Partial power DC-DC converter for large-scale photovoltaic systems

Abstract

In photovoltaic (PV) systems, a wide variety of power converter topologies and PV configurations have been developed in order to increase the system efficiency. Traditionally, grid-connected PV systems use one or two conversion stages. The single conversion stage is mainly used for large-scale PV systems working with only a DC-AC converter. Whereas, for small and medium-scale, two conversion stages are used. The advantages working with a DC-stage are mainly the distributed maximum power point tracking (MPPT) algorithm and the elevation capability, but it presents a reduced conversion efficiency compared with the single stage configurations. On the other hand, the single conversion stage presents a reduced overall efficiency produced by partial shading. The proposed work presents a Partial Power DC-DC converter (PPC) which process only a portion of the whole power, reducing the conversion losses. It includes the benefits of two stage configurations so that it performs individual MPPT. Besides, due to the modularity of the architecture, it allows the parallel connection of many strings as required to use in large-scale PV systems. Simulations are performed in order to evaluate the converter performance.