Multiscale Electrothermal Design of a Modular Multilevel Converter for Medium-Voltage Grid-Tied Applications

Xuhui Feng, Ramchandra Kotecha, Sreekant Narumanchi, Akanksha Singh, Barry Mather, Ke Wang, Boxue Hu, Jin Wang

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations


As a key feature of modular multilevel converters (MMCs), a large number of semiconductor devices are employed in the converter and distributed over a stack of submodules. Each submodule has a strict temperature limit that imposes constraints on the operating range of the converter. Different loading conditions/losses in the submodules lead to unavoidable temperature variations inside the MMC, which consequently affect the system-level performance and reliability. This paper is focused on the electrothermal analysis and design of a medium-voltage silicon carbide (SiC)-based MMC system, from submodule power semiconductors to the overall MMC system integration of multiple submodules, for grid-connected applications. Loss calculations are performed to estimate the cooling requirements and aid thermal design at different levels. The performance of a forced-air cooling approach is analyzed within a numerical modeling framework. Maximum temperature of the SiC power modules is predicted using numerical tools. Thermal design of the MMC cabinet with various arrangements of air inlet(s) and outlet(s) is investigated and compared from a cooling performance perspective. A fully resolved model of the arrangement that yields optimal results is developed to accurately predict the temperature profile of the essential components in the submodules.

Original languageAmerican English
Pages (from-to)3773-3784
Number of pages12
JournalIEEE Transactions on Industry Applications
Issue number3
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 1972-2012 IEEE.

NREL Publication Number

  • NREL/JA-5400-83362


  • Computational fluid dynamics (CFD)
  • electrothermal
  • heat transfer
  • modular multilevel converter
  • SiC


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