The Development Of The Energy-Saving Soft Starter For Asynchronous Motor Using DSP

The three-phase asynchronous motors are nowadays widely used in all types of industry applications due to their simple construction, high reliability and low price. However, the direct start of asynchronous motor can generate much high current, which will contaminate the power grid and injure the motor. Furthermore, when an asynchronous motor runs on light loading, the efficiency and power factor both greatly reduce. In order to improve the starting characteristics and efficiency of the motor, a three-phase asynchronous motor energy-saving soft starter is developed using DSP-TMS320F2808. The main contributions are made as followings:Conventional methods of motor soft stating and energy saving are analyzed. The principle of three-phase AC voltage regulating circuit by thyristor and energy saving is presented. The control methods of ramp voltage starting, current-limiting starting and ramp voltage-current-limiting staring of combining the current feedback and PID are discussed. A control method of combining the current feedback and load tracking controller is presented.A model of asynchronous motor soft starting is provided based on MATLAB/Simulink. Moreover, the simulation experiments of motor were carried out. The results show the three-phase AC voltage regulating can be achieved by thyristor and proposed method can control the motor stating current effectively.Base on above analysis, the hardware and software design of the control system using TMS320F2808 chip is provided. Motor test results show using the proposed system the motor soft-started successfully, and the starting current was effectively controlled. Furthermore, energy saving was realized when the motor running on light loading...