The aim of this research was to investigate the torque performance of the motor in an electric vehicle depending on the rotor shape and air gap. The research focused on numerical comparison of torque performance of new rotors based on the average torque and torque ripple rate, which appeared according to the number and placement of permanent magnets. This research was numerically analyzed by MAXWELL V21.1. Average torque values in cases 1, 2, and 3 were increased, but vibration and noise in cases 1 and 3 were increased as the torque ripple rate increased. Considering the average torque and torque ripple rate, the torque performance of case 2 was the most optimal. Compared with Model N, the average torque of case 2 was increased by 9.1% and the torque ripple rate was reduced by 1.5%. The torque performance according to the size of air gap was compared with the basic model of case 2, which showed the best performance. An air gap of 0.7 mm applied to Model N showed the best torque performance. An additional magnet on case 2 and air gap of 0.7 mm provided the best torque performance and improved the driving motor performance for motor durability.

The objective of this study was to numerically accomplish the cooling performance of an electric vehicle driving motor depending on cooling channel design. Cooling performances of novel cooling channels were compared based on the temperature of coils and cooling channels as well as convection heat transfer coefficient in electric vehicle driving motors. Local axial positions of cooling channels at three different cases were marked for numerical comparison of heat transfer coefficients. Owing to forced convection by the boundary and flow conditions, the heat transfer coefficient of Case 3 at the location where pin-fins were attached in the cooling channel was improved 85.02 and 65.77% compared to Cases 1 and 2, respectively. In Case 3 with pin-fins having 50% of cooling channel length, the maximum temperature of the coil was 4.25% lower than that of Case 2 with pin-fins having 30% of the cooling channel length and 6.98% lower than that of Case 1 without pin-fins in the cooling channel. As a result, pin-fins finally diminished the maximum temperature of coils in Cases 2 and 3. Ultimately, Case 3 showed the best cooling performance for improving vehicle driving durability and developing next-generation electric vehicle cooling system technologies.

This research investigated the cooling performance of the motor in electric vehicle depending on the shape of the cooling channel. The research, conducted numerically by FLUENT V20.1, focused on the numerical study of heat transfer coefficients to find an optimum design shape with high cooling performance. To compare the cooling performance, the temperatures in the coil and cooling channel were analyzed. As a result of forced convection, the average cooling channel velocity of Case 2 was 38% faster than Model N and 34% faster than Case 1. The maximum temperature of the cooling channel of Case 2 was 8.7% lower than Model N and 5.6% lower than Case 1. The minimum temperature of the coil of Case 2 was 2.7% lower than Model N and 4.3% lower than Case 1. The maximum temperature of the coil of Case 2 was 4.6% lower than Model N and 2.9% lower than Case 1. Ultimately, cooling channel of Case 2 showed the best cooling performance and improved driving performance for motor durability.