Planar Rogowski Coil Based Short-Circuit Detection and Partial Open-Circuit Recovery of the Resonant Capacitor in Series-Resonant DC Transformers

The 10 kW Series-Resonant DC Transformer (SR-DCX) enables both switch and resonant element count reduction and is a building block of a bidirectional two-stage dc–dc converter for 600–28 V MIL-PRF-GCS600 A and MIL-STD-704F compliant applications. The dc–dc converter is constructed with its first stage as a buck converter and the second stage as the SR-DCX. Failure mode assessment of the SR-DCX indicates a single-point failure on the resonant capacitor that will either prohibit or degrade the operation of the dc–dc converter, depending upon the failure mode. This article discusses the design of a planar Rogowski coil in accordance with MIL-PRF-31032 and its signal chain optimization for the measurement of ac current on the high-frequency link. We introduce a novel failure detection method to simultaneously identify both partial open-circuit (OC) and short-circuit failures in the resonant capacitor network by re-purposing the ac link current measurement, conventionally used for over-current protection. The method also enables recovery from partial OC failures to restore normal operation. The proposed scheme aids in raising system-level warnings for redundancy activation prior to catastrophic failures in the dc–dc converter for high-reliability applications.