An asymmetrical quadruple active bridge series resonant DC–DC converter for modular solid-state transformers

The DC–DC conversion stage of a three-stage solid-state transformer is the most challenging due to the combination of high power, medium voltage, and medium frequency. This combination also causes most of the losses in the DC–DC stage. To address this issue, a new asymmetrical quadruple active bridge series resonant DC–DC converter (AQAB-SRC) has been proposed as a building block for solid-state transformers. The converter achieves soft switching of all switches throughout the operating range by extending and using the half-cycle continuous conduction mode control strategy. It also has fewer high-frequency transformers compared to other converters, as more bridges are connected to the same multi-winding transformer. The optimal design of AQAB-SRC has been analyzed theoretically, and simulation and lab-scale experimental results have been obtained to validate the feasibility and validity of the proposed topology.