Isolated High Gain DC-DC Converter with Low Input and Output Current Ripple for Photovoltaic System Applications

Abstract

This paper proposes a DC-DC high gain converter topology for applications in photovoltaic systems connected to microgrids and nanogrids. The presented topology aims to obtain low ripple current source characteristics at the input and output of the converter, to respectively satisfy the tracking of the maximum power point and avoid the beat phenomenon in a DC bus, which can reduce the quality of the power injected into the bus. Galvanic isolation aims to comply with the safety standards established in some countries for photovoltaic systems. This paper initially presents the theoretical foundation for the proposed topology. Then the converter operation stages are described, allowing the equation of each stage. A more accurate expression for the gain is shown, as it considers the influence of the converter's transformer leakage inductance. The paper also shows the sizing of the input and output inductors, as well as the coupling capacitor. The experimental parameters obtained from the photovoltaic panel and the transformer are presented below, allowing for quantitative simulation analyses. A comparison between the simulation and theoretical values is made, resulting in simulated current gain and ripple values that validate the theoretical model. Finally, the efficiency of the converter is estimated to be 96.48%.