Two-Segment High-Performance PV Grid-Connected Inverter

In PV grid-connected applications, a grid-connected converter is usually used to connect with the grid to realize dc/ac conversion and power flow control. How to improve the quality of grid-connected current of power equipment so that the harmonic content injected into the grid is as little as possible has become a hot research topic in the field of PV grid-connected applications. By analyzing the causes of grid-connected harmonic currents during the grid-connection process, a two-segment high-performance grid-connected inverter topology is proposed. This structure makes the main inverter basically equal to the grid voltage through the simplest closed-loop control. Since the voltage sensitivity of the auxiliary inverter is low, utilizing the auxiliary inverter for the compensation of grid-connected voltage and grid-connected control of power flow will lead to an improvement in the quality of grid-connected current. A 3.3 kW grid-connected inverter system prototype is fabricated and tested, and the experimental results verify the stability and effectiveness of the theoretical analysis and the proposed control scheme.