VP6-08 Analytical analysis and experimental verification of electromagnetic performance of slotless permanent magnet brushless motor
Creators: Jiangtao Yang
Hongjie Li
Zhenyu Wang
Chuang Gao
Xiaojie Zhuang
and Shoudao Huang
Publisher: name: IEEE
Year: 2025

This paper introduces an analytical approach for assessing the electromagnetic performance of sectoral windings in slotless permanent magnet brushless motors. Initially, the methodology involves the electromagnetic torque of a single coil, which is subsequently analyzed in a categorical manner, yielding analytical expressions that capture the electromagnetic performance for scenarios where p≠2, as well as the specific case of p=2. Subsequently, to validate the practicality of this analytical method, finite element simulations and analytical computations are conducted on a range of sectoral winding motors, encompassing diverse pole-slot configurations. Ultimately, a prototype of a 6-slot 4-pole motor is fabricated, serving as a testbed to verify the precision of the proposed analytical framework. While the electromagnetic parameters of slotless permanent magnet motors have been analyzed in [2], it does not take into account the specific case of p = 2. In light of this, this paper proposes a more comprehensive analytical model to derive more precise analytical results. From the Fig. 1 equation, it is evident that a discrepancy arises in the fundamental analytical formula of the slotless permanent magnet motor when the number of pole pairs is different (p ≠ 1). Specifically, there is a distinction between the cases where the number of pole pairs is equal to two (p = 2) and when it is not (p ≠ 2). In the particular instance where p is specifically equal to 2, a separate calculation is required. A comparative analysis is undertaken between the specific instance of P = 2 and the broader case of P ≠ 2, utilizing finite elements and analytical methods accordingly. Fig. 2(a)(b) presents the torque comparison outcomes for 6S2P and 6S4P brushless motors. Notably, the deviation between these two methodologies is negligible, thus preliminarily validating the accuracy of the analytical approach. To validate the accuracy of this analytical method, a 6-slot 4-pole motor, as shown in Fig. 2(c), has been designed and tested through rigorous experimental procedures.References: [1] Yang J, Dai S, Wang Z, et al. IEEE Transactions on Transportation Electrification, 2023: 1–1. Doi: 10.1109/TTE. 2023.3306458 [2] Min S G, Sarlioglu B. IEEE Transactions on Transportation Electrification, 2018, 4(2): 517–524. [3] Z. Q. Zhu, D. Howe, and C. C. Chan, IEEE Trans. Magn., vol. 38, no. 1, pp. 229–238, Jan. 2002. [4] Markovic M, Perriard Y. IEEE Transactions on Magnetics, 2006, 42(12): 3842–3846.
This paper introduces an analytical approach for assessing the electromagnetic performance of sectoral windings in slotless permanent magnet brushless motors. Initially, the methodology involves the electromagnetic torque of a single coil, which is subsequently analyzed in a categorical manner, yielding analytical expressions that capture the electromagnetic performance for scenarios where p≠2, as well as the specific case of p=2. Subsequently, to validate the practicality of this analytical method, finite element simulations and analytical computations are conducted on a range of sectoral winding motors, encompassing diverse pole-slot configurations. Ultimately, a prototype of a 6-slot 4-pole motor is fabricated, serving as a testbed to verify the precision of the proposed analytical framework. While the electromagnetic parameters of slotless permanent magnet motors have been analyzed in [2], it does not take into account the specific case of p = 2. In light of this, this paper proposes a more comprehensive analytical model to derive more precise analytical results. From the Fig. 1 equation, it is evident that a discrepancy arises in the fundamental analytical formula of the slotless permanent magnet motor when the number of pole pairs is different (p ≠ 1). Specifically, there is a distinction between the cases where the number of pole pairs is equal to two (p = 2) and when it is not (p ≠ 2). In the particular instance where p is specifically equal to 2, a separate calculation is required. A comparative analysis is undertaken between the specific instance of P = 2 and the broader case of P ≠ 2, utilizing finite elements and analytical methods accordingly. Fig. 2(a)(b) presents the torque comparison outcomes for 6S2P and 6S4P brushless motors. Notably, the deviation between these two methodologies is negligible, thus preliminarily validating the accuracy of the analytical approach. To validate the accuracy of this analytical method, a 6-slot 4-pole motor, as shown in Fig. 2(c), has been designed and tested through rigorous experimental procedures.References: [1] Yang J, Dai S, Wang Z, et al. IEEE Transactions on Transportation Electrification, 2023: 1–1. Doi: 10.1109/TTE. 2023.3306458 [2] Min S G, Sarlioglu B. IEEE Transactions on Transportation Electrification, 2018, 4(2): 517–524. [3] Z. Q. Zhu, D. Howe, and C. C. Chan, IEEE Trans. Magn., vol. 38, no. 1, pp. 229–238, Jan. 2002. [4] Markovic M, Perriard Y. IEEE Transactions on Magnetics, 2006, 42(12): 3842–3846.