Hybrid Sensorless Control Based on I/F and Sliding Mode Observer Using Current Nonlinear Regulation for PMSM Drives

Hybrid sensorless control based on current-frequency ratio (I/F) and sliding mode observer has been studied to achieve wide speed range of permanent magnet synchronous motor (PMSM). Most important of all, smoothness of switching process of compound control should be improved. Usually, current linear regulation (CLR) is applied to implement the switching strategy. However, the transition process is long and not smooth. Aiming at this problem, current nonlinear regulation (CNR) is proposed in this paper to linearize the position error changing. Therefore, the transition time is shortened, and speed fluctuation is reduced. The simulation results have proved out the effectiveness of theoretical analysis.