Optimized 9-Level Switched-Capacitor Inverter for Grid-Connected Photovoltaic Systems

Abstract

This paper introduces a novel switched-capacitor-based 9-level inverter topology to meet IEEE standards for low total harmonic distortion (THD) in grid-connected inverters. The new design addresses the trade-off between increasing output voltage levels to reduce harmonics and the consequent rise in device count. The proposed topology is streamlined, consisting of 12 switches, 3 capacitors, 2 diodes, and a single DC source. Comparative analysis with similar topologies confirms the advantages of the new design. The experimental results show that the proposed inverter achieves a THD of 13.58% in its output voltage. The topology is validated through its application in a single-stage, three-phase photovoltaic system connected to the grid. Simulations are conducted using MATLAB/Simulink to test the system's performance. Furthermore, hardware-in-the-loop experiments are performed using OPAL-RT 5700 real-time simulators to further substantiate the efficacy of the proposed topology.