A Critical Review on Hybrid-Topologies, Modulation Techniques, and Controlling Approaches of Modular Multilevel Converter for Grid Integration

Applications such as high-voltage direct current (HVDC) transmission networks, flexible alternating current power transmission (FACTS), medium voltage (MV) motor drives, and power performance improvement topologies all see significant growth in demand for modular multilevel converters (MMCs) due to their attractive features. A 3-phase MMC can be described as having an AC terminal, a DC terminal, and a kernel for conversion with three-phase legs as part of its basic configuration. Each phase/leg in an MMC is having two symmetrical arms referred to as lower and upper arms. In order to reduce the high-frequency content in the arm currents, all the submodules are coupled in series with chock inductor. Now a days, the use of MMC is widespread because of its competitive benefits includes superior output performance, high modularity, simple scaling, and minimal voltage and current rating requirements for the power switches. A lot of work is being done around the world to find ways to use it in photovoltaic (PV) applications, low/medium voltage drives, converting wind energy and other places. In this paper, a detailed review of MMC is given, including its topological variants, modulation methods, modeling and capacitor voltage balancing techniques, fault-tolerant behavior, controlling approaches and future trends and challenges.