Discrete-time small-signal modeling of a 1 MHz efficiency-optimized dual active bridge converter with varying load

A discrete-time, small-signal model is developed for the dual active bridge (DAB) converter which considers the effects of zero-voltage switching (ZVS) intervals on converter dynamics. The model is applied to the converter operating under phase-shift modulation, and is shown to be valid across a full range of load values constituting multiple operating modes of the converter. Finally, the model is applied to the case of an unregulated converter to show that output voltage variation that results in improved efficiency over wide range of loads can also lead to simplified control and compensation requirements across the full load range.