Quantifying the Impact of Frequency and Modulation Index on the Performance of a Modular Multilevel Converter

The Modular Multilevel Converter (MMC) has emerged as a prominent technology for high-power and medium/high-voltage applications due to numerous advantages such as easy scalability, reduced harmonics, improved efficiency, fault-tolerant operation and enhanced controllability. This paper presents a thorough investigation into the comparative performance of the MMC across different frequencies and amplitude modulation indices (Ma). The study provides valuable insights into the behavior of the converter under diverse operating conditions by focusing on key parameters such as submodule (SM) capacitor voltages ripples, circulating currents, line currents, phase voltages and line voltages. The frequency of operation is a critical factor influencing the performance of power electronic converters. This research systematically explores the impact of varying frequencies on the MMC's operation, considering both low- and fundamental-frequency conditions. The analysis includes an in-depth examination of SM capacitor voltage ripples and circulating currents among others under various frequency operations. Amplitude modulation index, a parameter that significantly affects the quality of output waveforms in MMC, is varied to assess its impact on the converter's performance. The study investigates the influence of different Ma on SM capacitor voltage ripples, and circulating currents. By examining these parameters, the paper aims to provide a comprehensive understanding of how frequency along with Ma influences the overall performance of the MMC. The comparative analysis across different frequencies and Ma offers valuable insights into the converter's performance under varying conditions. By providing deeper insights into MMC behavior, this work enables better understanding of MMC operation.