apposed electric motor control

[innovationguru]

hi
My brother and I are currently building a electric drive car.

I came up with the idea of using two apposing dc motors on a front wheel drive Honda. not being a electronics expert, is there a way to synchronize the motor rpm in a opposed fashion
or does the power you submit to the system do that for you.
and could you run both motors from one controller?

lets assume that the dc wound motor will run in any direction depending on how it is set up.

thanks in advanced for any insight you could offer

 

[sreid]

Since PWM inverters are usually used to drive DC motors, the command from the throttle should ask for current to the motor (creates torque). You don't want to try to synchronize the motor speeds. For brush type DC motors you can connect the motors in series and use one current mode inverter. Asking for negative torque provides electronic breaking and energy recovery.

 

[jraef]

You cannot have 2 DC motors running the same speed in opposite directions from the same drive. The drive determines the orientation of rotation. You could do it with 3 phase AC motors run by one drive by wiring the motors to turn in opposite directions however because with AC motors it is the motor connection that determines relative rotation.

The question is, why 2 motors? As you drive on curves you will need to coordinate speeds because of the different arcs of the curves between the inside and outside motors. That makes the control system infinitely more complex. Either use just one wheel mounted motor or adapt a single motor to fit to a differential gear system already in use, i.e. replace the engine.

 

[wrsharper]

I must be missing something here. If there are two DC drive motors (one per wheel I assume) then one of the motors leads could be reversed to get them driving in the same direction?

 

[ScottyUK]

Depends if you want closed loop control of the speed or not. Also consider the effects of cornering which are normally taken care of by a differential.


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Sometimes I only open my mouth to swap feet...

 

[itsmoked]

I bet the fraction of a revolution involved in turning makes no difference with regard to this discussion if the OP is using any form of scalar,(non-closed loop), drive. (No paper web here..) ha!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[wrsharper]

Sometimes this forum get vicious, kinda like salt and pepper.