Design and Modelling of Three-Port Bidirectional DC-DC Converter for PV-Battery Integrated DC Microgrid Systems

This paper proposes a novel non-isolated bidirectional three-port converter (TPC) based on a KY boost converter and an interleaved boost converter for photovoltaic (PV) powered and battery-buffered systems. The proposed three-port converter integrates ports of the PV array, battery pack and DC microgrid bus bar. Proposed converter is composed of two power switch, an LC filter for battery, boost inductor for PV array and KY boost converter, which is consist of a charge pump capacitor and two series switches. In the proposed converter, the charge pump capacitor and boost inductor provide a voltage gain, thus, the number of series battery cells and PV array can be reduced for a lower cost. On the other hand, a two-control loop scheme has been designed to control power flow between the ports and perform a smooth transition between the loops. To test the effectiveness of the proposed TPC, a MATLAB/Simulink-based simulation model has been developed with a 1 kW PV array, 37 V 10 Ah battery pack and 64 V DC microgrid. The performance of the proposed converter has been analyzed for different case studies and loading conditions. According to the simulation results, 96% peak efficiency of the converter has been achieved and maximum power from PV has been extracted with MPPT mode selection. The results show that the proposed converter has some advantages in terms of the number of switches, multi-loop control, bidirectional power flow, cost and efficiency.