A Hybrid Nine-Arm Modular Multilevel Converter for Medium-Voltage Six-Phase Machine Drives

Mohamed S. Diab*, Ahmed A. Elserougi, Ahmed M. Massoud, Shehab Ahmed, Barry W. Williams

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

18 Citations (Scopus)


The nine-arm modular multilevel converter (9A-MMC) has been recently proposed as a reduced MMC topology variation for six-phase drive applications, with 25% reduction in the number of employed arms and associated components, compared to a standard dual three-phase MMC, however with a limited output voltage amplitude. This paper proposes a hybrid 9A-MMC comprised of half-bridge submodules (SMs) in both the upper and lower arms, and full-bridge SMs in the middle arms. By employing the negative-voltage state of the full-bridge SMs, the hybrid 9A-MMC avoids the limitations imposed on the dc-link voltage utilization, while achieving further reduction in the component count, compared to a standard 9A-MMC with identical half-bridge SMs. The operating principles of the proposed hybrid 9A-MMC are illustrated with mathematical analysis, whereas its characteristics are verified through both simulation and experimentation. An assessment of the proposed topology quantifying its employed components is also provided, in comparison to other MMC-based six-phase machine drives.

Original languageEnglish
Article number8536864
Pages (from-to)6681-6691
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Issue number9
Publication statusPublished - 15 Nov 2018

Bibliographical note

The acceptance date for this record is provisional and based upon the month of publication for the article.


  • Hybrid modular multilevel converter (MMC)
  • medium-voltage (MV) machine drive
  • nine-arm MMC
  • six-phase machines


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