Super-Twisting Based Sliding Mode Control of a Single-Phase Grid-Connected Transformerless Inverter for PV Systems With Leakage Current Reduction

Abstract

The growing adoption of photovoltaic energy has increased the use of grid-connected inverter systems, particularly transformerless inverters, due to their cost-effectiveness and high efficiency. However, these inverters face a persistent challenge in managing leakage current, which can compromise both safety and grid current quality. Thus, effective grid current control and leakage current minimization are essential for enhancing system performance and safety. This study investigates a transformerless grid-connected H-bridge neutral point clamped inverter, focusing on leakage current reduction. A super-twisting algorithm-based sliding mode control is proposed for grid current regulation, enhanced by a modified modulation scheme, symmetric filter design, and optimized control structure. MATLAB/Simulink simulations validated the system's design and control strategy, demonstrating effective grid current regulation and significant leakage current reduction.