An Integrated Three-Port DC/DC Converter for High-Voltage Bus Based Photovoltaic Systems

In high-voltage bus based photovoltaic systems, a power electronic interface is required to manage the power flow in between the PV panel, battery, and the high-voltage dc bus. In this paper, a novel three-port dc/dc topology is proposed for this application. Pulse width and phase shift offer two degrees of freedom to effectively regulate the power flows. On the primary side, the input current ripple is reduced due to the interleaved structure. This avoids the usage of the bulky electrolytic capacitor on the PV terminal. On the secondary side, a voltage sixfolder rectifier is employed to boost the step-up ratio. This reduces the turns number on the secondary-side of the transformer. Moreover, the voltage stresses of secondary-side MOSFETs and diodes are reduced to one-third of the output voltage. Zero-voltage switching and zero-current switching are realized among all power MOSFETs and diodes respectively and in an extended range. A 500 W converter prototype, linking a 40 V-60 V battery pack, a 20 V-30 V PV panel, and a 760 V dc bus, is designed and tested to verify the proof-of-concept. Both the circuit functionality and theoretical analysis are validated by the experimental results.