Dual Mode Medium Voltage Solid-State Circuit Breaker Based on Mass-Produced SiC JFETs

Abstract:
The supercascode switch concept involves series-connecting SiC JFETs and controlling their simultaneous switching with a single low-voltage MOSFET and a gate bias network. The supercascode automatically turns on to allow reverse current to flow, similar to a body diode in a MOSFET. The result is a high performance and cost-effective building block for both medium voltage power converters and SSCBs. Many SSCB applications require fast turn-off during a fault condition, but slow turn-on to limit inrush current. Two innovations to address this requirement are presented. First, using different gate resistances for turn-on versus turn-off for one JFET. Second, adding analog current control to the supercascode results in a dual mode SSCB. Design aspects and use as unidirectional and bidirectional multifunction SSCBs are explained. Simulation results are presented.