Cooling Optimization and Analysis of Air-cooled Axial Flux Permanent Magnet Motors Based on Direct Heat Dissipation with Auxiliary Heat Pipes

The propeller electric drive system puts forward strict requirements on the volume limit and torque density of the drive motor, and the small installation volume and high power density of the drive motor will cause the heat can not be effectively dissipated during operation. Therefore, this paper proposes an air-cooled axial flux permanent magnet (AFPM) motor based on direct heat dissipation with auxiliary heat pipes, in an attempt to provide an efficient cooling method in the windings of single-stator dual-rotors AFPM motors with flat stator structure. The evaporation end of the heat pipe with high thermal conductivity is inserted into the stator slot to provide an auxiliary cooling path for the winding and the stator core. The condensation end of the heat pipe is connected to an aluminum radiator to increase the area of convective heat transfer. Firstly, the electromagnetic topology of AFPM motor is introduced, and the electromagnetic properties of different stator core materials are compared. Secondly, based on the computational fluid dynamics (CFD) model, the influence of heat pipe thermal conductivity and radiator size on temperature rise is studied and analyzed. Finally, a 35 kW, 1200 r/min single-stator dual-rotors surface mounted permanent magnet motor is manufactured and tested. The temperature rise of the prototype under rated working conditions is tested to verify the effectiveness of the proposed cooling system, which provides an efficient and reliable cooling solution for winding heating caused by electromagnetic loss under high torque density output of AFPM motor.