I am building an electric go-kart. I would like to use regenerative braking. I would like to have a brake pedal that controls the amount of torque (slowing the motor and wheels down) that the back emf from the motor creates.
In a hypothetical situation, the motor (90amp 36volts permanent magnet dc motor) will be spun up when the car accelerates. It will then spin freely once up to speed. This part of the circuit I have figured out this part of the circuit already.
(in this image the important switch is the pedal microswitch which closes every time the throttle is engaged Also, the Main, Foward (F) and Reverse(R) notations refer to contractors used to provide power to and switch the polarity of the motors respectively)
If we now treat the motor as a generator, from what I understand the amount of current that we draw from that generator the more torque will be applied to slowing the motor down. If we take the extreme and fully connect the motor leads together with zero resistance the motor will lock up.
Where I am confused is how to draw variable current from the motor and control it with the brake pedal. For safety purposes, I plan on installing a mechanical hand brake as well.
Any help on this would be appreciated, I am sure that I do not have a full understanding of this mechanism.