Hub motors for cars

[Desertprep]

For the past five years I have been fantasizing about electric hub motors for cars...OK, OK, my life is pretty boring but exciting in the gadget arena. This post was inspired by a quick trip to alibaba.com, the website for Chinese factories to market their goods abroad.

There are several hub motors for cars available now. The one I looked at was available in up to 10kw sizes (http://www.alibaba.com/product-gs/200820249/Electric_Car_Hub_Motor.html)

I felt quiet inside as I read this webpage because I started to see potential for those of us who are the homespun visionaries for a cleaner, purer form of transportation. We now have the tools. The time has come. I don't know how much these are - my guess is that if you bought 100 of them at one time and bargained they would be $400 or so - time to band together to do great things 4 kw is more than 5 hp....10 kw is 16 hp....lots can be done!

Anyway...so much for philosophizing. If I installed four of these hub motors on an electric vehicle would I need some kind of differential? I have heard a number of people make the argument that I would not. Is that true? I remember reading in popular science a number of years a go an article about GM. They had made a prototype car that looked like a skateboard because it had 4 hub motors. It seems within our grasp...the question is how to control them?

Note: I just looked further at http://www.alibaba.com/product-gs/200820360/Brushless_Motor_Controller.html It looks like someone has already thought this through

 

[Dr. Shock]

No, I don't think you'd need a mechanical differential, as there's no mechanical linkage. Most of the time, you'd only have one wheel getting power, so the others would just spin at the rate they need to make it through the turns.

What you'd want is a sophisticated power controller that would send power only where it was needed. If you were accelerating hard, you'd want power to all four wheels, but if you were cruising at speed, you'd just need a little power to one wheel.

You'd also want some traction control so that if a powered wheel started slipping, power would back off and shift to another wheel. To emulate a differential, you could have the computer calculate the turn radius and speed up the outside wheel to match the inside wheel, assuming power was going to both at the same time.

That hub looks like it would bolt right on to the back of a bmw motorcycle.

 

[Desertprep]

I am hoping it will. China also sells a motorcycle that is a design used for the 1930's-40's bmw cycle with a sidecar. It is really cool but the quality of the motor is a bit questionable. I want to look at ways of connecting a hub motor to this set up and having an electric motorcycle with sidecar that I can toodle around in.

 

[Dr. Shock]

I was thinking of the modern BMWs that attach the rear swing arm to only one side of the hub. Sounds like a good project, though, especially if the sidecar also has a driven wheel.

 

[Mathurin]

I am hoping it will. China also sells a motorcycle that is a design used for the 1930's-40's bmw cycle with a sidecar. It is really cool but the quality of the motor is a bit questionable. I want to look at ways of connecting a hub motor to this set up and having an electric motorcycle with sidecar that I can toodle around in.

Sounds like the Russian Ural motorcycles, ancient BMW heritage etc.

http://www.advrider.com/forums/showthread.php?t=158395

 

[Desertprep]

Yes, the Ural is virtually the same AFAIK but I believe the ChangJiang (Chinese version) had a much longer production life - it is still being produced to this day. BTW, looks like a neat project...but do you think you could make it electric?