Model-based Sensorless Control of IPMSM Enhancing Robustness based on the Estimation of Speed Error

In this paper, new model-based sensorless control methods are proposed, including estimation methods for the position and speed errors and compatible position and speed estimators. In proposed methods, the speed error is estimated as well as the position error in the conventional model-based sensorless methods. By the proposed methods, unity transfer function from actual position to estimated position can be achieved eliminating the effects of load disturbances. It means that the position error would be ideally zero even in transient situations. Experimental results verify the effectiveness of the proposed methods under severe speed transient (20,000 r/min/s) and load torque transient (20 p.u./s). With the proposed methods, position error has been conspicuously reduced by 60% at speed transient and by 70% at load torque transient in high speed region.