A novel single source three phase seven-level inverter topology for grid-tied photovoltaic application

Abstract

This paper presents a novel single-source three-phase multilevel inverter structure with voltage boosting capability, which is suitable for medium-voltage photovoltaic (PV) applications. The proposed structure consists of switched-capacitors (SCs) based multilevel dc-link stages that boost-up the input DC-source voltage significantly. It reduces the dc-link voltage requirements by 75% compared to the traditional neutral point clamped (NPC), flying capacitors (FCs), active NPC (ANPC), hybrid and hybrid clamped ANPC and cascaded h-bridge (CHB) topologies, and 50% compared to advanced ANPC topologies. The proposed structure also reduces the number of required switches and capacitors as well as their voltages stresses compared to these state-of-the-art topologies. A robust control scheme based on finite control set model predictive control (FCS-MPC) is derived to control the converter. The capacitor voltage balancing is inherent of the proposed topology, and thus, eliminates the need for additional voltage balancing circuit and reduces the control complexity.