Recently planar magnetic technologies have been widely used in power electronics, due to good cooling and ease of fabrication. High frequency operation of magnetic components is a key to achieve high power density and miniaturization. However, at high frequencies, skin and proximity effect losses in the planar windings become significant, and parasitics cannot be ignored. This piece of work deals with the modeling and design of planar integrated magnetic component for power electronics applications. First, one-dimensional eddy current analysis in some simple winding strategies is discussed. Two factors are defined in order to quantify the skin and proximity effect contributions as a function of frequency. For complicated structures, 2D and 3D finite element analysis (FEA) is adopted and the accuracy of the simulation results is evaluated against exact analytical solutions. Then, a planar litz structure is presented. Some definitions and guidelines are established, which form the basis to design a planar litz conductor. It can be constructed by dividing the wide planar conductor into multiple lengthwise strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire. Each strand is subjected to the magnetic field everywhere in the winding window, thereby equalizing the flux linkage. 3D FEA is utilized to investigate the impact of the parameters on the litz performance. The experimental results verify that the planar litz structure can reduce the AC resistance of the planar windings in a specific frequency range. After that, some important issues related to the planar boost inductor design are described, including core selection, winding configuration, losses estimation, and thermal modeling. Two complete design examples targeting at volume optimization and winding parasitic capacitance minimization are provided, respectively. This work demonstrates that planar litz conductors are very promising for high frequency planar magnetic components. The optimization of a planar inductor involves a tradeoff between volumetric efficiency and low value of winding capacitance. Throughout, 2D and 3D FEA was indispensable for thermal & electromagnetic modeling. / Master of Science

Les composants magnétiques planaires (inductance et transformateur) occupent une place importante dans certains circuits intégrés utilisés en haute fréquence. Leur miniaturisation et leur intégration vont de pair avec celles des circuits électroniques qui évoluent constamment surtout pour les appareils portables. Quelques travaux scientifiques ont permis d’identifier les différents mécanismes à l’origine de pertes dans les composants magnétiques planaires, afin de les limiter. Les pertes dans les enroulements sont classiquement prises en compte par une résistance r(f) fonction de la fréquence. La détermination, à partir des paramètres S obtenus par mesure ou simulation, de la résistance r(f) constitue à ce jour un sujet d’étude à part entière, les paramètres S étant les seuls paramètres que l’on peut obtenir au-delà de la centaine de MHz. Pour contribuer à la résolution de ce problème, nous avons proposé une méthode prenant en compte toutes les pertes dans le bobinage. Cette méthode de détermination de la résistance en fonction de la fréquence se fait dans trois domaines de fréquence : - en très basse fréquence, la rDC est obtenue par calcul ou mesurée à l’aide d’un matériel basse fréquence, - aux "moyennes fréquences" lorsque les impédances R et Lω ne sont pas trop différentes, les phénomènes capacitifs pouvant être négligés, - aux résonances en très haute fréquence. L’application de cette méthode sur trois structures différentes (inductance à air de plusieurs spires, à air à une spire en oméga et à une couche de matériau magnétique) a permis de : - observer une bonne corrélation entre simulation et mesure, -valider l’évolution des pertes en fonction de la fréquence, -séparer les effets de peau et de proximité, -séparer les pertes fer et les pertes cuivre pour une inductance à couche magnétique / Planar magnetic components (transformer and inductor) have become a big part in some integrated circuits used in high frequency. Miniaturization and integration of magnetic components go hand in hand with the ones of electronics that constantly evolves especially for portable devices. A few scientific studies have identified the different mechanisms of losses in planar magnetic components. Winding losses are generally taken into account using a resistance r(f) versus frequency.The use of scattering parameters S to determine resistance r(f) represents a comprehensive research project ; S parameters that can be obtained either by measurement or by simulation, are the only parameters which one can get at high frequencies (above 100MHz). To solve this problem, we have proposed a method taking into account all winding losses. Our approach for determining r(f) has to be applied in 3 frequency domains: - at very low frequency, r(f) = rDC and its value is either calculated or measured using low frequency equipment, - in the middle frequency range, capacitive coupling can be neglected while impedances R and Lω are in the same order of magnitude, - at very high resonance frequencies.This method has been implemented for 3 different structures (coreless inductor with several turns of coil, Omega shape coreless inductor with one turn and inductor with a magnetic layer) leads to : - observe a good correlation between simulation and measurement, - validate the evolution of losses versus frequency, - separate skin effects and proximity effects, - separate iron losses and winding losses