The Single-Active Bridge (SAB) converter is ideal for DC-DC conversions requiring galvanic isolation, unidirectional power flow, high efficiency, and power density. It operates at a constant frequency with regulation capability, avoiding the electromagnetic compatibility issues of resonant converters. The SAB achieves Zero Voltage Switching (ZVS) for all MOSFETs and can be implemented with a single magnetic component by optimizing the transformer's leakage inductance. However, the transformer reduces efficiency and power density in high step-down conversions. This paper introduces a novel SAB version that mitigates this issue by incorporating a switched-capacitor structure, reducing voltage across the transformer's primary winding. This allows for higher step-down conversions and easier integration of series inductance into the transformer. Additional benefits include soft charge/discharge of the switched capacitor, reduced voltage stress across three MOSFETs, and no transformer saturation. Experimental results from a 400V-to-24V converter prototype operating at 100kHz with a peak output power of 350W are provided.
