A Single-Stage Isolated AC-DC Converter Based on the Impedance Control Network Architecture

This paper introduces a new single-stage universal input isolated ac-dc converter based on the impedance control network (ICN) architecture. This resonant converter performs both power factor correction (PFC) and output voltage regulation while operating at a constant switching frequency and duty ratio, by modulating the phase-shift between its two half-bridge inverters and the phase-shift between the two legs of its full-bridge rectifier. This phase-shift control strategy along with the ICN architecture also enables the converter to achieve high efficiency by ensuring zero-voltage-switching (ZVS) and near-zero-current switching (ZCS) of all its inverter transistors throughout the line cycle and across wide ranges of input line voltage and output power. Power density is enhanced by realizing the three ICN inductors using a single magnetic structure with two coupled windings. This coupled inductor and a transformer constitute the two magnetic components of the proposed converter. A systematic methodology to design this ICN-based ac-dc converter is also introduced. A universal-input (90-265 Vrms), 20-V output, 330-W, 400-kHz ICN-based ac-dc converter prototype is built and tested. This prototype achieves a power density of 37.9 W/in3 and peak efficiencies of 91.7%, 92.2%, 93.2% and 93.4% at 90 Vrms, 120 Vrms, 230 Vrms and 265 Vrms input, respectively.