Self-Balanced Switched Capacitor-Based Common Ground Five Level Quad Boost Inverter for Grid Connected Renewable Energy Application

Abstract

Leakage current and buck behavior are common problems nowadays for PV (photovoltaic) inverters intended for transformerless operation in grid-connected applications. To address these issues, this work presents a novel inverter configuration based on a common-ground switched-capacitor (SC) structure. The proposed inverter provides a fourfold voltage-boosting capability while generating a five-level output waveform without leakage current. Two SC cells enhance the PV input voltage and enable single-stage voltage boosting. The inverter also supports both leading and lagging power-factor operation with reactive-power transfer between the PV inverter and grid. The proposed modulation scheme maintains the capacitor voltages around their rated values without requiring additional voltage-balancing sensors or feedback regulation. Experimental results demonstrate a grid-current THD of 3% under unity-power-factor operation and 3.67% when the grid voltage is reduced from 1 p.u. to 0.8 p.u. The grid current remains stable within one grid-voltage cycle during the voltage-sag condition. Furthermore, the PLECS-based loss and efficiency analysis shows a maximum efficiency of 98.25% at 50 W, with efficiency remaining above 95.54% from 50 W to 1 kW. These results demonstrate the effectiveness and practical feasibility of the proposed common-ground five-level quad-boost inverter for transformerless grid-connected PV applications.