Modular Cascaded H-Bridge Multilevel Inverter with Distributed MPPT for Grid Connected Application

Abstract

This work presents a modular cascaded H-bridge multilevel photovoltaic (PV) inverter for three-phase grid-connected applications. The topology of modular cascaded H-Bridge multilevel inverter helps to improve the efficiency and flexibility of PV systems. In this work, a distributed maximum power point tracking control scheme is applied for three-phase multilevel inverter to understand a better utilization of PV modules and maximize the solar energy extraction. Because this distributed MPPT control scheme allows independent control of each dc-link voltage. The mismatches in PV panel should takes place in three-phase gridconnected applications, and the above mentioned mismatches can be introduced unbalanced power supply, create an unbalanced grid current. PV mismatches can be controlled by the following technique i.e., a modulation compensation is introduced. By using nine H-bridge modules a three-phase seven-level cascaded H-bridge inverter is built, each phase has three modules. Simulation results are presented to verify the feasibility of the proposed approach.