A Novel Family of Single-Phase Direct Buck AC-AC Converters With Continuous Input Current, Reduced Components, and Balanced Power Losses

Abstract

This paper introduces a single-phase step-down AC-AC converter designed for voltage sag/swell compensation applications. The converter features a minimal component count, continuous input current, and high efficiency, although only one power switch operates at a high frequency per input voltage half-cycle. It offers a linear and broad voltage conversion ratio (D) without right-half-plane zeros in its small-signal transfer function, simplifying the controller design. The proposed converter does not need dead time. It ensures balanced voltage and current stresses and power losses among power switches, easing the selection of semiconductors. Compared with existing topologies, it excels in total capacitor voltage, switching device power, and volume metrics of capacitors and inductors, thereby reducing cost and size. Experimental results from a 250-W prototype demonstrate a peak efficiency of 94.8% and effective voltage sag/swell mitigation as a DVR.