Fully Soft-Switched DC Solid-State Circuit Breakers

This letter presents a new fully soft-switched dc solid-state circuit breaker. During dc current interruption, both main and auxiliary switches turn
off
under zero current switching (ZCS). A novel inductor–capacitor–capacitor-based active injection circuit is proposed. It eliminates transient power on switches with a fast operation, which enhances reliability. Experiments of a 350 V/90 A prototype validate the ZCS operation for both switches. The response speed reaches 4 μs, and the maximum voltage on switches is 759 V, which is within a safe range. This letter is accompanied by slides as multimedia material demonstrating major innovations and contributions.