A hybrid full-bridge three-level DC-DC converter with crossing auxiliary capacitors

Abstract

This paper presents a high-power medium-frequency hybrid full-bridge (FB) three-level (TL) DC-DC converter with crossing auxiliary capacitors. In this converter, two auxiliary capacitors are deployed between phases a and b, replacing the flying capacitor. The converter’s three-level leg switches are with low voltage stress, while the two-level leg switches are with high voltage stress. The topology and modulation method, as well as the switching characteristics of the hybrid FBTL DC-DC converter with crossing auxiliary capacitors are described. The feasibility and performance of the above-mentioned converter is validated by a laboratory prototype. Based on the mechanism analysis and experiments, the zero-voltage switching (ZVS) and zero-switching loss (ZSL) of power switches, self-balance of the clamped capacitors voltages, and the voltage self-balance of the switches in the three-level leg can be achieved.