DC-AC inverter based on a Cycloconverter output stage with active filter for peak power reduction in transformer and switches

Converters used for interfacing a DC to AC medium voltage grid, constructed from a Voltage Source Inverter (VSI) connected to a Cycloconverter output stage, via a high frequency transformer (DC/AC), have several advantages when compared to a DC-DC converter combined with an Voltage Source inverter (DC/DC/AC) as the output stage, but also some major shortcomings. This paper focuses on one of these shortcomings, the installed power in the high frequency transformer and associated switches. This is necessary because the transformer in the DC/AC converter processes twice the peak power of the transformer in the DC/DC/AC converter. It is proposed that by adding an additional 3 phase Voltage Source Inverter (VSI) active filter, connected to a flying capacitor, to each of the single phase DC/AC inverters the peak power required from the transformer and switches can be reduced.