Analytical Calculation and Analysis of Torque for Brushless DC Motors with Halbach Magnet Array
Luo Ling1, Xue Likun1, Wu Xianyu2, Zhang Leyue1
1. School of Automation Northwestern Polytechnical University Xi'an 710072 China; 2. College of Aerospace Science and Engineering National University of Defense Technology Changsha 410073 China
Abstract：Since the Halbach magnet array offers self-shielding magnetization and can easily change the waveform of air gap flux density, in this paper it is used in brushless DC motors to increase the electromagnetic torque and reduce the cogging torque. The model for calculating electromagnetic torque and cogging torque is presented according to the no-load magnetic field and the armature magnetic field calculated by conform transformation. Then, the calculated electromagnetic torque and cogging torque are compared with those calculated by the finite-element method (FEM). For the brushless DC motors with Halbach magnet array, the electromagnetic torque and the cogging torque are analyzed when the arc angle of the main segment of two permanent magnets in one pole is different, and they are also calculated when the arc angle of the main segment and the magnetizing angle of lateral permanent magnet (PM) of three PMs in one pole are changed. Furthermore, when the thickness of the PM is changed, the electromagnetic torque and the cogging torque in the brushless DC motor with Halbach magnet array are compared with those in the brushless DC motor with radial magnetization and parallel magnetization. The results show that, if the arc angle of main segment and the magnetizing angle of lateral PM in the Halbach magnet array are properly chosen, the electromagnetic torque can increase and the cogging torque can decrease. As the PM thickness increases, Halbach permanent magnet array is more conducive to increase the electromagnetic torque.
罗玲, 薛利昆, 吴先宇, 张乐玥. Halbach永磁阵列无刷直流电机转矩的解析计算和分析[J]. 电工技术学报, 2017, 32(16): 124-135.
Luo Ling, Xue Likun, Wu Xianyu, Zhang Leyue. Analytical Calculation and Analysis of Torque for Brushless DC Motors with Halbach Magnet Array. Transactions of China Electrotechnical Society, 2017, 32(16): 124-135.
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2017, Vol. 32 
