A sensorless starting method for self-controlled synchronous motors without damper windings using a DC chopper in the exciter circuit

A sensorless starting method for self-controlled synchronous motors without damper windings is proposed. The proposed method is based on the fact that electromotive forces induced in the armature windings due to the change in field current depend on the rotor position of the motor, and a DC chopper circuit is used in the exciter field circuit to detect the rotor position. The usefulness of the proposed position detecting method without any sensor is demonstrated by experimental investigations.