A Modular Multilevel Series/Parallel Converter for a Wide Frequency Range Operation


Journal Article

© 1986-2012 IEEE. When providing ac output, modular multilevel converters (MMCs) experience power fluctuation in the phase arms. The power fluctuation causes voltage ripple on the module capacitors, which grows with the output power and inversely to the output frequency. Thus, low-frequency operations of MMCs, e.g., for motor drives, require injecting common-mode voltages and circulating currents, and strict dc voltage output relative to ground is impossible. To address this problem, this paper introduces a novel module topology that allows parallel module connectivity in addition to the series and bypass states. The parallel state directly transfers power across the modules and arms to cancel the power fluctuations and hence suppresses the capacitor voltage ripple. The proposed series/parallel converter can operate at a wide frequency range down to dc without common-mode voltages or circulating currents; it also allows sensorless operation and full utilization of the components at higher output frequencies. We present detailed simulation and experiment results to characterize the advantages and limitations of the proposed solution.

Full Text

Duke Authors

Cited Authors

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

Published Date

  • October 1, 2019

Published In

Volume / Issue

  • 34 / 10

Start / End Page

  • 9854 - 9865

International Standard Serial Number (ISSN)

  • 0885-8993

Digital Object Identifier (DOI)

  • 10.1109/TPEL.2019.2891052

Citation Source

  • Scopus