Wide input range non-isolated three-port converters for stand-alone PV storage power systems

To address the instability of the input voltage of photovoltaic (PV) in a stand-alone PV storage power generation system, a wide input range non-isolated three-port converter that can operate in a range that is greater than and less than the voltage of the storage port is proposed in this paper. The proposed converter can realize the energy flow and power balance between the PV, the battery, and the load. This converter is a combination of conventional Buck, Boost, and Buck-Boost converters with a four-switch bi-directional Buck-Boost converter (FSBB). The FSBB is used to connect the PV and battery ports, which can reduce the voltage constraint of the storage port on the PV port voltage, and broaden the selection of the voltage levels of the storage port to meet the application requirements of the PV port with a wide voltage input. In this paper, an experimental prototype is designed by combining the Boost converter and the FSBB converter. Finally, the correctness of the theoretical analysis and the feasibility of the energy management strategy of the converter are verified through experimental results.