Controller.
Two different types of controllers are designed to match brushed or brushless motors. Brushless motors are becoming more common as controller costs continue to decrease. (See the DC motor page, which covers the differences between the two types.) )
Brushless motor controller: The electric bike requires a high initial torque, so models with brushless motors typically have a Hall sensor shifter for speed and angle measurements. The electronic controller is assisted by sensor input, vehicle speed and required force. Controllers typically allow input via a power meter or Hall-effect twist (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, overvoltage, overcurrent, and thermal protection protection logic. Bicycles with pedal assistance usually have a disc on the crankshaft with a magnetic ring coupled to the Hall sensor, which produces a series of pulses that are frequencyed in direct line with pedal speed. The controller uses pulse width modulation to regulate the power of the motor. Regenerative braking is sometimes supported, but not often, and the quality of the bike is low, limiting the energy recovered. A 200 W,24 V brushless DC (BLDC) motor is described in the application notes.
Controllers with brush motors: Brushed motors are also used for electric bicycles, but are becoming less common due to their inherent low efficiency. However, since the controller of the brushless motor does not require Hall sensor feedback, it is often designed as an open-loop controller, making it simpler and cheaper. Some controllers can handle multiple voltages.
