Research of Sensorless Control Method for PMSM Based on Specific Voltage Feed-forward Decoupling

The sensorless control of permanent magnet synchronous motor (PMSM) has issues of complex signal process, cumbersome system structure and parameter setting, etc. To eliminate these defects and reduce costs of computation, a sensorless control method based on specific voltage feed-forward decoupling (VFD) is proposed for the medium and high-speed regions. On the one hand, the proposed method utilizes a specific feed-forward voltage to decouple the d-q axis current, so that the output of current regulator directly contains the position error signal and rotor magnetic flux information, which simplifies the signal processing. On the other hand, the normalization of position error signal eliminates the influence of rotor speed and magnetic flux on the loop feed-forward gain of position estimation. With the proposed method, the rotor position and the rotor magnetic flux can be observed simultaneously and the process of parameter setting can be simplified. Moreover, to meet the engineering requirements, a full-speed sensorless control scheme combines IF control starting strategy with VFD is designed in this paper. The experimental results show that the sensorless method for the medium and high speed proposed in this paper has good dynamic and static performance, the observed result of rotor magnetic flux is accurate, and the designed sensorless control scheme for the full-speed region is simple and practical.