Analysis of End-Effect Torque and Multi-Objective Optimization for Multi-Port Spatial Permanent Magnet Synchronous Motor

Multi-port spatial permanent magnet synchronous motor (MSPMSM) combines the advantages of disk motor and permanent magnet (PM) planetary gear drive, which solves the problem of single output port on traditional PM synchronous motor (PMSM) and realizes multi-port outputs and direct drive. Due to the special structure of disk stator, the planetary gear rotors are affected by end-effect torque in rotation process. The end-effect torque will not only cause torque ripple but also cause vibration and noise. Aiming at the problem of end-effect torque, the generation mechanism of end-effect torque is analyzed. In order to analyze air-gap magnetic field distribution accurately, the arc slotless subdomain (SD) model of planetary gear rotor and disk stator is established in polar coordinate system. The end-effect torque is derived by the Maxwell stress tensor method. Based on Box–Behnken design (BBD) method, a response surface model (RSM) is constructed to reduce end-effect torque amplitude and increase electromagnetic torque. The influences of structural parameters on end-effect torque amplitude are analyzed, and a set of optimal structural parameters are obtained. The end-effect torque and electromagnetic torque of the optimized MSPMSM are analyzed by finite-element analysis method (FEM), and the effectiveness of multi-objective optimization design method is verified. These research results have a good effect on improving the output performance of MSPMSM.