Three-Phase Multilevel Inverters for LV Systems: Comparison of Modular Multilevel Converter and Flying Capacitor Structures

Abstract

The rapid growth of the penetration level of renewable energy sources in low-voltage (LV) networks increases the research interest in more efficient, compact, reliable, and easily expandable energy conversion devices. Thus, multilevel converters, a promising concept for dc-ac conversion, are gaining increased interest due to their smaller size relative to the conventional two-level structure. However, several issues related to the number of components and the added complexity cannot be ignored. To enrich the literature review concerning this topic, this work reviews and provides a comparative assessment of three state-of-the-art multilevel topologies for LV applications. This review considered three structures: state-of-the-art five-level modified MMC (5L-M-MMC), five-level flying capacitor using two three-level flying capacitor converters connected in parallel (2x3L-FC), and five-level flying capacitor (5L-FC). This comparative study is supported by simulation results based on a 10 kW system.