VP5-06 An Interior Permanent Magnet Synchronous Machine with Asymmetric Structure for Improving Torque Density
Creators: Xiaoyu Liang
Mingqiao Wang*
Yong Liu*
Ping Zheng and Wanquan Li
Publisher: name: IEEE
Year: 2025

Permanent magnets (PMs) and armature windings generate electromagnetic fields with different harmonic characteristics and spatial distribution in permanent magnet synchronous machine (PMSM). With the needs of industry development, more and more design and combination methods of them are being adopted to improve the efficiency of energy conversion and energy density in PMSM. In conventional interior PMSM (IPMSM), the reluctance torque (TR) and PM torque (TP) cannot reach the maximum at the same time (current angle), limiting the above performance. The design based on magnetic-field-shifting (MFS) can place the PM and armature magnetic field in a specific spatial angle relationship in the IPMSM according to their characteristics. Based on this, the current angle difference of the peak of TR and TP can be reduced, and thus the electromagnetic torque (TE) can be increased to improve the efficiency of energy conversion [1, 2]. Although this method achieves the improvement of TE, the asymmetric structure adopted by this process may have a negative impact on each magnetic field and torque component. The study of IPMSM topology helps to reduce the negative effects and achieve better MFS. The effect and principle of MFS machine are shown in Fig. 1. Through a specific asymmetric structure, the angle between the two torque components (TR and TP) is reduced to improve the combined torque (TE) significantly by theoretical analysis. It can be seen that MFS causes changes in physical quantities such as current in d- /q-axis coordinates in the phasor diagram. The torque characteristics of the conventional and proposed machine with asymmetric structure are shown in Fig. 2. The proposed machine achieves the torque-current angle characteristics in the theoretical analysis. The torque output and overload capacity of the proposed are improved. By studying the topology of the MFS IPMSM, the torque density and torque characteristics can be improved to increase the energy conversion efficiency.References: [1] Z. Q. Zhu and Y. Xiao, "Novel Magnetic-Field-Shifting Techniques in Asymmetric Rotor Pole Interior PM Machines With Enhanced Torque Density," IEEE Transactions on Magnetics, vol. 58, no. 2: 8100610 (2022) [2] X. Zhu, Sipeng Li, and Shiyue Zheng, "Torque Component Redistribution and Enhancement for Hybrid Permanent Magnet Motor With Permanent Magnet Offset Placement," IEEE Transactions on Transportation Electrification, vol. 9, no. 1, pp. 631-641 (2023)
Permanent magnets (PMs) and armature windings generate electromagnetic fields with different harmonic characteristics and spatial distribution in permanent magnet synchronous machine (PMSM). With the needs of industry development, more and more design and combination methods of them are being adopted to improve the efficiency of energy conversion and energy density in PMSM. In conventional interior PMSM (IPMSM), the reluctance torque (TR) and PM torque (TP) cannot reach the maximum at the same time (current angle), limiting the above performance. The design based on magnetic-field-shifting (MFS) can place the PM and armature magnetic field in a specific spatial angle relationship in the IPMSM according to their characteristics. Based on this, the current angle difference of the peak of TR and TP can be reduced, and thus the electromagnetic torque (TE) can be increased to improve the efficiency of energy conversion [1, 2]. Although this method achieves the improvement of TE, the asymmetric structure adopted by this process may have a negative impact on each magnetic field and torque component. The study of IPMSM topology helps to reduce the negative effects and achieve better MFS. The effect and principle of MFS machine are shown in Fig. 1. Through a specific asymmetric structure, the angle between the two torque components (TR and TP) is reduced to improve the combined torque (TE) significantly by theoretical analysis. It can be seen that MFS causes changes in physical quantities such as current in d- /q-axis coordinates in the phasor diagram. The torque characteristics of the conventional and proposed machine with asymmetric structure are shown in Fig. 2. The proposed machine achieves the torque-current angle characteristics in the theoretical analysis. The torque output and overload capacity of the proposed are improved. By studying the topology of the MFS IPMSM, the torque density and torque characteristics can be improved to increase the energy conversion efficiency.References: [1] Z. Q. Zhu and Y. Xiao, "Novel Magnetic-Field-Shifting Techniques in Asymmetric Rotor Pole Interior PM Machines With Enhanced Torque Density," IEEE Transactions on Magnetics, vol. 58, no. 2: 8100610 (2022) [2] X. Zhu, Sipeng Li, and Shiyue Zheng, "Torque Component Redistribution and Enhancement for Hybrid Permanent Magnet Motor With Permanent Magnet Offset Placement," IEEE Transactions on Transportation Electrification, vol. 9, no. 1, pp. 631-641 (2023)