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Old 11-04-2014, 10:01 PM   #1286 (permalink)
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OK, I'm just thinking out loud here, but it seems there is a big opportunity with control here.

I was looking at the dual front motor setup for my car, and it seems ridiculously easy. Making the motor mounts for 1 motor or two would be about the same amount of work.

So I'm thinking I really need to try this FWD setup first, then go to AWD. All it will require is an "electronic differential." Since the motor controller is controlling torque, this will almost take care of itself. Just give the same throttle signal to both front motor controllers.

The basic "open" differential is really a torque split device that is supposed to evenly divide the available torque between the left & right wheel in a corner. The speed and speed differential is not important. This all works fine, until one wheel looses traction, and all the torque goes to that wheel.

So, now look at the simple dual AC motor drive setup: Again, the torque is evenly split between the left & right wheels, as requested by the throttle. In a corner, that is just fine, as the speed & speed differential don't matter. If one wheel looses traction, it is actually BETTER than an open differential, as the wheel with traction will still get its proportion of the torque.

So, a simple, "do nothing" approach would work pretty well. Of course, doing something would be icing on the cake! This controller already has some features built in that will help. It seems adding some form of traction control or even biasing the torque request would be possible without much additional effort. In the case of a spinning wheel, the motor controller would see a) a drop in current b) an increase in speed c) no change in throttle. This could trigger a "reduce throttle until current increases" type routine.


- e*clipse
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