WorldCat Identities

Lebey, Thierry

Overview
Works: 27 works in 46 publications in 2 languages and 48 library holdings
Roles: Thesis advisor, Other, Author
Publication Timeline
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Most widely held works by Thierry Lebey
Off-line and on-line partial discharges detection in low voltage motors of electric vehicle fed by a PWM inverter using non-intrusive sensor by Thibaut Billard( Book )

3 editions published between 2014 and 2015 in English and held by 3 WorldCat member libraries worldwide

To control the speed of the motor in an electric vehicle, one solution is to use in the powertrain an inverter drive with pulse width modulation (PWM). This device is recreating a sinusoidal current on each phase with a high number of short pulses of the same amplitude but with a dynamic duty cycle. Recent advances in power electronics allowed switching time to be quicker and quicker thus creating voltage pulses with shorter and shorter rise time. The use of PWM inverter to fed low voltage is now widespread but not without posing well-known problems regarding the reliability of the machine. When an electric motor is fed with a very number of pulses per second, each pulse is not propagating immediately along the winding and thus the voltage distribution is not uniform as in the sinusoidal case. As a result, most of the voltage is located within the first turns of the coil during the first moment of the switching. When the motor is random wound, first and last turns of the same coil could be adjacent thus putting high demand on the turn-to-turn insulation. Impedance mismatch between power cables and motors terminals could lead to overvoltage which are increasing the electrical stress on the insulation system. In the worst-case scenario, partial discharges could occur and contribute to the gradual deterioration of the insulation materials thus leading to premature failure. If partial discharges are easily detected with sinusoidal voltage with standard testing procedure, it becomes much harder to so when the sample under test is fed by a PWM inverter drive. Indeed, it is very difficult to spot very low amplitude partial discharges signals among very large amplitude voltage and current. Moreover, the PWM inverter is generating electro-magnetical noise, which is highly disturbing in partial discharge detection using RF non-intrusive sensor. Worse still, some electric motors having passed successfully AC or repetitive impulses acceptance tests may still fail prematurely when fed by a PWM inverter drive. The aim of this Ph.D thesis is thus to develop a non-intrusive partial discharges detection method, using a non-intrusive sensor, off-line and on-line in an electric motor fed by a PWM inverter drive. To achieve this, a series of experiments, gradually growing in complexity, will test the detection method with harsher and harsher conditions, thus closer and closer to realistic electric vehicle operating conditions. From a single-phase test on an electric stator to a full-scale test on an industrial engine test bench, off-line and on-line detection proves to be possible. In addition, visual observations and experiments have been carried out to better understand the physics of the observed light emitting discharges
Contribution à l'intégration 3D de composants passifs pour l'électronique de puissance by Thi Bang Doan( Book )

3 editions published between 2014 and 2015 in English and held by 3 WorldCat member libraries worldwide

The performance of power electronics systems has been driven by relentless progress in semiconductor component integration over the past many years. Assemblies of active power switches and their drive circuits in compact modules enable miniaturization of the power switching part of the converters. However, the number of interconnections and discrete passive electromagnetic components such inductors, capacitors, and transformers, still limit the performance and possibilities for three-dimensional (3D) integration. An evolutionary new trend will require substantial reduction in the structural passives associated with active devices and system-level packaging to support increased demands for miniaturization, high performance, high reliability, and cost-effectiveness for power electronics. The designs of 3-Dimensional Integrated Passive and Active Component (3D IPAC) modules are being developed thanks to advances in integrated technology and high dielectric permittivity materials, which are the focus of this dissertation. This work is performed mainly on capacitors because they are widely-used passive components, found in almost all electronic circuits with high volume and large footprint. High permittivity ferroelectric material is selected for compatibility with a simple and economical screen-printing technology aimed at fabricating planar integrated capacitors for different application purposes. Semiconductor dies and their drivers, placed directly on the surface of multilayer capacitive substrates, make it possible to reduce the size and interconnection lengths between active and passive devices, thus increasing reliability as well as performance of power electronic modules. The decoupling and flying functions of planar multilayer integrated capacitors are verified through experimentation thanks to two proposed DC-DC converter topologies. Further study is also carried out to observe the effects of the cold isostatic pressing (CIP) process on dielectric properties of ferroelectric thick films. Under high pressure on multiple directions, the dielectric layer thickness is reduced, resulting in a higher capacitance value. Comparisons between compressed and uncompressed capacitors with the same configuration show that CIP is an effective way to increase capacitance value. This benefit suggests the opportunity for a design trend using a high capacitance value for greater filtering efficiency and decoupling purposes
Etude du procédé de fabrication de noyaux ferrimagnétiques complexes par mise en forme isostatique : application aux transformateurs intercellulaires by Trong Trung Le( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

Les besoins actuels en électronique de puissance concernent principalement la fiabilité et l'augmentation de la densité de puissance. Dans les deux cas, ce qu'il est convenu d'appeler l'intégration de puissance constitue une solution. Les problèmes de fiabilité peuvent être résolus par la diminution du nombre d'interconnexions et par la maitrise complète de la réalisation des convertisseurs et, ceux liés à la densité de puissance, par la réduction des dimensions et par la mutualisation d'un certain nombre de fonctions: intégration des passifs, substrats fonctionnalisés, composants de couplage... Ceci passe nécessairement par une stratégie de choix de structures de conversion permettant de répondre à ces questions. Les convertisseurs multi-niveaux, multicellulaires entrelacés sont un exemple de structure permettant de réduire la taille et le volume des composants magnétiques. Le point clé de ces structures réside dans le partage des flux magnétiques entre les différentes phases du convertisseur via un transformateur intercellulaire (ICT). Ce type de composant permet l'entrelacement de nombreuses cellules de commutation. Il consiste en un noyau magnétique de forme spécifique et souvent complexe. Les travaux réalisés dans le cadre de cette thèse concernent le développement de technologies permettant la réalisation de composants magnétiques de type ICT en vue de leur intégration. Les principales propriétés du matériau (magnétiques et diélectriques) nécessaires à la réalisation de ce type de composant nous ont conduits à choisir une ferrite de type Ni0,30Zn0,57Cu0,15Fe2O4 susceptible de s'adapter tant aux fréquences de fonctionnement qu'à la gamme de puissance envisagée. Différents procédés de mise en œuvre (et les paramètres qui leur sont associés) ont été étudiés. Il s'agit soit du formage, via l'utilisation de moules souples ou encore du pressage isostatique, et de l'usinage soit à cru soit après frittage. Concernant l'usinage, deux systèmes distincts nous ont permis la mise en forme des noyaux complexes soit en 2 D soit en 3D. Les résultats de cette démarche tant en termes d'objet que de propriétés du composant, sont présentés. L'influence des différents paramètres utilisés lors de la réalisation (température de frittage, pression,...) sur les caractéristiques finales est aussi étudiée
PHENOMENES PREDISRUPTIFS DANS LES ISOLANTS SOLIDES : CAS DU POLYETHYLENE ET DU POLYEPOXY by Thierry Lebey( Book )

2 editions published in 1989 in French and held by 2 WorldCat member libraries worldwide

COMPREHENSION DES PHENOMENES PHYSIQUES SUSCEPTIBLES DE CONDUIRE UN MATERIAU A LA RUPTURE DIELECTRIQUE SOUS L'ACTION CUMULEE D'UN CHAMP ELECTRIQUE MODERE ET DU TEMPS
Nouveaux matériaux composites à gradient de permittivité structurés par un champ électrique et leur application pour la gradation de potentiel by Louis Lévêque( Book )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

New developments in power electronics allow increasing the power density of the conversion systems. This means that the insulating materials, such as the encapsulation in power modules, are more are more stressed. If the electric field reinforcements in insulating polymers reach critical values, this can lead to a partial discharge activity, electrical treeing and eventually a complete breakdown of the insulation. The objective of this thesis is to study the appropriate matching of the dielectric properties of insulating polymer composites in order to reduce the electrical stress in the regions of field reinforcement. A new approach to minimize the reinforcements is proposed through a local structuration of the composite material allowing an auto-adaptive permittivity gradient where the largest stresses are present. This structuration is achieved thanks to the application of a DC electric field during the elaboration process of the composite material, leading to the displacement of the particles by electrophoresis. The field grading material is an epoxy matrix filled with high permittivity particles (strontium titanate SrTiO3 or barium titanate BaTiO3). Applying a DC electric field on the liquid resin containing the particles induces their accumulation on the high voltage electrode, building an accumulated layer highly concentrated in particles, conferring to this region a higher permittivity. Each region of the structured composite (accumulated layer and low concentrated region) was characterized in terms of dielectric properties (permittivity and losses). While the low concentrated region of particles keeps a permittivity close to that of homogeneous composites one, the accumulated layer exhibits a significant increase due to the increase in the local particle content. The particle concentration in each region of the structured material were precisely determined, and the related permittivity values are in good agreement with the permittivity values of the homogeneous composite materials of the same filler content. This shows that the accumulated layer was not organized in a particular way. Regarding the dielectric strength of the accumulated layer, its values are large enough for the applications and these values follow the typical power law versus thickness. Finite element methods prove that these materials are appropriate for minimizing the electric field reinforcements at the triple point, between the metal, the ceramic and the encapsulation. These results highlight the interests of these new kind of field grading materials. They could allow improving the reliability and the robustness of power modules or other electrical systems working at high field
Contribution à l'étude de solutions non destructives pour la détection et la localisation de défauts électriques dans les structures électroniques 3D by Nicolas Courjault( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

L'objectif de la thèse fut d'étudier plusieurs techniques d'analyse de défaillance (Microscopie magnétique, Thermographie à détection synchrone, Tomographie à Rayons X, Réflectométrie Temporelle) sur leur propriété de localisation de défaut électrique (Court-circuit, circuit ouvert, ouvert résistif, etc.) sur des systèmes et composants électroniques 3D. Des possibilités d'évolution de ces techniques sont suggérées afin de permettre d'assurer la localisation des défauts dans ces nouveaux composants électroniques. Ceci passe notamment par la mise en place d'analyses magnétiques sur des échantillons inclinés ainsi que par l'introduction d'une imagerie de phase, et d'amplitude magnétique. Ce travail a également permis de proposer le couplage d'informations obtenues par microscopie magnétique et tomographique à rayons X dont l'ensemble serait piloté par simulation magnétique 3D
Détermination et impact de l'existence de décharges partielles dans une chaîne de traction ferroviaire utilisant des composants à base de SiC by Robin Acheen( Book )

2 editions published in 2020 in English and held by 2 WorldCat member libraries worldwide

The introduction of SiC-based components in the electromechanical chain presents numerous advantages, but has consequences on the reliability of the insulation systems in the machine. For switching frequencies up to 5 kHz, and dV/dt varying from 15 to 30 kV/µs, a system lifetime of around 40 years (or 200 000 hours) must be guaranteed. The question that arises is to know what margin insulation systems of the current equipment have. It is thus necessary to determine whether, under normal operating conditions, phenomena that did not previously exist or were not completely apprehended will appear with the transition to SiC-based inverters. One of these phenomena is Partial Discharge (PD) and its development in machines, and more precisely in the turn-to-turn, turn-to-ground, and phase-to-phase insulation systems. Therefore, the objective of the thesis is to study the influence of the electrical stress imposed by SiC-based components on the insulation of machines. To do so, a first phase of electrical stress identification allows accounting for the constraints undergone by the machine. In a second phase, these constraints are reproduced on representative samples, which are thus subject to accelerated aging, in order to establish aging laws and to study the degradation of the insulation systems under stress
On-line non-intrusive partial discharges detection in aeronautical systems by Cédric Abadie( Book )

2 editions published in 2017 in English and held by 2 WorldCat member libraries worldwide

L'évolution de l'électronique de puissance ces dernières années a entraîné une augmentation de la densité de puissance et une diminution du coût des onduleurs de tension à modulation de largeur d'impulsion (MLI). Ces évolutions ont répandu l'utilisation de convertisseurs de puissance pour les applications de variateurs de vitesse ce qui a permis le développement du concept d' " avion plus électrique ". Ce concept consiste à remplacer un des vecteurs énergétiques (pneumatique ou hydraulique) par l'énergie électrique. Cependant, le développement du réseau électrique a entraîné une augmentation de la tension embarquée, ce qui a conduit à un vieillissement prématuré des équipements électriques embarqués. La forme de tension appliquée, appelée "modulation de largeur d'impulsion" (MLI), est constituée de trains d'impulsions. Avec l'application de ces impulsions, la tension n'est plus distribuée de manière homogène le long du bobinage. Dans ce cas, on pourra observer d'importantes différences de potentiel entre les spires d'une même phase voire entre deux phases du bobinage. En outre, un autre paramètre important provient du type d'enroulement des moteurs utilisés par l'industrie. L'enroulement aléatoire est la technique de bobinage la plus courante pour les moteurs basses tensions car cette méthode présente un faible coût. Le risque induit par ce type d'enroulement est que la première et une des dernières spires de la première bobine peuvent être proches l'une de l'autre. Dans ce cas, jusqu'à 80% de la tension sera supportée par quelques dizaines de microns d'émail, et les systèmes d'isolation existants ne sont pas dimensionnés pour résister à de telles contraintes. L'utilisation de longs câbles reliant l'onduleur au moteur peut aussi provoquer des surtensions importantes aux bornes du moteur. Ce phénomène s'explique par le fait que le câble se comporte comme une ligne de transmission qui n'est pas adaptée en termes d'impédance au bobinage du moteur. De plus, ces importantes différences de potentiel associées à de faibles pressions, présentes dans les zones dépressurisées de l'aéronef, peuvent entraîner l'apparition de décharges partielles. Les décharges partielles sont des décharges électriques qui court-circuitent partiellement l'intervalle entre deux conducteurs. Il existe de nombreuses méthodes de détection bien connues pour les tensions AC et DC, cependant, la détection sous tension de type MLI dans des moteurs basse tension est beaucoup plus complexe. Les signaux de décharge partielle sont en effet intégrés dans le bruit électromagnétique généré par la commutation. Le but de cette thèse est donc de développer un procédé de détection et un procédé de filtrage permettant une détection non intrusive et en fonctionnement (on-line) des décharges partielles dans le domaine aéronautique afin de qualifier les systèmes d'isolation électrique utilisés dans les aéronefs
Contribution à l'étude de la gradation de potentiel dans les modules de puissance haute tension by Cyrille Duchesne( Book )

2 editions published in 2009 in French and held by 2 WorldCat member libraries worldwide

L'augmentation des densités de puissance dans le domaine de la traction ferroviaire conduit aujourd'hui au développement de convertisseurs intégrés. Cette intégration n'est toutefois possible que si l'on sait dimensionner au plus juste l'ensemble des éléments qui constitue ces convertisseurs. Du point de vue de l'isolation électrique, il est donc nécessaire d'avoir une caractérisation la plus large possible de l'ensemble des matériaux isolants utilisés dans le packaging des composants de puissance ainsi qu'une bonne compréhension de leurs mécanismes de défaillances. Ces points s'avèrent d'autant plus critiques que la réduction des dimensions d'une part et l'augmentation des calibres en tension des composants d'autre part se traduisent par des contraintes de plus en plus sévères. Répartir la contrainte électrique de façon homogène est donc d'un intérêt majeur lorsqu'il s'agit de maintenir l'intégrité de ces systèmes. Le travail présenté ici consiste en une étude approfondie des problématiques liées à la gradation et en la présentation de deux solutions de gradation du potentiel, l'une utilisant des matériaux hybrides et l'autre des lignes conductrices à potentiel flottant. Différents outils théoriques et pratiques ont été développés et utilisés. Un code de calcul par éléments finis (CEF) est utilisé afin de prédire la répartition de la contrainte (potentiel et champ électrique) dans une structure de test prédéfinie. L'influence de la réfraction des équipotentielles aux interfaces de différents diélectriques est ensuite étudiée. L'utilisation d'un matériau présentant une variation non - linéaire de sa caractéristique courant tension sur la répartition homogène du champ électrique est discutée et nous montrons qu'un tel comportement n'est pas une condition nécessaire pour obtenir une réduction satisfaisante du champ électrique. Différentes méthodes permettant de caractériser ce type de matériau à travers des mesures directes de la contrainte électrique par sonde à champ nulle et indirecte par des mesures de décharges partielles sont ainsi proposées. Enfin, la gradation du potentiel en utilisant des lignes métalliques inspirées des techniques de répartition par anneaux de garde ou plaque de champ est envisagée. Une optimisation de la structure d'étude par calcul CEF est d'abord réalisée, puis la caractérisation diélectrique à travers des mesures de décharges partielles et de rupture diélectrique confirme le bien fondé de cette approche
Cold isostatic pressing of screen-printed dielectric for power electronics passive component integration by Thi Bang Doan( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Système d'encapsulation multicouche pour la gradation de potentiel dans les modules de puissance : apport des matériaux nanocomposites à conductivité contrôlée by Cyril Pelvillain( Book )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

Nowadays, an optimal management of the electrical energy becomes a key point in electric systems. The conversion of energy is realized by a main component: the power converter. It is used as well for low power (few Watts) as for very high power (MWatts). The elementary block of the converters, is the switching cell made up of semiconductor power devices. The trend to reduce both the volume and the weight in many applications (for example in embedded systems) and the increase of the rating voltage of the new wide band gap semiconductors will have for consequence an increase of the stresses on the electrical insulating systems of the power module . A controlled grading of these electrical constraints in the volume is highly interesting to ensure the reliability of the system. It is therefore necessary to perform a precise characterization of the insulated materials used in the packaging of the power modules, as well as to get a good understanding of their failures mechanisms. The works presented in this dissertation consists in the study of a new strategy for the field gradation in power modules. The proposed insulation is an assembly of multi-layers made up of a thick material of electrically controlled conductivity (Epoxy/Graphene nanocomposite) and of a thin insulating layer (Parylene films). Various tools were used (both theoretical and experimental) to help dimensioning of the Electrical Insulation System (EIS). The Finite Element Method (FEM) was used to simulate the equipotential and field distribution in the structure under study and to analyse on one hand, the influence of the changes in the conductivity values of the Epoxy/Graphene nanocomposite materials and, on the other hand, the impact of the parylene (PA) films thickness on the stress grading. From an experimental point of view, the PA films were characterized for different thicknesses ranging between 10 µm and 40 µm. The Epoxy/Graphene nanocomposites of controlled conductivity were manufactured and characterized (0 to 5 % wt) for various filler contents. The field grading effects were evaluated directly in different structures thanks to surface potential measurements and (indirectly) to partial discharges measurements. The proposed multilayer EIS exhibits some improvements regarding the stress grading but also some limits depending on the conductivity of the nanocomposite. Such an EIS will have to be dimensioned taking into account the rating voltage and could offer an interesting approach for the future design of the power modules
Contribution à l'étude de l'existence des décharges dans les systèmes de l'avionique by Flavien Koliatene( Book )

2 editions published in 2009 in French and held by 2 WorldCat member libraries worldwide

Thanks to the progress realized in power electronics field, the electric power embarked on the transport vehicles (automobile, railroad, maritime...) is in constant increase. This evolution is also occurring in aircrafts, leading inevitably to an increase of the voltage level. The control flexibility, the facilitated maintenance as well as the cost are the assumed assets of systems called "More Electric". However, the implementation of more electric systems can lead to the occurrence of unfavourable phenomenons to the insulation electrical systems such as discharges. It seemed therefore necessary to develop a study on initiation conditions of Partial Discharges (PD) to guarantee the reliability of insulation systems which is the whole chain of electric power. It is in this frame the work relates to and it is presented in this manuscript. A particular attention is carried out concerning the experimental characterization of the PD existence in the electric systems embarked in aircrafts. This is bound, on one hand, to the specific environment (pressure, temperature, humidity) and, on the other hand, to the increase of the voltage level. Until very recently, this phenomena was not taken into account in the specifications of the embarked electric equipments, considering the low functioning voltage level (115V AC and 28V DC). We remind first of all about the evolution and the need in electric power in the new generations of more and more electric aircraft. A state of the art on the measures of PD is then presented. The phenomenology of electric shocks in the air in particular Paschen law are explained. Finally, corrective expressions coming from the literature are presented and discussed. Then we present the bench test worked out allowing, on one hand the characterization of the electric strain of the air under controlled atmosphere (pressure, temperature and relative humidity) and on the other hand the measures of PD under avionics constraints
Contribution à l'étude du comportement des systèmes d'isolation des machines tournantes à courant alternatif fonctionnant sous très hautes températures (200-400°C) by Fabrice Aymonino( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

Ce travail de thèse porte sur la compréhension du comportement des systèmes d'isolation des machines tournantes alternatives fonctionnant sous très haute température. Le domaine d'application principal de ces machines est celui du désenfumage des tunnels et parkings souterrains lors d'incendies. Durant cette phase de fonctionnement critique, la température au sein de la machine peut atteindre près de 400°C. Sous de telles contraintes thermiques le comportement des isolants polymères constituant le système d'isolation de ces moteurs est actuellement mal connu. La première partie de ce travail a consisté à dresser un état de l'art des matériaux isolants employés actuellement dans la conception de l'isolation de telles machines. Notre attention s'est portée sur l'isolation entre les spires des bobinages. De manière à mettre en évidence d'éventuelles corrélations entre les dégradations subies par les isolants sous ces contraintes thermiques sévères et leurs propriétés électriques, des mesures physico-chimiques et des mesures diélectriques ont été réalisées. La description des dispositifs expérimentaux utilisés ainsi que des protocoles expérimentaux employés font l'objet de la deuxième partie de ce travail. Les résultats détaillés sont ensuite présentés dans la troisième partie. Nos résultats font apparaître une évolution des grandeurs diélectriques qui semble en bon accord avec les mesures permettant d'estimer l'état d'avancement des dégradations de l'isolant en fonction de la température d'essai. Le chapitre quatre est alors consacré à l'exploitation de ces résultats. L'analyse des gaz de décomposition a permis de proposer des schémas de dégradations des isolants étudiés
Packaging de composants grand gap haute température et haute tension by Laurent Roske( Book )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

In power electronics, one of the main research topics concerns high temperature operation of the components. Under such a constraint, the encapsulation and the passivation of the semiconductors devices in power module appear as physical and technological bottleneck. As a matter of fact, usual polymeric materials are unable to endure the temperature requirements set out in our study (350 °C) without significant loss of their dielectric properties. Therefore, gas insulation is considered and encouraging results have been obtained. The Discharges Inception Voltage is studied for different gases that could be used in high temperature power modules. Thanks to their dielectric properties and their low GWP, two gases have been selected: octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8), nitrogen (N2) being used as reference in this study. In a first step, the high temperature behaviors of the most widely used substrate materials (ceramics) are studied. A change of the conduction mechanism from a pure capacitive behavior (at low temperature) to a pure resistive one (at high temperature) is observed for both alumina and AlN samples. On the contrary, Si3N4 remains capacitive whatever the temperature. Such a behavior has an impact on the charges located at the surface. They disappear quickly for the two formers while they slowly decrease for the later. The field reinforcement associated to their existence and its impact on the DIV will not be the same. Whatever the gas under study, a local heating leads to a decrease in the DIV with temperature. A decrease of the distance between the two electrodes, leads to a decrease of the DIV changes vs Temperature. These results are compared to the measurements performed when the samples were uniformly heated. The use of gas in power packaging seems to be promising but it still needs a better understanding of the mechanisms involved
Nouveaux concepts pour l'intégration 3D et le refroidissement des semi-conducteurs de puissance à structure verticale by Kremena Vladimirova( )

1 edition published in 2012 in French and held by 2 WorldCat member libraries worldwide

The power electronics field is struggling for new material, technological and conceptual evolutions. These changes induce breakthrough in the conventional design and fabrication of static power converters with the aim to offer more efficient, reliable and compact solutions in an increasingly demanding techno economical context. This PhD thesis presents the results obtained by analyzing, realizing and characterizing an innovative concept based on vertical voltage terminations that opens the way towards the 3D integration of power devices. Moreover, the proposed concept authorizes the integration of a microchannel cooler directly into the drift region of the power device. Based on the realization of deep trench terminations, a technique initially developed for the microelectronics field, this PhD thesis presents an approach allowing the integration of multiple power devices in the same die, all sharing the same backside electrode. This document also focuses on the DRIM Cooler (Drift Region Integrated Microchannel Cooler) concept that allows the direct cooling of the device through multiple parallel microchannels integrated perpendicular to the plane of the device's PN junction. The analytical analysis is completed with numerous realizations, characterizations and practical implementations of the above mentioned concepts
Apport de la thermographie infrarouge à l'analyse de défaillance de composants et systèmes électroniques by Morgane Mousnier( Book )

2 editions published in 2019 in French and held by 2 WorldCat member libraries worldwide

Since 1960, the semiconductor industry has followed Moore's law, which predicted that the density of transistors would double every two years. Moore's law consists in two empirical laws describing the complexity and miniaturization of electronic components, with the aim to increase computer speed initially. This evolution led to the creation of more and more complex component, particularly with structures in 2.5D and 3D, where respectively dice are side by side or one on another, all in the same package. This increase in complexity has also led to new challenges in analyzing the of such components. Among all the various failure analysis techniques, the infrared thermography (IRT) has been in the frame of this PhD assignment. IRT is a non destructive and contactless infrared radiation measurement technique. The system used is composed of an InSb sensor that senses wavelength between 3-5µm, with a lateral spatial resolution about 3µm at best. Infrared radiation measurement is classically used for industrial purposes in non-destructive analysis and control of structure and mechanical parts, for example on composite or aluminum parts used in the aviation industry. Within the framework of the PhD, IRT is mainly used for three failure analysis modes on electronic components: Lock-in Thermography (LiT): LiT is an active thermography technique where the device under test (DUT) is electrically activated by a signal synchronized with the image captured by the IR camera. This analysis allows to obtain two information. On a one hand it gives the intensity of the power delivered by the exothermic defect. On the other hand, it provides information about the delay between the emission of the IR radiation by the defect and its perception by the IR camera. Temperature measurement: Temperature measurement requires a very precise calibration in order to convert photons flux into the temperature value. Fast phenomenon acquisition or trigger delay: Trigger delay is an active thermography technique based on time-related sampling of the signal. This technique allows increase artificially the camera sampling frequency in order to analyze fast and repeatable thermal phenomenon. The main difficulty about IR radiation is the surface emissivity, which is most of the time very heterogeneous for electronic components. A coating application has been demonstrated to be useful not only in temperature measurement but also in defect spotting, thanks to the improved localization precision. [...]
Contribution à l'étude des défaillances statoriques des machines asynchrones : mise au point et réalisation d'un test non destructif de fin de fabrication by Claudiu Neacșu( Book )

2 editions published in 2002 in French and held by 2 WorldCat member libraries worldwide

Anisotropic composite elaboration and modeling : toward materials adapted to systems by Guillaume Belijar( Book )

2 editions published in 2016 in English and held by 2 WorldCat member libraries worldwide

This study was aimed to demonstrate the possibility, based on a predictive approach, to tailor the structure of a composite from isotropic to anisotropic when applying an electric field. This composites have great potential for future applications such as embed capacitors or thermally conductive composites. A theoretical approach of the forces and mechanisms acting in the elaboration of anisotropic composites by chaining allowed identifying the key parameters. Based on this approach a model of particle chaining under electric field was established to predict the structuration dynamics. This model (effective dipole moment) allowed simulating more than 4500 particles. The parameters previously identified were then measured, and for the particle permittivity, a dielectrophoretic measurement method was developed, which was a first for ceramic particles. The elaboration of anisotropic composites was coupled to a novel on-line monitoring of a chaining marker (permittivity), allowing to obtain the structuration dynamics. To validate the predictive aspect of the model, experimental and numerical dynamics were compared showing the robustness and accuracy of the model, even if improvement is still possible at low filler content. In the last part, a proof of concept was demonstrated of the elaboration of anisotropic composites with fillers oriented normally to the direction of the electric field
On-line partial discharges detection in conversion systems used in aeronautics by Benjamin Cella( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

The more electrical airplane concept led industrial companies to focus a part of their efforts on risks linked to the use of high voltage in a severe environment (Low pressure, wide range of temperature and humidity ...). Associated risks are the existence and the growing of partial discharges ultimately leading to the breakdown of the system in which they occur. Considering this problematic, the Liebherr Elektronik GmbH group, in collaboration with the Laplace laboratory, launched the study of a method allowing partial discharges detection in converters intended to be used in aeronautical applications. The results of this work are the subject of this thesis. The first part brings the status of the current knowledge about partial discharges from their physical nature to the detection methods which are used. In the second part, three measurement phases assessing the efficiency of the studied method are introduced and their results discussed. Finally, in the third part, the conclusionsof our works and their perspectives are presented
Élaboration, caractérisation et modélisation de nouvelles varistances à base de dioxyde d'étain by Julien Pansiot( )

1 edition published in 2010 in French and held by 1 WorldCat member library worldwide

Many investigations have been conducted on semiconductive ceramics with a tin dioxide matrix, particularly in the high electric field and high current density ranges. The sintering process has been optimized, in order to obtain compounds with electrical properties compatible with the varistor application. Among the many dopants studied, two elements produced a remarkable electrical behavior. By doping SnO2 grains with Aluminium (III) allows an increase of their apparent conductivity and hence, widens the working range of tin oxide based compounds, up to the ZnO varistors ones. It appears that the silicium is located on the grain boundaries in the ceramic microstructure. This element reduces strongly the effective surface of the grain boundaries and causes an important diminution of the varistors working range. Simultaneously, the current-voltage behavior appears to be like those observed for a Zener diode, with non-linearity coefficients higher than 100 and nearly ideal variation profiles. The conduction modelling in the SnO2-SnO2 grain boundary area reflects that these ceramics present theoretically a higher potential than ZnO based ceramics, due to a wider SnO2 bandgap. A brief technico-economical comparison has been proposed in order to highlight the competitiveness between the two materials for the varistor applications
 
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