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Lookup NU author(s): Dr Mohamed Dahidah
This is the authors' accepted manuscript of an article that has been published in its final definitive form by IEEE, 2021.
For re-use rights please refer to the publisher's terms and conditions.
Modular multilevel converters have become the prominent topology for medium and high-voltage applications. The performance of these converters highly depends on the accuracy of the used modulation approach, for which the capacitor voltage of submodules (SM) are usually assumed to be equal. This paper exhibits that ignoring the capacitor voltage differences among SMs adversely affects the system performance. This becomes more obvious the larger the capacitor voltage differences are. Hence, this paper proposes a more accurate feedforward modulation approach that takes into account either the instantaneous capacitor voltage value and the real output voltage in the modulation stage. As a result, in applications where larger SM voltage differences are expected, the current distortion and control performance are improved. Particularly, switching-saving approaches benefit from this method as it enables their operation with reduced switching losses without the downsides of increased distortion due to capacitor voltage differences. The proposed approach is analyzed and compared with the nearest level modulation and with the level-shift PWM (LS-PWM). Simulations and experimental validation are presented to confirm the effectiveness of the proposed technique.
Author(s): Montero RP, Marquez AA, Dahidah MSA, Vazquez S, Leon JI, Konstantinou G, Garcia FL
Publication type: Article
Publication status: Published
Journal: IEEE Transactions on Power Electronics
Issue: ePub ahead of Print
Online publication date: 16/08/2021
Acceptance date: 07/08/2021
Date deposited: 09/08/2021
ISSN (print): 0885-8993
ISSN (electronic): 1941-0107
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