Analytical Modeling for Rotor Eddy Current Loss of High-Speed Surface-Mounted Permanent Magnet Motor with Double-Layer Compound Retaining Sleeve
Tong Wenming1, Tian Ye1, Li Xiaojian1, Jia Jianguo1, Li Wendong2
1. National Engineering Research Center for Rare-Earth Permanent Magnet Motor Shenyang University of Technology Shenyang 110870 China; 2. Shenyang Micro Control New Energy Technology Co. Ltd Shenyang 110178 China
Abstract:High-speed permanent magnet motors (HSPMM) are widely used in high-speed machine tools, flywheel energy storage, and other fields due to their small size and high power density. For surface-mounted HSPMM, the rotor eddy current loss is large, and the heat dissipation conditions are poor, which may cause the rotor temperature to rise too high and increase the irreversible demagnetization risk of the permanent magnet. The double-layer composite retaining sleeve can effectively suppress the eddy current loss of the rotor, and the finite element method is mainly used to calculate its eddy current loss. This method needs a long calculation time. Therefore, based on the exact subdomain method, this paper proposes a general analytical model for rotor eddy current loss of double-layer composite retaining sleeve HSPMM considering stator slotting and eddy current reaction. Firstly, the whole field of the motor is divided into six sub-domains, such as permanent magnet, retaining sleeve, and air gap. The analytical model for rotor eddy current loss of HSPMM is established. Through the boundary conditions between each subdomain, the general expression of the magnetic field distribution in each subdomain is obtained. Then, the equations are solved by constructing the unknown coefficient equations, and the eddy current loss of each part of the rotor is calculated. Secondly, the air gap flux density and rotor eddy current loss of the selected prototype are calculated using finite element and analytical methods. The results show that the analytical method is almost consistent with the finite element method, and the double-layer composite retaining sleeve significantly suppresses the rotor eddy current loss of the surface-mounted HSPMM. The influence of different retaining sleeve thickness ratios and retaining sleeve materials on the eddy current loss is studied by the analytical model, and eddy current loss variations under different rotor structures are obtained. Finally, the C-type core experiment is established, and the calculation results of the eddy current loss analytical method are compared with the experimental results of the C-type core. The following conclusions are drawn through analytical calculation and experimental results. The error between the analytical calculation and experimental results is within 5%, and the model has high calculation accuracy. The double-layer composite retaining sleeve with outer carbon fiber and inner alloy effectively suppresses the eddy current loss of the rotor. When the thickness of the outer carbon fiber retaining sleeve is 1/3~1/2 of the total thickness of the double-layer composite retaining sleeve, the rotor eddy current loss suppression effect is the best. Taking the motor in this paper as an example, the double-layer composite retaining sleeve reduces the eddy current loss of the rotor by about 67.2% and 23%, respectively, compared with the single-layer nickel-based alloy and single-layer carbon fiber retaining sleeve. Moreover, the larger conductivity of the inner alloy retaining sleeve has a smaller total eddy current loss of the rotor.
佟文明, 田野, 李晓健, 贾建国, 李文东. 双层复合护套高速永磁电机转子涡流损耗解析模型[J]. 电工技术学报, 2024, 39(14): 4328-4340.
Tong Wenming, Tian Ye, Li Xiaojian, Jia Jianguo, Li Wendong. Analytical Modeling for Rotor Eddy Current Loss of High-Speed Surface-Mounted Permanent Magnet Motor with Double-Layer Compound Retaining Sleeve. Transactions of China Electrotechnical Society, 2024, 39(14): 4328-4340.
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