A Three-Port DC-DC Converter for Energy Exchange in Microgrids

Renewable energy microgrids with solar photovoltaic sources and batteries are becoming more common in small-scale power systems. In these applications, distributed energy sources are tied into a microgrid with either a dc bus or an ac bus. To improve the reliability and flexibility of those applications, this paper proposes a new three-port dc-dc converter (TPC) for energy sharing in microgrids with a common dc bus. This paper presents the converter’s multiple power flow modes depending on the microgrid interface interaction. Two of the modes are selected and analyzed in detail, with focus on modulation strategy and mathematical model. A unified nonlinear model is derived, and the average model is provided based on the nonlinear model. The simulation model is built in MATLAB/Simulink to validate power flow control and modeling accuracy by comparison, and an experimental setup is established for further validation.