Enhancing Electromagnetic Performance of Traction PMaSynRMs With Asymmetrical Rotor Configurations

The alignment of permanent magnet (PM) and reluctance torques considering their space harmonic impacts is crucial for maximizing torque generation while minimizing torque ripple and cogging torque in permanent magnet-assisted synchronous reluctance machines (PMaSynRMs) designed for electric vehicles, all while minimizing the reliance on heavy rare-earth magnets (HRePMs). Therefore, this paper introduces PMaSynRMs with reduced HRePMs and asymmetric rotor configurations to achieve these electromagnetic performances. Three main approaches, namely (a) PM placement, (b) flux barrier design, and (c) combined PM and rotor flux barrier designs are employed to introduce asymmetries based on the single pole of the machine and to improve the net torque through enhancing the PM torque utilization. The design featuring combined asymmetric PMs and flux barriers strikes a balance, providing 4% higher torque, 8.5% reduction in torque ripple, and similar cogging torque levels, all while reducing electromagnetic losses by 2.84% compared to the baseline PMaSynRM.