A T-type modular multilevel converter

Shuren Wang, Ahmed M. Massoud, Barry W. Williams

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This paper proposes a novel modular multilevel converter (MMC) named ‘T-type MMC’ (T-MMC) for reliable, controllable and efficient performance in energy conversion applications. Circuitry configurations and control structures are presented, with respect to fundamental and additional functions. The T-MMC topology consists of two solid-state power stages (Stage-I and Stage-II), which are coordinated for ac and dc fault tolerance, increased ac-side voltage synthesis, etc. Energy storage elements can be integrated into the submodules. As a result, the T-MMC based energy storage system can not only increase system inertia but maintain continuous power transmission during faults. A thyristor forced-commutation technique facilitates actively-controlled utilization of symmetrical thyristors in the conduction path; thus T-MMC normal-mode operation losses can be equivalent to those of the conventional half-bridge MMC. Simulation and experimentation demonstrate the performance of the T-MMC.
Original languageEnglish
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Early online date11 Nov 2019
Publication statusE-pub ahead of print - 11 Nov 2019



  • T-Type
  • modular multilevel converter
  • ac/dc fault
  • thyristor
  • energy storage system

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