Reclosable Bidirectional Z-Source DC Circuit Breaker Suppressing Source-Side Fault Reflection and Reverse Recovery Spikes

In this article, a new bidirectional dc circuit breaker (DCCB) topology based on Z-source principles is presented. The new DCCB topology is featured with the reprotection capability and safely protects the dc source and load even when a utility controller tries to reengage the DCCB with an uncleared fault. Our topology is efficient as it only includes one semiconductor device in its current path during normal operation and is symmetrically built to provide bidirectionality. With an additional current path for a fault, our new DCCB suppresses the reflection of the fault current onto the source side, enhancing equipment protection. Detailed mathematical models are built in this article to analyze the protection mechanism, operation performance, and short-circuit fault responses. This article also discusses how to expedite the fault-clearing and reclosing processes. In addition, this article explores the impact of the reverse recovery of semiconductor devices in DCCBs and provides a mitigation strategy. A laboratory-scale prototype is built to validate the theoretical analyses and verify the benefits of the proposed bidirectional dc circuit breaker topology.