Experimental characterisation and modelling of high-voltage IGBT modules off-state thermal instability

This paper proposes the experimental characterization and modeling of thermal runaway phenomena affecting high-voltage devices in the blocking state. In particular, it considers 6.5 kV rated multi-chip IGBT modules, of the kind employed in railway traction applications, showing how temperature and reverse bias voltage influence the off-state power losses and how the same thermal design may yield thermal instability for devices of different manufacturers. Additionally, evidence is shown of significant temperature mismatches for the chips within a module, which enhance the risk of failure. In order to analyze all of these effects, an advanced modeling technique is applied, which couples analytical models of semiconductor physics with a 3D numerical model of thermal effects. This allows for an in-depth, still handy analysis, useful for optimized and reliable thermal design.