[ausev] Dual electric motor questions
mlibrik at att.net
Fri Feb 1 14:13:40 GMT 2008
Chris Robison wrote:
> Through it's possible that one motor will draw slightly higher current
> than the other due to the small difference in back-EMF between the
> motors, I think the motors will share current pretty closely. I don't
> have direct experience with this situation exactly, and I don't know
> anyone who does ... but seriously think the
> difference in torque will be barely measurable.
While I don't exactly drive electric cars, I have used this dual motor
design using e-bike parts on some large load-hauling work-trikes.
I have two vehicles that used paired rear wheel hub motors, and they
balance out just fine with no evident pull to one side. The pair of
motors can also propel a vehicle through a very tight turn smoothly. I
suspect this is a good way to go, so long as the motors can be mounted
firmly to the chassis. If space near the old engine mount permits then
a pair of reduction gears could be mounted up there as well, letting you
increase the size of the chainring at the motor.
I might suggest using a separate controller for each motor, biasing the
throttle input between them for differential control, if you wish. I
don't bother with this such biasing, but then my stuff all tops out
around 20 mph.
> You may at least want a lower gear ratio than 3:1. Assuming a 20" tire
> on a compact car, that gives you a 120mph top speed at 6000rpm...
As to the one-speededness of the vehicle, that may be a good thing in
the big picture. Why does anything really need to go faster than
30-35mph anyway, aside from habits imposed by the bad old way of doing
things? While EVs are a great solution to the pollution being produced
in cities, the underlying problem of energy consumption, as well as the
oft-neglected matter of public safety, is mainly addressed by driving
Mike Librik, LCI #929
Easy Street Recumbents
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