User-Programmable Short-Circuit Capability Enhancement for 1.2 kV Si IGBTs using a 40 V Si Enhancement-Mode MOSFET connected in Series with the Emitter

Abstract

Commercially available Si IGBTs are designed in two forms – i) optimized for low VCE,SAT but with poor SC ruggedness, and ii) optimized to achieve good short-circuit withstand capability but with high VCE,SAT. A new method is proposed to achieve good short circuit withstand capability for IGBTs designed with low VCE,SAT. A user programmable short circuit withstand capability is achieved using a low voltage Si enhancement mode power MOSFET (EMM) connected in series with the emitter. The proposed concept enables the applications engineer to achieve a desired short-circuit withstand time with minimal impact on on-state and switching performance. Experimental demonstration is provided with commercially available 1.2 kV Si IGBTs. A 2.3x improvement in tSC is achieved with a 24% increase in on-state voltage drop and less than 5% increase in switching losses. The proposed concept also provides a sense node at the drain of the EMM which can be used to monitor on-state currents and detect short circuit events.