Modular Multilevel Converters: Technologies, Control and Applications

Dear Colleagues,

Modular multilevel converters (MMCs) have become one of the most significant converter topologies in modern power electronics, thanks to their modular architecture, high efficiency, superior harmonic performance, and excellent scalability for medium- and high-voltage applications. As a result, MMCs are widely implemented in high-voltage direct current (HVDC) transmission systems, medium- and high-voltage motor drives, energy storage interfaces, renewable energy systems, and power quality enhancement applications. They play a pivotal role in advancing flexible and reliable power conversion solutions.

As MMC-based systems continue to evolve toward higher power ratings and more diverse application domains, several technical challenges have garnered growing attention from the research community. These include the development of novel multilevel converter topologies that offer enhanced efficiency and power density, effective management of internal dynamics such as submodule capacitor voltage balancing and circulating current suppression, advanced modulation and switching strategies tailored for various operating conditions, and robust fault diagnosis, protection, and fault-tolerant control under abnormal scenarios.

In addition, there is an increasing demand for MMCs to deliver multifunctional grid-support services beyond conventional power conversion. Such services include harmonic mitigation, reactive power compensation, voltage regulation, and mitigation of unbalanced grid conditions. These requirements drive further investigation into modelling, control design, and application-oriented optimization of MMCs in HVDC systems, electric drives, and renewable energy integration. Comprehensive methodologies for modelling, simulation, and experimental validation are also essential to support these advancements.

This Special Issue aims to present and disseminate the latest breakthroughs in the technology, control methods, and applications of modular multilevel converters. It provides a dedicated forum for researchers and industry practitioners to share original research contributions and in-depth review articles addressing both theoretical foundations and practical implementations of MMC-based systems.

Topics of interest for publication include, but are not limited to, the following:

• Novel multilevel topologies with high efficiency and high power density;
• Advanced modulation and switching strategies for MMCs under different performance requirements (e.g., efficiency, harmonic suppression, scalability);
• Capacitor voltage balancing and energy management techniques in MMCs;
• Circulating current modelling, analysis, and control methods;
• Advanced modelling approaches;
• Fault diagnosis, fault protection, and fault tolerance techniques for MMC-based systems;
• Application of multilevel inverters in electric drive;
• Application of multilevel inverters in HVDC transmission and multiterminal DC grids;
• Application of multilevel inverters in wind, photovoltaic, and energy storage;
• MMC-based solutions for power quality improvement, including harmonic suppression, unbalance mitigation, reactive power compensation, and voltage support;
• Modelling, simulation, and experimental validation techniques for MMC-based power electronic systems.

Prof. Dr. Jinyu Wang
Dr. Tan Li
Dr. Zhijie Liu
Guest Editors

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