Monitoring of IGBT modules - temperature and degradation simulation

This paper presents an overview of the challenges in online monitoring of on-state voltage in high power insulated gate bipolar transistor modules used for temperature and degradation assessment. Through a detailed simulation approach, based on the finite element method, an estimation of the impact on on-state voltage from inhomogeneous temperature fields and material degradation of interconnects are presented. Temperature estimation from on-state voltage is normally based on a steady state calibration procedure which compared to real life application with dynamic loads are insufficient. Similarly, change in on-state voltage from degradation of multiple interconnects is difficult to separate into specific contributors and thereby apply in lifetime estimation models. Therefore simulation results are sought combined with experimental data to increase accuracy of estimation of temperature and degradation of individual elements.