Single phase switched reluctance machines (SRMs) have a special place in the emerging high-volume, low-cost and low-performance applications in appliances and also in high-speed low-power motor drives in various industrial applications. Single phase SRMs have a number of drawbacks: low power density as they have only 50% utilization of windings, lack of self-starting feature unless otherwise built in to the machine, most of the times with permanent magnets or sometimes with distinct and special machine rotor configurations or additional mechanisms. Many of these approaches are expensive or make the manufacturing process more difficult. In order to overcome such disadvantages a method involving interpoles and windings is discussed in this research. Also, a new and novel converter topology requiring only a single switch and a single diode is realized. This research tests the concepts and feasibility of this new single-phase SRM motor topology and converter in one quadrant operation. The converter electronics and a simple minimum component, minimum cost analog converter are designed and implemented. The entire system is simulated and evaluated on its advantages and disadvantages. Simple testing without load is performed. This system has a large number of possibilities for development. Due to its lightweight, compact design and efficient, variable high-speed operation, the system might find many applications in pumps, fans, and drills. / Master of Science

The electromagnetic behavior of magnetic devices used in power electronics circuitry, is studied in order to predict their performance within a context of desirable circuit parameters. Past efforts have focused on simplifications widely used in electric machinery applications. Due to the greatly increased operating frequencies of today's circuits (in the upper kHz and lower MHz region), the operation and design of magnetic components greatly differs from those of 60 Hz machinery. A set of models based on assumptions that are unique to the these devices used in power electronics are put forth. The entire approach is based on deriving models from solutions of the field equations, rather than using older, less accurate circuit analogies. More importantly, models are needed for accurate design and optimization processes of complete power electronic systems, in which the magnetic components form a small part. Solutions are sought without using the popular simplifications at very low and very high frequencies, since they are not accurate at intermediate frequencies encountered in power electronics. The conductors used in transformers and inductors are modelled in these high frequency regions. / Ph. D.

No description available.

Within the framework of this thesis, the electron beam melting of pure copper for the purpose of producing electrical windings was examined. The conventional manufacturing process of copper windings was investigated, and the potential advantages offered by the design freedom inherent in the electron beam melting process were explored. A comprehensive parameter study was conducted to optimize the existing production parameters for the electron beam melting of pure copper, with a specific focus on achieving the desired material properties suitable for electric motor windings. Moreover, according to additive manufacturing possibilities, conceptual winding models were developed and subsequently were fabricated in a laboratory setting using electron beam melting. The investigation revealed a notable correlation between the achievable wall thickness and the focus offset. A focused electron beam, which was achieved with a focus offset of 17 mA, allowed for the production of thinner walls with reduced surface roughness. Additionally, the study highlighted that the density of the manufactured parts decreased as the hatch offset increased, particularly posing a more critical impact on smaller cross-sectional areas than larger ones. Furthermore, implementing a double-scanned contour for the hatch contributed to diminishing roughness while simultaneously increasing the maximum density to 99.6 %. Influencing the electrical conductivity of printed copper samples through heat treatment was successfully demonstrated, resulting in a conductivity of 91.7% ± 1.8% IACS post-heat treatment. / Inom ramen för denna avhandling undersöktes elektronstrålesmältningen av ren koppar i syfte att producera elektriska lindningar. Den konventionella tillverkningsprocessen av kopparlindningar undersöktes, och de potentiella fördelarna som erbjuds av designfriheten som är inneboende i elektronstrålesmältningsprocessen undersöktes. En omfattande parameterstudie genomfördes för att optimera befintliga produktionsparametrar för elektronstrålesmältning av ren koppar, med särskilt fokus på att uppnå önskade materialegenskaper lämpliga för elmotorlindningar. Dessutom, i enlighet med additiva tillverkningsmöjligheter, utvecklades konceptuella lindningsmodeller och tillverkades därefter i laboratoriemiljö med användning av elektronstrålesmältning. Undersökningen avslöjade en anmärkningsvärd korrelation mellan den möjliga väggtjockleken och fokusförskjutningen. En fokuserad elektronstråle, som uppnåddes med en fokusförskjutning på 17 mA, möjliggjorde produktion av tunnare väggar med minskad ytjämnhet. Dessutom visade studien att densiteten hos de tillverkade delarna minskade när avståndet mellan smältlinjerna ökade, vilket i synnerhet innebar en mer kritisk påverkan på mindre tvärsnittsareor än större. Dessutom bidrog implementeringen av en dubbelskannad kontur för luckan till att minska grovheten samtidigt som den maximala densiteten ökade till 99,6 %. Att påverka den elektriska ledningsförmågan hos tryckta kopparprover genom värmebehandling demonstrerades framgångsrikt, vilket resulterade i en ledningsförmåga på 91,7 % ± 1,8 % IACS efter värmebehandling.

The advent and proliferation of planar technologies for power converters are driven in part by the overall trends in analog and digital electronics. These trends coupled with the demands for increasingly higher power quality and tighter regulations raise various design challenges. Because inductors and transformers constitute a rather large part of the overall converter volume, size and performance improvement of these structures can subsequently enhance the capability of power converters to meet these application-driven demands. Increasing the switching frequency has been the traditional approach in reducing converter size and improving performance. However, the increase in switching frequency leads to increased power loss density in windings and core, with subsequent increase in device temperature, parasitics and electromagnetic radiation. An accurate set of reduced-order modeling methodologies is presented in this work in order to predict the high-frequency behavior of inductors and transformers. Analytical frequency-dependent expressions to predict losses in planar, foil windings and cores are given. The losses in the core and windings raise the temperature of the structure. In order to ensure temperature limitation of the structure is not exceeded, 1-D thermal modeling is undertaken. Based on the losses and temperature limitation, a methodology to optimize performance of magnetics is outlined. Both numerical and analytical means are employed in the extraction of transformer parasitics and cross-coupling. The results are compared against experimental measurements and are found to be in good accord. A simple near-field electromagnetic shield design is presented in order to mitigate the amount of radiation. Due to inadequacy of existing winding technology in forming suitable planar windings for PCB application, an alternate winding scheme is proposed which relies on depositing windings directly onto the core. / Master of Science

L’émergence du concept d’un avion plus électrique implique une refonte en profondeur des réseaux embarqués. L’axe principalement développé repose sur une augmentation de la tension du réseau et un passage au bus continu. Le contrôle des actionneurs électriques embarqués passe alors par l’utilisation massive de convertisseurs électroniques qui vont imposer des fronts de tension très raides et des contraintes particulières aux enroulements des machines. Les oscillations pseudopériodiques qui suivent ces fronts raides sont à l’origine de champs électriques intenses qui peuvent dépasser le seuil d’apparition des décharges partielles (PDIV) et de ce fait provoquer une dégradation rapide des isolants classiques qui sont à base de polymères. Le travail effectué dans cette thèse est centré sur l’étude d’une nouvelle méthode de conception des bobinages permettant la réduction des problèmes de décharges partielles. Un dispositif expérimental mis au point dans ce cadre reproduit les contraintes imposées par des convertisseurs modernes et permet de mesurer les tensions inter-spires d’une bobine. L’étude expérimentale met en évidence les phénomènes àprendre en compte avec ce type d’alimentation et donne une première idée des axes d’optimisation envisageables. Un modèle prédictif capable de donner la distribution des tensions inter-spires, en réponse à un front raide de tension, aide à identifier les points critiques. Les paramètres constitutifs de ce modèle ont été déterminés en utilisant des méthodes analytiques, expérimentales et numériques. Compte tenu de la complexité du modèle, un outil numérique automatisé a été élaboré afin de simuler le modèle des bobines étudiées. Plusieurs types de bobinage ont été analysés et optimisés avec succès. Cette optimisation consiste à diminuer la tension inter-spires en agissant sur l’arrangement des fils dans les encoches. L’utilisation des bobines optimisées avec cette méthode permet d’envisager une nette amélioration de la fiabilité des machines électriques. / The emergence of the concept of a more electric aircraft requires a major overhaul of onboard grid. The main developed axis is based on an increase in the grid voltage and a switch to DC bus. In this context, the onboard electric actuators are supplied through power electronic converters that will impose very fast voltage fronts and particular constraints in the windings of the machines. The transient over-voltages that follow the steep-fronted pulses are the source of intense electric fields which may exceed the partial discharge inception voltage (PDIV) and cause a rapid deterioration of polymer based insulators. This thesis focuses on the study of a new design method of the windings in order to reduce problems of partial discharges. An experimental device developed in this framework reproduces the constraints of modern converters and allows measuring the turn-to-turn voltages of a coil. The experimental study shows the phenomena to be considered with this type of power supply and gives an idea of possible areas for optimization. A predictive model able to give the distribution of turn-to-turn voltages, in response to a steep-fronted voltage, helps to identify critical points. The constitutive parameters of this model were determined using analytical, experimental and numerical methods. Given the complexity of the model, an automated numerical tool has been developed in order to simulate the model of studied coils. Several types of coil have been analyzed and optimized successfully. This optimization consists in reducing the turn-to-turn voltages by acting on the arrangement of the wires in the slots. The use of optimized coils with this method allows envisaging a significantimprovement in the reliability of electrical machines.

Submitted by Gustavo Nascimento (gustavo.diniz@ufcg.edu.br) on 2018-02-06T14:28:39Z No. of bitstreams: 1 EDUARDO JORGE CALHEIROS JUNIOR - DISSERTACAO PPGEE 2014.pdf: 3431884 bytes, checksum: 5d6e954510b9e7405666b81ef4f13f30 (MD5) / Made available in DSpace on 2018-02-06T14:28:39Z (GMT). No. of bitstreams: 1 EDUARDO JORGE CALHEIROS JUNIOR - DISSERTACAO PPGEE 2014.pdf: 3431884 bytes, checksum: 5d6e954510b9e7405666b81ef4f13f30 (MD5) Previous issue date: 2014-06 / As análises de adequabilidade de equipamentos são indispensáveis para permitir que as empresas do setor elétrico conheçam as condições em que os mesmos operam, garantindo assim o desempenho dos ativos da empresa e sua disponibilidade no Sistema Interligado Nacional. Dentre os equipamentos analisados, destacam-se os transformadores de potência pelo seu alto custo e a sua importância para o sistema elétrico. Grande parte das falhas em transformadores de potência é de origem dielétrica, relacionadas com a danificação da isolação dos condutores devido às deformações mecânicas ocasionadas pelas altas correntes de curto-circuito passantes nos enrolamentos, reduzindo a vida útil do equipamento. A partir destas considerações, propôs-se avaliar os esforços eletromecânicos internos a alguns transformadores de potência presentes no sistema CHESF, por intermédio de simulações computacionais, quando da ocorrência de curto-circuito trifásico. A metodologia para as simulações consistiu em selecionar os transformadores a serem analisados e coletar as informações técnicas necessárias fornecidas pelos fabricantes. Posteriormente foram determinadas as condições sistêmicas às quais os transformadores estariam submetidos e obtidos os níveis de curto-circuito resultantes, para então efetuar as simulações propriamente ditas. Os resultados das simulações computacionais mostraram os esforços eletromecânicos estimados em quatro transformadores de potência em operação no sistema elétrico da CHESF, resultantes do efeito dinâmico da corrente de curto-circuito trifásico que percorrem os enrolamentos do transformador, considerando diferentes configurações sistêmicas. As conclusões das análises dos resultados indicaram possíveis casos de superações de limites admissíveis e revelou a importância dos aspectos construtivos dos transformadores na sua capacidade de suportar os esforços mecânicos causados por curtos-circuitos. / Analysis of suitability of equipment are indispensable for the electric sector companies meet the conditions in which they operate, thus ensuring the performance of the company's assets and its availability in the National Interconnected System (Sistema Interligado Nacional). The power transformers are included among the analyzed equipment due to its high cost and importance for the electrical system. Most faults in power transformers is of dielectric origin, related to insulation damage due to mechanical deformations, caused by the high short-circuit currents in the windings, reducing the life of the equipment. Then, it was proposed to evaluate the internal electromechanical efforts to some power transformers present in the CHESF system, through computer simulations, in the event of a three-phase short circuit. The methodology for the simulations consisted to select the transformers to parse and collect the necessary technical information provided by the manufacturers. Later, certain systemic conditions in which the transformers would be subjected were defined, it was obtained the resulting short circuit levels and then was performed the simulations themselves. The results of the computer simulations showed the electromechanical efforts estimated at four power transformers in operation in the CHESF electrical system, resulting from the dynamic effect of three-phase short-circuit current that run through the windings of the transformer, considering different systemic configurations. The conclusions of the analysis results indicated possible cases of overruns of permissible limits and reveal the importance of the transformers constructive aspects in their ability to withstand the mechanical stress caused by short circuits.

Orientador: Edson Bim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-07-21T11:58:56Z (GMT). No. of bitstreams: 1 Pereira_ValmirMachado_M.pdf: 3590571 bytes, checksum: 64d5729c458a96919ef78024257af6a4 (MD5) Previous issue date: 1996 / Resumo: Esta dissertação tem o objetivo de determinar um modelo matemático para o motor de indução bifásico assimétrico com os enrolamentos de estator conectados em T e investigar algumas propriedades tais como aceleração livre, característica estática conjugado-velocidade e as correntes em regime permanente. Este motor é projetado para ser alimentado a partir de duas fases e do neutro, e requer um valor particular para a relação de espiras entre os enrolamentos do estator. Inicialmente, uma transformação de variáveis é realizada com a finalidade de encontrar um motor equivalente que não possua nenhum ponto condutivo comum entre os enrolamentos e que apresente a mesma fm.m do motor original. Fazendo uso do conceito de circuitos acoplados são obtidas as equações básicas. A seguir, essas variáveis são escritas no sistema de referência estacionário e um circuito equivalente é obtido. Utilizando esse circuito equivalente, são apresentados resultados de simulação computacional e resultados de testes experimentais.A comparação dos mesmos exibiram uma boa concordância,mostrando que o modelo matemático é adequado / Abstract: This dissertation has the aim of determining a mathematical model for asymmetrical two-phase induction motor with T-connected stator windings and to investigate some properties such as free acceleration, steady-state torque-speed characteristic and steady-state currents. This motor is designed to operate from supply of two phases and neutral, and a particular value for the stator tums ratio is required. First, a transformation of variables is accomplishedto obtain an equivalent motor that do not have electric connection and that presents the same m.m.f. of original motor. Making use of the concept couple circuits, the basic equations are derived. Second, these variables are written in the stationary referencefTameand an equivalentcircuit is obtained. By using this equivalent circuit, computer simulationis presented and compared with experimental results. The tests exhibited a good agreement, showing that the mathematical model is adequate / Mestrado / Mestre em Engenharia Elétrica

Frequency response analysis (FRA) of transformers is universally accepted as a highly sensitive tool to detect deformations in its windings. This is evident from the fact that customized commercial equipment (popularly called FRA or SFRA instruments) are used and recently the IEEE has issued a draft trial-use guide. Nevertheless, use of FRA is still limited to only detection and there is little progress towards its use for localization of winding deformation. Toward this end, a possible approach would be to compare the healthy and deformed systems in a suitable domain, e.g., their respective models could be compared. In this context, the mutually-coupled ladder network is ideally suited because not only does it map the length of the winding to sections of the ladder network, but, also inherently captures all subtle intricacies of winding behaviour under lightning impulse excitations insofar as the terminal response, internal oscillations and voltage distributions are concerned. The task of constructing a ladder network from frequency response is not trivial, and so exploration of newer methods is imperative. A system can comprehensively be characterized by its frequency response. With this as the starting point, many approaches exist to construct the corresponding rational function (in s-domain). But, the subsequent step of converting this rational function into a physically-realizable mutually-coupled ladder network has, as yet, remained elusive. A critical analysis of the circuit synthesis literature reveals that there exists no analytical procedure to achieve this task, a fact unequivocally stated by Guillemin in his seminal book "Synthesis of Passive Networks". In recent years, use of iterative methods to synthesize such ladder networks has also been attempted with some degree of success. However, there exists a lot of scope for improvement. Based on this summary, the objectives of this thesis are as follows- _ Development of an analytical procedure, if possible, to synthesize a mutually-coupled ladder network starting from the s-domain representation of the frequency response _ Construction of a nearly-unique, mutually-coupled ladder network employing constrained optimization technique and using frequency response as input, with time-efficiency, physical realizability and repeatability as its features In Chapter 2, analytical solution is presented to convert a given driving-point impedance function (in s-domain) into a physically-realizable ladder network with inductive couplings (between any two sections) and losses considered. The number of sections in the ladder network can vary, but, its topology is assumed fixed. A study of the coefficients of the numerator and denominator polynomials of the driving-point impedance function of the ladder network, for increasing number of sections, led to the identification of certain coefficients, which exhibit very special properties. Generalized expressions for these specific coefficients have also been derived. Exploiting their properties, it is demonstrated that the synthesis method essentially turns out to be an exercise of solving a set of linear, simultaneous, algebraic equations, whose solution directly yields the ladder network elements. The proposed solution is novel, simple, and guarantees a unique network. Presently, the formulation can synthesize a unique ladder network up to 6-sections. Although it is an analytical solution, there are issues which prevent its implementation with actual FRA data. Keeping the above aspect in mind, the second part of the thesis presents results of employing an artificial bee colony search algorithm for synthesizing a mutuallycoupled lumped-parameter ladder network representation of a transformer winding, starting from its measured magnitude frequency response. The bee colony algorithm is modified by defining constraints and bounds to restrict the search-space and thus ensure synthesis of a nearly-unique ladder network, corresponding to each frequency response. Ensuring near-uniqueness while constructing the reference circuit (i.e., a uniform healthy winding) is the objective. The proposed method is easy to implement, time-efficient, ensures physical realizability and problem associated with supply of initial guess in existing methods is circumvented. Experiments were performed on two types of actual, single, isolated transformer windings (continuous-disc and interleaveddisc) and the results are encouraging. Further details are presented in the thesis.

This master thesis focuses on the estimation of losses in windings of a high-speed PermanentMagnet (PM) motor. The PM motor studied in this thesis is applied to a nut-runner systemwith specic characteristics such as operating at a high speed (30000 rpm), relatively smallsize and being slot-less. Previously published analytical models for calculation the losses inwindings are discussed in the literature study along with related background theory. Finiteelement method (FEM) 2D is applied in the simulations using FLUX v12. Simulations beginwith several conductors and bundles. Meanwhile, the analytical estimation of those caseswas carried out. The comparisons between results from both sources are discussed. Beforefurther investigations, the way of connection of bundles and conductors and the applicationof symmetrical conditions for following simulations are discussed. Furthermore, the wholewindings with a iron ring and the rotor are simulated step by step in FLUX. Eect of ironmaterial, lamination thickness and base value are investigated. Finally, losses in windingswith various situations are calculated and compared at 10 kHz and 20 kHz. / Detta examensarbete behandlar uppskattning av forluster i lindningarna hos en permanentmagnet(PM) hoghastighets-motor. PM-motorn som studerats i denna avhandling tillhor ettmutterdragarsystem avsett for industriellt bruk. Utmarkande egenskaper for denna ar hoghastighet (30000 rpm), relativt liten storlek och avsaknad av statorspar. Tidigare publiceradeanalysmodeller for forlustberakningar i lindningar diskuteras i litteraturstudien tillsammansmed tillhorande bakgrundsteori. Finita Element Metoden (FEM) 2D anvands i simuleringarna.FEM-studierna har utforts i FLUX v12. Studierna utfors initialt pa era ledareoch buntar parallellt med analytiska uppskattningar for dessa. Resultaten fran bada kallornajamfors och diskuteras. Vidare diskuteras olika mojligheter till anslutning av era ledare ochledarvarv, samt tillampning av symmetriska villkor for vidare simuleringar. Lindningarnasimuleras darefter stegvis tillsammans med en jarnring och rotor. Paverkan av jarnmaterial,laminat-tjocklek och basvarde utreds. Slutligen utfors forlustjamforelser i lindningarna forolika kongurationer vid 10 kHz och 20 kHz. / Buntade, ledare, FEM 2D, forluster, PM motor, yteekt och narhetseekt, vridna, lindningarna