A New Method to Drive Sensorless PMSM Based on SMO Without Switching Step

SMO is now widely used in sensorless permanent magnetic synchronous motors. The problem of motor out of step may happen in switching step and always plays a major role in disturbing running motors. People used to use high-frequency current injected method to get the position information before the sliding mode observer can obtain the real position information. But disadvantages also exist such as the large noise existed when the high-frequency current was injected into the motor and high frequency current also is always with electromagnetic interference. People also used to find and design the switching function to help the motor switch form the current loop to the SMO mode. But most of the functions work only a little. To solve this problem and start the motor from zero speed with SMO's real position information, a new method to run the motor based on sliding mode observer is presented. In this paper, a sensorless field-oriented control (FOC) for permanent magnetic synchronous motor (PMSM) is proposed and an experiment based on DSP TMS320F28377D and a high speed sensorless PMSM is designed to verify the results.