A PV DC Boost Collection Converter Based on Capacitor Isolation

With the large-scale centralized development of solar power plants, DC collection systems are gradually replacing traditional AC collection systems with the advantages of higher efficiency and better stability. Currently, most DC/DC converters in photovoltaic (PV) DC collection systems use high-frequency transformers (HFTs), such as DAB and LLC. Wide-bandgap devices such as SiC and GaN promote an increase in the switching frequency of DC/DC converters, but they increase the iron loss in the magnetic core, which has to reduce the system switching frequency in practical applications, resulting in a waste of high switching frequency performance of the wide-bandgap devices. This paper proposes a novel circuit topology that replaces HFTs with LC resonant networks for energy transfer and uses a filter network to achieve good suppression effect for the common-mode component. This solution not only avoids iron losses but also realizes the isolation of converter inputs and outputs, thereby enhancing overall efficiency and reducing the weight. This converter can switch between Maximum Power Point Tracking (MPPT) mode and constant output voltage mode, and to output self-balancing voltage at each stage, making it an apt solution for PV DC collection systems.

I. Introduction

In recent years, PV solar power generation has developed rapidly due to its environmentally friendly attributes and its ease of installation and maintenance [1]. Despite its benefits, PV panels inherently present characteristics of low output voltage and significant random fluctuations, which must be boosted by the collection system to reach the grid connection conditions.