Analytical Calculation of Magnetic Field of Permanent Magnet Synchronous Motor with Uneven Air Gap Structure
Zhao Shihao1,2, Chen Jinhua2, Zhang Chi2, Li Zheng1, Meng Yulong1,2
1. School of Electrical Engineering Hebei University of Science and Technique Shijiazhuang 050018 China; 2. Laboratory of Robotics and Intelligent Manufacturing Equipment Technology of Zhejiang Province Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China
Abstract In order to achieve sinusoidal back EMF and low torque ripple in the design process of permanent magnet motor for industrial robot and numerical control machine, the uneven air gap structure of bread-shaped or eccentric pole cutting is often used. Based on the differential principle, the rotor pole of the non-uniform air gap structure was divided into four subdomains: permanent magnet, air gap, slot opening and stator slot, and the Poisson equation and Laplace equation were established. The partial differential equation was solved by the variable separation method and the Fourier series method. The harmonic coefficients of each subdomain were solved by the boundary conditions to obtain the magnetic field distribution of each segmented pole, and then the two-dimensional magnetic field distribution of the electric machine was obtained by the equivalent superposition based on the integral principle. The analytical method also takes into account the pole rotor structure of tile type, eccentric type and bread type, and can calculate the no-load, armature and load magnetic field characteristics of the motor with any number of units. Accordingly, the torque and no-load back EMF characteristics can be calculated. The analytical method is verified by the comparison of the prototype test results, the finite element simulation results and the analytical results, which can quickly guide the motor design.
Zhao Shihao,Chen Jinhua,Zhang Chi等. Analytical Calculation of Magnetic Field of Permanent Magnet Synchronous Motor with Uneven Air Gap Structure[J]. Transactions of China Electrotechnical Society, 2022, 37(14): 3502-3513.
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2022, Vol. 37 
