An Ultra-Efficient DC Hybrid Circuit Breaker Architecture Based on Transient Commutation Current Injection

Safety and protection against circuit faults represent a major technical challenge in emerging DC transmission and distribution power networks. This paper proposes a new DC hybrid circuit breaker (HCB) architecture that relies on a switching-mode Transient Commutation Current Injector (TCCI) circuit instead of the prior-art Load Commutation Switch (LCS). The TCCI in the electronic path remains in a standby mode with near zero power loss under normal conditions but can rapidly generate a pulse current matching the fault current, and therefore facilitate current commutation from the mechanical to the electronic path. It completely eliminates the conduction power loss associated with the LCS, and delivers an ultrahigh transmission efficiency. The TCCI circuit provides a near-zero voltage and a small high-frequency AC ripple current condition for the mechanical contacts to separate arclessly. A 600V/20A HCB prototype based on a dual-input current source buck converter topology experimentally demonstrates that a fault current of 40A is commutated within 10µs, and only a small, high frequency AC ripple current is maintained through the mechanical switch afterwards.