Rotor Air-Friction Loss and Thermal Analysis of IPM Rotors for High Speed Axial-Flux Machine

This paper focuses on the temperature rise of high-speed disc rotor considering the air-friction loss for an axial flux permanent magnet (AFPM) motor with double rotors and sandwiched stator. The air-friction loss and the heat transfer coefficient on the rotor surface at different speed are obtained based on the formula method and Fluid-Thermal coupling analysis. The rotor temperature distribution based on the coupling analysis of temperature and fluid field is obtained considering various losses and the impact of heat dissipation of air flowing in the motor cavity. Finally, the temperature variation of rotor disc considering the rotating speed is presented for the AFPM motor in this paper. The heat dissipation mechanism of rotor disc for the AFPM motor are revealed. It provides a significant guideline for the cooling design and the efficiency enhancement of high speed AFPM motor.