Strength Analysis and Design of a Multi-Bridge V-Shaped Rotor for High-Speed Interior Permanent Magnet Synchronous Motors

High-speed operation is a crucial approach for achieving high power density of drive motors for new energy vehicles. However, mechanical strength of the rotor has become the primary bottleneck in the development of high-speed drive motors. Adopting a multi-bridge structure can effectively enhance the mechanical strength of the V-shaped rotors widely used in interior permanent magnet synchronous motors (IPMSMs). Firstly, based on the equivalent centroid principle, the centrifugal forces generated by the rotor’s pole shoes and permanent magnets are calculated. An improved centrifugal force method is proposed to establish an analytical mechanical model of the multi-bridge V-shaped rotor structure. This method comprehensively considers the force conditions, deformation constraints, and material properties of the magnetic bridges. Additionally, stress concentration is taken into account to ensure the accuracy of the model. The effects of various structural parameters on the maximum mechanical stress and deformation are then analyzed. These parameters include the V-angle, pole shoe angle, and the dimensions of three types of magnetic bridges, namely, the central bridge, air-gap bridge, and middle bridge. Finally, recommendations for selecting structural parameters in the mechanical strength design of multi-bridge V-shaped rotors are summarized. The effectiveness of the proposed rotor structure is verified through finite element method and experiments.