Title Design on the control system of brushless DC motor
Abstract
Brushless DC Motor with permanent excitation is a new special motor developing in recent years, which changes its phases through the electronic units. It is a production which includes the feature of mechanics and electrical engineering. This new motor has not only the same good characteristics of speed control, high efficiency and high rise torque as traditional DC motor, but also the same good characteristics of simple structure, stable reliability, easy maintainance of AC Motor Brushless DC motors.
At the beginning, we illustrate the fundamental components and the basic working principle of PM-BLDCM. Then the control strategy is introduced at the aspect of theory. A speed governing system of DC-motor by using AT89C51 microcontroller is introduced .The system includes the setting of speed the displaying of speed,the measurement of speed ,aubidle and visual alarm and the control of speed. This paper introduces a kind of method Of DC-motor speed modification based on PWM theory by the SCM. Showing some relative knowledge upon the DC-motor timing,the basic theory and the way to implement. The circuit of rotational speed measuring and setting is presented by four LED. The main-circuit adopts MOSFET three-phases converter. Commutate circuit adopts LM621 to lighten the burden of Single-chip microcomputer. The PWM controller controls the speed.
Key Words Brushless DC Motor, PWM, Measurement of rotating speed, LM621