Stability Control Design for TAB-Based Three-Port Bidirectional DC/DC Converters in PV-Battery Grid-Connected Applications

As affected by climate conditions, e.g. solar irradiation and temperature, the output power of photovoltaic (PV) generation is generally random and intermittent. Energy storage devices like batteries are thus necessary to be incorporated in a PV system to smooth the output power. In order to connect the PV-battery to the DC grid, a three-port bidirectional DC/DC converter based on the triple-active-bridge (TAB) topology is a superior choice. Such three-port converter is a strongly coupled system, which demands decoupling control methods to obtain independent control of input/output power in each port. However, the conventional control strategy with decoupling control cannot suppress the filter resonance in DC-grid-port effectively and could lead to the converter output current instability. Therefore, a stability control design for TAB-based three-port bidirectional DC/DC converters is proposed in this paper. It can manage the power flow among the ports with reliability and maintain the system stable operation. Simulation results are finally presented to verify the proposed control design.