High Efficiency Quasi-Single-Stage DAB-DC/AC Converter With Wide Input Voltage Range

The single-stage dual active bridge (DAB) dc/ac converter is unable to maintain its input and output voltages matched to the transformer ratio over the ac cycle. This results in the limited soft-switching range and high current stress. A quasi-single-stage DAB-dc/ac converter consisting of the four-switch buck–boost converter and the DAB-dc/ac converter is proposed in this article. For the proposed converter, the input voltage of the DAB stage is controlled by the dc/dc stage, which ensures the matching of the input and output voltages of the DAB stage with the transformer ratio. As a result, the current stress of the DAB stage is reduced, and its soft-switching range is extended, thus improving efficiency across a wide input voltage range. In this article, the principle of operation, current stress, and soft-switching range of the proposed converter are analyzed in detail. Moreover, a 500 W experimental prototype is built to verify the theoretical analysis.