A Unified Approach to Open-Circuit and Short-Circuit-Fault Detection and Localization in Three-Phase Dual Active Bridge Converters

This paper presents a unified, single-sensor-based method for detecting and localizing both open-circuit faults (OCFs) and secondary-side short-circuit faults (SCFs) in three-phase dual-active-bridge (TP-DAB) converters using the$\alpha \beta$framework. In the proposed approach, the existing current-sense resistor, traditionally used for output-current regulation, is repositioned to measure the unfiltered dc-link current, from which the required$\alpha \beta$parameters are extracted. This eliminates the need for additional current or voltage sensors, thereby reducing system complexity and cost. A 400-V, 6.5-kW gallium nitride (GaN)-based TP-DAB prototype, operating at 300 kHz and achieving a peak efficiency of 96.6%, was developed to validate the proposed method. Experimental results demonstrate that single-switch OCFs are detected and localized within 13$\mu$s (four switching cycles), while SCFs are detected within 268 ns-well within the short-circuit withstand time of the tested GaN devices. Thus, the proposed algorithm offers a practical and hardware-efficient solution for improving the reliability of onboard chargers.