Design of Solid State Circuit Breaker

DC microgrids require fast and reliable means of overcurrent protection. Typical fuses, electrothermal circuit breakers, and hybrid solutions are too slow for microgrids that are usually highly capacitive and have reduced inductance. Solid state circuit breakers with a MOSFET as a switching element provide a solution. Although the power loss of such a device can be higher than that of the device with mechanical contacts, the reaction speed is the decisive factor. The control of such devices can be divided into fast short-circuit detection with discrete elements based logic circuits and slower microcontroller-based overload protection, fault management, and data communication. This paper analyzes the design factors of MOSFET-based solid-state circuit breaker (SSCB), and its control circuits. A prototype SSCB with a nominal current of 16 A is designed for 350 V DC residential microgrids and tested. Materials in this paper can be used to compare the widely used electrothermal circuit breakers with those of solid state and to support the design of new SSCBs for residential DC microgrids.