Study on axial segment strength and dynamics of high speed permanent magnet motor rotor

Aiming at strength and dynamics issues caused by the axial segmentation design of sheaths and permanent magnets, a high-speed permanent magnet motor with rated power of 150 kW and rated speed of 30 000 r / min was taken as the research object. Based on the thick wall cylinder theory, a strength simulation model was established. The distribution law of the rotor stress of the sheath axial segmented structure and the influence law of the number of sheath segments on the rotor strength were studied by analytical method and finite element method. Rationality of the law is verified by the thick wall cylinder theory. The dynamic simulation model of rotor system was established, and the influence of the number of permanent magnet and sheath segments on the critical speed and unbalance response was studied by finite element method. The results show that the axial segmentation of the sheath increases the local maximum axial stress and tangential stress of the permanent magnet. The axial segmentation of the permanent magnet reduces the critical speed of each stage of the rotor, especially for the rotor with high rigidity, and increases the rotor amplitude. It provides strength and dynamics reference for the design of high-speed permanent magnet motor sheath and permanent magnet axial segment. © 2023 Editorial Department of Electric Machines and Control. All rights reserved.