Enhancement of cooling performance in traction motor of electric vehicle using direct slot cooling method

•DSC(Direct Slot Cooling) has been proposed for high-power and high-torque traction motors.•To evaluate the performance of DSC, we compared it with existing motor-cooling technologies, such as water-jacket, end-tip and channel coolings.•DSC enables a 66% and 94% increase in the applied current density compared to that of water-jacket cooling and end-tip cooling, respectively.•By adopting the DSC model, the winding maximum temperature did not exceed 90 °C in the highway driving mode, even when a high current density of 70 A/mm2 was momentarily applied.