A Three-Port Bidirectional Multi-Element Resonant Converter With Decoupled Power Flow Management for Hybrid Energy Storage Systems

A three-port bidirectional multi-element resonant converter is developed in this paper. It contains multiple resonant components, which leads to various resonant frequencies. Due to the appropriate placement of these frequencies, the transfer of the fundamental and the third-order harmonic active power is guaranteed. Besides, a non-ideal isolated transformer is considered, as the parasitic leakage inductor is often ignored for the multi-port resonant converter. A systematic design procedure is proposed to reduce the coupling power between two input ports. It turns out to be instructive for the decoupled power flow management of the multi-element resonant converters. Preferred parameters are easily selected by means of the small signal model established in this paper. It contributes to the improvement of degree of control freedom consequently, with respect to the complex decoupling matrices. In the end, a 750-W prototype is built in the laboratory. The feasibility of theoretical analyses is verified by experimental results. In addition, zero-voltage-switching characteristics for all the power switches of the three ports are achieved. The highest conversion efficiency is 96.3%.