Modeling, Analysis and Implementation of Junction-to-Case Thermal Resistance Measurement for Press-Pack IGBT Modules

Press-Pack IGBT modules are becoming increasingly attractive in many applications due to its device structure and short-circuit failure mode. Junction-to-Case thermal resistance (R_thjc) of Press-Pack modules is of great importance for power converter and cooling design, as well as reliability assessment. However, it is challenging to accurately achieve R_thjc of Press-Pack modules due to the Press-Pack device structure. This paper presents an accurate R_thjc measurement for Press-Pack modules based on the Transient Dual Interface Measurement (TDIM) method. The key to success of accurately measuring R_thjc of Press-Pack modules is revealed. Due to the difficulties of further decreasing the contact thermal resistance from module case to heat sink, this paper determines the R_thjc splitting point by increasing the contact thermal resistance from module case to heat sink. Analysis and modelling of the R_thjc measurement system for Press-Pack modules are presented. Finally, experimental results demonstrate the differences between the conventional methods and the method in this paper, which validates the analysis and modelling of R_thjc measurement for Press-Pack power modules.