There are two distinct types of electric bike controllers designed to match
either a brush or brushless motor. Brush motors are becoming less common due to
their intrinsic lower efficiency. And brushless motors are becoming more common
as the cost of controllers continues to decrease.
Electric vehicles require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally provide potentiometer-adjustable motor speed, closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of vehicles limits recovered energy.
Protection logic for over-voltage, over-current and thermal protection