# Hub Motors for cars



## Jonny (Feb 7, 2014)

Just wondering if any of you have had success with hub motors for cars. Ideally 10 kW, but at least 7 kW.
There is a company "Kelly Controls" claiming a 7 kW one for $799, but, the wires look too small, plus their performance graph looks bogus since it shows constant speed - it does not go down to zero rpm.
Also, on Alibaba there are 10 kW ones at http://yzkg.en.alibaba.com/ but the wires look pretty small too.
Thanks for any feedback,
Jon


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## major (Apr 4, 2008)

Jonny said:


> Just wondering if any of you have had success with hub motors for cars. Ideally 10 kW, but at least 7 kW.
> There is a company "Kelly Controls" claiming a 7 kW one for $799, but, the wires look too small, plus their performance graph looks bogus since it shows constant speed - it does not go down to zero rpm.
> Also, on Alibaba there are 10 kW ones at http://yzkg.en.alibaba.com/ but the wires look pretty small too.


For a highway capable real car? Forgetaboutit! Search for wheelmotor, or hub motor, or motor-in-wheel using the forum search tool. It has been discussed to death. Here is an example, a thread which ran for years: http://www.diyelectriccar.com/forums/showthread.php?t=20591&highlight=wheelmotor


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## Karter2 (Nov 17, 2011)

http://sports.yahoo.com/blogs/motor...s-making-wheel-electric-motors-170211509.html



> Protean has inked a deal with FAW-Volkswagen, announcing plans to integrate its innovative in-wheel system into the brand's upcoming electric sedan.
> FAW-VW, a Chinese automaker that's part-owned by Volkswagen Group, utilizes a previous-generation Jetta sedan as a base for its Bora sedan that serves its Chinese marketplace. The automaker sought an all-electric version of this car, and with its new partnership with Protean, it plans to incorporate an in-wheel motor into each one of the rear wheels, turning the front-wheel drive sedan into a rear-wheel drive electric vehicle.



http://www.e-traction.eu/products/thewheel/thewheel-sm440


> *Specifications of
> TheWheel SM440*
> 
> 
> ...


http://www.youtube.com/watch?v=Yv571cJD-X4


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## major (Apr 4, 2008)

Karter2 said:


> http://sports.yahoo.com/blogs/motor...s-making-wheel-electric-motors-170211509.html
> 
> 
> > Protean has inked a deal with FAW-Volkswagen, announcing plans to integrate its innovative in-wheel system into the brand's upcoming electric sedan.
> > FAW-VW, a Chinese automaker that's part-owned by Volkswagen Group, utilizes a previous-generation Jetta sedan as a base for its Bora sedan that serves its Chinese marketplace. The automaker sought an all-electric version of this car, and with its new partnership with Protean, it plans to incorporate an in-wheel motor into each one of the rear wheels, turning the front-wheel drive sedan into a rear-wheel drive electric vehicle.





> *PML Flightlink* were a Hampshire based firm specialising in the design and manufacture of "pancake" (flat) electric motors. The company operated for over 30 years in a number of markets including defense, aerospace, mobility, motion control, processing and printing.[1] In 2006, they demonstrated an in-wheel electric motor for cars called the Hi-Pa Drive at the British Motor Show in London, using a Mini dubbed the "Mini QED" as a demonstration object.[2] Two other car manufacturers have also presented concept cars using this technology: Volvo in its Volvo ReCharge, and Ford with a Ford F150 pick-up prototype presented at the 2008 SEMA Show in Las Vegas.[3]


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

Déjà vu all over again


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## palmer_md (Jul 22, 2011)

given that several major manufacturers have tried to build one and then they all go silent and deny that they tried (dont want to show the could not do something), it seems as if it is not technically possible. To build an efficient electric motor you need to have some close tolerances between the moving parts, and when you put it on a wheel, you really stress the bearings and other items keeping things in alignment. I bet they all discovered that the motor all of a sudden becomes a high maintenance item to keep all this working well, so they abandon the project. 

I also don't understand the fascination many people have with the idea of a wheel motor. I really like the 4 motor setup Rimac has on the Concept1, and no wheel motors required.


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## sunworksco (Sep 8, 2008)

It is like putting jackhammers on the wheel. More asphalt hammering and less control.


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## Karter2 (Nov 17, 2011)

There are some major technical issues to be resolved before the wheel motor can be considered commercial. However, their potential benefits are such that several companies persevere with development programes, and indeed are making positive progress. 
The saga has been dragging on for years, but no more so than electric transport in general, and EV cars in particular.
Protean's tie up with FAW VW is new, and if any one will drive further progress it will be the Chinese.
Personally I also favor the inboard motor option, but that has many of the same issues as the wheel motor......namely, low rpm, high torque and efficiency.
I'm sure Rimac would have preferred not to have used 4 reduction transmission units, but I guess they were not able to produce the torque without using higher rpm motors......ditto Tesla !
So, let's hope the wheel motor becomes a practical option, as it's development may yield a new generation of low rpm, high torque motors.


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## Stefeb (Feb 9, 2014)

major said:


> For a highway capable real car? Forgetaboutit! Search for wheelmotor, or hub motor, or motor-in-wheel using the forum search tool. It has been discussed to death. Here is an example, a thread which ran for years: http://www.diyelectriccar.com/forums/showthread.php?t=20591&highlight=wheelmotor


Let's check this one http://in-wheel.com/ , the LEV motor (on the right side of the page) might be appropriate...


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## toddshotrods (Feb 10, 2009)

What about EnerTrac? They've been selling for years, have been raced, etc. I know they're made and marketed for motorcycles, but aren't they still, technically, a hub motor; and proof that the concept is at least viable?

FWIW, I am not supporting, or arguing for, hub motors. Just curious. I tend to prefer having a vehicle's mass as centralized as possible.


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## major (Apr 4, 2008)

Stefeb said:


> Let's check this one http://in-wheel.com/ , the LEV motor (on the right side of the page) might be appropriate...


Very nice presentation. But I've seen it all before, many times. Like TM4, http://www.tm4.com/en/history.aspx#1982 They started wheel motor development in 1982. Showcased it at all the EV shows and symposiums. Nice presentations. 24 years later they finally see the light and drop the wheel and today make centralized motors. Get the picture?


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## Nabla_Operator (Aug 5, 2011)

just for the record: here's a german company in the netherlands that (still) believes in hub motors:

e-Traction


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## RIPPERTON (Jan 26, 2010)

In wheel motors are completely unfeasible.
But Im convinced inboard or centrally mounted outrunners connected by shafts to the rear wheels only are the most efficient and cheapest way to propel a commuter vehicle.
No gear cutting differential parts. No oil. No frictional losses.
Only problem is this kind of motor cannot be bought over the inet atm.
You would have to make it yourself.
I am planning to double the size of my twin hub motors that I decommissioned out of my Mira and install them in a VW beetle. Another future project.


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## Karter2 (Nov 17, 2011)

RIPPERTON said:


> In wheel motors are completely unfeasible.


^^ Too much of a "catch all" statement . !
There are already millions of "in wheel" motors sold and in commercial use, powering things a diverse as Ebikes, scooters, to earth movers, and Moon Rovers!.
Direct coupled, gearless, hub motors for cars are not yet practical, 
or "optimised" for general car applications, but that is a specific application.

However, i do agree that inboard motor mounting is a better solution with current technology.


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## Karter2 (Nov 17, 2011)

how do you motor experts interpret this statement from Protean ?



> "Protean Drive is self-contained, in-wheel motor technology. Each dc-powered motor includes a built-in inverter, power electronics and software, as well as liquid cooling ports. Probably the most unique aspect is that* each motor in this F-150 application has eight sub-motors*," Prucha said.
> The eight sub-motors can operate together or in any combination.
> "This setup provides redundancy. So if one of the eight sub-motors fails, the other seven can continue to operate. The sub-motor concept also facilitates operating at optimum efficiency. For instance, if the vehicle is operating at a speed and load below the efficiency map's sweet spot, software controls can temporarily turn off a sub-motor so that the remaining sub-motors have to work harder—putting those sub-motors into a sweet spot for a net gain in efficiency," explained Prucha.
> The sub-motor concept and the stator design facilitate automated assembly.
> "By partitioning the motor into sub-motors, we can use smaller devices that are better suited to automated assembly techniques. The proprietary methodology we're using for the automated stator winding means we can get better 'slot-fill,' which correlates to an electric drive system with more power and better efficiency,"


This PDF is a good summary of the current "state of play"
http://www.google.com.au/url?sa=t&r...=4bc5DkliKET4FWywC_r7eA&bvm=bv.61535280,d.dGI


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## sunworksco (Sep 8, 2008)

The sprung weight of 8Lbs. is lost for every pound of unsprung weight loss.
You can also think of each corner of your suspension as Jack hammers. The heavier the unsprung weight, the harder the pounding of the road with the wheels and less control of the steering of the wheels. This means a lot when you are cornering and also driving long distances. You will arrive less fatigued at your destination.


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## Karter2 (Nov 17, 2011)

sunworksco said:


> The sprung weight of 8Lbs. is lost for every pound of unsprung weight loss..


 ?? ..sorry, you lost me with that ??



sunworksco said:


> You can also think of each corner of your suspension as Jack hammers. The heavier the unsprung weight, the harder the pounding of the road with the wheels and less control of the steering of the wheels. This means a lot when you are cornering and also driving long distances. You will arrive less fatigued at your destination.


 Well you might "_*think*_" that, and certainly there are many theoretical issues with unsprung weight, but you obviously ignored that PDF article where the effects have actually been tested..
..
[QUOTE“]....The myth surrounding the issue of
unsprung mass is a pure misconception,”
states Barker. “There were some downsides to
the vehicle dynamics behavior, but you’d have
to be a specialist in vehicle dynamics to notice
them._* The average man in the street wouldn’t
notice the difference at all*_.”
In fact, Whitehead even goes so far as to
compare the effects of unsprung mass on the
tested Focus to “a car in the middle of a
development process, as opposed to a car that
was undriveable or a car that needed new
suspension geometry”. The Protean Electric
director suggests that “there are actually
probably more benefits to using in-wheel
motors in terms of ride and handling” once
advancements such as torque vectoring are
taken into account.
Ford has also undertaken testing in
this area with the Fiesta E-Wheel Drive
development vehicle. Roger Graaf, Ford
Europe’s project manager for research and
advanced engineering, claims, “_*Test drives
have clearly shown that the driving behavior
of this test vehicle in terms of comfort and
safety has remained at virtually the same
level, despite the higher wheel-sprung masses
compared with the conventional basic vehicle*_.”[/QUOTE]


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## toddshotrods (Feb 10, 2009)

Karter2 said:


> > each motor in this F-150 application has eight sub-motors


Fascinating! I had a bright idea once to use three motors inside a wheel, with a gear reduction system I was also designing, but never pursued the idea because of the unsprung weight thing...

I will admit that my concept was totally for theme and aesthetic. It was for my old two-stroke, Kaw-triple, motorcycle - reconstituted as an "EV triple". I think I may have even posted some CAD renderings of it in the Scratch thread.

This makes me want to explore the idea again. And, also makes a lot of sense why Protean is so sure they're onto something, and so secretive. They're actually not building a traditional hub motor - they're building a compact, traditional-ish, drive system that fits in the wheel...


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## Karter2 (Nov 17, 2011)

I dont think they literally mean 8 conventional motors, at least that is not what i get from this..


> Sub-Motors = Multiple autonomous motors each with its own micro-inverter and sharing a common rotor -Patent grantedSub


http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CEoQFjAE&url=http%3A%2F%2Fwww.proteanelectric.com%2Fwp-content%2Fuploads%2F2011%2F12%2FProtean-Electric-presentation-for-PAES.pdf&ei=Utr-UoiSJIbRkQWw7oD4Aw&usg=AFQjCNEHH9X6jiFDq2kXUtwjpQJgC_I71w&sig2=JGJ4lzroBbXtOuDe19atZA&bvm=bv.61535280,d.dGI


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## toddshotrods (Feb 10, 2009)

Karter2 said:


> I dont think they literally mean 8 conventional motors, at least that is not what i get from this...


Ahhh, I see - thanks for the clarification.

That's pretty interesting. So each "sub-motor" only has to pull the rotor 45-degrees, for each turn of the wheel? Is that how you see?

If so, that would seem to lend itself to almost stepper motor like control of the wheel. Just with conventional AC control technology, the hybrid performance cars are already starting to employ "negative torque" (I believe that's how they phrased it) to the inside front wheel to help turn the cars around corners.


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## Karter2 (Nov 17, 2011)

> So each "sub-motor" only has to pull the rotor 45-degrees, for each turn of the wheel? Is that how you see?


 Im afraid it beyond me, maybe this is an "8 phase" motor design ??

browse some of the PDF papers on this page.
..interesting stuff.
http://www.proteanelectric.com/en/white-papers/


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## PStechPaul (May 1, 2012)

That's quite a nice presentation, and if the specs are true then it is a viable concept worth looking into. It seems like the 8 motors in each hub are essentially linear BLDC motors each of which operate over 45 degrees of arc, essentially like a 16 pole AC motor. So the base speed would be 3600/8 = 450 RPM at 60 Hz and 1800 RPM at 240 Hz. 1000 RPM is 70 MPH with 24" diameter tires, so it seems this design up to 2000 RPM is for racing rather than normal consumer use. But if the 500 N-m or 370 lb-ft continuous torque is true, four of these would be able to negotiate a 32% slope or 3.2 m/s^2 acceleration or 7.1 MPH/sec for a 4000 pound vehicle. And maximum torque is 50% higher. Still hard to believe 86 HP in a 68 pound motor 16.5" diameter and 4.5" thick.

The downside may be the reliance on rare earth magnets and the problem of sealing the motor against environmental contamination such as water, salt, and sand.


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## Karter2 (Nov 17, 2011)

One of those papers goes into detail as to how they address the various sealing issues.

i noticed this comment also ..


> Prototype manufacturing will begin in early 2013 with volume production in 2014, out of Protean’s new manufacturing facility in Liyang, China.


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## toddshotrods (Feb 10, 2009)

PStechPaul said:


> ...It seems like the 8 motors in each hub are essentially linear BLDC motors...


That's what I was getting at, but I have only skimmed the PDFs so far, and didn't want to get my knuckles rapped again for assuming things. I was thinking that it seems more like groups of linear motors, but the fact that they're operating in arcs made me bite my tongue - in case there was a more technical description for such an animal.






PStechPaul said:


> ...The downside may be the reliance on rare earth magnets and the problem of sealing the motor against environmental contamination such as water, salt, and sand.


Everyone is high on magnets right now (manufacturers); except Tesla. I get the feel that it's just a more elegant (economically feasible) path to power, that suits their corporate philosophies. Mainly because Tesla has proven that induction can produce big power as well, and one of the traditional musclecar tuners has set its sights on the Model S, promising even more power in the package.





Karter2 said:


> ...browse some of the PDF papers on this page.
> ..interesting stuff...


At this rate, I am never going to get my work done tonight.


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