Estimation of IGBT Module Degradation Using Foster's Model and Structure Function

This study proposes to evaluate the IGBT module and detect weaknesses before conducting accelerated life tests, using Foster's model and the Cumulative Structure Function (CSF). A commercial module was chosen, and the Foster parameters provided in the datasheet were obtained. The behavior of the junction temperature was simulated using the Piecewise Linear Electrical Circuit Simulation (PLECS) software. The concept of degradation factor was employed by varying the Foster parameters, thus simulating module degradation in a virtual environment. Specifically, the effects of these variations on Junction Temperature
$(T_{j})$
, Thermal Impedance
$(Z_{th})$
, and Cumulative Structure Function (CSF) were observed, leading to the conclusion that the degradation factor alters these parameters. The experimental results focus on acquiring and measuring the Virtual Junction Temperature using TSEP and obtaining the thermal impedance curve, which is then compared with the datasheet values.