Predicting junction temperature of IGBT module based on full-order state observer

Abstract:

To accurately estimate the junction temperature and solve the over-temperature problem, a junction temperature state observer is designed to predict the junction temperature of IGBT in real time considering the mutual influence of electrical and thermal parameters. First, the effects of conduction current, bus voltage and junction temperature on IGBT loss are studied on the offline test platform of IGBT. The mathematical model of IGBT loss was derived by linear interpolation method. Second, a thermal network model is built up based on the IGBT transient thermal resistance test platform. Last, the state equations of each temperature node are derived and a full-order state observer is designed to compensate the drawback of open-loop state equation. The error between output shell temperature and the measured shell temperature is corrected in real time on full-order junction temperature observer. To verify the effectiveness of the designed method, simulations carried out on Matlab\\Simulink and experiment setup are established. The simulation and experimental results show that the predicted junction temperature can track the target value, and the designed method is validated.