Research On Transient Thermal Impedance Measurement Method Of Power IGBT Devices During Heating Process

Insulated Gate Bipolar Transistor(IGBT)is an indispensable core component in the fields of high-voltage and high-power power electronic equipment and rail transit.Examining the thermal characteristics of power IGBT devices,especially the accurate measurement and analysis of transient thermal impedance,plays a crucial role in device condition monitoring and reliability evaluation.The transient thermal impedance of press pack IGBTs devices exhibits different properties during the heating and cooling processes.Accurate measurement of the transient thermal impedance during the heating process can lay the foundation for the multi-physical field coupling research and aging monitoring of press pack IGBTs.After decades of research and development,academia and industry in domestic and foreign have done a lot of research work on junction temperature measurement methods for power IGBT devices.However,the various junction temperature measurement methods proposed have different applicability in different situations and purposes.There are few junction temperature measurement methods suitable for measuring the transient thermal impedance of IGBT during heating processes in this paper,and two applicability issues need to be addressed.One is to meet the requirements of continuous junction temperature measurement during the heating process of power devices,and the other is to meet the requirements of accurate junction temperature measurement for various packaged IGBT devices,including press pack IGBTs.This paper focuses on the equivalence of heating curve and cooling curve of power IGBT device and the applicability of junction temperature measurement methods to the measurement of heating curve of various packaged IGBT devices,the research on junction temperature measurement methods is carried out to improve the accuracy of junction temperature measurement,laying a foundation for the research on accurate junction temperature measurement technology and reliability of power IGBT devices.A finite element simulation model was established to investigate the equivalence of heating curve and cooling curve of power IGBT devices,revealing the essential reason and influence mechanism of the non-equivalence of heating curve and cooling curve of press pack IGBTs.For the applicability and feasibility of the junction temperature measurement method under high current,an experimental platform based on the junction temperature measurement method under high current was established,which verified the feasibility of the junction temperature measurement method under high current on the experimental platform,and accurately measured the transient thermal impedance curve of the transistor outline IGBT device during the heating process.Using the threshold voltage(VGE,th)at high current method for heating curve measurement is proposed and verified on press pack IGBTs.This method effectively reduces the impact of contact resistance on measurement accuracy,with an error within 1K,and improves the accuracy of junction.Based on the accurate junction temperature measurement method,the heating and cooling curves were measured and compared,verifying the conclusions of finite element simulation,providing a reference for further research and aging monitoring of press pack IGBTs.