An Improved Open‐Circuit Fault Diagnosis for Dual Active Bridge DC/DC Converter Employing SOGI

ABSTRACT The DAB‐based isolated DC/DC converter emerges as a preferred topology for high‐power DC/DC conversion due to its adeptness in achieving efficient power transfer while ensuring galvanic isolation. Moreover, to enhance reliability, it is crucial to address potential vulnerabilities such as open‐circuit faults (OCFs) resulting from semiconductor device failures. So, detecting faults in a DAB converter is crucial to prevent any potential escalation and mitigate further damage. This study delves into a comprehensive analysis of the characteristic waveforms of the inductor current and phase voltages of a DAB converter for both normal and various fault‐mode conditions. However, in practical cases, detecting such fast voltage variations requires high bandwidth filters that are not discussed in existing literature. Based on analysis an improved logic‐based fault diagnosis scheme is proposed with improved SOGI‐based filter leveraging the distinctive pattern of the inductor current and single‐leg midpoint voltage of each side of the H‐bridge. The proposed system utilizes two voltage sensors and one current sensor to detect all types of OCFs across all switches of DAB converter. To validate and analyze the proposed fault diagnostic method, verification through experimental setup of 2.5 kW is developed.