I have a 24v brushless dc motor in an electric pushbike. Max current 20 amps. It is currently 320 watts but for legal reasons I will need to restrict it to 200 watts at times.

Any ideas on the best way to do this without compromising the motor?

 

Swager,

I believe what you are referring to is torque regulation for the drive. This feature is used on machines to limit the torque output of the drive. Torque is related to the current by the torque constant. If your drive has a current loop you can adjust the current limit to a lower
value than normal to limit the torque output.

George Younkin