Hardware Decoupling and Autonomous Control of Series-Resonance-Based Three-Port Converters in DC Microgrids

A three-port converter (TPC) as a compact dc/dc energy conversion unit can effectively integrate renewable energy sources (RESs) and energy storage units (ESUs) into dc microgrids (MGs). In this paper, a series-resonance-based isolated TPC is developed to integrate photovoltaic (PV) and ESUs into dc MGs. A hardware decoupling approach using a series-connected capacitor in the half-bridge of the isolated TPC is proposed and studied. The decoupled power flow model among different ports is derived based on the equivalent circuit model of the converter, and the power transmission principle of the resonant circuit is analyzed. On this basis, considering the characteristics and operation modes of PV and ESU, which are connected at the two input ports of the TPC, a unified autonomous control method based on minimum value competition logic is proposed to coordinate the operation of PV and ESU, and achieve voltage regulation of the common bus in dc MGs. Simulation and experimental results are obtained in different test scenarios to demonstrate the effectiveness of the power decoupling effect and the proposed control method.