Robust optimization design of low-cost spoke-type permanent magnet motors with auxiliary salient poles

Applying ferrite to spoke-type permanent magnet motors with flux-focusing ability is a low-cost process and can yield torque density comparable to that of rare-earth permanent magnet motors. To overcome the drawback of the high torque ripple associated with traditional spoke-type permanent magnet motors, a new rotor with auxiliary salient poles is proposed. These poles enhance the plasticity of the rotor and increase the number of optimized parameters. The multiobjective optimization method, which combines response surface analysis and multiobjective backbone particle swarm optimization algorithm, is used to improve the torque performance of the motor. The motor will inevitably be affected by uncertainties, such as errors and tolerances, during motor mass production. Therefore, the six sigma design method and Monte Carlo analysis method are combined for optimizing the robustness of the motor. A comparison of the pre- and post-optimization electromagnetic performance revealed that the proposed motor can effectively reduce torque ripple while increasing the output torque and significantly reducing the mass production failure rate of the motor. Finally, experimental results verify the accuracy and feasibility of the proposed new motor structure and its robust optimization design. © 2021, Science Press. All right reserved.