Electronically Assisted Circuit Breaker (EACB) for DC Power Systems

This paper introduces a new DC hybrid circuit breaker concept termed Electronically Assisted Circuit Breaker (EACB). An electro-mechanical circuit breaker (CB) is used to interrupt DC currents with the assistance of a power electronic commutation circuit, which is only activated for a short time period during the late phase of the interruption process. Unlike other prior art of hybrid circuit breaker (HCB) concepts, the EACB uses (1) a conventional electro-mechanical AC breaker design with minimal modification and no additional sensors or actuators; and (2) an electronic commutation circuit which needs to carry current already reduced from its peak and only for a very short duration (~100μs), both contributing to significant cost savings. Other advantages include enhanced current interruption capability, self-powered and autonomous operation, and inherently low on-resistance. The EACB concept is validated both experimentally and by simulation. A 600VDC/250A (nominal) EACB prototype is designed and built, which experimentally demonstrates a fault current interruption capability of over 8kA at 600VDC within 6ms.