# VW Cabrio conversion



## JRoque (Mar 9, 2010)

A forum member, DawidvC, suggested I visited the Australian EV Assn forum regarding a post where they talked about changing an industrial motor's voltage to half (or more) it's rating with the idea of increasing it's output. There I found another forum member, Coulomb, and took the liberty to contact him via email. Here's the exchange:




> > Hello Coulomb,
> Hi!
> 
> > Someone pointed me to this forum posting: http://aeva.asn.au/forums/forum_posts.asp?TID=1237&PN=9
> ...


So there you have it. I quick scan on eBay showed almost all motors are 230/460 that, in theory, would take only a quick rewiring as described in the user's manual to cut it's input voltage in half. The motor's insulation in the motor I mentioned to Coulomb above is rated for 2500V so while you're pushing the motor outside it's comfort zone in terms of amperage, the insulation is likely to take it without much complaining. I've also noticed that most of these motors have their bearings listed or even printed on the plate. I'd look for ones that are sealed and rated for twice the plate RPM.

This single bit of info, thanks to DawidvC and Coulomb, has opened up a very nice avenue in terms of motor availability. Next stop: motor controllers and how to size them properly. I've always heard you really don't want your controller to go over the rated motor HP too much but if I plan to drive the motor hard, I suppose I need a controller with the motor's peak power in mind. Anyone?

Regards,
JR


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## JRoque (Mar 9, 2010)

Hi. I've been doing some shopping:

- Hitachi SJ300, 240V VFD, Sensorless Vector, 5 HP, $317
- 8 x Powerex IGBT, 400A, 600V, CM400DU-12F, $240
- 2 x Kilovac EV200 Contactor, 900VDC, 500A, $76
- Marathon Electric, 25 HP, 230/460V, 3520 RPM, Inverter Duty AC Motor, $476
- RS485 to USB adapter, $12
- Other misc like a vacuum pump, gauge, etc, <$100

Prices include shipping. 

If you've followed Eric Tischer's build thread, you might guess where I'm going with this. I'll try my hand at replacing the AC drive IGBTs with external ones.

I picked the Hitachi controller because it was new, relatively cheap, it's a usable (for tests) 5 HP and had the best written manual form the all the drives I looked at. They also make easily available the service manual for it that include the schematics.

The controller is 200V class because I want to run my pack at ~300VDC or so, though this model allows you to supply external power to the electronic components (ie: 24VDC) so you can run the drive without a bus voltage, hence no dependency on that. There's also freely available software to program it with a computer and a cheap RS485 adapter.

The motor is "inverter duty" which basically means it's wired to at least 2,500V insulation using 'special sauce' copper and can spin to about 5400 RPM safely. The plan, as outlined on the 2nd post, is to wire the motor for 208/230V but run it at about 300V. If I get more money from the money tree, I'll up the system voltage closer to 400V to squeeze extra tears from the motor. I have conflicting reports on the motor weight. Marathon says it's 150 pounds and the dealer says it's 240 with shipping skids. Either those are heavy skids or someone has a bad scale. I'll weigh it when it gets here.

Things are trickling in so until I get the whole bit delivered, I'll have to sit around. I'll rig something up and make the motor spin as soon as it shows up here.

JR


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## david85 (Nov 12, 2007)

I'd be a little worried about the weight of that motor. At nearly 300lbs its very likely to exceed the weight of the original engine in that car. Does that weight include the controller? Do you know the dimensions?

The peak torque is probably just that, and not likely available across the operating range. Probably just for a second or 2 when first stating up.

45kw constant will be a beast though. I suspect my 6000lb F250 brick pickup doesn't need that much to hold 50 MPH of flat ground.
And by the way, I'm still kicking myself for not going with 320V lol.


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## JRoque (Mar 9, 2010)

Well I'm hoping the motor weight is closer to the 150# Marathon says it is and not the 240 the dealer claims. I looked up my car on some user forums and it's understood the engine is about 250 pounds, but I'm not sure.

The controller is that Hitachi industrial VFD in the picture and it weighs 7lbs. But that's not including the external IGBTs I plan to use or the water cooled heat sink, etc.

The motor I mentioned in the 1st post is not the one I got. I was talked out of that by Coulomb as he rightly points out I would need a lot of amps to get that motor to deliver 45kW. I also read on some .gov site that motors that run below their spec'd HP rating become very inefficient. They say that 50% of motors in US are over spec'd and running far below their peak efficiency.

So the motor I got is specified to 18kW at the rated voltage. I will wire it for the lower voltage option but run it at higher voltage in hopes to get more power out of it (within reason). 



> I'm still kicking myself for not going with 320V


and I wish I had your 200A batteries. The most I can afford right now is going to be 320V @ 60A or 100A if I starve the family for a few weeks 

JR


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## david85 (Nov 12, 2007)

You are in good company to be hanging out with Coulomb and his buddies on the aussie website. They have forgoten more than I'll probably ever know about this stuff.

I did not know about the efficiency drop below rated output though. I wonder if that rule applies to BLDC motors? More stuff I have to learn.....

Mine is rated at 20kw, and the car will comfortably cruise at 50 MPH with some extra to push 55 or some power to climb shallow hills at 50. The stars have to align just right to top out at 60 on perfectly flat ground.

I would guess 25kw would be a nice constant output to have with 30 being ideal for our size/weight range of car.


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## JRoque (Mar 9, 2010)

This is not the document I originally read, and it changes some of the figures I previously had, but overall it shows that over-sized motors (by more than 50%) are inefficient: http://www1.eere.energy.gov/industry/bestpractices/pdfs/mc-2463.pdf

In my motor search, I came across AC induction motors efficiencies in the range previously attained only by BLDC, about 96%. If I had to guess, I'd say you'll get much better regen from a BLDC at low RPM than induction so that's one thing they win.



> The stars have to align just right to top out at 60


I bet that with a bit more voltage, if your controller will take it, you can go a lot faster.

The "killer" spec that came up every time to ruin a great deal on an industrial motor was: weight. For about $1000 I could have had a 50HP motor delivered.. but at >500 lbs it was a non starter. The Chinese motors I sourced looked good but I could not get them to give me details on their specs. By "specs" I mean water cooled or not. I may go back to them if this motor I just got is no good.

JR


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## david85 (Nov 12, 2007)

If you go with the chinese supplier, all I can really say is expect to have at least some small problems. Generally the sales reps in companies like this are not very well informed and their only major skill is that they can speak english while their engineers or technicians can't. It can be tedious to get answers out of them even if they are negotiating in good faith.

Once mine was up and running it seems to be reliable, but there are annoying little things that will have to be tweaked eventually. Things like the weak regen anywhere below 4000 RPM and the throttle pedal only taking effect somewhere halfway to the floor. I also cleaned up some of the factory wiring in the motor junction box. Not very big things but basically it meant it was not a turn key operation right out of the box. The motor is also not perfectly balanced and will produce some slight vibration at max RPM. Noise is also noticable at 4000, but its still nothing compared to the original ICE. Its important to remember that these are industrial motors and running perfectly silent and smooth isn't always the first priority.

Don't know yet if I'll try for higher voltage but I am giving serious thought to modifying the controller once I can identify more of the parts on the controller board. The central processor seems to be a standard unit and that generally means you can get a programmer for it. Once I weigh the car, I might just decide that it could be worth wile to add a few more cells down the line. I still have that huge caping hole where the gas tank used to be lol.

Induction motors are closing the gap in efficiency though. Rare earth magnets are also getting better and less fragile to shock or heat but if I had to choose between a 95% efficient BLDC motor or a 94% efficient induction motor for similar cost I think going with induction is a no brainer. They are easier to service and generally more durable.


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## JRoque (Mar 9, 2010)

Excellent information, David, much appreciated. I did ask - and got answered - if their controller was programmable from a PC: it isn't. That was a deal breaker for the controller. 

Changing the final IGBTs/FETs is not trivial in many cases but doable as demonstrated by Eric and others. This particular Hitachi drive I bought seems to be easily modifiable but I haven't looked too much in the schematic yet. One thing is that if I get it modified, I will post every bit of detail needed for others to do the same if they wish. 

Once I have that platform stable, I plan to change and add a bunch of things to it. Things like: don't ever, never regen when taking the foot off the throttle. I can't think of a good reason for doing that and maybe I don't understand it well. But to me, the distance I could travel by coasting the motor/car far exceeds what I can recover by regen braking. In my case, regen would only happen when I press the brake pedal. I intend to setup my brake pedal so the upper third of it's movement range is proportional regenerative braking and the rest is mechanical braking. After all, there will be cases where I'm going downhill/fast with a fully charged pack not stopping me very much.

Then there's S curve acceleration to give max torque a low RPM, safety features like the brake always winning over throttle position when the car is moving at more than 5 MPH - so you can get yourself out of ice/snow/mud and maybe burn rubber once in a while , turning off power steering pump at >25 MPH or so, etc, etc. I can't wait to get started on this stuff!!!

JR


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## david85 (Nov 12, 2007)

JRoque said:


> Excellent information, David, much appreciated. I did ask - and got answered - if their controller was programmable from a PC: it isn't. That was a deal breaker for the controller.
> 
> Changing the final IGBTs/FETs is not trivial in many cases but doable as demonstrated by Eric and others. This particular Hitachi drive I bought seems to be easily modifiable but I haven't looked too much in the schematic yet. One thing is that if I get it modified, I will post every bit of detail needed for others to do the same if they wish.
> 
> ...


Sounds like you will have an excellent build. Can't wait


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## DawidvC (Feb 14, 2010)

Picking a drive that runs from an external supply is a winner! Nice thinking, JR. That means that you are only limited in pack voltages by the IGBT's you use. I hope every EV'er following this route take note of this. I myself will follow the same route, one day.

BTW, most manufacturers seems to be using similar bearings for similar frame sizes as far as industrial ACIM are concerned, so looking at the maximum allowable speeds from one manufacturer will give a good indication of what is allowed for by most. Standard motors up to 132-frame (not certain the NEMA rating) will do 7500rpm, and up to 180 frame size 6000rpm. These are the sizes that are most likely to be used in normal conversions using ACIM, as weight can be a problem for bigger motors, at least for those of us mortals not given to running monster-trucks.

NB - that was just for the lurkers.

Good luck with your conversion - I will be following this thread for sure
Dawid


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## JRoque (Mar 9, 2010)

Hey Dawid, good to see you here. Yes, the DC bus is exposed externally. I'm not sure how the drivers work but they'll likely need full bus voltage so they can pump the upper switch +15V over Vbus.

Man, I haven't started anything yet and I'm already facing questions. I'm working on snubbing those IGBTs so I setup a typical resistor-cap-diode network thinking it would be relatively cheap. Film caps can be had cheap from China.. but those ultrafast diodes at the amperage I would need cost a pretty buck. The IGBT snubber modules with a cap and a diode I priced run about $65 per switch, that is, x 6! 

I did a cursory search around to see what others are using and it seems most everyone throws a snubber film cap on there and call it done. Aren't we worry about resonance/ringing, etc at higher currents? Is the expectation that the bulk caps would keep that under control? Will the classic RCD interfere with regen functions?

Thanks!
JR


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## DawidvC (Feb 14, 2010)

The hi-performance drives we use at work all use an rcd network each phase to positive and to negative - so 2 networks per phase, as well as film capacitors between the positive and negative buses, as well as a freewheel diode between the buses. That should take care of most spikes and ringing in the circuits. It does not interfere with regen at all - to regen, the drive output frequency need to be lower than the motor shaft frequency - the difference determines the amount of regen.

Regards
Dawid


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## JRoque (Mar 9, 2010)

As usual Dawid, great info!

Ok so I think I got some cheap(er) discretes for RCD snubber from Mouser here in US: 2.5uF film caps and fast diodes. I'm a little worried about the low capacitance of the film caps but figure between them and the rest of the bus caps should catch most of the spike. Check out the ripple current handling on those caps, yikes. BTW, I plan to solder them as close as possible to the body to cut on lead inductance. Same for the diodes. Just need to find the right resistors now.

So freewheeling diode beyond the one in the IGBT? I've add them to MOSFET finals but didn't think I'd need them for these big block IGBTs. I suppose I could use one of those I'm using for the snubber.


BTW, the Hitachi SJ300 drive came in. It's a sea of flimsy plastic. I'm sure it does fine when bolted to a wall but man, they cut all the corners when it came down to the frame. In this day and age having a couple digit display just doesn't cut it. I doubt I'll use that remote controller for much beyond a simple test. Other than that, it seems fit for the job... we'll see.

Regards,
JR


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## DawidvC (Feb 14, 2010)

I would get rid of that flimsy case. Put everything in a nice sturdy box and tighten it down, even if you have to use silicon ( we got that in some 150hp+ drives - quite a shock as they cost us R250 000 - about $34 000 you would expect quality  ) to hold it down. Bolt everything securely onto your heatsink. NB: make sure of the recommended fastening torque on the IGBT's - too much and you can damage them internally. If you can, use copper plate rather than busbar, it helps with the high-frequency spikes that will appear in the system. 

The additional freewheeling diode in the drives I mentioned actually sits across the + and - busses. It is only in the bigger drives from that specific manufacturer ( Unico ) and is rated quite small - about 60A for a drive rated 320A.

If that SJ300 drive has another way of communicating with it, either via serial or some kind of CAN protocol, it would be better to use that rather than waste time on that small display. Most drives nowadays have a communication port of some sort build-in. I will see if I can locate some info for you

Regards.
Dawid


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## DawidvC (Feb 14, 2010)

The communication interface is RS485. Here is some info on the protocol and how to wire it:
View attachment appb.pdf


You can get an RS323 to RS 485 convertor on eBay but for interest here is a couple of ways to DIY:















If you do not have RS323 anymore go for a USB to RS485 convertor. There are some easy ways of doing it with hardware yourself, but it would involve more time and would be a project on it's own.

To use it, you can go to this website: http://www.drivemanager.com/products.html and get hold of some of their stuff to talk with the drive.

Regards
Dawid


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## JRoque (Mar 9, 2010)

Yep, we're thinking alike. I already ordered the 485 to 232 converter... more like a USB version but same thing. I need to see if it's isolated or not as it must be. I also downloaded all of the free tools from that link and have them already installed. I'm just waiting for the motor at this point to fire up something and see it spin with the 5 HP drive.

Thanks,
JR


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## JRoque (Mar 9, 2010)

Ok some updates. 

The delivery co called and they're dropping the AC motor today. If I get some weekend time to myself, I'll rig something up to see it turn... and try not to get crisped in the process.

I found some nice 1.5uF snubber caps on eBay.. kinda low on the Farad department but they should be fine when I add the bulk caps, diodes and extra film caps to the bus. I also got me 8 electrolytics at 1200uF each to help stabilize things. The Hitachi drive caps are 400V rated and that's too close to my 320V target bus. The new ones are 550V peak.

The mechanical and layout pieces are starting to clash in my head. I'm wanting to order some copper plates/bars from my metal shop but they only have 0.190" (4.8mm) thick at the moment. That might cause me some issues down the road when trying to solder the caps, etc to it. There's also the planning of how to layout stuff to minimize inductance while allowing air to flow through. The switches and rest of components will be mounted upside-down with the heatsink on top -after all, heat rises.

I also picked up 6 Honeywell Hall current sensors from Azure's eBay store for $90 delivered which is a good price. I still don't know what my Hitachi drive is expecting in terms of current reading so I might have to do some work to make it happy. 

A local (in Florida) Semikron rep office quoted me an entire external 600V/400A IGBT setup that includes practically everything I'd need to drive the motor. The device model is the SKiM 406GD066HD and the cost is $1,075ea. If this exercise of mine fails, I can always fallback on the Semikron. The Tumanako open-source controller team is using a similar module.

The RCD snubber formulas to size those components are killing me! It's becoming apparent that I need to build the unit so I can measure the total inductance and actual voltage spike before I can build one. It seems I will have to have a chicken before I size the egg... or is it the other way around?

JR


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## JRoque (Mar 9, 2010)

Behold the Massive Green Motor Innator!!! Yes, I watch Phineas and Ferb. I'll grow up someday.

Alright, why didn't anyone tell me a 20" long motor was going to be about 20" long??? It's also about 9" wide. I'm hoping the darn thing is going to fit in my car. I couldn't weigh it on our bathroom scale but I can carry it around so I'm guessing 150# is about right. The shaft protrudes 4 or 5" so I might need to cut that too. Oh joy. And this is a 25 HP motor. Thank you guys for talking me out of buying the 40 HP one.

JR


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## david85 (Nov 12, 2007)

Azure has an online webstore? Do you have a link?

Looks like a nice motor but I hope you can fit it. Your VW has a transverse powertrain, yes?


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## JRoque (Mar 9, 2010)

Yes, I bought the 6 sensors from Azure Dynamics Online Sales. They only have 45 completed transactions at the moment so my guess is that they're new to eBay. They're probably running a spring sale of sorts.

The VW Cabrio has a crossed ICE and transmission, I think it will fit. I better build a sturdy base for it because it's way too long to be hanging from the transmission too much. 

I'm a little worried about that shaft being too long to butt to the transmission. Hmmm... maybe I should buy a spare transmission to play with. I want to drive the ICEd car until I have most of the EV parts ready so it's not propped up too long. It would also save me from taking the current transmission out...

I need to go back to your thread, David, and see how you took your coupler and plate measurements, etc.

JR


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## david85 (Nov 12, 2007)

We used our CNC machine as a digitizer to get coordinates for the bell housing and bolt pattern. Then I made a full CAD drawing, then it was transfered back into the CNC software for cutting of the plate. The coupler was outsourced to a machine shop in vancouver that a local hydraulic's shop told me about. Once I had a spline for the motor shaft, I welded the hub from a clutch disk to the motor spline and was good to go.......although much of that will be redone over the next few weeks as we make some improvements to the motor mounts, plate, and restore the clutch function.

I'm a little dumbfounded that AZD has decided to become a retailer. I tried calling them to ask about getting a drive system from them but was refered to CANEV who never got back to me. Thanks in part to that experience, I took my money off shore and they lost out on a potential sale. Could be good news if they are finally willing to not only talk to enthisiests in the field but to actually sell direct to us. Can't help but wonder if it has something to do with their newfound penny stock status


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## JRoque (Mar 9, 2010)

Ok good tip on the plate making. I have a homemade CNC machine I put together several years ago with the excuse that I needed to cut my own PCBs. I ended up with a 5' x 4' (1500mm x 1200mm) contraption that has done everything from wood furniture, doors and frames to improved parts for the lathe... and PCBs too. 

What do you use for CAD? I did AutoCAD for years but switched to Rhino3D (Nurbs) and won't go back. I use VisualMill for g-code generation and Mach3, from brilliant Canadian software architect, as CAM.

I hear you about AZD move into "retail". It's true that us plebe can be annoying at times. But retail/consumer is where the money is. What they, and many others should do IMHO is: get freakin' reps to handle the crowds! What would be of Apple if they didn't sell retail? Having that bit of extra layer between maker and consumer makes all the difference. 

JR


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## david85 (Nov 12, 2007)

Dad bought one of these for getting a center reading for each hole. That what you can jog the machine to get as close to center as possble, then record the location on the read out.










So far we aren't happy with the software for the CNC aspect. I use autoCAD for railing design since I have no need to go all out with rendered parts in that situation and so far am satisfied. We are also running bobCAD for G code generation and we are not happy with it. Frequent crashing, not very intuetive GUI and very limited capability. Slightly more complex 3D parts have a tendancy to jamb the program. A purpose built PC for the machine might be in order though.

Haven't tried the software's you mentioned though. Might be worth looking into.


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## JRoque (Mar 9, 2010)

Yes try Mach3 if you get a chance. It's the best $175 I've ever spent. You can use it for free if your g-code is less than 500 lines. That centering work you mention is done automatically in Mach3 by detecting when the probe contact hits the frame (ie: ground). Three points is all it takes to fall right in the center of a hole. I wrote a macro in Mach3 that automagically sets my Z=0 with a probe. I know Z- means it's cutting and Z+ is not.

VisualMill is a little more expensive at about $1000 when I bought it. But it is industrial strength software and support is fantastic. The $1K I paid also included Rhino3D and that's how I got started with it. 

If you don't need complex 3D machining, Mach3 will generate g-code for you from an imported DXF file. A dedicated PC is best but I run mine on an old Pentium 3 laptop that can only run Win2K since it's so old and slow. 

JR


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## david85 (Nov 12, 2007)

Definately have to look into this. Thanks!!!!


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## JRoque (Mar 9, 2010)

Ok another brief update:

Spent the whole weekend replacing the (freakin') convertible canvas top on the Cabrio. This is not exactly EV related but it might be useful to others considering a VW Cabrio as donor car. I used a top for a '99 model on my '96 since it's supposed to be easier to install. It came out good and I lost 15 pounds during the process so win/win.

I wired my motor for Delta winding and hooked it up to the VFD. I don't have 3 phase power but wiring both hot legs of 240VAC to L1 and L3 worked fine. I also disabled the phase-loss alarm.

Running on V/Hz, the controller would trip with over-current faults on anything past 1.5Hz. After much struggling with the parameters, I remembered Wye start uses less current during startup and wired it so.

For reference, on a 9 lead motor, wired for low voltage (ie: 240VAC), Wye config is:
L1 = T1 + T7
L2 = T2 + T8
L3 = T3 + T9
Then T4 + T5 + T6 tied together

After making this change, I ran the auto-tuning first with no shaft movement, then with shaft turning. I then ran an auto fine tuning routine and finalized the settings. The motor now spins up to 60 Hz with about 13A current, no load.

Now, I've never seen a big AC motor like this one spin but it is too loud in my estimation. I'm suspecting the bearings are either shot or need lubrication. The shaft spins freely but there is a bit of a bump in there that can't be felt on the shaft but it can be heard, consistent with dried up grease. 

Here's a video with the motor spinning up to 30Hz. It's difficult to tell from the video because there isn't a reference to compare but trust me, it's loud!

http://www.youtube.com/watch?v=g6Y9XjZTxtY

So whatcha think? Is this normal or do I need to take it apart and grease it up?

JR


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## dtbaker (Jan 5, 2008)

wow, I dunno, seems really loud, and spun down fast... once up to speed it shouldn't take much juice at all with no load like that....


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## JRoque (Mar 9, 2010)

Hi. Another minor update. The front bearing of the motor was completely busted. I will clean it up and see what happened (it's a new motor), eventually.

The company I bought the motor from sent me a pair of killer, metal sealed SKF & *** bearings. I replaced only the front bearing but might do the back one too before the motor goes in the car. I posted a new video (low quality) showing the motor doing the same acceleration to 60Hz as before. Can you hear it? There's very little vibration even with the motor still sitting on the wooden pallet and spinning to ~3600 RPM.

I've been working out the plan for the accelerator and brake pedals. I've decided to use a standard wirewound pot for acceleration using the existing gas pedal and wire in the car. I will either use negative voltage or something above ground as I don't want to reference ground in this critical application. This will help with noise handling.

For the brake pedal, I'm going to use an Allegro hall effect sensor and some magnets to make a proportional regen brake that operates right before the mechanical brakes do. In other words, regen should stop the car - within a voltage and current limit - before the mechanical brakes take. Anyone else doing proportional regen braking?

I received the aluminum plates and copper bars for the external IGBTs. But that's going to wait until I get more familiar with the VFD and motor now that they're working. I also need a known-good platform to develop the accelerator and brake pedals and don't want the complexity external circuits until I'm done with that.

Low quality pics below show the front bearing and then being pulled out.

JR


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## JRoque (Mar 9, 2010)

Hi. This is going to be one of those late night postings of mine so bear with me if I fudge things a little. 

I want to have regen on my controller only when I press the brake pedal and not when I decelerate. I've built a prototype to interface with the Hitachi SJ300 drive that mostly works except for the bit mentioned below.

Here's what I have:

Acceleration:
1. Pressing the accelerator commands increase in motor speed
2. The motor speed is proportional to the accelerator position.

Deceleration:
1. Cutting back on accelerator so motor speed > accelerator position causes a "Free-Run Stop" command issued to the drive
2. The drive cuts back power (to zero power, actually) and the motor coasts down in speed

Braking/Regen:
1. Pressing the brake pedal causes the speed controller prototype to match the motor speed and then commands a reduction in speed from that point downward
2. The delta between current motor speed and commanded speed (on it's way down to 0 speed) is determined by the brake pedal position, More brake pedal, lower commanded speed.
3. This equates to proportional regen braking.

I cobbled together a few passives, a relay and a microcontroller for the prototype work. I have two levers attached to two potentiometers. These are connected to a couple of ADC channels on the micro. Pushing the accel lever forward causes a proportional voltage to be sent to the SJ300's speed analog input. There's a line from the SJ300's speed analog output that connects to the micro's ADC input. This is all very basic stuff and no problems with that so far.

The problem is that when I issue a stop or free-run stop (ie: coast) command, the SJ300 stops sending the motor's current speed on the analog output; voltage goes to 0. Since I have it set to sensorless vector, I was hoping it would continue to detect the motor speed even when it's not actively driving it. After all, the drive has a function that will decelerate the motor using nothing more than regened power when mains power go out.

Anyone out there with a Hitachi or similar drive that know if it can and should send motor speed even after a stop command is issued? I didn't want to have to deal with actual sensors since my motor doesn't have them and I suspect it will be a pain to retrofit it.

Thanks,
JR


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## Anaerin (Feb 4, 2009)

JRoque said:


> Hi. This is going to be one of those late night postings of mine so bear with me if I fudge things a little.
> 
> I want to have regen on my controller only when I press the brake pedal and not when I decelerate. I've built a prototype to interface with the Hitachi SJ300 drive that mostly works except for the bit mentioned below.
> 
> ...


Is it not possible to keep, say, 5v running through the motor as it coasts, allowing the sensorless vector to keep track of where the motor is?

Also, putting regen on the brake pedal can lead to issues with the crossover from regen braking to mechanical braking. I know some people have found that Regen is kind of weak at braking, and so have 100% regen activated on the brake light, or used a pot (usually a spring-loaded linear slide pot) to control regen amount, or even have it so the first 10% of the accelerator pedal is 100%-0 regen, followed by 0-100% power, to get an effect more like engine (compression) braking on a manual gearbox ICE.


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## JRoque (Mar 9, 2010)

Hello Anaerin, thanks for that! It's the most insightful information I've seen on regen setups. Got any links to possible forum discussions on that topic?

Yes, the crossover between regen and mechanical braking has been a concerned of mine but I was assuming, perhaps incorrectly it seems, that regen would provide all the stopping power I'd need and mechanical will be there only to catch a possible failure. Another EVer here says that he gets more than 100A of regen braking, times his 320V DC bus seemed like enough energy to provide stopping power, maybe not.

Other things making this a difficult implementation are:

- Slower speed stopping power will be nill unless the transmission is used to couple to motor into spinning much faster. For example, shift into 1st gear and then use the higher motor RPM regened power to stop. Not liking that too much.

- Using regen only to stop the car on an uphill will mean it will roll back after stopping. Mechanical braking is there past regen but it will seem unnatural, if not scary to some that you push a certain much but the car isn't stopping.

- Braking would have dependencies on the transmission being engaged on some gear. ie: regen will not stop the car if in neutral.

- The clutch and other transmission components will now be burdened with also stopping the car mass as well as driving it forward perhaps wearing out prematurely.

Maybe some of these issues can be solved by using a brake line pressure sensor, as mentioned in one of the EVTV episodes but perhaps its too much complication for little gain.

Ok, with your help, I'm talking myself out of brake pedal regen. Got anymore reasons to dump it? Or maybe a link to a successful implementation?

Thanks,
JR


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## Anaerin (Feb 4, 2009)

JRoque said:


> Hello Anaerin, thanks for that! It's the most insightful information I've seen on regen setups. Got any links to possible forum discussions on that topic?


I'll try to include links where I can.


JRoque said:


> Yes, the crossover between regen and mechanical braking has been a concerned of mine but I was assuming, perhaps incorrectly it seems, that regen would provide all the stopping power I'd need and mechanical will be there only to catch a possible failure. Another EVer here says that he gets more than 100A of regen braking, times his 320V DC bus seemed like enough energy to provide stopping power, maybe not.


Regen can give you as much deceleration as you get acceleration. So while it may be able to slow you smoothly at traffic lights, it would be no good for an emergency stop. It also only acts on the driving wheels, whereas braking (should) work on all four, so in slippery and/or hazardous conditions, regen alone could cause a skid.


JRoque said:


> Other things making this a difficult implementation are:
> 
> - Slower speed stopping power will be nill unless the transmission is used to couple to motor into spinning much faster. For example, shift into 1st gear and then use the higher motor RPM regened power to stop. Not liking that too much.


Not using Direct Drive? I was under the impression that AC is best utilised with direct drive, as you can command very high custom torque, custom speed, or a combination of the two, and typically get higher RPMs out of AC motors.
But yes, if you're using a gearbox and regen'ing, you have to downshift to get more braking, though then that also leads to the possible danger of overspeeding your motor.


JRoque said:


> - Using regen only to stop the car on an uphill will mean it will roll back after stopping. Mechanical braking is there past regen but it will seem unnatural, if not scary to some that you push a certain much but the car isn't stopping.


Right. Just like using engine braking in an ICE. It would also make hill starts problematic, as you would roll as you took your foot from the combined brake pedal to the accelerator pedal. Of course, if you're a reasonable manual driver, you'll know to hold the car on the handbrake ("Parking" brake as it's called in the US, for some reason), and when the engine has traction release it for a hill start with no roll.


JRoque said:


> - Braking would have dependencies on the transmission being engaged on some gear. ie: regen will not stop the car if in neutral.


Correct. And because you would need more "slack" in the braking system to make room for the regen, it would take a lot more stomping to stop the car.


JRoque said:


> - The clutch and other transmission components will now be burdened with also stopping the car mass as well as driving it forward perhaps wearing out prematurely.


Provided you're not feathering the clutch, it won't much care how the torque against it is being applied, and that's assuming you leave in the clutch. If you're not going Direct Drive, you may opt to go clutchless to make the conversion easier.
The only problem I can see with the transmission is if it wears quite a bit, and you start getting some "slack" in the gears. Then the switching between power and brake will cause failure more quickly. But if there is slack in the transmission, that is going to happen soon anyway.


JRoque said:


> Maybe some of these issues can be solved by using a brake line pressure sensor, as mentioned in one of the EVTV episodes but perhaps its too much complication for little gain.


As mentioned, then you have the problem of having to introduce some slack into the braking system so the regen fires before the brakes, and with the limited pedal travel that braking systems have, that severely limits the amount of braking you can have, and would prove hazardous in an emergency situation.


JRoque said:


> Ok, with your help, I'm talking myself out of brake pedal regen. Got anymore reasons to dump it? Or maybe a link to a successful implementation?


Well, I know Victor of Metric Mind did it with a slide pot, after finding many potential pitfalls with having regen on the brake (His explanation is here: http://www.metricmind.com/ac_honda/throttle.htm)

Eric Tischer did it slightly differently, here's his documentation: http://etischer.com/awdev/inverter.html

I know that when London Transport upgraded their bus fleet away from Titans, the new Optare bus' had "Retarder" brakes fitted on the brake pedal, but it was so difficult to balance the retarders and brakes (As many passengers knew, it felt like the bus' had digital brakes - off or on only) that they recalled the fleet and had the retarders removed.


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## Huub3 (Aug 16, 2009)

JRogue,

I was thinking, wouldn't it be possible to command a very low speed at throttle off (say about 1 km/h).

This would be comparable to the creep-speed with automatic transmissions.

This way the VFD would not go to free-run, but stay in commanded speed. If you then put the coast down decelleration with the throttle on a low value, you will coast for a long time.

When pressing the brake, switch to a mode with higher decelleration value, and do the commanded speed down as you described above. Alternatively you could modulate the decelleration with the brake position.

I see some issues with using regen and shifting, something that also David85 has reported in his set-up. Also I am unsure whether brake pedal regen is really a good idea when on a slippery surface, as you get crosstalk with the safety systems around braking (e.g. ABS and ESP).

Regards,


Huub


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## aeroscott (Jan 5, 2008)

```

```
I was thinking about the shifting issue . I've driven a 1000cc bike with very high max rpm ( 12,000 )ounce in second gear you never need to shift again , say 5 to 100 mph . and you almost don't need the brakes , just work the gas . it's so easy to drive . as I have no experence driving Ev's that shift but some in fixed ratio Ev's ( Tesla , fuel cell Ev's). I would think shifting would not much of a issue . It's not a issue for the fixed ratio cars to Regen very well ( all ac drives). of course they spent unknown money to get there .


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## DawidvC (Feb 14, 2010)

Just a small thought on the regen issue - if you set the accelerator pedal to provide a small amount of regen braking with the pedal released, the car would feel more natural to drive and give you some of the benefits of regen. The rest of the regen can then be provided in conjunction with the normal brakes.

Dawid


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## JRoque (Mar 9, 2010)

Hi all.

I'm not sure what was the thinking process of Metric Mind but I would had never added a pot to the shifter. Maybe I should clarify that one of my design goals is to convert the car so anyone can hop in and drive it without needing a user's manual for thing's we've all come to do almost instinctively. Push the "gas" pedal and it goes, brake and it stops.

Huub, good to see you here. The problem with simply commanding a lower speed is that the controller will do everything it can to lower the speed as quickly as it can. Well, in reality, the controller can be program to ramp down the speed over a longer period but that's not what we need.

In order to make the motor coast, I have to hit the stop button but if I do, the controller stops sending the motor's current RPM. I'll see what I can do with the suggestion of running a small voltage on the motor to keep the vectoring circuit active. 

Perhaps a call to Hitachi support is in order here but regen by braking seems like it's not going to happen for me.

Thanks everyone for your input!
JR


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## TomA (Mar 26, 2009)

> Originally Posted by *JRoque*
> _Maybe some of these issues can be solved by using a brake line pressure sensor, as mentioned in one of the EVTV episodes but perhaps its too much complication for little gain._





> Originally Posted by *Anaerin*
> _As mentioned, then you have the problem of having to introduce some slack into the braking system so the regen fires before the brakes, and with the limited pedal travel that braking systems have, that severely limits the amount of braking you can have, and would prove hazardous in an emergency situation. _


I don't think it works that way, but surely Jack & co will demonstrate this...

The pressure transducer is modulating a voltage across a pressure range. In Jack's case, it is 0-5V, and he has 0-250PSI and 0-500PSI units to test. There are other available pressure ranges. In addition to the pressure range of the unit, there is the programmability of the controller's response to the transducer's signal voltage. On Jack's Curtis, that's pretty straightforward, too, but how to dial it in is the unknown part.

Since brake line pressures skyrocket as braking effort increases, it probably isn't that hard to select a transducer with an effective range below any serious braking effort. If you are trying to maximize regen energy capture, you'd want regen all-in at very low pressures, and size the transducer accordingly; if you're trying to make the brakes just feel boosted, linear and not have a lurch if the controller dumps the regen because the batteries are fully charged, then you might choose a higher pressure transducer and give up some energy efficiency for braking feel. 

Pedal travel isn't really the issue, its all about the pressure. I don't think it is possible to introduce "slack" into the system, nor could doing that actually produce a regen pressure-transduced voltage before the mechanical brakes were activated. The amount of pressure you build is controlled by the diameter of the master cylinder piston, its stroke, and the pedal ratio. None of that changes with the addition of a transducer in the brake line. Moreover, you are either building pressure in the line or you aren't. The brakes themselves operate over a very wide pressure range, and the transducer is responding to the exact same pressure variations. Its a question of choosing the right pressure range on the transducer, and then dialing that signal in to the controller's programming, not adjusting the service braking system in order to vary the pressure transducer's signal output.

Done that way, I don't see a safety concern here, particularly where Jack is driving an OEM vehicle around with this system and it apparently works really well. I would bet dollars to donuts that the braking system on the Go Advantage version of that little van is exactly the same as the ICE powered version, save for the pressure transducer, and (possibly) the elimination of a vacuum booster.

TomA


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## JRoque (Mar 9, 2010)

Hello Tom and thanks for your input.

Right, the brake line transducer might be the answer for a better integration of the two systems. However, if regen is to add any significant braking power to the mix, it should always be a consistent amount. From the previous comments and seeing how regen in general works, this doesn't seem to be the case.

Apparently, you'll get varied amounts of regen depending on a number of factors including how much energy your pack can absorb and how fast the motor is spinning. This might cause the driver some anxiety as the brake pedal travel will change for a given amount of stopping power. The total travel itself might not but if regen is to contribute a certain amount of stopping force but then it's not there (or not consistent) then the brake pedal will seem uneven during braking cycles.

You've probably experienced this when you first get in a car where the brakes take much farther down than the one you're used to driving. That "oh crap I've no brakes!" jolt would be happening quite more often. Unless the amount of regen stopping force added by the motor can be translated to brake line pressure, I don't see how it can be made to always smoothly transition.

Then again, if the regen amount is made to be minimal this might not be an issue - though regen gains would be minimal, which was my point earlier on return on investment for all of this. Let's see how Jack does with this experiment.

JR

PS: to experience the "jolt" mentioned above, drive a Volvo for a bit then switch to an older model Ford.


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## TomA (Mar 26, 2009)

JRoque said:


> Hello Tom and thanks for your input.
> 
> Apparently, you'll get varied amounts of regen depending on a number of factors including how much energy your pack can absorb and how fast the motor is spinning. This might cause the driver some anxiety as the brake pedal travel will change for a given amount of stopping power. The total travel itself might not but if regen is to contribute a certain amount of stopping force but then it's not there (or not consistent) then the brake pedal will seem uneven during braking cycles.


Agreed. I think this is actually the problem Prius owners were complaining of, and Toyota scrambled to reprogram into the cars- lack of consistency and confidence in the braking system due to regen mode and effort variations.

So the solution is to blend regen with mechanical braking so much that it goes from a 6%-9% range extender to maybe 3%-5%, but it never surprises you or exhibits itself in operation. At that point, why bother? We are saying the same thing, JR. 

It further seems that without meaningful regen, a cheaper, simpler DC system with higher torque is the way to go. Wayne at EV-Blue sure thinks so, and he's done this, what, 300 times?

TomA

PS- I have experienced the "jolt" in reverse- years ago, hopping from my 1957 Bel Air wagon (with "mayonnaise jar" master cylinder single circuit manual brakes,) into my mom's late model Toronado, I put everybody hard into their seat belts and four skid marks on the pavement at the first stop sign from the house. Arresting...


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## JRoque (Mar 9, 2010)

Ok, here's evidence of how rough and slow my conversion is going to be. Today I had one of those "oh sh... crap" moments when I took out the measuring tape to see how well my 20" long AC industrial motor was going to fit once I took the ICE out: it won't. The crappy VW engine is only 16" long and there isn't enough room to fit the electric motor I chose. Eying it out it didn't appear to be a problem but obviously I should have measured. Maybe I can use that motor on my other car which is a VW Passat V6.

So, back to square one. Right about now, that HPEV AC50 motor is looking pretty good. I wish they sell the motor only and not packaged it with the controller. Not that the controller isn't good but I already have one that works with most 3 PH motors and it seems wasteful. 

One of the pluses of going with the AC50 is the fact that I would need less cells to reach operational voltage - about half as many as before. This primarily means less fabrication work needed to accommodate the pack. I wanted a higher bus voltage as it is more efficient that way.

So while I had high hopes for a custom controller and ACIM, the AC50 package will get me started quicker so I can concentrate on bigger things like making the transmission plate and coupler... gulp.

Anyone know of a better motor in the AC50 package cost range?

JR


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## david85 (Nov 12, 2007)

Man that sucks. 16" isn't an easy size to find in an industrial motor that still has enough power. Mine is about that size with the fan taken off but as we know they aren't a very good supplier.


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## JRoque (Mar 9, 2010)

Hey David, I wanted your opinion on your current motor and controller. You had mentioned before that you weren't quite fully satisfied with the Chinese vendor of your drive system, but how's everything else? Would you buy a BLDC again (that's what you have, right?) or do you see any advantage in going AC induction? Personally, I can't think of any advantage of ACIM over BLDC, the latter being more efficient.

I have an offer from a vendor and this time this guy has answered ALL of my questions, provided documentation showing electrical and mechanical descriptions and..... wait for it.... prices!!! So I'm rather encouraged this time. The package consists of a 40kW nominal, 80kW peak, water cooled, BLDC motor and a 288V @ 500A peak (250A nominal), water cooled controller. The package is, shipped air via UPS to me, $4300. He's also including an accelerator pedal and some sort of LCD display though I don't have docs for those. The controller does proportional regen on braking (with a pot) just like I wanted. What do you think?

JR


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## david85 (Nov 12, 2007)

JRoque said:


> Hey David, I wanted your opinion on your current motor and controller. You had mentioned before that you weren't quite fully satisfied with the Chinese vendor of your drive system, but how's everything else? Would you buy a BLDC again (that's what you have, right?) or do you see any advantage in going AC induction? Personally, I can't think of any advantage of ACIM over BLDC, the latter being more efficient.
> 
> I have an offer from a vendor and this time this guy has answered ALL of my questions, provided documentation showing electrical and mechanical descriptions and..... wait for it.... prices!!! So I'm rather encouraged this time. The package consists of a 40kW nominal, 80kW peak, water cooled, BLDC motor and a 288V @ 500A peak (250A nominal), water cooled controller. The package is, shipped air via UPS to me, $4300. He's also including an accelerator pedal and some sort of LCD display though I don't have docs for those. The controller does proportional regen on braking (with a pot) just like I wanted. What do you think?
> 
> JR


That sounds like a good deal. Once I got the kinks worked out of mine, it has run flawlessly. There is no regen however. Now that I know the processor in the controller (off the shelf Motorola IC), I can confirm the controller and CPU were never intended to offer dynamic braking although it may be possible to some day hard wire or otherwise trick it. I've even toyed with replacing the brain with a developer's board. Right now it will regen pretty good if it reaches something like 5000 RPM downhill but under that RPM it just coasts. So over all I can concluded that the basic design of my setup is _reliable_, but was not assembled properly in the case of the controller. The motor is crude but does perform. I have no way to confirm at this point if its delivering the rated power however. I still haven't got around to buying the needed instrumentation.

Truth be told if it wasn't for my choice in nominal voltage, there would have been far more options open to me. It could very well be that the company I bought from now has their act together too, it wouldn't be the first time a chinese company did this. 288V is where the good stuff started even back when I was still looking. 144V is only going to get you a 20kw motor at the most when dealing with most companies in china. It is most certainly possible to get more power out of that voltage, but the cost of the motor controller starts to spike up as the current gets about the ~200amp range. Having looked at prices for IGBTs, its clear that those in the higher current range do come with a price premium. This is something I figured out as time went on after I was already running the motor. I suspect that my current setup would adapt fairly well to higher voltage for more power.

The motor got its hottest during a bit of a heat wave when I was trying to sustain about 70 MPH (could have been higher depending on how much my speedometer under estimates). After about 10 minutes at 55, I used a downhill ramp to increase speed and held it at 70 for a few more minutes. Pulled over and the temp of the outside of the case was 70C (158F). Got back in and drove home without any issues. The motor is rated for 155C (311F) according to specs and usually runs between 50 and 60C (122 - 140 F) when measured on the exterior of the case.

The controller will still cut power out if it thinks there is an over current situation, but I suspect its over compenating a little since it runs barely warm on most days. The cooling fans do come on, but as I discovered, they will cycle even if the car isn't being driven! The car is black, the controller is up very close to the underside of the hood and the sunlight alone can heat it up enough to trip the temp sensor on the heat sink. However if I'm on one of my [trade mark] night drives, the fans never come on no matter how hard I drive the car. This also explains why they never came on during my brief testing last winter. So over all I don't think the controller is working very hard at all. I can disable the cut out feature, but until I know more about the amps flowing through it, I'll leave it as is since thats my only real safety net. Its annoying but does work.

One thing I noticed about chinese vendors with price, is they often give you that first thing. In most cases I never had to even ask for it and sometimes I could haggle with them a little. Asking for service on a part you already paid for can be another matter. But again since I already modified my controller case I can't really be too hard on them since that alone could have been grounds to void the warranty (even though it had nothing to do with the internal failure). I never gave them the chance to repair it so we will never know if they would have come through for me. I just wasn't ready to chance it.

My understanding is that while AC motors can peak at similar efficiencies in theory (the ones available to us generally do not however), they tend to peak in a relatively narrow range near their rated output. Efficiency goes down under heavier load as just about any motor does, but it also drops off under lighter load which BLDC motors do not do as much. So peak for peak in theory AC and BLDC can be similar, but across the real world operating range, the BLDC has the advantage. The only possible disadvantage is if the magnets loose their strength due to overheating or physical impact but I suspect those are not really issues anymore even though you can't say perminant magnet without some one brining up the issue of demagnetizing.


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## JRoque (Mar 9, 2010)

Good write up, David, thank you.

On the flip side of the higher 288V controller is the argument that with something like an AC50 and Curtis package, I need only about 36 cells instead of the 90 cells for the higher voltage controller. True that higher volts means lower amps required but that's 90 cells that will need boxing, mounting, strapping and wiring that would go much easier with fewer cells. I'll need to think about that and come to a decision shortly.

BTW, if you go the programmer/developer platform for that MC chipset, you might be able to just flash the one you have now. But you're right that the developer's board should come with all the basic motor functions built-in and swapping shouldn't be too difficult.

JR


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## david85 (Nov 12, 2007)

The IC that powers the driver board in the controller is hard wired. There is no software in it at all. Changes in settings and performance of all operations is accomplished with simple jumpers and resistors on the main board. In theory it makes things dead simple and maybe more reliable but its quite crude by today's standards. Funny thing is the battery charger is controlled by a programmable IC. Go figure. On the upside, I can easily replace the IC if something goes wrong and there would be no loss of programming.

Everything I hear about the AC 50/curtis package is that the setup works very well and will easily out power comparable DC brushed motors in the same size and voltage range.

Cells are generally priced by KWH, not the number of them so cost of a higher voltage battery shouldn't be any higher so long as the reserve capacity is the same. However finding a BMS and charger that can manage that many cells might be a problem. Not to mention wiring it all up. Although depending on what school of thought you follow, BMS is not needed for LiFePO4. Smaller cells for the same relative battery capacity are also easier to fit in tight spaces than large high reserve cells. Not trying to steer you one way or another, just pointing out that there are advantages to both versions.

You might also want to get in touch with Dave at Current EV Tech. He is just starting to offer some BLDC motors that seem to look quite good. Its possible that they are even from the same source that you found. He might be able to offer some insight because last I heard there were some cars that were in progress with some of those motors.
http://currentevtech.com/Drive-Systems/BLDC-Motors-and-Controllers-c67/

At any rate I think there will be others posting results on the web with these motors because I suspect we are just starting a bit of a spike in BLDC motors similar to how LiFePO4 batteries eventually became the new standard. Should be a nice show over the next year or so.


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## JRoque (Mar 9, 2010)

Hey David,

Yes, cost should be about the same for both packs. I was most concerned with the interconnects, strapping and the maintenance of all those cells in a larger volt pack. 

I have been in touch with Dave over his BLDC offerings. At this point it comes down to pricing. Though I would be willing to pay a little extra and buy locally, the China based supplier has given me every bit of information I've asked so far and has the product for immediate delivery, not to mention $1500 cheaper.

What's the KW rating of your BLDC package agaiin? Maybe I don't need 80kW after all and might do fine with their 40kW package. My donor car is relatively small and not that heavy at 2700#.

JR


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## tomofreno (Mar 3, 2009)

How large diameter motor can you fit? The 80kW BLDC motor/controller currentEV is offering for $5.8k is shorter than 16", but is about 11" diameter. Don't know anything about it though. Edit: Duh, see you have been in contact with him.


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## Guest (Aug 27, 2010)

I don't think an 11" motor would fit. You can fit an impulse 9 in one.


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## corbin (Apr 6, 2010)

JRoque said:


> Hey David,
> 
> Yes, cost should be about the same for both packs. I was most concerned with the interconnects, strapping and the maintenance of all those cells in a larger volt pack.
> 
> ...


Hi JR -- where did you get information for the BLDC motors/packages? I'm interested in them for future projects. Do they have a website, spec sheets, etc?

corbin


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## JRoque (Mar 9, 2010)

Hey, thank you for jumping in guys. The motor diameter is 11.8". Are you thinking it would hit the right side axle? One thing is that their controller is huge: 16"Lx12"Dx6"H. While theirs is water cooled, the Curtis is only 10"x9"x4". He says they're working on reducing that size.

Corbin, their website is: http://www.lowcarbon-idea.com. The contact name there is "Chris". Their 40kW peak package is $3700 delivered. They also have controllers rated for 144V but he said they cost more - not sure why, maybe they use expensive MOSFETs on those. His company sells chargers, DC/DC converters, etc and their prices look very good for those as well.

I'll suggest he posts something in the market forum so everyone can jump in and ask him questions.

JR


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## david85 (Nov 12, 2007)

JRoque said:


> Hey David,
> 
> Yes, cost should be about the same for both packs. I was most concerned with the interconnects, strapping and the maintenance of all those cells in a larger volt pack.
> 
> ...


Mine is for 20 kw constant and 40kw peak. So far the car can comfortably reach 55 MPH with a little to spare for 60 on a good day (although again since I am running larger than stock tires it could be my numbers are low by 9% - I have only confirmed my odometer is off by that much). Don't bother asking me my 0-60 performance LOL.
What would be nice is if there was a 30/60kw option because I think that would be a good match for a smaller car. For vehicle weight, my finished car is about 2850lbs just so you can get an idea for how much yours might weigh. I don't remember if you are going for as large a battery capacity but if not, you might be able to match my curb weight.

I can take on any side street hill I encounter in town so far, but its often a 1st gear experience and crawling up at 25 MPH unless I have the chance to pick up speed before. Highway performance is ok as long as I don't ask it to stay above 55 or climb hills (again, not 100% sure on the speed). The two highways here have posted speed limits of 50 MPH (perfect) for a 2 lane route, and 67 (110kph) for an inland 4 lane highway. The inland highway is still fair game becasue others can still get around me if I am doing only 90 in a 110 zone. I've done that with my truck on hypermiling experiments and its not out of line. Although I would really like to get this car cruising at 67 MPH - eventually

As others have mentioned, I would be a little concerned about the diameter of the motor. Measuring the distance between the motor shaft and the right hand side CV shaft would be a good idea before ordering. The controller size sounds almost like mine. It was something like 9.5 x 9.5 x 16. By removing one side of the case and trimming down the cooling fins I was able to just barely make it fit under the hood with a new top cover I made my self.

Where are their motors? I can't find them online.


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## JRoque (Mar 9, 2010)

Hey David,



> Mine is for 20 kw constant and 40kw peak. So far the car can comfortably reach 55 MPH with a little to spare for 60 on a good day


Is that a function of the controller maxing out or battery voltage sag? If I remember correctly, you're running 200Ah cells so that should be fine. The motor's 40kW is equivalent to the AC50 and those are running around doing 70 MPH from what I've read. So if it's not the controller, it might be that the 40kW peak are at low RPM. 

I've mentioned this before but where I live the posted speed limit is always about 20 MPH slower than actual driving speeds. I have to get to 65-70 MPH to keep up with the slowpokes on the far right lane  Fortunately, I have to hills to cope with.

JR


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## david85 (Nov 12, 2007)

Yes I remember you and others from florida mentioning how traffic flows there lol. Although sometimes I take part in similar "phenomena" here too. The new automatic speed limit signs can't keep up with all the drivers blowing by, its hillarious to see them overwhelmed and flashing all sorts of numbers.

According to the ratings, the battery can deliver about 30kw constant and up to 150 kw peak. Peak being defined as up to 15 seconds.

Its most certainly the controller thats holding me back at the moment and I get the feeling that if I could just get that 30kw constant, the car would do quite well. I can't confirm this yet but my hunch is that I am indeed getting 20kw constant, but might not be reaching 40. The motor will spin to about 4400 but torque falls off a cliff above the rated 3500-3800.


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## corbin (Apr 6, 2010)

JRoque said:


> Hey, thank you for jumping in guys. The motor diameter is 11.8". Are you thinking it would hit the right side axle? One thing is that their controller is huge: 16"Lx12"Dx6"H. While theirs is water cooled, the Curtis is only 10"x9"x4". He says they're working on reducing that size.
> 
> Corbin, their website is: http://www.lowcarbon-idea.com. The contact name there is "Chris". Their 40kW peak package is $3700 delivered. They also have controllers rated for 144V but he said they cost more - not sure why, maybe they use expensive MOSFETs on those. His company sells chargers, DC/DC converters, etc and their prices look very good for those as well.
> 
> ...



Awesome, thanks! I can't seem to find any spec sheets for the AC motors. What company actually produces the BLDC motors? Is it Low Carbon Idea?

corbin



corbin


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## Woodsmith (Jun 5, 2008)

david85 said:


> As others have mentioned, I would be a little concerned about the diameter of the motor. Measuring the distance between the motor shaft and the right hand side CV shaft would be a good idea before ordering.


When I was trying to fit a 12" into my MR2 I found it to be a tight fit on paper. I made up a mock up and found that it was a bit too tight on the CV joint at the diff.
I then tried a two piece drive shaft as the CV joint boot clip would be accomodated by a dent in the grille around the brush appertures but then found that there were no variations of available shafts and joints that would work without costly custom CV and shaft work.
Then trying the actual motor, with the coupler and adaptor, I found I lost a little more clearance and it wasn't going to work cheaply at all.

What I am trying to say is that the closer the fit the more accurate a mock up is needed to be sure of clearances before laying out hard earned cash.

I hope you find a few more thou then I did.


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## JRoque (Mar 9, 2010)

Taking a cue from Jack Rickard's "Duh" project, I'm going to name mine "oh Crap!" This is the second oh crap moment. First the AC motor I got was too long by 2 inches. Now I nearly picked up an 11" dia motor that would seem certain to interfere with the axles. It wouldn't be a problem to determine these specs ahead of time if I didn't still have the ICE in the car but I want to drive it as long as I can while collecting the different components for the conversion.

So it looks like I'm stuck with the 40kW motor. Not that I want to drag race or anything but I didn't want to compromise too much when I replaced the ICE.

BTW, not directly related to EV but over the weekend I replaced all 4 struts on my Cabrio with Bilstein brand ones. Wow. 120MPH and the car remained solidly stuck to the road. It did bounce a little on an exit ramp but not a bad upgrade overall. I also replaced all bushings, stops, etc with firmer ones designed for VW's VR6 engine. I think next I'll have to beef up the back springs so it handles the expected +500 lbs of batteries.

JR

PS: Crap!


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## JRoque (Mar 9, 2010)

corbin said:


> Awesome, thanks! I can't seem to find any spec sheets for the AC motors. What company actually produces the BLDC motors? Is it Low Carbon Idea?
> corbin


Hey Corbin, Chris from Low Carbon Idea just registered here and is posting his product information. I started dinging him with questions but feel free to jump in and ask him your own: http://www.diyelectriccar.com/forums/showthread.php?p=200585

BTW, Chris says he can build me a plate and coupler for the 80kW motor so it fits my transmission. He even sent me a picture of a similar setup he's already done. He asked me for drawings of transmission and shaft... if only I had a VW transmission CAD file....

JR


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