De l'apport de la modélisation des matériaux magnétiques doux aux applications du génie électrique

The work presented in this manuscript have been realized from September 2005 (at CEGELY) to June 2014 (at AMPERE)It concerns the elaboration of behavioural models of soft magnetic materials used in electrotechnical and/or power electronics applications.These models are after development used in simulation/design softwares to evaluate "virtually" the performances of the system in several conditions of level, waveforms, frequency, temperature,\dots They are also used in order to test and compare virtually several solutions with different sof magnetic materials on a same system. Several own or extracted frome the scientific litterature developments of quasi-staic, dynamics, frequential models are presented and discussed. Particularly, the adding of a supplementary magnitude, namely, the temperature in these models is a major asset for the electrical devices simulation/design tools. Some examples of uses of these models are applied on current transgformers, Hall effect current sensors, EMC filtors inductors and electromagnetic relays of differential breakers.Les travaux présentés dans ce mémoire ont été effectués de septembre 2005 (au CEGELY) à Juin 2014 (à AMPERE).Ils concernent l'élaboration de modèles comportementaux de matériaux magnétiques doux utilisés dans des applications électrotechniques ou/et électronique de puissance. Ce modèles sont ensuite utilisés dans des logiciels de conception/simulation pour évaluer "virtuellement" les performances du système dans différentes conditions d'amplitude, de formes d'ondes, de fréquence, de température\dots Ils sont également utilisés pour tester et comparer virtuellement des solutions avec des matériaux magnétique doux différents sur un même système. Différents développements propres ou tirés de la littérature de modèles dits quasi-statiques, dynamiques, fréquentiels sont abordés et discutés. En particulier l'ajout d'une variable supplémentaire, à savoir, la température dans ces modèles est un atout majeur pour les outils de simulation/conception de dispositifs électriques. Certains exemples d'utilisation de ces modèles sont appliqués sur des transformateurs de courant, capteurs de courant à effet Hall, inductances de filtre CEM et relais de disjoncteurs différentiels

Subfacturação e suprimentos: duas faces da mesma moeda? Estudo para o caso português.

O presente estudo pretende verificar, para uma amostra de empresas portuguesas, se existe uma relação positiva entre os suprimentos que estas recolhem dos seus sócios/accionistas e a manipulação dos resultados por via de subfacturação. Utiliza-se uma metodologia assente no uso de amostra de controlo e, face à impossibilidade de apreender directamente a existência de subfacturação, classificam-se as empresas como manipuladoras ou não por subfacturação com base na margem bruta relativa do volume de negócios da empresa-ano. São classificadas como manipuladoras por subfacturação as empresas que, no ano em causa, apresentem uma margem bruta inferior à mediana da respectiva indústria. Como previsto, a evidência empírica sugere a existência de uma relação positiva entre os suprimentos recebidos de sócios/accionistas e a classificação das empresas como manipuladoras, mesmo depois de controlados os efeitos das variações no activo fixo e da rentabilidade do activo na variação dos suprimentos

Temperature dependent extension of a hysteresis model

International audienceSome soft magnetic materials (like ferrites but not only) are strongly dependent of the temperature. In order to predict their behaviour in electrical devices, engineers need hysteresis models able to take into account the temperature. This paper is an attempt to take into account the temperature in an existing model of hysteresis through its parameters. Variations of some parameters are issued from Weiss’s works and others have to be fitted numerically. Simulation results are compared to measurements and discussed

Design of a Low-Capacitance Planar Transformer for a 4 kW/500 kHz DAB Converter

International audienceIncreasing electrification in transport sectors, from automotive to aerospace, highlights the need for low size and high power density components. The recent advent of planar technology theoretically allows to reduce considerably the size of the magnetic components. This article focuses on the design of a high frequency planar transformer intended to be used in a 4 kW 500 kHz DAB converter. In particular, the inter-winding capacitances are assessed, as they have a strong influence on the behaviour of the DAB, and in some extreme cases may impede operation entirely. Analytical and finite element models are used to evaluate the stray elements of the transformer (resistance of the conductors, inter-winding capacitance and leakage inductance), and the resulting circuit model is compared with experimental measurements. This work focuses on influences of design parameters on the transformer stray elements

Prédiction de signatures électriques dans un actionneur en prenant en compte les lois de matériaux

In an electromagnetic actuator, the magnetic circuit's main function is to beam the electromagnetic energy to the desired zone (the air-gap). In this magnetic circuit, some energies of different natures are transformed, stored, exchanged and dissipated. The performances of the softwares to represent the transient states and the losses depends on the way that the softwares evaluates all these kinds of energy. This imposes to the model to be able to describe , in transient state, all the history of the material magnetization.Our work is basing on developping simulation tools in which the magnetic circuit is a part of the heart of the energetic conversion. Some simplifying assumptions or/and couplings between methods a priori or in real time authorize us to study the transient states inside the magnetic circuits and to evaluate the losses.the coupling between the methods and the associated assumptions are described following the chapters. The results allow the fine analysis of the magnetic circuit function for several industry-oriented systems and the reflexion on eventual improvements to bring to these systemsDans un actionneur électromagnétique, le circuit magnétique joue le rôle indispensable de canalisateur de flux pour diriger l'énergie magnétique dans la zone souhaitée (l'entrefer). Au sein de ce circuit magnétique, des énergies de différente nature, sont transformées, stockées, échangées et dissipées. Les performances de l'outil informatique pour représenter les régimes transitoires et les pertes sont liées à la précision avec laquelle sont évaluées simultanément toutes ces formes d'énergie. Ce constat impose au modèle d'être à même de décrire, en régime dynamique, tout l'historique de l'aimantation du matériau.Notre travail a consisté à développer des outils de simulation dans lesquels le circuit magnétique est au coeur de la conversion énergétique. Des hypothèses simplificatrices ou/et des couplages de méthodes à priori ou en temps réel nous autorisent à étudier les régimes transitoires à l'intérieur de ces circuits et à en évaluer les pertes.Le couplage de méthodes de représentation ainsi que les hypothèses y attenant est décrit au fil des chapitres. Les résultats obtenus permettent l'analyse minutieuse du rôle du circuit magnétique pour plusieurs systèmes à vocation industrielle ainsi que la réflexion sur d'éventuelles améliorations à apporter à ces systèmes

Modélisation d'un capteur de courant asservi

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Numerical model of static hysteresis taking into account temperature

International audienceSome soft magnetic materials are strongly dependent of the temperature , because of their low Curie temperature. In order to predict their behaviour in electrical devices, hysteresis models able to take into account the temperature are needed. The Vector Play static hysteresis model is an interesting hysteresis model that can be modified in order to take into account the thermal behaviour. In this paper, the temperature is taken into account in this last model through its parameters. The variations of some parameters with temperature are mainly issued from numerical interpolation and specific assumptions. Simulation results are compared to measurements and discussed

Quasistatic hysteresis modeling with feed-forward neural networks: Influence of the last but one extreme values

International audienceA technique based on feed-forward neural network (FFNN) for modeling rate-independent scalar magnetic hysteresis is presented in this paper. The neural network discussed here is inspired by several papers presented in the literature. The training set is obtained by a Jiles–Atherton model, just to verify the feasibility of the method and to prevent measurements difficulties. We choose a FFNN model and in order to improve its accuracy and its ability to generalize, we make a little modification that can avoid some problems. Finally, a modification of the last model by adding the last but one extreme value as input of the FFNN is discussed

Numerical model of static hysteresis taking into account temperature

International audienceSome soft magnetic materials are strongly dependent of the temperature, because oftheir low Curie temperature. In order to predict their behavior in electrical devices,engineers need hysteresis models able to take into account the temperature. TheVector Play static hysteresis model is an interesting hysteresis model that can bemodified in order to take into account the thermal behavior (F. Sixdenier, O. MESSAL,A. HILAL, C. Martin, M.A. Raulet R. Scorretti, ”Temperature dependent extensionof a static hysteresis model”, IEEE Transactions on Magnetics, Volume:PP, Issue: 99) where variations of some parameters with temperature are issued orbuild thanks to the literature. The purely magnetic behavior showed some errors for”complex” low amplitude signals. These errors could be explained by (1) used toapproximate measured anhysteretic curves, which is known to be not so accurate.Accuracy might be improved by numerically interpolating measured anhystereticcurves at different temperatures Man(h, T). This last technique will be tested inthis paper. A qualitative and quantitative analysis of results will be made in orderto qualify the method as a valid extension of the vector play model in order to takeinto account the thermal behavior.Simulation results will be compared to experimental measurements. The testedmaterial is a N30 ferrite (Tc > 130◦ C). Characterization are made on standardtoroidal samples (Dext =40 mm, Dint =24 mm, h =16 mm) following the fluxmetricmethod with respect to the IEC 60404-4 standard

Conception et réalisation d'un dispositif de caractérisations magnétiques 2D en température

International audienceThe physics at play when a magnetic material is under a rotationnal flux density B or an alternative one cause differents behaviours to appear. The anisotropy existing (due to cristalline structure) in most electrical steels for 50 Hz applications amplifies these behaviours. Nevertheless, no study exists coupling temperature and anisotropy, despite a known influence on magnetic properties under alternating magnetization. Here, the design and implementation of a two-dimensionnal characterization setup allowing for temperature control is presented, along with some early results. MOTS-CLES-Anisotropie magnétique, Caractérisations magnétiques, Champ tournant, Etude en Température.Les phénomènes physiques mis-en-jeu dans un matériau magnétique soumis à un champ B alternatif ou rotatif diffèrent partiellement, ce qui aboutit à des comportements différents. Ces derniers sont accentués par l'anisotropie présentée par la plupart des tôles magnétiques utilisées dans les applications à 50 Hz (transformateurs/machines tournantes). Néanmoins, ces comportements n'ont pas été étudiés lorsque croisés avec l'influence de la température du matériau, qui est pourtant connue comme ayant une influence majeure sur les propriétés unidirectionelles. La mise en place d'un système de caractérisations magnétiques 2D permettant d'imposer la température de l'échantillon est ici présentée, ainsi que quelques premiers résultats