Thermal Design of Air-Cooled YASA AFPM Motor with Heat Pipes

This paper proposes a new forced air cooling with heat pipe auxiliary for yokeless and segmented armature (YASA) axial flux permanent magnet (AFPM) motors. Since the heat transfer path of stator for single stator double rotor (SSDR) AFPM machine is restricted, the heat pipes provide auxiliary heat dissipation paths for the windings and stator. Firstly, the winding cooling structure with auxiliary heat pipes of YASA AFPM motor is introduced because the introduction of heat pipe will occupy winding space and itself will also produce loss due to flux leakage in slots, the optimization of winding loss and heat pipe size becomes a key issue. Then, fins are added to the surface of the shell and end covers to increase the heat dissipation area and enhance convection heat exchange. Based on the Computational Fluid Dynamics (CFD), the size of the heat pipe and the fins get optimized in this paper. The temperature distribution of YASA AFPM motor are obtained. The results show that when the length, width, and height is respectively set to 18mm, 5mm, and 102.5 mm, the interaction between the thermal and electromagnetic performance reduces the peak temperature of YASA AFPM to $146.31 ^{\circ}\mathrm{C}$, which has certain reference significance for improving the operational reliability of the AFPM synchronous motors in YASA structures.