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

Thumbnail Image



Journal Title

Journal ISSN

Volume Title

Repository Usage Stats


Citation Stats


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.





Published Version (Please cite this version)


Publication Info

Li, Z, F Ricardo Lizana, Z Yu, S Sha, AV Peterchev and SM Goetz (2019). A Modular Multilevel Series/Parallel Converter for a Wide Frequency Range Operation. IEEE Transactions on Power Electronics, 34(10). pp. 9854–9865. 10.1109/TPEL.2019.2891052 Retrieved from https://hdl.handle.net/10161/22567.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.



Stefan M Goetz

Assistant Professor in Psychiatry and Behavioral Sciences

Unless otherwise indicated, scholarly articles published by Duke faculty members are made available here with a CC-BY-NC (Creative Commons Attribution Non-Commercial) license, as enabled by the Duke Open Access Policy. If you wish to use the materials in ways not already permitted under CC-BY-NC, please consult the copyright owner. Other materials are made available here through the author’s grant of a non-exclusive license to make their work openly accessible.