VP7-05 Torque Ripple Reduction Design Approach of Permanent Magnet Machines Based on Circumferential Pole Pair Shift
Creators: Litao Dai
Shuangxia Niu
Jian Gao and Shoudao Huang
Publisher: name: IEEE
Year: 2025

I. Introduction Electromagnetic torque is the fundamental property of permanent magnet machines (PMMs). Achieving minimal torque ripple is highly desirable for high-performance PMMs. Various methods have been explored to reduce torque ripple in PMMs. However, the existing approaches often come with drawbacks. For instance, some methods result in reduced torque density due to an increased effective airgap volume [1], while others lead to decreased winding utilization [2]. Moreover, the associated rise in manufacturing costs poses a significant concern. To overcome these limitations, this paper proposes a novel method for suppressing torque ripple in PMMs. The approach proposes a circumferential shift strategy of the rotor pole-pair, accompanied by two shifting approaches. II. Verification This paper presents two design paths, namely reverse shifting and gradual shifting of pole pairs, for reducing torque ripple in PMMs. Fig. 1 illustrates these design paths, while Fig. 2 showcases the torque waveforms over one electrical cycle obtained of a motor case study under both shifting methods. Notably, the results show a significant reduction in torque ripple, with method-1 achieving a reduction from 30.26% to 4.82% and method-2 achieving a reduction to 1.93%. These findings demonstrate the effectiveness of the two approaches in suppressing torque ripple to varying degrees. Furthermore, it is essential to highlight that implementing these methods does not result in additional manufacturing costs.References: [1] Y. Yokoi and T. Higuchi, "Stator Design of Alternate Slot Winding for Reducing Torque Pulsation With Magnet Designs in Surface-Mounted Permanent Magnet Motors," IEEE Transactions on Magnetics, vol. 51, no. 6, pp. 1-11, June 2015, Art no. 8202911. [2] M. S. Islam, R. Mikail, M. A. Kabir and I. Husain, "Torque Ripple and Radial Force Minimization of Fractional-Slot Permanent Magnet Machines Through Stator Harmonic Elimination," IEEE Transactions on Transportation Electrification, vol. 8, no. 1, pp. 1072-1084, March 2022.
I. Introduction Electromagnetic torque is the fundamental property of permanent magnet machines (PMMs). Achieving minimal torque ripple is highly desirable for high-performance PMMs. Various methods have been explored to reduce torque ripple in PMMs. However, the existing approaches often come with drawbacks. For instance, some methods result in reduced torque density due to an increased effective airgap volume [1], while others lead to decreased winding utilization [2]. Moreover, the associated rise in manufacturing costs poses a significant concern. To overcome these limitations, this paper proposes a novel method for suppressing torque ripple in PMMs. The approach proposes a circumferential shift strategy of the rotor pole-pair, accompanied by two shifting approaches. II. Verification This paper presents two design paths, namely reverse shifting and gradual shifting of pole pairs, for reducing torque ripple in PMMs. Fig. 1 illustrates these design paths, while Fig. 2 showcases the torque waveforms over one electrical cycle obtained of a motor case study under both shifting methods. Notably, the results show a significant reduction in torque ripple, with method-1 achieving a reduction from 30.26% to 4.82% and method-2 achieving a reduction to 1.93%. These findings demonstrate the effectiveness of the two approaches in suppressing torque ripple to varying degrees. Furthermore, it is essential to highlight that implementing these methods does not result in additional manufacturing costs.References: [1] Y. Yokoi and T. Higuchi, "Stator Design of Alternate Slot Winding for Reducing Torque Pulsation With Magnet Designs in Surface-Mounted Permanent Magnet Motors," IEEE Transactions on Magnetics, vol. 51, no. 6, pp. 1-11, June 2015, Art no. 8202911. [2] M. S. Islam, R. Mikail, M. A. Kabir and I. Husain, "Torque Ripple and Radial Force Minimization of Fractional-Slot Permanent Magnet Machines Through Stator Harmonic Elimination," IEEE Transactions on Transportation Electrification, vol. 8, no. 1, pp. 1072-1084, March 2022.