A Novel Multi-Port Bidirectional Converter for Interfacing Distributed DC Micro-Grid

A novel multi-port bidirectional DC-DC converter (MPBDC) is proposed for a stand-alone renewable power system which is composed of multiple distributed DC sub-systems. With the proposed MPBDC, the DC buses of these sub-systems can be interconnected with single stage and step-up/-down power conversion. The MPBDC is derived by interconnect multiple bidirectional buck/boost switching cells via DC-link inductors. The equivalent circuit between any two of the DC buses is a H-Bridge step-up/-down converter, which achieves single stage conversion. Compared with the conventional common DC-bus-based solution, the bulky DC-link capacitors have been eliminated with the MPBDC, which benefits reduced size, lower cost and better reliability. The operational principles, power management and pulse width modulation scheme are presented in detail. A prototype is built with experimental results given to verify the topology and control.