Modular Cascaded H-Bridge Multilevel PV Inverter With Distributed MPPT for Grid-Connected Applications

• Published in: IEEE transactions on industry applications Vol. 51; no. 2; pp. 1722 - 1731
• Main Authors: Bailu Xiao, Lijun Hang, Jun Mei, Riley, Cameron, Tolbert, Leon M., Ozpineci, Burak
• Format: Journal Article
• Language: English
• Published: IEEE 01-03-2015
• Subjects: Bridge circuits; Control systems; Inverters; Maximum power point trackers; Modulation; Topology; Voltage control; modulation compensation; Cascaded multilevel inverter; distributed maximum power point (MPP) tracking (MPPT); modular; photovoltaic (PV)
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2014.2354396

This paper presents a modular cascaded H-bridge multilevel photovoltaic (PV) inverter for single- or three-phase grid-connected applications. The modular cascaded multilevel topology helps to improve the efficiency and flexibility of PV systems. To realize better utilization of PV modules and maximize the solar energy extraction, a distributed maximum power point tracking control scheme is applied to both single- and three-phase multilevel inverters, which allows independent control of each dc-link voltage. For three-phase grid-connected applications, PV mismatches may introduce unbalanced supplied power, leading to unbalanced grid current. To solve this issue, a control scheme with modulation compensation is also proposed. An experimental three-phase seven-level cascaded H-bridge inverter has been built utilizing nine H-bridge modules (three modules per phase). Each H-bridge module is connected to a 185-W solar panel. Simulation and experimental results are presented to verify the feasibility of the proposed approach.