3-D Thermal Network Modeling and Thermal Analysis of an Air-Cooled Yokeless Stator Axial Flux PM Motor With Heat Pipes

This article proposes a high-efficiency air-cooled method suitable for yokeless and segmented armature (YASA) axial flux permanent magnet (AFPM) motor. The high cooling performance is obtained by inserting heat pipes with high thermal conductivity in the slots to provide auxiliary heat dissipation paths for the windings and stator core. Then, based on a three-dimensional lumped parameter thermal network (3-D LPTN) of the axial flux motor, an improved winding modeling method considering the loss distribution and temperature transfer gradient is established. The model is refined into partitioned modules to account for stator and rotor temperature gradients and winding loss distribution. Subsequently, the temperature of each node obtained by LPTN is compared with that obtained by computational fluid dynamics (CFDs). Finally, a 35-kW YASA AFPM motor is tested, and the experimental temperature matches well with the predicted temperature calculated by two different simulation methods.