A series-resonance-based three-port converter with unified autonomous control method 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 systems (ESSs) into DC microgrids (MGs). In this paper, a hardware-decoupling approach using series-connected capacitor in a TPC is proposed and studied. In this series-resonance-based TPC, the decoupled power flow model among different ports is derived based on the equivalent model of the converter and the operation principle of the resonant circuit. Considering the characteristics and operation modes of photovoltaic (PV) and energy storage unit (ESU), which are connected at the two input ports of the TPC, a unified control method based on minimum value competition logic is proposed to achieve voltage regulation of the common bus in DC MGs. Experimental results are obtained in different test scenarios to demonstrate the effectiveness of the proposed method.