Transient Mitigation in Dual Active Bridge Converter Using an Auxiliary Converter with High-Frequency Selective Control for Load Step-Down Condition

Dual Active Bridge (DAB) converters are widely employed in applications such as electric vehicles, renewable energy systems, and solid-state transformers due to their high efficiency, galvanic isolation, and bidirectional power flow capability. However, under rapid load transitions, DAB converters experience significant output voltage overshoot and extended settling time, which may cause increased stress on power devices and reduced system reliability. This paper presents an auxiliarycircuit-based transient mitigation method designed to address these limitations. The proposed auxiliary circuit, implemented as a bidirectional Buck-Boost stage, operates in Boost mode during load step-down conditions to absorb excess energy and attenuate the overshoot. The auxiliary converter and its corresponding control schemes are described in a systematic manner, and both simulation and experimental validation of the approach are presented. Simulation results of a 15 kW DAB demonstrate that the proposed method effectively reduces voltage overshoot and shortens settling time compared with the conventional DAB topology. Experimental results from a scaled prototype confirm that the auxiliary circuit provides fast transient compensation, achieving improved dynamic performance and stable voltage regulation under sudden load variations with ∼60%, reduction in voltage overshoot.