基于级联常通型SiC JFET的快速中压直流固态断路器设计及实验验证

固态断路器(solid state circuit breaker, SSCB)是直流配电网中实现快速、无弧隔离直流故障的关键保护装置。首先提出了一种基于级联常通型碳化硅(silicon carbide, SiC)结型场效应晶体管(junction field effect transistor, JFET)的新型中压直流SSCB拓扑，直流故障发生时利用金属氧化物压敏电阻(metal oxide varistor, MOV)向SSCB主开关级联常通型SiC JFET器件的栅源极提供驱动电压，可快速实现直流故障保护。其次详细分析了SSCB关断和开通过程的运行特性，并提出了SSCB驱动电路关键参数设计方法。最后研制了基于3个级联常通型SiC JFET器件的1.5 kV/63 A中压SSCB样机，通过短路故障、故障恢复实验验证了设计方法的有效性。结果表明该SSCB关断250 A短路电流的响应时间约为20 s，故障恢复导通响应时间约为12 s，为中压直流SSCB的拓扑优化设计和级联常通型SiC JFET器件的动静态电压均衡性能提升提供了支撑。

Design and experimental verification of an ultrafast medium-voltage DC solid-statecircuit breaker using cascaded normally-on SiC JFETs

The solid-state circuit breaker (SSCB) is a crucial component in the protection of DC distribution networks in that they facilitate reliable, arc-free, and fast isolation of DC faults. First, a novel medium-voltage DC SSCB topology based on cascaded silicon carbide (SiC) junction field effect transistors (JFETs) is proposed. When a DC fault occurs, metal oxide varistors (MOVs) are used to provide driving voltage to the gate-source terminals of cascaded normally-on SiC JFETs of the SSCB main switch. These can achieve fast DC fault protection. Additionally, the operational characteristics of the SSCB turn-off and turn-on processes are analyzed in detail, and the design method of key parameters of the SSCB drive circuit is proposed. Finally, a 1.5 kV/63 A medium-voltage SSCB prototype based on three cascaded normally-on SiC JFETs is developed, and the effectiveness of the design scheme is verified through short-circuit fault and fault recovery experiments. The results indicate that the response time for the SSCB to turn off the 250A short-circuit current is about 20 s. Fault recovery conduction response time is about 12 s. This provides a foundation for the topology optimization design of medium-voltage DC SSCB and the improvement of dynamic and static voltage balance performance of cascaded normally-on SiC JFETs.