IGBT Fault Current Limiting Circuit

There is a growing market demand for insulated gate bipolar transistors (IGBTs) with high efficiency but long short-circuit withstand time. The inherent device tradeoff, however, does not allow device designers to achieve both goals simultaneously. The proposed circuits, by limiting the fault current magnitude, extends the short-circuit withstand time of high efficiency (high-gain) IGBTs. Limiting of the fault current magnitude also results in reduced turn-off voltage transients; a desirable byproduct, especially for higher current modules. Moreover, the adverse Miller effect is counterbalanced to a great degree. If the fault current is of short transient type, the circuit restores normal operation, a unique and desirable feature for noise-prone systems.