Guo, J., Wang, X., Liang, Jun, Pang, H. and Goncalves, Jorge ![]() ![]() |
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Abstract
Due to the demand for high reliability, modular multilevel converters (MMCs) are designed with redundant sub-modules. Redundant sub-modules can be integrated into the converter by employing different redundancy schemes: the conventional active scheme, the load-sharing active scheme and the passive scheme. Different schemes have different impacts on the improvement of converter reliability. The contributions of this paper include that an analytical method is proposed to evaluate the reliability of MMCs under different redundancy schemes and the factors' influence on the converter reliability are analysed to determine the proper redundancy scheme. Reliability models of MMCs under different redundancy schemes are built using Markov chains and the recursive method. Based on the proposed models, the effects of redundant schemes are evaluated in terms of the converter reliability. A case study is conducted to validate the feasibility and robustness of proposed models and to specify the conditions in favour of each redundancy scheme. The benefits of sharing redundancy among arms are also explored from the reliability point of view. If IGBTs and capacitors are dominant components in a sub-module in terms of failure rates, the load-sharing active scheme performs better; otherwise, setting the redundant sub-modules in an idle state is more effective. It is also found that the number of required redundant sub-modules is greatly reduced by sharing redundancy among arms.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Engineering |
Publisher: | Institute of Electrical and Electronics Engineers |
ISSN: | 0885-8977 |
Date of First Compliant Deposit: | 1 August 2017 |
Date of Acceptance: | 7 June 2017 |
Last Modified: | 20 Sep 2023 21:31 |
URI: | https://orca.cardiff.ac.uk/id/eprint/103193 |
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