Model-Based Sensorless Control of an IPMSM With Enhanced Robustness Against Load Disturbances Based on Position and Speed Estimator Using a Speed Error

In this paper, new model-based sensorless control methods are proposed that include independent estimations of position and speed errors, and compatible position and speed estimators. Using the proposed position estimator, a unity transfer function can be achieved from the actual position to the estimated position, eliminating the effects of load disturbances. This implies that the position error would ideally be zero, even in a transient state. In addition, the effects of parameter and voltage synthesis errors on the steady-state position error are analyzed. Experimental results verify both the analysis and the effectiveness of the proposed methods under severe load disturbances such as speed transient (20 000 r/min/s) and load torque transient (10 p.u./s). With the proposed methods, position estimation errors are significantly reduced by more than 50% during speed and load torque transients at identical dominant-pole placements, verifying the enhanced tracking capability and robustness of the proposed methods against external load disturbances.