High-Efficient Isolated AC-DC Converter with Circulating Current Reduction for AC Adapters

Abstract:
This paper proposes a circulating current reduction of an isolated AC-DC converter based on a dual-active half-bridge converter. This converter has the capability of power factor correction, DC voltage control, and Zero Voltage Switching (ZVS) to reduce the switching loss. This circuit has the variable duty control in the secondary full-bridge rectifier to achieve the power factor correction. In this control method, the design of the modulation index is important to determine the performance of the power factor correction and conversion efficiency. This paper introduces the design method of the modulation index focusing on the circulating current reduction. As an experimental result, the conversion loss was reduced by 40.1%. Finally, the maximum efficiency is improved to 95.3% from 92.1%.