Effects of Thermal Characteristics of Power Module on Electric Vehicle Inverter

The thermal characteristics of power modules have a great impact on the performance of the inverter system in electric vehicles. The poor thermal characteristics of power modules will reduce the efficiency, power density, and reliability of the EV inverter. This paper studied the thermal characteristics of power modules under different power and thermal conditions and their influence on system performance in the EV inverter. The thermal resistances of Si IGBT and SiC power modules were measured by electrical method. The results showed the thermal resistance will be variated under several different input currents, cooling water flow rates, and inlet water temperatures. The thermal resistances of Si IGBT and SiC power modules were compared and discussed. We studied the structure-function to analyze thermal resistance in different material layers of the power module to find the heat transfer bottleneck in the Si IGBT and SiC power modules. Finally, by using the electro-thermal RC model coupled with the power loss model, the thermal effects on the inverter system were studied.