Interlink Three-Level Bidirectional DC-DC Converter with Asymmetrical Load Condition

Due to dc based electric loads and renewable sources, the dc distribution system is an alternative future solution. Among the dc distribution systems, the bipolar dc type has higher performance and reliability than the unipolar one. To interlink two dc buses, an isolated bidirectional DC-DC converter is needed. A three-level dual-active-bridge DC-DC converter is proposed to interlink two bipolar dc buses. Between two dc buses, a galvanic isolation is provided by the high frequency transformer of the three-level dual-active-bridge. Besides, an asymmetrical switching modulation is proposed to compensate asymmetrical load condition of the bipolar dc bus system. Finally, a 1-kW prototype is built to verify the proposed converter.