PV-Grid System in Mismatch Operating Mode: Improvement Through a New Voltage Balancing Method in Multilevel NPC Inverters

In this paper a balancing control of the dc input voltage of a 3-Level and 5-Level Neutral Point Clamped Inverters (3L-npc and 5L-npc) is proposed. In renewable applications and injection to AC bus, are often used boost converters and inverter. The proposed control allows independent MPPT for each source in a Distributed-MPPT (DMPPT) configuration. It is known that the DMMPT offers improvements in annual energy compared to a Centralized-MPPT (CMPPT). A model for current in neutral point is proposed for 3L-npc. Furthermore, a generalization of balancing algorithm for 5L-npc is presented. The local stability of the balancing is ensured. The effectiveness is validated by simulations and experimental results.