Modular-Concatenated-Cell (MCC) Multilevel Converter: A Novel Circuit Topology and Innovative Logic-Equations-Based Control Technique

This paper introduces a new circuit topology for multilevel converters. The proposed multilevel converter circuitry is realized by the cascaded connection of a 2-level converter and modular-concatenated-cell (MCC) H-bridge cells. In the proposed MCC multilevel topology, the classic two-level converter functions as the main converter through generating the major voltage-steps, whereas auxiliary concatenated H-bridge cells produce the intermediate voltage-levels. The overall output voltage is formed by adding the intermediate voltage-levels to the major ones. The crucial distinction between the cascaded H-bridge (CHB) converters and proposed MCC multilevel converter topology is that the latter exploits flying-capacitors (FCs) instead of isolated dc-voltage sources, and uses per-phase redundant switching states to regulate FC voltages. The voltage rating of semiconductor power switches and FCs within the concatenated cells of the proposed MCC multilevel converter all are 1 p.u. that lead to a modular structure.