Magnetoelastic modelling in soft nanocrystalline alloys

Magnetoelastic effects in ultra soft nanocrystalline alloys are investigated theoretically and experimentally. From Hc measurements, extraction of magnetoelastic contribution is carried out using a formalism obtained revisiting random anisotropy model (RAM) in the light of domain walls (DW) displacements, our approach based on theoretical investigations on the way of a reversal of a correlated volume (CV) located in the vicinity of a DW. Modelling of magnetoelastic effects shows that even in perfectly relaxed samples, a magnetoelastic contribution exists due to elastic frustration experienced by a CV during its magnetization reversal. Magnitude of this energy is large enough to drive coercivity of samples featuring grain diameter D around 10 nm, which are of major interest for applications

Matériaux magnétiques et solutions innovantes de filtrage CEM pour applications aéronautiques

L'industrie aéronautique, dans le cadre de l'avion plus électrique, met en oeuvre le remplacement d'actionneurs pneumatiques ou hydrauliques par des actionneurs électromécaniques. Cela permet de réduire le nombre de réseaux de distribution présents dans l'avion, de faciliter la maintenance et d'améliorer le rendement. Le but final est de réduire la masse et d'améliorer l'efficacité énergétique globale d'un avion pour réduire sa consommation en carburant. Les travaux de ce mémoire de thèse s'inscrivent donc la logique de réduction de la masse des convertisseurs tout en assurant des critères de perturbations CEM (Compatibilité ElectroMagnétique). En effet, les normes CEM sont de plus en plus contraignantes, en particulier les domaines sensibles tel que l'aéronautique. Les filtres CEM sont donc de plus en plus nombreux. Dans ces filtres, les composants magnétiques occupent plus de 50 % de la place et surtout de la masse. L'objectif de cette thèse est de faire émerger des solutions innovantes, en dotant les filtres CEM passifs d'un composant magnétique unique pour les perturbations de mode conduites afin de réduire sa masse. Afin de comprendre leur fonctionnement, suite à une étude bibliographique, nous avons réalisé une étude comparative de topologies à composant magnétique unique. Nous avons développé un outil de modélisation fréquentielle du composant magnétique unique. A partir d'une modélisation > nous avons pu prendre en compte l'environnement du composant magnétique (Réseau Stabilisateur d'Impédance de Ligne (RSIL), Source de perturbations, Capacités) et une modélisation plus fine des propriétés magnétiques du composant. Grâce à un modèle gyrateur-capacité, nous avons pu prédire les performances du filtre complet dans son environnement et l'optimiser. Cette étude nous a permis de réaliser une topologie de composant magnétique unique plus compacte et plus performante que la topologie existante. Par ailleurs, nous avons démontré la faisabilité de l'intégration sur PCB (Printed Board Circuit) d'alliage nanocristallin en réalisant une autre topologie de composant unique basée sur les mêmes facteurs que la précédente mais intégrée dans un PCB. Les verrous technologiques auxquels nous avons été confrontés et les solutions que nous avons proposées pour les résoudre sont détaillés dans le mémoire.In the context of the more electric aircraft, the industry replaces pneumatic or/and hydraulic actuators for electromechanicalactuators. The ultimate goal is to reduce the weight and improve the overall energy efficiency of an aircraft to reduce fuelconsumption. This thesis aims the mass reduction converters while providing criteria EMC interference (electromagneticcompatibility). In fact, EMC standards are becoming more stringent, particularly in sensitive areas such as aeronautics. EMCfilters are more numerous. In these filters, the magnetic components have more than 50% of the space and weigth. Theobjective of this thesis is to design innovative EMC filters solutions, using a single magnetic component, to reduce conducted disturbances (common and differential modes). Following a review of the literature, we conducted a comparative study of single magnetic component topologies. We have developed a modeling tool frequency magnetic single component. From a modeling > we have to take into account the environment of the magnetic component (Impedance Stabilization Network Line (LISN), Source disturbances and capacities) and a finer modeling of magnetic properties of component. With a gyrator-capacitor model, we could predict the performance of the complete filter in its environment and optimize it. This study has allowed us to achieve a unique magnetic topology component more compact and efficient than the existing topology. In addition, we have demonstrated the feasibility of integrating PCB (Printed Circuit Board) of nanocrystalline alloy by performing another single component topology based on the same factors as above but integrated into a PCB. The technological obstacles which we faced and solutions we have proposed to solve them are detailed in the report.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Caractérisations physicochimique et magnétique de rubans nanocristallins à haute perméabilité et étude de leur intégration en électronique de puissance

Nanocrystalline alloys are recent magnetic materials and the behavioural laws described and used for the elaboration process are not established for industrially high performances alloys. After a short talk on nanocrystalline specificity, and on the basis of industrial account about their performance decreases due to packaging constraints, we focused on the analysis and comprehension of magnetization mechanism. The magnetoelastic effects are pointed out and the discrimination of the various sources of anisotropy are then put forward. The outcome of manufacturing process and the high dynamic performances of nanocrystalline alloys suggest them as first-rate materials in power electronics applications. The magnetic high frequency characterizations of these materials are of great interest for power designer to optimize magnetic components size/cost, as well as for manufacturers to provide a feedback to elaboration process (compositions and heat treatments). In this context, we propose here to develop a high frequency characterization of FeCuNbSiB, assuming losses prediction and hysteresis loop calculation based on a Loss Surface model (LS) and an optimization procedure to evaluate global performances of the materials in power electronics design framework.Les alliages magnétiques nanocristallisés (FeCuNbSiB) sont depuis quelques années présents sur le marché de l'électronique de puissance. Cependant, les lois comportementales décrites et profitables en vue de l'optimisation de ces alliages ne sont pas établis pour les nuances les plus performantes industriellement. Dans un premier volet, cette étude s'oriente alors vers l'analyse et la compréhension des mécanismes d'aimantation. L'importance des effets magnétoélastiques et la discrimination des différentes sources d'anisotropie sont alors mises en exergue. Dans un second volet, l'intégration des alliages nanocristallins dans les applications d'électronique de puissance est investiguée par le biais de dimensionnements optimisés de composants. L'étude des performances dynamiques de ces alliages dans le cas de sollicitations électromagnétiques générées par les alimentations à découpage est alors présentée et s'appuie sur le développement d'un modèle d'hystérésis scalaire dynamique LS (Loss Surface). Le dernier point fédère tous les points précédents et concerne le dimensionnement optimisé de transformateurs nanocristallins hautes fréquences. Dans le cadre d'une démarche d'optimisation, des modèles analytiques de pertes magnétiques, Joule et un modèle thermique sont alors développés. Dans ce contexte, le dimensionnement optimisé d'un transformateur en rubans nanocristallins est alors considéré pour valider in fine la démarche globale

Common Mode Choke Charactérisation method and modelling for EMI filter in Power Electronics

International audienceAn equivalent circuit has been developed to model the linear electrical behaviour of any two windings common mode chokes. Its topology is independent of size and technology and a general method of characterization, exclusively based on external impedance measurements has been presented

Common Mode Choke Charactérisation method and modelling for EMI filter in Power Electronics

International audienceAn equivalent circuit has been developed to model the linear electrical behaviour of any two windings common mode chokes. Its topology is independent of size and technology and a general method of characterization, exclusively based on external impedance measurements has been presented

What’s after Dowell – Novel Magnetic Field Resolution appliedto Analysis of Windings in Electromagnetic Devices

International audienceNovel approach to accurately compute magneto-harmonic effects in different conductorgeometries applied to coils of electromagnetic devices is presented in the paper. Largely used modelingsuch as Dowell’s or complex permeability approaches show important weakness to reflect 2Dphenomena, such as edge effect, air-gap field consideration or modeling partially fulfilled layers ofconductors. This new fully analytical modeling offers all the possibility of time consuming FEMsimulation and eliminate rising errors of any mesh based method in high frequency range as well as athigh dimensional ratios of modeled objects. The way to apply Maxwell equations is mathematicallyexplained to resolve 2D distribution of magnetic potential and field, current density and resulting losses.Unrivaled findings compared to Dowell limitations and FEAnalysis results are clearly shown

Optimization of Windings in PFC Boosts and PWM Inverters to Maximize Converter Efficiency

International audienceAn optimize design process of inductors and transformers used in switching power converters is presented in this paper. An analytical modeling of conductor physical behavior was developed to match optimization requirements, and used to compare various components with different cores - coils geometries and wire technologies. Rigorous analytical modeling was applied to achieve minimization of the losses, using homogenization of the stack of wires in equivalent conductive layers of the coils, first introduced by Dowell and improved here. The resolution has been carried out for many different shapes of conductors. All the results are compared to FEM simulations ones and both are analyzed to compare in a quantitative way proximity and skin-depth effects. Then, taking into account the harmonic content of current waveforms, conductor's losses are minimized. It is highlighted that losses could largely be reduced by improvements of coil structure and the choice of conductor's shapes. The benefit of using an optimized design procedure to select best industrial solution has been proven

Complex Permeability Measurements in a Nanocrystalline Toroidal Core

In the design of power electronic converters, the choice of the suitable magnetic alloys and the measurement of the variations of their magnetic properties versus the temperature are fundamental issues. A theoretical model based on Neel theory that takes into account wall displacement and coherent rotation is elaborated to derive the expression of the complex permeability versus the frequency. The static and the dynamic behaviour has been considered in this model. The dependence of temperature is implicit in this model, i.e. the parameters involved in the expression of the complex permeability may depend on the temperature. An impedance analyser has been used to measure the open circuit and short circuit complex impedances of a toroidal core versus the frequency at several temperatures ranging from 20°C to 180°C. The complex permeability of the material is then deduced. Finally, the theoretical model is used to identify the domain susceptibility and the anisotropy energy of the materials. The effect of temperature on these parameters is analyzed. The results obtained are valuable for the design of power electronic converters from the magnetic and thermal viewpoints, which prove the need for the combination of heat transfer and magnetic mechanisms at the design

Modélisation des effets magnétoélastiques dans les matériaux nanocristallins ultradoux

Conférence Matériaux 2006 Dijo