Comparative analysis of principal modulation techniques for modular multilevel converter and a modified reduced switching frequency algorithm for nearest level pulse width modulation

• Datum: 2025
• Hauptverfasser: Benboukous, M., Bahri, H., Talea, M., Bour, M., Abdouni, K.
• Format: Artikel
• Sprache: English
• Veröffentlicht: National Technical University "Kharkiv Polytechnic Institute" and Аnatolii Pidhornyi Institute of Power Machines and Systems of NAS of Ukraine 2025
• Schlagworte: modular multilevel converter; level-shifted pulse width modulation; nearest level control; nearest level pulse width modulation; capacitor voltage balancing; reduced switching frequency
• Online Zugang: http://eie.khpi.edu.ua/article/view/320944
• Назва журналу: Electrical Engineering & Electromechanics

Introduction. The Modular Multilevel Converter (MMC) is an advanced topology widely used in medium and high-power applications, offering significant advantages over other multilevel converters, including high efficiency and superior output waveform quality. Problem. The modulation techniques and submodule capacitor voltage balancing significantly affect the performance of the MMC, influencing output voltage and current quality, capacitor voltage balancing, and power losses. Goal. This study presents a comparative analysis of 3 modulation techniques for a 3-phase MMC: Level-Shifted Pulse Width Modulation (LS-PWM), Nearest Level Control (NLC), and hybrid Nearest Level Pulse Width Modulation (NL-PWM). In addition, this study proposes a modification to the Reduced Switching Frequency (RSF) capacitor voltage balancing algorithm to adapt it for use with the NL-PWM technique. Methodology. The performance of each modulation technique is evaluated through simulations using MATLAB/Simulink software, in terms of output signal quality, capacitor voltage balancing, converter losses, and behavior under a line-to-ground fault. Results. The results show that both LS-PWM and NL-PWM generate lower harmonic content compared to NLC. However, the NLC technique presents the lowest switching losses, followed by NL-PWM and LS-PWM. The NL-PWM technique shows intermediate performance, making it more appropriate for medium-voltage applications. The results also confirm the proposed modifications to the RSF capacitor voltage balancing algorithm. Additionally, the LS-PWM technique shows greater robustness under fault conditions compared to the other techniques. Originality. For the first time, a comparative analysis of 3 modulation techniques for the MMC, LS-PWM, NLC, and NL-PWM has been conducted, highlighting their performance under different operating conditions. The study also proposes a modified RSF capacitor voltage balancing algorithm specifically for NL-PWM, which has not been previously explored in the literature. Practical value. The results of this study contribute to the selection of the most suitable modulation technique for MMC for specific applications. References 34, table 5, figures 17.