Modeling and Control of a Four-port DC-DC Converter for a DC Microgrid with Renewable Energy Sources

In this paper, modeling and control design of a four-port bidirectional DC-DC converter for integration of various energy sources to a DC microgrid is proposed. The power transferring through the transformer is first derived from the steady-state waveforms. Based on the power analysis, three controllers are developed to regulate the battery voltage/current, and the power flow between the energy sources and the DC microgrid, respectively. The converter is used to interface a wind turbine generator, a PV panel, battery, and the DC microgrid. With the designed controllers, the four-port DC-DC converter is not only capable of performing the maximum power point tracking (MPPT) for the two renewable energy sources, but can achieve bidirectional power flow between the energy sources and the DC microgrid as well.