Design optimisation of self-powered gate driver for ultra-fast DC solid-state circuit breakers using SiC JFETs

Abstract

Solid-state circuit breakers (SSCBs) inherently have excellent protection performance, thus they are popular for DC distribution protection. However, the safety and reliability of the SSCBs are limited by the rapid response ability of their own gate drivers. In this study, a self-powered SSCB with a normally-on silicon carbide (SiC) junction gate field-effect transistor (JFET) is proposed as the solid-state switch, whose gate drivers are optimised as well. First, both an optimised fault detection circuit and a designed forward-flyback DC/DC converter of the SSCB gate driver have been presented to achieve fast protection during the course of fault isolation. Then, the detailed analyses of the gate driver circuit parameters effect on protection speed are further investigated based on circuit theory and MATLAB calculation. In order to compare and analyse the dynamic responses of the SSCB with and without optimisation, the actual interruption tests of the fabricated SiC JFET circuit breaker prototype and the employed prototype 400 V DC distribution system have been carried out. The results show that the implementation approach is able to improve protection speed for the SSCBs within the order of a few microseconds.