Multi-Variable Structure Optimization for Cogging Torque and Torque Ripple Reduction in High-Speed Permanent-Magnet Motor with Dual-Phase Magnetic Materials

The rotor of the high-speed sleeveless interior permanent magnet synchronous motor (IPMSM) with dual-phase magnetic materials integrates high mechanical strength and low saturation flux density materials, which enhances rotor structural strength and effectively suppresses permanent magnet flux leakage to achieve torque density improvement. However, the magnetic barrier effect in the flux bridge region exacerbates airgap magnetic field distortion, leading to intensified cogging torque and torque ripple. To address this issue, this paper employs a multi-variable structural collaborative optimization method. Based on a finite element analysis (FEA) method, three suppression strategies - stator auxiliary slotting, stator tooth top offset, and rotor inverse-cosine shaping - and their electromagnetic coupling mechanisms are systematically investigated. The results indicate that the collaborative scheme of inverse-cosine shaping combined with stator tooth top offset can effectively reduce the cogging torque and torque ripple of the motor.