Solid-State Circuit Breaker Based on Cascaded Normally-On SiC JFETs for Medium-Voltage DC Distribution Networks

Solid-state circuit breakers (SSCBs) are critical components in the protection of medium-voltage DC distribution networks to facilitate arc-free, fast and reliable isolation of DC faults. However, limited by the capacity of a single semiconductor device, using semiconductor-based SSCBs at high voltage is challenging. This study presents the details of a 1.5 kV, 63 A medium-voltage SSCB, composed primarily of a solid-state switch based on three cascaded normally-on silicon carbide (SiC) junction field-effect transistors (JFETs) and a low-cost programmable gate drive circuit. Dynamic and static voltage sharing among the cascaded SiC JFETs of the SSCB during fault isolation is realized using the proposed gate drive circuit. The selection conditions for the key parameters of the SSCB gate driver are also analyzed. Additionally, an improved pulse-width modulation current-limiting protection solution is proposed to identify the permanent overcurrent and transient inrush current associated with capacitive load startup in a DC distribution network. Using the developed SSCB prototype and the fault test system, experimental results are obtained to validate the fault response performance of the SSCB.