Modelling of IGBT with High Bipolar Gain for Mitigating Gate Voltage Oscillations during Short Circuit

In this paper, the impact of the PNP bipolar transistor gain on the short-circuit behaviour of High Voltage Trench IGBTs is analysed. The short circuit ruggedness against high-frequency oscillations is strongly improved by increasing the hole current supplied by the collector. By doing so, the electric field at the emitter of the IGBT is increased and less influenced by the amount of the excess charge (i.e., the electric field is fixed). The charge-field interactions during the short circuit event, leading to a periodic charge storage and charge removal effect and provoking miller capacitance variations, can be mitigated. The effectiveness of using IGBTs with high bipolar gain is validated through both simulations and experiments, also a design rule to trade off the IGBT’s losses and short-circuit robustness is provided.