A High-Power-Density High-Efficiency Single-Phase Universal-Input to 28V Isolated AC-DC Converter Designed to Meet MIL-STD EMI Specifications

This paper presents a high-power-density high-efficiency single-phase universal-input to 28V isolated ac-dc converter. The proposed two-stage converter utilizes a totem-pole bridgeless boost converter followed by an isolated LLC resonant converter. A new comprehensive design methodology is presented, which compares various designs and operating modes for the power stage and selects the optimal design based on overall power density and efficiency. For the selected design, a control strategy is also presented which enables reduction in input current distortion and improves the input power factor. To validate the proposed design and control strategy, a 1-kW universal-input to 28V ac-dc converter is built and tested. The prototype converter achieves a high power density of 84 W/in3 and a peak efficiency of 93.3%.