A Switched-Capacitor Based Single-Phase Transformerless Inverter for Grid Integration

Abstract

Transformerless grid-connected inverters are gaining popularity due to their high efficiency, compact design, and cost-effectiveness than transformer-based inverters. However, these inverters face significant challenges, particularly leakage current and limited voltage boost capability. This paper presents a novel solution to these issues through a five-level transformerless inverter (TLI) topology utilizing switched capacitors (SCs). The inverter utilizes seven insulated gate bipolar transistors (IGBTs), two diodes, and two SCs to achieve a five-level boosted output while ensuring low leakage current. Near-zero leakage current is enabled by maintaining a constant common mode voltage (CMV). Finite control set model predictive control (FCS-MPC), instead of traditional modulators, facilitates grid current tracking and reduced current harmonics. The use of only seven switches and two SCs results in increased efficiency and reduced losses. Comprehensive MATLAB/Simulink simulations and an experimental prototype validate the effectiveness of the proposed TLI for solar PV integration.