Modeling and Control of a Four-port DC-DC Converter for a Hybrid Energy System

This paper presents modeling and controllers design of a four-port DC-DC converter for integration of a hybrid energy system which includes a photovoltaic (PV) panel, wind turbine generator (WTG), and a battery. A small signal model is first derived from the differential equations of the converter in different operation stages. Based on this model, four controllers are developed to control the voltage and current of the battery, and the output voltage of the converter while eliminating the coupling item between two voltage loops. Simulation and experimental studies are carried out and validate that these controllers are capable of controlling the power flow of renewable energy sources, battery, and the load. Besides, they can protect the battery from over-charging and over-discharging while maintaining constant DC link voltage.