A Novel Soft-Switching Multiport Bidirectional DC–DC Converter for Hybrid Energy Storage System

A novel multiport isolated bidirectional dc-dc converter for hybrid battery and supercapacitor applications is presented, which can achieve zero voltage switching for all switches in the whole load range. The bidirectional power flow between any two of the ports is free, and the circulating power is low for the well matching of the transformer voltages of all time regardless of the voltage variations of the battery and supercapacitor. Moreover, the current ripples are greatly decreased by interleaved control, which is good for battery and supercapacitor. The converter topology and the operation principle are introduced. Detailed analysis on soft-switching of all switches is given. On the basis of theoretical analysis, the principle and method for parameter designing are provided. A hybrid energy management strategy combining bus voltage control and energy management of the energy storage devices is proposed and the control scheme is presented. Moreover, detailed parameter design of a prototype converter is given for a 380-V dc-bus microgrid lab system. Effectiveness of the control strategy, correctness of the analysis on soft-switching, and the parameter design methods are verified by the simulation and experimental results.