SA l'actualitat les societats industrials avançades basen el seu desenvolupament en les noves Tecnologies de la Informació i les Comunicacions (TIC). Però aquestes tecnologies són molt sensibles a la qualitat i continuïtat del seu subministrament d'energia elèctrica. Per aquest motiu els Sistemes d'Alimentació Ininterrompuda (SAI) i, per tant, els onduladors, estan agafant un nou protagonisme com a elements fonamentals de la nova societat de les TIC.Els equipaments de les TIC són en la seva totalitat equips electrònics que es comporten com a càrregues no lineals per a la xarxa elèctrica que els alimenta. Les càrregues no lineals consumeixen intensitats no sinusoïdals que en el cas d'ésser alimentades per SAI originen una distorsió harmònica de l'ona de tensió sinusoïdal de sortida. En aquests moments els SAI presents al mercat presenten una Distorsió Harmònica Total (THD) no inferior al 5% quan alimenten càrregues no lineals. Disminuir aquesta distorsió és l'actual repte en el disseny dels onduladors dels SAI.El present treball proposa una sèrie de tècniques de control, per tal d'aconseguir onduladors amb una molt baixa taxa de distorsió harmònica, basades en una nova metodologia de control no lineal provenint de la teoria del control en mode lliscant. La principal aportació del control en mode lliscant és la seva robustesa davant les pertorbacions i, per tant, sembla una tecnologia de control perfectament adaptada per a respondre a les càrregues no lineals de les TIC. La principal dificultat de l'aplicació pràctica dels controls que s'estudien en el present treball és la necessitat d'efectuar els càlculs necessaris amb una elevada velocitat per tal d'aconseguir freqüències d'execució de l'algoritme de control no inferiors a 40 kHz.En el present treball s'han dissenyat i construït els prototipus necessaris per tal d'implementar els algoritmes de control estudiats perquè siguin executats en un Processador Digital de Senyal (DSP) amb una freqüència d'execució prou elevada per tal d'aconseguir una distorsió harmònica total (THD) extraordinàriament baixa alimentant càrregues totalment no lineals. Es creu sincerament que no existeix, en aquests moments, al mercat cap altre ondulador amb les característiques aconseguides. / Nowadays, advanced industry societies base their development on Information Technologies and Communication (ITC). But these technologies are very sensitive to quality and continuity of power supply. For this reason Uninterruptible Power Supply (UPS) and, in fact, inverters are taking the chief role in fundamental elements of new societies of ITC.ITC equipment is totally electronics and their behaviour is like a nonlinear load for electrical grid supplying them. Nonlinear loads consume non-sinusoidal currents that in case they are supplied by an UPS produce harmonic distortion of the voltage output wave. Nowadays, UPS in the market achieve a Total Harmonic Distortion (THD) not less than 5% when supplying nonlinear loads. Decrease this distortion is the goal in UPS inverter design.The present work proposes several techniques in order to obtain a low THD. These techniques are based on a new nonlinear control methodology developed from sliding mode control theory. The main feature of sliding mode control is its robustness in front of perturbations and, therefore, it seems a very interesting method for nonlinear loads of the ITC. However, the main difficulty in the actual application is the need for high speed processors in order to achieve high frequency algorithm execution, not less than 40 kHz.In the present work new prototypes have been designed and constructed to implement the studied control algorithms. Theses prototypes use high speed DSPs in order to achieve a low THD in the inverter supplying nonlinear loads. In the market does not exist a similar inverter with similar features like ones developed in this work.

L'acquisition de l'aimantation dans les sédiments est régit par une somme de processus complexes et souvent interactifs, pouvant introduire des biais directionnels lors de la reconstitution du signal géomagnétique, en particulier des erreurs d'inclinaison. De telles erreurs peuvent mettre en doute l'utilisation de la paléovariation séculaire présumée du champs géomagnétique, révélée par l'ARN des sédiments. Les phénomènes à l'origine de ces erreurs sont principalement liées aux processus de dépôt des particules magnétiques et/ou à la compaction. Ces phénomènes affectent parallèlement la fabrique du sédiment et son anisotropie magnétique. Grâce à l'utilisation de l'anisotropie de susceptibilité anhystérétique (ASA). couplée à la technique plus classique d'anisotropie de susceptibilité magnétique (ASM), une méthode de détection et de correction des erreurs d'inclinaison a été mise au point. L'étude a porté sur un certain nombre de carottes océaniques et continentales présentant des anomalies d'inclinaisons de l'aimantation rémanente naturelle par rapport à la valeur attendue du champ géomagnétique. Des études de minéralogie magnétique ainsi qu'une technique expérimentale de resédimentation sous champ a permis d'estimer les rôles respectifs des propriétés intrinsèques au sédiment (nature, taille, et forme des particules magnétiques) et des influences perturbatrices extérieures (bioturbation, taux de sédimentation, etc ... ) sur l'acquisition de la fabrique et la création des erreurs d'inclinaison de l'ARN. Par ailleurs, l'utilisation de l'ASM sur des sédiments déformés provenant de la région du point triple du Chili a permis de détecter les directions des axes principaux de la déformation. L'origine et l'évolution de l'anisotropie sont discutées en fonction du contexte géodynamique régional.

Many methods for EMI suppression have been developed in the last fifty years, most of them, showing a hardly change in its implementation. Traditional tools for EMI suppression are related to the use of filters, shielding techniques and new methods for layout improvement. These hardware techniques are normally supported with waveform shapes having themselves a lower spectral content. This kind of signals makes part of a different concept of EMI suppression that consists of limiting the spectral content in the signal itself. When possible, just waveforms with a lower spectral content should be used, this way making easier, simpler and cheaper the use of filters and other suppression means. In this line, EMI-reduction techniques such a Spread Spectrum Clock Generation (SSCG) are contributing to eliminate or limit the problem at the root, that is, at the signal itself.This thesis is developed in several parts, corresponding to different chapters. A summary of these chapters is presented onwards:After introduction in chapter 1, a wide theoretical development of the modulation and related concepts are presented in chapter 2. It is explained generically all aspects related to the modulation and particularly, to the frequency modulation. Main parameters of frequency modulation are presented and explained in detail and how practical considerations may affect to the theoretical behaviour of these parameters. Because the theoretical part of this thesis is completely based on the fundamentals of Fourier Transform, a sufficient explanation was thought to include for its right understanding . Finally, all this knowledge is summarized in a computational algorithm (MATLAB environment), capable of generating any frequency modulation of a sinusoidal carrier and the corresponding spectral components resulting from the modulation process.Chapter 3 takes profit of the results obtained in Chapter 2 where it is possible to obtain the theoretical behaviour of the different modulation profiles of interest: sinusoidal, triangular, exponential and mixed waveforms. This way, chapter 3 is intended to completely understand and analyze the theoretical behaviour of these modulation profiles and be quantified according to several significant measure parameters. Afterwards, a comparison of these modulation profiles is carried out by means of the measure parameters defined previously. A proposal of control for a real power converter and theoretical considerations to apply a certain SSCG method to switching power converters are also included in this chapter. After all aspects of frequency modulation by means of SSCG methods have been theoretically developed, it is mandatory the verification of the theoretical conclusions through an experimental test plant. Chapter 4 starts with the description, theoretical calculation and physical implementation of this test plant. Most practical considerations are here dealt with, like the influence of the Spectrum Analyzer's Resolution Bandwidth (RBW) on the measured EMI, a proposal of a practical method to select a valuable SSCG technique applied to Switching Power Converters, comparative measurements of conducted EMI within the range of conducted emissions (0 Hz 30 MHz) and a proposal about SSCG as a method to avoid interfering a certain signal.Chapter 5 summarizes the whole conclusions gathered through the previous chapters and, finally, chapter 6 lists references related to the thesis, separated into different thematic groups.