Module implementation and modulation strategy for sensorless balancing in modular multilevel converters


Journal Article

© 1986-2012 IEEE. Modules with series and parallel connectivity add new features and operation modes to modular multilevel converters (MMCs). Compared to full-and half-bridges, the series/parallel modules allow sensorless module balancing and reduce conduction loss with the same semiconductor area. However, in high-voltage applications with limited switching rates, the sensorless operation of the series/parallel modules suffers from large charge-balancing currents. This paper introduces a series/parallel module variant with a small port inductor. The port inductor suppresses the charge-balancing current despite low switching rates. We also propose a carrier-based modulation framework and show the importance of the carrier assignment in terms of efficiency and balancing. The proposed module and the modulation method are verified on a lab setup with module switching rates down to 200 Hz. The module voltages are kept within a narrow band with the charge-balancing currents below 5% of the arm current. The experimental results show practicality and advantages of the new series/parallel modules in high-voltage MMC applications.

Full Text

Duke Authors

Cited Authors

  • Li, Z; Lizana, R; Sha, S; Yu, Z; Peterchev, AV; Goetz, SM

Published Date

  • September 1, 2019

Published In

Volume / Issue

  • 34 / 9

Start / End Page

  • 8405 - 8416

International Standard Serial Number (ISSN)

  • 0885-8993

Digital Object Identifier (DOI)

  • 10.1109/TPEL.2018.2886147

Citation Source

  • Scopus