Design and operation of a hybrid modular multilevel converter

Rong Zeng, Lie Xu, Liangzhong Yao, Barry W. Williams

Research output: Contribution to journalArticle

255 Citations (Scopus)
678 Downloads (Pure)

Abstract

This paper presents a hybrid modular multilevel converter (MMC), which combines full-bridge submodules (FBSM) and half-bridge submodules (HBSM). Compared with the FBSM-based MMC, the proposed topology has the same dc fault blocking capability but uses fewer power devices hence has lower power losses. To increase power transmission capability of the proposed hybrid MMC, negative voltage states of the FBSMs are adopted to extend the output voltage range. The optimal ratio of FBSMs and HBSMs, and the number of FBSMs generating a negative voltage state are calculated to ensure successful dc fault blocking and capacitor voltage balancing. Equivalent circuits of each arm consisting of two individual voltage sources are proposed and two-stage selecting and sorting algorithms for ensuring capacitor voltage balancing are developed. Comparative studies for different circuit configurations show excellent performance balance for the proposed hybrid MMC, when considering dc fault blocking capability, power losses, and device utilization. Experimental results during normal operation and dc fault conditions demonstrate feasibility and validity the proposed hybrid MMC.

Original languageEnglish
Article number6807785
Pages (from-to)1137-1146
Number of pages10
JournalIEEE Transactions on Power Electronics
Volume30
Issue number3
Early online date29 Apr 2014
DOIs
Publication statusPublished - 14 Oct 2014

Keywords

  • DC fault
  • hybrid
  • modular multilevel converter (MMC)
  • power losses
  • voltage ripple
  • full-bridge submodules
  • FBSM
  • half-bridge submodules
  • HBSM
  • MMC

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