Two-stage grid-connected inverter topology with high frequency link transformer for solar PV systems

Abstract

This study introduces a new topology for a single-phase photovoltaic (PV) grid connection. This suggested topology comprises two cascaded stages linked by a high-frequency transformer. In the first stage, a new buck–boost inverter with one energy storage is implemented. The buck–boost inverter can convert the PV module’s output voltage to a high-frequency square wave (HFSWV) and can enhance maximum power point tracking (MPPT) even under large PV voltage variations. The high-frequency transformer gives galvanic isolation for the system, which decreases the leakage current and improves the system power quality. The second stage of the topology involves using a rectifier-inverter system to interface the produced HFSWV to the utility grid. The proposed system uses high switching frequency which increases the power density, reduces the grid filter size, and increases the system reliability. Buck–boost DC/AC inversion, MPPT and low grid current injection are implemented. The working principles of the proposed topology have been investigated, and the theoretical and experimental results are developed and analyzed.

Keywords

• Buck–boost inverter
• PV
• High frequency transformer
• MPPT