The so-called PWM is the pulse width modulator, which provides the motor with a pulse with a certain frequency and adjustable pulse width. The greater the pulse width, the greater the duty cycle, the greater the average voltage provided to the motor and the higher the motor speed. Conversely, the smaller the pulse width, the smaller the duty cycle. The smaller the average voltage supplied to the motor, the lower the motor speed.

No matter whether the PWM is high or low, the motor is rotating, and the speed of the motor depends on the average voltage.