AC Converter with LLC Resonant Converter High Frequency Link and
Four-Quadrant Switches in the Output Stage
Abstract
An AC-AC converter with high-frequency link employing LLC resonant
converter operating in the vicinity of the resonance frequency is
studied, in which the output stage is unique and formed by a
high-frequency AC-AC converter employing four quadrant switches. The
topology, its operation and the modulation strategy are presented. The
high-frequency stage switches located on the primary side of the
transformer operate with soft switching of the ZVS type, while the four
quadrant switches that form the output stage operate with soft switching
of the ZCS type. Experimental data on a 1.5 kW experimental prototype
that was designed, built and tested in the laboratory, with 220 VRMS
input, 220 VRMS output and 40 kHz switching frequency are given in the
paper. The studied converter can be considered a candidate for the
building block of medium voltage solid-state transformers (SST) for
power distribution systems.