Engineering and Technology
| Open Access | Converter Employing Nearest Level Modulation Without Capacitor Voltage Sensing
Dr. Reza Karimi , Department of Electrical Engineering Institute of Advanced Engineering Technologies Tehran, Iran Dr. Nima Farhadi , Department of Mechanical and Industrial Engineering Center for Engineering Innovation and Technology Research Isfahan, IranAbstract
Modular Multilevel Converters (MMCs) have emerged as one of the most significant power electronic converter topologies for medium- and high-voltage applications due to their scalability, modularity, superior output waveform quality, and reduced harmonic distortion. Despite their advantages, conventional MMC control strategies typically depend on continuous capacitor voltage measurement for balancing energy among submodules. Such requirements increase system complexity, sensing costs, communication burden, and susceptibility to measurement inaccuracies. This study presents a comprehensive review and conceptual research framework for an advanced control strategy applied to a 21-level MMC employing Nearest Level Modulation (NLM) without direct capacitor voltage sensing. The proposed framework integrates modulation optimization, circulating current suppression, sensorless balancing mechanisms, and adaptive control principles to achieve stable converter operation while reducing hardware requirements. A detailed synthesis of existing MMC control approaches is conducted, emphasizing modulation methods, predictive control techniques, voltage balancing mechanisms, and renewable-energy-oriented MMC applications. Based on identified research gaps, a sensorless NLM-based control architecture is formulated and analyzed. The framework demonstrates how switching state selection, energy distribution estimation, and current-based balancing algorithms can maintain capacitor voltage equilibrium without dedicated voltage sensors. The study further discusses expected performance improvements in switching losses, harmonic quality, computational efficiency, reliability, and scalability. Findings indicate that sensorless NLM control can provide a practical and economically viable alternative for next-generation MMC systems deployed in smart grids, HVDC transmission, renewable energy integration, and industrial drive applications. The research contributes a structured theoretical foundation for future implementation and validation of advanced MMC control systems.
Keywords
Modular Multilevel Converter, Nearest Level Modulation, Sensorless Control, Capacitor Voltage Balancing
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Copyright (c) 2026 Dr. Reza Karimi, Dr. Nima Farhadi
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