Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters
Nearest-level control (NLC) is a popular technique used in modular multilevel converters (MMCs) with a large number of submodules (SMs) owing to the NLC's flexibility and ease of implementation. However, in medium-voltage applications, MMCs contain a relatively low number of SMs, and the drawba...
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| Format: | Article |
| Language: | English |
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IEEE
2020-01-01
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| Series: | IEEE Access |
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| Online Access: | https://ieeexplore.ieee.org/document/9114885/ |
| _version_ | 1818921069937950720 |
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| author | Minh Hoang Nguyen Sangshin Kwak |
| author_facet | Minh Hoang Nguyen Sangshin Kwak |
| author_sort | Minh Hoang Nguyen |
| collection | DOAJ |
| description | Nearest-level control (NLC) is a popular technique used in modular multilevel converters (MMCs) with a large number of submodules (SMs) owing to the NLC's flexibility and ease of implementation. However, in medium-voltage applications, MMCs contain a relatively low number of SMs, and the drawbacks of the NLC methods emerge, wherein the poor quality of output voltages and currents result in high total harmonic distortion, large ripples in SM capacitor voltages, and unsuppressed circulating currents. Several NLC methods have been proposed to handle these problems, but they do not satisfy all the control objectives simultaneously. This paper proposed a modified NLC capable of enhancing the output quality of MMCs with low number of SMs without deteriorating the control objectives. Unlike previously reported NLC methods, instead of directly calculating the numbers of SMs from the upper and lower arm voltage references, the difference and total number of SMs are obtained from the output voltage reference and circulating current control, respectively. Hence, the numbers of SMs in the upper and lower arms are acquired by simply solving a system of first-order two-variable equations. The simulated and experimental results for a single-phase MMC system were used to verify the appropriateness and effectiveness of the proposed modified NLC method. |
| first_indexed | 2024-12-20T01:31:47Z |
| format | Article |
| id | doaj.art-bc002c0586e14acfbdb1c0e0a1eac0f9 |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-12-20T01:31:47Z |
| publishDate | 2020-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-bc002c0586e14acfbdb1c0e0a1eac0f92022-12-21T19:58:05ZengIEEEIEEE Access2169-35362020-01-01811023711025010.1109/ACCESS.2020.30015879114885Nearest-Level Control Method With Improved Output Quality for Modular Multilevel ConvertersMinh Hoang Nguyen0https://orcid.org/0000-0003-1784-0842Sangshin Kwak1https://orcid.org/0000-0002-2890-906XSchool of Electrical and Electronics Engineering, Chung-Ang University, Seoul, South KoreaSchool of Electrical and Electronics Engineering, Chung-Ang University, Seoul, South KoreaNearest-level control (NLC) is a popular technique used in modular multilevel converters (MMCs) with a large number of submodules (SMs) owing to the NLC's flexibility and ease of implementation. However, in medium-voltage applications, MMCs contain a relatively low number of SMs, and the drawbacks of the NLC methods emerge, wherein the poor quality of output voltages and currents result in high total harmonic distortion, large ripples in SM capacitor voltages, and unsuppressed circulating currents. Several NLC methods have been proposed to handle these problems, but they do not satisfy all the control objectives simultaneously. This paper proposed a modified NLC capable of enhancing the output quality of MMCs with low number of SMs without deteriorating the control objectives. Unlike previously reported NLC methods, instead of directly calculating the numbers of SMs from the upper and lower arm voltage references, the difference and total number of SMs are obtained from the output voltage reference and circulating current control, respectively. Hence, the numbers of SMs in the upper and lower arms are acquired by simply solving a system of first-order two-variable equations. The simulated and experimental results for a single-phase MMC system were used to verify the appropriateness and effectiveness of the proposed modified NLC method.https://ieeexplore.ieee.org/document/9114885/Nearest-level controlmodular multilevel converterincrease level numberoutput voltage qualitycirculating current |
| spellingShingle | Minh Hoang Nguyen Sangshin Kwak Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters IEEE Access Nearest-level control modular multilevel converter increase level number output voltage quality circulating current |
| title | Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters |
| title_full | Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters |
| title_fullStr | Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters |
| title_full_unstemmed | Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters |
| title_short | Nearest-Level Control Method With Improved Output Quality for Modular Multilevel Converters |
| title_sort | nearest level control method with improved output quality for modular multilevel converters |
| topic | Nearest-level control modular multilevel converter increase level number output voltage quality circulating current |
| url | https://ieeexplore.ieee.org/document/9114885/ |
| work_keys_str_mv | AT minhhoangnguyen nearestlevelcontrolmethodwithimprovedoutputqualityformodularmultilevelconverters AT sangshinkwak nearestlevelcontrolmethodwithimprovedoutputqualityformodularmultilevelconverters |