Multi-Objective Optimization Design of a Multi-Permanent-Magnet Motor Considering Magnet Characteristic Variation Effects

In this article, a parallel-series magnetic circuit multi-permanent magnet (M-PM) motor is designed and optimized considering magnet characteristic variation effects, where two kinds of permanent magnets (PMs) are utilized as co-magnetic. Based on the equivalent magnetic circuit method, the detailed design method for the M-PM motor is illustrated. Considering the various operation conditions in potential electric vehicle applications, the B–H curves of two PMs of different typical operation conditions are obtained. Then, a multiobjective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect but also considers output torque, torque ripple as well as antidemagnetization capability under three typical operation conditions. The performances of the initial motor and optimal motor are compared under typical operation conditions. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the motor and the proposed design optimization method.