On the Robust Control of DC-DC Converters: Application to a Hybrid Power Generation System

International audienceIn this paper a complete robust control synthesis is performed for a hybrid power generation structure composed by a Fuel Cell and a Supercapacitor. The control strategies are applied to the DC-DC boost power converters associated to each power source. Multivariable PI control with H∞ performance, H∞ full and reduced order controllers are designed and compared. The multivariable PI controller is designed through an optimization procedure based on solving some Linear Matrix Inequalities. A μ-analysis and frequency/time response performances results shows the advantages of the different proposed control strategies

Robust Control Analysis using Real-Time Implementation of a Hybrid Fuel Cell Power Generation System

International audienceIn this paper a complete robustness analysis is performed for a hybrid Fuel Cell/Supercapacitor generation system with power management, realized through the control of two identical boost power converters. For the closed-loop control a previously proposed multivariable robust control is considered. The robust control strategy analyzed consists of a multivariable Proportional-Integral controller found using an algorithm with a Linear Matrix Inequalities (LMI) formulation proposed by the authors in former works. The control actuators are the duty cycles of the boost power converters interfacing the Fuel Cell (FC) and the Supercapacitor (SC) with the system electrical load. The control effectively achieves stability and performance robustness for several considered parameter variations sets. Simulation results were obtained using µ-analysis theory and the experimental validation was achieved. The results obtained show the improvement of the system robustness with a strategy that can be generalized as a robust control methodology

Robust Optimal Control Strategies for a Hybrid Fuel Cell Power Management System

International audienceAbstract--In this paper several optimal control strategies are proposed for the power management subsystem of a hybrid fuel cell/supercapacitor power generation system. The control strategies are based on different control configurations involving the power converters associated to the hybrid source. Given certain desired performances, Linear Matrix Inequalities methods are used to solve the controller design problem that is written as an optimization problem with inequalities constraints. The solution to the optimization problem yields a simple PID controller with H∞ desired performance. For the several control strategies proposed, robustness is a primary issue. Time simulations and robustness analysis shows the effectiveness of the proposed strategies when compared with the classic control strategies used for this type of hybrid power generation system

Compact infrared cryogenic wafer-level camera: design and experimental validation

International audienceWe present a compact infrared cryogenic multichannel camera with a wide field of view equal to 120 degrees. By merging the optics with the detector, the concept is compatible with both cryogenic constraints and wafer-level fabrication. The design strategy of such a camera is described, as well as its fabrication and integration process. Its characterization has been carried out in terms of the modulation transfer function and the noise equivalent temperature difference (NETD). The optical system is limited by the diffraction. By cooling the optics, we achieve a very low NETD equal to 15 mK compared with traditional infrared cameras. A postprocessing algorithm that aims at reconstructing a well-sampled image from the set of undersampled raw subimages produced by the camera is proposed and validated on experimental images. (C) 2012 Optical Society of Americ

Estimation fo genetic parameters and genome scan for QTL influencing male fertility, semen production and semen quality of dairy bulls

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Détection de dysfonctionnements d'une pile à combustible PEMFC à partir de sauts de courant

International audienceL'objectif est de montrer qu'il est possible de détecter certains dysfonctionnements à partir de mesures de saut de courant. Un modèle obtenu à partir de la méthode de la spectroscopie d'impédance a été adapté à l'utilisation en saut de courant. La démarche proposée est basée sur l'estimation des paramètres du modèle. Le filtre de Kalman étendu paraît bien adapté mais il nécessite une série de sauts et interruptions de courant. Nous avons simulé l'effet de la dégradation de la couche active sur les paramètres, puis détecté ces variations sur les mesures réelles, montrant un vieillissement probable des couches actives

Stratégies d’utilisation de bio hydrogène pour la technologie PEMFC : Utilisation directe, purification, compression.

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Biohydrogen utilization strategies for PEMFC technology

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Failure detection in PEM fuel cells for diagnosis

National audienceIn this paper, two approaches for PEM fuel cell diagnosis are explored. Both use non-invasive measurements. The first to be studied is fuel cell response to current step excitation, which can occur at startup or shutdown of the fuel cells. This approach leads to diagnostic methods based on models of cell and parametric estimation. The second approach is based on magnetic field measurements. These measurements are representative of current distribution inside the fuel cell stack. Magnetic field is measured by a set of 24 sensors placed in a circle around the middle of the stack. Their location allows detecting inhomogeneities in current density distribution. This approach leads to diagnostic methods based on magnetic signatures that are defined for low air stoichiometric ratio and low humidity of gas. The first approach has been applied to 8-cells PEM fuel cell stack with new cells and after six months of use. The evolution of the model's parameter due to aging could be attributed to the degradation of the active layers. In the second approach, the magnetic signatures corresponding to low air stoechiometric ratio and magnetic signature of low humidity of gas have been characterized. Therefore, these two approaches are complementary. To detect aging damage, diagnosis by current step allows observing time evolution due to aging of the model parameters. To detect a change in the operation mode, it is preferable to use a non-active measurement. That is why the diagnosis by magnetic field seems more appropriate