CReSTIC EA3804

The aim of this paper is to develop an accurate small signals model for a Boost converter operating in continuous conduction mode, and including the internal resistors of elements. This model is then used to synthesise a fuzzy logic controller that guarantees the output voltage regulation with desired performances. A comparative study illustrates the efficiency, the robustness and the flexibility of the proposed approach relatively to a classical PID controller.

The modeling process presents a key step on the analysis and the control of DC-DC converters that can exhibit complicated nonlinear phenomena. In order to describe accurately the converter behavior, a discrete modeling technique is proposed; it allows the exact description of the system with a minimum of simplifying assumptions and validity hypothesis of the mode. The validation of the proposed method is achieved through simulation and comparative study results using some criteria such as the approximation error, computing time and allocated memory for data processing and storage.

The occurrence of nonlinear phenomena in DC-DC power converters makes their analysis and control difficult. We propose a converter model that takes into account the internal resistances of the converter elements. A fuzzy logic controller is then used to shift the nonlinear phenomena outside the operating domain, and to ensure current regulation over a wide range of parameters. To validate the achieved performance, a comparative study is presented.

The minimum variance principle is, generally, used for controller's synthesis. In this paper, we propose another use of this principle to identify the hysteresis property of piezoelectric actuators using the Extended Least Squares identification technique adapted for the ARMAX model.

Grâce aux performances accrues des convertisseurs statiques, de nouveaux champs d'application se sont ouverts. Certains d'entre eux sont très exigeants en termes de performances dynamiques. Nous pouvons citer comme exemples la dépollution de réseaux électriques, l'alimentation de machines à courant alternatif pour des applications particulières, l'amplification de puissance (audio…). Pour de telles applications, il faudrait un convertisseur idéal, qui génèrerait une tension (ou un courant) de sortie rigoureusement identique à un signal de référence, à un facteur de proportionnalité près, y compris lorsque ce signal varie rapidement. Le transfert d'énergie entre la source et le récepteur serait alors idéalement contrôlé, la plage de fonctionnement serait la plus large possible sans entraîner l'apparition de phénomènes subharmoniques ou chaotiques. Pour cela, il faudrait être en mesure d'abord d'identifier, grâce à une modélisation adéquate, ces phénomènes indésirables. Ensuite, il est nécessaire d'optimiser la stratégie de commande, de manière à assurer une poursuite du signal de référence la meilleure possible, pour un convertisseur donné, commutant à une fréquence imposée par des limitations technologiques. Dans ce cadre que s'inscrit notre contribution dans ce travail de thèse. Un convertisseur statique de base est formé essentiellement de deux types de composants : i) électroniques de commutation (interrupteurs) ii) de stockage de l'énergie électrique (inductances, condensateurs). La conversion est effectuée en stockant l'énergie de la source durant une partie de la période de fonctionnement (d'horloge), puis transférée vers la charge pendant le reste de la période d'horloge; et ce graçe à une commande adéquate appliquée au niveau des interrupteurs. Afin d'assurer les performances désirées de ce transfert, un modèle mathématique du convertisseur permettant la synthèse du contrôleur est nécessaire. Parmi les modèles présentés [Gue, 06b], [Gue, 06c]. Structure du mémoire Ce mémoire comporte quatre chapitres : Dans le premier chapitre, nous introduisons le convertisseur statique ainsi que les principes de base pour l'analyse de son comportement. Ensuite, les différentes techniques de modélisation de ce système seront présentées avec leurs propriétés ainsi que leurs limites respectives. Afin de mieux appréhender les comportements non linéaires du convertisseur, quelques outils d'analyse nécessaires seront rappelés à la fin de ce chapitre. Dans le second chapitre, on s'intéressera à la technique de modélisation discrète des convertisseurs. Deux techniques largement utilisées dans la littérature [Ban, 01], [Tse, 03], seront analysées. Ensuite à partir de leurs inconvénients et de leurs limites, nous proposons d'introduire

In order to meet the requirements of harmonic elimination and reactive power compensation in substation, a three level four leg shunt active filter is proposed in this paper. The use of three-level converters allows a better performance of the equipment, by reducing harmonics and the ripple of the generated voltages and currents. The compensation algorithm is based on pqr theory. This scheme requires the service of a phased-locked loop (PLL) to make the system insensitive to the distortions that are generally present in the utility voltages. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.

DC-DC power converters are characterized by cyclic switching of circuit configurations, which gives rise to a variety of nonlinear behaviors. Their occurrence in DC-DC power converters makes the system analysis, control and behavior prediction difficult. An enhanced modeling method allowing obtaining an accurate description of the converter behavior is presented in this paper. The principal of ramp compensation is introduced and dynamical compensation ramp is proposed to both suppress converter nonlinear phenomena and ensure the peak current regulation for a wide range of reference variation.

DC-DC power converters are characterized by cyclic switching of circuit configurations, which gives rise to a variety of nonlinear behaviors. Their occurrence in DC-DC power converters makes the system analysis, control and behavior prediction difficult. An enhanced modeling method allowing obtaining an accurate description of the converter behavior is presented in this paper. The principal of ramp compensation is introduced and dynamical compensation ramp is proposed to both suppress converter nonlinear phenomena and ensure the peak current regulation for a wide range of reference variation.

DC-DC converters are nonlinear systems that exhibit a complicated nonlinear phenomena, its modelling presents the basic step of its analysis and control. In this work, we propose a discrete modelling technique that allows an accurate description of the converter behaviour with a minimum of simplifying assumptions and validity hypothesis. The proposed method validation is achieved by means of simulation and a comparative study results.

The paper deals with the problem of switched dynamical systems modeling especially in DC-DC converters case study consideration. It presents two approaches to describe accurately the behavior of this class of systems. To clarify the paper s contribution, the proposed approaches are validated through simulations and experimental results. A comparative study, between the obtained results and those of other techniques from the literature, is given to evaluate the performances of the studied approaches.

L\u27objectif de cet article est de démontrer la possibilité de faire osciller à 1.6 µm un amplificateur à fibre double gaine dopée erbium opérant dans la bande C, en ajustant les pertes intra-cavité. Deux configurations de cavité ont été utilisées, une cavité en anneau et une cavité en forme de huit. Dans les deux cas, il est possible d\u27obtenir l\u27oscillation à 1.6 µm en continu ou bien en impulsions ultra-courtes

This paper deals with Takagi-Sugeno (T-S) systems stabilization based on dynamic output feedback compensators (DOFC). In fact, only few results consider DOFC for T-S systems and most of them propose quadratic Lyapunov functions to provide stability conditions, which may lead to conservatism. In this work, to overcome this drawback and to enhance the closed-loop transient response, we provide for T-S uncertain closed-loop systems non-quadratic stability conditions. Based on a fuzzy Lyapunov candidate function and the descriptor redundancy property, these stability conditions are written in terms of linear matrix inequalities (LMI). Afterward, the DOFC is designed with H ∞ criterion in order to minimize the influence of external disturbances. Finally, a few academic examples illustrate the efficiency of the proposed approaches.

In this paper, new robust H ∞ controller design methodologies for Takagi-Sugeno (T-S) descriptors is considered. Based on Linear Matrix Inequalities, two different approaches are proposed. The first one involves a ''classical closed-loop dynamics'' formulation and the second one a ''redundancy closed-loop dynamics'' approach. The provided conditions are obtained through a fuzzy Lyapunov function candidate and a non-PDC control law. Both the classical and redundancy approaches are compared. It is shown that the latter leads to less conservative stability conditions. The efficiency of the proposed robust control approaches for T-S descriptors as well as the benefit of the redundancy approach are shown through an academic example. Then, to show the applicability of the proposed approaches, the benchmark stabilization of an inverted pendulum on a cart is considered.

This paper deals with Takagi-Sugeno (T-S) systems stabilization based on a static output feedback (SOF) non-PDC control law. To investigate SOF stabilization, the closed loop dynamics is written using a descriptor redundancy formulation. This approach allows avoiding appearance of crossing terms between the controller's and the T-S system's matrices. Thus, based on a fuzzy Lyapunov candidate function (FLF), a LMI based design methodology is provided. Then, a H-infinity criterion is considered to attenuate external disturbances. Finally, an academic example illustrates the efficiency of the proposed approach.

Stabilization issue for discrete-time interconnected switched system is studied in this paper. A global large scale discrete-time system can be decomposed into a set of small interconnected switched subsystems. Thus, a decentralized switched state feedback controller is considered to stabilize the global large scale switched system. The stability conditions, obtained from a candidate multiple switched Lyapunov function, are proposed in term of Linear Matrix Inequality (LMI). A numerical example is given to illustrate the effectiveness of the proposed approach.

Dans cet article, on s'intéresse à la synthèse de lois de commande décentralisées pour les systèmes de grande dimension représentées par un ensemble de descripteurs de type Takagi-Sugeno interconnectés. Basées sur une fonction candidate floue de Lyapunov, des conditions suffisantes garantissant la stabilité en boucle fermée de l'ensemble à commander sont écrites sous la forme d'Inégalités Linéaires Matricielles. Un exemple numérique est proposé pour illustrer l'efficacité de l'approche proposée.

This work concerns the tracking problem of uncertain Takagi-Sugeno (T-S) continuous fuzzy model with external disturbances. The objective is to get a model reference based output feedback tracking control law. The control scheme is based on a PDC structure, a fuzzy observer and a H 1 performance to attenuate the external disturbances. The stability of the whole closed-loop model is investigated using the well-known quadratic Lyapunov function. The key point of the proposed approaches is to achieve conditions under a LMI (linear matrix inequalities) formulation in the case of an uncertain and disturbed T-S fuzzy model. This formulation facilitates obtaining solutions through interior point optimization methods for some nonlinear output tracking control problems. Finally, a simulation is provided on the well-known inverted pendulum testbed to show the efficiency of the proposed approach. and is interesting when the premise variables are measured . The second one involves dynamic state feedback .