High Step-Up Three-Port Converter with Coupled-Inductor and Voltage Lift for Sustainable Energy Systems

Typically, the source voltages of a single photovoltaic module with energy storage battery system are low, in which converters with high step-up gain are required. This study proposes a non-isolated three-port converter with compact size that utilizes three-winding coupled inductor and switched capacitor techniques to achieve high voltage gain with lower voltage stresses of power switches for photovoltaic module with energy storage system. The voltage gain from photovoltaic to output is improved by cascoding the switched capacitor voltage with photovoltaic voltage. For increasing the voltage gain from battery to output, the coupled inductor technique is adopted. The proposed three-port converter can be operated in five power converting stages among three ports, and regulate the power transferring independently. The operational principles, steady-state analyses, and key parameters design of the proposed topology are presented in detail in this paper. Finally, the laboratory prototype is built to verify the theoretical analyses, with photovoltaic voltage of 24V, battery voltage of 48V, and load voltage of 200V. The maximum efficiency among the five operational stages in this article is 98.1%.