An on-state collector-emitter voltage (V _ce ) measurement and thereby an estimation of average temperature in space for high power IGBT module is presented while power converter is in operation. The proposed measurement circuit is able to measure both high and low side IGBT and anti parallel diode voltages for a half bridge module which are also used to monitor the electrical degradation of the module. The V _ce load current is proposed to estimate the variation of average temperature in space at every fundamental cycle of sinusoidal loading current. Initially, the calibration of voltage and junction temperature for load current level is presented and a trend of change in calibration factor for the IGBT is presented. Finally, the variation in temperature for sinusoidal variation of current is presented at initial stage and after an ageing of the IGBT. The measurement technique is simple and easy to implement into a gate driver for field applications.