An IEGT Model for Analyzing the High Current Turn-off Characteristics in DC Circuit Breaker Applications

The direct current (DC) circuit breaker based on semiconductor power devices is one of the critical components in multiterminal flexible high voltage DC transmission technology. A press pack injection enhanced gate transistor (IEGT) can realize a low on-state voltage similar to a gate turn-off (GTO) thyristor while achieving better high current turn-off capability and wider safety operating area than an IGBT. Therefore, an IEGT is a promising candidate for high voltage DC circuit breaker applications. The fault current conducted by devices in DC circuit breaker applications is 4~6 times the device rated current, which brings great risks to reliable operation. Optimizing the device turn-off characteristics and then realizing reliable operation are indispensable parts of DC circuit breaker design. For analyzing the high current turn-off characteristics under the working conditions of a DC circuit breaker, an IEGT model is proposed in this paper. In the model, a simple method for predicting the static-state I-U characteristics is established. In addition, based on the differences in the gate structures of IEGTs and IGBTs and the influence of the gate structure on the nonlinear capacitances between device terminals, the nonlinear capacitances are greatly improved to better describe the turn-off transient process. Subsequently, the model is verified by experiments. The model is expected to be a convenient simulation tool for designing a high voltage DC circuit breaker with IEGTs.