Open-Circuit Fault Mode Analysis and Fault Tolerant Operation for DAHB DC-DC Converter

The Dual-Active Half-Bridge (DAHB) converter is a widely recognized interface for renewable energy applications, known for its simple configuration and outstanding performance. In critical industrial applications, such as electric vehicle charging, it is essential to maintain the ability to transmit the target power, even when encountering with open-circuit faults (OPF). Unlike the Dual-Active Bridge (DAB) converter, which generates a bias current in the highfrequency transformer under OPF conditions, the DAHB converter avoids this issue due to the presence of split capacitors. However, an OPF in the DAHB converter causes an imbalance in the split capacitor voltages and prevents the achievement of the target voltage output, which are key fault features unique to the DAHB. Furthermore, the distinct topological structures of the DAHB and DAB converters mean that existing fault-tolerant strategies designed for DAB cannot be directly applied to DAHB. To address these challenges, this paper analyzes the operating modes of the DAHB under various fault conditions and first proposes a fault-tolerant operating mode specifically tailored for the DAHB converter.