Modified dual buck-boost AC/DC converter with self-balanced DC output voltages

With wide applications of DC loads and renewable energy generation sources, the DC micro-grid becomes more and more attractive, especially regarding active AC/DC converters. Recently, a high-efficiency buck-boost AC/DC converter with three terminal outputs has been presented for DC micro-grid. However, the main drawback of this converter is that the output voltages become unbalanced in the case of unequal DC loads, which causes a challenge in practical applications. In this study, a modified buck-boost AC/DC converter with self-balanced DC output voltages is proposed. Equivalent circuits are used to analyse the operating principle of the proposed converter. As an important part of the proposed converter, the coupled inductor is designed, while the design procedure is described in detail. The dead-beat control method is adopted to shape the waveform of the coupled inductor current. A 220 V/50 Hz/1.5 kW prototype is developed, and detailed experiments are carried out to corroborate the validity of the proposed converter.