大功率异步电动机新型软起动装置的设计与实现

摘要

In order to reduce the shock of the asynchronous motor start-up on the power grid, to eliminate the impact of traditional voltage dropping trigger with stepped contact on asynchronous motor, and to improve the starting characteristics of asynchronous motor, the soft starting techniques of asynchronous motor have been researched based on the power electronics technology. The soft starting of asynchronous motor is accomplished by using three-phase voltage adjustment to change the triggering angle of the thyristor, and further to adjust the stator voltage. The soft starting device of 50kW asynchronous motor is designed by using double closed-loop three-phase AC voltage regulating circuit. The starting current is automatically adjusted by the PI internal ring current and out ring voltage controls. Not only the starting current is restricted, but also the terminal voltage is increased gradually, thus the smoothly starting of asynchronous motor is realized.%为了减小异步电动机起动过程中对电网的冲击、消除传统降压起动设备的有级触点控制对异步电动机的冲击、改善异步电动机的起动特性，基于电力电子技术对电动机软起动进行了研究。软起动装置是基于三相交流调压技术，通过改变晶闸管的触发角以调节定子两端的电压来实现的。采用双闭环控制的三相交流调压电路设计了50kW异步电动机软起动装置。内环电流控制及外环电压控制采用PI控制，实现了自动调节电动机起动电流，不但限制了电流，又使端电压平稳上升，实现了交流异步电动机平稳软起动。