Single-phase soft-switching AC-link buck-boost inverter

Soft-switching ac-link buck-boost converters, also known as ac-link universal power converters and partial resonant ac-link converters, have received remarkable attention during the last few years. These converters can be configured as dc-dc, dc-ac, ac-dc, or ac-ac (single-phase or multi-phase). Among the numerous advantages of these converters are compactness, higher reliability, and longer lifetime compared to the other types of converters. Soft-switching ac-link buck-boost converters are in essence an extension of the dc-dc buck-boost converters. Therefore, they can both step up and step down the voltage. Unlike the traditional buck-boost converters, the inductor current in these converters is alternating and all the switches have zero-voltage turn-on and soft turn-off. The high-frequency ac link in soft-switching ac-link buck-boost converters allows the use of a single-phase high-frequency transformer for providing the galvanic isolation. The application of this new class of power converters in the three-phase dc to ac, three-phase ac to dc, and three-phase ac to ac conversion has been successfully evaluated. The three-phase soft-switching ac-link buck-boost inverter is currently available in the market and listed in the California Energy Commission (CEC) list of approved photovoltaic inverters. In this paper the application of this converter in the dc to single-phase ac conversion will be studied in detail and two single-phase inverter configurations will be proposed.