Nonisolated Wide Operation Range Three-Port Converters With Variable Structures

In the standalone renewable power system, three-port converters (TPCs) are widely used to interface a renewable source, a storage battery, and a load, simultaneously. In nonisolated applications, TPCs without transformers usually suffer from ports' voltage restrictions. Such a drawback limits TPCs' operation range because of changeable renewable source voltage and storage battery voltage. In this paper, the TPCs with variable structures are proposed. Compared with the existing available nonisolated TPCs, the proposed TPCs have the loose ports voltage restrictions because of variable structures among ports, and thus feature the wide operation range. These variable structure TPCs can also realize the needed power management requirements. What is more, these variable structure TPCs can be compact size since only one inductor is applied. In this paper, one of the variable structure TPCs is taken as an example for detail analysis. Operational modes of this TPC are designed and optimized for different power management requirements in different ports' voltage restrictions, and control scheme is also designed. The experimental results are also given to validate the analysis.