Cooling Effect of Water Channel with Vortex Generators on In-Wheel Driving Motors in Electric Vehicles

Designing an effective cooling system for high-power-density in-wheel motors of electric vehicles is required to avoid the irreversible demagnetization of the permanent magnet due to a rise in its temperature. In this study, a water-cooling channel was used between the stator and housing to evaluate the cooling performance of a 25 kW in-wheel motor utilizing the commercially available software Ansys Fluent 19.2. Initially, cooling channels with a single or pair of vortex generators have been used with varying heights for pressure drop evaluation considering the allowable pressure drop of 0.7 bar for a water pump. The results indicates that both a single and a pair of vortex generators satisfy the limit of a pressure drop at the height of 4 and 3 mm, respectively, and the cooling performances of two vortex generators were evaluated at these heights. It has been found that the cooling performance of a permanent magnet is enhanced by 4.1% and 6.5% using a single and a pair of vortex generators, respectively, compared to the cooling channel without a vortex generator. Furthermore, considering the ram air effect on water-cooling channels of in-wheel motors under high-speed conditions, the temperature of the permanent magnet is decreased by about 2.1 degrees C and was found to be 148.8 degrees C under the temperature limit of demagnetization of the permanent magnet.