Multi-Objective Optimization for a Low-Speed High-Torque Permanent Magnet Motor

This paper presents a multi-mode optimization method for a spoke-type permanent magnet synchronous (ST -PMS) motor, which is specifically designed for low-speed high-torque applications. In order to achieve the design goals of high torque, low torque ripple, and high efficiency, five typical operating modes are defined according to the practical operating conditions of ST -PMS motors. Objectives are selected separately based on the design requirements of each mode, then clustering analysis and correlation analysis are applied to simplify the optimization procedure. To reduce computational cost, surrogate model is established to replace the finite element method (FEM). Non-dominated sorting genetic algorithm (NSGA2) is employed to search the best solution. Moreover, a novel multi-level optimization method is proposed to achieve higher accuracy and efficiency in comparison to conventional multi-level optimization method.