New Rotor Topology and Electromagnetic Performance Optimization of High-speed Permanent Magnet Synchronous Motors

The traction motors of electric vehicles primarily employ interior permanent magnet synchronous motors (IPMSMs). IPMSMs utilize ribs and bridges to prevent the permanent magnets from separating due to centrifugal force during motor rotation. Increasing the thickness of the ribs and bridges enhances rigidity at high speeds, but this leads to increased leakage flux, thereby degrading motor performance. In this paper, to improve the performance of IPMSMs, a novel rotor topology is designed for a 60 kW, 10,000 r/min interior high-speed permanent magnet synchronous motor. This structure eliminates the magnetic isolation bridges that cause leakage flux and employs carbon fiber retaining sleeves to enhance rotor mechanical strength. This design increases torque and improves efficiency but also raises torque ripple. To address this, an uneven pole structure is proposed, optimizing the rotor topology to minimize torque ripple effects while increasing motor torque and reducing rotor core losses. Additionally, electromagnetic performance under different conditions is compared, providing a reference for the design of high-speed permanent magnet synchronous motors.