Based On Full-order State Observer To Predict Junction Temperature Of IGBT Module

With the rapid development of the times and technology,global energy shortages and environmental pollution problems are becoming more and more serious,and electric vehicles are gradually replacing traditional vehicles.As a component of the motor controller,the power device is one of the important parts of the electric drive system.Research shows that nearly one-third of the faults of the semiconductor power devices are caused by the failure of switching devices such as IGBTs,and more than half of the failures are due to temperature.In this paper,from the electrical and thermal aspects of IGBT,considering the mutual influence of electric and thermal parameters,the junction temperature state observer is designed to predict the junction temperature of IGBT in real time.In the electrical part,based on the principle of double pulse test,the IGBT switch dynamic characteristic test platform is built.The IGBT switch characteristics under different working conditions are tested to study the effects of on current,bus voltage and junction temperature on IGBT loss.Based on platform test data,The linear interpolation method is a detailed analysis to derive the mathematical model of IGBT switching loss and conduction loss.For the thermal part,this paper determines the main heat transfer path by analyzing the IGBT heat transfer process.The IGBT transient thermal resistance test platform is built for thermal resistance test.According to the linear dependence of the IGBT saturation voltage drop on the junction temperature of the device under constant small current conduction,the temperature and transient thermal resistance curves are obtained by measuring the saturation voltage drop.Based on the transient thermal resistance curve,the thermal resistance and heat capacity parameters are extracted to build a thermal network model.Based on the IGBT thermal network model,the state equations of each temperature node are derived.For the lack of feedback adjustment of the open-loop estimation of junction temperature based on the state equation,a full-order state observer is designed.The observer outputs the case temperature and the measured case temperature,the error between them is corrected in real time for the junction temperature estimate.The simulation model based on Simulink is built to realize the real-time prediction of junction temperature,and the accuracy and robustness of the method based on state observer for predicting junction temperature are verified.The junction temperature prediction experimental platform was designed and built,and the junction temperature state observer was discretized,and the software system development was realized based on the CCS environment.The junction temperature state observer is verified by the thermal parameter method,which indicates that the state observer can estimate the junction temperature in real time.At the same time,based on the experimental platform,the effects of IGBT on current,switching frequency,duty cycle and bus voltage on junction temperature are studied.