A Novel Open Circuit Fault Detection and Diagnosis Method for Dual-Active Bridges Under Parasitic Coupling

This paper explores the reliability of Dual-Active Bridges (DABs) with a focus on open circuit faults (OCF). Unlike regular CHB inverters, DAB converters exhibit a change in current direction every switching cycle, impacting the response to OC faults. The proposed fast OCF detection method for DABs under parasitic coupling conditions leverages the drain-source voltage (VDS) of MOSFET. OCF-induced parasitic coupling in the primary voltage (Vpri) results in an elevated output voltage with oscillations. The analysis examines healthy and faulty operations on the primary side, with fault detection based on mean current value monitoring and analysis of anomalies in VDS. The proposed fault detection method involves measuring VDS's oscillatory behavior through signal conditioning steps, validated through simulations and experiments. The method proves effective in detecting faults within 20 µs. The paper also explores parameters affecting oscillation frequency during a fault. In conclusion, the proposed method provides a concise and efficient approach for fast OCF detection in DABs under parasitic coupling conditions, with potential applications in various DAB topologies. The study suggests extensions and highlights the method's compatibility with other fault detection approaches, offering valuable insights for practical implementations in DAB systems.