A complete methodology has been proposed to model and evaluate IC packages in the high-speed digital and radio-frequency applications. The package types that are studied in this dissertation include BGAs, TSSOPs and BCCs. In characterization of BGAs, both frequency-domain and time-domain techniques have been applied and compared to each other. It was found that the best strategy was to find a rough coupled transmission-line model in the time domain and refine it through the optimization scheme in the frequency domain. Equivalent lumped model has been further derived from the coupled transmission-line model using the concept of distributed parameters. For RFIC applications, the electrical model of BCC, one type of lead-frame CSP, has been established based on the frequency-domain technique. To evaluate the package performance, an on-chip 50-ohm microstrip line housed in the package has been investigated. The insertion and return losses were analyzed and measured. Excellent agreement has been observed up to Ku band. The package acts as a low-pass filter to cause a cut off for the line above a certain frequency, which was predicted successfully from the established package model. The simulation results also show that BCC exhibits higher cut-off frequency and lower insertion loss in the passband when compared to TSSOP, one of the currently most popular RFIC packages.

<p>Frequency response analysis (FRA) is a method which is used to detect mechanical faults in transformers. The FRA response of a transformer is determined by its geometry and material properties, and it can be considered as the transformer’s fingerprint. If there are any mechanical changes in the transformer, for example if the windings are moved or distorted, its fingerprint will also be changed so, theoretically, mechanical changes in the transformer can be detected with FRA.</p><p>The purpose of this thesis is to partly create a simple model for the ferromagnetic material in the transformer core, and partly to investigate the high frequency part of the FRA response of the transformer winding. To be able to realize these goals, two different models are developed separately from each other. The first one is a time- and frequency domain complex permeability model for the ferromagnetic core material, and the second one is a time- and frequency domain winding model based on lumped circuits, in which the discretization is made finer and finer in three steps. Capacitances and inductances in the circuit are calculated with use of analytical expressions derived from approximated geometrical parameters.</p><p>The developed core material model and winding model are then implemented in MATLAB separately, using state space analysis for the winding model, to simulate the time- and frequency response.</p><p>The simulations are then compared to measurements to verify the correctness of the models. Measurements were performed on a magnetic material and on a winding, and were compared with obtained results from the models. It was found that the model developed for the core material predicts the behavior of the magnetic field for frequencies higher than 100 Hz, and that the model for the winding predicts the FRA response of the winding for frequencies up to 20 MHz.</p>

Terminal models have been used for various power electronic applications. In this work a two- and three-terminal black box model is proposed for electro-magnetic interference (EMI) characterization. The modeling procedure starts with a time-variant system at a particular operating condition, which can be a converter, set of converters, sub-system or collection of components. A unique, linear equivalent circuit is created for applications in the frequency domain. Impedances and current / voltage sources define the noise throughout the entire EMI frequency spectrum. All parameters needed to create the model are clearly defined to ensure convergence and maximize accuracy. The model is then used to predict the attenuation caused by a filter with increased accuracy over small signal insertion gain measurements performed with network analyzers. Knowledge of EMI filters interactions with the converter allows for advanced techniques and design constraints to optimize the filter for size, weight, and cost. Additionally, the model is also demonstrated when the operating point of the system does not remain constant, as with AC power systems. Modeling of a varying operating point requires information of all the operating conditions for a complete and accurate model. However, the data collection and processing quickly become unmanageable due to the large amounts of data needed. Therefore, simplification techniques are used to reduce the complexity of the model while maintaining accuracy throughout the frequency spectrum. The modeling approach is verified for linear and power electronic networks including: a dc-dc boost converter, phase-leg module, and a simulated dc-ac inverter. The accuracy of the model is confirmed up to 100 MHz in simulation and at least 50 MHz for experimental validation. / Ph. D.

Frequency response analysis (FRA) is a frequency-domain method which is used to detect mechanical faults in transformers. The frequency response of a transformer is determined by its geometry and material properties, and it can be considered as the transformer’s fingerprint. If there are any mechanical changes in the transformer, for example if the windings are moved or distorted, its fingerprint will also be changed so, theoretically, mechanical changes in the transformer can be detected with FRA. A problem with FRA is the fact that there is no general agreement about how to interpret the measurement results for detection of winding damages. For instance, the interpretation of measurement results has still not been standardized.The overall goal of this thesis is to try to enhance the understanding of the information contained in FRA measurements. This has been done in two ways: (1) by examining the FRA method for (much) higher frequencies than what is usual, and (2) by developing a new method in which FRA is combined with the ideas of Time Domain Reflectometry (TDR). As tools for carrying out the above mentioned steps, models for the magnetic core and the winding have been developed and verified by comparison to measurements.The usual upper frequency limit for FRA is around 2 MHz, which in this thesis has been extended by an order of magnitude in order to detect and interpret new phenomena that emerge at high frequencies and to investigate the potential of this high-frequency region for detection of winding deteriorations.Further, in the above-mentioned new method developed in this thesis, FRA and TDR are combined as a step towards an easier and more intuitive detection and localization of faults in transformer windings, where frequency response measurements are visualized in the time domain in order to facilitate their interpretation. / QC 20111122

Fast switching operations in IGBTs generate electromagnetic field disturbances, which might cause EMI and functionality issues. For higher frequency characterization, the parasitic inductances and capacitances have to be considered. The characterization of the electromagnetic field disturbances in- and around the converter module could be predicted early in the design. The study involves a high frequency characterization of electric fields (Efield), magnetic fields (H-fields) and the surface currents distribution in a converter module. The high frequency electromagnetic software (CST) was used for the analysis. A given 3D CAD model of an AC/DC converter module was analyzed in CST. The CAD contained IGBT bus-bars interconnections, converter casing, heat sink and other metallic structures. The ACside has six IGBTs and the DC-side has a chopper which has two switches. The IGBTs ONstate and OFF state was modeled with lumped elements. The DC link capacitor was just modeled as lumped elements, while the metallic capacitor casing was included in the 3D model for analyzing the field distribution inside the converter casing. To check the model accuracy, CST models were compared with PEEC (Partial Element Equivalent Circuit) models for simple antenna cases. Using the converter geometry, CST estimates the parasitics and the eventual current, voltage and electromagnetic field distributions for a given excitation signal. The DC-link was excited with a step pulse and the fields were computed. With consideration of specific design details, the modeling approach developed in this study, could be used to construct high frequency models of converter modules for different projects.

This dissertation proposes a modeling methodology for Inductive and Capacitive Voltage Transformers (IVT and CVT) for high-frequency electrical transients analysis, up to 3 MHz. The model construction starts from the VT s sweep frequency test, carried out by a commercial Sweep Frequency Response Analyzer (SFRA) with special connections, in order to obtain its short-circuit Admittance Matrix. The SFRA is designed for another purpose, to detect displacement of windings or fault in the magnetic core of power transformers based on voltage transfer analysis. Therefore, due to this fact, the measured data needs to be corrected and recalculated, through and external routine, to adequately represent the proper and mutual admittance values of the Matrix. After its correction, the Admittance Matrix serves as input data to the Matrix Fitting method, a frequency-response approximation tool by means of modified rational functions, which is part of the Vector Fitting (VF) routine, freely available for non-commercial purposes in MATLAB®. The results are an approximated rational function, in state-space or pole-residue model, and a RLC equivalent network proper to be used in electromagnetic transients analysis software, such as the Alternative Transients Program (ATP). The models validation is accomplished based on the comparison between the transient responses of the created model, through simulation in ATP/EMTP, and the IVTs and CVTs laboratory tests when both are submitted to a step function excitation. / Esta dissertação propõe uma metodologia para a modelagem de Transformadores de Potencial Indutivos (TPIs) e Capacitivos (TPCs) para estudos de transitórios eletromagnéticos em altas frequências, na ordem de até 3 MHz. A obtenção dos modelos inicia através do ensaio de varredura em frequência dos TPs utilizando um Sweep Frequency Response Analyzer (SFRA) comercial por meio de conexões especiais de modo a obter as Matrizes de Admitâncias de curto-circuito. Os fabricantes do SFRA projetaram este equipamento com outro objetivo, o da realização de estudos de transferência de tensão, para detectar possíveis deformações mecânicas ou falhas internas em transformadores de potência. Desse modo, os dados obtidos dessa medição necessitam ser corrigidos e recalculados, através de uma rotina externa, a fim de representar adequadamente os valores das admitâncias próprias e mútuas desta Matriz. Uma vez corrigida, essa Matriz de Admitâncias servirá como entrada para inicializar o método do Ajuste Matricial (Matrix Fitting), que é uma ferramenta fundamental para aproximação da resposta em frequência por funções racionais modificadas que integra a rotina de Ajuste Vetorial, disponível livremente para fins não comerciais no MATLAB®. Como resultado, são obtidas sua função racional aproximada, em modelos de espaço de estados ou de polo-resíduo, e uma rede RLC equivalente complexa, propícia para o uso direto em programas de análises de transitórios eletromagnéticos, como o Alternative Transients Program (ATP). A validade dos modelos criados foi verificada por meio da comparação das respostas transitórias dos equivalentes gerados, através de simulações no EMTP/ATP, com os ensaios feitos em laboratório e em campo em TPIs e TPCs quando submetidos a uma excitação com uma função degrau.

Dans le cadre du dimensionnement des systèmes de conversion statique d’énergie implantés dans des réseaux électriques, il est important de respecter certaines normes harmoniques. Pour caractériser celles-ci, on doit utiliser des approches des modélisations fréquentielles : soit numérique, soit semi-analytique. La deuxième est préférable pour à une procédure de dimensionnement par optimisation de système, qui requiert un modèle rapide et peut accepter beaucoup de contraintes. Cependant, la difficulté principale apparaît lors de la modélisation analytique des structures d’électronique de puissance, notamment celles ayant de la commutation naturelle.Cette thèse propose une approche de modélisation semi-analytique où la résolution des équations implicites est faite par Newton-Raphson ou SQP. Cependant, cette approche pose des difficultés de convergence de la méthode utilisée du point de vue numérique et du point de vue du mode de fonctionnement du convertisseur statique. Ainsi, cette thèse propose différentes alternatives pour les résoudre.En terme d’illustrations, cette thèse s’appuie particulièrement sur des applications avec des redresseurs à diodes qui sont largement utilisés dans les sous-stations de réseaux ferroviaires ou dans les réseaux d’avion,Notamment, un canal de puissance typique d’un Airbus de « nouvelle génération » sert d’application du point de vue de dimensionnement par optimisation. / For the design of static energy conversion systems from power grids, harmonic standards have to berespected. To characterize them, frequency modeling approaches, either numerical or semi-analytical. Thesecond one is more advisable for the sizing by optimization of systems, where a fast model is required and manyconstraints have to be carried out. However, the main difficulties happen in the analytical modeling of powerelectronics structures, especially those with soft commutations.This thesis proposes a semi-analytical modeling approach where the solving of implicit equations iscarried out by Newton-Raphson or SQP. The convergence difficulties are analyzed in two viewpoints:numerically and according the operating mode of the static converters. Then, alternatives are proposed to solvethem.To illustrate the problematic, applications with diode rectifiers (widely used in railway electrical gridsubstations or airline electrical grid) are used. Especially, the sizing of power channel of « new generation» of anAirbus, is made by optimization, using the proposed modelling approach.

Doctor of Philosophy / Civil Engineering / Sunanda Dissanayake / Safe and efficient flow of traffic through work zones must be established by improving work zone conditions. Therefore, identifying the factors associated with the severity and the frequency of work zone crashes is important. According to current statistics from the Federal Highway Administration, 2,372 fatalities were associated with motor vehicle traffic crashes in work zones in the United States during the four years from 2010 to 2013. From 2002 to 2014, an average of 1,612 work zone crashes occurred in Kansas each year, making it a serious concern in Kansas. Objectives of this study were to analyze work zone crash characteristics, identify the factors associated with crash severity and frequency, and to identify recommendations to improve work zone safety. Work zone crashes in Kansas from 2010 to 2013 were used to develop crash severity models. Ordered probit regression was used to model the crash severities for daytime, nighttime, multi-vehicle and single-vehicle work zone crashes and for work zones crashes in general. Based on severity models, drivers from 26 to 65 years of age were associated with high crash severities during daytime work zone crashes and driver age was not found significant in nighttime work zone crashes. Use of safety equipment was related to reduced crash severities regardless of the time of the crash. Negative binomial regression was used to model the work zone crash frequency using work zones functioned in Kansas in 2013 and 2014. According to results, increased average daily traffic (AADT) was related to higher number of work zone crashes and work zones in operation at nighttime were related to reduced number of work zone crashes. Findings of this study were used to provide general countermeasure ideas for improving safety of work zones.

This paper presents a proposed the modeling of power transformers for high-frequency electromagnetic transients. The application of this model allows the evaluation of the windings behavior against the voltage surges imposed by the electric power system. Besides the model, the required calculations to determine the concentrated and distributed parameters which define the representative circuit are detailed. The calculations were performed for a 25 MVA power transformer, using the data obtained from a technical audit between both client and manufacturer, known as design review. The representation of the equipment for the simulation is realized through a descriptive language, known as netlist. The impossibility of measuring the voltage along the power transformer windings subjected to voltage surges has motivated the development of the proposed model and computer simulation. Aiming to evaluate the potentialities of the developed model, the simulations for the power transformer were performed focusing on the determination of the lightning impulse transient voltage distribution along the windings and fully evaluating the obtained results. Alterations of the studied transformer s project were also addressed, considering the windings traditionally used by the manufacturers. A qualitative comparison between the responses of both power transformers is also presented. / Este trabalho apresenta uma proposta de modelagem de um transformador de potência para transitórios eletromagnéticos em altas frequências. O emprego deste modelo possibilita avaliar o comportamento dos enrolamentos frente aos surtos de tensão resultantes de transitórios no sistema elétrico de potência. Além do modelo, são detalhados os cálculos necessários para a determinação dos parâmetros distribuídos e concentrados que definirão o circuito representativo do modelo. Os cálculos foram realizados para um transformador de potência de 25 MVA, a partir dos dados obtidos de uma auditoria técnica entre cliente e fabricante, também conhecida como design review. A representação do modelo do equipamento para a simulação é realizada através de uma linguagem descritiva, netlist. A impossibilidade de medições de tensão ao longo dos enrolamentos do transformador, submetidos a surtos de tensão, motivaram o desenvolvimento do modelo proposto e a sua validação via simulação computacional. Com o objetivo de avaliar as potencialidades do modelo desenvolvido realizaram-se simulações enfatizando a determinação da distribuição das tensões transitórias de impulso atmosférico ao longo dos enrolamentos do transformador, sendo estes resultados avaliados detalhadamente. Também foram abordadas alterações no projeto do transformador estudado, considerando enrolamentos tradicionalmente utilizados pelos fabricantes. É apresentada uma comparação qualitativa entre a resposta do transformador projetado e os estudos de modificação de projeto.

Frequency response analysis (FRA) is a method which is used to detect mechanical faults in transformers. The FRA response of a transformer is determined by its geometry and material properties, and it can be considered as the transformer’s fingerprint. If there are any mechanical changes in the transformer, for example if the windings are moved or distorted, its fingerprint will also be changed so, theoretically, mechanical changes in the transformer can be detected with FRA. The purpose of this thesis is to partly create a simple model for the ferromagnetic material in the transformer core, and partly to investigate the high frequency part of the FRA response of the transformer winding. To be able to realize these goals, two different models are developed separately from each other. The first one is a time- and frequency domain complex permeability model for the ferromagnetic core material, and the second one is a time- and frequency domain winding model based on lumped circuits, in which the discretization is made finer and finer in three steps. Capacitances and inductances in the circuit are calculated with use of analytical expressions derived from approximated geometrical parameters. The developed core material model and winding model are then implemented in MATLAB separately, using state space analysis for the winding model, to simulate the time- and frequency response. The simulations are then compared to measurements to verify the correctness of the models. Measurements were performed on a magnetic material and on a winding, and were compared with obtained results from the models. It was found that the model developed for the core material predicts the behavior of the magnetic field for frequencies higher than 100 Hz, and that the model for the winding predicts the FRA response of the winding for frequencies up to 20 MHz.