A Quasi-Switched Capacitor Based Grid-Connected PV Inverter With Minimum Leakage Current

Abstract

This article proposes a single-stage quasi-switched capacitor based five-level inverter (qSB-5LI) for photo voltaic (PV) systems. The proposed topology comprises dual quasi-Z-source (qZS) networks and switched capacitor based f ive-level inverter with a single PV source. A modified modulation technique based on level-shifted PWM (LSPWM) is implemented to achieve voltage boosting and five-level inversion. Furthermore, the proposed topology achieves a higher boost factor in compar ison to the existing qZS-fed five-level topologies in the literature. The steady-state and dynamic performances of the qSB-5LI with closed-loop control schemes in both stand-alone mode and grid connection mode of operation are demonstrated. In addition, the proposed topology results in a reduced leakage current complying with the VDE0126-1-1 standard. Moreover, the proposed topology eliminates the requirement of any external LCL filter to reduce the leakage current. The principle of the power converter is verified with an experimental prototype in both stand-alone and grid-connection modes of operation.