The Research Of The Soft Starter For A.C. Asynchronous Motor

To reduce the high starting current as A.C.asynchronous motors start up directly and eliminate the negative influence brought about by switching of contact when it starts up by means of reduced -voltage . The paper introduces a new equipment based on power electronic technology to improve the starting characteristics of A.C.asynchronous motor.This equipment is mainly constituted by C504 and double-action thyristors. The double-loop control system is adopted to make start softly. As start-up electric current changes, the control of the double-loop can be adjusted on real time. It can also monitor the instantaneous current of the system. This paper introduces not only the characteristics and control principle of soft starter, but also hardware circuit ,software design and the system EMC design of soft starter. By experimentation and debugging, we reach performance target of A.C. asynchronous motor start. The A.C.asynchronous motor is started steadily and reliably in the condition of reducing current of A.C. asynchronous motor.