A hybrid modular multilevel converter for medium-voltage variable-speed motor drives

Binbin Li, Shaoze Zhou, Dianguo Xu, Stephen J. Finney, Barry W. Williams

Research output: Contribution to journalArticlepeer-review

129 Citations (Scopus)
687 Downloads (Pure)


Modular multilevel converters (MMC) have revolutionized the voltage-sourced converter-based high-voltage direct current transmission, but not yet got widespread application in medium-voltage variable-speed motor drives, because of the large capacitor voltage ripples at low motor speeds. In this paper, a novel hybrid MMC topology is introduced, which significantly reduces the voltage ripple of capacitors, particularly at low motor speeds. Moreover, this topology does not introduce any motor common-mode voltage; as a result, there are no insulation and bearing current problems. Additionally, the current stress can remain at rated value throughout the whole speed range; thus, no device needs to be oversized and converter efficiency can be ensured. Operating principle of this hybrid topology is explained, and control schemes are also developed. Validity and performance of the proposed topology are verified by simulation and experimental results.
Original languageEnglish
Pages (from-to)4619 - 4630
Number of pages11
JournalIEEE Transactions on Power Electronics
Issue number6
Early online date4 Aug 2016
Publication statusPublished - 30 Jun 2017


  • capacitors
  • topology
  • integrated circuits
  • switches
  • converters
  • motor drives
  • DC motors


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