Optimization Design of Interior Permanent Magnet Synchronous Motor With U-Shaped Rotor for Low-Level Torque Ripple and Electromagnetic Vibration

The optimization design of the interior permanent magnet synchronous motor (IPMSM) is a challenge due to its complex rotor configuration and interdependent structural parameters. The electromagnetic vibration of the IPMSM is intricate due to the complex contents of electromagnetic force densities caused by the unequal inductances between the
${d}$
- and
${q}$
-axes. In this article, a 6-pole 36-slot IPMSM with a nonuniform air gap is designed, and the multiobjective stratified optimization method is used to optimize the stator and rotor structure parameters for the low-level torque ripple and electromagnetic vibration, which greatly improves the optimization efficiency. In addition, an improved iterative Taguchi method is proposed, the optimization ranges of variables are reasonably narrowed, the optimal structural parameters are found efficiently and accurately, and the superiority of the proposed method is verified by comparing it with the optimization results obtained by the conventional Taguchi method. In addition, the complete analysis of the optimal motor, including losses, temperature distributions, and irreversible demagnetization of the permanent magnets (PMs), is performed, and the rationality of the optimization scheme is comprehensively verified. Finally, sufficient prototype tests are performed, and the prototype test results well verify the feasibility and effectiveness of the proposed optimization method and optimized motor structure.