Analysis of heat and cooling characteristics of hub motors in electric vehicles

• Aiming at the overheating problem of electric vehicle hub motor, the temperature rise and heat dissipation characteristics of the motor under different working conditions were studied. • The hub motor models of natural cooling and circulating water cooling were established by finite element method , and the cooling effects of different cooling methods and cooling structures were analyzed. • The temperature distribution characteristics of the wheel motor and the corresponding cooling method with better effect are obtained. In consideration of the thermal issues associated with the electric vehicle hub motor operating at high temperatures, a comprehensive analysis was conducted by integrating heat transfer theory and fluid dynamics. This involved simulating and scrutinizing the temperature elevation and heat dissipation characteristics of the motor across distinct operational scenarios and cooling methodologies using finite element simulation. By aligning these simulations with experimental data, the temperature distribution pattern within the motor operating under low-speed flat road conditions and overloaded hill-climbing conditions was determined. Moreover, the impact of various cooling mechanisms on the motor’s heat dissipation characteristics was assessed. Subsequent examination of cooling system parameters and cooling medium facilitated the identification of an optimized cooling system structure. The findings highlighted substantial variations in radial temperature distribution under different operational conditions and cooling techniques, while axial temperature distribution variances were minimal. Notably, due to the air gap barrier effect, specific motor regions exhibited pronounced temperature concentration; the stator and winding zones were characterized by high temperatures, whereas the rotor and motor casing areas remained comparatively cooler. Under low-speed operating conditions, the hub motor demonstrated minimal temperature increases. Conversely, during overload scenarios, the motor exhibited elevated heat dissipation demands surpassing the capacity of natural air cooling. Comparative analysis indicated that circulating water cooling outperformed natural air cooling, yielding a more uniform temperature distribution across the motor and satisfying performance criteria. The study recommended an optimal configuration of 22 waterways, providing essential insights for the future design of an enhanced cooling system structure.