A New Buck-Boost AC/DC Converter with Two-Terminal Output Voltage for DC Nano-Grid

Due to the development and deployment of renewable DC power sources and their inherent advantages for DC loads in applications, the DC nano-grid has attracted more and more research attentions; especially the topologies of AC/DC converters are increasingly studied. When designing an AC to DC converter for a DC nano-grid system, the grounding configuration, which determines the costs, the efficiency as well as the safety, plays an important role. A three-terminal output AC to DC converter based on united grounding configuration has been presented for DC nano-grid. However, it has to be pointed out that the three-terminal output DC nano-grid is not as popular as the two-terminal DC output one, due to the infrastructure consideration. This paper proposes a new Buck-Boost AC to DC converter with two-terminal output voltage for DC nano-grid. The operating principle, the steady-state analysis, and the small signal modelling for the proposed converter working in continuous conduction mode are presented in detail. A 220 V/50 Hz/800 W prototype was fabricated to verify the effectiveness of the proposed converter.