Inrush Current Minimization in Reduced Device Count Multilevel Inverter Interfacing PV System

Abstract

Switched capacitor (SC) based multilevel inverters (MLIs) are evolving rapidly for varieties of dc-ac power conversion applications. This is due to the voltage balancing ability without any complicated control circuit and voltage boosting ability. Even with these major advantages of SC topologies, a key issue in these circuits is the high inrush current while sudden charging and discharging of capacitors. This issue has been addressed in this work by proposing a new SCMLI circuit consisting lower number of switches and a single source. The merits of the proposed circuit such as voltage balancing of capacitors without adding closed loop control, voltage boosting and single source requirements has motivated the authors to employ the same circuit in photovoltaic (PV) application. The proposed SCMLI is interfaced with the PV systems through dc-dc boost converter. The dc-dc boost converter allows voltage boosting additional to the boosting capability of SC network and assist in minimizing the inrush current due to presence of inductor. The advantages of the proposed structure are verified by a detailed comparison with existing configurations and extensive simulation study of the proposed circuit in integration with the PV system.