Electromagnetic Vibration Improvement for a High-Speed Flat Wire PM Motor Based on Optimal Magnetic-Pole Boundary

In this article, a high-speed flat wire permanent magnet (PM) motor is proposed for the potential application of electric vehicles (EVs), where the radial force and torque ripple are investigated for achieving low vibration design. The key of this study is to incorporate a concept of magnetic-pole boundary into the motor design, aiming at realizing vibration suppression under active structural strength constraints. By establishing the relationships among radial force, torque ripple, and airgap flux density, the corresponding dominant harmonics are determined and further functioned as optimization objectives. Meanwhile, the centrifugal force model of the magnetic pole is established for calculating its maximum mechanical stress (MMS). Then, the MMS of the magnetic pole is purposely considered as the design constraint. Subsequently, a multiobjective optimization considering magnetic-pole boundary is conducted and investigated. The electromagnetic vibration and mechanical stress characteristics of the motor are analyzed in detail. The analysis results verify that the vibration and mechanical stress are simultaneously improved by the design of optimal magnetic-pole boundary.