Design of a Robust Optimal Controller for Five-Phase Permanent Magnet Assisted Synchronous Reluctance Motor in Electric Vehicle Application

This paper presents the design of a robust optimal controller for a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) used in electric vehicle (EV) application. Conventionally, proportional (P) or proportional-integral (PI) controllers are widely used in the speed control system for traction and industrial applications. Simple structure, low-cost, and ease of implementation are key advantages of these controllers. However, these controllers are not robust enough to cope with large system and converter uncertainties. Furthermore, there is a tight trade-off between the speed and the overshoot of the desired system response. To address these issues, in this study, a robust optimal controller using a dual-loop feedback structure is proposed for multiphase PMa-SynRM. The proposed optimal controller is designed using the linear-quadratic-regulator (LQR) technique. Different practical conditions, including system uncertainties, un-modeled dynamics, and external disturbances, are considered to verify the proposed controller’s robustness. Using extensive computer simulations, it is shown that the proposed optimal controller demonstrates higher robustness and design flexibility compared to the conventional controller.