Three-phase bidirectional dc/ac converter using a six-leg inverter connected to a direct ac/ac converter

In this study, a three-phase bidirectional dc/ac converter is proposed using a direct ac/ac converter and a six-leg converter, to avoid the use of dc-link capacitors and to increase the current capability at the dc side. To link the six-leg inverter to the direct ac/ac converter, three single-phase high-frequency transformers are implemented to simplify the topology, which will attract the industry. The direct ac/ac converter used in the study demonstrates reduced complexity and simpler modulation techniques compared with a conventional matrix converter. The analysis starts with the description of the proposed dc/ac converter for single phase, which is subsequently extended to a three-phase dc/ac converter. A 20 kW prototype was built to verify and to validate the theoretical study of the proposed converter.