Due to the advantage of high torque at low speed, permanent magnet vernier (PMV) motor has become an excellent candidate for low-speed direct-drive applications 1, such as electric vehicles. With the increasing critical demand for electric vehicle drives, multiple design requirements have also been proposed for performance of electric vehicle drive motors, including output torque and torque ripple 2. Recently, many researchers have contributed to improving torque performances of PMV, mainly by the design of permanent magnet and stator teeth 3. Yet, it is noted that, current literature on improving motor performances would either increase output torque or reduce torque ripple, while the comprehensive improvement of torque performances can hardly be achieved. Thus, in this paper, an airgap-harmonic-orientated partitioned design method is newly proposed for PMV motors. In the proposed design method, considering the effect of different harmonics on torque performance, the torque designed region of rotor is artfully divided into torque enhanced region and ripple reduced region. And, by the purposeful design of these two regions, output torque is increased while torque ripple is reduced effectively. Fig. 1 shows the configurations of proposed and initial PMV motors. The airgap-harmonic-orientated partitioned design principle is presented in Fig. 2, providing theoretical guidance for motor torque performance improvement. Fig. 3 shows the magnetic field and flux distributions of proposed motor. Meanwhile, based on partition design principle, the airgap flux density waveforms, and the main airgap harmonic variations related to output torque and torque ripple are presented in Fig. 4 and Fig. 5 respectively. It can be seen from Fig. 6 that, by the reasonable design of torque enhanced region and ripple reduced region, output torque of motor is significantly increased by 82.6% while torque ripple is reduced by 61.1% efficiently as expected. Thus, by the proposed airgap-harmonic-orientated partition design method, improved output torque and reduced torque ripple can be realized effectively. The detailed theoretical analysis and simulation results will be presented in the full paper.

References:

1 Y. Ma and W. Fu, IEEE Trans. Magn, vol. 57, no. 6, pp. 1-5, June 2021.
2 B. Lee, Z. Zhu and L. Huang, IEEE Trans. Ind. Appl, vol. 55, no. 3, pp. 2510-2518, May-June 2019.
3 X. Zhu, M. Jiang and Z. Xiang, IEEE Trans. Ind. Electron, vol. 67, no. 7, pp. 5337-5348, July 2020.
4 L. Fang, D. Li and X. Ren, IEEE Trans. Ind. Electron, vol. 69, no. 6, pp. 6058-6068, June 2022.