A Family of Multiport Buck-Boost Converters Based on DC-Link-Inductors (DLIs)

A systematic method for derivation of a multiport converter (MPC) based on the dc-link inductor (DLI) concept is proposed in this paper. The MPC is generated by interconnecting multiple pulsating voltage cells (PVCs) through the DLIs. The PVCs can be input type, output type, and bidirectional type, and bidirectional MPC topologies can be harvested if all the PVCs are bidirectional type. As a result, a family of novel MPCs, including multiinput converters, multioutput converters, and bidirectional MPCs, are derived. With the proposed MPCs, step-up and step-down voltage conversion between any two of the ports can be implemented. As an example, the three-port bidirectional buck-boost (TP-B-3) converter is analyzed and applied to a stand-alone renewable power system for interconnection of three dc subsystems. The operation principles, pulse width modulation, and feed-back control strategies are presented and analyzed in depth. The analysis indicates that, compared to the traditional common dc-bus-based solution, bulky dc-link capacitor is eliminated and single-stage conversion between any two of the three dc-buses are achieved with the TP-B-3 converter, which is beneficial for higher efficiency, power density, and reliability. Experimental results are given to verify the feasibility and effectiveness of the developed TP-B-3 converter.