Split-Capacitor-Based Isolated Double Step-Down DC-DC Converter

This article introduces a novel isolated high step-down dc-dc converter. The introduced converter can offer the low voltage stress of power switches on the primary side. The introduced converter also achieves a zero-voltage-switching turn-on for all power switches and avoids the transformer saturation problem. By using a split-capacitor double step-down structure, the introduced converter also reduces the input capacitance and eliminates the high voltage stress during the start-up process. The introduced converter is ready to be connected to a three-level NPC inverter with self-balanced voltages in two capacitors of the dc link. The operating principle and comparative study of the introduced converter are presented in detail. A 1-kW 400-/48-V laboratory prototype was implemented to validate the feasibility of the introduced converter.