A switched-capacitor cell-based single-phase five-level solar photovoltaic inverter with common-ground integration for zero-leakage grid connection

Abstract

Aligned with the appreciation for transformerless inverters in solar photovoltaic (PV) systems connected to a single-phase grid, the transition toward multilevel structures enhances performance with staircase-shaped output profiles. At the same time, the persistent challenge of ground leakage currents from PV parasitic capacitances drives ongoing structural innovations. To address the aforementioned issue, this study proposes an innovative single-phase common-grounded five-level inverter design. It utilizes the switched-capacitor (SC) technique to generate a stepped output voltage from a single DC source while effectively bridging PV-related parasitic capacitors to ensure zero leakage current. The proposed inverter integrates a series-parallel switching mechanism into the SC single-cell, enabling the self-balancing synthesis of voltage levels for both incomplete and complete five-level voltage types. The developed inverter’s capabilities are validated using MATLAB/Simulink for electrical performance, PSIM for temperature-dependent losses, and experimental tests for functionality and feasibility.