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International audience; In this paper, a global study in terms of control architecture is applied to parallel voltage-source inverters. Parallelism of inverters represents very interesting advantages for the industrial applications to meet the high-power requirements, and it is possible to apply maintenance during the operation without interruptible operation. The main objective of this paper is to guarantee a reliable operation of the parallel inverters system during healthy and faulty conditions due to full disconnection of any inverter. Special precautions are recommended to avoid the negative effects of the circulating currents, which are caused essentially by the asynchronous pulse width modulation or existence of dispersion of the system component characteristics. To deal with this crucial problem, one-loop flatness-based control is proposed to the control of N parallel inverters and allows obtaining low total harmonic distortion. The proposed control uses the advantages of the flatness to ensure high power quality at the point of common coupling and equal currents distribution between the parallel inverters and minimize the impact of a full disconnection of any inverter on the performance. The proposed algorithm is theoretically analyzed and validated experimentally.

International audience; Multilevel inverters supplied by independent sources are increasingly studied to connect these sources to grid. One of the challenges is voltage balancing. Indeed, when supplying powers coming from renewable sources are different, the inverter input voltages are unbalanced. In this paper, a stable DC bus voltage balancing technique without modifying MPPT algorithm is presented. This allows an MPPT operating independently on each renewable source maximizing total absorbed power. In this work, the power topology includes two boost converters (one for each single source) and a 3-level Neutral Point Clamped (NPC) inverter. The boost converters are used to implement independent MPPT for each renewable source while the proposed voltage balancing is realized by modifying the inverter control. The main objective of this paper is to demonstrate the stability of the proposed technique. Simulation and experimental results confirm the effectiveness and the stability of the voltage balancing technique.

International audience; A voltage Balancing Control (BC) for the input voltage of a 3-level Neutral Point Clamped (3L-NPC) inverter is proposed. For renewable energy injection to AC grid, two independent sources are connected to the 3L-NPC via boost converters. The proposed BC allows independent MPPT for each source in a Distributed-MPPT (DMPPT). It is well known that the DMPPT offers 6.9-11.1% improvements in annual energy compared to a Centralized-MPPT (CMPPT). The stability of the proposed BC is analyzed and its effectiveness is validated by simulations and experimental results.

International audience; Cet article présente une nouvelle techniqued'équilibrage pour les tensions d'entrée d'un onduleur multiniveauxde type "Neutral Point Clamped (NPC)". Cette techniquepeut être utilisée dans des applications liées aux énergies renouvelables.Pour ces types d'applications, un onduleur classique2-niveaux est général utilisé, cependant lorsqu'il y a deuxsources, il est plus avantageux d'utiliser un onduleur NPC. Lesystème considéré dans ce travail est donc constitué de deuxsources photovoltaïques, deux convertisseurs DC/DC boost etun onduleur NPC connecté à un bus AC. Pour la définition dupoint de fonctionnement de chaque source, une stratégie de typeDistributed-MPPT(DMPPT) offre une amélioration du rendementénergétique annuel entre 6.9%-11.1% par rapport au Centralised-MPPT(CMPPT). En utilisant la technique d'équilibrage proposéeassociée à une configuration de type DMPPT, un MPPT indépendantpour les deux sources peut être obtenue pour une plus grandeplage de fonctionnement et ainsi augmenter l'efficacité énergétiqueannuelle globale de l'installation. Des résultats expérimentauxobtenus sur un banc de test du laboratoire permettent de validerles résultats de simulation et le modèle présentés dans cet article.