A Sensorless Starting Method for Self-Controlled Synchronous Motors

摘要

Self-controlled synchronous motors have been used as variable speed motors in industry and are now also used for propelling ships. In this type of motor, information on the rotor position is needed in order to achieve stable operation. A simple sensorless starting method for this motor is studied in this paper. An initial rotor position detection method without a position sensor is first discussed. It is shown that the position can be detected easily by observing the electromotive forces induced in the armature windings due to the change in the field current. Then, a new starting method for the motor is proposed on the basis of DC link current chopping during the starting period. It is shown that, based on the proposed method, starting of the motor can be realized independently of the load conditions, which indicates the usefulness of the proposed method. Finally, the effects of various system parameters on the response of the DC input current and the motor speed during starting up are discussed.