New State Observer Based On Takai-Sugeno Fuzzy Controller of Induction Motor

International audienceThis paper presents a nonlinear observer-based on Takagi-Sugeno (T-S)fuzzy controller design approach for induction motor (IM). The peculiarity of this paper is the synthesis of a mono-Luenberger observer for highly coupled system. The TS fuzzy model is firstly used to approximate the nonlinear IM systems. Next, based on the differential mean value theorem combined to the sector nonlinearity transformation , a nonlinear fuzzy observer is designed to estimate the system states in order to implement the fuzzy controller. Then, the parallel distributed compensator (PDC) scheme is used to design the fuzzy controller for the overall system. Fuzzy Controller and observer gains are obtained by solving a set of Linear Matrix Inequality (LMI).Finally, illustrative simulation results represented to validate the performance of the proposed approach

Robust control strategies for hybrid solid oxide fuel cell systems

Solid Oxide Fuel Cell (SOFC) systems are electrochemical energy conversion devices characterized by the use of solid oxide as the electrolyte. They operate at high temperatures (between 800± ¡ 1000±C). Mitigating fuel starvation and improving load-following capability of SOFCs are conflicting control objectives. In this thesis, this issue is addressed using a hybrid SOFC ultra-capacitor configuration. The fuel cell is controlled by incorporating a steady-state property of fuel utilization into an input-shaping framework. Two comprehensive control strategies are developed. The first is a Lyapunov-based nonlinear control and the second is a standard H-infinity robust control. Both strategies additionally control the state of charge (SOC) of the ultra-capacitor that provides transient power compensation. A hardware-in-the-loop test-stand is developed where the proposed control strategies are verified. An investigation to improve the hybrid fuel cell system by incorporating a lithium-ion battery as an additional power source is conducted. Combining both battery and ultra-capacitor with a fuel cell is potentially a winning combination especially for high power applications. A novel SOC estimation method for lithium-ion battery is investigated. Based on the combined ultra-capacitor battery hybrid system, a lyapunov-Based nonlinear control strategy is designed

Electrical Characteristics Analysis of High-Efficiency SnS Solar Cells

The simulation of SnS homojunction solar cells involved systematically adjusting key parameters, such as doping concentration and layer thickness, to optimize their photovoltaic performance. The study identified that optimal efficiency is achieved with a carrier concentration of 5.5 × 1015 cm⁻³ in the front n-type region, a 500 nm thick n-layer, and a 500 nm thick p+ layer with a carrier concentration of 3 × 10¹⁶ cm⁻³. Under these conditions, the solar cell demonstrated excellent electrical characteristics, including an open-circuit voltage (Voc) of 0.90 V, a short-circuit current density (Jsc) of 34.20 mA/cm², a fill factor (FF) of 0.829, and an efficiency (η) of 25.71%. These results underscore the importance of precise control over material properties and structural dimensions in achieving high-efficiency SnS-based solar cells, positioning SnS as a promising material for future photovoltaic applications

Communicating Diversity Online

Subject to demographic changes and strong internationalization, more and more multinational corporations claim to have diversity management policies and are offering diversity sections within their corporate websites. This thesis critically analyses the online content of 25 multinational corporations considered as the best workplaces in 2012. By analysing their online communication strategy on diversity, the purpose is to understand how they define diversity and in which ways they communicate about it. Findings show that only one corporation actually defines diversity but that several dimensions of diversity are covered within the online content of the multinational corporations. Some companies appear to communicate more or equally on less-­‐-­‐-­‐visible differences, which seems to show a deeper understanding of diversity, while some others strongly rely on the social justice case. By analysing and comparing those contents on diversity, the study reveals how defining and communicating ‘diversity’ is complex as the quality and attention given to it varies among the companies. It also shows that mind-­‐-­‐-­‐set influences the way diversity is approached. Overall, this study extends and builds on existing scholarship in diversity management in general and corporate communication in particular

Des nouvelles approches de commande et d’estimation non linéaires robustes dédiées aux entraînements électriques

The purpose of the research presented in this thesis is to propose a methodology for the control and observation of the induction motor (IM) based on the algorithms using the mean value theorem (MVT) and the transformation by sector non-linearity approach. In the first step, the different control techniques of electric drives were identified and analyzed. A robust state and estimation feedback control approach is then developed with variable parameters. In the field of low power, the removal of the mechanical speed sensor can be of economic interest and improve operational safety. We have presented two categories of methods that allow reconstructing and controlling the rotor speed with desired quantities under field-oriented control of the IM’s machine, the MVT observer and the robust MVT controller respectively. All the solutions have been validated by numerical simulation and affirmed by experimental tests to compare the accuracy and dynamics characteristics of the different methods with the MVT control. Finally, new robust control and estimation approaches with a novel representation for uncertain systems with varying parameters based on the MVT and sector nonlinear addressed to control the IM ‘s machine with FOC control. The results of the various simulation tests and the different experimental trials put into evidence the robustness and the success properties of the proposed algorithms. The thesis ends with a review of our contribution in terms of research

Commande et synthèse des observateurs non linéaires dédiés aux entraînements électriques avec défauts

Les travaux de recherche présentés dans cette thèse, a pour but de proposer une méthodologie de commande et d’observation de la machine synchrone MSAP basée sur les algorithmes à base de la valeur moyenne (MVT) et les transformations par secteurs non linéaires. Dans une première étape, les différentes techniques de commande des entraînements électriques ont été recensées et analysées. Une approche de commande PDC est ensuite élaborée. Dans le domaine des faibles puissances, la suppression du capteur mécanique de vitesse peut présenter un intérêt économique et améliorer la sûreté de fonctionnement. Nous avons présenté deux catégories de méthodes qui permettent de reconstituer et contrôler cette grandeur de vitesse rotorique, l’observateur et le régulateur par l’approche MVT robuste respectivement. L’ensemble des solutions a été validé par simulation numérique pour comparer les caractéristiques de précision et de dynamique des différentes méthodes avec la commande MVT. Finalement, des nouvelles approches de localisation et de détection du défaut ont été traitées une fois le modèle défaillant de la MSAP est établi. Les résultats des différents tests de simulation ont mis en preuve les propriétés de robustesse des algorithmes proposés. La thèse se termine par un bilan de notre contribution en termes de recherche

La production forestière : une alternative à l'urbanisation en forêt ? Eléments de réflexion à partir du cas du massif d'Uchaux (Vaucluse)

Décrit une étude de l'I.A.R.E. sur les points suivants : -constat sur l'extension actuelle du mitage, - analyse de la dynamique du phénomène, - étude de cas, - analyse des enjeux. Evoque les possibilités de débouchés commerciaux