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.

Power electronic systems have been widely applied in both industrial and domestic applications in the modern society for controlling and converting electrical energy. Due to their characteristics, such as excellent performance, low cost, high reliability, and low weight and size, power semiconductors, including insulated-gate bipolar transistors (IGBTs) dominate the market of power converters. The technical progress and development trend of IGBT for industrial applications are primarily driven by five aspects influenced by each other to an extent, including operating temperature, efficiency, dimension, reliability, and cost. Liquid cooling systems surpass the air cooling systems by supplying heat transfer coefficient, which is several orders of magnitude higher. Thus, using liquid cooling system enables much higher power densities of power modules and more compact converter solutions.