Modeling and Experimental Validation of Flow-Thermal-Coupled Lumped-Parameter Network for Axial-Flux Permanent-Magnet Motor With Oil-Immersed Cooling System

With the increase of electrical load, the temperature rise in axial flux permanent magnet (AFPM) motor is gradually prominent. Excessive temperature rise directly affects the stable operation of the motor and limits its performance improvement. This article proposes an efficient immersion cooling system for high-torque AFPM motor. Comprehensively considering the cooling oil flow characteristics, oil baffle plates are installed between the end windings and the shell, which improve the cooling oil coverage and enhance the stator heat dissipation capability. Furthermore, flow channels are integrated in the sealing plate, reinforcing the cooling of winding regions with high eddy current losses. Based on computational fluid dynamics (CFD), the thermal analysis of the AFPM motor is carried out. The results show that compared to the conventional oil-immersed cooling structure, the stator core temperature decreases from 67°C to 52°C, and the winding temperature declines from 85°C to 63°C. Then, the flow network and thermal network are constructed and coupled iteratively to investigate the effect of key parameters on motor thermal performance. Finally, a 850 N·m AFPM motor is manufactured and tested. The experimental data for temperature rise are in good agreement with the proposed calculation method, with a deviation of within 5%.