Design of current-risk-aware disturbance rejection controller for speed regulation of PMSMs

This paper presents a current-risk-aware disturbance rejection controller (CRA-DRC) for speed regulation of permanent magnet synchronous motors (PMSMs), enhancing their reliability and safety. The CRA-DRC considers a current-risk-aware constraint, which reduces the conservatism associated with hard current-constraint and expands the feasible region of operation. To estimate unmatched disturbances (external load torques), a disturbance observer (DOB) is designed and implemented. However, the non-convex nature due to this current-risk-aware constraint poses a significant challenge for the resulting optimization problem. To address this issue, a distributionally robust reformulated method is proposed, which approximates the speed regulation problem as a second-order cone optimization problem. This approach enables simultaneous online computation of optimal control input and feedback gain while ensuring compliance with current safety specifications. It shows promising potential as a formal control solution for achieving safe and reliable motion control of PMSMs. Simulation and experimental results validate the effectiveness of the proposed approach, demonstrating precise speed tracking with fast dynamic response even in the presence of disturbances and noise. Furthermore, the proposed method is compared to other commonly used control methods like the current-constrained disturbance rejection controller and disturbance rejection model predictive control, further establishing its superiority.