Abstract: The aim of this study is to achieve online monitoring of the junction temperature of double-sided-cooling insulated gate bipolar transistor (IGBT) power modules by using the on-state voltage under a high current to maximize the utilization of IGBT power chips. Online junction temperature measurement plays an important role in improving the reliability of the inverter with IGBT, increasing the power density of the motor controller of electric vehicles, and reducing the cost of electric vehicles.