Series-series association of two Dual Active Bridge (DAB) converters

This paper proposes a modular isolated dc-dc converter based on the series-series association of Dual Active Bridge (DAB) converters. The main attribute of the proposed topology is its ability to provide self-balance of the voltages on both sides of each individual converter, without voltage loop control, both in steady state and transient operations due to the natural circuit losses. Other important attributes are the voltage stress reduction in switches, due to the series-series association, and the fact that it has bidirectional power flow capability. The study of capacitor voltage balancing mechanism and theoretical analysis are included in the paper along with experimental results obtained from a prototype with two modules, 400 Vdc on the source side A and 400 Vdc on the load side B, 400 W of power, and 40 kHz switching frequency. Certain possible applications include high-voltage bidirectional direct current source supplies and interconnection of high-voltage direct current (HVDC) transmission lines.