A Refinement Multilevel Turn-off Method for Dynamic Latch-up and Tail Current Suppression in DC Breaker Ultra-High Current Switch Applications

The instantaneous current turn-OFF capability of the insulated gate bipolar transistor (IGBT) devices has always been an important indicator to determine the turn-OFF performance of the dc circuit breakers (DCCBs). The two main failure types for IGBT devices in DCCB applications are dynamic latch-up and tail current thermal breakdown. However, the mainstream traditional turn-OFF methods cannot effectively solve all failure types in DCCB applications. Instead, suppression of one failure type tends to increase the risk of another failure type. This article proposes a refinement multilevel turn-OFF method that successfully decoupled the main failure types of IGBT devices during turn-OFF and realizes the control of two key parameters dV(CE)/dt and I-tail0 independently. The influence mechanism of two key parameters is revealed through comprehensive analysis and calculation. The effectiveness of the multilevel turn-OFF method in suppressing two key parameters is verified by technology computer aided design (TCAD) simulation and experiment. Finally, the turn-OFF ability of a 4.5kV/1.2 kA IGBT is increased from 12 to 17.6 kA (10 p.u. to 14.7 p.u.), which can significantly increase the allowable working area of IGBTs, thereby significantly reducing the cost of dc circuit breakers.