Temperature Field Analysis and Heat Dissipation Optimization for In-Wheel Motor Based on Magnetic-Thermal Coupling

To address the challenge of heat dissipation in electric vehicle in-wheel motors within limited space, this study conducted temperature field analysis and cooling structure optimization based on magnetic–thermal coupling. The three-dimensional finite element model and the magnetic–thermal-coupled mathematical models of synchronous permanent magnet in-wheel motors were established. Using a coupled electromagnetic–thermal finite element analysis method, numerical simulations were performed to investigate the transient temperature fields of the in-wheel motor under different driving conditions. The effects of three different cooling channel structures on the temperature rise and the pressure drop of the in-wheel motor were compared, and a parallel channel structure suitable for the in-wheel motor was selected. The influences of channel quantity, channel width, and coolant flow rate on the temperature field were analyzed. Furthermore, a multi-objective optimization of the cooling structure was carried out using the NSGA-II genetic algorithm. The simulation results demonstrated a significant improvement in the overall thermal performance of the optimized cooling structure. The maximum temperature of the hub motor decreased by 2.25% and 3.32% under the rated and peak speeds, respectively, while the pressure drop in the water channel was reduced by 58.52%. This study provides a theoretical reference for temperature field calculation and cooling structure design of hub motors.