A simplified space vector modulation implementation for modular multilevel converter by grouping submodules

Autor: Zhihong Bai, Haoqi Chen, Yifei Li, Yinuo Dong, Hao Ma
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: IET Power Electronics, Vol 14, Iss 10, Pp 1725-1734 (2021)
Druh dokumentu: article
ISSN: 1755-4543
1755-4535
DOI: 10.1049/pel2.12086
Popis: Abstract Modulation strategy plays an important role in the good performance of modular multilevel converter (MMC). Since MMC has a special structure as well as a large number of submodules (SMs), it is almost impossible to apply the conventional multilevel space vector modulation (SVM) algorithm in it. In this study, a simplified SVM implementation method is proposed by grouping SMs. With the presented method, the high‐level SVM process for MMC can be easily done by implementing multiple two‐level or three‐level SVM algorithm, while the complicated offline or online efforts/tasks about mapping switching states or sequences in the conventional multilevel SVM are not necessary any more. In order to improve the harmonic characteristics, the sampling time of different subunits (SUs), each of which is formed by grouping a few SMs, is staggered evenly, which helps to achieve a higher equivalent switching frequency and less low‐order harmonics. Further, the capacitor voltage balance of SMs is improved by rotation strategies between SUs or inside each SU even without any capacitor voltage detecting or sorting. Since the presented method is independent of the number of SMs, it can be very easily expanded into a high‐level MMC. These propositions are verified by experiment.
Databáze: Directory of Open Access Journals
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