Comparison of non-resonant and super-resonant dual-active ZVS-operated high-power DC-DC converters

Two bi-directional high-power dc-dc converter topologies with zero-voltage-switching (ZVS) operation over a defined load range are compared. These are the non-resonant dual-active bridge (DAB) and the dual-active series-resonant converter (DSRC) in super-resonant mode. A unified mathematical model describing both converters is presented, which treats the DAB as a boundary case of the super-resonant DSRC with infinite capacitance. It bases on a modification of the analytical analysis of the DSRC presented in [1]. Using the model, a method is developed to optimize the ac link transformer size for a limited dynamic voltage operating range with constant power capability, suitable for high-power converters in utility applications. The influence of the resonant capacitor on transformer size and other vital converter characteristics is quantitatively evaluated.