A Compact MMC Submodule Structure with Reduced Capacitor Size Using the Stacked Switched Capacitor Architecture

Yuan Tang, Minjie Chen, Li Ran

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Modular multilevel converters (MMCs) are being developed for the grid connection of offshore wind or tidal farms. In order to reduce the construction and maintenance costs, it is desirable to reduce the weight and volume of the system. In current MMC submodule designs, the reservoir capacitor usually accounts for over 50% of the total volume and 80% of weight. This paper presents a new design concept and control principle for a submodule using the stacked switched capacitor (SSC) architecture that can significantly reduce the capacitor size in an MMC. Practical considerations for a high-voltage high-power SSC-based MMC submodule are presented in this paper, through the design of a 21-level, 40-kV (pole-pole dc), 19.1-MW, grid-connected system, and the concept is demonstrated experimenttally on a scaled-down 400-V, 12.3-Apeak laboratory prototype submodule. It is shown that with the proposed SSC architecture, the total volume of capacitors in each submodule can be reduced by more than 40% without significantly increasing the power loss.

Original languageEnglish (US)
Article number7362232
Pages (from-to)6920-6936
Number of pages17
JournalIEEE Transactions on Power Electronics
Volume31
Issue number10
DOIs
StatePublished - Oct 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Keywords

  • Modular multilevel converter
  • submodule capacitor
  • switched capacitor circuits

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