Three-Leg Quasi-Z-Source Inverter with Input Ripple Suppression for Renewable Energy Application

Single-phase inverters are widely employed in renewable energy applications. However, their inherent 2ω-ripple power can substantially affect system performance, leading to fluctuations the maximum points (MPP) of photovoltaic (PV) systems and shortening lifespans fuel cell (FC) systems. To alleviate input ripple, a three-leg quasi-Z-source inverter (QZSI) its associated control strategy proposed. The QZSI consists network, an H-Bridge inverter, active filter (APF). filtering structure comprises capacitors third bridge leg. proposed three loops: open-loop simple boost control, output voltage suppression control. Open-loop is utilized for shoot-through state modulation, applied two bridge-legs H-Bridge, additional bridge-leg adopts quasi-PR (QPR) method that injects specific frequency harmonic suppresses newly generated low-frequency components current. This effectively avoids drawbacks utilizing passive strategies, such as high-value impedance networks, low density, weak stability. A simulation platform 300W 144VDC/110VAC50Hz constructed. results indicate addition leg under full load conditions reduces input-side inductor current ripple ΔI from 1.89 with 0.513 A, representing reduction 72.86%. second reduced 18.2% 4.5%, fourth 16.5% 2.1%. DC bus ΔVPN falls 70.75 V 6.54 V, 90.76%. Total Harmonic Distortion (THD) both less than 1%. validated feasibility approach.