Three-Phase Four-Wire AC–DC–AC Converter With Shared Legs

This article proposes a three-phase four-wire ac-dc-ac converter with legs shared between grid and load sides. This topology is suitable for operation as uninterruptible power supply and unified power quality conditioner. Also, two scenarios of the converter are considered, first, load and grid voltages with same amplitude with possibility to compensate grid-voltage swells, and second, grid voltage with twice the amplitude of load. Converter model, pulsewidth modulation, control strategies, and passive elements design are developed. Comparisons between conventional and proposed topologies in terms of harmonic distortion and semiconductor losses are carried out. The proposed converter is suitable for operation in low-voltage high-power applications, presenting lower conduction losses than the considered conventional topologies.