PWM speed control system of DC motor based on AT89S51

This paper presents a new approach of DC motor PWM speed control, using microcomputer as controller, after discussing conventional cascade speed control. It introduces the principle of DC motor PWM speed control and the details of the realization of the approach base on AT89S51 single-chip microcomputer. Different duty cycle quadrate waves are produced by the PI of AT89S51. Different speed grades and the direction are depended on different buttons. Experiments have proved that this system is of higher performance.