Research On Non-Isolated Three-Port Converter Based On H-Bridge

The stand-alone renewable power system is widely used in hybrid electric vehicle and space satellite applications.Due to the instability of natural environment,the output power of the new energy resources has the characteristics of intermittence and instability.The energy storage unit is mandatory for the stand-alone renewable power system to solve the real-time power mismatch problem.Compared with employing several independent two-port converters,three-port converters(TPCs)show the advantages of high integration,high efficiency and unified power management.Starting from meeting the requirements of separate charging and discharging circuits for energy storage element(ESE),a family of non-isolated three-port converter by embedding a ESE-centric H-bridge cell into the classic Buck,Boost and Buck/Boost converters is proposed.Based on the composition and connection method of circuit elements,there are two types of embedding mode:(1)Without connecting with component of the classic converter,H-bridge is inserted into the classic converter directly.(2)Having connected with component of the classic converter in a specific way,the H-bridge is then connected with the rest part of the classic converter.The port voltage restrictions the obtained TPC are given.The proposed TPC family includes the advantages of the easy-to-derivation feature,single-inductor and single-stage power conversion among the three ports.By observing the TPCs generated by different embedding modes of H-Bridge,the operating mode and power flow configuration of the obtained TPCs are analyzed and summarized.TPCs developed from H-bridge connected with the load of Buck converter are compared and analyzed in terms of the operational principle and operation range under different ports’ voltage restriction.The research results show that different embedding modes of H-Bridge lead to the diversity in operating mode,power flow configuration and operation range of the obtained TPCs.Engineers can screen the TPCs according to the characteristics of applications.From the deduced general average equations for LP-3-Buck/Boost TPC,the small-signal models for different operating modes are derived.The energy management strategy for the converter is given so that the smooth transition of dual-output mode,dual-intput mode and the battery-only mode can be realized.The LP-3-Buck/Boost TPC prototype and the simulation model for a closed-loop control system have been carried out to verify the feasibility of the operational principle and the energy management strategy.Finally,the embedding method of H-bridge for non-isolated three-port converter is further extended to the derivation of non-isolated multi-port converter topology.Taking S-1-L-1 multi-port converter as an example,operational principle in the each operating mode is analyzed,and the voltage relationship between ports is derived.The corresponding simulation model is built to verify the correctness of its operating mode and operational principle analysis.