Sensorless control of permanent magnet synchronous motors based on high frequency square wave injection

High-frequency (HF) carrier injection method has become a hot spot in the study of permanent magnet synchronous motor sensor less (PMSM) control technology. However, there are problems such as low precision and large interference in extracting rotor position information by traditional band-pass filter. An improved method is proposed, which is to introduce a second-order generalized integrator (SOGI) into the signal extraction process. It is a filter that can extract or eliminate specific frequency components. Due to its structural characteristics, it has a fast response capability. Therefore, the second-order generalized integrator is employed to acquire the rotor position component, and the position errors is gained by the heterodyne method, Luenberger Observers are employed to estimate velocity and position information. Finally, the superiority and correctness of the improved method are proved by simulation experiments.