have to have a certian number of poles. i think it needs an odd number, but i really cant remember so dont quote me on that. if you have a wide rear tyre, you may need more than one of the stators and will have to put them together to form a super-stator. youre gonna be rewiring it anyway, so it shouldnt be too much of an issue.

3. the wheel and hub will rotate around the stator, so the stator has to be fixed to something solid. luckily, the drum brake cover that normally covers the hub cavity is a good candidate. attach stator to drum brake cover, reassemble. the drum brake cover normally attaches to the swing arm. this will probably need beefing up a bit.


this is clearly an over simplified how-to, but you should be able to see that there is plenty of possible to make a hub motor quite easily out of readily available parts. the real issue is wether you can make a hub motor that is powerfull enough to be of any use in a motorcylce.


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## dbc105 (Apr 30, 2008)

Yes it does sound simple enough but not knowing details is one of the problems. such as if I build a BLDC motor, what amount of power can I get out of a given diameter stator? what gauge wire do I need to use? how many turns of wire around each stator pole? how to best match the magnets for the power I need? these are just a few questions I have. looking at bikes to use, I am thinking something along the lines of a Kawasaki EX500(Ninja). these bikes are a good mid size bike and have a full fairing so when done the only change noticed would be the lack of pipes and the streamlining will help some. as for a motor hub, a large one like the front brake hub of a early '70s Suzuki GT750 could easily be re-laced to a different rim if needed. Or would I need to have one casted to be large enough to create the needed power. when making the stator how thick should each lamination be? how many laminations? would a stator out of a ceiling fan work if the sizing was right? 

a lot of questions, where do I find the answers?

Thanks,
David


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## Bugzuki (Jan 15, 2008)

The stator laminations are really thin. I had my Ranger AC induction motor open this weekend, but I did not try to measure the laminates. But I would guess something like 1/32nd of an inch or maybe a Millimeter. 

There were 48 Stator poles and 36 rotor bars. I do not know if this equates to a ratio of 3 to 4 for a 4 pole motor. Does it matter how many bars are in the rotor? Does anyone know or could anyone verify?

I was looking through bearings and came across hubs with integral bearings. These units are available in many different bolt patterns, so I am sure we could use them for almost any vehicle - depending on the wheel alignment hub diameter.

Here is picture to illustrate my thoughts.










You can even get them from Amazon.com
http://www.amazon.com/Precision-Automotive-Industries-513084-Assembly/dp/B000YE58XQ (picture link did not work)

What I was thinking is with one of these hub bearings we could have the motor housing bolted to the inside flange area and then we only need the one bearing and we already know that it is designed for the harsh conditions seen due to vibrations and the loads due to turning.

The rotor would just have a shaft with some splines that would need to match with ever hub the individual selects. The shaft would then be inserted into the hub. This way everything would be centered automatically, and there would be less opportunity for assembly error.

I started a generic motor design. But, it uses two bearings (I had not found the Hub bearing combo yet), so I might have to reconfigure the design to accommidate the hub bearing.

What do you guys think?
Paul


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## Bugzuki (Jan 15, 2008)

Of course there would need to be a nut on the outside of the hub to hold the motor shaft in place. That of course would mean that the rotor was locked in place also.

Here is a page with a lot of examples and some diagrams.
http://www.ebi-bearings.com/pro-wheel-hub-units-3rd.htm


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## smahnken (Jul 23, 2008)

New forum cruiser here. I just finished reading through (most) of the thread, and have a couple comments --

On the BLDC vs. ACIM dilemma:

There's a few pros/cons about the situation that aren't mentioned in post #129. Here's a few things to add to the list.

BLDC motors require active sensing of the stator-to-rotor rotation. This requires that the motor itself contain hall-effect sensors, increasing the complexity of the motor slightly and adding an additional point of failure. ACIM's avoid the problem altogether by inducing the proper magnetic field (hence the name), rather than having to measure the field established by a fixed series of magnets.

ACIM is the right choice for simplicity of motor design, though working with AC does make the controller _drive_ circuitry somewhat more difficult. However, ACIM has some other caveats that may make it unpaletable in this instance. First and foremost, ACIM has a MUCH lower stall torque. Consider the design being attempted -- A hub motor is essentially a transmissionless design. Yes, you can put a planetary gearing system on it, but that defeats simplicity, expense, and really puts a damper on the whole unsprung weight issue. In order to do a direct drive sans-transmission, you'll have to have a more constant torque curve near stall, and that means BLDC.

Secondly, an ACIM inherently requires mass (ie steel) in which the opposing magnetic field can be induced. This results in a larger, heavier motor to get the same amount of torque. If size and weight are considerations, BLDC will do the job more easily.

Lastly, startup currents for ACIM are much higher than BLDC. The power system will need to handle severe current load spikes (starting current can be 5x or more the operating current).

With respect to controller complexity, regenerative braking is supposedly easier with ACIM. I haven't actually reviewed a controller design, so I'm not certain why that is, though I would surmise that it has something to do with the fact that current is inherently travelling both directions anyway. It could also have something to do with the fact that the stator field slips with respect to the rotor field.

-----

On the subject of a boost converter to get you from 144 V to 300+ V: 
This is, on paper, easy to do. But the practicality surrounding the amount of amperage involved will make things quite painful. 

The basic conversion law is that power -- Voltage times current -- remains constant (I'm ignoring the conversion efficiency on purpose). Thus, to get 100 amps (pulled the number out of the air; didn't do the actual 40 kW conversion calc) at 300+ volts, you'd have to provide just over 200 amps at 144V. 

Best to figure out how to get 300+ V worth of batteries to fit and run things natively. Perhaps smaller cells?

-----

In the way of introductions, I'm a EE with about a decade of hardware design experience, including embedded design, CAN bus, and power supply design. I haven't done anything this high power before, but I may be able to contribute some to the cause.

Oh -- and I'm fantastically over-booked, so I may not have much attention span to donate.


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## Bugzuki (Jan 15, 2008)

Welcome to the forum Smahnken.

I think the first thing that needs to be done on the Controller end of this project is to get a free C programmer/compiler application working with the Microchip dsPIC30F6010A microprocessor. This would allow everyone to be able to modify the program to fit their needs. 

Looks like we are going to try to use some of the work that was published in the following article as the base of the unit.
http://www.circuitcellar.com/microchip2007/winners/MT2291.html

But, if the design decides to change to BLDC the above system should still be able to handle it with a few modifications.

So, if you can squeeze in some time somewhere we would be glad to have the help.
Paul


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## 1clue (Jul 21, 2008)

3dplane,

I have been interested in 3-phase for a long time now, and have some book knowledge but no expertise. Most of what I know has been researched based on your posts on this thread or what little I remember of physics from college. In particular, http://www.southernsoaringclub.org.za/ has that 5-part article on brushless DC motors that I found fascinating and simple to understand.

Would you recommend building a small brushless motor from a CDROM before tackling an automotive sized motor? What about you other guys? Would the speed controller and software work just as well on the smaller motors? I think the software would, I don't really care about getting the model motor up to speed, only finding out if the controller works.

I'm a Linux guy and have been for years, so I know about GPL and most of the other licenses. Not much of a Richard Stallman fan, but I can live with it. We might want our participants to go read the license though before we commit to it.

I'd like to participate in this project you guys are talking about, but I'm a long ways from an expert.


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## 1clue (Jul 21, 2008)

JusSumguy said:


> WOW.... I like this.
> 
> 
> 
> ...



This is blatantly false. Switch over to copyright law and check out how IBM introduced copyrighted BSD code into the Linux kernel, and which prompted a lawsuit by SCO.

You guys need to get organized and everybody who works on this project needs to understand what Open Source means. You don't just say it's OS and ignore it. You don't copy commercial designs without permission and possible licensing from the proprietary owner. Google on "Open Source HOWTO" and start reading. There are already open hardware projects that can be modeled from, but you will probably want to apply your own conditions.

You have several projects going on in this thread. You can't call it all one piece unless you're building exactly one type of car, and then your participation and usefulness crumbles. You have software, you have a speed controller, you have a motor. In all realistic situations, you should avoid the one-size-fits-all paradigm because it doesn't work, especially for a bunch of guys trying to whittle an electric car out of whatever they have handy.

If you want an OS project, you need a corporation. An LLC will work fine. For a web site, you can use SourceForge, which is designed to work with open source software.

First you need a charter. Choose something that can encompass all of what you might be, but not so flexible it collapses into a heap of spaghetti. For example, don't choose wheel motors as part of your charter, choose an open design framework for electric vehicles for certain types of use.

Next, you have categories of service:


Motors
AC Induction
PMAC
DC
etc.

Speed Controllers (one for each above?)
Software
Common interfaces for all controllers
Separate modules for each type of thing controlled.

Chargers
Battery management
Etc.

Next, you need to realize that each of these things might want a different type of license. Things regarding hardware design need different protections than pure software, for example. Software is copyrighted, hardware is patented. Not sure what a circuit diagram is, since it's paper which is intended to become hardware. Somebody needs to look at that.

I would start by making a WIKI entry on this site, and only define those things you have decided already and broad categories outside of that. For example, nobody has started a charger project so put in an empty link. Somebody needs to take charge of that and collect a team of central figures to start working on the whole thing.

Once you have the web site and the charter, people will start collecting to fill in the blanks. Each group needs to know how to talk to the others and relay requirements.

Commercial use: You can say "no commercial use" and it may or may not work. Likely what will happen is everyone will look at your design, somebody will realize the circuit is identical to something they already sell and sue you.

What usually happens on OS projects is that the project defines interfaces for individual pieces, and then you have a few people who make implementations of that interface. For example, you have the software project. That will be a core which glues everything together, and a subset of motor-specific modules such as PMAC and DC and such. You will then have a section for different battery types, different battery management systems, etc that can all plug into the main core. Then you'll have different display approaches so everyone can create useful screens of their own instead of just keeping the default one.

If some commercial enterprise wants to use the project, the LLC can then decide to sell it under a different license and pay the contributors, or sell parts of it whose contributors are amenable to that.

Sorry if this ruffles feathers. I think it's a great idea, but it needs to be done right.


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## 1clue (Jul 21, 2008)

I hate to beat a dead horse here, but I feel I need to explain my previous post somewhat.

You, as an individual, can copy any patent and build one of whatever it is for your personal use. That is true.

However, an Open Source project is not "personal use." OS is copyrighted material, copyrighted by the authors in such a way as to ensure that this material stays free for anyone who wants to use it within the constraints of the license. You are saying, "This design is MINE and here are the conditions in which you can use it." Taking some other patented or copyrighted material and releasing it under your own license without permission is identical to any corporate espionage or infringement.

For the user, what this means is that the people who designed this thing did so without stealing any secrets: The OS project is guaranteeing that they need not worry about patents or copyrights from someone else. It means that even though the project might have reverse engineered somebody else's product, they made their own implementation of it which did not copy privately held work.

It also means that the thing is *not* in the public domain. Public domain is like the design for the wheel. It's been around forever, and anyone can do anything they want but nobody can copyright or patent it because prior art exists back to the cave man days.

Thank you for your time.


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## 1clue (Jul 21, 2008)

There is a wealth of motor design info on the following forum, the only thing is most of it is related to model airplanes. The thread I linked to is talking about making large stator plates for a direct drive electric vehicle, which pertains to this discussion.

http://www.rcgroups.com/forums/showthread.php?t=903079

As I said, it's a modeler's forum. However, there is a lot of linked information and you can search the tree of sites to get just about anywhere. Most interestingly, there are people on that forum who have already built their own designs and already cut plates for their own projects.

I've found a local place that can make custom high-quality plates as long as they are no more than 8" wide. According to one of the resources on the rcgroups forum, it's common practice to make a stator segment (say, divide the stator plate into 6 or more parts) and then stack them like you would a brick wall, so each layer is staggered.

I seriously did not mean to put a damper on this discussion. I apologize for any ruffled feathers. I'm not saying you can't do what you intend, only that some of the assumptions made earlier in the thread have been false.


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## manic_monkey (Jun 24, 2008)

1clue said:


> There is a wealth of motor design info on the following forum, the only thing is most of it is related to model airplanes. The thread I linked to is talking about making large stator plates for a direct drive electric vehicle, which pertains to this discussion.
> 
> http://www.rcgroups.com/forums/showthread.php?t=903079
> 
> ...


hey no worries mate, no offence taken. cheers for the link on how people are making stator laminations - i must admit this area is certainly a concern for me, especially since im wanting to do this as cost effective as possible.

btw, i dont think youve put a damper on the discussion, its just going through a bit of a lul at the moment. it'll pick up soon


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## 1clue (Jul 21, 2008)

manic_monkey said:


> hey no worries mate, no offence taken. cheers for the link on how people are making stator laminations - i must admit this area is certainly a concern for me, especially since im wanting to do this as cost effective as possible.
> 
> btw, i dont think youve put a damper on the discussion, its just going through a bit of a lul at the moment. it'll pick up soon



Manic,

Thanks for your response! It's always a bit unnerving when I make a post to a list and all discussion stops for days.

My concern regarding OS is that you intend for the things you do to be free for everyone within your terms, and there are actual requirements for that to come about. I'll help in whatever way I can.


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## OHM (Jun 30, 2008)

Bugzuki said:


> Welcome to the forum Smahnken.
> 
> I think the first thing that needs to be done on the Controller end of this project is to get a free C programmer/compiler application working with the Microchip dsPIC30F6010A microprocessor. This would allow everyone to be able to modify the program to fit their needs.
> 
> ...


I was wrong the main problem with AC conversions is the Controller!!!
They are so expensive!!!
So I change my opinion and think the AC controller is more important
one that could run an existing low rpm 4 pole motor commonly available
and light enough to be used in many conversions eg 11-15kW aluminium caged 4-pole High Output Motor. 
Then it could be run with an off the shelf planetary box like the Azure dynamics one and wed have a strong industrial motor easily available
throughout the world.

So really the controller is the missing link. Hub motors are too impractical and complicated to implement.

For FWD youd need a planetary box like azure dynamic´s setup for rwd the differential could be use as direct drive by changing the crown and pinion to suit etc.


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## Bugzuki (Jan 15, 2008)

hey, nice to see some posting. I have been busy the last couple weeks and did not get on here. 

*1Clue* - it was not you that made the thread pause. If you notice there was a week between my last post and your first.

I think it is great to have someone that can help figure out the OS rules and what we need to do. I vote 1Clue head of that department.

MadMac is moving along with the controller. He is also working on getting a charger integrated into the controller. 

I have been working on the hub motor design, but need to revise it since I found the integrated hub/bearing/speed sensor. I hope to work on this some this weekend. Batman tonight though.

I was thinking with the hub/bearing that could probably work as a plateform for attaching a flywheel to and attaching to the tranny. I am going to contact Timken and see if they have the capability to make specific units for us.

*Full Horse* - We are not at the point of having any idea how much this would cost. I can not see it costing less then 1000 dollars for all of the parts - I think that is on the low side. 

*OHM* - thanks for coming over to the dark side.

maybe once I get some more work done on the Motor I will post some pictures for your review.


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## wilcorp70 (Jul 9, 2008)

Honestly, if you think that wheel motors are beyond the scope of diy, I would disagree. Wheel motors were designed and raced with by Ferdinand Porsche in 1897. There are tons of things that are too complicated to be built and yet people do it all the time (just search for diy cnc milling machines sometime). There are enough naysayers telling us we can't; thats not the purpose of this forum.
But getting back to stator construction, there are a few things to consider. Building in sections affects the motor, in certain applications this is ok, in some its not. There is an article from a technical journal about it on the website below, a very good read if you are considering this construction method. Other methods include, having them professionally die cut (almost certainly prohibitively expensive), cutting them out on your own isn't the best but certainly not the worst idea (see earlier mention of DIY cnc milling machines), or find an acceptably sized motor and use it's stator (modifying as necessary). 
I've posted some articles on my webpage here: LINK. PLEASE click on these! There are a lot of images and technical articles I've collected in my research for building a hub motor. Most of them are BLDC though, but a lot of the principles are applicable. 
Some tools to help everyone: 
-Motor design software (free 60 day trial): 
-This guy is building his own hybrid vehicle (I wish him luck) (He developed a lot motor design tools available on his site)
-There are a couple of open source controller forums out there. The OSMC site has tons of designs out there, and there is a growing collection of schematics, some are for 3 phase motors.
-Another open source motor controller project for EV's. They are using the same controller we are as their starting point.
Lets get started posting some designs up here figuring out how their specs match up and then discuss how to construct them cheap. Even one design would be nice to see in the forum. As for open source, honestly, who cares if it's really open source. I think we all just want a set of instructions we can follow, who cares then if someone decides to sell it or if it is based off of another design so that they can't. Lets just get something done.


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## manic_monkey (Jun 24, 2008)

wilcorp70 said:


> Honestly, if you think that wheel motors are beyond the scope of diy, I would disagree. Wheel motors were designed and raced with by Ferdinand Porsche in 1897. There are tons of things that are too complicated to be built and yet people do it all the time (just search for diy cnc milling machines sometime). There are enough naysayers telling us we can't; thats not the purpose of this forum.
> But getting back to stator construction, there are a few things to consider. Building in sections affects the motor, in certain applications this is ok, in some its not. There is an article from a technical journal about it on the website below, a very good read if you are considering this construction method. Other methods include, having them professionally die cut (almost certainly prohibitively expensive), cutting them out on your own isn't the best but certainly not the worst idea (see earlier mention of DIY cnc milling machines), or find an acceptably sized motor and use it's stator (modifying as necessary).
> I've posted some articles on my webpage here: LINK. PLEASE click on these! There are a lot of images and technical articles I've collected in my research for building a hub motor. Most of them are BLDC though, but a lot of the principles are applicable.
> Some tools to help everyone:
> ...


good stuff man. thanks for the links!


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## Bugzuki (Jan 15, 2008)

Ok, so here is what I have so far.

I decided to go with the integrated hub bearing (just makes sense and there are a ton of variances available).










Here it is in wireframe so you can kind of see the assembly together.









Here is the exploded veiw to show the parts. In this particular model I just guessed at a number of plates and added 50. All of them are not shown in the exploded veiw since that would make it much more spread out and harder to see.










Finally here is the rotor assembly


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## Bugzuki (Jan 15, 2008)

So as you can see I have not started on the stator yet. I might have to resize some things inorder to fit it in, but that is part of designing something.

I did put some holes in the rotor to help lighten it up, but need to know how much mass needs to be around the cage rods. I was planning on just using some copper rods brazed to a ring - that way nobody has to try and cast aluminum into the rotor.

The front plate of the housing might have to be made out of steel in order to get enough strength. The back housing might also. I might end up putting a bearing on the back side of the rotor shaft just to add a little support once some analysis is done.

I will also design some sort of mounting location for a brake caliper. This will most likely be on the motor front housing and the rotor will go on the hub in the standard configuration. 

The Hubs from Timken have a built in ABS sensor (in our project it can also act as a speed sensor. This feature is a great advantage since we will not have to speed time making speed wheels and sensor mounts.

If anyone has any suggestions please send them my way. Right now the outside diameter of the motor housing is at 13.5 inches. And the motor housing is 4.5 inches thick.

Right now the rotor has 36 bars. but that will probably need to be increased due to the diameter of the rotor. I took that number from my Siemens Ranger motor. The stator has 48 coils in that motor.

There is a lot that goes into the motor, so if I have missed anything please let me know. Lets start discussing the specifics on how this motor should actually be designed. I see there are some on here that have a lot more knowledge then me.

Here is a picture of the rotor plate. I was invisioning that people would get them laser cut. It will probably cost around 250 for materials and cutting (that is just a guess).

I have not figured out cooling yet.


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## 1clue (Jul 21, 2008)

Bugzuki said:


> *1Clue* - it was not you that made the thread pause. If you notice there was a week between my last post and your first.
> 
> I think it is great to have someone that can help figure out the OS rules and what we need to do. I vote 1Clue head of that department.


I'm not sure I'm qualified to "head" this stuff. I can help you by pointing out some OS projects and by helping with organization, but you who are doing the work need to pick something. FWIW when the time comes I will probably not use a wheel motor but rather a motor at the end of a CV joint if I can figure a way. It's possible that the same motor will work fine.

FWIW, Open Source rarely winds up being cheaper than a commercially available product in the long run. The only real difference is that a commercially developed product is driven by marketing, and an OS product is driven by _needs._ You guys need the product, you did not find one and so you are making it yourselves, with hopes to share your knowledge with others of like mind.

Wilcorp70's recent post actually says it quite well. The only way it actually matters is if you truly don't want some company to put your work into their commercial product. This forum proves prior art, so they can't patent the design or copyright the software, but they _can_ do whatever they want with it other than that -- except deny you access to your own work, or deny the rest of the community from building their own.


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## xrotaryguy (Jul 26, 2007)

Interesting to see that this has almost turned into an open source power-train thread. I will be watching more closely from now on.


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## OHM (Jun 30, 2008)

Really moving along BUGZuki!! my only input is that the hub have 5 bolt-up flange to allow extra strength.

Ive been looking at the Prius synergy tranny and wondering if larger and thinner 67hp motor can allow you to provide better cooling into the design as two of them should propel most vehicles. 67hp x 2= 134hp. Also the synergy unit is limited by the inverter and some state that 90hp is possible.


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## Bugzuki (Jan 15, 2008)

Thanks for the votes of confidence. The hub/bearing was created directly from the Timken catalog. I also think that it would be better with more bolts - at least 4. I have not heard back from anyone at the bearing suppliers yet. I was trying to find a better way of specifying the hud then just looking through the huge list.

It would be nice if I could get someones help on figuring how much torque a motor would produce and how wide to make the gap between rotor and stator. 

Should I start a new thread with my pictures in it to try and recapture the lost interest?


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## OHM (Jun 30, 2008)

Bugzuki said:


> Thanks for the votes of confidence. The hub/bearing was created directly from the Timken catalog. I also think that it would be better with more bolts - at least 4. I have not heard back from anyone at the bearing suppliers yet. I was trying to find a better way of specifying the hud then just looking through the huge list.
> 
> It would be nice if I could get someones help on figuring how much torque a motor would produce and how wide to make the gap between rotor and stator.
> 
> Should I start a new thread with my pictures in it to try and recapture the lost interest?


Sorry I cant help with rotor to stator gap but are you thinking of forced fan cooling like ducted tubing (similar to ducted racing brakes?) as low rpm will cause heat issues.


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## Bugzuki (Jan 15, 2008)

I have not gotten very far on my cooling thoughts. The motor has to be sealed or road debry would get into it. I don't think anyone wants to get rocks in their motor. I think some water cooling would be the most effective but would raise the weight. Putting cooling fins on the motor housing would increase the complexity of building the housing 10 fold.


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## judebert (Apr 16, 2008)

Lost interest? We've got 23 pages and loads of good discussion. 

In fact, I recently found a TI document that helps explain the bit of the controller software I was having trouble figuring out. That puts me back into working on the pseudocode, which I'm hoping will let us have truly open-source controller software soon.

I just don't know anything about the actual motor design. I figure I'd start small: a little 120V ACIM for my air conditioning compressor. Once that works, I'd like to replace my ADC 9" with a big ACIM, and get regen and charging working. Then I'd like to build hub motors into a small car; I'd start with the rear wheels, and eventually move to all four wheels.

It's a stepwise plan that can actually get us exactly where we want to go, one bit at a time.


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## OHM (Jun 30, 2008)

judebert said:


> I'd like to replace my ADC 9" with a big ACIM, and get regen and charging working.


which ACIM did you have in mind this is something ive been searching for


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## manic_monkey (Jun 24, 2008)

i wasnt sure where to put this, but since were talking about OS controllers here......

when designing a controller, how much should you 'over rate' your transistors by to make sure its not running at its limits? (for both volts and amps)

so if you wanted a controller for 96v and 150A. would you use 100v transistors say, or much higher? would you go 200A or even higher still? what safety margin is a good rule of thumb?


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## smahnken (Jul 23, 2008)

> what safety margin is a good rule of thumb?


The rule of thumb generally adhered to is to over rate by 25%. However, even that margin is dangerous unless you're absolutely positive of your max load rating to begin with.


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## Madmac (Mar 14, 2008)

> i wasnt sure where to put this, but since were talking about OS controllers here......
> 
> when designing a controller, how much should you 'over rate' your transistors by to make sure its not running at its limits? (for both volts and amps)
> 
> so if you wanted a controller for 96v and 150A. would you use 100v transistors say, or much higher? would you go 200A or even higher still? what safety margin is a good rule of thumb?


It is not the static voltage rating you need to consider it is the dynamic ones. When switching inductive loads at fast speeds the voltages seen can be a lot higher. The rating used will depend on the lifetime you want and the quality of the design.

Madmac


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## book_knight (Aug 20, 2008)

Hello all! First, I am really excited about the prospect this forum was started on and that is designing and building a working in hub motor. Second, I have been following along with the forum for a while now and used it to really get a start on where to look for information.

I have made several mechanical designs of a 13.5" hub case in a Brushless DC - Outrunner motor configuration that is sized based on the bearings used and the size of the hub casing. The CAD program I am using allows me to use variables assigned to dimensions, thus allowing me to dynamically modify the parameters. 








Chassis side iso of the hub motor. This shows the layout of the bolt config that should be matched with a particular car.








Wheel side view with the bolt config that should match the wheel to be used.








Similar view as the one above.








Front plate hidden, exposing a possible stator/magnet configuration. I envision that the hub case and magnet placement would be fixed and several different back plate, stator, and front plate configurations can be built to fit in the same housing. This provides for a very flexible motor that could cater to different power/torque requirements by only changing the stator. It also allows for the same case to be used with multiple chassis/wheel combinations by changing those back and front plates.








Stator has been removed and the internal shaft, bearing, and magnets are shown.








Exploded view.


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## 1clue (Jul 21, 2008)

book knight,

Several questions:

First, are you sure those stator teeth will be strong enough to handle the force on them? They seem a lot longer than I expected. I've been hounding a site for remote controlled airplanes since they build a lot of motors there. It's my opinion that the magnets on this motor will have to be very strong in order to get good performance, which means the forces on those teeth might be phenomenal.

Second, you show 24 teeth and 16 magnet poles. Is there a reason for that? What reduction does that give? Why not use more magnet poles than teeth?

Third, how do you intend to wind that? I'm thinking DLRK, but don't know whether star or delta.

Fourth, the magnets seem to be large. Do you plan on having someone fabricate a large curved magnet, or do you intend to use 2 or 3 smaller magnets all facing the same way for these?

Fifth, has anyone given thought to the thickness of the plates? The thinner the better as far as efficiency goes.

Thanks.


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## book_knight (Aug 20, 2008)

1clue said:


> book knight,
> 
> Several questions:
> 
> ...




I have not done any calculations related to strength of the parts. I have not even gone into much detail related to what materials to use. I agree with your assessment. I envision that the stator arms/teeth will be a bit broader and the hub of the stator to be bigger. But that adds a considerable amount of weight. So to compensate, i will probably cut material out of the center of the stator hub to reduce weight. Similar to what Bugzuki did here.
At this point i have no idea about the teeth/magnet ratio or sizes. I was really only trying to get a rough draft variable based mechanical CAD drawing.
Not sure what the "D" in DLRK is, but if its like the standard LRK found here then yes. I like the Torquemax idea. It seems that this would give good torque with fewer windings, which leads to less resistance which in turn results in the same current for less voltage (and heat generation). No idea on the "delta" vs. "star" configuation
Yes the latter ("intend to use 2 or 3 smaller magnets all facing the same way for these"). I plan to use magnets that are small and rectangular and then build up sections to be the effective appropriate size of the overall magnet.
I was going on the order of millimeter for the stator laminates.
My background is by no means directly related to this electrical stuff so i am kinda learning as i go. Much like many of you here. But i think i'll probably attempt to a smaller 5" diameter model to see if i can at least put this motor together...at that point i'm gonna need a controller and power supply. 

The next step is to get the teeth/magnet ratio correct to prepare to begin the machining process.

Hopefully i answered you questions. Let me know if you have any other questions/comments.


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## 1clue (Jul 21, 2008)

Something I had thought was being done here is calculations of flux levels.

I'm not an electrical engineer and I do not know how to do this, but I do know that it's fairly important:

There is a magnetic field set up by the stator, and a magnetic field set up by the rotor, and an electric field set up by the coils. All these fields need to interact correctly to get the best results. The iron content needs to be adequate to contain the magnetic field properly, and needs to have plates thin enough to reduce eddy currents for the frequencies used such that the losses induced by those currents is adequate. The core (iron) material needs to be chosen for good characteristics for the task as well.

Unfortunately that's about all I know about it, and that might be wrong.


The D in DLRK is "distributed." You use the teeth which are empty to add more windings.

I recommend going to rcgroups.com to join in on the motor building section there. There is a huge amount of expertise and a lot of links to get you started. I pretty much paused my activity on diyelectriccar.com in order to build a few CDROM motors.

I figure first thing is to wind a motor that I know works aside of winding. I'll do a few of those (probably the same stator over and over) and then maybe look at figuring out stator plates, and so on.

Some of those model motors get in the 15 kW range, which starts to be interesting as an EV motor just by itself. In fact, one commercial outrunner motor with that rating has a disclaimer that warranty is void when used to transport humans, so it's already been tried before.


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## JimPowell (Aug 20, 2008)

Hi All,

Just joined and read your comments (all 25 pages)

Excellent information and ideas.

Some comments for consideration:
1. I have some misgivings with the motor being in the wheel with the vibration and exposure to debris.
2. If there si a large diameter motor this could be located higher up with belt or chain drives which would take care of the gearing
3. The cheapest commercially available motor (quoted on this site) is $3200.
4. The estimated cost of a motor devised from this site is about $1000
5. The cost of a complete car and specs from China are:
_Model: CYD4030 
Unit Price : FOB Qingdao $*5350*/unit(Motor:4kw) 
Passenger capacity: 4persons 
Range (full loaded): 120km 
Max. Speed: 45kmh 
Minimum turning radius: 3.5m 
Max. climbing ability (full loaded): 15% 
Max. movement after brake:=7.5 meters from 30 km/hr 
Overall dimensions:2565mm*1280mm*1560mm 
Max. loading weight: 400kgs 
Net weight:765kgs 
Wheel base:1700mm 
min. ground clearance:150mm 
Gear Ratio: 7.75 
Charging Time : 8hours 
Body: steel body 
Seats: standard 
Battery: 6x8V sealed lead acid 
Wheel&Tire:Alloy Wheel 145/70R12 
Windows: Power windows 
Driving: LHD/RHD 
Brake system: Drum 
Equipped: 2headlights, 2 front turn signals,2 taillights(eachcombined1 brake light with 1 
turn signal),CD Player, Curtis Controller, Central locking systems,3 points seatbelts 
Color Available:White,yellow,green,red,blue._
6. Not good, but better than the offerings from ZAP motors of USA
7. The Tata Nano car (India, petrol) costs about $3000
8. If we use axial motors, with the smaller diameter, the motor could be located inboard and low down on the ends of half shafts.
9. What are the efficiencies of AC and BLDC motors in the propulsion mode and regenerative mode?


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## 1clue (Jul 21, 2008)

Jim,

There are advantages and disadvantages to each design approach. I tend to agree with you on whether the motor should be a hub motor or not, but the same motor should be able to be run from a CV joint so I'm not complaining much.

However, I fail to see why you quote cars from other countries. If you're in the US, then none of those vehicles can be bought here, so what does it matter what they cost? I'm not getting on your case about it, I just don't understand the relevance.

FWIW, I doubt that those who are following this thread closely are interested in cost so much as doing it themselves. That's certainly the case with me. I'm not made of money or I probably wouldn't be on this site but probably would be on a waiting list for some commercial offering or having someone else do the conversion. The main reason I'm here though is because I want to _build_ one. Even if it costs more, which I fully expect it to by the time it's all done.


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## book_knight (Aug 20, 2008)

1clue said:


> FWIW, I doubt that those who are following this thread closely are interested in cost so much as doing it themselves. That's certainly the case with me. I'm not made of money or I probably wouldn't be on this site but probably would be on a waiting list for some commercial offering or having someone else do the conversion. The main reason I'm here though is because I want to _build_ one. Even if it costs more, which I fully expect it to by the time it's all done.


I agree. I'm in it for the hobby aspect. I've also always wanted to rebuild a older car with new tech. I guess this is my start.


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## 1clue (Jul 21, 2008)

book_knight said:


> I agree. I'm in it for the hobby aspect. I've also always wanted to rebuild a older car with new tech. I guess this is my start.




Personally, my ultimate goal at this point is to build a car from the ground up for this. I'll probably start with a bicycle conversion (winding my own motor) and hopefully work up to an old car conversion after that. I don't intend to jump in at the deep end, but I do intend to do things the way I want rather than the way that's easy.


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## Bugzuki (Jan 15, 2008)

book_knight said:


> Hello all! First, I am really excited about the prospect this forum was started on and that is designing and building a working in hub motor. Second, I have been following along with the forum for a while now and used it to really get a start on where to look for information.
> 
> I have made several mechanical designs of a 13.5" hub case in a Brushless DC - Outrunner motor configuration that is sized based on the bearings used and the size of the hub casing. The CAD program I am using allows me to use variables assigned to dimensions, thus allowing me to dynamically modify the parameters.
> 
> ...


That is a nice design, but I have a few questions/suggestions:

Looks like you only have 1 bearing. That configuration would need 2 - otherwise there would be a large amount of twisting force on that bearing. The bearing I chose has 2 internal bearings and would require some thought into the wheel selection to center the wheel over the hub.

Then, it appears that you have planned to mount the motor to the existing hub and the wheel to the motor. This would move the wheel out the thickness of the motor. Which, I do not think would be possible. The only way it would work is to have a bracket that replaced the hub. This bracket would have to mount to the suspension members and the back of the motor.

Most CAD systems allow the use of variable dimensions. It appears you are using Solidworks? I have Pro/E.



1clue said:


> Second, you show 24 teeth and 16 magnet poles. Is there a reason for that? What reduction does that give? Why not use more magnet poles than teeth?
> 
> Fifth, has anyone given thought to the thickness of the plates? The thinner the better as far as efficiency goes.


The Siemens AC Induction motor I have has 48 stator coils and 36 rods in the rotor. I think that makes it a 4 pole motor - 4 coils to 1 rod, right?

The stator/rotor plates are somewhere better 1mm or 1/16th of an inch. I think it is probably metric, since it was made by Siemens.



1clue said:


> Something I had thought was being done here is calculations of flux levels.
> 
> I'm not an electrical engineer and I do not know how to do this, but I do know that it's fairly important:


I also think that this is very important. And I would like some help if anyone is willing to help. That is why I have not done alot more on the motor design, I need some design perameters.



1clue said:


> There are advantages and disadvantages to each design approach. I tend to agree with you on whether the motor should be a hub motor or not, but the same motor should be able to be run from a CV joint so I'm not complaining much.
> 
> The main reason I'm here though is because I want to _build_ one. Even if it costs more, which I fully expect it to by the time it's all done.


I am still hoping to get a design made that can be reconfigured to meet almost anyones desired application. Once we understand the formulas it should not be too hard to make changes. And improve on the design.

I agree that the main driver is to build one and hopefully drive down the cost of the manufactured motors. But, in order to do that we would need to come up with an efficient design that looks good.


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## bommy (Jul 25, 2008)

HI
I also jointed this topic and I am very interested in "home made" hub motor to fit my old classic car.
But I found some data about hub motor.
http://chinkoching.trustpass.alibaba.com/viewimg/photo/101300864/7kw_Motor_For_Ev.jpg.html
It seems to be out runner hub motor.

*Features Specifications: 7kw Motor For Ev*


7KW DC hub motor
1- High efficiency above 90%.
2- Fit 13" - 15" wheel hub.
3- Evaluation sample available
a-Based on 280mm dia. 130mm T hub motor size. 
b-Drawing required to make the hub motor fit the vehicle
(support to frame, struts (rear suspension, brake disc.)
4- Price per set included one controller and 2 motor (7KWx2)
5- Net weight : 26kg/pc. 
6- Required tooling for mass production.
7-10KW motor sample available with same size, similar torque,
eff. voltage, but higher current and rpm (900 - 1000)
8- Only available for evaluation sample at 3X price.
9- Quantity for Normal price : 100 pcs.

I also see the 5KW hub motor.
http://www.made-in-china.com/image/4f0j00zMotTEUCquqnM/Car-Hub-Motor.jpg
http://www.made-in-china.com/image/3f2j00ICbtuAzcgpqHM/Electric-Car-Hub-Motor.jpg

*Features Specifications: Electric Car Hub Motor*


Brushless dc electric car hub motor 
1) Rated voltage 48V, 60V, 72V 
2) Rated power:5000w 
3) Rated rotating speed:500-800rpm 
4) Rated efficiency:Greater than and equal to 83% 
5) Rim sizes:12'' car rim (it can be with 10'',1314'' car rim)
6) Brushless dc motor 
7)one side shaft out 
It can be used for the electric car.We can make different motor as client's requiremt.

The FOB(5KW) price is about US700.


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## book_knight (Aug 20, 2008)

Bugzuki said:


> That is a nice design, but I have a few questions/suggestions:
> 
> Looks like you only have 1 bearing. That configuration would need 2 - otherwise there would be a large amount of twisting force on that bearing. The bearing I chose has 2 internal bearings and would require some thought into the wheel selection to center the wheel over the hub.


There are two bearings (hard to see from the angles i have provided), but the there is one in the hub casing and one in the front plate. The orange colored cylinders are the bearings (tapered roller bearings i envision). In this configuration the two bearings are separated by the green external shaft that the stator rides on. 

When put together, the backplate/internal shaft combo (at this point built as one unit) --> bearing --> external shaft --> bearing --> nut (not shown) are used to keep the stator stationary relative to the chassis. The nut is thus fixed and the only rotating parts are the hub, outer ring of the bearings, and the front plate. Do you think this is sufficient?



Bugzuki said:


> Then, it appears that you have planned to mount the motor to the existing hub and the wheel to the motor. This would move the wheel out the thickness of the motor. Which, I do not think would be possible. The only way it would work is to have a bracket that replaced the hub. This bracket would have to mount to the suspension members and the back of the motor.


I know very little about cars and particularly nothing about hub/wheel interaction. But i don't think its impossible to have a original hub --> motor --> wheel configuration. This config seems to be a much easier and faster plug-n-play solution than adding the additional complexity associated with designing a hub replacement. Also, by keeping the original suspension, you maintain the dynamics of the vehicle so long as you can simulate the original handling with the motor control system.

I do see an issue with a wheel ending up outside the wheel well which may or may not end up being a significant amount. I guess it would depend on the width of the motor. Also, i can agree with your statement if we are talking about the strength of the original hub and bolt configuration. As in, the original hub is rated to take the weight of a wheel of X lbs., I can almost guarantee that any motor we build and mount will end up with a total hub+motor weight greater than X lbs.. So a buffed up axel + hub may be in order. What do you guys think?



Bugzuki said:


> Most CAD systems allow the use of variable dimensions. It appears you are using Solidworks? I have Pro/E.


You are correct. However, i am learning Pro/E. I find Solidworks to be a far simpler program to learn and Pro/E to have far more flexibility.


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## wilcorp70 (Jul 9, 2008)

There are a couple of problems with the hub+motor+wheel configuration (none completely insurmountable). The hub is attached to the axle which spins, so the axle would have to be welded or somehow frozen in place, otherwise you are losing torque (This adds rather than reduces complexity). Unsprung mass, I know we all hear it on this forum from all the nay-sayers about how unsprung mass will ruin the handling, destroy the suspension, cause cancer, create deadly mutant squirrels, blah blah blahh... But, it is at least a little relevant, generally you want to keep it as low as possible, at the very very most under 100 lbs per wheel (in the back). An outer rotor motor could keep the mass down and fit around the hub, but its still extra weight that isn't doing anything helpful.

Whoever posted the PM motor design, you might want to consider placing the rotor on the inside using magnets in sequential v shapes, like the Prius motors do, this design uses fewer magnets (expensive) while providing only slightly less torque and doesn't require any shaped magnets as well.

Bugzuki, I've got some industry articles on the design of an induction wheel motor, Its got a lot of information about pole number and gap width; the equations are a bit advanced but the variables are all labeled, I'll post a link when I find it in my files. 

After looking at all the information available I think I am going to start posting some of the better designed wheel motors I've found, and see if I can start modifying their construction to better suit the DIY community rather than starting from scratch. First step is stator lamination construction.


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## book_knight (Aug 20, 2008)

wilcorp70 said:


> There are a couple of problems with the hub+motor+wheel configuration (none completely insurmountable). The hub is attached to the axle which spins, so the axle would have to be welded or somehow frozen in place, otherwise you are losing torque (This adds rather than reduces complexity). Unsprung mass, I know we all hear it on this forum from all the nay-sayers about how unsprung mass will ruin the handling, destroy the suspension, cause cancer, create deadly mutant squirrels, blah blah blahh... But, it is at least a little relevant, generally you want to keep it as low as possible, at the very very most under 100 lbs per wheel (in the back). An outer rotor motor could keep the mass down and fit around the hub, but its still extra weight that isn't doing anything helpful.


I have spoken to a friend of mine discussing this unsprung weight concern. It seems that unsprung weight is minimized for the purpose of handling. If that's the case, then the handling issue can be mitigated by individually driving the wheels at the appropriate speed. This will increase the complexity of the control system, but make for a completely customizable handling scheme. Do you think this idea is accurate?


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## aeroscott (Jan 5, 2008)

wilcorp70 said:


> There are a couple of problems with the hub+motor+wheel configuration (none completely insurmountable). The hub is attached to the axle which spins, so the axle would have to be welded or somehow frozen in place, otherwise you are losing torque (This adds rather than reduces complexity). Unsprung mass, I know we all hear it on this forum from all the nay-sayers about how unsprung mass will ruin the handling, destroy the suspension, cause cancer, create deadly mutant squirrels, blah blah blahh... But, it is at least a little relevant, generally you want to keep it as low as possible, at the very very most under 100 lbs per wheel (in the back). An outer rotor motor could keep the mass down and fit around the hub, but its still extra weight that isn't doing anything helpful.
> 
> Whoever posted the PM motor design, you might want to consider placing the rotor on the inside using magnets in sequential v shapes, like the Prius motors do, this design uses fewer magnets (expensive) while providing only slightly less torque and doesn't require any shaped magnets as well.
> 
> ...


 I'm very nervous about the mutant squirrels . Great find on the motor data . from the magazine "Automotive Engineering " Nissan will use a " Super motor " at each wheel ( two coaxial motors one running the ring gear the other running the sun gear on a planetary gear set giving variable gear ratios and a 98% efficiency ). what ratio do you want and when .


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## Schmism (Aug 16, 2008)

aeroscott said:


> ( two coaxial motors one running the ring gear the other running the sun gear on a planetary gear set giving variable gear ratios and a 98% efficiency ). what ratio do you want and when .


As a mechanical engineer with extensive automotive background, i think this is a key point that has been glossed over so far.

While i understand that the design of the motor is from ground up, i dont think many people have taken time to consider the real world numbers if you want direct drive.

takeing the avg pass car tire of a 205/60R15 puts an outside diam of about 25"

at top speed of 130 mph how fast does the tire turn?
130mph=190feet per sec

how many feet does the tire move in one rotation? (circumference)
pi*D = 3.14*2.08ft (25" in feet) = 6.54'

190/6.54=29 revs per sec *60 = 1748 rpm 

so your motor design maxes out at ~1750 rpm.
*
you guys can really build a motor that generates the required torque from 0-1750 rpm? (thats direct drive no additional gearing)*

Even the seimens/ford 3ph ac motor used an integrated diff (reduction gearing) bolted to the housing of the motor. 

other large equipment uses planetary gearing at the wheels to reduce high input speeds and reduce torque requirements of upstream components. 

there were some early questions of mounting into the suspension, it may be of interest to bring it up again as current suspension design lends itself well to standard size/shape motors.

this is a standard knuckle off the front of a 4wd truck. the shinny sliver cone thing is called a spindle and supports the bearings that are held inside hub (not seen) that transmits the power from the axle shaft in the middle to the rim (ie tire) that is bolted to the outside of the hub. 










its relevant because that huge chunk of metal (called the knuckle) transfers all the weight of the vehicle to the tire. Its a substantial piece. as you can see it would be easy to replace input drive shaft on the back with a drive motor bolted directly to the face of the knuckle. 

hears what an IFS system looks like (similar knuckle design) with upper and lower A-arms. This suspension works well as there is no spring in the way of the inside because it's torsion sprung off a bar either at the top or the bottom (chevy uses bottom, toyota uses top)








*
to use a similar setup with an 8-10" diam motor of 12-18" long would fit inside fairly "normal" IFS setups.*

FYI most front wheel drive cars integrate the above IFS knuckle with a coil over shock and no upper a-arm 



Its my understand that most if not all manufactures tackling an EV still have some sort of reduction gearing involved. If they could design a motor within the physical dimension limitations required, with the appropriate power/torque/rpm range and make it direct drive, i can not think of a reason why they wouldn't.

As they haven't my guess is this (gearing issue) is going to be a significant limitation to a "simple" hub motor design. 

While the purist of the hub-motor might poopoo a central (per 2 wheels) motor design with minimal differential gearing it does seem to solve a number of significant limitations to the hub motor

THe H1 alpha hummer uses inboard disk brakes, IRS with portal hubs (gear reduction at the wheel of nearly 2:1)

-removes unsprung weight
-removes motor from wheel/road vibration 
-removes motor from excessive salt/mud/sand/water/dirt etc
-allows simple differential gearing to compensate for turning radius speed variance (as opposed to complicated motor controller design)


in light of the above issues, if pressing forward with such a hub motor design, keep in mind the simplest suspension design is to likely integrate the suspension links to the outer motor housing thus increasing the case design significantly (likely have to be cast and not simple sheet metal cylinder)


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## OHM (Jun 30, 2008)

I agree with myself having mainly a motor mechanical background.

Reduction gearing is essential to suit lightweight high revving ac motors.
Cooling and durability will be an issue with the elements and vibration.

I still think its best to design a controller to power most off the shelf industrial AC motors. Also even to modify whats out there to rev higher
and to make them lighter.

There is more than one reason why hub motors in motorcars haven´t caught on.

mistubishi quote from Tory Hashimoto


> In the beginning, we produced the Colt EV MIEV with two rear in-wheel motors. Later the same year, in August, we went to a four individual motors drive system for the Lancer Evolution MIEV (Mitsubishi In wheel Electric Vehicle). The following year, in October 2006 we changed again and this time to one single motor driving through a differential to two rear wheels. This is because the “i” MiEV is very compact A segment vehicle. We found people do not want a high performance vehicle, so we changed from using four separate motors to one single motor drive system. This has brought us to a more affordable arrangement. Also, we do not need the additional development time period to develop an in-wheel system. For we want to introduce such an Electric vehicle as soon as possible to the real market.


Its all down to cost, application and the not so advertised durability issues that lead to warranty headaches.


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## Bugzuki (Jan 15, 2008)

Ohm - I am glad you agree with yourself. I just could not resist.

The main issue with unsprung weight is road vibration and bumps, not as much with performance. If all roads were perfectly flat and smooth there would be no need for suspension. But, since we live in an imperfect world there are bumps and stuff. With a high unsprung weight more of that vibration is carried through the supension to the drivers backside. The is no way to mitigate that through motor programming.

Those two suspension pictures are from 4wheel drive trucks. most passenger cars have a very small distance from the knuckle to the Hub. This is done to try and keep the tire/wheel centered over the hub bearings and as close to the drive shaft joint as possible. If the motor is bolted to the existing hub or knuckle that will move the leverage outward making more torque trying to twist the knuckle upward. This would also force the wheel to turn (steering) in an arc instead of rotating about an axis.

My oppinion is that the knuckle would have to be replaced. I am not talking about thin sheet metal I am talking 1/2".

Like I stated way back. I would also much prefer a single central motor. Looks like most of the people that want wheel motors want a BLDC outrunner. So, maybe I will change my design to be a AC Induction central motor. And Book Knight can keep on working on the hub motor design. 

I would be very interested in getting any information I can on motor design specs and formulas. The more I see the better I can understand.

I left gear reduction out of my motor design because that introduces a ton of issues like more complex for a DIYer, introduction of lubrication and more sealing issues. Maybe I will start working on a design that can be mounted to a tranmission. Then we can change the design from there to include gear reduction and a differential to get rid of the added weight of the tranny and all the extra gears. A planetary can natively do two different gear ratios and an AC induction motor can rotate either direction without any issues.

Should I start an new thread called "Open Source 3ph AC induction motor design"? Then as others get closer with a controller design we can have some motor options.


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## OHM (Jun 30, 2008)

oops I forgot the comma! 

Bugs i cant speak for you or others just that there are so many industrial Ac motors going for so cheap and the only thing they need is a good drive.
The drives available like Danfoss vlt 5042 are too big and expensive.
If something like Azure was available say for 2500 then there is no reason to go any other way.

On the other hand how many lightweight AC motors are available without paying a squillion?

Could it could also be possible to design a strong yet lighter cage or casing that takes better bearings but uses the internals of cheaply available industrial motors?


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## Schmism (Aug 16, 2008)

Bugzuki said:


> Those two suspension pictures are from 4wheel drive trucks. most passenger cars have a very small distance from the knuckle to the Hub. This is done to try and keep the tire/wheel centered over the hub bearings and as close to the drive shaft joint as possible. If the motor is bolted to the existing hub or knuckle that will move the leverage outward making more torque trying to twist the knuckle upward. This would also force the wheel to turn (steering) in an arc instead of rotating about an axis.


I naturally assumed we were thinking rear drive wheels only, as rotating a huge rotational mass creates significant gyroscopic forces when trying to turn. (probably on the order of magnitude that makes it infeasible to use on steering wheels)

-another issue with hub-motor if you wanted AWD or FWD


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## book_knight (Aug 20, 2008)

Bugzuki said:


> Ohm - I am glad you agree with yourself. I just could not resist.
> 
> The main issue with unsprung weight is road vibration and bumps, not as much with performance. If all roads were perfectly flat and smooth there would be no need for suspension. But, since we live in an imperfect world there are bumps and stuff. With a high unsprung weight more of that vibration is carried through the supension to the drivers backside. The is no way to mitigate that through motor programming.


Ok that makes sense. I had considered the vibrations being a limiting factor in the design of an hub motor.


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## wilcorp70 (Jul 9, 2008)

Well it seems that a lot of people are talking about jumping ship. Don't. Nothing worth doing is ever easy. That being said, this is easier than a lot of other things fitting that mantra.
I was going to wait to post until after I reorganized the papers on my website so I could link to them directly rather than say they are in the large zip files. But, alas I feel the need to speak and then I will post them in a couple of hours. This is not the place for "A hub motor is too complicated, infeasible, impossaffordoable, etc. If you don't think it can be done, don't help; just remember all the other things that they said couldn't be done (we've at least got a head start that someone's done it)
-#1. Starting out, just because car companies don't do something, or claim it isn't cost effective, doesn't mean squat in my book, ever heard of the Tucker?. Honestly, if you believe what they say, why are you even on an electric car forum; they've been saying that they wouldn't be effective for years now. The car companies don't have anyone's interest but their own in mind, which is fine, they are a business. That being said, it is cheaper for them in the long run to use one motor off of a transmission and simpler because, well, its what they do normally and have done for a very long time. They build transmissions for a living, and this makes one large motor very attractive for simplicity, especially when they feel the consumer probably doesn't even know the difference and could care less if mutant squirrels were running their cars (sorry, couldn't resist a second shot at that one). Unfortunately, the DIYer is stuck with an automotive transmission that is at best inappropriately geared for an ev. Its not very simple for someone to build (not impossible, but harder than just a motor). 
-#2. Where are you planning on driving your ev: the autoban? Where are you going to go 130 mph! Thats ludicrous, Just because a car can do it, doesn't mean it has too. Try a top speed of 90mph and redo your calculations, and I will show you a motor design that can handle it. Our cars can do a lot of things that they'll never do, it doesn't mean we have to copy that here. You'd seriously cut your range in any vehicle (gas or electric) doing that speed anyways unless its bullet shaped.
-#3 Direct drive is very possible and is the way cars will eventually run. I have at least one article from IEEE specifically on directly driving vehicles from a motor and I will post it later today once I sort them all. Like I said rework your math with a sane 90 mph. No, its not easy, but in the long run adding anything more than the most basic gearing can only serve to complicate a design, not simplify it.
-#4. If you still think it needs gearing, design one with gearing. I used to think this thread needed to focus on one type of design, but I think a healthy selection is a good idea. As long as we can give guidance to each other. The controller really can be modified, with not too much trouble. Even changing to a switched reluctance motor would only require a change in the waveform from the PWM from sine to triangular. 
-#5. I believe a motor can and should be attached to the original knuckle of the car, many of the designs I have looked at, design with this intent, and while some careful structural analysis is needed, it isn't too difficult.
--Well, there is my rant, sorry to take up so much space. We are closer than any group has ever been to actually designing and building working wheel motors. It took us long enough to focus and get on track, but now that we are there we can't just bail. I think it is time to split the thread though into controller/motor, and maybe even restart this thread with the designs and links we already have so people don't have to go through the whole thing just to figure out that we've really just started designing things.


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## CNCRouterman (May 5, 2008)

Ok, there have been numerous references to these stator plates. Can someone spec the material, plate thickness and shape, a cad file would be best, but even a pdf or raster image would be good. I want to run the concept past one of my customers who is into sheet metal forming, punching and stamping. Maybe we can get a fair shake if the demand and material specs come together.

I have read that high nickle content is desirable to reduce hysteresis losses, but I don't know what to ask for when specifying the material, or how important this factor is for our application.


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## Schmism (Aug 16, 2008)

wilcorp70 said:


> No, its not easy, but in the long run adding anything more than the most basic gearing can only serve to complicate a design, not simplify it.


i suppose that depends on the direction your looking at the problem. From a mechanical side of things i see a simple differential gear (proven tec) that solves a number of (from my point of view) complicated electronic control issues involved with controlling many (at least 2) independent motors while working together as one harmonious one.

I suppose from the other point of view (more a IEEE or softwere side) anything that is more than a wheel attached to a motor is more mechanically complicated than needed.

From my point of view, there are 2 very distinct approaches to this issue.

1) get something reasonably basic that is easy to build and install and get it in the hands of the users ASAP. 
2) spend a longer time developing a more advanced controller (built for multiple Independent wheel motors possibly delaying the roll out of the product.

IMHO vaporware is great to talk about, but at the end of the day, putting cold hard motors in peoples hands to build with will trump any "awesome controller about to be done any day"

To that end, which boat is this group going to peruse (each has its merits)
1) the mythical end all be all hub motor that no commercial car company has managed to produce (for whatever reason)
2) a (perhaps quicker to market) hybrid system somewhere between the current EV conversion of one motor hooked to a transmission to drive axles and the perfect above mentioned hub motor.


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## book_knight (Aug 20, 2008)

Schmism said:


> From my point of view, there are 2 very distinct approaches to this issue.
> 
> 1) get something reasonably basic that is easy to build and install and get it in the hands of the users ASAP.
> 2) spend a longer time developing a more advanced controller (built for multiple Independent wheel motors possibly delaying the roll out of the product.
> ...


I vote mythical "end all, be all" hub motor...and dragons!!! (sorry, i thought a mutating squirrel was a little far fetched).

But i don't see why both avenues cannot be taken. We can make it a race or something. And see which one actually makes it out of vaporware from DIYer's in this forum. 

Car (read: big) companies tend to do what makes money and these things did not make money in the past. That being said, i don't think they have not been able to tackle this issue, i think they have not found it to be cost effective in the current automotive infrastructure.


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## book_knight (Aug 20, 2008)

Please check the following for mistakes and accuracy (using MATLAB):

speed = 60; % miles per hour
time = 6; % seconds
weight = 3850; % pounds
diameter = 24/12; % feet
driven_wheels = 2;

mph_fps = 1.46666667;
lbf_lbm = 1/32.174 ;

velocity = speed*mph_fps
circumference = diameter*pi
mass = weight*lbf_lbm

RPM = velocity/circumference*60
Energy = 1/2*mass*velocity^2
Power = Energy/time
Torque = Power/(2*pi)*60/RPM
Force = Torque/(diameter/2)

velocity = 88 fps
circumference = 6.2832 ft
mass = 119.66 lbm
RPM = 840.34
Energy = 4.6333e+005
Power = 77222 Watts
Torque = 877.52 ft-lbf
Force = 877.52 lbf

Have not done calculations for max speed of about 100mph (red line). Please suggest additional or modified parameters.


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## wilcorp70 (Jul 9, 2008)

You're right, admittedly, my perspective is based on a controller that can control independent motors simultaneously. This is electronically difficult, not mechanically. The motor itself is fairly easy to build, and the EV community is still struggling to build their own basic dc controllers. However, building gearing into a wheel motor doesn't fix the differential problem dealing with turning, which means you need a controller that can control wheels separately anyways. If you are talking about just not building a wheel motor but a single drive motor with an improved (and purposed) transmission. Then I think that someone should start a separate project for that (ie DIY EV transmission). Its a good Idea, it could help a lot of people, it would definitely help improve the range/efficiency of EVs. But thats not this thread. 
-There are a lot of different projects to be had for EVs, a lot of different design approaches; some reduce weight, some reduce drag, some use ac, some use dc, there are a thousand different battery chemistries and topologies out there. None are best, which is why there are multiple threads on the diy ev forum.
-I like the idea of multiple designs almost competing on this thread for the best wheel motor. I just think it should be confined to DIY wheel motors.
-To the guy who is looking up stator stuff, most of the designs I have seen use M19 silicon steel laminated to a thickness dependent on the design, usually around 4 to 6 inches for a wheel motor. here is a picture I found of a stator, but designs differ obviously, but the basic shapes involved are the same.


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## Schmism (Aug 16, 2008)

wilcorp70 said:


> However, building gearing into a wheel motor doesn't fix the differential problem dealing with turning, which means you need a controller that can control wheels separately anyways. If you are talking about just not building a wheel moto


in my head the best place to start for a first generation wheel motor, is to mount it directly to a center diff. no transmission, no mechanical reverse, 

take a typical rear end diff, and bolt a (whatever size it needs to be) motor right to the face. 

shaft drive the rear wheels. no mechanical rear brakes but provide regen braking off the motor.

this solves differential turn speed issue, eliminates a heavy transmission, still allows you to gear down the motor by a varable amount depending on size/weight variation of the starter vehical.

retain a stock front end, front disk brakes do ~85-90% of the braking required in a stock IC powered car. With proper brake peddle setup, the first "stage" would engage regen brakeing, but as you moved "deeper" into the pedal you gradually increase additional mechanical brakeing. Again a system that could be easly tweaked with software on the regen side and pressure control on a manually hydrolic system (note no vacuum boost)

Another hurdle easily covered by the above method, because there is a mechanical gear setup, its easy to design a mechanical "lock" for parking brake. (actuated pin engaging the ring gear locking both wheels)

IMHO the above hybrid hub motor represents a good (realistic) first step giveing time for materials and motor tech to evolve enough to get something small enough, light enough and a controller to run a true multi hub-motor system.


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## 1clue (Jul 21, 2008)

I think I just ran over the mutant squirrel, you guys are gonna have to try a raccoon next.

The unsprung weight issue is huge. The In terms of "jumping ship" I was never exactly on this one, only the idea of a hub motor works just fine for me since I'm after a 1:1 drive, CV joint linked motor. Same motor, different placement.

FWIW, I'm spending most of my time on a CDROM motor site learning to wind motors. I just ordered some CDROM motor kits just to see what it takes. Sorry I'm not up to the big league yet.

FWIW, there is a 15 kW outrunner helicopter motor which weighs in at 1.9 kg. Turns too fast for what we're after, but it's intriguing nonetheless, and a Suzuki Samurai with one of these on would indeed be a teenage mutant ninja squirrel.


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## xrotaryguy (Jul 26, 2007)

> velocity = speed*mph_fps


Shouldn't this read something like: velocity = speed*direction 

I mean, speed _is_ velocity with the distinction that velocity takes into account direction. Other than that stipulation, the two are identical. Of course, you don't have a direction variable anywhere, so you can use what ever you want there, but you get the idea. 



> mass = weight*lbf_lbm


I'm confused about this line too. Mass is: weight/acceleration_of_gravity

It looks like you have weight multiplied by foot pounds or meter pounds. Is that what I'm seeing there?



> Torque = 877.52 ft-lbf
> Force = 877.52 lbf


What is an lbf? I want to say that this looks like foot pounds. Maybe I am just not used to looking at forces in imperial units. Does the f signify that you are talking about pounds as a measure of force rather than a measure of weight? 

I don't see that you've made any mistakes with this last bit. I'm just confused by the units or notation.


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## xrotaryguy (Jul 26, 2007)

Oh, and I don't see any reason to design the hub motor with a built-in gear reduction. That just adds complexity and frictional losses to a motor that should have been designed to spin at the correct speed in the first place. Generally speaking, anything that can be done mechanically can be done more efficiently and more affordably with electronics... within reason of course. No one is going to suspend his kitchen table electronically rather than attach table legs to it right


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## book_knight (Aug 20, 2008)

xrotaryguy said:


> Shouldn't this read something like: velocity = speed*direction
> 
> I mean, speed _is_ velocity with the distinction that velocity takes into account direction. Other than that stipulation, the two are identical. Of course, you don't have a direction variable anywhere, so you can use what ever you want there, but you get the idea.
> 
> ...



Your velocity equation is technically accurate. In this case speed and velocity are assumed to be in the same direction. Therefore there is no real distinction between the two. I just called it speed and velocity to distinguish the two in the MATLAB script. The velocity equation really shows the conversion from miles per hour (mph) --> feet per second (fps).

Your mass equation is correct. In imperial units there are two expressions for mass (slug and lbm [pounds-mass]). Not sure who came up with the naming (don't really much care), but they decided to name pounds in such a way that "pounds" is used for both force and mass. The distinction is that lbm = pounds-mass and lbf = pound force, where gravity is 32.174 ft/s^2 (equivalent to 9.81 m/s^2). Resulting in: *lbf = lbm*32.174 ft/s^2 *. The equation i lable for mass is really the conversion from lbf --> lbm. 

The varible naming i picked for conversions is: *y = x*before_after* . This says convert *x* which has units of *before *to *y* which has units of *after*.

Torque is foot pounds which is equivalent to Newton meters.

Mainly these units were displayed here (instead of SI units) due to the fact that i want to use this motor on an American car. But i much rather work in SI units, seems so much cleaner.


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## book_knight (Aug 20, 2008)

1clue said:


> FWIW, there is a 15 kW outrunner helicopter motor which weighs in at 1.9 kg. Turns too fast for what we're after, but it's intriguing nonetheless, and a Suzuki Samurai with one of these on would indeed be a teenage mutant ninja squirrel.


Do you happen to have a link to this 15 kW outrunner?


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## Schmism (Aug 16, 2008)

xrotaryguy said:


> Oh, and I don't see any reason to design the hub motor with a built-in gear reduction. That just adds complexity and frictional losses to a motor that should have been designed to spin at the correct speed in the first place. Generally speaking, anything that can be done mechanically can be done more efficiently and more affordably with electronics... within reason of course.


For the most part i would agree. Were I think "we" will run into real problems, is when it comes time to build such a motor with current materials. 

Where technically you COULD build something that meets the mechanical requirements (rpm range, torque, power) i have a feeling the physical requirements (size, weight) are such that makes it completely infeasible to use as a hub motor. 

Inherently there are 2 ways to approach it. 
1) define a physical range of size and weight for the motor that is feasible for a "normal" suspension and build a motor to fit inside that. 
2) build a motor that meets the mechanical requirements and TRY to fit it into some sort of suspension. 

What Id hate to see is a bunch of software and electronic motor geeks build a motor that fits their requirements, bring it to the mechanical engineer who's job it is to put it in a suspension and the mechanic laugh you out of the garage as there is no physical way to make it work. 

*Q: Why didn't you tell us that wouldn't work on the front end!
A: Because no one asked!

*So does anyone have any ball park ideas of the physical size of what you guys would end up designing. (overall dimensions and weight?)

From a mechanical standpoint (make it work in the suspension of a car) its an important design criteria that, up until now, seems to have been, for the most part, overlooked as far as i can tell.


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## book_knight (Aug 20, 2008)

Schmism said:


> So does anyone have any ball park ideas of the physical size of what you guys would end up designing. (overall dimensions and weight?)


My current thoughts on dimensions, please feel free to augment/modify stating reason. the diameter was chosen because Bugzuki already designed some thing to that diameter. Thickness was arbitrary. 

Diameter = 13.5 in.
Thickness = 8 in. (includes all mounting components as well)

Weight dependent on materials used and design. What's the max weight a typical mid-sized car should expect from the wheel? Whats the max weight that a typical mid-sized car suspension can handle?

I was hoping that aluminum would have enough strength for the hub motor's casing if designed using thin wall theory normally employed in aerospace applications. A proper application of such a practice should reduce weight significantly while maintaining strength in key areas.


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## 1clue (Jul 21, 2008)

book_knight said:


> Do you happen to have a link to this 15 kW outrunner?




http://www.plettenberg-motoren.com/UK/Motoren/aussen/Predator37/Motor.htm


I'm not trying to say this thread's project is a wash, not in any way. The thing is though, the more things you design this thing FOR, the more things this project will NOT work for.

Even going to a specific plate size rather than a set of steps after which you get a motor, even that will cause this project to stop being useful for some people. I agree that you sooner or later have to stamp out a plate, but that doesn't mean you have to say how many plates to use. I think it would be great to just offer some plates for sale, by the inch. Want more power? Get more plates, turn your bell a bit larger and put in another layer of magnets.

I think that if someone starts designing gears right into the motor housing I will suddenly lose interest.


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## 1clue (Jul 21, 2008)

I have a thread going on the rcgroups forum about outrunner motors, magnetic gearing etc.

http://www.rcgroups.com/forums/showthread.php?t=912900

It turns out that "magnetic gearing" is misleading. The thing which increases your torque is the diameter of the motor. The number of magnetic poles changes the RPM but not the torque.

Some of you might have known this, but I didn't. I'm just guessing here, but I strongly suspect that some others on this thread didn't either.


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## Schmism (Aug 16, 2008)

book_knight said:


> Weight dependent on materials used and design. What's the max weight a typical mid-sized car should expect from the wheel? Whats the max weight that a typical mid-sized car suspension can handle?


A common misconception concerning the "weight" of the car. In IC cars, the total weight of the car may be the same as an EV car, but the distribution of were the weight is, is significantly different.

Unsprung weigh of most mid-sized cars, is relatively low, you could hold the entire front corner suspension of say a Honda accord, half-shaft, rotor, knuckle, coil-over shock, and trailing arms. The whole assembly probably weighs 80-100lbs

with a hub powered EV you move a significant portion of the vehicals weight to the unsprung side of the suspension. (lets ball park the hub motor at 80lbs) now you have twice the unsprung weight. but it gets worse, because you have so much more mass at the knuckle/hub, you need to make them larger to handle it, the shocks have to be larger to dampen the unsprung weight, the suspension links have to me more heavy duty. 
so by moving more weight out by the wheels you are going to have to add extra weight (in the form of larger biger, beefer parts) to the suspension just to hold it. so now your looking at an assembly that weighs 200+ lbs. 

The reason i showed truck knuckles in the pics i attached, was the weights of the unsprung items are roughly the same. = designs will need to mimic them for beafy-ness in order to hold the extra hub-motor weight.



> I was hoping that aluminum would have enough strength for the hub motor's casing if designed using thin wall theory normally employed in aerospace applications. A proper application of such a practice should reduce weight significantly while maintaining strength in key areas.


The key to the motor casing design is weather or not you decide to make the hub-motor a structural part of the suspension, or just hang it off the backside of a knuckle/hub. If you hang it off a more traditional knuckle hub, then the existing thin wall type motor works fine as it only has to support its own weight (+ or - a few hundred g's of weight when you cycle the suspension "quickly")

if you make it a structural component of the suspension, you have this loop back problem. more weight = biger parts... biger parts=more weight..repeat. bearing placement and design will be key if you go this route as you could potentially wind up with huge moments the bearings have to carry due to offset issues.


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## 1clue (Jul 21, 2008)

One other consideration here is that the suspension will also need to manage torque, which normally is handled inboard at the differential/transmission.


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## John (Sep 11, 2007)

1clue said:


> One other consideration here is that the suspension will also need to manage torque, which normally is handled inboard at the differential/transmission.


 I wouldn't think this would normally be an issue as the suspension has to handle braking torque anyway and this would normally be more than motor torque.


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## 1clue (Jul 21, 2008)

John said:


> I wouldn't think this would normally be an issue as the suspension has to handle braking torque anyway and this would normally be more than motor torque.



I guess you're right. Never mind then.


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## aeroscott (Jan 5, 2008)

1clue said:


> One other consideration here is that the suspension will also need to manage torque, which normally is handled inboard at the differential/transmission.


 all useful torque is handled by suspenion only . all other torque is restrained or wasted in the flex of the system .


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## aeroscott (Jan 5, 2008)

xrotaryguy said:


> Oh, and I don't see any reason to design the hub motor with a built-in gear reduction. That just adds complexity and frictional losses to a motor that should have been designed to spin at the correct speed in the first place. Generally speaking, anything that can be done mechanically can be done more efficiently and more affordably with electronics... within reason of course. No one is going to suspend his kitchen table electronically rather than attach table legs to it right


A guy from LTI said that to get the needed torque with out gearing the motor would get huge . this is using a state of the art switched reluctance motor . smallest wheel motor they make is 400 hp , they are more demanding of high torque then our needs . sr motors run much cooler armature in the high torque low rpm start up mode


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## OHM (Jun 30, 2008)

1clue said:


> I have a thread going on the rcgroups forum about outrunner motors, magnetic gearing etc.
> http://www.rcgroups.com/forums/showthread.php?t=912900
> It turns out that "magnetic gearing" is misleading. The thing which increases your torque is the diameter of the motor. The number of magnetic poles changes the RPM but not the torque. Some of you might have known this, but I didn't. I'm just guessing here, but I strongly suspect that some others on this thread didn't either.


When I looked at the specs of industrial motors I noticed the more poles the less rpm and the more power and torque not the other way around.

However how can this RC motor have 20 poles and have very high rpm, be superlight and make 15kw!!!! WTF

http://www.plettenberg-motoren.com/UK/Motoren/aussen/Predator37/Motor.htm

Cant be used for EVs but confuses me completely on the number of poles and their relationship to power, torque and speed.


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## 1clue (Jul 21, 2008)

OHM said:


> When I looked at the specs of industrial motors I noticed the more poles the less rpm and the more power and torque not the other way around.
> 
> However how can this RC motor have 20 poles and have very high rpm, be superlight and make 15kw!!!! WTF
> 
> ...




RC motors are a whole different class of motor. They use very high quality materials and don't really care how much it costs.

They are also using speed controllers with very high frequencies. The plates they make the stators with are 1/3 mm in some cases, and I have no idea what type of material it's made of. They use neodymium magnets, which are evidently the best magnet you can get.

FWIW, that rpm is lower than most RC models by a significant stretch. The smaller ones are going 20,000 rpm and higher. The limiting factor in the bigger motors are heat of the core, but for smaller ones I guess it's the frequency of the drive creates eddy currents which reduce the torque. The bigger motors would have the same problems if I understand correctly, but they have less surface area per unit volume, which means they can't cool as well.

Most of the motors referenced in projects on this site are industrial motors being modified for use as a high frequency motor. These motors are designed around 60 hz or so. The RC model motors are designed to be used at the RPM found in models, designed for the purpose.


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## aeroscott (Jan 5, 2008)

Schmism said:


> For the most part i would agree. Were I think "we" will run into real problems, is when it comes time to build such a motor with current materials.
> 
> Where technically you COULD build something that meets the mechanical requirements (rpm range, torque, power) i have a feeling the physical requirements (size, weight) are such that makes it completely infeasible to use as a hub motor.
> 
> ...


heavy unsprung weight cars / light trucks have been around for years ( my dodge 4 by 4 ) they work not as good as my Mercedes on a ruff roads , but not that bad.


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## John (Sep 11, 2007)

All unsprung weight is detrimental to the handling of a vehicle but a more pragmatic point of view is that it is the sprung to unsprung weight ratio which determines what is acceptable. Fitting heavy hub motors into a very light vehicle with lithium ion batteries would be much worse than fitting them to a truck with a 2000lb lead acid pack. The down force generated by the suspension on a wheel obviously reflects the weight it is carrying. When the wheel runs off the edge of say a pothole and looses touch with the road it is this force that accelerates the wheel back towards the road and it is the inertia of the unsprung mass that resists that accelerative force. So how long the wheel is off the road is determined to a degree by the ratio of the weight the wheel is carrying (sprung weight) to the wheels unsprung weight. This is a simplification as this also affects the grip variation over undulations in the road surface and the amount of shock transmitted to the vehicle body when a wheel rides over an object on the road or the other side of that pothole. Vehicles with a low unsprung to sprung weight ratio just ride nicer and behave better through corners.


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## OHM (Jun 30, 2008)

1clue said:


> RC motors are a whole different class of motor. They use very high quality materials and don't really care how much it costs.
> 
> They are also using speed controllers with very high frequencies. The plates they make the stators with are 1/3 mm in some cases, and I have no idea what type of material it's made of. They use neodymium magnets, which are evidently the best magnet you can get.
> 
> ...


So forgetting the RC motor for a second, you are saying that the poles only control the speed not the torque in your previous post.

Now if thats the case why no use a same weight and diameter 2 pole version of an equivalent 4 pole industrial motor straight off with its higher rpm? Is it due to better speed and efficiency control for an ev?


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## aeroscott (Jan 5, 2008)

1clue said:


> RC motors are a whole different class of motor. They use very high quality materials and don't really care how much it costs.
> 
> They are also using speed controllers with very high frequencies. The plates they make the stators with are 1/3 mm in some cases, and I have no idea what type of material it's made of. They use neodymium magnets, which are evidently the best magnet you can get.
> 
> ...


the best of the industrial inverter rated / high efficiency will have very thin lamination's . that will keep induction heating down as we get closer to 400 cps (hz) . how thin i need to check .


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## 1clue (Jul 21, 2008)

OHM said:


> So forgetting the RC motor for a second, you are saying that the poles only control the speed not the torque in your previous post.
> 
> Now if thats the case why no use a same weight and diameter 2 pole version of an equivalent 4 pole industrial motor straight off with its higher rpm? Is it due to better speed and efficiency control for an ev?



That's what I currently understand to be true.

Obviously, if you can get adequate torque with direct drive, then that's best for the application. The whole problem with RC planes is that the motors turn so blinking fast. They went with outrunner motors because they can direct drive the props with them. Same thing with ceiling fans.

I spent a while trying to figure out why you never see outrunner motors on industrial equipment. I think this might be it. With industrial equipment, they generally gear or belt drive the load, and if they go with a lower rpm motor it's usually both in a place where the weight doesn't matter AND in a place where noise does matter. I suspect that the lower RPM means they can use cheaper materials.

I don't have an authoritative source for this, but I do have discussions from guys on rcgroups.com who are designing their own motors and seem to be teaching the world how to do it. So far, everything they say makes sense of the question and clears up a few more every now and then too, that I never got around to asking.


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## Schmism (Aug 16, 2008)

John said:


> All unsprung weight is detrimental to the handling of a vehicle but a more pragmatic point of view is that it is the sprung to unsprung weight ratio which determines what is acceptable. Fitting heavy hub motors into a very light vehicle with lithium ion batteries would be much worse than fitting them to a truck with a 2000lb lead acid pack. The down force generated by the suspension on a wheel obviously reflects the weight it is carrying. When the wheel runs off the edge of say a pothole and looses touch with the road it is this force that accelerates the wheel back towards the road and it is the inertia of the unsprung mass that resists that accelerative force. So how long the wheel is off the road is determined to a degree by the ratio of the weight the wheel is carrying (sprung weight) to the wheels unsprung weight. This is a simplification as this also affects the grip variation over undulations in the road surface and the amount of shock transmitted to the vehicle body when a wheel rides over an object on the road or the other side of that pothole. Vehicles with a low unsprung to sprung weight ratio just ride nicer and behave better through corners.


basicly that big long complicated paragraph reads. 

Trucks ride rough "like trucks" but when you put 1000lbs of load in the back they actually ride much much better. (almost car like)


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## aeroscott (Jan 5, 2008)

Schmism said:


> basicly that big long complicated paragraph reads.
> 
> Trucks ride rough "like trucks" but when you put 1000lbs of load in the back they actually ride much much better. (almost car like)


most of the ride improvement is due to the springs coming into working range . many trucks run airbags vastly improving ride quality . you can feel the unsprung weight its just not a deal breaker .


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## Bugzuki (Jan 15, 2008)

1clue said:


> Even going to a specific plate size rather than a set of steps after which you get a motor, even that will cause this project to stop being useful for some people. I agree that you sooner or later have to stamp out a plate, but that doesn't mean you have to say how many plates to use. I think it would be great to just offer some plates for sale, by the inch. Want more power? Get more plates, turn your bell a bit larger and put in another layer of magnets.


I guess I can not state this enough. I am trying to make my design scalable, but I have to start somewhere. I can not make a scalable design and not make a specific size to start with. I chose 13.5 or so inches because I thought it would be in the middle of the range that people might want. The larger the diameter the more power.



Schmism said:


> A common misconception concerning the "weight" of the car. In IC cars, the total weight of the car may be the same as an EV car, but the distribution of were the weight is, is significantly different.
> 
> Unsprung weigh of most mid-sized cars, is relatively low, you could hold the entire front corner suspension of say a Honda accord, half-shaft, rotor, knuckle, coil-over shock, and trailing arms. The whole assembly probably weighs 80-100lbs
> 
> ...


Sorry, but I do not agree with this statement. I think you are looking at it the wrong way.

Unsprung weight is held up by the ground, while the suspension holds up the car. Putting a motor in the wheel does not mean that you will have to rebuild all of the suspension components. Yes, you might have to get shocks with a different damping ratio to damp the unsprung weight, but the rest could be fine. 

The beefy axles of trucks are that way not to hold themselves up but to hold up the heavier vehicle. Technically the suspension does not care how much the axle weighs since the axle holds up the suspension.

Most EVs end up weighing more then the original car, so adding some unsprung weight might not be a huge issue since the sprung/unsprung ration changes. Engines and transmissions usually weigh less then 500 lbs, compared to however much your battery pack weighs - plus all of the bracketry to hold the batteries. Yes, there are other things you take out, but there are other things you put back in.

About the motor casing. No matter where you mount the hub motor it has to support the entire car. That weight is transfered through the motor housing if it is an outrunner or inrunner design. It does not matter if you make the motor an integral part of the suspension or mount it to the existing hub. It still needs to hold the entire weight of cornering a vehicle. It will never see just it's own weight (unless you always run your car on jack stands). 

There is no way you could get a system to work by mounting to the exist hub anyway. The hubs are designed to be at the mid point in the wheel (most of the time). If you attach a hub motor to that then attach a wheel the mid point has now moved outward by 4 to 8 inches. This will add a ton of torsional stress to the original knuckle that it was not designed for. Not because the motor weighs 80lbs but because the car body is apply the force to the suspension differently.

*All I can say is design the housing to hold the weight of the car not it's own weight.*



aeroscott said:


> A guy from LTI said that to get the needed torque with out gearing the motor would get huge . this is using a state of the art switched reluctance motor . smallest wheel motor they make is 400 hp , they are more demanding of high torque then our needs . sr motors run much cooler armature in the high torque low rpm start up mode


We are not talking about getting 400 hp. You can get good power out of small motors. Motors have full torque at zero RPM. So, I am hoping there will be enough. I might be wrong, and if I am I will work on a gear reduction. But, that will add a ton of complexity and cost to the motor and so, I would prefer to see if we can do it without the reduction first.


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## 1clue (Jul 21, 2008)

Unsprung weight is a well-known and well-mapped phenomenon. http://en.wikipedia.org/wiki/Unsprung_weight

The more unsprung weight, the worse the car handles. The only thing you can do about that is reduce the unsprung weight, and improve the action of the suspension.


There is no reason why the motor should have to hold the weight of the car. There can be a bearing outboard of the motor, or even two with a coupling to the motor.


Electric motors can supply full torque at 0 rpm, but how long can the same exact winding maintain the full current load without melting? How long can one phase of the controller maintain full current, with the gate device wide open? Amplifiers and similar devices rarely can put out DC for any length of time without overloading. Not really sure how a motor controller works, but I'm fairly sure it's not going to like 10 seconds of full power with no wheel movement.


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## Bugzuki (Jan 15, 2008)

I have not posted in a couple days, since I am working on researching how to actually design the motor. I have found some formulas for 3ph AC induction motor design:

Synchronous Speed of Stator: Ns = 120*(f/p) 

Ns = Speed of flux rotation in the stator
f = supply frequency
p = Number of poles on the stator
Base speed (Nb) -> stable speed at which the rotor turns with a given stator synchronous speed - determined by the load applied.

Slip is the difference between Ns and Nb -> varies with load: 
%slip = ((Ns - Nb)/Ns)*100

I do not really understand the Torque equations I found:

T = kBIr
B = amplitude of the flux density wave
Ir = amplitude of the rotor current wave

T-Tl = J(dWm/dt)=Wm(dJ/dt)
T = instataneous value of the developed motor torque
Tl = instantaneous value of the load torque
Wm = instantaneous angular velocity of the motor shaft (rad/sec)
J = Moment of enertia of the motor/load system

I got those equations from the book _Electric Motors and Drives_ and from a Microchip paper. Here is a quote from _Electric Motors and Drives_:

"The induction motor develops torque by the interaction of axial currents on the rotor and a radial magnetic field produced by the stator. ... The torque-porducing currents in the rotor of the induction motor are induced by electromagnetic action, hence the name 'induction' motor. The stator winding therefore not only produces the magnetic field (the excitation), but also supplies the energy that is converted to mechanical output." 

I have yet to find an exact description on how to setup the motor stator winding.


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## Bugzuki (Jan 15, 2008)

1clue said:


> Unsprung weight is a well-known and well-mapped phenomenon. http://en.wikipedia.org/wiki/Unsprung_weight
> 
> The more unsprung weight, the worse the car handles. The only thing you can do about that is reduce the unsprung weight, and improve the action of the suspension.


I agree with your statments about unsprung weight. But, we have yet to see how much effect we will make - or any formulas to help us determine the effect.



1clue said:


> There is no reason why the motor should have to hold the weight of the car. There can be a bearing outboard of the motor, or even two with a coupling to the motor.


With both of the designs I have seen so far (mine and Book Knight's) they would both need the housing to be able to hold the weight of the vehicle. If we designed an outrunner where the stator did all of the load caring and the housing saw none of it that would be different. It would take having a double bearing on the outside of the stator that the wheel bolted to. This bearing would have to be stable enough to keep the airgap from fluxuating.

But no matter how you look at it some part of the motor will have to support the weight. We can not take a huge truck axle with at long hub shaft and put it in our passenger car.



1clue said:


> Electric motors can supply full torque at 0 rpm, but how long can the same exact winding maintain the full current load without melting? How long can one phase of the controller maintain full current, with the gate device wide open? Amplifiers and similar devices rarely can put out DC for any length of time without overloading. Not really sure how a motor controller works, but I'm fairly sure it's not going to like 10 seconds of full power with no wheel movement.


Your right I was not thinking about the time it can handle the torque. If you are doing a lot of hill travel it might overheat a motor. But if you make a motor fit the car it should be able to handle it. That also brings us back to my statement that if we find a gear reduction is needed we can design one at that point. Why make the design more costly if it is not needed?

Thanks for getting back so quick.


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## 1clue (Jul 21, 2008)

Bugzuki said:


> I agree with your statments about unsprung weight. But, we have yet to see how much effect we will make - or any formulas to help us determine the effect.


I don't have them. It's gotta be plain physics though, you have a mass moving in such a direction at such a speed, you hit a bump (tire pressure fluxuates, causing an increase in force related to the change in volume) the suspension gets a force on it, starts accelerating based on the force and its mass, etc.


> With both of the designs I have seen so far (mine and Book Knight's) they would both need the housing to be able to hold the weight of the vehicle. If we designed an outrunner where the stator did all of the load caring and the housing saw none of it that would be different. It would take having a double bearing on the outside of the stator that the wheel bolted to. This bearing would have to be stable enough to keep the airgap from fluxuating.
> 
> But no matter how you look at it some part of the motor will have to support the weight. We can not take a huge truck axle with at long hub shaft and put it in our passenger car.


No, it doesn't. I tried to make a pdf but my simple drawing was 25k, this site only allows 19k for that size. It wasn't a very good drawing anyway, so you're not missing much. You'll have to live with a description:

So you have a vertical plate with an axle through it on bearings. The suspension A-frames hook to the plate. The inboard side of the plate, the shaft has a spline on it. The outboard side, the shaft has a wheel. In other words, this is a standard suspension that would get a CV joint hooked up to it, only it's a spline and the A frames are further apart.

The motor hooks up to the spline and bolts to the plate. Or you have two plates, or one plate and spacers to make everything work.

This is almost certainly not an optimal way to do it, but it is ONE way that the motor would not need to bear the weight of the car. Somehow it makes me very nervous that the motor would do that, especially when close tolerances are desirable inside the motor.



> Your right I was not thinking about the time it can handle the torque. If you are doing a lot of hill travel it might overheat a motor. But if you make a motor fit the car it should be able to handle it. That also brings us back to my statement that if we find a gear reduction is needed we can design one at that point. Why make the design more costly if it is not needed?
> 
> Thanks for getting back so quick.


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## Bugzuki (Jan 15, 2008)

I understand there is a lot of physics in volved. But, there is also a lot of human factors involved as well. That is where some formula or testing comes into play. Thinking about how everything works in the perfect world is great, and might get us close. The final say is how it feels to your backside. We will need to talk about the unsprung weight, but we first need to get a design and start proving it out. 

So, I think that we should hold off on the discussion for the time being. at least until we can come up with a motor weight.

I did not really understand your description (I can be a little dense sometimes). It sounded like we were trying to say a similar idea about the stator shaft mounting to the upright then the hub mounts to the shaft - with the rotor mounting to the hub. The hub/shaft would support the weight of the vehicle into the upright. The hub bearing would have to be stable enough to keep the rotor from moving. Is that what you were discribing?

I am going to the Fair now, be back later.


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## 1clue (Jul 21, 2008)

Bugzuki said:


> I understand there is a lot of physics in volved. But, there is also a lot of human factors involved as well. That is where some formula or testing comes into play. Thinking about how everything works in the perfect world is great, and might get us close. The final say is how it feels to your backside. We will need to talk about the unsprung weight, but we first need to get a design and start proving it out.
> 
> So, I think that we should hold off on the discussion for the time being. at least until we can come up with a motor weight.


How it feels to your backside: Car companies have been fighting unsprung weight for decades now. The sports car makers are fighting it much, much harder and they go so far as to make featherweight rims just for handling purposes. A friend of mine had a BMW M3 Lightweight some years back, and he had some spare rims with it. I could pick that rim up with my pinky and hold it for several minutes. Those rims, if he was to be believed, cost $1000 USD each. That's how much that particular company disliked unsprung weight. Other companies have less gusto, but still don't add any unsprung weight that isn't necessary, they just don't go out of their way to use the lightest materials.



> I did not really understand your description (I can be a little dense sometimes). It sounded like we were trying to say a similar idea about the stator shaft mounting to the upright then the hub mounts to the shaft - with the rotor mounting to the hub. The hub/shaft would support the weight of the vehicle into the upright. The hub bearing would have to be stable enough to keep the rotor from moving. Is that what you were discribing?
> 
> I am going to the Fair now, be back later.



I'm not sure if I understood your description of my description. 

Take a look at some of the outrunner RC plane motors. They have a stator which is hooked to a mounting bracket. That bracket bolts to the plane's firewall. You can either mount the prop to the bell which spins, or you can mount to the shaft which sticks through the mounting bracket.

My description is of a spline on the shaft which sticks through the mounting bracket. That spline slides into an axle's mating spline, and the axle itself bears the weight.

Look at all these motors that people use for conversions. The manufacturers seem to go out of their way to make it difficult to hook anything to the motor. The shaft is tiny, and inset, and splined. So they obviously want you to make a coupling for it rather than hook some massive pulley up and assume the motor's bearings will take the load. I think that at these torque levels, the motor can flex itself enough to rub the stator against the rotor if the load pulls to one side. Why else would they go through all that trouble to make the shaft tiny and splined? It would be super simple to just put a big honking shaft on there that sticks out 6 or 8 inches and let you put whatever on it.


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## Schmism (Aug 16, 2008)

Bugzuki said:


> About the motor casing. No matter where you mount the hub motor it has to support the entire car. That weight is transferred through the motor housing if it is an outrunner or inrunner design. It does not matter if you make the motor an integral part of the suspension or mount it to the existing hub. It still needs to hold the entire weight of cornering a vehicle. It will never see just it's own weight (unless you always run your car on jack stands).
> 
> There is no way you could get a system to work by mounting to the exist hub anyway. The hubs are designed to be at the mid point in the wheel (most of the time). If you attach a hub motor to that then attach a wheel the mid point has now moved outward by 4 to 8 inches. This will add a ton of torsional stress to the original knuckle that it was not designed for. Not because the motor weighs 80lbs but because the car body is apply the force to the suspension differently.
> 
> *All I can say is design the housing to hold the weight of the car not it's own weight.*


I think it is a much better design to hang a motor off the back side of an existing knuckle suspension design. The same way the CV stub shaft supports no weight of the car and only transmits engine power to the axle (the part that is inside the bearing that is carrying the weight of the car) but the stub shaft and CV joint carries ZERO vehicle weight.

take that same design and instead of having a CV stub shaft supplying the rotational force, you bolt a motor in its place. In this case, the motor (just like the cv stub shaft) carries 0 vehicle weight. 



> I might be wrong, and if I am I will work on a gear reduction. But, that will add a ton of complexity and cost to the motor and so, I would prefer to see if we can do it without the reduction first.


while a perfectly valid approach. From my point of view you only risk all the time taken to develop a non-geared version. geometry, suspension design etc. All of those items, shape of motor, size of motor, mechanical caricaturists (proper RPM range), suspension design IS going to change, should you need a gear reduction.

I suppose the big question is, how much work has to go into a non-geared version before there is a go/no-go call. Can that call be made without actually building a prototype?


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## feyrerm (Aug 27, 2008)

I am new to this site and found this thread. What you are trying to do is really awesome here. To be able to basically hybrid any car is a Noble cause and should be pursued. I was looking into hub motors long before I stumbled onto this site. Please have a look at this site.

http://www.otherpower.com/turbineplans.html

It had detailed instruction on cheap simple to build pancake turbines. From what I know about electric motors these could serve the function as electric hub motors with the right controller. They are easily scalable and use simple material as well.

I hadn't seen anyone mention this type of motor and was just wondering it there is something I am overlooking here.


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## itjstagame (Aug 27, 2008)

Nice thread, very good read. You actually had some really good conversation in the middle.

Anyway, not to restart the different viewpoints, but here are my thoughts. If you look at most DIY EVs now, people are buying giant motors, controllers and battery packs and hooking to existing driveline. If you really want to be open source and help the EV movement than I think you should start looking there. I feel that the controller or inverter is the most expensive part and next the batteries depending on how many and what type. But I really like the idea of focusing on an open source, scalable, multipurpose controller/inverter. If you can get a company to cut your PCB design (which isn't hard) you can get to megasquirt level. People can now buy their system (or just the pcb board and plans and then find all electronics seperately) and for <$200-300 they can have a $1000+ EFI system that's more tunable and controlable. If we can do this this would be awesome.

The other big thing is the
motor, this is the most common one I see in use from kits: http://www.evparts.com/prod-MT2141.htm I don't see anywhere where it says brushless (unless ADC stands for alternating DC and implies brushless) and talks about brushes. IF this is a brushed DC motor that is horribly inefficient. A brushless DC or AC will provide much more efficiency and if there could be a kit or plans to buy a particular stator and housing and wind yourself from copper and put it all together for significantly cheaper (say shoot for $300-500) then that'd be awesome. Do you see what I'm trying to do, we want to allow hardcore DIYer's to have a fairly easy way to convert a car but for MUCH cheaper than a $17k kit. $17k is rediculous, I think for most people to start consider converting their own car they'd want to see at least 80-100MPH as possible and at least a 50-100 mile range and I don't think it can be more than $5k and even that seems high.

So please keep working on that controller and we can hound the RC guys for suggestions of proper sizes and strengths and how to make a good size and efficient motor. After reading their site you can't help but really want to go outrunner brushless DC, they can pack their motors into much smaller and lighter packages and they rev much less (and for direct drive we want much less revs). There's one good link I read where a guy had a 6HP brushless DC RC motor and put it on his bicycle, the thing was a little bigger than a soda can and could probably easily have made him go 45+MPH (he limited it to 35 but had much more power there). And another on the RC boards has used a only alternator from a car to drive his motorcycle. If you're really stuck on using inrunner AC then making something to use an old alternator wouldn't be bad. They don't put out a super amount of power but if you had one on each wheel it'd be plenty. Plus he found he can control starting torque and max rpms with varying voltage on the inner cage.

I think after you have both of these items and a huge following you can move on to hub wheels and where and how to mount them, etc. I realize that the where and how could dictate the size and structure of the motor but it's not that hard to redesign the motor after the fact just to change the packaging as long as the controller can control either.

Last thing that I'm tired of reading the debate on it sprung/unsprung. Maybe with an AC motor I could see this being an issue, but have you held an alternator? Even at twice the weight I'm sure they're less than 50lbs, so why are we stating 100-200lbs? Plus if we used brushless DC it'd be quite a bit less. Magnets are light. Enough magnets for a good size motor (either 13" diameter x 1" width or 6" diameter x 2" or whatever you end up with) would stuggle to be 10lbs, and that's ferrite, neodyns are much lighter, I'd bet 3-5lbs for the motor size we want for a hub motor. Plus go look at the prices, 3-5lbs of neodyns is $100-150. Compared to that $1700 motor I just showed I don't know how you can say that's expensive or too costly. Would you rather price 30lb of copper wire? Of course you still need copper for the stator and that would be unsprung but I'm estimating that'll be less than 30lbs, I mean a big box of 100ft of house wiring (is that 4 gauge or 8 gauge?) Either way they don't weight 30lbs. Say 50lbs max, still about 50lbs overall.

Last big advantage of brushless DC, even if it ends up weighing 50lbs total for the motor and all of that weight is unsprung, it will NOT all be rotational inertia. I saw one person's concern about turning and stopping and whatever, but the stator with the huge amount of copper does not spin and will not create any inertia to overcome in steering. The only rotational weight you're adding is 5lbs of magnets.

And the final thing I want to say, I have no problem with keeping mechanical brakes if you really want to, but there is no need. It does not matter what speed, how slow or stopped or whatever, if you're drawing from a motor it will have a load and it'll slow down. Heck if you're doing BLDC it has strong forces to force it to go whatever speed you're sending from the controller's PWM, if you set it to 0 the tires will lock up and skid. As long as you can let the regen controller control how many amps it's allowed to see and attempt to draw and have large resistors or capacitors incase the battery is full then you'll be fine. Calculate your worst hill (maybe 60 deg slope) and heavy car (4k lbs) / 4 for 4 wheel motors and each motor will have 866 lbs of potential energy force, I'm not good with converting that to watts or Ns but as long as you can have the controller trying to draw more than this and able to (wiring size, etc), the car won't move.

Having both systems to me seems like having two seperate hydralic brake systems in a car just incase one fails. Although I guess we should look at rates of failure of the electrical system and regen braking compared to hydralic before I bite off more than I can chew here.


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## Schmism (Aug 16, 2008)

itjstagame said:


> Even at twice the weight I'm sure they're less than 50lbs, so why are we stating 100-200lbs? Either way they don't weight 30lbs.


the number i tossed out of 200 lbs was the total unsprung weight.

i ball park'd the potential hub motor at 70-80 lbs.

as the warp 9 seems very popular, and weighs 130-156lbs, (ive seen both figures for weight) as we need at least 2 motors our performance per motor is half, so i assumed half size= half weight as a place to start.


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## judebert (Apr 16, 2008)

My ADC 9" (on which the Warp was based) weighed nearly 150# with half the copper removed. I'd bet it's more like 180 now that it's all put together.


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## OHM (Jun 30, 2008)

judebert said:


> My ADC 9" (on which the Warp was based) weighed nearly 150# with half the copper removed. I'd bet it's more like 180 now that it's all put together.


What is this youve been hiding a hybrid masterpiece!? please elaborate


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## judebert (Apr 16, 2008)

OHM said:


> What is this youve been hiding a hybrid masterpiece!? please elaborate


Ummm... Gee, I wish. The copper in my motor was suddenly, inadvertently, and *forcefully* removed.

I just know how much it weighed because I had to ship it to Oregon for Jim Husted to rebuild it. And it weighed more when he shipped it back.


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## OHM (Jun 30, 2008)

judebert said:


> Ummm... Gee, I wish. The copper in my motor was suddenly, inadvertently, and *forcefully* removed.
> 
> I just know how much it weighed because I had to ship it to Oregon for Jim Husted to rebuild it. And it weighed more when he shipped it back.


Oh I thought that perhaps you turned one into some kind of magnetized version without brushes.


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## tirebiter (Sep 9, 2008)

I just spent the better part of two hours reading most of the posts in this thread. This is the hub motor/wheel motor thread, isn't it ? Why does anyone bring up anything that does not stay at the wheel ?

Unsprung weight will probably be greater than without a wheel motor. Will that cause any problems ? Yes, absolutely and moreso over very rough terrain. How much of a problem ? Not much ! Regardless, this thread is titled hub motor/wheel motor. Why is anyone bringing up anything against it in this thread ?

Alloy wheels have dropped significantly in price. HUGE diameter wheels (20") can be had and super low profile (25 series) tires are more commonplace every year. Believe it or not, the alloy wheel typically weighs less than the rubber tire, with these combinations.

Leaving the stock braking system intact is an easy way out. It's also a very good safeguard to keep in place, considering the experimental nature of building a DYI wheel motor with regenerative capabilities. Using larger than stock diameter wheels provides space for a stator and magnet array between the wheel and the brake rotor and caliper. The brake caliper mouning bracket could be modified to provide a mount for the stator. The magnet array could be glued to the inside diameter of the wheel.

The largest diameter stator the better, in my opinion. It would equate to more tourque and the control system would provide for adequate top speed. Is it possible for those who insist a wheel motor is not the right idea to just keep out of this discussion so those of us wanting to know about a wheel motor will not have to scan your posts and instead get on with the idea of learning about how to build such a device ?


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Bowser!
> "I've built quite a few and all parts were other people's junk.(except the neodymium magnets) Ranging from tiny one ounce 20 000 rpm(for fast planes) to running my bycicle down the road(cadillac blower motor rewound and fitted with neo mags) the last one I built never even made it on anything because I don't have a controller big enough to exploit the potential of the motor.(8 pound motor using ceiling fan stator) The model world is up to 12 KW out of a 3.5 pound outrunner motor(plettenberg predator) I know source for big enough stator(the only part I cant make) to power a car but again, no controller. so just because I could build a brushless motor next to free to power a car does not mean it's the best way to go(for me anyways) When models have a 40KW controller available that is AFFORDABLE you bet I'm building that motor" Barna


Hey any chance of seeing a pix of that motor you are building using the stators from a ceiling fan, I am looking at a good sized hub motor too and know the ceiling fans are described as being either 188 x 20 or 25mm, or else 153 x 15 or 18 or even 20mm and have even found some with 177 x 20mm stators, but what did you use...just so the rest of us young guys can learn some more from an good old guy like yourself....lol !!


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## 3dplane (Feb 27, 2008)

Hey Dave!
You must have pelepathic powers because I'm loading pics on the computer as we "speak".
Now here is my question: Can I just attach files and it will be a clickable jpg ? or how do we do this? Us old guys are not real good with this computer stuff . I'm afraid the pics are gonna be huge and it will piss people off. Pm me with help on instructions.(anyone) Thanks Barna


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## daveinsingapore (Jul 17, 2008)

hey should be no problems, if your pix a big one, then just resave it as a smaller file....this site has a limit of 19.5kb....but no matter, we all can use our imagination any how....here is a small pix of a fan motor...side elevation, but I want to see the stator only.....for the pix just use the attachment icon...the paperclip thingy....have fun...


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## 3dplane (Feb 27, 2008)

Ok I have no clue if the pics made it,lets see.


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> View attachment 785
> 
> 
> View attachment 786
> ...


 of course they made it ...and they look good too...a bit small to run a car as a hub motor and a bit too big to run a RC plane...but some where in between a cycle and a scooter size....have you tried using a RC airplane controller....at least there is no need to use Hall sensors with RC controllers....good work.......


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## 3dplane (Feb 27, 2008)

Yes I used rc controller.The smaller one carried me (6' 4"- 230lb) on a bike using a CC (castle creations) phoenix 25! (25 amp) untill the mosfets fell off the board lol. Weird thing is the poor little controller failed when I let off and was coasting. I think the capacitors get overcharged from regen.
When I hook the big one up to a controller even with just a half a hand twist on the rotor causing it to go from "free spin" to drag where it's hard to turn and I think that is what would kill (coasting) even a stout controller unless something is done to prevent that.( sprag clutch etc.)
Or electronically solve the issue (freewheel diodes whatever)
Barna


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Yes I used rc controller.The smaller one carried me (6' 4"- 230lb) on a bike using a CC (castle creations) phoenix 25! (25 amp) untill the mosfets fell off the board lol. Weird thing is the poor little controller failed when I let off and was coasting. I think the capacitors get overcharged from regen.
> When I hook the big one up to a controller even with just a half a hand twist on the rotor causing it to go from "free spin" to drag where it's hard to turn and I think that is what would kill (coasting) even a stout controller unless something is done to prevent that.( sprag clutch etc.)
> Or electronically solve the issue (freewheel diodes whatever)
> Barna


lol..yeah it would have been funny seeing those little mosfets fall off of the the board when you coasting..the problem is the back EMF....in the natural regeneration mode, and the poor 'little phoenix' certainly flew too close to the sun that day and got it's wings clipped....have you tried with a bigger controller, say 60 or even a 80....I had plans on using a 100amp ESC for one of my projects, was going to use a shop bought outrunner....but am now going to make a motor myself first then go back for a controller. 
As for the back EMF...there are solutions to that including diodes in the right place and larger capacitators, but foremost it the size of the controller...those 25amp models were made to be flown on really small model aircraft not meant to drag big guys like you and I around on two skinny wheels...lol...I am 6'1" and 225lb.....no matter as long as we always have fun.....ciao for now Barna....


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Hey Dave!
> You must have pelepathic powers because I'm loading pics on the computer as we "speak".
> Now here is my question: Can I just attach files and it will be a clickable jpg ? or how do we do this? Us old guys are not real good with this computer stuff . I'm afraid the pics are gonna be huge and it will piss people off. Pm me with help on instructions.(anyone) Thanks Barna


by the way Barna.....your mental 'telepathic' powers are right on que, never doubt them you old timer....lol....BTW..it's old buggers like you that keep young buggers like me in there place....right behind ya....where we belong...lol


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## WheelMotor (Sep 16, 2008)

*affordable execution*

I have the equipment to produce affordable wheel motors. Since the technology is low tech, I don't see any point in secret development. Anybody can buy a wheel motor open it and see how it's made. We can't stop the competition anyway. So this open source approach works fine for me. I guess that making a prototype in an expensive country like the USA or Europe will be very expensive and not in the reach of most of us. But in Egypt, where I have a factory, I can afford. 

For those who don't have a complete metal and winding workshop at their disposal I could, at very low cost only for the forum members, do the "materialisation" 

I don't want to discuss in this thread any commercial aspect, but please feel free to discuss this here in the commercial section: *In Wheel Motor ... affordable*


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## judebert (Apr 16, 2008)

I've started making some progress on the controller software. I'm building a Java prototype, with an oscilloscope-style output, just to verify that I'm not totally misguided. (Don't be concerned with the choice of language; it's just a prototype. Consider it pseudocode, that I can easily translate into C or even BASIC.) I think it's really neat looking; as soon as I get the graphing package updated, I'll post an example. 

I have a couple of questions that you motor designers may be able to answer, since they're not very well covered in the technical documents I've seen. I've already admitted I'm a big n00b to motors and motor design; my bailiwick is programming. I've managed to figure out what's going on with all the force-vector algorythm, but I've still got some hardware questions. (Caution: technical discussion ahead!)

#1: Where can I find the formula that magically translates the stator voltages to stator currents? In the controller loop, I have to read the stator currents; I use a PID controller to turn those into stator voltage outputs. But in the motor, somehow that gets converted back into a current. I might be able to figure this one out from the open-loop version of the controller, but I'm not allowed to look at their code, and I'd rather get a good model than try to derive an equation backwards.

#2: How can I model slip? I suppose I could just modify the existing motor speed by some amount of the new stator vector, depending on its magnitude and the simulated motor load. Again, I might be able to figure this out from the open-loop version, but I'd really rather get a good model (and a good understanding).

#3: Where does the regenerative energy go? I know that it's proportional to the slip, so I can just slow down the "rotation" of the stator fields, but I don't see how I can both power the stator and drain energy from it. Is this something that will be handled in the hardware of the controller, or do I need to do something in the software?

Thanks!


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## Bugzuki (Jan 15, 2008)

Judebert,

That is cool you are making some progress on a controller. I think the problem we are going to run into throughout this project is lack of information. I think that motor design and control is a pretty tightly kept secret. Like when chevy got rid of some of the EV1s to schools they took all of the controllers out so that no body could find out there secrets.

I will try to give some light to your questions, but I am far from being an expert.

The speed and power of an AC motor (be it AC induction or BLDC) is controlled by the applied Frequency and voltage. The applied frequency is the main contributor to the rotor rpm while the voltage is the main contributor to how much torque is created by the slip at that given point in time. *** Please correct me if I am wrong ****

#1 I do not know if there is a formula, but the current is a function of the applied voltage/frequency compared to the amount of slip. As the slip decreases for a given applied voltage/frequency the current decreases - until the point where you start down a hill and the rotor wants to turn faster then the applied voltage/frequency. The motor in then in regeneration.

2# I don't think at this time we would be able to model slip. That would be dependent on the motor, load and what ever else. A better way might be to start off by modeling the characteristics if there was a given amount of slip. Like at the instant you start the motor there will not be any rotation on the rotor but the voltage/frequency will be applied so Slip will be the greatest. Then for running slip we might have to look at various motor spec that are on the market and try to come up with an average percent slip.

3# The energy from regeneration has to go back into the battery through the controller. So the Software would have to recognize regen and switch the control circuitry to allow the current back to the batteries. It might be good to just start of with having the software watch the applied RPM and comparing that to the Actual RPM and adjusting the Voltage/Frequency to make it so there is an equalization of current. Then when the design progresses we can add the circuitry to handle the regen.

I think Madmac is a long way towards actually making a controller prototype. His design has a lot included like regen. It would be nice if he let others help


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## samborambo (Aug 27, 2008)

judebert said:


> #1: Where can I find the formula that magically translates the stator voltages to stator currents? In the controller loop, I have to read the stator currents; I use a PID controller to turn those into stator voltage outputs. But in the motor, somehow that gets converted back into a current. I might be able to figure this one out from the open-loop version of the controller, but I'm not allowed to look at their code, and I'd rather get a good model than try to derive an equation backwards.


OK, I haven't had a chance to flick back the last few pages and catch up but I'm assume we're running with the BLDC idea and ditching Induction.

Stator voltage is made up of 3 components: Back EMF, Winding resistive volt drop and winding inductive reactance (if any). Back EMF is the motor voltage constant, Kv, multiplied by the rotational speed (in rpm or rads/s - you need to know this value). Winding resistance voltage is just the current multiplied by the resistance. Inductive reactance is a vector addition to the resistance, forming the impedance. Inductance is an undesirable factor in the motor and is the result of the magnetic circuit "short circuiting" through free space instead of passing through the rotor - usually because of a large air-gap between the stator and rotor.

Careful with current direction here. When the machine is motoring the impedance volt drop adds to the BEMF. When it is generating, the Z volt drop subtracts from the BEMF. Losses are like taxes - you lose both ways.

This will become important when you need to convert from a torque (current) to a voltage to drive the motor since this is the value the switching devices work from. Stator phase voltage is the difference in duty cycle between IGBT phases multiplied by the DC bus voltage when motoring.

Remember, you're designing a torque controller, not a speed controller as found in industrial applications. Accelerator and brake pedals are torque controls. 



judebert said:


> #2: How can I model slip? I suppose I could just modify the existing motor speed by some amount of the new stator vector, depending on its magnitude and the simulated motor load. Again, I might be able to figure this out from the open-loop version, but I'd really rather get a good model (and a good understanding).


Slip is an induction motor term. BLDC doesn't have slip. If a BLDC skips and electrical cycle, it is considered a stall condition. BLDC motors have a vector angle (or lagging angle) which is proportional to torque. BLDC motors fight hard to maintain synchronous speed. As a motor approaches stall conditions, think of it like a transformer with the secondaries shorted. Pretty much the only thing limiting current flow is the saturation of the iron core.

You'll need hall effect sensors or a shaft encoder for the vector angle. Sensorless vector drive methods rely on the BEMF of the undriven winding to work out the position of the rotor. This is useless when the rotor is at rest or very low speed and will probably result in unpredictable jerky behaviour.



judebert said:


> #3: Where does the regenerative energy go? I know that it's proportional to the slip, so I can just slow down the "rotation" of the stator fields, but I don't see how I can both power the stator and drain energy from it. Is this something that will be handled in the hardware of the controller, or do I need to do something in the software?


There are two ways that current can move in reverse through the switch device. First is the DC bus being a lower voltage than the BEMF due to the 6 diodes around the IGBTs acting as a 3 phase rectifier. Secondly is when the IGBTs act as a synchonous boost converter to "push" the current up on to the higher voltage DC bus, relying on the inductance of the windings as the boost inductor. The second occurs when you commutate the stator with a lower voltage / frequency.

Non-regenerative braking should be a requirement also. If the bus voltage gets too high due to pushing too much power back, the bus needs to get rid of this energy - fast. Most commonly, a DC chopper across the bus, consisting of a switching device and a power resistor, shunt power out of the bus throught the resistor. This may have the side effect of drain the battery too since they're on the same bus. More elaborate switching arrangements can be dreamed up.


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## daveinsingapore (Jul 17, 2008)

samborambo said:


> OK, I haven't had a chance to flick back the last few pages and catch up but I'm assume we're running with the BLDC idea and ditching Induction.
> 
> hey Samborambo...hows life in the BOP....I miss home...still have family in TePuke and a holiday section at Papamoa...gotta get back there this christmas to enjoy the madness of New Years Eve at the Mount...lol
> 
> ...


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## samborambo (Aug 27, 2008)

Judebert, a good starting point for a torque motor model is the Etel torque motor series. They've got excellent data available online and it's in the right size / torque range that we'd need for a torque motor.

http://www.etel.ch/torque_motors

The bus voltage is a bit higher (600V to 750V DC) but that could be, for instance, halved and the current doubled for a different winding configuration. Just change Kv and Kt accordingly. Other values like resistance, inductance, etc will also have to change. Give me a yell if you need some help checking / converting parameters.

Obviously, these are inrunner motors that may not suit our mechanical criteria. I think it would be easier with an outrunner having the rotor attached to the rim and the stator attached over the brake calipers. For the sake of the drive electronics, there shouldn't be any difference.

Sam.


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## samborambo (Aug 27, 2008)

Guys, I was reading back through some of the posts about the specific power (power to weight ratio) of an electric motor. Let me clarify things a bit. Electric motors are torque machines. That is, they can produce constant torque up to their rated speed. Roughly, the size of the machine is proportional to the torque required. Since power (in Watts) is the product of torque (Nm) and rotational speed (rads/s), they exhibit low power at low speed and vice versa for a given torque. The rotational speed of a motor is limited by the bearings, BEMF, core iron losses and the load. A 15kW motor that fits in the palm of your hand is very possible, however, the power isn't very usable at such a high speed for our application. A reduction drive can be used but the efficiency of the gear box is quantified as a torque (friction) loss and therefore also proportional to speed. So at higher speed, the losses in a reduction drive are a lot higher.

I'd much prefer the losses to be electrical where they can be controlled to a greater extent. Also, with some improvements to the existing torque motor design, we can increase that torque to weight ratio.


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## samborambo (Aug 27, 2008)

daveinsingapore said:


> samborambo said:
> 
> 
> > OK, I haven't had a chance to flick back the last few pages and catch up but I'm assume we're running with the BLDC idea and ditching Induction.
> ...


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## 3dplane (Feb 27, 2008)

I'm glad someone else jumped on board...I started feeling like I'm a BLDC outrunner salesman or something. This is after all a diy hubmotor thread and that is the only kind of motor (outrunner bldc) in my opinion that will be able to pull it off.Both from the aspect of building ease and characteristics.
The thread however split off a little into controller designing, but that's good,we will need it.
Welcome Sam
Barna


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## samborambo (Aug 27, 2008)

3dplane said:


> I'm glad someone else jumped on board...I started feeling like I'm a BLDC outrunner salesman or something. This is after all a diy hubmotor thread and that is the only kind of motor (outrunner bldc) in my opinion that will be able to pull it off.Both from the aspect of building ease and characteristics.
> The thread however split off a little into controller designing, but that's good,we will need it.
> Welcome Sam
> Barna


Cheers Barna. I'm gonna repost some stuff from another thread I posted on yesterday since I think its probably more suitable here:



samborambo said:


> WheelMotor,
> 
> The concept of a hub motor with the rotor fixed to or part of the wheel rim and the stator attached to the caliper assembly is something I've been toying with for the past month or so.
> 
> ...


and...



samborambo said:


> MOSFETs wouldn't really be suitable for a high voltage (~300V) design because of the ohmic losses. Drive systems in this power range almost exclusively use IGBTs due to the lower losses. IGBTs' losses (volt drop) are proportional to current whereas MOSFETs' losses (ohmic) are proportional to the current squared. You can get suitable MOSFETs in that power range but they won't perform as well. The drawback with IGBTs is more complex transistor driver circuit (require negative bias for efficient turn-off).
> 
> These IGBT six packs are specifically designed for hybrids and would suit individual wheel motors:
> 
> ...


Questions / comments welcome.


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## 3dplane (Feb 27, 2008)

About switching motor configuration:
Unfortunately it's the number of magnets(poles) that determines the rate of angle the rotor will advance with each next cycle of phases,not the winding. On top of that with a certain winding scheme we are forced to use a set number of magnets. Usually there is about two different magnet pole combos that will work well with a set winding scheme. 
The only simple way I know of changing Kv with a set (built)motor is maybe make a star(wye) - delta switch. There should be roughly X1.7 difference in Kv. I saw a video where they made the stator ona slide so it could slip in and out of the rotor to change Kv , but thats a little involved.
I'm sure there is a bunch of solutions but the complexity has to be considered. Barna


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## samborambo (Aug 27, 2008)

3dplane said:


> About switching motor configuration:
> Unfortunately it's the number of magnets(poles) that determines the rate of angle the rotor will advance with each next cycle of phases,not the winding. On top of that with a certain winding scheme we are forced to use a set number of magnets. Usually there is about two different magnet pole combos that will work well with a set winding scheme.
> The only simple way I know of changing Kv with a set (built)motor is maybe make a star(wye) - delta switch. There should be roughly X1.7 difference in Kv. I saw a video where they made the stator ona slide so it could slip in and out of the rotor to change Kv , but thats a little involved.
> I'm sure there is a bunch of solutions but the complexity has to be considered. Barna


Not changing the phase relationship of the windings, just the parallel/serial connection of those windings within each phase. Think of a 3 phase transformer with multiple secondary windings - they can be hooked up in either parallel or serial to get the desired voltage. Yes, delta/star is an option too - commonly used in induction motor starting to reduce inrush current.


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## 3dplane (Feb 27, 2008)

Sam!
Ok I see now. For just a rushed guess I can imagine some serious amps being drawn in the paralell config. Maybe I could take one of my easy to rewind motors (small) and do some "real world"  testing when I get time.
Although I will have to sit down infront of a piece of paper and stear at it to figure out the bunch of wires I'm gonna end up with(for hookup).
Barna


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## Bugzuki (Jan 15, 2008)

3dplane said:


> View attachment 785
> 
> 
> View attachment 786
> ...


Are those 3 phase motors or single phase? 

Since it appears that everyone would like to see a BLDC motor I am willing to switch to that. Just so I can get started on a new design.

How many stator coils do you want?

How many magnets? 
Can the magnets just be arranged in the formation of your pictures 3dplane? 
Is there a configuration that is better?

What size stator and rotor are you looking for?


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## 3dplane (Feb 27, 2008)

Hey Bugzuki!
Yes those are 3 phase BLDC motors. As enjoyable it is to look at your computer creations I don't know if we are ready for it yet. I keep saying I need to get a F&P stator or complete motor (washing machine) and do the magic to it and see what it does, but nowdays life is crazy. Those come in 36 and 42 arm(finger) versions.(also called smart drive(F&P)). As far as I know they are about 10" dia.(stator) and have no clue on stack thickness.
What the heck.. if you want to go at it, why not a 36 arm with 48 mags.
Not even sure if thats a good combo yet but thats what I would try first.(if I had a 36 arm stator). Magnet coverage ideally is around 80% as I hear,but that might just be from an efficiency stand point.For our purpose we may have to let go of a few % of efficiency in order to make it work and just do what we have to do.( like 100% mag. coverage). As you can see one of the motors have quite a bit of space between magnets. (~75%?) that is a spinny little sucker. The bigger motor has 100% coverage that one has a shockingly low Kv (rpm/volt).Just a few brain babbles. I already ordered a CC HV 110 controller (48V 110 A R/C brushless controller) to put the big one to the test a little bit.
Barna


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Sam!
> Ok I see now. For just a rushed guess I can imagine some serious amps being drawn in the paralell config. Maybe I could take one of my easy to rewind motors (small) and do some "real world"  testing when I get time.
> Although I will have to sit down infront of a piece of paper and stear at it to figure out the bunch of wires I'm gonna end up with(for hookup).
> Barna


'stearing' it in the right direction is what we are after 3D...but if you want to have a good look at it...ie 'stare' at it..then you may want to use a programme like this one to see the characteristics of wire and how much you could use.....

also on the larger hub motor design Samborambo mentioned using aluminium and not copper and from the characteristics of the two displayed in the programme above I can understand why.

take a look at http://wiretron.com/nicrdat.html 
and download their free software called wtsetup.exe

hope this helps...


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## 3dplane (Feb 27, 2008)

Yes,we could also be steering it in the right direction. Would you really like me to program you? "programme" 
On a serious note I would just like to get a basic design down before getting into untested waters with the fancy stuff.
And by basic design I mean actual built.Once we know size,number of poles mag.size,strenght number of arms,wire size,#of turns etc. and we get some performance data,then I feel more comfortable with unknown(to me) things to use.
Barna


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## samborambo (Aug 27, 2008)

daveinsingapore said:


> 'stearing' it in the right direction is what we are after 3D...but if you want to have a good look at it...ie 'stare' at it..then you may want to use a programme like this one to see the characteristics of wire and how much you could use.....
> 
> also on the larger hub motor design Samborambo mentioned using aluminium and not copper and from the characteristics of the two displayed in the programme above I can understand why.
> 
> ...


Dave, it may be the three glasses of wine I've had this evening already but you've lost me mate. Why are we looking at nichrome heating wire? Power dissipation is ohms per meter x I^2 x R x winding length. What's with needing a program to work that out?

Anyhoo...

I like the F&P stator design - at least their later 36 finger revision. It would scale well to a larger (thicker) design without needing to do a FE analysis of the resulting design - just increase the dimensions proportionally. However I don't think there's any steel backing on the stator or the rotor - I'd have to model whether or not it makes a big difference to the flux.

Michael Lawley, of Eco-innovation in NZ, sells "inventor kits" of the F&P motors aimed at wind or micro hydro generation. He's done extensive testing with the whole series of smart drive motors for generation so he may be able to answer a few of your questions. There's a fair bit of performance data available on his website.


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Yes,we could also be steering it in the right direction. Would you really like me to program you? "programme"
> On a serious note I would just like to get a basic design down before getting into untested waters with the fancy stuff.
> And by basic design I mean actual built.Once we know size,number of poles mag.size,strenght number of arms,wire size,#of turns etc. and we get some performance data,then I feel more comfortable with unknown(to me) things to use.
> Barna


yes Barna one small step at a time...there are several DIYers who have built BLDC motors without recording or understanding why it was working. The aim here is to design one from known data...hence my inclusion of the last link to 'wiretron'....and with notes that Samborambo has included concerning the design of the hub motor and controller we should be all heading in the right direction and not just charging ahead like a herd of young steers....lol please do not ask me how the stearing thing began...must have been from your side aye....Barna...


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Hey Bugzuki!
> Yes those are 3 phase BLDC motors. As enjoyable it is to look at your computer creations I don't know if we are ready for it yet. I keep saying I need to get a F&P stator or complete motor (washing machine) and do the magic to it and see what it does, but nowdays life is crazy. Those come in 36 and 42 arm(finger) versions.(also called smart drive(F&P)). As far as I know they are about 10" dia.(stator) and have no clue on stack thickness.
> What the heck.. if you want to go at it, why not a 36 arm with 48 mags.
> Not even sure if thats a good combo yet but thats what I would try first.(if I had a 36 arm stator). Magnet coverage ideally is around 80% as I hear,but that might just be from an efficiency stand point.For our purpose we may have to let go of a few % of efficiency in order to make it work and just do what we have to do.( like 100% mag. coverage). As you can see one of the motors have quite a bit of space between magnets. (~75%?) that is a spinny little sucker. The bigger motor has 100% coverage that one has a shockingly low Kv (rpm/volt).Just a few brain babbles. I already ordered a CC HV 110 controller (48V 110 A R/C brushless controller) to put the big one to the test a little bit.
> Barna


hey I went to reply to this one this morning but could not find the link I was going to use...so here goes ...

Hey Barna ...glad to see you cottoned onto the F&P smartdrive, and for a Kiwi invention those smart drive rotors work well, but most DIY people just use them as they are and never rewind them, I am looking out for a couple of stators off of an F & P myself, and am willing to rewind them to get the results I want, but one step at a time. 

here is information about them http://www.sustainability.ofm.uwa.edu.au/__data/page/142649/FPall.pdf

as you will see not many guys actually unwind the stators and use them any differently, I do not see why we can't get a match pair of them, as long as they have the same number of 'fingers' and bond these stators to geather and then rewind them with what ever wire we want and with what ever count of windings untill we have the stator ready for what ever. As for the outer drum...why not look at a brake drum off of a decent sized older car or small truck. I am looking for dead F&P's here in Singapore but doubt I will find any, mean while I am working on a smaller easier project, using the stator off a motor cycle and powering up a smaller hub for a run about scooter...more on that later...

hey Samborambo....yeah the heat is still hot as here in Singapore, hitting 34-35 again after a few months of the 30-31 degrees, and if you were last here when you were 5 years old...I doubt if you would recognize the place...I have been here 3 years and I have seen it change since 2005...

ciao for now...

hey Barna have fun reading the PDF about F&P motors...


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## samborambo (Aug 27, 2008)

Oh, forgot to mention, Eco-innovation does an after market pressed steel rotor drum for the smart drive motor. Add some neodymium magnets to the steel rotor and you've got some more transient power to play with.


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## daveinsingapore (Jul 17, 2008)

> Dave, it may be the three glasses of wine I've had this evening already but you've lost me mate. Why are we looking at nichrome heating wire? Power dissipation is ohms per meter x I^2 x R x winding length. What's with needing a program to work that out?
> 
> 
> > hey barna perhaps I should give you this link too...it is actually the magnetic wire you should be use not the nichrome heating wire mate..we are gonna build a motor ....not a heater to keep your tootsies warm in the winter...lol
> ...


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## samborambo (Aug 27, 2008)

Oops, didn't see the magnet wire there. I was actually looking for nichrome the other week for another project but there's a pretty limited selection from NZ suppliers.


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## samborambo (Aug 27, 2008)

This guy has almost got the right idea:

http://myownhybrid.wordpress.com/2007/12/10/motor-design/

Except he's designing a single sided axial flux motor. The torque is close to what you'd want from a hub motor in a car but, as he states, there's big problems with the axial forces (8000N!). I take my hat off to him learning LUA scripting in FEMM. I've been using it for a couple of weeks and still trying to get my head around the software!

A double sided axial motor (rotor magnets at both ends of the stator) would be appropriate from the motor performance point of view but then trying to fit that into the wheel would be very challenging. I'm keen on designing a double sided axial motor for a motorbike conversion (not a hub motor). Around 13kW rated and 40kW peak on a 6:1 ratio chain drive.

His design has peak power of 16kW at 50km/h per wheel (32kW at 100km/h, etc). Don't know what the max power would be since it depends on the stator thermal design.

Handy formula for calculating power from torque:

P = T r v / 1.8 d

P = power (W)
T = torque (Nm)
r = gear ratio (1 for hub motor. eg: 5 for 5:1 reduction box)
v = road speed in km/h
d = wheel diameter


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## daveinsingapore (Jul 17, 2008)

samborambo said:


> This guy has almost got the right idea:
> 
> http://myownhybrid.wordpress.com/2007/12/10/motor-design/
> 
> ...


Yeah Samborambo that guy....Vasco surely had an impressive project under way...and if are using FEMM too..we should have a few more answers before too long. I am interested in the electromagnetic simulator he was using, where in we can input different physical characteristics and get what we get...am waiting for a response from Vasco....or do you know where that simulator comes from...

have a great day in the Bay mate....Singapore is getting ready for the first race of Formula 1 under lights at night....almost as good as Bay Park under lights....but with more office blocks and hotels around....yeah Singapore is buzzing this weekend....would not mind seeing a electric car enter the Formula 1 races in years to come...pit stops would have to be really quick..to recharge our batteries, or perhaps to change them...lol

well dreams are free.....ciao for now...


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## 3dplane (Feb 27, 2008)

Hey Dave!

People don't rewind the F&P because they use it as a generator.
For our purpose we have to give it a "little"more current handling capability with thicker wire (or more strands in paralell) for one,and a "special" winding pattern have to be used (depending on details) so that the controller knows what to do. And the motor actually works.( here is where a little understanding plays part). It would be weird to have to set the car to "spin cycle" to go forward and quit jerking back and forth  As a matter of fact I'm yet to see anybody that made a high power motor out of F&P,all I've found is alternators. Btw the site is cool.

Sam!
The dual rotor axial flux design works pretty good in homemade wind mills, but as you stated in your last paragraph a few posts above,the "thermal design" is a big challenge. The coils have to be encased in non conductive material to keep eddy currents out (I know you know this) and therefore heat dissapation is almost non existent. The guys at otherpower.com been making big machines like that and judging from the size of those and output in KW I'm not sure how it would perform as a motor. On the other hand I think mars has an axial flux bldc motor but its small (for a car) and I have no user feedback on any.(claims are one thing) Oh yeah don't drink too much wine...leave some for me too
Barna


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Hey Dave!
> 
> People don't rewind the F&P because they use it as a generator.
> For our purpose we have to give it a "little"more current handling capability with thicker wire (or more strands in paralell) for one,and a "special" winding pattern have to be used (depending on details) so that the controller knows what to do. And the motor actually works.( here is where a little understanding plays part). It would be weird to have to set the car to "spin cycle" to go forward and quit jerking back and forth  As a matter of fact I'm yet to see anybody that made a high power motor out of F&P,all I've found is alternators. Btw the site is cool.
> ...


Hey Barna the reason why guys do not unwind the stator of an F&P and rewind is cause they do not want to...and they do not need to...
well this is where I come from a different stand point...

I actually 'want' to unwind the existing 2380 turns of .8 wire off of the 42 fingers of the stator and after some calculations will use either a heavier guage wire and rewire the stator using either the LRK opposite pole variation or what ever else works and will do so untill I get something that actually works as a torquey motor. (I spent 6 years in the electronics industry as a younger man, including transformer winding and circuit board production, assembly and development) so winding a few hundred meters of wire is not going to stop me....unlike the DIY guys who want cheap generators, I am not just going to use what is there, yes I under stand the principles we are dealing with here, fewer turns give us more torque at less RPMs, and heavier wire gives us current carrying capacity...so heavy wire, not too many turns and good voltage and neo magnets will give us what we want..right...

under stand this, I am using the stator of the F&P cause it is there already and measures 250mm in dia....the rotor I can use or change at will, no worries there...I am not....I repeat I am not going to use the F&P washing machine controller....so there will not be any wash, rinse and spin cycles ok....there are other controllers out there already suitable or adaptable for my needs....and I will look at new developments as well...

I am also looking for stators of different sizes for different projects, but the principles I use from one project I will transfer to the next...I actually have three projects in mind.....will tell more later...nuf said....


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## 3dplane (Feb 27, 2008)

Hey Dave!
Yes Sir! That's the point: get the system down on a smaller scale and adapt the experience later.
For example for that 24 arm large motor I could not find a winding pattern for my number of poles,(even if you can, the aAbBcC stuff gets pretty confusing when dealing with that many arms(legs,fingers,teeth)),so I test wound on a lot smaller 24 arm stator I had,fitted with the same #of poles,and the third pattern I liked,so that's what the big one got.
I'm jelous you got an F&P to play with.
Not to be picky just a little correction on # of turns: the less turns(wraps),the "hotter" the motor.Meaning higher Kv. Tries to turn faster.
The more turns, it will be slower. Remember the motor while spinning as a motor it's also acting like a generator. The more turns it has the more voltage is generated to fight the supply voltage(slower) ,The less turns it has the faster it wants to go because it takes more rpms to start "leveling" out that supply voltage. 
But there will be dramatic changes with these numbers when size goes up or even just stator lenght changes.
Why dont you PM me with your project(s) as i'm curious but don't want to clutter this thread.
Barna


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## daveinsingapore (Jul 17, 2008)

3dplane said:


> Hey Dave!
> Yes Sir! That's the point: get the system down on a smaller scale and adapt the experience later.
> For example for that 24 arm large motor I could not find a winding pattern for my number of poles,(even if you can, the aAbBcC stuff gets pretty confusing when dealing with that many arms(legs,fingers,teeth)),so I test wound on a lot smaller 24 arm stator I had,fitted with the same #of poles,and the third pattern I liked,so that's what the big one got.
> I'm jelous you got an F&P to play with.
> ...


 
I understand what you are saying and yes I am not going to going straight into the F&P rotor yet, I have a few other things on the work bench to clear first, but mean while I will work on the principles...like the winding sequence on scratch paper and figure out what can be done, I also am awaiting a simulation programme that hopefully will answer a few more questions quicker. I am going to be working on a smaller rotor first...so do not Barna....You may get a F&P rotor before I start stripping my one...
and I am going to still look for more of these rotors here in Singapore, all to geather I want to have a minimum of 5 or maybe 10 on hand depending on how well the project I have in mind goes...

ciao for now...and as for the # of turns....yeah I got that bit backwards...I was typing here while holding conversation across the office...and looking at my notes at the same time....yeah less turns give us higher RPM per volt and higher current draw, while more turns gives us fewer RPM per volt and lower current draw, any way I was trying to talk about it so guys out there could understand and I did not mention "Kv's" at all only cause some guys here have never worked with on a "RC Heli with a ESC and BLDC responding to Kv's because of the number of A123's they had on hand"...I was trying to not get people tooo confused toooo early ok...just wanted to make a point that we can change the characteristics of a EV rotor by rewinding it...ok..


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## samborambo (Aug 27, 2008)

Dave, we've got some parallel conversation going on between here and the "In Wheel Motor ... Affordable" thread. 

You're trying to hunt down FEMM? Type FEMM into google - first hit. Didn't look hard, did you? 

Have a good read through that Portuguese blog on FEMM design - there's obviously some good work to draw upon there.

I'm gonna check out the FEMM hub motor svn repo tomorrow if I have time.


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## daveinsingapore (Jul 17, 2008)

samborambo said:


> Dave, we've got some parallel conversation going on between here and the "In Wheel Motor ... Affordable" thread.
> 
> You're trying to hunt down FEMM? Type FEMM into google - first hit. Didn't look hard, did you?
> 
> ...


haha you got me there....I was not asking for the FEMM...I downloaded that before I asked for a former programme he had been using and he emailed me back saying he would arrange to get it to me...the FEMM is fantastic and so graphic....so attractive to all you magnetic types out there...and a bit past me....but I have it and will go thru it once I have more data to use with it.


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## max2tall (Sep 22, 2008)

Hi Gentlemen & my 2 cents worth,

Interesting conversation this one- but I was wondering if you are all really really sure a hub motor is the best arrangement for a road vehicle, in which you want to reduce unsprung weight, not increase it.

You can still go for wheel motors, but mount them inboard (near the batteries & controller, nice & protected from kerbs & puddles also) with a simple driveshaft out to the wheel.

Cars want different very handling characteristics to forklifts where hubmotors are good. One of the first thing we do to improve handling & performance is change to lightweight wheels.

I was drawn to this thread whist doing my own searches on motor design for a non EV application, which requires a motor simply to provide smooth torque opposing the direction it will be physically driven in, cogging and back emf being my issues, except back emf will aid my driving current but I need to control it. Will post separately on that one, and appreciate anyone's input 

BTW, Hi Dave - I'm also in Singapore since 2005, ex Sandgroper via Brunei of all places! I'll be glad when the F1 nonsense is out the way huh 



Cheers, Max


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## daveinsingapore (Jul 17, 2008)

max2tall said:


> Hi Gentlemen & my 2 cents worth,
> 
> Interesting conversation this one- but I was wondering if you are all really really sure a hub motor is the best arrangement for a road vehicle, in which you want to reduce unsprung weight, not increase it.
> 
> ...


 
Hi Max..welcome to the forum.....now was that 2 cents with or without GST...you know how 'kiasu' the locals are here...

Any way about this design forum, if you read back thru listings you will see that the sprung weight story has been banged about quite a bit, and has been set aside so that this group can just design and build without the worries of high speed performance and all that that conjures up...so please do not be dismayed to read that we are continuing along this route...

as for you being in Singapore...yeah we can at least watch the delayed broadcast of the F1 at 10 oclock without having to pay for the pleasure of sitting out there in the heat...lol

I have included one the all inspiring pictures of what EV fans a dreaming of...
ciao for now...gotta go watch the box...F1 is on....


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## 3dplane (Feb 27, 2008)

*Re: miniature "hubmotor" testing*

Hi!
I finally got a 48V 110A bldc (rc) controller,so I decided to put my large homemade outrunner to the test.
This weekend I also didn't have to work so I had time to rig this motor up to a gokart that I made years ago for my daughter.
To be fair to the hubmotor theme it is hooked up with no gear reduction.
The motor's outer(rotating) surface drives a belt wich drives a same diameter pulley mounted on the wheel. Very draggy do to the side of the belt is rubbing on the tire,(see pic) and the wheels have those garbage stamped bearings that wheelbarrows use,and the inner V-belt pulley that is just used as a guide to keep the flat belt on track also rubbing on the collet that stops the wheel from sliding on the shaft. (see picture)
Results: The gokart would take off with me and on a slight steady downhill I would have to throttle down due to scary vibrations at around maybe 20mph. After turning around at the bottom I went full throttle to tackle the hill (see pic of the hill) and had my inductive amp meter hooked up wich was pretty steady at around 40 amps untill the belt started brakig loose but I had an "on the fly" tightening mechanism (the vertical piece that the motor is mounted to swings forward and back. Thats what that rope is )so carried on up the hill slowing to around 10 mph at that point.
The total weight was roughly 400 lb. (kart=85, three car batts=~90lb ,Me=222lb ) 
The motor warmed up pretty good, but I could have run 48V instead of 36V in that case the amps would have been 30 instead of 40 giving me the same power.
The motor was also built about two years ago but still I have not found anybody who made one this big and could share information on winding vs performance so I just "winged "it when I built that and actually not bad considering it only has a symbolic amount of copper wound on it.
If I rewind it I will have to run double strands of the same wire I have on it and keep the amount of turns.There is room for it and it needs it. 
It should not get hot at 40 amps.
Barna
Oh yeah! That's me and the EV grin on that last pic


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## daveinsingapore (Jul 17, 2008)

*Re: miniature "hubmotor" testing*



3dplane said:


> Hi!
> I finally got a 48V 110A bldc (rc) controller,so I decided to put my large homemade outrunner to the test.
> This weekend I also didn't have to work so I had time to rig this motor up to a gokart that I made years ago for my daughter.
> To be fair to the hubmotor theme it is hooked up with no gear reduction.
> ...


 
hey Barna congrats big time .......so glad to see that smile on your dial..
you have had fun over the weekend with the bldc motor of yours..and no matter about the belt coming off..at least you have proven the motor dam well works and had power too..

so no we know the motor has power, and if you can recall the number of turns and guage of wire you used, and with measure of the fingers...their width, height and length and the number of neo magnets you used and their size and the diameter of the stator and rotating bell, we can collect that data and postulate...gee isn't that a big word ...lol...the figures...I have a design programme that uses all that data and gives us a power rating with outputs of torque and rpm possibilities depending on voltages used. I take it you used 3x12volt batteries this time.....you mention that at 48v there would be less current...well that is part of the data we can collect..

again congrats Barna...no go and have a beer and enjoy your success..and perhaps fix that belt drive and have another blast later this week...lol

ciao for now...dave


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## 3dplane (Feb 27, 2008)

Thank you Dave!
Yes three 12v (car) batteries. The belt never came off,it just started slipping (and screeching like you hear cars with a loose belt) so I had to yank more tension on it before I slow down too much. The pic just demonstrated the tire and the v-belt pulley (used as washer) pinching the flat belt at a certain spot.
For your calculator:
Stator: 125mm x 20mm (dia x length)
Lenght of arms: 19mm (winding space before hammerhead)
21mm (total length)
Width of arms: 8mm (where the winding goes)
"Depth" of arms: 20mm (same as stator stack thickness in the axial direction see above)

Magnets: 32 pole 6mm(thick) x 13mm (wide) x 26mm(long in the axial dir.) Originally 6mm x 40mm x 26mm but I made three magnets out of one by scoring them and snapping them on the 40mm plane.

Wire: 18 AWG (1.02mm) 
14 turns (delta)
I didn't get a chance to measure the rotor yet but we could guess for now.
Thanks Barna


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## buzzforb (Aug 16, 2008)

i have no idea i fthis has been talked about on this thread, but i though someone may be interested in this article, especially considering you guys are looking at building something fomr the ground up.

http://www.thenews.com.pk/print1.asp?id=135239

Finding a source for enameled wire will probably be the hickup.


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## mdlang (Oct 12, 2008)

This is an interesting thread. 

If I may I'd first like to say that I am the production coordinator at a machine shop that produces singular parts and assemblies for a dozen different oilfield servicing companies from both castings and raw material. I do working drawings in Acad. I procure materials, produce manufacturing plans and can program, setup and run quite well cnc mills and not so well the lathes. I also operate manual mill and lathe. 

In short I think I have some experience in the manufacturing sector. 

For about a year now I have been kicking around an idea for a hub motor. I've read through the posts here and there are a few others who have come to the same conclusion as I have.

Along the lines of the kiss principal, retaining as much of the cars original equipment as possible makes the most sense. I will post a screenshot of the Acad drawing I did a while ago to better visualize the concept.

I think the idea of using an oversize rim fitted with the stator and rotor between the rim and the brake disk is by far the simplest. A radial flux design like the F&P best fits this idea. Dual rotor air core axial flux designs like the homebrew windmills are too bulky. They are radially large and axially thin. We need the opposite. 

The unsprung weight issue is a non starter as far as I'm concerned. Every effort should be made to economically reduce the weight but this design according to my rough calculations should add no more than 50-60 lbs per wheel. Besides the results I'm looking for don't really factor excellent handling.

Anyway I'll try to post the drawing I did and also a link to a pdf on radial flux PM alternator design that I'm sure several of you will appreciate .

Mike

http://repository.tudelft.nl/file/80792/161816


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## mdlang (Oct 12, 2008)

BTW, aside from details of the coil/stator sizing and configuration. From an actual manufacturing standpoint, controller and batteries not included, the biggest pain in the butt and likely the single most expensive part to prototype (Ironically also the cheapest to mass produce) will be the manufacture of the laminates for the stator.

Mike


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## Bugzuki (Jan 15, 2008)

Since the plan got changed to a BLDC motor I have been thinking about making the design somewhat like you have posted MDLang.

I am just worried about if the bearing goes bad the weight of the car would be riding on the magnets since there is only about a millimeter of air gap. 

I do not know if automotive hub bearings are high enough quality to maintain that small of an air gap with cornering loads. The bearing might only have a tenth of a mm of twist but if you have a 15 inch rim that twist would be multiplied a lot at the outside of the where the magnets are and could cause the magnet to ride on the stator. I would hope this is not the case but it could be an expensive mistake if it is.

I need to get a hub bearing and play around with it and a wheel. And see how much play there is.


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## Bugzuki (Jan 15, 2008)

I just went out and played with my 2005 Scion a little. I could not feel any movement in the hub by hand. But, I can not simulate a corner with 500 - 1000 lbs of force or more. 

I will need to build a jig and put it in my press to see if there is any movement.

Here are some pictures of the Scion setup. To get any more detail I would have to take the brakes apart, so I did not do that tonight. It looks like it is the integrated hub/bearing system.


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## mdlang (Oct 12, 2008)

Hello Bugsuki,

I'm confident an OEM bearing is of sufficient quality to avoid the kind of runout your worried about. I'd also be very very surprised to find out that an alloy rim would deflect much either. If the rims deflected much at all they would certainly stress crack quickly.

I quickly overlayed a couple lines in the hub drawing to see what a .03 bearing movement would do at the stator(.03 I think would represent a well worn bearing that should have been detected and replaced long ago).

Even with some hug deflection the rotor only moves .04 or 1 mm.

I would think the air gap on a motor like this could safely be .08 or so. I realize a smaller air gap is preferred but I know the windgen guys have increase their air gaps with little decrease in performance as a generator. I think a slightly larger airgap would also help this area to self clean before any interference occured.

In the event of a complete bearing failure you'll likely have damaged motor but I would fully expect that and with healthy routine maintenance I'm sure it could be easily avoided.

Your scion looks like the perfect candidate for this kind of design. You already have the oversize rims and plenty of space between the rims and the brake caliper.

Heres the drawing


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## EVMAN (Jul 26, 2007)

So how much would your hub motor/wheel/tire weigh??


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## marginal (Oct 16, 2008)

Hi Guys,

I've been reading this forum with great interest, as it was something I was particularly interested in a few years back. Like yourselves, I came to the conclusion that a BLDC motor was the way to go. I found the model flyers web pages to be very helpful regarding building simple 3 phase motors from CD drive motors. The ESC's for these motors were still in their infancy and quite expensive. More recently, affordable, powerful ESC have come on the market and prompted me to build motors from motorcycle alternators to use on my kids go-carts.

this is not why I've bothered to register and post on this forum. (I've worked with computers on a daily basis for the last 25 years, so obviously I'm reluctant to sign up for yet another account.)

In all of the post regarding torque and gearing the same assumption holds. That the motor is to use a 3 phase winding and controller. Few seems to have considered the huge benefits in winding for many more phases, leaving the controller to decide the optimum phase configuration for a particular speed and load. 

3 phase is the minimum number required for a functioning BLDC motor. Higher phase numbers would require a slightly more complex controller and is not necessary for most tasks. 3 phase can be mimicked by a controller with enough smarts and a multiple of 3 inividual windings, by sending pulses to one or more winding at the same time. whats more, since the phase pattern is electronically controlled, it can be changed with the driving speed and load, skipping or grouping winding where and when ever necessary

That's the basic jist and a principal that I believed it is used in some of the more sophisticated wheel motors available (or promised) today (eg. PML). An efficient motor design is beyond me, having read some of the technical papers available where the author has gone to great length modelling stresses, flux and stator shapes. I just don't have the patience for that sort of detail. I have in the past much preferred having a go and living with the inefficiencies. 

Good luck with your efforts.


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## daveinsingapore (Jul 17, 2008)

mdlang said:


> Hello Bugsuki,
> 
> I'm confident an OEM bearing is of sufficient quality to avoid the kind of runout your worried about. I'd also be very very surprised to find out that an alloy rim would deflect much either. If the rims deflected much at all they would certainly stress crack quickly.
> 
> ...


 
hi guys...I thought I replied to this one this morning, but upon signing back in this evening..nothing is here..any way here's my two cents worth..

I am all for Hub motors, and if you want to keep as much original gear....brakes and steering as possible, fair enough...I like BLDC motors, with their nice strong magnets and all..but figure this...imagine in 6 months time when your car owner with his BLDC hub motors gets a flat tire....imagine him there on the side of the road struggling to get that darn wheel off of the stub axle....and with all his effort he might pry it off.....if he is hercules....not to mention all those grippy strong magnets fixed with super glue to the inside of his alloy wheel rim....imagine all the metalic rubbish they are going to attract as the car spins around town.
Now how about encasing those magnets and the stator in a housing that keeps all that rubbish out of the way and have the wheel just bolt over the assembly without all fear of things coming apart.....

there are a few tried and tested designs out there already for the 'bolt on' design...all we have to do is do the same thing again...

here is an article with a few pix...they were made by a electric train manufacturer in japan....of all places....and not in china.......(no melamine was used in the manufacture of these babies...)...

have a think about it guys and lets see what happens....

http://www.megawattmotorworks.com/display.asp?dismode=article&artid=172


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## mdlang (Oct 12, 2008)

I'm game, drawing the rim is a pain in the a$$ anyway.

Mike


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## Action Jackson (Oct 16, 2008)

3dplane said:


> Thank you Dave!
> Yes three 12v (car) batteries. The belt never came off,it just started slipping (and screeching like you hear cars with a loose belt) so I had to yank more tension on it before I slow down too much. The pic just demonstrated the tire and the v-belt pulley (used as washer) pinching the flat belt at a certain spot.
> For your calculator:
> Stator: 125mm x 20mm (dia x length)
> ...


 
Hey Barna! Thanks for posting your pics and specs of your motor. Very impressive! I just started researching BLDC motors so please forgive my lack of knowlege in this area. I just have a few questions..

How many teeth does the stator have? I see you used 32 magnets. What grade are the magnets.. N42 or stronger? How did you wind it? Did you do any DLRK or just ABC winding? Any idea how many horsepower this thing has roughly?

If you were to double the size of your outrunner to lets say 375mm diam. how many teeth would you go with on the stator? How did you build the stator? Did you machine all the laminate plates? What brand of controller did you get? Price? Any good companies you would recommend for getting the magnets? Has anyone ordered from K&J Magnetics? http://www.kjmagnetics.com/products.asp?cat=11
Are there companies that sell large stator plates (375mm) or should I plan on having them machined myself?

I'm getting ready to build a large test DLRK outrunner about the same size as yours then hopefully build a larger one if it's successful. I'm dreaming of building a rock crawler E-buggy so this thread has been a great help.

Thanks


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## 3dplane (Feb 27, 2008)

Hi Action!
That motor (stator)has 24 teeth. Magnet grade I have no idea been a long time since i got them but perhaps around N40.It is really not that big of a deal wether its N35 or N42 on experimental level the motor will still work. 
Winding is kind of continuation of DLRK. I had a small 24 teeth floppy drive stator to test windings on before I wound the big one. 
On horsepower: If built properly I'm sure a motor this size could handle 6KW. I was only pushing around 2HP worth of electricity into mine and it got pretty warm,but like mentioned earlier could have ran higher voltage and less amps (less heating). Also the whole winding was just a guess from me and now I know wich way to go with rewinding(after test).
The stator came from a ceiling fan. I can not diy stator laminations.
The controller is meant for rc planes it's a Castle Creations Phoenix HV 110. Cost $230.(ordered from tower hobbies).
Magnets: I have used K&J magnetics before till I found magnet4less.com almost half the price.
Stator plates? That is the biggest hold up currently for me to build a monster.
If you want to learn about these bldc motors go tohttp://www.rcgroups.com/electric-motor-design-and-construction-361/? There is a lot of info there. 
Barna


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## Bugzuki (Jan 15, 2008)

daveinsingapore said:


> I am all for Hub motors, and if you want to keep as much original gear....brakes and steering as possible, fair enough...I like BLDC motors, with their nice strong magnets and all..but figure this...imagine in 6 months time when your car owner with his BLDC hub motors gets a flat tire....imagine him there on the side of the road struggling to get that darn wheel off of the stub axle....and with all his effort he might pry it off.....if he is hercules....not to mention all those grippy strong magnets fixed with super glue to the inside of his alloy wheel rim....imagine all the metalic rubbish they are going to attract as the car spins around town.
> Now how about encasing those magnets and the stator in a housing that keeps all that rubbish out of the way and have the wheel just bolt over the assembly without all fear of things coming apart.....
> 
> there are a few tried and tested designs out there already for the 'bolt on' design...all we have to do is do the same thing again...
> ...


I was thinking about the magnets being exposed like that, but have not come up with a solution. Since we have gone back and forth between AC induction and BLDC so many times I forgot about the issue of getting the motor apart especially if part of it is hooked to the wheel. That, is a major issue. Then, if the person got the wheel off the spare would need to have clean magnets already installed.

That megawatt motor you linked to looks like a really good idea on how to get around these issues. It would also help minimize the distance the wheel is spaced outward.

If I ever finish some of the projects I have taking all my time I will put some more thought into it.

Thanks for the ideas.


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## buzzforb (Aug 16, 2008)

Thought you might like to take a look at these motors:

http://www.danahermotion.com/websit...hless_direct_drive_rotary_motors/d_series.php

I recently contacted them about pricing. I know they currently have a popular scooter motor on the market.


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## unclematt (May 11, 2008)

Hi All,
I started this thread origianally, but since then have had to deal with my construction business shutting down and a few other things that took all my time. I apologize for abandoning the thread for so long. I have yet to even read all that has been posted since I stopped, but will do that tonight.

I have a couple of ideas I have been considering, including using silver wire instead of copper for windings, and have also been looking at the Gemini motor design here. This design has PM's at both ends of the coils, using the magnetic field on both sides instead of just one as is traditional. Check out the site and illustrations and then comment.

Again, sorry for the long absence.


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## unclematt (May 11, 2008)

Here is an article about a new manufacturing method for Samarium Cobalt magnets that is going to reduce their cost and increase availability in a big way. When these go on sale we should do a serious analysis of neodymium vs Samarium Cobalt magnets. If their cost comes down as much as is claimed, they might displace neodymium in most electric motors.

LINK


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## unclematt (May 11, 2008)

I see a lot of people viewing the thread lately, but not many posting. Please feel free to contribute to the thread.


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## Action Jackson (Oct 16, 2008)

Yeah I wish this thread got some more posts too...so here goes....

Question. If I were to build a 19" diameter outrunner with around 60-80 poles and lots of turns on the stator how slow could I control the wheel speed of the motor? Do I need to look for a controller that specializes in slow rpm electronics? Or will a castle creations HV be able to control the motor at slow speeds just like any other 3 phase DC controller? In other words can I get a motor to turn at around 10-20 rpm with lots of torque at the slowest controller setting or is the minimum like 50+?

I read as much as I can on LRK wiring but I'm confused a bit by the winding chart over at gobrushless:










If you look at the 20 pole, 15 stator column you will see a normal ABC winding and the electric gearing says 10:1. I guess I'm missing the point about LRK. I was under the impression that LRK was the way to go for electric gearing. The article at gobrushless made it seem like LRK provides this feature but I guess it's just all about the number of poles and magnets only that will get me slower rpm and higher final gearing ratios?? 

The 14 pole/ 12 stator looks like the last LRK winding combo on this chart. I would love to cut down the weight by going with LRK and skipping every other tooth and get the same performance out of the motor. Could I simply multiply this 14 pole / 12 stator LRK scheme by 5 and do a 70 pole / 60 stator motor?

And if LRK was the way to go do I need the extra unused stator teeth? When I cut the stator laminates do I even need to include them? I could save some weight by not including them. Or do they serve some purpose magnetically? That would leave me with 70 pole and 30 teeth with a big gap between teeth.

I have not seen a lot of discussion of what is a good controller to use for a hub motor in a vehicle. I would like to purchase a controller for a prototype wheel but not sure which one to get. Since this is for an offroad application I want to be able to control the speed of each wheel seperately so 4 controllers works out best for me. Suggestions?? Please send me links to some different controllers and what specs you think I need for my 60 tooth motor.

I'm targetting 300rpm max for my vehicle/buggy project. Hub motor approximate size 17-19" diameter.

Any suggestion of wiring size AWG for this type of motor prototype?

Thanks!


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## unclematt (May 11, 2008)

I have been trying to catch up on all the many posts I missed the last several months. All I can say is WHEW! Made my brain sweat! We have had some really talented guys make contributing threads since this all started. The rift between controller vs. motor design became obvious early on, as did AC vs. BLDC. I am only up to page 25 as some of the more technical .pdf's got me sidetracked a little.

I wanted to point out that I forgot to mention that the Samarium Cobalt magnets I posted about a few days ago work in much hgher temps than neodymium magnets. At the gauss levels we would be using, the two are equally powerful, but the Samarium Cobalts can go to elevated temps without losing their magnetic field. If the new manufacturing methods work out, these will soon be available at reasonable cost.


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## unclematt (May 11, 2008)

Hey All,
Check out this site. I saw it on Beyond Tomorrow. It is a company that will allow you to design custom parts with their software and they will make it for you! While in general this isn't new, their pricing STARTS at $150 for setup, and then as little as $1 per parts thereafter! I may be wrong, but won't this streamline the process of fabing up a motor?

LINK


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## DC Braveheart (Oct 12, 2008)

Action Jackson said:


> The 14 pole/ 12 stator looks like the last LRK winding combo on this chart. I would love to cut down the weight by going with LRK and skipping every other tooth and get the same performance out of the motor. Could I simply multiply this 14 pole / 12 stator LRK scheme by 5 and do a 70 pole / 60 stator motor?
> 
> And if LRK was the way to go do I need the extra unused stator teeth? When I cut the stator laminates do I even need to include them? I could save some weight by not including them. Or do they serve some purpose magnetically? That would leave me with 70 pole and 30 teeth with a big gap between teeth.
> 
> ...


I'll caveat this by saying I am only just strarting out on this topic and am absolutely no expert in any shape or form ... my limited experience comes from thinking about the information on BLDC (and in particular LRK windings) here: http://www.southernsoaringclub.org.za/articles.html

If I understand how these motors work, then your ideal of 70/60 pole/tooth ratio will, as you expect, increase the gear ratio for an LRK winding from 7:1 to 35:1.

As for dropping the unused teeth, as far as I can tell they do nothing for you if not actually wound as in a standard LRK winding (although you can wind them if you go DLRK instead) so I'd have thought you could save the weight by dropping the teeth entirely.

As for controller ... well that's my stumbling block too ... I have not been able to find anything on the net other than r/c plane controllers that obviously cannot meet the power requirements for an EV. That got me to thinking about whether you actually need to go brushless for such a motor. I have an idea for a brushed commutator that could be driven from the outboard rotor (geared back at 1:7 for standard LRK) that could then use a standard DC Controller - I'm thinking about prototyping something small to see if it would actually work.

If you find any high power BLDC controllers out there, let me know!


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## blown57bowtie (Nov 20, 2008)

Very educational thanks to all the contributors. The technology for EV's is here! Batteries will continue to get lighter/stronger/cheaper, that will all be good. I believe the wheel motor has most merits for being universally adaptable to meet the majority of transportation needs. I love the Linux approach to sharing something that will be such a positive thing for mankind.

I don't even have a problem with PML Flightlink trying to make a dime, they've been fighting uphill for about twenty years now. I have a feeling their product will price itself out of the majority market anyway. Without infringing on their patents I think some shortcuts can be made by looking at what they have already done, frankly they have done a lot of the groundwork that's being unnecessarily rehashed here.

Magnets will get cheaper at some point in time, for the time being a few hundred dollars worth of NDs should be the 2nd most expensive part behind the machined (ideally one major piece) motor/wheel core. If the factory brakes can be used for backup behind the regen process, better. Let's face it if the first few of these could cost as much as a couple thousand, and worst case be paperweights in the big picture. Things will get substantially cheaper once R&D is over and parts sourced/blueprints copied in some quantities.


We have contributors for practically every aspect of this project and this is wonderful, but overlaps and I think there are too many Chefs in the kitchen. I believe we need to elect a project coordinator to deligate some responsibilities to move forward. Then a treasurer, some donations, and a leap of faith. 



I come from a employment background of running production companies, sales, management. My hobbies include restoring classic cars, building Harley choppers from scratch, modifying trucks to bemore offroad friendly, quads, dirt bikes, street bikes, things with wheels.


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## unclematt (May 11, 2008)

I would love to get things rolling again. My motivation for starting this thread in the first place was after learning the ridiculous price and unavailability of PML's wheel motor. I too think they have already covered ground that some would continue arguing over.

I fear that many who initially joined this thread have now gone away. There were some disagreements about which direction to take, what design to focus on, etc. Some wanted to focus on the controller side, and some the motor side. It was difficult to coordinate due to these differences needing to be settled before the real work could begin in earnest.

I stand ready to assist in any way I can if we can get some people back, or replace them with new talent.


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## Wayneji (Jul 24, 2008)

> blown57bowtie said:
> 
> 
> > I don't even have a problem with PML Flightlink trying to make a dime, they've been fighting uphill for about twenty years now. I have a feeling their product will price itself out of the majority market anyway. Without infringing on their patents I think some shortcuts can be made by looking at what they have already done, frankly they have done a lot of the groundwork that's being unnecessarily rehashed here.
> ...


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## unclematt (May 11, 2008)

Wayneji said:


> > I agree with *blown57bowtie* - Over the last year I have read a lot of the news articles and literature pertaining to PML Flightlink's 'Hi-Pa drive' and have come to the conclusion that this is one of the most evolutionary implementations of a PM Motor/Generator that I have seen. There is a lot that can be learnt about the current state of the art by reading the patent document relating to their wheel motor - Patent # is GB2440251A and can be found at this link http://v3.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=2440251&KC=&FT=E click on Save Full Document at top to download a PDF of this patent (79 pages) - reading through it I feel some of their claims will be challenged as 'Prior Art' - none the less it makes interesting reading.
> 
> 
> Its interesting that they don't have a U.S. patent. If I am wrong, please post the patent number. I just hope PML doesn't adopt the FAILED business models of Raser Technologies or Chorus motors. Someone needs to sell to the public, and NOT just car companies and aerospace.


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## major (Apr 4, 2008)

Wayneji said:


> > Patent # is GB2440251A and can be found at this link http://v3.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=2440251&KC=&FT=E
> 
> 
> Wayne,
> ...


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## unclematt (May 11, 2008)

major said:


> Wayneji said:
> 
> 
> > Wayne,
> ...


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## major (Apr 4, 2008)

unclematt said:


> major, I can email you the patent if you like.


Thanks, uncle, but I went to the UK patent web site and found it. A bit difficult to handle, but read thru it briefly and did print some diagrams. It does not seem to have anything outstanding. And I remain skeptical regarding their power claims. I sure would like to see an independent dyno test of the thing. Until then, it looks like a 10 or 20 kW motor at best, not 120.

And thanks to Wayne for posting it.

Regards,

major


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## unclematt (May 11, 2008)

major said:


> Thanks, uncle, but I went to the UK patent web site and found it. A bit difficult to handle, but read thru it briefly and did print some diagrams. It does not seem to have anything outstanding. And I remain skeptical regarding their power claims. I sure would like to see an independent dyno test of the thing. Until then, it looks like a 10 or 20 kW motor at best, not 120.
> 
> And thanks to Wayne for posting it.
> 
> ...


Hey Major,
Do you know how many coil subsets there are in each phase of the Hi-pa drive motor at PML?

In the patent there are 3 coils per phase, and they say the Hi-pa drive motor has 24 phases. So its perhaps a 72 coil motor, arranged in 3 coil phases. 

Ater digesting their patent, I think I see a pattern in patents on new motor technology I have read lately: the spreading of total motor currents over a greater number of phases, with the resulting reduction in heat, smaller and cheaper switching means, increased efficiency & power, etc.

Their design of removable motor teeth is also a good idea, but I could swear I have seen it before. Have you seen something like it around? Maybe the difference is the design of the "roots" of their teeth, and nothing more (rounded and aligned with magnetic field lines).


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## major (Apr 4, 2008)

unclematt said:


> Hey Major,
> Do you know how many coil subsets there are in each phase of the Hi-pa drive motor at PML?
> 
> In the patent there are 3 coils per phase, and they say the Hi-pa drive motor has 24 phases. So its perhaps a 72 coil motor, arranged in 3 coil phases.


Hi uncle,

Yeah, from fig 3, it appears 72 stator teeth and 24 transistor bridge plates.



> Ater digesting their patent, I think I see a pattern in patents on new motor technology I have read lately: the spreading of total motor currents over a greater number of phases, with the resulting reduction in heat, smaller and cheaper switching means, increased efficiency & power, etc.


I see a lot of this type of approach. Doesn't make a lot of sense to me. It does not alter the two things needed for torque production, namely flux and current at the air gap. Saturation is limit for flux, regardless of number of teeth or poles or phases. Area for copper and cooling method are limits for current, regardless of number of teeth, poles or phases. As far as switching, total current and frequency determines area of silicon. And with that many poles, they'll have pretty high frequency, even at wheel speed.



> Their design of removable motor teeth is also a good idea, but I could swear I have seen it before. Have you seen something like it around? Maybe the difference is the design of the "roots" of their teeth, and nothing more (rounded and aligned with magnetic field lines)


Just an attempt to reduce cost to assemble. VariableTorqueMotors do it with their motor, but on an outer stator. Honda may have also with the ISA motor. No advantage magnetically, actually adds a slight air gap in there which is undesirable.

Regards,

major


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## blown57bowtie (Nov 20, 2008)

HiPa's power ratings don't seem realistic when evaluating size and weight, I think they're fudging the data: DC motors have the nice feature that you can overdrive them (up to a factor of 10-to-1) for short periods of time. That is, a 20,000-watt motor will accept 100,000 watts for a short period of time and deliver 5 times its rated horsepower. This is great for short bursts of acceleration. The only limitation is heat build-up in the motor. Too much overdriving and the motor heats up to the point where it self-destructs.

Something else that's somewhat relevant:http://www.greencarcongress.com/2008/12/michelin-to-com.html


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## Mike (Jan 4, 2009)

Hello everyone!
I've been reading this thread, and i have also found this page on net:

http://miwamzy.diytrade.com/sdp/453125/4/pd-2504449/3469734-1310123.html

I do not remember if anyone else posted this link if it is so, I am sorry.


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## unclematt (May 11, 2008)

I am still checking to see if its true, but in another wheel motor thread it was reported that PML Flightlink is filing for bankruptcy. I wish these motor innovators would get a clue and understand that they need to actually produce something FOR SALE to the public and not just attempt to depend on "licensing" of their innovations. it is a dead end strategy, and ZERO motor innovators have made any profit by this obviously failed strategy.

Build it for sale to the general public, and they will come...


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## Mike (Jan 4, 2009)

unclematt said:


> I am still checking to see if its true, but in another wheel motor thread it was reported that PML Flightlink is filing for bankruptcy. I wish these motor innovators would get a clue and understand that they need to actually produce something FOR SALE to the public and not just attempt to depend on "licensing" of their innovations. it is a dead end strategy, and ZERO motor innovators have made any profit by this obviously failed strategy.
> 
> Build it for sale to the general public, and they will come...


I do agree with this, but they have to tell in an reasonable price range, not only to big companies whom will bury the whole thing.


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## unclematt (May 11, 2008)

Mike said:


> I do agree with this, but they have to tell in an reasonable price range, not only to big companies whom will bury the whole thing.


I agree. But because these innovators think they are somehow "special" and that their idea is "world changing", they often try to take the easy, lazy way out, and simply advertise what their motor can supposedly do. They don't build demonstrations models for indepedant testing, they don't try to manufacture their motors, and then they expect to make a lot of money. For further proof of this, just take a look at Raser Technology's lack of success with their motor design, and also Chorus's motor (which was coverered on this forum on another thread). It is laughable.


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## Mike (Jan 4, 2009)

Well yes that is true, and I do not understand why they take this lazy way which is an one way trip to bankrupt ...


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## ToyBuilder (Dec 23, 2008)

Raser seems to be doing well with their other area - geothermal. Recently they received funding that can be used for expenses on their executive team growth - they appear to be hiring a motor designer. They may have decided that building their own is worth another look.


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## unclematt (May 11, 2008)

I certainly hope Raser does come to their senses and starts manufacturing motors. However, I would like to see a motor specifically designed for in-wheel use. They have "pancake" motors, but I would like to see them demonstrated in a set up like PML Flightlink did with their electric Mini with motors in all 4 wheels, or even just two.

If it is true that PML Flighlink is going under, I wonder what will happen to The Lightning sports car? Can anyone confirm or deny that PML is on the rocks? With a verifiable source via link?


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## Wayneji (Jul 24, 2008)

PML Filghtlink is indeed in Administration, http://www.pmlflightlink.com/motors/hipa_drive.html (notice at bottom of page) - which is like Chapter 11 in the US. 

They are still trading and have a new website for the Hi-Pa Drive http://www.hipadrive.com - with info on the fully electric Hi-Pa Drive Ford F150 pickup prototype vehicle.


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## Anaerin (Feb 4, 2009)

unclematt said:


> Can anyone confirm or deny that PML is on the rocks? With a verifiable source via link?


I can. It's right on every single page of their website (http://www.pmlflightlink.com/)



Copyright Footer from PMLFlightLink.com said:


> *PML Flightlink Limited - in Administration*
> EM Shires and RW Birchall were appointed as Joint Administrators of PML Flightlink Limited on 28th November 2008 to manage its affairs, business and property. EM Shires and RW Birchall contract as agents of the Company without personal liability. EM Shires and RW Birchall are licensed to act as insolvency practitioners by the Institute of Chartered Accountants in England and Wales.


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## Anaerin (Feb 4, 2009)

Personally, I think the whole "Motor/Controller/Charger" system could be treated as "Black Boxes". That way each could be worked on without having to complicate the other. So, we would have:​

Motor
Controller (For convenience's sake, these two could be packaged into one unit, but for development's sake it is easier to treat them as separate units)
Charger
Generator Controller
As long as we agree on what kind of motor we're using (AC or PM Brushless seem to be the two major options) so the controller can be crafted for it, then all these parts needn't be forced together.

Speaking of the motor, I noticed that PML's description of their system is (or at least was) a "Printed Armature". I'm wondering if this isn't some kind of system where flat coils are PCB-Etched into both sides of a strong but non-conductive material (Or a conductive material covered with an insulator) and stacked with an air gap in-between. So you would end up with something like this (Please excuse the cross-sectional MS Paint illustration):










The blue part would be the armature, and the grey part the stator. The "Flat coils" would be on both sides of both parts.

This is a way to fit a lot of coils in a small space, and should have plenty of torque. Low to medium RPMs (2-5000) shouldn't be a problem either, providing the discs are balanced. If cooling is required, Glycol or something similar could be used, and the gaps (and the rotation) would mean that the unit would act as a Tesla Turbine, pumping it's own coolant around and out to radiators or fins around the outside of the motor.

Let me know what you think.


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## GLEVP (Jul 12, 2008)

Wayneji said:


> PML Filghtlink is indeed in Administration, http://www.pmlflightlink.com/motors/hipa_drive.html (notice at bottom of page) - which is like Chapter 11 in the US.
> 
> They are still trading and have a new website for the Hi-Pa Drive http://www.hipadrive.com - with info on the fully electric Hi-Pa Drive Ford F150 pickup prototype vehicle.



For two years we have contacted PML on a monthly basis to either purchase motors or, in the alternative, a license to manufacture same.

For two years, PML has advised they have contracted with "big players" to manufacture / license their technology.

Guess it hasn't worked out for them.


We wonder when motor manufacturers will begin to understand - nobody cares about "joining a revolution", people want to purchase product.


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## unclematt (May 11, 2008)

GLEVP said:


> For two years we have contacted PML on a monthly basis to either purchase motors or, in the alternative, a license to manufacture same.
> 
> For two years, PML has advised they have contracted with "big players" to manufacture / license their technology.
> 
> ...


I know, its pretty ridiculous that people like PML, Raser Technologies, Chorus Motors, Moller interprises, etc, just don't seem to understand how to make a success out of their technologies. They aren't real businessmen, but they play them on TV...


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## ToyBuilder (Dec 23, 2008)

GLEVP said:


> For two years we have contacted PML on a monthly basis to either purchase motors or, in the alternative, a license to manufacture same.
> 
> For two years, PML has advised they have contracted with "big players" to manufacture / license their technology.
> 
> ...


You probably know this already - Recently I saw a post for a position at Raser Tech where they were in search of a motor designer. The post is no longer there. They also posted a video of their PHEV vehicle that uses a whole lot of batteries - very pricey. They use one of thier motors in the vehicle and a customized generator. They say their SUV will be ready to show off by March. Pacific Power and Light has paid for two of these vehicles.

Such a grand effort for two vehicles. When they finally make money on this it will be when our children can get one on EBay as a relic of the past. 

The only way to make a buck today is just as you said, have a product on the shelf for anyone to buy in any quantity.

Without a motor design developed under our own discressions, we will likely be dependent on what Detroit, Japan, China, and other "big players" move into position. Right now, the big players do not have my vote for innovative positioning.

We need to keep this thread moving or create a new level of effort. Where did we leave off?


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## ToyBuilder (Dec 23, 2008)

Anaerin said:


> ​
> 
> 
> 
> ...


Interesting, this looks a lot like a harddrive design. In a harddrive the greater the ability to read a smaller and smaller space increases the harddrive capacity. I believe drive speeds are roughly 8,000 rpms regardless of their capacity. Originally (20 years ago), jolts and bumps to a harddrive would cause damage as the disks would be rammed by the head or discs would become misaligned/warped. Today damage is far less a problem, but the size of harddrive disks has not changed much. What did they change to make a longer lasting disk array? Also, I wonder if we placed a lot of small disks in a tall pancake stack what kind of torque would be achieved as compared to the wide and short one you have illustrated.


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## GLEVP (Jul 12, 2008)

ToyBuilder said:


> ...
> The only way to make a buck today is just as you said, have a product on the shelf for anyone to buy in any quantity.
> ...
> We need to keep this thread moving or create a new level of effort. Where did we leave off?


I most humbly make a suggestion? If it is taken wrong, I apologize and will back off.

1. As cliched as this sounds - don't re-invent the wheel.
2. Concentrate on the motor. Controllers are off-the-shelf items
3. Use existing technology / off-the-shelf parts only.

Here - you can have one done in a month -
Get a 15kw AC servo motor w/ controller. Remove motor face & machine new face to hold mounting area as well as to accept this -
http://info.rockauto.com/BCA/Detail2img.html?NATHF_513194_fro.jpg&NATHF_513194_BAC.jpg

You now have a powerful, proven motor, with an off the shelf bearing assembly holding lateral & side loads. Slap on a rotor for redundant/emergency brake operation. You are done.


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## Anaerin (Feb 4, 2009)

ToyBuilder said:


> Interesting, this looks a lot like a harddrive design. In a harddrive the greater the ability to read a smaller and smaller space increases the harddrive capacity. I believe drive speeds are roughly 8,000 rpms regardless of their capacity. Originally (20 years ago), jolts and bumps to a harddrive would cause damage as the disks would be rammed by the head or discs would become misaligned/warped. Today damage is far less a problem, but the size of harddrive disks has not changed much. What did they change to make a longer lasting disk array? Also, I wonder if we placed a lot of small disks in a tall pancake stack what kind of torque would be achieved as compared to the wide and short one you have illustrated.


The reason I went for the "Wide and short" is to make the most use of the space available. The size I envisioned that array was taking up the full width of the tire, and having the rim and tire a few mm further out. I also figured the wider the plates, the more torque you could get from the edges.

I know that hard-drives are a lot more resilient to jars and knocks these days, and I believe that is because of the more intelligent use of fluid bearings (for flex) and head parking, with accelerometers to detect falling conditions and parking the heads in a "safe" area before a collision.


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## coulombKid (Jan 10, 2009)

John said:


> This could be very cool. Independent torque controlled high powered all wheel drive and extreme mechanical simplicity. It could be a huge leap forward in terms of vehicle dynamics. It could do full regen with proper brake bias not just fore and aft but also left and right if braking while cornering. It could do active yaw control with the drive assisting the turning of the vehicle possibly even using a combination of regenerative braking and drive on the inside and outside wheels to aid vehicle turning. The computer could dial down the torque to any wheel when excessive slip is detected. All manner of new things could be done that aren't currently possible with today’s cars. It could put the electric car firmly out in front in terms of drivability and nimbleness and surefooted safety.


This track, if taken, would all but eliminate the need for power steering.


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## ToyBuilder (Dec 23, 2008)

While this is a great mechanical advancement, it is both exciting and frightening to a number of industries. For one, no policies that focus on steering and braking equipment exist that will allow legal entities to work with future accident victims. In the beginning, insurance companies will not care, but that may change based on complaints in the courts. If a supplier wants to sew discord, they can begin marketing the incompatibilities or safety of such mechanical changes - salesman can purport much of what they want and its the markets responsibility to make responsible comparisons. Hence, we will see a hording of marketers making $$ on quality and effectiveness campains as these systems begin to proliferate. I love a great idea, but the groups that implement this one will likely need to consider the present pricing and costs of the idea on long-term income and cost structures. One more thing, the US manufacturers have "friends" in the supply business that have existed for more than 50 years. To implement these technologies new suppliers may be required and retooling of significant factory equipment and floor space just to get the idea implemented in a few cars. 

What is needed is a new auto industry - EV and hybrid focused. If a consorsium between existing EV manufactures could be formed that would bring in research and development funding, larger investment interest, EV marketing, ... too much for us in a tiny forum to handle ... or am I wrong?


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## unclematt (May 11, 2008)

I welcome the information posted about PML's wheel motor "printed armature". I wish someone could elaborate further about this method of manufacturing and design. Does anyone have any close up photos of such armatures? If so, please post. There are a few online, but they are blurry and non-detailed. I would also appreciate someone with experience enlightening the rest of us about the actual fabrication details and processes. Video/diagrams/etc would be great!

Thanks for keeping this thread alive! Keep coming with the ideas and information!


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## Anaerin (Feb 4, 2009)

I think the best reference is PML's own site:

http://www.pmlflightlink.com/news.html



> *Internal Construction*
> 
> The Flat Armature design is essentially an ironless disc with coils punched from sheet copper and formed onto non-magnetic disc insulators. The brushes short across two or more points to create a path through the copper thereby creating a magnetic field which interacts with the permanent magnets to create motion. With no magnetic material present in the armature undesirable ‘cogging’ is completely eliminated, providing smooth operation and continuous torque down to zero RPM, with minimal torque ripple. Torque is proportional to current and not limited by saturation, whilst speed is directly proportional to voltage.


There is also a diagram here:

http://books.google.ca/books?id=u_N...tpj2Dw&sa=X&oi=book_result&resnum=9&ct=result (Scroll up to Page 122 to see it, the Printed Armature is Fig 4.4(c) - The one at the bottom of the page).


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## Grumpy (Mar 1, 2009)

Why is it that no one is discussing the new kelly controller for BLDC motors???

http://www.kellycontroller.com/shop/?mod=product&cat_id=41,26,35&product_id=434

KBL12401H,24-136V,400A,BLDC Controller/With Regen.

Grumpy


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## tonycowan (Mar 3, 2009)

Hi Folks,

Has this conversation moved somewhere else?
I would like to contribute some time and effort to this.
I like the idea of housing the motor on the chassis to reduce the weight of the wheel.

Cheers,
tc.


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## 144VDC (Jan 25, 2009)

Hi Tony,
I haven't been very active on here but I am very interested in a high efficiency, direct drive motor.

I am planning to build a 1000lb. 3wheel (2F1R) EV. Wheel motors would reduce the drive train to a minimum, but would add considerable unsprung weight, that is very detrimental to the handling on a light weight vehicle. To avoid the high unsprung weight and protecting the motor from grit, water, salt, mud and all the other thing on the road, I plan to use inboard motors to drive each front wheel through driveshafts with cv joints.

From my calculations, each motor will need to be about 4kw(5hp) continuous and torque near stall, 140nm (100ft/lb); max speed 900rpm. A motor like the Mars BLDC would work with a 4:1 ratio. But I want to avoid the inefficiency and complication of gearing.

I am now in the process of researching and prototyping a low speed, high torque BLDC motor. I have found some other people doing the same thing. It looks very posible.

I would like to hear your ideas.
Jerry


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## lpite (Mar 6, 2009)

Easier to make a conventional wheel motor with a separate brake rotor for mechanical braking. Or make the rim itself the motor spinning on a fixed hub.


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## Bugzuki (Jan 15, 2008)

GLEVP said:


> IRemove motor face & machine new face to hold mounting area as well as to accept this -
> http://info.rockauto.com/BCA/Detail2img.html?NATHF_513194_fro.jpg&NATHF_513194_BAC.jpg
> 
> You now have a powerful, proven motor, with an off the shelf bearing assembly holding lateral & side loads. Slap on a rotor for redundant/emergency brake operation. You are done.


I agree but it would be better to use a bearing that had an integrated ABS sensor. That way it could be used as a speed/position sensor if needed.


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## Bugzuki (Jan 15, 2008)

I think that it is time (if this thread is going to go anywhere) that we stop talking about how nothing is for sale and wishing something was. We need to get down to getting some actual information on here that has to do with the design of the motor.

It has been clear from the very beginning that most people want a BLDC outrunner motor. The new idea of a disk style motor is neat to think about, but we need to start with something we might be able to find information on. 

I would say for now we need to stick with the BLDC motor. 

Like I have said before. I am not the best at electronics. I would like some specifics I can use to start making up some designs. 

I see a lot of people doing research, but none of the specific needed information ends up back in this thread in a form other then links to the other page or patent.

It would be very helpful if someone could come up with:

Rotor/Stator diameter/thickness = Hp/Torque equation with explainations on how the equation works.
Coils to Magnet equation. (ie. how many coils and how many magnets = number of poles)
Number of turns per coil
Type and size wire to use, maybe even a good source.
Type and size/shape of magnets to use. Good source.
Do we want to have magnets that are removeable, so a press is not needed to disassemble the motor?
What power range do we need to shoot for or want?
Once we actually start getting valuable information in this thread we can start developing a plan. 

Hopefully as this project moves forward other work on a controller can be done parallel. Then, said controller would hopefully be compatible with AC induction and BLDC.


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## unclematt (May 11, 2008)

I personally prefer the PML design with an ironless rotor, but encourage people to build any design they can. I just don't want to discourage those who aren't interested in BLDC motors from contributing. I think we can proceed on mutliple fronts.


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## Action Jackson (Oct 16, 2008)

Has anyone used MotorSolve BLDC to help with their hub motor design? I installed the trial edition but it doesn't support outrunners. You need to purchase a license in order to get those features.

http://www.infolytica.com/en/products/motorsolve/bdc/index.html

The coolest thing about this software is you can use a list of materials for your rotor, magnets, stators, etc and it will show you the results. You can tell it to use a certain type of magnet and it will show you the resulting numbers. Number of windings, etc. I have contacted them about how much they want for a license.

In the meantime I'm wanted to ask a few other questions to the members of this disucssion. I'm building my own hub motor because I cannot find anything out there for my application. All this discussion about unsprung weight is not an issue for me because I'm building this for a slow moving offroad application.

1. Any other software out there to help with the design besides MotorSolve BLDC?
2. What material do I use to insulate each stator plate? 
3. Does anyone know of a company that can machine/lasercut my stator plates once I get my design done? My target hub motor diameter is 18". A company that could apply coating/insulating to the plates as well?

I just want to build a prototype first and if I'm successful I'll move on.

Thanks!


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## GLEVP (Jul 12, 2008)

Well, how's this?

We've worked with eTel of Switzerland with the rotor / stator, we've designed & built the housing & electronics. And yes, it is available, and yes, it has been bench-tested with the following results;

550 NM nominal, 880 NM max
Water cooled
Quad-Bearing design - 15,000lb axial/radial load capable (momentary)
1950 max RPM

We are looking for real-world (read: 3rd party) testing. We already know it lives up to these numbers.


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## Action Jackson (Oct 16, 2008)

Sign me up. I'm very interested in testing any hub motor you may have.

Thanks. I'll send a PM.


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## major (Apr 4, 2008)

GLEVP said:


> Well, how's this?


What is the mass, continuous power output and cost?

Regards,

major


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## GLEVP (Jul 12, 2008)




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## major (Apr 4, 2008)

Thanks GLEVP,

I guess the performance is believable from a 70 kg (150 lb) motor. But that is quite a bit to add to the wheel. And you didn't mention the price. 

Regards,

major


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## esoneson (Sep 1, 2008)

*144VDC*: Have you checked out the motorcycle hub motor being developed (shipping within the next month) by markcycle on endless-sphere.com?

Take a look. At 34 pounds, it might be useful in your application when applied to multiple wheels.

http://www.endless-sphere.com/forums/viewtopic.php?f=10&t=7718

He just put up a website for preliminary information:

http://www.doingitall.net/EnerTrac/index.php

Eric


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## Anaerin (Feb 4, 2009)

Okay, some numbers from that sheet (And a little calculation).

Torque: 405.7 ft-lbs typical, 649.1 ft-lbs peak (And that's per wheel!)

Using a 225/45R14 tire as average mounting (Given that this motor is reported as approx 12" in diameter), then this motor would provide a maximum theoretical speed of 205.13KPH (or 127.46 MPH).

Given that most wheel rims weigh between 6 and 14kg, these motors would be a considerable weight to add to the unsprung weight of the vehicle. However, mounting them inboard with CV joints (Which would also allow the original braking systems to be kept for parking and emergency stopping) would make this a non-issue.

Overall, this looks VERY promising, especially as they seem to have controllers for these motors as well. I would be very interested to see them mounted and working on a regular car. They certainly have enough power to be mounted as the primary drive system on a 2WD car.


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## GLEVP (Jul 12, 2008)

PLEASE don't consider using these inboard with CVJs. PLEASE. 100% of the design is purpose-built hubmotor. To use it as an inboard is like playing the drums by beating on them with a violin; sure you are playing the drums, but you are wasting a perfectly good violin.

With regards to unsprung weight - And this is a personal opinion - It is not a meaningful issue on a road car. There are physics involved with the weight, rotational mass, gyroscopics, etc., and all of the calculations in an argument against it are valid. However, in the real world, it just is not significant.

The drawing submitted is older - the current model being used has integrated hydraulic brakes - small, because they are barely needed to stop, and mostly used for standstill / emergency. Also, something manual must be integrated in case of catastrophic electrical failure.

Yes, the controllers are included & matched.

We have had them on a Daewoo Matiz on the rear wheels, and are beginning road tests with four-wheel integration.

However, and as stated in an earlier post, we need a 3rd party evaluatiuon - we already know what they can do.


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## Duncan (Dec 8, 2008)

Hi GLEVP

"Unsprung weight is not a meaningful issue on a road car"

That is a mouthful - on smoooooth tarmac yes but what about the rest of the roads

Personnally I think this will come with full active suspension, as was used on F1 until the idiots banned it, 

The old live axle cars had about half as much unsprung weight and it did contribute to a bit more discomfort on the road - ok on the track


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## Mike (Jan 4, 2009)

Hi GLEVP

I would like to try the hub motors, I am thinking to convert my old car to electric (an Renault 11) which is FWD, but I want in 4WD, because I am living in mountain area, and we have long winters.

And I think this would be good testing grounds.


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## Tesseract (Sep 27, 2008)

GLEVP said:


> With regards to unsprung weight - And this is a personal opinion - It is not a meaningful issue on a road car. There are physics involved with the weight, rotational mass, gyroscopics, etc., and all of the calculations in an argument against it are valid. However, in the real world, it just is not significant.


There's no room for opinions in Newtonian physics... minimizing the unsprung weight is paramount for maintaining good traction, ride comfort, etc., on a vehicle.

BTW - are you the same "GLEVP" referred to in this thread:

http://www.diyelectriccar.com/forum...ii-greatlands-electric-propulsioni-25920.html


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## GLEVP (Jul 12, 2008)

Tesseract said:


> There's no room for opinions in Newtonian physics... minimizing the unsprung weight is paramount for maintaining good traction, ride comfort, etc., on a vehicle.
> 
> BTW - are you the same "GLEVP" referred to in this thread:
> 
> http://www.diyelectriccar.com/forum...ii-greatlands-electric-propulsioni-25920.html


Yes, physics is fun. Real world experience is always a plus, however.

Yes, same GLEVP. The person complaining on that thread left out a few minor (heavy sarcasm intended) details. You know, little things, like he received his order well before the post in this forum. Small details such as how he advised me beforehand how he was planning on posting here if we didn't supply a refund & let him keep the motor and controller. You know, small tidbits like that....


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## david85 (Nov 12, 2007)

Yeah unsprung weight is important as a consideration, but its not going to make as big a difference as some might think. Might change ride quality, but its all about trade offs. It won't mean the difference between a car thats drivable and one that isn't.

*GLEVP,* may I ask if there are any working examples of your products out there? Seeing a working car or conversion with some of your products could help reduce some skepticism. Although I'd like to see anyway because your product line seems to be very comprehensive.


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## aeroscott (Jan 5, 2008)

David85 , Well put . it my not be the fastest on road or track , but it won't be beat on the watts per mile . In china they run these little scooters ( 1 kw wheel motors ) . If we count them china has more ev's then the rest of the world combined .


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## newinvestor23 (May 7, 2009)

Hey,
I have been looking and thinking of building an EV for a while now and I have done some reading but I do not see much on this type of EV? Even though it would be a bit more difficult to get the 2 wheels with the same power, I think it would be a great car. 
I was wondering if it is possible or if there is an example of a inboard motor (or 2, one on each wheel) with CVJs straight to the wheels? do you need a transmission? 
Thanks


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## Alchemist (Apr 16, 2009)

I'm sure most of you have already seen the videos about the Japanese made Ellica. The Ellica 8 wheeled electric car was debuted a few years back but I wanted to post their In-wheel motor videos:

At the 7:20 mark on this video, they start to discuss and show how the wheel motor windings were manufactured:

http://www.youtube.com/watch?v=5SH9TgBOCHM

The beginning of this video link continues the discussion of the wheel motor and follows with the magnets they use. 
At the 2:30 mark it shows two guys carrying the wheel motor and then showing the wheel motors mounted on the car - very cool:
http://www.youtube.com/watch?v=1xztzY2sYe0&feature=related

Hope this is a postive contribution since I'm still at the basics of learning about EV's. 

Thanks!

Ernie


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## sciautusditio (May 6, 2009)

After reading this entire post and seeing that an DIY hub motor is not yet a reality, I had a thought and would like to share it in hopes that someone could tell me that I am all wet or that it is doable.
The magnets that I envision using is .5" x .5" x 2" w/97lbs pull about $3.00 each http://www.magnet4less.com/product_...d=494&osCsid=15037618888186c77a300f88d1d73a9f

Sorry that I am not better at drawing, but I hope it is good enough and the drawing uploads ok.
Thanks, your feedback is appreciated.


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## Bugzuki (Jan 15, 2008)

sciautusditio, your idea looks interesting to me. Lets see if I understand your idea. The alternating current in the stator coils would cause the magnetic field in the coil to reverse. This would then push and pull on the north and south poles of the magnets.

I don't think you would need the iron bar at the top of the N magnet pole if you had a sideway 'H' shape for the coils. This would allow the magnetic field to flow through the coil then through the magnets.

One concern I have is with the vertical magnets there would be an angular difference between the north and south poles. Is this what you were thinking of when you said the stator cores would be triangular shaped. I was thinking the magnets magnets would have to be but the stators would be easier.

Oh now I see where you were going with the purple parts of the drawing. I think it would be easier to design and build if the pink stator bars just extended almost to the magnets. 

I took a couple paint liberties to the lower section of your picture to show what I was thinking. Of course the air gap needs to be about 1mm between the stator bars and the magnets.


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## sciautusditio (May 6, 2009)

I was looking to extend the N & S poles of the bar magnets with the purple areas. Not sure if it can be done or not. I tried testing a few types of metal and nickel, but they just seem to absorb the field, not steer it. Maybe someone in the know can say if it can be done.

You are thinking as I am about extending the stator. I did a quick sketch of what I think you mean by the sideways H stator and it sounds good. Will it create the split poles?


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## sciautusditio (May 6, 2009)

One concern I have is with the vertical magnets there would be an angular difference between the north and south poles. Is this what you were thinking of when you said the stator cores would be triangular shaped. I was thinking the magnets magnets would have to be but the stators would be easier.

Thinking out loud:
A 10" motor would have a 5" radius, if the bar magnets are 2" long the end of the stator closest to the axil would still be about 3" from the center, giving it about 18" circumference. To be safe on motor size we use just over 2.5" radius or about 16" center circumference, about 28" outside circumference. (24) 0.5" bar magnets would give you 75% center coverage & 42% outside coverage.

Or you could setup 32 magnets in "V" shaped pairs w/ a steel seperator at top, giving you a nice 16 pole with 15 or 18 stator teeth.


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## sciautusditio (May 6, 2009)

Back to page 10 (Thanks John). By utilizing the Halbach effect we can re-direct the poles out to the surface of the flat rotors. This will allow us to stack the front rotor one polar cog off from the rear rotor (S on Front rotor will line up with N on Rear rotor, stator sandwiched in middle) and then we can turn the stator windings sideways and have a upper and lower stator on each stator finger. This will take away the exotic H winding configuration and the motor can still be treated just as any LRC configuration.

I envision a stator hub out of aluminum or something with an upper and lower socket on each finger for the stator windings to drop in. This allows us to prewind the stators then assemble them into the stator hub. We could even cast the stator windings into a carbon fiber layup and include liquid cooling if heat is going to be an issue, (this would increase the size of the axle).


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## Bugzuki (Jan 15, 2008)

I do not really see what putting the magnets in a 'V' shape will do for the system. 

I have been thinking about the side magnets and the 'H' stator. Having the magnets flipped on both sides would allow you to have two coils in the stator - one above the other. The coils could be pointing opposite directions.

I don't know if this would be beneficial or even work properly, but it seems like a way to get more power in a smaller package.


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## sciautusditio (May 6, 2009)

I was looking to get more coverage with the V magnet configuration, but I think you are right and this would not produce an overall gain, unless you filled the gap with another smaller magnet.

The upper and lower coils would be more power in a smaller package. If you wanted you could even bring out all six pairs of wires (two three phase sets) and electronically drop off one set for greater efficiency if the power is not needed.

By using the Halbach configuration there would be less external magnetic leakage and you could run a thinner or non-metal motor shell.


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## brdriver (May 26, 2009)

advice you use BLDC motor control system.it is the best of solution on all driver of EV.you can try know Bangrong rechnology's product,maybe you will find new benefit on enterprise.
tks!
best regards!



JRK5150 said:


> I agree, open source is the best way to go for us all! Designing wheel motors should be fairly straight forward. The real issue is in designing an appropriate controller that can act as a controller as well as keeping all of the motors moving EXACTLY in accordance with the others. I suggest we expand this to an open source wheel motor drive system with emphasis on a safe controller. Since we would be designing a controller from scratch anyway, I feel AC would meet the goals better than DC. With AC we could have a brushless system with regenerative braking, ABS, traction control and it would be more efficient. May I further suggest that we focus on writing the control program first (test it with existing hardware), then focus on building our open source hardware. I think this is a great idea and would like to help out any way I can!
> 
> -John


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## sciautusditio (May 6, 2009)

Posting an updated drawing to the axile flux Halbach pancake motor with 16 magnet poles (X2) and 15 coil windings (X2). Can someone run a simulation on this and let us know what would be the best coil configurations (guage, and # of turns)?


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## Bugzuki (Jan 15, 2008)

I might be able to draw up some plans in Pro/Engineer if you want. That way we could work out the exact design and dimensions of things before someone starts building and rebuilding. Also, we would be building to a design, then if changes are needed it would be much easier to track and document those changes.

I do not really understand how the magnets would be arranged to create the Halbach array. The dounut picture you posted is a flat circular array of magnets. These magnet create an enhanced magnetic field on one side (the side that faces the stator). There would then be a mirror array on the other side of the stator. Right? I take it the arrows are the direction of flux movement? What are the x's and o's for. How would the North and South poles of the magnets be arranged to create the one sided effect?


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## sciautusditio (May 6, 2009)

http://en.wikipedia.org/wiki/Halbach_array

Thanks for making me take a second look at the symbols, I have them in reverse, I'll do a follow up artwork change. But correctly stated the (0)donut shape is North facing the stator and the XXX is South facing the stator.
Sorry for any confusion.

With one rotor side it would be like each H. array making a horse shoe magnet with one pole facing the outter stator and the second pole facing the center stator. We get a double bang from having a miror image PM rotor, offset one magnetic cog, sandwiching the stator.

Bugzuki,
I would love to take you up on the drawing, for my CAD skills are very weak. I am currently trying to learn what I can for the stator coils, but the next step is to go junk yard hopping to see if there are any brake drums or such, prefer aluminum, that may fit the bill for a rotor shell.

I am thinking of using sch 80 steel pipe for the axil and turning it down to create a sholder for the bearings.

No set plan yet for the stator mounting to the axil, but I will need a star hub that can take the motor HP force, and I will mold it into a carbon fiber layup with the coils. I am planning the same layup for the magnets in the shells.

Currently working on getting magnets on order to begin testing H array (this will be a few weeks).


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## sciautusditio (May 6, 2009)

These are the corrected drawings [ X & (o) were reversed in previous sketch ]. Sorry for any confusion, I work pretty late on this stuff sometimes.


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## davidru (Apr 12, 2009)

sciautusditio said:


> These are the corrected drawings [ X & (o) were reversed in previous sketch ]. Sorry for any confusion, I work pretty late on this stuff sometimes.


In a google of ironless halbach motors, I came across this link from rcgroups. http://www.rcgroups.com/forums/showthread.php?t=322902
The arrangement of magnets looks similar to yours, and there are some pretty good images of the stator windings. His motor uses a single row of stator windings, where yours appears to have 2. Also, later in the thread, there is some discussion of a planar stator winding configuration that does not use circular coils at all, kind of just zig-zags around an annular ring. This looks like it would lend itself easily to pcb fab methods. A million years ago, I worked on audio tape machines that used pancake servo motors with pwb windings, so it's not a new idea.

I gather the program used to do the magnetic analysis is an open source package called FEMM. I have a bit of structural FEA experience using Cosmos in Solidworks, but this magnetic stuff has me befuddled. If it's anything like the static fea stuff, it's all about preping the model and defining boundary conditions or the output is junk.

One question, towards the outer diameter of the motor in your cross section, I see a yellow bar with a winding around it, then apparently you have an inner stator winding, shown with a narrower yellow bar. Any significance to the width of this bar? I presume as the pie shaped rotor segments converge towards the center, the windings cover a smaller area as well, but I'm only guessing. Also, is the yellow bar a nonmetalic former or an iron core?


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## sciautusditio (May 6, 2009)

I have limited the PM poles to 16 (X2) per rotor plate and the stators to 15 (X2) for ease of assembly for both the magnets and coils. The larger sizes are easier to work with.

I have great respect for rcgroups forum and have studied many of their designs to get closer to an overall solution. My proposed design is similar to Niels’s except that I am stacking the axial rings and using the Halbach effect in two directions. This extends the magnetic circuit and in effect creates an inner and outer 3-phase motor. This should gain both added torque and efficiency by being able to use both or one motor at a time.

Because I have extended the Halbach array the usable portion of the mm(magnetic moment) is only in the (o) – Axial North and X- Axial South portions. Therefore optimum coils would be round or oval shape to fit above the resulting axial mm. On the outer motor portion the mm would be directed from a (1.25” wide X 0.5” Tall X 0.5” Thick) magnet and the inner motor portion mm would be directed from a (0.75” wide X 0.5” Tall X 0.5” Thick) magnet. So, yes, the outer ring stator coils would be larger than the inner ring stator coils.

I am still hitting the e-books to get an overall grasp of stator design and greatly appreciate any input on the mater.

 Note: For magnet purchase convenience and because they fit I have increased the outer three magnets to 1.25” (0.75” + 0.5”). To fit I will need to drop one of the smaller directional magnets (0.5” X 0.5” X 0.25”). During build I will evaluate each configuration for the optimum design.


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## davidru (Apr 12, 2009)

sciautusditio said:


> I am still hitting the e-books to get an overall grasp of stator design and greatly appreciate any input on the mater.


I'm pretty far out of my comfort zone with mag design, but I have found some interesting info, most of which you have likely seen, but I'll throw it out there for other's benefit. The "Cocconi motor": http://www.cafefoundation.org/v2/pd....cocconi.optimized.electric.drive.systems.pdf
though it's a radial flux machine, it apparently uses no iron in the stator. The downside as I understand it is the ironless stator has much lower inductance than an iron stator coil, so the inverter has to add some back (see pic of control on last page). Yet another wheel motor project that looks quite similar http://www.hybridauto.com.au/2.html and a pic of the stator on the bottom right of this page http://hybridauto.com.au/index.html Interesting, their idea of low unsprung mass is 25kg. The whole wheel, tire, brake, spindle and axle carrier on my mr2 probably don't weigh much more than that. Still, I think if the motor could sneak in around 15-20Kg, it might be manageable.

Something else to be aware of, Mark (Markcycle) over in endless-sphere is working with Crystalyte on a motorcycle hubmotor that is nearly the size needed for a small car http://www.endless-sphere.com/forums/viewtopic.php?f=10&t=7718 This will probably not be as efficient or light as a purpose built, ironless motor, but I may buy one to see what they are capable of.


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## Bugzuki (Jan 15, 2008)

Just to make sure you are aware, carbon fiber conducts electricity. I don't know that it will make a difference. Just need to make sure everything is insulated. 

What is the desired outside diameter of the motor? What about the distance between the two magnet plates? The gap between the rotor plates and the stator is about 1mm, correct?


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## sciautusditio (May 6, 2009)

The coil wires are enameled (insulated), but for added protection we can start the stator layup with fiberglass, then CF for stiffness. By using vacuum infusion for the layup we can make a very strong and lightweight stator.

The hub of the Stator:
I am not sure if I know how to do a CF layup that can attach to the axle, but a single complete layup would be best.
Otherwise, the stator hub will need to be steel or aluminum that can be bolted to the completed stator layup or molded directly into the layup.

Rotor, motor shell:
I have always wanted to mold the magnets into the rotor via CF to assure their survival under road vibrations and impacts. After looking at the links that Davidru provided http://hybridauto.com.au/2.html (looks like they use a central rotor) I see that it is possible to make the complete rotor out of carbon fiber.

The Inside of the rotor shell will need to be 5.5” radius; this provides 0.25” clearance to rotor magnets. Plus 0.5” thick shell, gives us a total outside diameter of 12” or 304.8 mm.

I think this will fit most cars.


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## sciautusditio (May 6, 2009)

*I looked into Printed thin film airgap stator windings:*
I tried to find more information on the printed air-gap motor, non-coil, windings but the technical information was very limited. This seems to also be referred to as a zigzag or film coil windings stator.
eg. Herbert talks about it on this thread at rcgroups.com #6
http://www.rcgroups.com/forums/showthread.php?t=322902
Or
EmBest in South Korea
http://www.drives.co.uk/fullstory.asp?id=1301

Due to lack of technical resources, practical examples, and it maybe a difficult solution for a DIY project, currently I can not further pursue a thin film stator as a solution. However; this may be a promising future stator option.


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## sciautusditio (May 6, 2009)

*Coreless Stator (no iron):*
I am zeroing in on a coreless stator configuration to keep down the weight and eddy currents. I was not sure that they could produce enough torque but after much research I see that it has been done before with world class results (solar car races).

*Coil parameters:*
Currently I am looking at 48 coil turns X 5 coils in series per phase (240 turns per phase) rated up to 100A (amps) per phase. With the outer 3-phase motor and inner 3-phase motor this would be 100A X 6 = 600A. Batteries will be selected for 96 volts, 600A X 96V = 57kW. Sounds like a lot of power and heat generated, but this is just for maximum ratings. I expect the normal run of the motor to be around 20A X 96V = 1920W total. _(Note: I am mostly thinking aloud and would love some motor expert critiquing)_

The coil center will need to be around 1 inch diameter and the axial thickness should be about 0.75” (I think, still researching). The nice thing about a coreless stator is that the coils can overlap each other for a thinner stator disk.

*Technical References:*
A major technical reference that I have been using is _“Axial Flux Permanent Magnet Brushless Machines”_ it is not as complete as I would like in some areas (relating to my configuration) but the best resource that I have yet to find.

Some others:
General Axial Flux (I only started reading)
https://oa.doria.fi/bitstream/handle/10024/29715/isbn9789522144744.pdf
General includes Halbach information
http://repository.tudelft.nl/file/80742/078342
UT-Battelle (pg. 91 has a quick summary on AFPM ironless stator core)
http://www.ornl.gov/~webworks/cppr/y2001/rpt/121559.pdf

If you know of better references please share.


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## Hillbilly (Jun 23, 2009)

I have been looking into this for a long time, I used to have a PDF on a solar race car wheel motor design that ws helpful. I just found this PDF today from the university of Queansland. http://www.itee.uq.edu.au/~aupec/aupec03/papers/114 Greaves full paper.pdf

This site shows a picture of their finished product: http://www.hybridauto.com.au/5.html

I think the best wat to go is to print the windings insted of using actual wire, but wrapping wire is much more friedly to DIY'ers.


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## david85 (Nov 12, 2007)

That wheel motor looks great. Love the carbon fiber case and efficiency ratings are off the chart!

Any word on the availability of this motor?

Welcome to the forum, Hillbilly.


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## Hillbilly (Jun 23, 2009)

I don't know where to get one, and I imagine that someone has purchased the design from the University of Queansland by now.

Thanks for the welcome, this site is a great resource. PML Flightlink said they would sell me one of their Hi-Pa drive motors for 9000 pounds. That is about $15k at the currne exchnge rate. The quote was from over a year ago, when I was working on a prototype.


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## Jimp (May 21, 2009)

You guys seem pretty knowledgeable and confident and I applaud your effort. Could you spare some of your talents to work on a conventional AC induction motor design? Please review the "Lets just make an AC motor" thread that I started. Thanks.


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## reyescast (Oct 16, 2009)

I am new here. But I was looking for the best car saving energy and decided to make a EV hub motor.
I already decided to do a 14" wheel hub DC motor.
I was reading yours and I learn about halback effect. I never heard before. But I wanted to be involved. If anybody that lived in Houston area wanted to join to Would be great.


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## Salty9 (Jul 13, 2009)

Adriaya,

This is probably the wrong forum for what you want. Have you tried Source Forge?

http://sourceforge.net/softwaremap/


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## ehustinx (Dec 23, 2009)

Madmac said:


> I also bought one which is why I am developing a control system. I tried to buy an inverter but all EV companies only want to sell motor and inverter as a package. Unlike the industrial market where they are sold separately
> 
> Producing a lighter weight version of such a motor would be a good start.
> 
> Madmac


Hello,

HEC (www.hec-drives.com) is very familiar to the Siemens 1PV51XX motors. Your 1PV5133-4WS20 motor can be operated with a MES-DEA inverter. Please contact HEC for details.

Best regards,

Eddy Hustinx
HEC


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## Arlo (Dec 27, 2009)

Subscribed will read later and do some catching up. Has anyone found anything comercialy availible?


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## IamIan (Mar 29, 2009)

Arlo said:


> Subscribed will read later and do some catching up. Has anyone found anything comercialy availible?


Only if you have a ton of money to through at it... win the lottery recently?

If so then... you've been able to buy them for several years.


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## Arlo (Dec 27, 2009)

IamIan said:


> Only if you have a ton of money to through at it... win the lottery recently?
> 
> If so then... you've been able to buy them for several years.


 Im pretty determined and got my bmx finished other then the making it look pretty part which I am working on right now. Hopefully it shows up on my sig like its suposto. If needed I would build my own.


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## DrLightWind (Oct 8, 2008)

Schmism said:


> I naturally assumed we were thinking rear drive wheels only, as rotating a huge rotational mass creates significant gyroscopic forces when trying to turn. (probably on the order of magnitude that makes it infeasible to use on steering wheels


But I just did a test drive and the hub motor 7.5 kw was installed to the steering wheel 
and worked out fine did't feel any bad side effect. 

DrLW


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## coulombKid (Jan 10, 2009)

DrLightWind said:


> But I just did a test drive and the hub motor 7.5 kw was installed to the steering wheel
> and worked out fine did't feel any bad side effect.
> 
> DrLW


Gyroscopic forces should follow the right hand rule of physics. Steering linkage forces on the rotating mass should impart the resultant forces on the upper and lower ball joints in the lateral directions across the front drive axle assembly. (you shouldn't be able to feel them) The bigger concern is generally a harsh ride due to increased un-sprung weight.


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## Dr. Al (Nov 16, 2010)

Just a few guiding thoughts to share...
1. Hub motors must be *sized for realistic highway performance* that is *equal to or better than ICE power trains*; here are two examples.
A. A *mid sized* ICE powered sedan weighing in at 3000 lbs typically uses a 200hp V6 (min) engine in order to achieve a _13 to 15:1 weight v. HP ratio_. Therefore, *two (for FWD) 70-75kw hub motors are needed*.
B. A *lightweight* 2200lb economy car typically uses uses a 120 Hp (min) ICE drive train to acheive a similar _13 to 15:1 ratio_. Likewise, *two 50-60kw (for FWD) hub motors are needed.*
2. By *concentrating on these two output, 50kw and 75kw, sizes*- many bases are covered. For example, even though small SUVs generally weigh well over 3000lbs, by using four (AWD v. FWD) motors rather than two per conversion- similar or better performance can be achieved AND by using a variable voltage/amperage controller/shifter tremendous vehicle range is possible (more about this in another post).
3. By *limiting the external dimensions of the 75kw hub motors to 14 x 6 inches* (to fit inside an existing 15 inch wheel, say Honda Accord, for example) in diameter and perhaps *limiting the 50kw motor to 12 x 4 inches* in diameter (for economy Civic applications)- you have created an easily adapted format. In fact, the few existing Chinese manufacturers of these motors are sized along this scale.
4. Since we are talking about ease of adaptability to quality used car conversion candidates, again, *Honda suspension- particularly the 1996-2000 Civic independent suspension* would top my list for obvious reasons.
5. Lastly, just as a limited slip differential counts the revolutions mechanically- a *Hall effect (or similar) sensor could measure power imbalances* between two or four motors and similarly make adjustments to the (least complicated but most efficient and durably designed) *BLDC motors*.


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## KenR (Mar 2, 2011)

I agree with JRK 5150 post 43. I don't believe re inventing the wheel. What I thing is needed is to find a supplier willing to deal with the individual or group of individuals. The forming of a CO-OP sort to speak in that way one could obtain the best pricing and materials required. The hub motor I think is the only way to go cuts down on weight, space and a higher out put with less battery usage.
Ken


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## _GonZo_ (Mar 23, 2009)

I made a little research for one of my projects and have find useful info and experiences about in wheel motors, I am going to post some pictures of what I have seen.


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## karlos (Jun 30, 2008)

_GonZo_ said:


> I made a little research for one of my projects and have find useful info and experiences about in wheel motors, I am going to post some pictures of what I have seen.


Great pictures, wouldn't you just love to see some sectional drawings!
Seems they used the original brake shoes?


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## dl_sledding (Mar 17, 2011)

I am not sure if these have been mentioned... and I would like someone who has more knowledge than me to take a look and offer opinions:

http://kellycontroller.com/brushless-hub-motors-c-21_62.html

Thinking that some of the larger ones would work well on a smaller car (say, a VW Rabbit or Dodge Neon or something) for kind of an up-to-40mph city cruiser....

Anyone?

Thanks!


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## KenR (Mar 2, 2011)

First off thanks for putting the link for this site. I have been searching for hub motors and never came across this one.
I am unsure of what you are referring to when you say large ones?
If you look at some of the speed rates 6KW 105 km/ph put 2 on a small car and if you can cary enough batteries you will probably getting more then 40 I suggest you contact them direct for info on what you need> They know their product best and I am sure the would be able to advise you exactly what is required. I know I will be contacting them in regards to converting a Mazda pick up, for hub motors I can't believe the prices.Good luck.


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## High Tension (Apr 29, 2009)

KenR said:


> I agree with JRK 5150 post 43. I don't believe re inventing the wheel. What I thing is needed is to find a supplier willing to deal with the individual or group of individuals. The forming of a CO-OP sort to speak in that way one could obtain the best pricing and materials required. The hub motor I think is the only way to go cuts down on weight, space and a higher out put with less battery usage.
> Ken


Well you can count me in! Like a few of us I contacted PML when they revealed their Mini, now some years ago. I was quoted £20K per wheel. When I regained consciousness the chap said their eventual mass-market target price was around £1K per wheel. That would do nicely... 

I'd guess it's the individual requirements for the wide range of vehicles we'd like to convert would be a problem, especially if we're going for front wheel drive. However, I'd further guess that converting a front wheel drive vehicle to rear wheel hub motor drive would be slightly less of a minefield to whichever company was approached especially where dead axles are concerned...

Ever hopeful.....


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## Gulah (Feb 24, 2010)

Seems like this idea is dead, too bad 

But I still have some questions about hub motors (I've searched the forum but couldn't find answers).

Like for example, if I wanted to place them in the rear axle, I wouldn't need the differential, am I right? Instead it would be the controller's job to make the motors spin at different speeds so that I could curve right? Are the controllers able to do this?

Thanks for your time and sorry for my english


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## High Tension (Apr 29, 2009)

Gulah said:


> Seems like this idea is dead, too bad
> 
> But I still have some questions about hub motors (I've searched the forum but couldn't find answers).
> 
> ...


I'd say far from dead, in fact I'm sure wheel motors are the future. It's a shame they're rather expensive at the moment. But look right through this website to see actual progress: http://www.e-traction.com/

No differential is required, search the forums for 'torque control'.


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## Gulah (Feb 24, 2010)

Yes I've seen that site, but where can i buy them? How much do they cost? If I have 4 motors how many controllers do I need? How much does the controller costs? Is the differential problem solved? So many questions ...


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## High Tension (Apr 29, 2009)

Here's another company that's getting there. 

http://www.alibaba.com/product-gs/419728934/4_10KW_hub_brushless_electric_motor/showimage.html

Up to 10kw. My small Axiam van did fairly well on a single 4KW motor so although earlier in this forum 40kw per wheel was mooted one wonders how even 2 x 10kw would do in a light vehicle? This company say they'll build other sizes and somewhere in there prices are quoted as USD1500.

I would be concerned about quality but that aside, wondered whether, instead of actually replacing the hubs when converting a [front wheel drive] vehicle, why not dump the gearbox, mount a pair of these back to back in place of the gearbox and have new driveshafts made? That way you've not altered the existing brakes [which could be a serious insurance issue in the event of a crash investigation], have no unsprung weight issues and are not relying on what might be unknown wheel bearing qualities to support the weight of the vehicle as all that remains standard. This layout stems from the recent conversion of a Range Rover and to me makes excellent sense and reasonable ease of fitting. I personally feel there's be less complicated engineering to do to build a frame to take these motors and get new driveshafts made. Not only that they'd be sited away from major dust and 'puddle-splashes'. I think I'm right in thinking that the larger the diameter of these units the more torque is available. 

Don't ask me about the electronic controls but I can't see that as being insurmountable at all.

Perhaps one of the electronic brains on here might want to help in that direction. I'll email the company for more info and will post their responses. In the meantime please can we have some input from experienced converters that can explain the control requirements in the simplest of language [for keen but 'electronically-challenged' stupids like me]? 

I'm happy to be shot down in flames but as I type I'm quite excited at this method of conversion.....


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## major (Apr 4, 2008)

High Tension said:


> I'm happy to be shot down in flames but as I type I'm quite excited at this method of conversion.....


Hi High,

When you move the motors off the wheels and put them inboard, they are no longer "wheel motors". Running the motor at wheel speed is a bad idea. Motor RPM should be 4 to 10 times higher than wheel RPM for reasonable size motor(s).

Multiple motor control is easy when each motor has dedicated controller and run in torque control.

Cheers,

major


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## High Tension (Apr 29, 2009)

major said:


> Hi High,
> 
> When you move the motors off the wheels and put them inboard, they are no longer "wheel motors". Running the motor at wheel speed is a bad idea. Motor RPM should be 4 to 10 times higher than wheel RPM for reasonable size motor(s).
> 
> ...


I agree and stand corrected with your terminology Major, thank you. However, surely these motors are designed to run at wheel speed, inboard or not? They allegedly come with studs and a brake disc to directly accept a road wheel up to 14", 400 - 750 rpm. I thought they'd be better employed inboard for reasons stated in my last post. 

I got a little excited about them as there's the beginning of hope for DIY ers to emulate the big boys without needing to own a bank. As said, I'm sure quality may well be an issue....

http://www.alibaba.com/product-gs/381785732/Car_Hub_Motor.html

What say you Sir?


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## major (Apr 4, 2008)

High Tension said:


> What say you Sir?





major said:


> Running the motor at wheel speed is a bad idea. Motor RPM should be 4 to 10 times higher than wheel RPM for reasonable size motor(s).


I've (and others here and elsewhere have) been thru the reasons many times. I don't have time to do it again. But if you want to try it that way, go for it


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## Gulah (Feb 24, 2010)

major said:


> I've (and others here and elsewhere have) been through the reasons many times. I don't have time to do it again. But if you want to try it that way, go for it


Are you talking about hub motors? They're already spinning at proper speed, I'm not sure about using them as motors, since we would be loosing a lot of efficiency, but I think that they're a good option ...
Can anyone recommend a hub motor? And why should be a separate controller to each motor, if they're controlled by torque they all should have the same torque, so the signal should be equal to everyone; maybe because regenerative braking?
I don't know really, but I'm eager to learn


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## major (Apr 4, 2008)

Gulah said:


> Are you talking about hub motors?


I am talking about motors.



> They're already spinning at proper speed,


That's the problem.



> I'm not sure about using them as motors,


They are motors.



> since we would be loosing a lot of efficiency,


Not really about efficiency.



> but I think that they're a good option ...


NOT



> Can anyone recommend a hub motor?


There are no hub motors for highway capable passenger cars which you can afford and even the ones you can't afford are mostly vaporware.



> And why should be a separate controller to each motor, if they're controlled by torque they all should have the same torque, so the signal should be equal to everyone;


You always want to control torque for EV motors. And you really need to for multiple motors because they can rotate at different speeds in certain conditions. You may want to give all motors the same torque command. And it is possible to use multiple motors on a single controller if they are brushed DC. But because this started with hub motors which are AC, I assumed we were speaking of AC motors and there you will need a dedicated controller for each motor due to unequal frequencies.

Search for hub motors and you'll see. Yes they are available for bicycles, small motorcycles and specialized vehicles, usually very slow or extremely large. But for passenger cars, the hub motor, or wheel motor, or motor-in-wheel remains a product everyone wants and nobody has. Been that way for 100 years. How many do you see on the street? Zero 

Regards,

major


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## Gulah (Feb 24, 2010)

Thanks for answering my questions, yes one of my questions was about top speed, I wanted to believe that with the right controller, or set of controllers and number of motors in the car it would be possible. I guess it isn't then 

Too bad, it's a shame really, still these engines are useful, but only for certain purposes.

But I have a hope, that some day hub motors will be a possible option in a EV conversion.

I know that there are hub motors good enough for highway speed, there was that insane mini, but the problem is the price.

Let's wait and see.


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## Arlo (Dec 27, 2009)

I have been thinking about this for 4 years. What I have seen from building some electric motorcycles and bicycles that hub motors are more weight for less power they are easier to control. (brushless controller wise) But I think the best way is to gear reduce a motor to each wheel and then spin the motor faster this way you can have higher HP with less weight!


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## battlewagon (Nov 28, 2011)

I'm sorry I'm sure this has been covered or is an unreasonable concept, but what is wrong with mounting two motors on the rear drive axle (outside of the hub)?

are there DC motors capable of the necessary performance in a dual setup?


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## Arlo (Dec 27, 2009)

battlewagon said:


> I'm sorry I'm sure this has been covered or is an unreasonable concept, but what is wrong with mounting two motors on the rear drive axle (outside of the hub)?
> 
> are there DC motors capable of the necessary performance in a dual setup?


The Rimac concept one uses 4 individual motors inboard mounted driving through one stage reduction to cv axles.
http://www.rimac-automobili.com/


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## sokon (Sep 15, 2011)

thesilverring said:


> Does anybody have an IEEE membership? If so you could view this article[...]
> This is the sort of thing you are talking about right?
> http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=497248&isnumber=10700


 there you go (see attached)


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## aj2k3 (Dec 29, 2011)

Good evening everyone,
I still have not read all of the pages in this particular thread (though I fully intend to), I did wish to introduce myself and put out there what my project idea is and possibly get some feedback from you guys.
I drive a 2006 Scion tC which is a 4 cylinder, FWD, 2 door hatch. 160 HP. I was thinking of making it a hybrid and putting two in wheel/hub motors for the rear wheels (RWD). I'm not sure if this is possible as there is the obstacle of synergy between a combustible engine and two electric drive wheel motors.
Nevertheless, its a pleasure to meet you all and I look forward to learning what I can.


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## major (Apr 4, 2008)

aj2k3 said:


> I still have not read all of the pages in this particular thread (though I fully intend to),


Hi aj and welcome,

Remember as you read these 466 posts that it has been three and a half years since it was started and zero progress has been made.

Regards,

major


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## UncleBuck (Jan 4, 2012)

Hi Guy's... Trying the same project off myself as I just bought an Insurance accident damaged BMW X 5 for £3K. The front end, engine, gearbox are totalled so got it really cheap !... With that, though of making it Electric. 

4 In hub AC motors like those ?
http://electric-vehicles-cars-bikes.blogspot.com/2010/03/australian-wheel-motor-company-prepares.html

Question I have is as well as driving the wheels, could they also drive a generator to help keep the batteries charged, after all every little helps ?

I was thinking on keeping the full electric pack, along with the alternator to somehow keep that side of things the same, thus being supplied by the 12v battery and the alternator keeping that topped up !

From reading, and it’s a lot ! I feel personally the in hub wheel motor is the best way forward. After that, it’s the battery pack ? then the generation side as I feel as much free energy you can muster is a must to help the batteries stay topped up the better, so at some point Super Capacitors are going to be introduced, maybe to trickle feed the battery pack too ? Then the In house charging to charge at home !

Any more ideas to pencil in….


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## bjfreeman (Dec 7, 2011)

UncleBuck said:


> Hi Guy's... Trying the same project off myself as I just bought an Insurance accident damaged BMW X 5 for £3K. The front end, engine, gearbox are totalled so got it really cheap !... With that, though of making it Electric.
> 
> 4 In hub AC motors like those ?
> http://electric-vehicles-cars-bikes.blogspot.com/2010/03/australian-wheel-motor-company-prepares.html
> ...


Just a note that link was march 2011. I think they ran into heat problems if they ever got that far.
400 hp per wheel is 800 Hp. Not even the 40 ft converted bus uses that much HP going up a mountain grade, passing at highway speeds.
400 Hp = 298.4KW of energy. do the math on Batteries even at 765 Volts
http://www.proteanelectric.com/?page_id=158&post=229
is another.
There already using Ultra caps for Hybrid buses, for the first 10 sec start. These packs are about 3 ftX3ft by 5ft in size. 
there is no free energy, only energy converted to one form or another. and each conversion you loose energy in heat.
Even Solar has to come from a big Hydrogen furnace in the sky. and it is burning out, though it be million of years.
Back to more practical things.
at most a Generator is 80-90% efficient, you still have lost power.
you have friction of mechanical parts,not to mention eddy currents.
with all that said, I am using Traction Motor (200KW) that are fluid cooled for 4 wheel drive direct drive (in the prototype stage, but no implemented yet) I have been using the same Traction motors for Generator and driving, my gear box for a few years, to get actual usage data. I am showing about a 40% usable power to the rear wheels, or about 80KW
it is not as efficient as if I left the Transmission in.
My goal is not to have a more efficient system, but one that can run off many power/ fuel sources.
The most recent actual example of long range is the Tesla, in cars. it is all electric you charge as you go.


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## aj2k3 (Dec 29, 2011)

UncleBuck said:


> Hi Guy's... Trying the same project off myself as I just bought an Insurance accident damaged BMW X 5 for £3K. The front end, engine, gearbox are totalled so got it really cheap !... With that, though of making it Electric.
> 
> 4 In hub AC motors like those ?
> http://electric-vehicles-cars-bikes.blogspot.com/2010/03/australian-wheel-motor-company-prepares.html
> ...


Hi Buck,
I like your idea of thinking. A friend of mine just totaled his BMW so if you're going to embark on a full scale project, starting with a good platform like the BMW is a classic choice.Now, bjfreeman mentioned the voltage to HP requirements and draw problems and does have a good point, 800HP RWD is a lot, but if you're able to supply the power, it would be some amazing power!You had also mentioned the possibility to utilizing the vehicle itself to recharge the battery by various means. I think if you want an EV, go all in. I'd have solar panels, friction brakes, etc. to help replenish teh energy lost by consumption.

I did want to pose a question to everyone here, magnet generators for free energy. I can't tell if it's a hoax or possible. The label "perpetual motion" gets thrown around a lot, but some great minds throughout history have dabbled with the idea and some have even proven some promising results. Just curious...I believe we have enough people here to really make a difference in how we move about the planet and provide means for ourselves.


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## praondefui (Mar 16, 2012)

aj2k3 said:


> I did want to pose a question to everyone here, magnet generators for free energy. I can't tell if it's a hoax or possible.


It's a hoax. Don't waste your time. After an initial starting pulse they may run for a while, but eventually they stop. Think of the apparent "free energy" of permanent magnets as potential energy. Once you attracted an object with a magnet work has to be done to separate them again. Much like gravity.

If you try to obtain more information about the magnetic generator all you will get is an expensive and totally useless ebook.


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## aj2k3 (Dec 29, 2011)

Thank you for getting back to me, I do appreciate it.

So, has anyone made any progress on anything??


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## Hillbilly (Jun 23, 2009)

MTSU Researchers have built a pretty awesome little setup.

http://theage.drive.com.au/motor-news/doityourself-hybrid-20120725-22pc7.html



















http://forums.tdiclub.com/showthread.php?t=369492


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## karlos (Jun 30, 2008)

Thanks for that Hillbilly, most impressive solution which I would love to know more about. Looks like they used a couple of Kelly controllers? 
It almost looks so simple the DIYer could make something similar that works.

Anyone care to explain how the stator would work in relation to the permanent magnets?


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## Hillbilly (Jun 23, 2009)

karlos said:


> Thanks for that Hillbilly, most impressive solution which I would love to know more about. Looks like they used a couple of Kelly controllers?
> It almost looks so simple the DIYer could make something similar that works.
> 
> Anyone care to explain how the stator would work in relation to the permanent magnets?


You would need to set up some "Poles" probably at least three. Place some halbach sensors to tell the controller where the rotor is in relationship to the stator, and then switch the poles of the stator on and off in sequence to create flux.

Craig Carmichael has some detailed plans for free at:

http://www.ElectricHubcap.com 










Cheers,

Hillbilly


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## freddy (May 17, 2013)

Hi Everyone,
Just joined but been following ideas for a while
I spoke to Dr Charles Perry Mid Tenersee State University (MTSU) last month who is heading up the project on the in wheel motor and he's run into problems hence no news since July 2012. He's of the opinion that the motor needs to be a switched reluctance motor (SRM) as with any DC/AC motor with magnets you get back EMF (?)i.e. increased drag/fuel consumption which you don't get with an SRM. He's looking for funding (around $250,000) so if you know anyone?
Also I have spoken to Protean (I am based in the UK and they are local) and they are not interested in talking to anyone with less than a fleet of vehicles. I'm in touch with a Chinese outfit http://www.evmotor.net/kg/eng/index.asp and they have a motor for $1550 then you need the controller. I am reluctant to purchase 2 for testing for reasons already given by other members (overheating etc) so if anyone has an update on reliable and lower cost motors I am interested. My project is a Toyota MR2 which I am planning to convert to a small diesel with electric motors. At a recent Hannover Messe they were demonstrating the VW XL1 which does 314mpg - all current technology - 800cc engine +24hp electric motor


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## Hillbilly (Jun 23, 2009)

Thanks for the link Freddy. I think I may have to try two of those Chinese Units to put into the rear wheels of my '01 VW Jetta TDI. It already gets 45 mpg highway, I may be able to get my canyon driving numbers up a bit with some E-assist. Or maybe a motorcyle?

I think MTSU should launch some sort of crowd funding effort to get their project off the ground. Who knows, I may try to find the time to help.

If you're going to convert an MR2 to diesel, you should go to this site if you haven't already: www.tdiclub.com

Keep us posted! Start a build thread when you get going!


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## freddy (May 17, 2013)

Hi Hillbilly
Thanks for the response and link on the MR2 - will study later - Re: Dr Charles Perry he did mention he was looking for funding I emailed him some suggestions but I'm UK based and don't know what facilities are available in the US - he is amenable by phone but has not replied to my emails (maybe inundated as his Youtube video is everywhere). I'm sure a homegrown solution would be more appealing than a Chinese one - I have tried to get the Chinese to pass on info for a UK fitter/user to compare notes etc but they will not oblige and I have had problems with reliability with Chinese products in the past (hydraulics products)
Re:in wheel - you may want to check out http://www.youtube.com/watch?v=GahcFeTCZgc&feature=endscreen&NR=1 this guy has a revolutionery approach to Liion batteries smaller footprint higher power - he's behind zeromotorbikes - there's an amusing video of him demo product at Jay Leno's garage doing wheelies on his electric bike ( and leaving some very large black tyre tracks on his white floor - JL not amused!)
Coincidentally I am talking to a garage that does TDi conversions- he's not done an MR2 but is up to the challenge - why not I'm paying
Re: VW Jetta - do you have tuning/remap boxes in the US - I have a Ford Mondeo 2 litre TDCi 115bhp with one which has improved from 53mpg combined to now 60mpg (test is fill to brim every time I fill up)


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## major (Apr 4, 2008)

Hillbilly & freddy,

You're wasting your time. The MTSU motor is a joke. Read this thread: http://www.diyelectriccar.com/forums/showthread.php?t=20591&highlight=wheelmotor Too bad that a lot of the photos are gone from it. But it still should be informative and amusing.

major


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## freddy (May 17, 2013)

major said:


> Hillbilly & freddy,
> 
> You're wasting your time. The MTSU motor is a joke. Read this thread: http://www.diyelectriccar.com/forums/showthread.php?t=20591&highlight=wheelmotor Too bad that a lot of the photos are gone from it. But it still should be informative and amusing.
> 
> major


Thank you major but I do not see any reference to MTSU in your link - If you have useful information about this motor then please share it - have you spoken to Dr Perry and voiced/expressed your doubts to him? MTSU is not the only in wheel technology organisation I am in direct contact with. Are you talking to any? The world is full of tyre kickers and cynics, I hope you are not one but are able to bring positive and constructive information to the forum. So please qualify your comments.
Cheers


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