In wheel hub electric motors??

11720 Views 39 Replies 13 Participants Last post by Duncan, Nov 11, 2017

Prideisdead

Discussion Starter · May 18, 2017

Hello.
Im new to this forum.
I have a intrest in EV cars and looking to do a budget build.

But firstly doesn anyone know of in in wheel hub electric motors?
I recent read a article about a university that converted a frwd car to awd and had two in hub motors in the rear tires. Supposedley only costing $3000. $3000 sounds very low for this type of build but i was intrested in the in wheel motors.

Anyone know where to start looking for one?

Or maybe even a motor that would connect to the drive shaft of a rwd.

Im intrested in keeping the engine in place and having some type of hybrid build.

Has anyone done this successfully?

Any belp would be appreciated.

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dcb

· #11 · Oct 12, 2017

fyi the need for delta/wye switching (like series parallel switching) is largely overcome with a better controller and battery.

You *can* change the peak torque/peak rpm with pole changing motors (non linearly) in an induction motor at least, but with bldc/pmac I doubt it since the poles are fixed by the rotor.

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dcb

· #18 · Oct 17, 2017

izzzzzz6 said:
can change the wiring from Delta to Star mid rev. This acts like an electronic gear to some extent thus potentially helping to eliminate the transmission,

I don't think it does actually, that was more of a hack for controllers that couldn't deliver a lot of current or voltage.

however pole changing does have potential, as you are changing the circumferential distance between the poles on the fixed vs rotating bits, and the attraction isn't linear with distance.

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dcb

· #20 · Oct 17, 2017

WolfTronix said:
Delta is about twice the RPM, and about half the torque of Wye.
Wye is about twice the torque, and about half the RPM of Delta.

The thing is (and I assume you are aware of this) that it is probably current limited by the controller (and/or rpm limited by bus voltage).

So that a better controller/battery will negate any benefit from delta/wye switching, and is much simpler conceptually. In delta each phase is seeing 1.73 times less current unless you dial up the current from the controller. In wye it takes 1.73 times more voltage to cancel out the back emf at a given rpm.

This isn't the case with pole changing (i.e. dahlander) motors I don't believe. You can change the toque/rpm capabilities of the machine. So while delta and wye (as a machine with its own limits, independent of controller limitations) operate in the same torque/rpm modes, pole changing can indeed act like a gearbox, kinda, within limits.

I did an armchair analysis of ABB motors here:
http://www.diyelectriccar.com/forums/showthread.php/number-poles-revisited-again-164921.html

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dcb

· #33 · Nov 3, 2017

well you can start with this very thread
http://www.diyelectriccar.com/forums/showthread.php/wheel-hub-electric-motorsii-184393.html

and expand your search to the entire site with some googlefu
https://www.google.com/search?q=hub...m/forums&oq=hub+motor+site:diyelectriccar.com

But basically:

lots of unsprung weight, poor handling.

low torque (lack of gearing, otherwise 350nm isn't too shabby), might get stuck on a hill etc.

low power, comparatively. If you geared these down so you could climb a hill, you would have a top speed of like 10mph.

electrical bits splashing in puddles.

bouncing your motors off of curbs and ruts.

more rotating mass, more energy consumption.

less room for things like brakes.

motor cables flexing and work hardening, and generally being more exposed.

Virtually nobody does it, and those that do don't share all the relevant details, success is measured by if it backs out of the garage with little to no assistance.

etc. etc.

they are fairly practical on a commuter bicycle fyi, and with various mods you can push them hard enough to actually be good. But those are simple no suspension and already lightweight machines.

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