A High Conversion Ratio Converter Based on Tapped-Series Capacitor Circuit

A high conversion ratio converter is detailed analyzed in this article. Inspired by partial power structure, the proposed topology can be divided into two circuits:
LLC
circuit and tapped-series capacitor (TSC) step-down circuit. The
LLC
converter operates under a constant operating frequency. The tapped-series capacitor converter is paralleled to output of
LLC
converter with closed-loop control to regulate the total output voltage with the high conversion ratio ability. The operational principle and parameter design method of proposed topology are explained in detail, especially the operating modes of TSC circuit. Meanwhile the structure of matrix transformer adopted in the
LLC
converter is optimized. The proposed converter can achieve both high conversion ratio ability as well as high efficiency with a wide input voltage range. A 400–5 V prototype is built and the testing results verify the advantages of the proposed converter.