VP12-12: Torque Improvement of E-Core FSPM Motor using Double-Layer Distributed Armature Winding

With the excellent achievement of permanent magnet (PM) materials, PM motors have attracted much attention for decades. Stator PM motor, in which the PMs and armature winding are located on the stator, can achieve simple rotor structure and favorable PM temperature management. Flux switching PM (FSPM) motor is one of the most popular stator PM motors due to the high torque density. This paper proposes a novel double-layer distributed armature winding configuration for 24/22-pole FSPM motor equipped with E-shaped stator iron core [1] so as to obtain a higher torque density. According to the air-gap flux modulation theory, the PM magnetic motive force of 24/22-pole E-core FSPM motors is modulated by the stator and rotor salient pole, generating the air-gap flux density with multiple excitation field harmonics. However, the excitation harmonics of the 24/22-pole E-core FSPM motor share different slot pitch angles, including 60 and 240 degrees. Therefore, when conventional winding design method based on the pole-pair number of armature winding (Pw=Nr-PPM) is applied [2], only the excitation harmonics with the same slot pith angle as that of the harmonic of Pw pole-pair number are considered, leading to the underutilization of the main excitation field harmonics. In this paper, all of the main excitation field harmonics are analyzed to obtain the synthesis coil electromotive force, based on which a novel double-layer distributed winding configuration presented in Fig. 1 can be designed to fully utilize the main excitation field harmonics. Thus, the torque is improved efficiently. The electromagnetic performances of the proposed motor are investigated by finite element analysis. When compared with the conventional winding configuration with the pole-pair number of Pw, the output torque of the proposed scheme can be improved by 15.3% as shown in Fig. 2.References: [1] Y. Mao, Y. Du, F. Xiao, X. Zhu, L. Quan and D. Zhou, “Design and optimization of a pole changing flux switching permanent magnet motor,” IEEE Tran. Ind. Electron., vol. 70, no. 12, pp. 12636-12647, Dec. 2023. [2] Y. Shi, L. Jian, J. Wei, Z. Shao, W. Li and C. C. Chan, “A new perspective on the operating principle of flux-switching permanent-magnet machines,” IEEE Tran. Ind. Electron., vol. 63, no. 3, pp. 1425-1437, Mar. 2016.