A T-type three-level converter for wide-range voltage application

Fuel and solar cells are broadly used in Microgrids. However, their output varies widely when load and environment change extensively. Thus, DC-DC converters are used for wide-range voltage application. Nevertheless, output filter inductor is large and voltage stress of diodes is high in two-level converters when input voltage varies widely. Therefore, a T-type three-level converter is proposed. A T-type cell is added into the full-bridge (FB) converter. The proposed converter can work in two- and three-level modes, that is, 2L and 3L modes. It works in 2L mode in high input voltage. Thus, the output filter inductance and voltage stress of diodes in 2L mode decrease compared to the FB converter. Operating principle is illustrated. In addition, design guidelines and examples are shown. Finally, experimental results confirm the theoretical analysis.