Non-Destructive Experimental Investigation about RBSOA in High Power IGBT Modules

Abstract:
Trends for the development of IGBTs are always aimed to obtain a sufficiently large safe operating area (SOA) as required by many power electronic systems operating under hard-switching conditions. The study of IGBTs robustness near SOA limits is a main step to develop high performance devices. The paper presents an experimental characterization of high power IGBT modules at currents beyond Reverse Bias SOA (RBSOA) and high junction temperatures. The analysis is aimed to understand the turn-off limits of power IGBT modules in typical hard switching applications and to discuss the possible failure mechanisms. The experimental characterisation has been performed by means of a non-destructive test set-up where the IGBT modules are switched in presence of a protection circuit that is able to prevent failures at the occurrence of any possible instability. The experimental analysis confirms the very good robustness of high power IGBT modules which can withstand large current overstresses well beyond the declared RBSOA limits even at temperatures larger than those one declared by manufacturers.