A Novel Harmonic Control Method for MMC Combining Improved Nearest Level Control and Selective Harmonic Elimination method

Yu Jin, Songda Wang, Qian Xiao*, Yiqi Liu, Yunfei Mu, Yanchao Ji, Sanjay K. Chaudhary, Remus Teodorescu

*Corresponding author

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review


This paper proposes a novel harmonic control method combining the improved nearest level control (NLC) and selective harmonic elimination (SHE) method. For the proposed improved NLC, it is applied on the voltage reference of the output terminals instead of the voltage reference of each arm. It has the advantages of higher control accuracy and better harmonic performance especially for the medium voltage application where the number of submodule (SM) is not high. For SHE method, it is applied in this paper to eliminate one certain harmonic by adding an additional signal pulse in each quarter wave. By combination of the two methods, one certain undesired harmonic can be eliminated while maintaining the low switching frequency of NLC. In addition, a novel hysteresis circulating current controller is introduced in this paper, which can control the circulating current, and then effectively regulate the arm energy. Compared with conventional NLC method, the proposed method provides a better harmonic performance and eliminates one certain harmonic at the price of slightly increase of the switching frequency. Moreover, since only one SHE pulse is added in a quarter wave, the additional SHE angles can be directly calculated by equation and do not require other optimal algorithm. Therefore, it can be applied online with variable modulation index. Taking the fifth order harmonic as an example, the simulation results verify the effectiveness of the proposed harmonic control method.

Original languageEnglish
Title of host publication2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019
Number of pages8
Publication dateSep 2019
Article number8912529
ISBN (Electronic)9781728103952
Publication statusPublished - Sep 2019
Event11th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2019 - Baltimore, United States
Duration: 29 Sep 20193 Oct 2019


Conference11th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2019
CountryUnited States
SponsorIEEE Industry Application Society (IAS), IEEE Power Electronics Society (PELS)
SeriesIEEE Energy Conversion Congress and Exposition

Bibliographical note

Funding Information:
ACKNOWLEDGMENT This paper would like to thank the Chinese Scholarship Council for its foundation for the research in Aalborg university, Denmark.

Funding Information:
This work is also supported in part by the National Key Research and Development Program of China (Grant no. 2017YFB0903300), the project of National Natural Science Foundation of China (Grant Nos. 51625702, and 51807135), and the Joint Fund Project of National Natural Science Foundation-State Grid Corporation (Grant no. U1766210).

Publisher Copyright:
© 2019 IEEE.

Copyright 2020 Elsevier B.V., All rights reserved.


  • Circulating current control
  • Harmonic control
  • Hysteresis control
  • Modular multilevel converter (MMC)
  • Nearest level control (NLC)
  • Selective harmonic elimination (SHE)

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