Application issues of an online temperature estimation method in a high-power 4.5 kV IGBT module based on the gate-emitter threshold voltage

A method for estimating the junction temperature based on the static and quasi-static gate-emitter threshold voltage has been previously presented. However, several questions that remained open, such as the physical meaning of the estimated temperature and influence of external parameters in the temperature estimation, are now addressed in this paper. If devices are paralleled the proposed method extracts the lowest threshold voltage and therefore the highest temperature. The influence of unequal temperature distribution among the dies of a 4.5 kV/1.2kA IGBT module is investigated as well as the influence of a variation of the threshold voltage of individual chips and among different modules of the same device family. Additionally to these device specific variations the influence of the integrated gate resistors is investigated and the feasibility for an industrial application is discussed.