Dissertations / Theses on the topic 'Conducted and radiated EMI'

La transition vers le véhicule électrique (VE), motivée par les politiques de décarbonation des transports et les avancées technologiques significatives en matière de stockage et de conversion de l'énergie électrique va se poursuivre dans les décennies à venir. En outre, les futurs chargeurs embarqués (On Board Charger - OBC) bidirectionnels en puissance vont contribuer à une plus grande stabilité du réseau, à l'effacement des pointes, voire même à améliorer l'intégration des ressources énergétiques renouvelables : on parle du concept "véhicule-à-réseau" (V2G). Cela signifie que non seulement le nombre de VE augmentera, mais aussi leurs temps de charge et de décharge connectés au réseau.Les besoins de compacité des équipements, favorisés par la disponibilité de composants à grande vitesse de commutation (SiC GaN) ont incité les constructeurs à accroitre les fréquences de fonctionnement des chargeurs embarqués ( > 50-100 kHz) avec comme corolaire l'augmentation de leurs émissions électromagnétiques conduites et rayonnées. En conséquence, ces sources de bruit restent connectées au réseau et fonctionnent durant des périodes prolongées, ce qui rend nécessaire d'anticiper de potentiels problèmes de compatibilité électromagnétique (CEM) dans les réseaux d'énergie : c'est le propos général de ce travail.L'un des objets de cette thèse concerne la méthode normalisée de mesure des émissions conduites dans laquelle l'impédance de mesure du bruit via le réseau de stabilisation de l'impédance de ligne (RSIL) n'est pas toujours représentative de l'impédance du réseau BT, ni évidemment de ses possibles fluctuations. Ainsi, les différents systèmes de mise à la terre fournis-sent des chemins présentant des impédances HF différentes qui peuvent modifier le niveau des émissions. Par conséquent, l'écart entre la configuration normative avec RSIL et l'impédance réelle au point d'accès du réseau électrique peut impacter l'efficacité du filtrage CEM, entraînant de potentiels dysfonctionnements dans les systèmes voisins et/ou connectés sur le même réseau.Le besoin d'analyse des variations d'impédance et les conséquences sur les filtres CEM nous ont conduit à développer et mettre en œuvre une méthodologie pour mesurer l'impédance HF de la terminaison de bruit en fonctionnement sous tension réseau nominale et en l'absence du RSIL. Cette approche permet de mesurer l'impédance en ligne de divers équipements et alimentations, en particulier le réseau de distribution. Partant de ces observations, l'étude de l'impact de l'impédance réelle du réseau sur le volume optimisé d'un filtre CEM a été abordé au travers de scénarios où différents niveaux normatifs ont été considérés.Afin d'examiner les émissions conduites causées par notre prototype de chargeur embarqué bidirectionnel dans un environnement contrôlé sans RSIL, un micro-réseau relié au réseau réel via un transformateur d'isolation a été réalisé. Ceci nous a permis de contrôler ses paramètres : impédance de source, longueur des câbles, système de mise à la terre et de maîtriser les variations d'impédance dues aux charges localement connectées. Les émissions conduites ont été ensuite mesurées et analysées en différents points du micro-réseau selon différentes configurations (régime de terre et différentes charges sur le micro-réseau).Parallèlement, un modèle fréquentiel du micro-réseau a été établi avec une nouvelle approche basée sur l'utilisation d'un solveur de type SPICE et sur l'acquisition expérimentale d'impédances élémentaires, permettant une simulation plus rapide pour des grands systèmes. Ce travail a été suivi par des procédures de vérification rigoureuses pour assurer la précision et la fidélité du modèle. Un modèle comportemental de type « boîte noire » a été développé pour l'OBC, définissant la source de bruit et ses impédances. Il est ainsi possible de simuler les ni-veaux de courant parasites en tout point du micro-réseau, quelque soit les charges connectées
The transition to electric vehicles (EVs), driven by policies to decarbonize transport and significant technological advances in electrical energy storage and conversion, will continue over the coming decades. What's more, future on-board chargers (OBCs) with bidirectional power supply will contribute to greater grid stability, peak-shaving, and even improved integration of renewable energy resources: we're talking about the "vehicle-to-grid" (V2G) concept. This means that not only will the number of EVs increase, but also their charging and discharging times when connected to the grid.The need for compact equipment, favored by the availability of high-speed switching components (SiC GaN), has prompted manufacturers to increase the operating frequencies of OBCs (> 50-100 kHz), with the corollary of increasing their conducted and radiated electromagnetic emissions. As a result, these noise sources remain connected to the grid and operate for extended periods, making it necessary to anticipate potential Electromagnetic Compatibility (EMC) problems in energy networks: this is the general aim of this work.One of the subjects of this thesis concerns the standardized method of measuring conduct-ed emissions, in which the noise measurement impedance via the Line Impedance Stabilization Network (LISN) is not always representative of the impedance of the LV network, nor of course of its possible fluctuations. Thus, different grounding systems provide paths with different HF impedances, which can alter the level of emissions. Consequently, the discrepancy between the normative configuration with LISN and the actual impedance at the point of access to the power network can impact the effectiveness of EMC filtering, leading to potential malfunctions in neighboring systems and/or those connected to the same network.The need to analyze impedance variations and their consequences on EMC filters led us to develop and implement a methodology for measuring the RF impedance of the noise termination while operating at nominal mains voltage and in the absence of the LISN. This approach makes it possible to measure the line impedance of various equipment and power supplies, in particular, the distribution network. Based on these observations, the study of the impact of actual network impedance on the optimized volume of an EMC filter was approached through scenarios where different normative levels were considered.In order to examine the conducted emissions caused by our prototype bidirectional on-board charger in a controlled environment without LISN, a microgrid connected to the real net-work via an isolation transformer was built. This enabled us to control its parameters: source impedance, cable length, grounding system and to control impedance variations due to locally connected loads. Conducted emissions were then measured and analyzed at various points on the microgrid, according to different configurations (grounding regime and different loads on the microgrid).In parallel, a frequency model of the microgrid was established using a new approach based on the use of a SPICE-type solver and the experimental acquisition of elementary impedances, enabling faster simulation for large systems. This work was followed by rigorous verification procedures to ensure model accuracy and fidelity. A "black box" behavioral model has been developed for the OBC, defining the noise source and its impedances. This makes it possible to simulate parasitic current levels at any point in the microgrid, whatever the connected loads.As a result, the model of the entire system has enabled us to analyze impedance variations and conducted emissions in an extended version of the realized system. The thesis will present a synthesis of the results

Power factor correction (PFC) converter is a species of switching mode power supply (SMPS) which is widely used in offline frond-end converter for the distributed power systems to reduce the grid harmonic distortion. With the fast development of information technology and multi-media systems, high frequency PFC power supplies for servers, desktops, laptops and flat-panel TVs, etc. are required for more efficient power delivery within limited spaces. Therefore the critical conduction mode (CRM) PFC converter has been becoming more and more popular for these information technology applications due to its advantages in inherent zero-voltage soft switching (ZVS) and negligible diode reverse recovery. With the emerging of the high voltage GaN devices, the goal of achieving soft switching for high frequency PFC converters is the top priority and the trend of adopting the CRM PFC converter is becoming clearer. However, there is the stringent electromagnetic interference (EMI) regulation worldwide. For the CRM PFC converter, there are several challenges on meeting the EMI standards. First, for the CRM PFC converter, the switching frequency is variable during the half line cycle and has very wide range dependent on the AC line RMS voltage and the load, which makes it unlike the traditional constant-frequency PFC converter and therefore the knowledge and experience of the EMI characteristics for the traditional constant-frequency PFC converter cannot be directly applied to the CRM PFC converter. Second, for the CRM PFC converter, the switching frequency is also dependent on the inductance of the boost inductor. It means the EMI spectrum of the CRM PFC converter is tightly related the boost inductor selection during the design of the PFC power stage. Therefore, unlike the traditional constant-frequency PFC converter, the selection of the boost inductor is also part of the EMI filter design process and EMI filter optimization should begin at the same time when the power stage design starts. Third, since the EMI filter optimization needs to begin before the proto-type of the CRM PFC converter is completed, the traditional EMI-measurement based EMI filter design will become much more complex and time-consuming if it is applied to the CRM PFC converter. Therefore, a new methodology must be developed to evaluate the EMI performance of the CRM PFC converter, help to simplify the process of the EMI filter design and achieve the EMI filter optimization. To overcome these challenges, a novel mathematical analysis method for variable frequency PFC converter is thus proposed in this dissertation. Based on the mathematical analysis, the quasi-peak EMI noise, which is specifically required in most EMI regulation standards, is investigated and accurately predicted for the first time. A complete approximate model is derived to predict the quasi-peak DM EMI noise for the CRM PFC converter. Experiments are carried out to verify the validity of the prediction. Based on the DM EMI noise prediction, worst case analysis is carried out and the worst DM EMI noise case for all the input line and load conditions can be found to avoid the overdesign of the EMI filter. Based on the discovered worst case, criteria to ease the DM EMI filter design procedure of the CRM boost PFC are given for different boost inductor selection. Optimized design procedure of the EMI filter for the front-end converter is then discussed. Experiments are carried out to verify the validity of the whole methodology.
Ph. D.

With the development of power electronics, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) issues have become more and more important for both power converter designers and customers. This dissertation studies EMI noise emission characterization and modeling in power converters. A modular-terminal-behavioral (MTB) equivalent EMI noise source modeling approach is proposed. This work is the first to systematically develop a 3-terminal EMI noise source model for a switching phase-leg device module. Each module is modeled as pairs of equivalent noise current sources and source impedances. Although the proposed MTB modeling approach applies the linear circuit theory to a semiconductor switching device, which exhibits nonlinear behavior during switching transients, the analysis and experiments show that the nonlinearity has negligible practical effect on the modeling methodology. The validation range of the modeling methodology has been analyzed. One of the differences between the proposed MTB model and the other state-of-the-art models is that the MTB model characterizes and predicts the CM and DM noise simultaneously. The inseparable high-frequency CM and DM noise characteristics contributed by the source impedance and propagation path are analyzed. A comprehensive evaluation of different EMI noise source modeling approaches according to the criteria of accuracy, feasibility and generality has been presented. Results show that the MTB modeling approach is more accurate, feasible and general than other approaches. The modular and terminal characteristics of the MTB noise source model are verified in two more complicated cases. One example is the application of the MTB equivalent source model in a half-bridge AC converter with variable switching conditions. Although the MTB model is derived under a certain operating condition, the models under different conditions can be combined together to predict the EMI noise for the converter with variable switching conditions. Another example is the application of the MTB equivalent source model in multi-phase-leg converters. The EMI noise of a full-bridge converter is predicted based on the MTB equivalent source model of one phase-leg module. The implementation procedures and results for both applications are verified by the experiment. The applicability of the MTB model in different type of converters is discussed. Based on the MTB model, EMI noise management is explored. The parametric study based on the MTB model is demonstrated by selecting DC-link decoupling capacitors for voltage source converter (VSC). The EMI effect of a decoupling capacitor for a device s safe operation is analyzed, and this analysis shows the terminal characteristics of the MTB model. Both the EMI and voltage overshoot are predicted by the MTB model. A completed converter-level EMI model can be derived based on the noise source model and propagation path model. This model makes it possible to optimize the EMI filter design and study the EMI noise interactions between converters in a power conversion system.
Ph. D.

The phenomena causing the production and spreading of unwanted electromagnetic emissions arising from electrical or electronic devices, apparatuses and systems have been widely investigated over the last decades and reported in the relevant scientific literature. As a consequence of this, nowadays, the electromagnetic compatibility techniques, which limit the undesirable effects of these emissions, are very popular and of ever-increasing importance both in environmental and industrial contexts. The present thesis focuses on conducted electromagnetic emissions generated by power electronic modules making use of active devices operating with high switching frequency, which today are commonly utilized in a lot of sectors: aerospace, commercial, industrial, residential, telecommunication, transportation, utility systems. The onerous operating conditions of such modules, caused by high values of voltages and electric currents and very short switching times of active devices, make essential, in order to reach an efficient and economic use of materials and components, as well as a reliable and durable use of devices themselves, to carry out an accurate preliminary analysis of the mechanisms resulting in unwanted electromagnetic couplings between the various module components. Indeed, due to the unavoidable presence of parasitic inductances and capacitances and of extremely steep waveforms, electrical signals frequently originate inside the modules with high peak values and exasperated temporal dynamics, which strongly restrict the field of application of the modules themselves. For the sake of concreteness, the analysis of above described phenomena has been worked out on a power electronic module prototype made kindly available by STMicroelectronics, one of the world-leading companies in such field. After a first phase during of which have been individuated and computed the values of the most critical parasitic elements, by means of a theoretical investigation supported by suitable software tools, attention has been paid to how to reduce such values and improve the overall performance of the module. In this connection, some useful techniques to reduce significantly the undesirable emissions have been individuate and successfully applied to the prototype, so obtaining an optimized module from the electromagnetic emission point of view.

Electromagnetic compatibility and compliance with relevant standards is imperative for commercial success for any type of electronic equipment. Since more and more electronics are constantly added into today’s vehicles, this is a highly significant matter in the automotive business. The primary source of electric energy in an on-road vehicle is typically a 12 or 24 volt battery; this makes voltage step down converters ubiquitous in virtually any automotive electronic system. In strive for ever more environmental friendly and energy efficient solutions a switch mode power supply is most often the given choice when it comes to the task of voltage conversion. However, the use of switch mode power supplies presents a new set of challenges when it comes to successfully comply with the electromagnetic emission standards. Knowledge and understanding about how different design parameters impact on EMC performance is key when few prototype runs and short time to market lies in focus. This text will investigate just how different layout design parameters affect the radiated emissions from a buck converter. Emphasis lies on radiated emissions in the lower frequency range up to a few MHz. Both computer simulations and practical measurements indicate the same thing; in the lower part of the frequency spectrum, when measured according to CISPR 25, radiated emissions from buck converters are dominated by voltage driven mechanisms. Along the way we will see how PCB layout alone can be responsible for differences in measured radiated emission levels of well over 20 dB.

This thesis develops a novel method to predict radiated emissions measurements. The techniques used are based on standard Electromagnetic Compatibility (EMC) qualification test methods. The empirical data used to formulate the final results was restricted to pertinent data protocol waveforms however the entire method may be applied to any waveforms for which empirical radiated emissions have been measured. The method provides a concise means for predicting worst case radiated emissions profiles based on empirical measured data.
M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering

Measurement-based behavioral electromagnetic interference (EMI) models have been shown earlier to accurately capture the EMI behavior of switched power converters. These models are compact, linear, and run in frequency domain, enabling faster and more stable simulations compared to the detailed lumped circuit models. So far, the behavioral EMI modeling techniques are developed and applied to the converter's input side only. The resulting models are therefore referred to as "terminated EMI models". Under the condition that the output side of the converter remains fixed, these models can predict the input side EMI for any change in the impedance of the input side network. However, any change at the output side would require re-extraction of the behavioral model. Thus the terminated EMI models are incapable of predicting the change in the input side EMI due to changes at the output side of the converter or vice versa. The above mentioned limitation has been overcome by an "un-terminated EMI model" proposed in this dissertation. Un-terminated EMI models are developed here to predict both the common-mode (CM) and the differential (DM) noise currents at the input and the output sides of a motor-drive system. The modeling procedure itself has been simplified and now requires fewer measurements and results in less noise in the identified model parameters. Both CM and DM models are then combined to predict the total noise in the motor drive system. All models are validated by experiments and their limitations identified. A significant portion of this dissertation is then devoted to the application of behavioral EMI models in the design of EMI filters. Comprehensive design procedures are developed for both DM and CM filters in a motor-drive system. The filters designed using the proposed methods are experimentally shown to satisfy the DO-160 conducted emissions standards. The dissertation ends with a summary of contributions, limitations, and some future research directions.
Ph. D.

Les convertisseurs de puissance sont largement utilisés de nos jours dans des applications qui demandent une grande autonomie énergétique, comme par exemple ceux qui sont alimentés par des batteries. En particulier, les amplificateurs de type Class-D sont fréquemment utilisés dans les applications audio. Ces amplificateurs commutés ont une architecture ressemblante à celle d'un convertisseur DC-DC, ce qui les permet d'avoir une efficacité énergétique élevée. Cependant, leur inconvénient majeur est la forte émission en perturbations électromagnétiques (EM). Cela peut causer des problèmes de conformité avec les normes de compatibilité électromagnétique (CEM), ou bien perturbé le bon fonctionnement des applications électroniques qui l'entour. Pour cela, ils existent de nombreuses études qui permettent de réduire les émissions d'un amplificateur de Class D. Cependant, cela n'est pas suffisant pour retirer le filtre de CEM. Il est donc nécessaire d'optimiser ces filtres et de faciliter leurs conceptions. Ceci est le but de la présente thèse et il est divisé en quatre grandes parties. La première partie commence par développer une technique de modélisation dans le domaine fréquentiel. Cette technique qui est basée sur la détermination et la manipulation des matrices d'impédances a comme but de simuler et prédire les perturbations EM générées par un amplificateur de Class D. Tous les aspects théoriques de la méthode ont été développés. Ensuite, une application pratique sur un système de Class D dédié à la téléphonie mobile nous a permis de valider la méthode jusqu'à une fréquence de 100 MHz. Un amplificateur de Class D est une source de perturbation aussi bien sur les rails d'alimentation que sur les rails de sortie. Pour cela, le filtre de CEM est nécessaire sur les rails de l'alimentation comme il y est en sortie. Néanmoins, un filtre correctement construit doit être conçu en prenant en compte l'impédance de la charge qui est la batterie dans ce cas. Pour cela, la deuxième partie a pour objectif la mesure de l'impédance de la batterie sur la gamme de fréquence considérée. Ainsi, une technique de mesure d'impédance de batterie en utilisant un impédance mètre est développée. Ensuite, une application expérimentale sur un convertisseur DC-DC et une batterie nous a permis de valider la procédure de mesure. La troisième partie s'est focalisée sur l'optimisation du filtre de CEM. Le modèle fréquentiel développé dans la première partie est intégré dans une boucle d'optimisation basée sur un algorithme génétique. L'optimisation inclus plusieurs critères dans sa fonction objective qui sont l'augmentation de la capacité du filtre à réduire les émissions EM, la diminution des pertes supplémentaires due à l'utilisation du filtre et finalement le gain du filtre dans la bande de fréquence du signal audio. Cette étude est poursuivie par une validation expérimentale. La quatrième et la dernière partie étudie et quantifie les impacts du filtre de CEM sur la qualité audio de l'amplificateur. En effet, le filtre de CEM est l'un des chemins propagation du signal audio. Par suite, tout comportement non linéaire du filtre conduit à la distorsion du signal audio. Pour cela, cette partie est dédiée à la modélisation et la simulation des composants passifs contenant un matériau magnétique. En particulier, l'étude s'est focalisée sur la modélisation des perles de ferrite en utilisant le modèle de matériaux magnétiques Jiles-Aterthon. Les résultats de simulations sont comparés avec la mesure dans le domaine temporel et fréquentiel. En plus, le calcul du taux de distorsion harmonique nous a permis de valider le modèle sur une large plage d'amplitude
Switching power management circuits are widely used in battery powered embedded applications in order to increase their autonomy. In particular, for audio applications, Class-D amplifiers are a widespread industrial solution. These, have a similar architecture of a buck converter but having the audio signal as reference. The switching nature of these devices allows us to increase significantly the power efficiency compared to linear audio amplifiers without reducing the audio quality. However, because of the switching behavior, Class-D amplifiers have high levels of electromagnetic (EM) emissions which can disturb the surrounding electronics or might not comply with electromagnetic compatibility (EMC) standards. To overcome this problem much architecture appeared in the state of the art that reduces the emissions, however, this has never been enough to remove electromagnetic interference (EMI) filters. It is then useful to optimize these filters, thus, it has been set as the goal of this PhD thesis. The latter has been divided to four main axes which can be resumed by the following. First, this work started by developing a frequency domain modeling method in order to simulate and predict the EMI of Class-D amplifiers in the final application. The method is based on system to block decomposition and impedance matrix modeling and manipulation. After providing all the theoretical background, the method has been validated on integrated differential Class-D amplifier. The experimental measurements have permitted to validate the method only up to 100MHz. However, this is sufficient to cover the conducted EMC frequency band. Second, the EMI at the supply rails of Class-D amplifiers has been treated. As the battery is often the same power supply for all applications in an embedded system, an EMI filter or a decoupling capacitor is needed to prevent the noise coupling by common impedance. Designing this filter needs the knowledge of the battery impedance at the desired frequencies. Therefore the present work dealt also with measuring the high frequency impedance of a battery. Afterwards, an experimental validation has been carried on with a DC-DC converter and a Class-D amplifier. The developed model allows a virtual test of the switching device in the final application. However, it is more useful if the model is able to help the system integrator in designing filters. Thus, third, the model has been implemented in an optimization loop based on a genetic algorithm in order to optimize the filter response, and also, reduce the additional power losses introduced by an EMI filter. The optimization search space has been limited to the components available on the market and the optimization result is given as component references of the optimal filter referring to the optimal solution found. This procedure has been validated experimentally. Finally, EMI filters often are constituted by magnetic components such as ferrite beads or inductors with magnetic cores. Thus, introducing the EMI filter in the audio path, adds a nonlinear behavior in the audio frequency band. Designing a high quality EMI filter require taking into account this phenomenon and studying its impact of the original amplifier audio performance. Therefore, the Jiles-Atherton model for magnetic materials has been used for ferrite bead modeling. Hereafter, the impact on the time and frequency domain signals has been simulated and compared to measurements. Finally, the total harmonic distortion (THD) has been computed for different signal amplitudes and compared to the THD measured using an audio analyzer. Accurate results have been obtained on a wide range of signal amplitudes. As a conclusion, this work aimed to design optimal EMI filters for Class-D amplifiers. Thus, we dealt with improving their EMI response, reducing their additional power losses and evaluating their impact on the audio quality

The well-established correlation between the high switching di/dt and dv/dt of power semiconductor devices and electromagnetic interference (EMI) generation leads to a trade-off between power converter losses and emission levels; to reduce emissions, the devices are slowed down, incurring greater losses. This thesis addresses in particular the issue of electromagnetic interference (EMI) generation in IGBT-based variable-speed motor drives. The work presented here begins with the hypothesis that it is the higher-order derivatives of IGBT switching waveforms which are most important in determining EMI generation at the frequencies where direct radiation is the dominant mode of emission. Analysis of idealised waveforms shows that by 'rounding the corners' of switching waveforms, it is possible to reduce their high-frequency spectral content with no increase in transition time. High-bandwidth measurements of IGBT switching behaviour are analysed in detail, enabling the trade-off between EMI generation and losses to be quantified, and the critical aspects of the device behaviour for EMI generation to be identified. As with idealised waveforms, itis found that 'corners' of the measured waveforms are responsible for their high-frequency spectral content. The effect of operating conditions on the trade-off between losses and EMI generation is investigated, showing that both temperature and current have significant influence. Informed by the measurements and analysis presented here, an open-loop gate driving technique is developed, allowing programmed voltage profiles to be applied to the gate of an IGBT. By shaping the device switching waveforms to be more 'rounded', it is shown that their high-frequency spectral content may be suppressed by up to 20 dB in the frequency range of interest, with no increase in switching losses.

This thesis presents the conducted electro-magnetic interference (EMI) prediction results for a continuous conduction mode (CCM) power factor correction (PFC) converter as well as the theoretical analysis for the noise generation and propagation mechanisms. In this thesis, multiple modeling and characterization techniques in the medium and high frequency ranges are developed for the circuit components that are important contributors to the EMI noise, so that a detailed simulation circuit for EMI prediction can be constructed. The conducted EMI noise prediction from the simulation circuit closely matches the measurement results obtained by a spectrum analyzer. Simulation time step and noise separator selection are two important issues for the noise simulation and measurement. These two issues are addressed and the solutions are proposed. The conducted EMI generation and propagation mechanisms are analyzed in a systematic way. Two loop models are proposed to explain the EMI noise behavior. The effects of the PFC inductor, the parasitic capacitance between the device and the heatsink, the rising/falling time of the MOSFET VDS voltage, and the input wires are studied to verify the validity of the loop models.
Master of Science

L'augmentation du nombre de fonctions électriques disponibles dans les systèmes embarqués amène de nouvelles contraintes d'encombrement et de masse de leurs alimentations. Pour adresser ces problèmes, la miniaturisation et l'intégration des convertisseurs statiques sont donc des thématiques importantes de recherche qui aboutissent à de nombreuses évolutions technologiques et structurelles dont l'apparition de convertisseurs statiques à fréquence de fonctionnement élevée permettant la réduction des éléments passifs du convertisseurs.Ces avancées s'accompagnent cependant d'une augmentation des niveaux de perturbations électromagnétiques générés par le système. Afin de les diminuer, l'insertion de filtres CEM dans le système est nécessaire. Leurs performances sont fortement liées au contrôle de leurs éléments parasites. Les modèles développés jusqu'à présent concernent pour la plupart les effets conduits et l'évaluation de l'impact des phénomènes rayonnés est souvent ignoré ou au mieux basé sur des modèles simplistes. Un des objectifs de cette thèse est donc d'apporter un degré de complexification plus élevé des modèles de rayonnement des composants magnétiques utilisés dans les filtres CEM, tant par une approche par modélisation numérique que par la mise en oeuvre d'un modèle analytique.Dans un premier temps, une étude poussée du rayonnement magnétique de composants simples, les inductances toriques de mode différentiel, a été réalisée. Cette étude a débouché sur la mise en évidence des paramètres critiques déterminant la topologie du champ magnétique rayonné dans l'environnement proche du composant. Le résultat majeur de cette étude est l'importance de la répartition du bobinage autour du circuit magnétique sur le champ magnétique rayonné. De nouveaux modèles ont été proposés pour permettre la prédiction des champs proches rayonnés pour une gamme de fréquence inférieure à la résonance propre du composant.Par la suite, un modèle analytique fin du rayonnement magnétique des inductances de mode commun a été proposé. Ce modèle permet de déterminer \emph{a priori} le rayonnement magnétique proche du composant. Les études menées par la suite ont permis de relier les effets observés en rayonné au phénomènes conduits qui apparaissent dans ces composants notamment pour expliquer certains effets de transfert de mode (commun/différentiel).Dans une dernière partie, une étude de ces composants en susceptibilité électromagnétique (EM) a été menée. Elle a permis de rendre compte de l'influence d'une onde incidente de champ magnétique sur les composants étudiés et de valider les modèles proposés via une approche basée sur la réciprocité EM: la direction privilégiée de rayonnement est aussi celle de couplage facile pour un champ magnétique externe
The number of electronic devices in embedded systems is constantly increasing and their contribution to volume and weight is a major concern. In order to solve these issues, a large research effort is devoted to volume reduction and power converters' integration. This lead to constant technological evolution including the appearance of high frequency power electronic converters allowing the reduction of the volume of passive components.However, due to the increase of operating frequencies and the minimization of inter-components distances, the electromagnetic radiations generated by these systems become more important. In order to decrease this interference, EMI filters are often necessary. Their performances are often related to the value of parasitic elements in the filter which must therefore be controlled. Nonetheless most of the existing models focus on conducted electromagnetic interference (EMI) and the impact of radiated phenomena is often ignored or greatly simplified. This work will therefore focus on developing highly accurate radiation models for magnetic components commonly used in EMI filters using both numeric and analytic tools.First, the magnetic fields radiated by differential mode (MD) toroidal coils, which belong to the basic magnetic components, will be thoroughly studied. This study highlighted the critical parameters determining the near-field topology. The main result is the discovery of the impact of the winding's layout around the magnetic core on the radiated magnetic field. New models have been developed in order to predict the radiated near field.Then, an accurate analytic model of the the magnetic radiation of common-mode (CM) chokes has been developed. It allows the prediction of the magnetic near-field. The application of the model lead to the correlation between radiated phenomena and conducted effects existing in these components. The importance of the winding on CM to DM mode coupling has therefore been highlighted.Finally, the electromagnetic (EM) susceptibility of these components has been studied. This work describes the influence of an external magnetic field on the components and validates the radiation models developed using the principle of EM reciprocity. It has been shown that the easy directions are the same for both the radiated and the coupled phenomena

Five chapters of this dissertation concentrate on the characterization and cancellation of high frequency parasitic parameters in EMI filters. One chapter addresses the interaction between the power interconnects and the parasitic parameters in EMI filters. The last chapter addresses the characterization, evaluation and design of noise separators. Both theoretical and experimental analyses are applied to each topic. This dissertation tries to explore several important issues related to EMI filters and noise separators. The author wishes to find some helpful approaches to benefit the understanding and design of EMI filters. The contributions of the dissertation can be summarized below: 1) Identification of mutual couplings and their effects on EMI filter performance 2) Extraction of mutual couplings using scattering parameters 3) Cancellation of mutual couplings to improve EMI filter performance 4) Cancellation of equivalent series inductance to improve capacitor performance 5) Analysis of mode transformations due to the imperfectly balanced parameters in EMI filters 6) Analysis of interaction between power interconnects and EMI filters on filter high-frequency performance 7) Modeling and design of high-performance noise separator for EMI diagnosis 8) Identification of the effects of parasitics in boost PFC inductor on DM noise Although all topics are supported by both theory and experiments, there may still be some mistakes in the dissertation. The author welcomes any advice and comments. Please send them via email to shuowang@ieee.org. Thanks
Ph. D.

La charge d’un véhicule électrique constitue un enjeu stratégique pour les constructeurs automobile et forme un réel défi à relever avant de pouvoir comparer ces véhicules à la simplicité d'usage du véhicule thermique. En effet, l’autonomie limitée, la durée de recharge de la batterie, le coût du déploiement d’une infrastructure de charge rapide, l'impact significatif sur les réseaux électriques et le coût élevé de la batterie sont à l’origine de plusieurs projets de recherche axés sur l’optimisation de la chaîne de recharge du véhicule électrique. Afin d’améliorer l'autonomie d'un véhicule électrique, une solution contraignante mais stratégique consiste à embarquer le chargeur dans le véhicule afin d’assurer la conversion ac-dc de l’énergie à partir des prises de courant. Cette solution permet d’augmenter la disponibilité de la charge pour les utilisateurs. En outre, le chargeur embarqué peut réutiliser tout, ou une partie des éléments déjà existants et nécessaires à la propulsion du véhicule. L'idée étant de pouvoir employer certains éléments de la chaîne de traction électrique, déjà embarqués dans le VE (moteur électrique et onduleur de tension), et d’ajouter un filtre d'entrée et un redresseur afin de concevoir le chargeur. Cette solution permet de réduire le coût du chargeur, sa taille ainsi que le volume nécessaire à l'intégration de ses constituants électriques, on parle alors de chargeur intégré à la chaîne de traction. Cependant, la réutilisation de l’électronique de puissance embarquée engendre des problèmes de compatibilité électromagnétique avec d’autres équipements connectés sur le réseau électrique et aussi avec les dispositifs de protection domestique.Le problème majeur à lever est donc, la limitation des émissions conduites et plus particulièrement des courants de mode commun dans une gamme de fréquence importante. Ce projet de thèse a donc, pour objectif, l’amélioration de la disponibilité de la charge actuelle tout en réduisant le volume du filtre CEM passif. Nous cherchons, à travers ces travaux, à identifier des domaines d'améliorations possibles, à proposer des solutions à bas coûts et à intégrer des modifications au niveau de la commande et de la topologie afin d'optimiser le comportement CEM, tant en basses fréquences (0 - 2 kHz) qu’en hautes fréquences (150 Hz- 30 MHz), de ce chargeur embarqué intégré sans isolation galvanique. Les propositions doivent répondre simultanément aux besoins de recharge domestique en monophasé (à 3.7 kW et à 7.4 kW) et rapide en triphasé (à 22 kW et à 43 kW) sans pour autant augmenter le volume ni les coûts engendrés. Ainsi, cinq axes de travail sont étudiés: l’optimisation du comportement CEM (0-2 kHz) du chargeur en monophasé ; l’optimisation du comportement CEM (0-2 kHz) du chargeur en triphasé ; le développement, la mise en œuvre et l’instrumentation de deux bancs expérimentaux exploités pour l’obtention de résultats; la proposition d’une approche de modélisation CEM de la structure qui tient compte du mode commun et du mode différentiel ; et la proposition de solutions pour la réduction des émissions conduites (150 kHz – 30 MHz)
Battery chargers for electric vehicles are classified as on-board or off-board chargers. Off-board chargers are not constrained by size or weight but introduce additional cost to the infrastructure through the deployment of a high number of charging stations. In order to meet the needs of electric vehicle users in terms of charging availability, on-board chargers that achieve ac/dc conversion are retained. Furthermore, on-board chargers are classified as standalone or integrated systems. By reusing parts of the traction power train for charging, the latter reduces the cost of the charger. Disadvantages of integrated systems include electromagnetic compatibility issues and complex control schemes.This work presents the power quality performance analysis and control optimization of an on-board non-galvanically isolated electric vehicle charger integrated to the traction’s power train. In order to be able to evaluate the high frequency conducted common mode emissions (150 kHz - 30MHz) of a power conversion structure, one needs to develop a good current control scheme that establishes a high-quality low frequency behavior (0 - 2 kHz). Therefore, different aspects related to the power factor correction of the single-phase as well as the three-phase charging configurations are studied: the control scheme for the regulation of the charging power, the displacement power factor correction, the suppression of the grid current harmonics and the active damping of the input filter’s resonance. Two experimental test benches are developed using two different technologies (Silicon IGBTs vs. Silicon Carbide Mosfets). Experimental results are provided.This work also presents a comprehensive approach to modeling the CM and the DM EMI behavior of a power electronics structure. This method is applied to the charger in its single-phase and three-phase configurations. The models allow to evaluate the fluctuating internal nodes and to study the effect of various proposed mitigation solutions on the CM emissions. The models are also developed in the intent of being injected into optimization algorithms for the future design of an optimal EMI filter

Ce travail de recherche porte sur l’étude de l’effet du vieillissement par fatigue électrothermique sur la compatibilité électromagnétique des composants de puissance à base de carbure de silicium. Il est axé sur deux grandes parties ; une partie expérimentale et une autre plus orientée modélisation. Sur le plan expérimental, cette thèse étudie l’effet du vieillissement des transistors à base de carbure de silicium utilisés dans les convertisseurs statiques sur les perturbations électromagnétiques générées par ces convertisseurs. La deuxième partie porte sur la modélisation de ces transistors afin d’émuler l’effet de leur vieillissement sur les perturbations électromagnétiques des modules qu’ils composent. Cette dernière étape repose sur une étude de l’évolution des caractéristiques électriques statiques et dynamiques effectuées sur le composant sous test pour extraire les principaux paramètres intrinsèques du transistor de puissance dégradé après les séries de stress appliquées. En effet, ces paramètres intrinsèques dégradés émulent l’effet du vieillissement et sont représentatifs des principaux phénomènes pouvant influencer les convertisseurs de puissance étudiés. De ce fait, le changement de leurs valeurs dans le modèle du dit composant, décrit en VHDL-AMS et implémenté sur le simulateur de type circuit ANSYS SIMLORER, nous permet d’obtenir un modèle d’un tel composant après vieillissement. Cette étape a permis de valider la méthodologie développée pour la simulation des perturbations électromagnétiques conduites d’un composant sain dans un premier temps et d’un composant vieilli dans un second. Globalement, cette approche de modélisation innovante développée dans ce travail permet d’aider les concepteurs des convertisseurs statiques à prédire les perturbations électromagnétiques conduites avant et après vieillissement sans passer par la mesure et ses points faibles. Ceci apporte des informations complémentaires sur l’évolution des signatures CEM de tels modules durant sa durée de vie et d’estimer donc le risque lié au vieillissement des composants
This research work focuses on the electrothermal aging effect on the electromagnetic compatibility of power components based on silicon carbide SiC. It focuses on two major parts ; an experimental part and another more oriented modelization. Experimentally, this thesis studies the aging effect of SiC transistors used in static converters on the electromagnetic interferences EMI generated by these converters. The second part deals with the modeling of these transistors in order to emulate the effect of their aging on the EMI of the modules they compose. This step made it possible to validate the methodology developed for the simulation of the conducted EMI of a healthy SiC MOFSET at first and of an aged SiC MOSFET in a second time. Overall, this innovative modeling approach developed in this work helps the designers of static converters to predict the conducted EMI before and after aging without going through the measurement. This provides additional information on the evolution of the EMC signatures of such modules during its lifetime and thus to estimate the risk associated with the aging of the components

In a short time touchscreens has become one of the most used methods for input to smartphones and other machines such as cash registers, card terminals and ATMs. While the technology change was quick it introduces the possibility of new security holes. Compromising emanations is a possible security hole in almost all electronic equipment. These emanations can be used in a side-channel attack if they leak information that compromise the security of the device. This thesis studies a single-board computer (SBC) with a touchscreen and a smartphone in order to evaluate if any usable information leaks regarding what is done on the touchscreen i.e. where on the screen a user touches. It is shown that the location of a touch can be read out from information leaking through the power cable and wirelessly from the single-board computer. It is also shown that basic information can be read out wirelessly from the smartphone but further testing is required to evaluate the possibility to extract usable information from the device.

With advances in technology and increased design complexity in the automotive industry, Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) issues are becoming increasingly important. An accurate system level analysis is required from an early design stage to detect and mitigate problems at the initial stage. The major difficulty encountered in automotive simulation is to deal with different geometric scales, ranging from a fraction of wavelengths (Printed Circuit Board) to multiple wavelengths (harness). When the problem size becomes larger, traditional full wave solvers like Finite Element Method (FEM), Method of Moment (MoM) or Finite Time Domain Difference (FDTD) lose their efficiency as calculation of domain interactions become computationally costly. There is an opportunity to combine different solvers in a hybrid framework to efficiently analyze such system-level problems. This thesis addresses the challenge and proposes different modelling and simulation methods for EMC test setups using a hybrid approach. The first part of this work is an efficient 2.5D solver development for power distribution network (PDN) analysis of automotive boards. Design of power ground layout of a multi-layered Printed Circuit Board (PCB) is crucial for low noise and stable power supply. 2.5D tools are better suited for early stage PDN analysis over 3D full-wave electromagnetic solvers due to faster simulation times. In this work, a non-orthogonal 2.5D PEEC formulation is proposed, employing quadrilateral mesh elements for efficient simulation of the PDN. Individual stamps for resistance, inductance, capacitance and conductance elements for a unit quadrilateral cell are derived. Further, the methodology is enhanced to capture coplanar coupling through introduction of mutual inductance and capacitive terms between neighboring PEEC cell-pairs. Numerical results demonstrate good accuracy compared to a 3D full-wave commercial tool for layered PCB geometries. The efficiency of the proposed method is benchmarked against commercial solvers. The second part of the work is focused on the model-based simulation methodology for system-level immunity characterization at an early design stage. The Bulk Current Injection (BCI) method is one of the commonly used immunity test for automotive ICs. In this test, a common mode RF current of a specified value is injected into the cable harness using an injection clamp. The DUT functionality is monitored under this RF disturbance over a frequency range typically up to 400 MHz. The simulation framework for BCI test is comprised of a hybrid 2D-3D electromagnetic solver and a circuit solver. First, an accurate circuit model of injection clamp with multiple cables is developed. Although, there are circuit models reported in literature for clamps with a single cable, they do not directly lend themselves to multiple cable formulation. The proposed clamp model is validated with measurements. Then, IC immunity model (ICIM) is inducted into the simulation environment to accurately predict the immunity behavior of an IC. The proposed method is validated by comparing the simulation prediction with the actual BCI measurement. Finally, an approach comprising of Method of Moments and Harmonic Balance method is used to capture the non-linear response of active elements like transistors or diodes in an automotive board. It is demonstrated that a traditional Harmonic Balance approach will fail at high noise voltage levels which may be a likely scenario in many BCI tests with high injection clamp current specifications. A Line-Search intermediate step is introduced to address this issue. Numerical results demonstrate that the proposed method converges to accurate results faster. The third problem is focused on improving the simulation efficiency of a radiation emission (RE) test bench in the automotive application. As the device under test (DUT) and the measuring antenna are electrically far apart, the back scattered field from the antenna is quite minimal and can be neglected. By using the unidirectional coupling between these domains, a substantial reduction in memory requirements and computational time can be achieved in comparison to traditional multi-domain hybrid FEM-MoM. Also further speed up is achieved by reusing the domain-to-domain interaction terms. Next part of this research is focused in finding the source of radiation in the emissions setup. The source of radiation can be from common mode current on the cable harness or from the DUT. A method based on Huygens box is proposed to quantify the radiation from cable and DUT at each frequency. On each cell of the Huygens box the value of electric field computed at the observation point taking the Electric Current (J) and Magnetic Current (M) on that cell as sources and this information on the Huygens box is used to quantify the radiation. Some part of the presented work is used at Simyog, an IISc incubated start-up, to develop a simulation software called Compliance-Scope which allows the designer to predict the EMI/EMC performance of electronic hardware modules at an early design stage

碩士
國立臺北科技大學
電機工程系所
100
The rapid evolution of electronic science and technology innovation yields small and light goods with large capacity and high speed. The small size limits the design space, leading to increasingly serious EMI (electromagnetic interference) problems. EMI is mainly divided into radiation type and conductivity type. Conducted EMI noise passes through the power lines. Hence, EMI in the same power system circuit will interfere with each other through the power lines. Generally, the solution of conducted EMI is to add an LC filter at the supply side entrance. Then, the EMI can be prevented to outflow. In order to solve EMI problem, engineers need to rent expensive equipment, certificated venue and booking measurement time slots. They often take only several normalized inductances and capacitors to go to a lab for testing. If engineers can not figure out the solution of the EMI noise after the testing, they need to prepare other inductances and capacitors next time. This thesis proposes an adjustable conducted EMI filter. The common-mode inductance can be on-line and continuously adjusted. Hence we can find the corresponding ideal filter frequency very soon. With this design, engineers do not to need to spend so much time to go back and forth to the laboratory to do circuit modification. By doing this, EMI issues can be fixed more efficiently.

碩士
國立臺灣科技大學
電子工程系
88
For most electronic engieers, it is a hard work to conquer the EMI problem and yet no systematic method can be followed. In this thesis, we will derive an algorithm to estimate the magnitude spectrum of CM (Common mode) or DM (Differential mode) noise. Also, a suitable EMI filter model will be selected and a program with a friendly user interface to fulfill the functions of the software-based EMI measurement system is developed in Visual Basic. The features of this system include noise measurement, variant EMI filter design, design of the damping circuit for the EMI filter, the estimation of CM/DM noise spectrum, and linear-scaled axis/log-scaled axis transformation, etc. With the proposed system, any user can easily select the functions by clicking on the buttons of items shown on the PC monitor. Therefore, one can quickly obtain the optimum filter configuration and find a simple and effective way to design EMI filter.

碩士
國立臺灣科技大學
電機工程系
93
The purpose of this thesis is to investigate conducted electromagnetic interference issues in two-stage converters. The pre-stage is for power factor correction from AC voltage to DC voltage and the structure is the circuit of conventional bridge rectification with a boost converter added. The post-stage circuit is functioned to transform from DC voltage to the rated DC voltage of load with the structure of flyback converter. According to electromagnetic interference regulations, the problematic electromagnetic interference may delay products reaching the market. If the electromagnetic interference problem analysis and improvement can be controlled before the circuits are done, it will definitely avoid unnecessary re-design or modifying circuits. Cost and time efficiency can both be improved. To reach this goal, this research proposes a systematic analysis and simulation method. At the beginning design stage of switching mode power supplies, conducted electromagnetic interference frequency band leveled at 150kHz~30MHz is considered. According to the actual high-frequency characteristics for each component within the said frequency band, the high-frequency models for active components, passive components and the printed circuit board are established separately. The models are then combined with the line impedance stabilization network model, to accomplish the conducted electromagnetic interference simulation for the circuit system of two-stage converters. Finally, simulated and measured EMI noises are compared. Thus, the problematic electromagnetic interference can be predicted. This is very helpful to save time and cost caused by electromagnetic interference problems.

碩士
國立臺灣大學
機械工程學研究所
98
Adjustable Speed Drive (ASD) system is essential in a variety of electric vehicles. It is different from the traditional gasoline engine vehicles. ASD system is an extra interference of the electric vehicles and the degree of disturbance is also greater than other electronic components. Therefore, it is an important issue to find out how ASD system conducts the intensity of EMI in 150k-30MHz through data simulation at design stage. In this research, ansoft simplrer system-level circuit software is used for simulating the intensity of EMI by conducting of NTU Green Jumper’s ASD system, which also includes IGBT device dynamic model, IPM motor high frequency model, snubber circuit, power line and bus parastic parameter with coupling. Based on the simulation result, ASD system can successfully conduct EMI in 150k-30MHz and the error could be less than 10dB, which confirmed that EMI modeling method can be accurately used at the design stage, and also be the reference for a filter designing. In experimental operation, I made the test in S1 wave isolation room at Automotive Research & Testing Center and obtained frequency domain data after checking background’s interference can meet test requirements.

碩士
清雲科技大學
電機工程研究所
97
Ever since the initial development in 1970’s, the switching mode power supplies have been widely adopted in various electronic apparatus, such as personal computers, laptop computers, printers, digital cameras , mobile phones, … etc. Switching power supplies become essential for modern human life. From the power supply technical point of view, there are several remarkable progresses in the past decades, such as high-efficiency topologies, high performance power semiconductors, various integrated control circuits, and low-loss magnetics, which make the power supply more efficient and reliable. However, accompanying with the technologies of high density PCB layout and high-frequency switching, the noise coupling problem between the PCB wirings and the components are getting more and more serious. The so-called “Electromagnetic Interference” (EMI) has always bothered the power supply engineers. In terms of noise generation and noise coupling, many uncertainties exist inside the power supply system. Most engineers can resolve the EMI issues only by try and error method. In this thesis, an analytic approach to identify the noise amount of an active power factor corrector is proposed, which is great helpful for designing the noise filter. Besides, a common/differential noise separator is adopted to distinguish the noise types, which can be used for efficient filter design. Measurement to identify parasitic parameters of filter components are also included, which illustrates the noise spectrum in different frequency range. Finally a systematic approach is proposed to design a suitable noise filter. Implementation of the noise filter in a 300W hardware is presented to verify the feasibility of the theoretical derivation.

碩士
明新科技大學
電機工程研究所
98
With the developments in high-tech field, the problems of electromagnetic interference are also increasing. When the device becomes faster speed and higher density, the noise is also greater. The electromagnetic noise is likely to make itself broken or the functional output abnormal. The electromagnetic interference can affect environmental equipments by means of transmission medium. Electromagnetic noise can be divided into conducted emission and radiated emission. In this thesis, we study radiated emission by using EMIStream software, and we carve these print circuit boards (PCB) by using PCB prototype machine. With suitable PCB layout, the radiated emission will be reduced.

碩士
中原大學
電機工程研究所
101
To reduce the power density of the power supply, the switching frequency of switching power supply (SPS) is getting high, but also causes the increasing of electromagnetic interference (EMI). This thesis is to develop the EMI filters between the input and output of the PV inverter so as to suppress EMI noise complying with CISPR22 (Comité International Spécial des Perturbations Radioélectriques) ClassB suppression standards. In this study, differential-mode and common-mode separation techniques for suppressing EMI at input and output of the PV inverter are investigated. Three kinds of filter ladders of 1 to 3 are examined with analysis and simulation. Finally, a demonstrated prototype of 500W PV inverter with two-ladder filter at input and three-ladder filter at output is explored to verify the attenuation capability and noise suppression effect. The experimental results are close to the theoretical evaluation and comply with CISPR22 Class B.

碩士
輔仁大學
電子工程學系
95
Abstract The mobile power supply devices were usually lower than 100W in the past . Due to most electronic product functions increase today ,the power requirement is more and more and reach 220W(max) . Both high power and shrinkage space make the 220W power supply design challenge. Therefore, dual-transformers flyback circuit is generally used in the high power supplying product. That can make the space application more efficient and heat dissipated more effectively then reduce the height of the power supply. This paper provide a shift phase method to drive dual-transformer’s MOSFET for improve the loop current which caused by dual-transformer and reduce the EMI interfere/output capacitor. Then we can reduce the EMI component and output capacitors. So total price can be reduced about 1~2 USD and reduce the design cycle time, Also achieve the main goal of reduce product price, size and weight….etc . Both simulating and experimental results are given in detail. Keywords: Conducted EMI, Flyback converter, Shift phase control, Push-pull control.

碩士
國立成功大學
電機工程學系碩博士班
97
This thesis proposes the modified EMI filter for suppressing narrow-band conducted noise. The circuit consists of sorts of passive elements, including the induction winding, capacitors and resistors. By combining the passive elements in series and parallel to produce resonance, the modified EMI filter is made to achieve the narrow-band conducted noise suppression. By designing and adjusting ideal parameters of elements to produce resonance, it achieves to reduce common-mode noise current and differential-mode noise current efficiently of the narrow-band conducted suppression without affecting broad-band conducted noise suppression. This paper further provides to prove the modified EMI filter for suppression of narrow-band conducted noise, which can effectively reduce electromagnetic interference from the narrow-band conducted noise by theoretical analysis added with circuit simulations and results of measured experiments.

碩士
國立臺灣大學
電機工程學研究所
93
Electromagnetic Interference (EMI) has always been a major concern for power electronic circuit design engineers. Despite the progress made in recent years, there is still “black magic” associate with fixing the EMI problems in the industry. Attempts have been made in the past few years to use simulation tools to predict conducted EMI behavior in power electronic circuits and results were reported in research articles. However, the results reported in these articles were obtained in research environment. Doubts were expressed if such results can still be meaningful in a commercial environment. To address such an issue, efforts were spent to investigate the conducted EMI of a commercial 40-Watt 320-KHz 15-volt output high-density DC/DC power module using computer simulation tools. In the thesis, methodology of computer simulation of EMI behavior is outlined. Parasitic elements of importance, including those of the power components, the printed circuit board, and the assembly package, were included in the simulation. IsSPICE was used for time-domain simulation and Fast-Fourier Transform function was used to converter the simulation results into frequency-domain EMI data. It is concluded from the investigation that simulation complexity can be reduced to a practical level without losing the accuracy for frequency range below 10MHz. Although the accuracy is limited, analysis of the results already provides useful information and practical guidance for EMI reduction for the product. For frequency beyond 10MHz, the simulation results deviate significantly from the experimental results. This is not unexpected. Package proximity effects, which are still not fully understood, were not incorporated in the simulation. Further works along this line is needed in the future.

碩士
國立臺灣科技大學
電機工程系
97
The purpose of this thesis is to investigate the generalization of the conducted EMI model developed earlier by Lin [1]. Both measurements and simulation for conducted EMI are performed to verity the high frequency model proposed earlier by Lin [1]. The application circuit is that of boost power factor correctors. Experiment steps: (1) simulation of a boost power factor corrector in operation to identify low frequency problems, (2) including high frequency characteristics in low frequency component models to account for the 150 kHz ~ 30 MHz frequency range of conducted EMI in practical measurements. First, measurements and simulation for each separate component are conducted to verify their impedances and phase curves. The model is included in the circuit to simulate conducted EMI. Finally, simulation and measured EMI noises are compared to investigate whether the model is suitable for the frequency range of conducted EMI or not. The problematic electromagnetic interference can be predicted. Thus, time and cost of circuit design can be reduced. Considering the results of applying high-frequency model by Lin [1], the comparison results show that the EMI of different circuits will have different influence factors, including circuit structure, component characteristics, circuit design, PCB layout, and so on. Therefore, the high-frequency model should be concerned about more parameters, such as working temperatures of components, the permeability of magnetic components, and so on, for designing a further complete high-frequency model. In addition, the factors influencing EMI also include some environmental problems, such as the testing cables of measuring instruments, noise value, and so on. Thus, if the condition mentioned above can be considered, the model will facilitate EMI simulations of circuits.

碩士
長庚大學
電機工程研究所
94
This thesis studies losses locating and conducted EMI analysis of a flyback switching power supply with the assistance of an infrared thermal analyzer. First, a switching mode flyback power supply is implemented as a test target. Then, an infrared thermal analyzer is used for locating the losses of circuit elements in this power supply. Further more, in order to evaluate the conducted EMI affected by heat from losses, the conducted EMI measurement is also made. The test results show that the infrared thermal analyzer is a useful analysis tool for thermal locating of switch power supply. The suppression of conducted EMI by using proper thermal dissipation is possible.

碩士
輔仁大學
電子工程學系
92
A software approximation is proposed to separate the common-mode (CM) and differential-mode (DM) conducted emission for the power line EMI filter design of a switching mode power supply (SMPS). The computerized design environment bases on the LabView test and measurement system. Both the CM and DM noises can be separated using the software algorithm without the hardware implementation. The separation and the EMI filter designe results are compared with the conventional method. The filter designe results and experiment show that the proposed approximation can provide a user friendly and convincible approach for EMI countermeasure and EMC education.

M.Ing.
In power electronics most applications are custom designed. Even though similar topologies are used, each application is designed to fit specific requirements. Presently there is a move towards standard modules that can be connected together to perform the desired power conversion, in much the same way as IC’s have been used for a few decades now. It is important to ensure that the modules can work together without performance degradation. The close proximity of active, passive and logic devices in high power applications dramatically increases the risk of EMI between the various components. This document describes the design and characterisation of a planar conducted RF-EMI power line filter to be used between modules and between modules and power supplies. The filter consists of two sets of transmission lines in parallel. The first is a high permittivity material with nickel conductors, referred to as the attenuator. The second is a set of copper conductors that are placed on the outside of the attenuator. The filter must be able to remove conducted differential mode noise from power line to the module and from the module tot the power line. The filter dimensions are comparable to the wavelengths that have to be attenuated. This allows for a possible combination of RF filtering techniques and power line filtering techniques. The design of the filter and the electromagnetic effects that govern its behaviour is explained. The transfer characteristic of the filter is made possible by the choice of materials and their relation to each other. Each material is discussed and evaluated. Characterisation methods are described and results presented. The influence the materials have on the performance of the filter and the methods and problems of construction of the filter are discussed. The construction of the filter and the commercial processes available are discussed. A prototype filter was built to demonstrate the feasibility of the construction processes. The performance of the prototype filter was then measured. The various test set-ups for different applications are explained. Small signal tests in 50 W systems were used to allow for comparisons with other filter types. The prototype has minimal insertion loss in the pass band and an average slope of attenuation of 40 dB/decade beyond the corner frequency. The corner frequency is at 1 MHz. Transmission line theory is used to develop a distributed element model for the filter using the ABCD-matrix representation of transmission lines. From this matrix an equivalent P-model can be calculated. Applicable assumptions are made to simplify the equations and values for a lumped element P-model is calculated. Both models indicate the importance that the material parameters have on the performance of the simulation results. Good correlation between the measured performance and simulated performance is established. The material parameters are sensitive to temperature. A one-dimensional thermal model is presented to estimate the operating temperature of the filter. It is determined that the attenuation of the filter is primarily determined by the attenuator. Based on the findings, new attenuator designs are made in an attempt to improve the performance of the filter. The small signal measurements of the various designs and the test results under load conditions are compared. A power test is performed. The filter performance varies as the voltage rating is increased. Finally, a temperature characterisation is done. The filter is absorptive and heat is dissipated in both the conductors and the dielectric material. The filter performance is sensitive to the operating temperature. A summary of the technology and the evaluation of this type of filter are presented in the conclusion.