An Integrated Topology of Three-Port DC-DC Converter for PV-Battery Power Systems

This paper introduces an integrated topology of isolated three-port dc-dc converter (TPC) to interface Photovoltaic (PV) and battery for standalone system. To guarantee zero circulating current flow between different ports while permitting bidirectional power flow at the battery port, auxiliary switches are utilized with the active bridges of the proposed TPC topology. In addition, a simple switching scheme based on Pulse Width Modulation (PWM) is proposed for the input ports of the TPC. This action eliminates the need for the phase shift modulation used for conventional isolated TPCs. While the PV port is controlled to track the maximum power point, the battery port is managed to regulate the load voltage. The paper presents the detailed mathematical analysis of the different operation modes of the proposed integrated TPC topology and the estimated control limits during charging and discharging of the battery. Consequently, dynamic limiters for the duty cycle of each port are set. The proposed integrated TPC based PV-battery system is simulated using PSCAD/EMTDC software package to validate the analysis of different operation modes and to assess the dynamic performance of the system. Moreover, experimental results are presented to authenticate different operation modes of the proposed TPC topology and to evaluate the dynamic behavior of the integrated PV-battery system.