# Are controller outputs filtered?



## atomicsink (Jun 6, 2010)

I always see simplified diagrams of controllers, they use a PWM output to the motor. So is 200 KHz 100 A (for example) going from the controller to the motor? Or is it filtered before the output of the controller? If they aren't filtered, do they need special cables like hollow / flat wire or litz? It seems like a normal stranded cable would need to be really fat at those specs.

I don't have a EV controller to test right now, but an industrial controller I have for my milling machine is unfiltered.

*Edit:*

The issues I'm concerned about are skin effect and also RF transmission, btw. My controller will need to be 3 feet away from my motor unfortunately.


----------



## EVfun (Mar 14, 2010)

I'm not aware of any common EV motor controllers working at such high frequency. Most of the controllers operate around 15 to 18 KHz. The field winding of a series motor is the inductor of a buck converter so the output is not filtered. 3 feet between the motor and controller is not uncommon. I would recommend the motor loop wiring be a couple sizes bigger than the pack side wiring. I generally use 1/0 for the pack and 2/0 for the motor loop. The size needed depends on the current levels required. Remember that the motor current is usually higher than the battery current.


----------



## atomicsink (Jun 6, 2010)

Thanks man, great info!


----------

