Observer-based Robust Control: Its Application to Permanent Magnet Synchronous Motors

This paper presents an observer-based robust control for mechatronic systems that utilize a surface-mounted perma-nent magnet synchronous motor (SPMSM). A mechatronics system with an SPMSM typically comprises a mechanical moving part (outer-loop) and a power converter (inner-loop) to drive the motor. We explain the dynamic modeling of the SPMSM and provide a brief discussion on disturbances in the SPMSM. A cascaded tracking error dynam-ics of the SPMSM is derived by using a speed controller and torque modulation to analyze disturbances present in outer-loop and inner-loop systems. This cascaded structure highlights how the disturbances in the mechanical moving parts (outer-loop) and power converter (inner-loop) hinder the motion-tracking performance of the SPMSM. This paper demonstrates how the cascaded structure facilitates the stability analysis of the closed-loop system and the design of feedback controllers. The paper aims to help readers understand intrinsic problems in motion control of a mechatronic system driven by the SPMSM and how to design an observer-based robust control of the SPMSM.