Design and Evaluation of a Reconfigurable Stacked Active Bridge DC-DC Converter for Efficient Wide Load Range Operation

This paper presents the design and implementation of a large-step-down soft-switched dc-dc converter based on the active bridge technique, which overcomes some of the limitations of the conventional dual active bridge converter. The topology comprises a double-stacked bridge inverter coupled to a reconfigurable rectifier through a special three-winding leakage transformer. This particular combination of stages enables the converter to run in an additional low-power mode that greatly increases light-load efficiency by reducing core loss and extending the zero-voltage switching range. The converter is implemented with a single compact magnetic component, providing power combining, isolation, voltage transformation, and energy transfer inductance. A 175 kHz, 300 W, 380-12 V GaN-based prototype converter achieves 95.9% efficiency at full load, a peak efficiency of 97.0%, an efficiency above 92.7% down to 10% load, and an efficiency above 79.8% down to 3.3% load.