Research On Speed Sensorless Control System For Permanent Magnet Synchronous Motor Based On Low Frequency Signal Injection

In high-performance permanent magnet synchronous motors (PMSM) AC drives system,the accurate rotor position and velocity are needed to realize field orientation and mechanical sensors are acquired to mount at rotor shaft.But these sensors are expensive, less reliable and not easy to be maintained,the sensorless drive of PMSM has become a hotspot.Most of speed sensorless methods are suitable to motors at middle and high speed.and also have problems at low speed.To solve the problems of low speed,the method of low frequency signal injection to estimate velocity is used in this paper.This method is insenstive to the machine parameters,widely applicability and good robustness.First, presented sensorless control methods are discussed and three basic structures of PMSM are introduced and PMSM mathematical models at different coordinates are builded.Second, fundamental principle of the low frequency signal injection method based on PMSM vector control is discussed to estimate velocity. Simulation models of the PMSM sensorless vector control system are builded in MATLAB/SIMULINK and simulation results demonstrate the validity of low frequency signal injection method.Finally, the low frequency signal injection method is proved successfully on PMSM sensorless vector control based on the DSP chip TMS320F2812 of TI. Experimental results prove that this sensorless control method could realize the low speed operation of machine and has less sensitivity to the variation of machine parameters.