device for the excitation of a synchronous motor with asynchronous demarrant

摘要

An arrangement for exciting the rotating field winding of a synchronous motor includes an alternating current exciter whose armature is mounted on the motor shaft and delivers direct current to the field winding by means of a main rectifier bridge circuit also mounted on the motor shaft. The negative half of the rectifier bridge consists of controllable semiconductor elements and the positive half of non-controllable type semiconductor elements. The controllable semiconductor elements in the bridge perform in a normal manner during synchronous operation of the motor but means in the form of an auxiliary rectifier arrangement are provided to render them non-conductive during asynchronous starting thus to cut off current flow from the output of the main rectifier bridge to the field winding of the motor.