Bidirectional Parallel Low-Voltage Series High-Voltage DAB-based Converter Analysis and Design

The system requirements of galvanic isolation with bidirectional energy flow capability create new opportunities for research and development in power conversion with applications in renewable and energy storage systems. A dual active bridge converter derivation topology with transformer parallel low-voltage (LV) and series high-voltage (HV) windings connected to three full-bridges is investigated in this research work. The common-mode current circulation, which leads to increased electromagnetic emissions, has been reduced within the DAB-based converter through the proposed design approach. The design methodology aims for magnetics comparison and modulator design for soft-switching power conversion operation. The parallel-LV and series-HV DAB-based converter has been evaluated with two different transformers. The typical designs for high-current transformer windings are with copper foil. The drawbacks of high interwinding capacitance have reduced by five times through a specific transformer construction. The experimental results show improved results with respect to electromagnetic emissions. Furthermore, the DAB-based converter has been compared in hard-switching and soft-switching operation with respect to electromagnetic emissions. The experimental results have been performed using a 5kW rated power DAB-based converter with silicon carbide (SiC) power semiconductors.