[pt] Uma bomba centrífuga, depois de concluída a sua instalação, deve vencer uma elevação constante. A variação da rotação vai alterar diretamente a descarga. Como bomba centrífuga é acionada por motor de indução, a variação da freqüência não acarreta variação proporcional na rotação devido a que a nova rotação implica em outro valor da descarga que somente ocorre com torque diferente do anterior e em conseqüência, o deslizamento deve se ajustar para igualar o torque fornecido pelo motor com o novo torque requerido pela bomba. A análise parte dos estudos que relacionam a descarga com a rotação para relacionar a descarga com a freqüência. / [en] Once installation is concluded, a centrifugal pump should withstand constant head. The variation of rotation directly alters the discharge. Since centrifugal pump operates by induction motor, the variation in frequency does not lead to proporcional variation in rotation due to the new rotation being of another discharge value which only occurs with a different torque. Consequently, the sllep should adjust itself to equalize the torque provided by the motor to the new torque required by the pump. The analisis derives from studies which related the discharge to the rotation in order to relate the discharge to the frequency.

[pt] Os motores de indução são as máquinas mais utilizadas nos acionamentos industriais elétricas devido a sua simplicidade, robustez, maior relação torque/corrente, baixa manutenção, etc. Sua aceitação e aplicação em acionamentos com velocidade variável têm sido possível com o desenvolvimento da eletrônica de potência. Atualmente, muitos acionamentos utilizam diversas técnicas para lograr o controle de velocidade por variação da freqüência da rede de alimentação, sendo que o controle vetorial é o mais comum. O presente trabalho, centra-se no estudo do desenvolvimento do motor de indução sob a aplicação do controle de velocidade, através da análise dos parâmetros necessários para realizar o dito controle na faixa de baixa velocidade, sem sensor de velocidade e/ou de posição. O trabalho inicia-se com o estudo das principais características funcionamento do motor de indução. Em seguida, a partir do modelo matemático do motor de indução, são analisados os diferentes tipos de controle de velocidade, com especial ênfase na variação da velocidade através da variação da freqüência. Finalmente, são estudados os parâmetros e métodos para o controle de velocidade sem sensor. O estudo é validado com diversas simulações realizadas no programa MatLab. / [en] The induction motors are the most commonly used eletric motors in the electrical industrial systems due its simplicity, robustness, greater torque/current ratio, low maintenance, etc. its acceptance and applications in operations with variable speed has been possible with the power electronics development. Currently, most of operations use several techniques to achieve the speed control by variable frequency of the power supply with vectorial control being the most common. The present work is centered in the study and development of the induction drive in speed control application, with the analysis of the necessary parameters to control in low speed band, without speed and/or position sensor. The work starts with the study of main functioning characteristic of the motor. After that, from the mathematical model of the induction motor, different speed control techniques are analyzed, with special emphasis in speed variation with variable frequency. Finally, the parameters and methods for sensor less control are studied. The study is variation with several simulations made Matlab program.

[pt] Este trabalho, relacionado com a área de modelagem de cargas para estudos de estabilidade transitória de sistemas elétricos, tem por objetivo discutir a adequação dos modelos clássicos normalmente utilizados, bem como o aprimoramento e desenvolvimento de representações para cargas com características específicas. Inicialmente, são enfocados os aspectos das representações clássicas de cargas e, através de desenvolvimentos teóricos e estudos computacionais, ressaltadas as adequações destas estratégias ao contexto atual. Reconhecendo algumas limitações quanto às técnicas para a obtenção dos parâmetros de motores de indução, apresenta- se procedimentos sistematizados para o tratamento destes componentes de carga. Tendo em vista a busca da melhoria de modelos e respostas aos questionamentos a respeito da relevância da inclusão dos efeitos da variação da freqüência sobre as cargas e parâmetros da rede, o trabalho prossegue com investigações nesta direção. Objetivando a análise do desempenho dos modelos simplificados de cargas através de funções algébricas, são discutidas as propostas atuais e verificadas suas adequações aos estudos de estabilidade. Finalmente, considerando a importância atual das cargas conversoras estáticas, são desenvolvidos modelos apropriados e realizados os estudos necessários à incorporação de unidades retificadoras em programas de estabilidade. / [en] This work, involved with the load modeling for electrical system transiente stability analysis, aim to discuss the classical load models normally used, and to develop and improve representations of specific types of loads. Initially, aspects concerned with classical load representations are dealt with aiming to evaluate, through theoretical and computational analyses, the current employment of such models. Knowing that the techiques to obtain induction motor parameters are still deficient, this work presents some systematic procedures for the treatment of such loads. Additionally, it continues seeking improvements in electrical system component models and answers to the questions about the need for inclusion of the frequency variation effects on loads and network parameters. Moreover, it takes into account the tendencies of using simplified load models represented by algebraic expressions. Some recent proposals in this area are discussed and tested with a view to acess the perfomance of the models in stability studies. Finally, considering the present importance of static load converters, it is developed the related models and presented the necessary studies to include rectifier units in stability programs.

La machine asynchrone est à ce jour la référence dans les moteurs de traction ferroviaire. De nombreuses contraintes dictées par des normes notamment au niveau du bruit acoustique poussent l’industrie à développer des moteurs plus silencieux. Le vrillage connu pour réduire les ondulations de couple semble apporter également une réelle solution afin de diminuer les vibrations et le bruit émis par la machine. C’est dans ce contexte que ce projet en collaboration avec Alstom-Transport situé à Ornans et le soutien de MEDEE (pôle régional sur la maitrise énergétique) est réalisé. Cette thèse se focalise plus particulièrement sur le calcul des forces électromagnétiques dans l’entrefer à l’origine des vibrations, du bruit et du couple. Des modèles analytiques et à éléments finis estimant les forces électromagnétiques et intégrant le vrillage sont présentés et confrontés à des mesures expérimentales de vibration, de bruit et de couple. Les modèles utilisés sont valables pour les machines asynchrones à cage d’écureuil mais sont facilement adaptables pour les machines synchrones. Ils permettent de comprendre l’origine des forces électromagnétiques responsables du bruit et de trouver des configurations de machines moins bruyantes en jouant sur divers paramètres tels que : le vrillage, mais aussi le nombre de paires de pôles, le nombre d’encoches au stator et au rotor, la forme des encoches, la distribution du bobinage, etc. / The induction machine is the reference in railway traction motors. Numerous constraints dictated by standards, particularly regarding acoustic noise, are driving the industry to develop quieter engines. The skewing known to reduce torque ripples seems to also provide a real solution to reduce vibration and noise emitted by the machine. In this context, the project is realized in collaboration with Alstom-Transport located in Ornans with the support of MEDEE (regional pole on energy control). This thesis focuses on the calculation of magnetic forces in the air gap which originate vibration, noise and torque. Analytical and finite element models, which estimate electromagnetic forces and integrate skewing, are presented and compared with experimental measurements of vibration, noise and torque. The models used are valid for the squirrel-cage induction machines but are easily adaptable for synchronous machines. This allows one to understand the origin of the electromagnetic forces responsible for the noise, and to find configurations of less noisy machines. Various parameters such as skewing can be modified to reach this goal, as well as the number of pole pairs, the stator and rotor teeth number, the slot shape, the winding distribution, and so on.

No description available.

Tradicionalmente, la detección de faltas en máquinas eléctricas se basa en el uso de la Transformada Rápida de Fourier ya que la mayoría de las faltas pueden ser diagnosticadas con ella con seguridad si las máquinas operan en condiciones de régimen estacionario durante un intervalo de tiempo razonable. Sin embargo, para aplicaciones en las que las máquinas operan en condiciones de carga y velocidad fluctuantes (condiciones no estacionarias) como por ejemplo los aerogeneradores, el uso de la Transformada Rápida de Fourier debe ser reemplazado por otras técnicas. La presente tesis desarrolla una nueva metodología para el diagnóstico de máquinas de inducción de rotor de jaula y rotor bobinado operando en condiciones no estacionarias, basada en el análisis de las componentes de falta de las corrientes en el plano deslizamiento frecuencia. La técnica es aplicada al diagnóstico de asimetrías estatóricas, rotóricas y también para la falta de excentricidad mixta. El diagnóstico de las máquinas eléctricas en el dominio deslizamiento-frecuencia confiere un carácter universal a la metodología ya que puede diagnosticar máquinas eléctricas independientemente de sus características, del modo en el que la velocidad de la máquina varía y de su modo de funcionamiento (motor o generador). El desarrollo de la metodología conlleva las siguientes etapas: (i) Caracterización de las evoluciones de las componentes de falta de asimetría estatórica, rotórica y excentricidad mixta para las máquinas de inducción de rotores de jaula y bobinados en función de la velocidad (deslizamiento) y la frecuencia de alimentación de la red a la que está conectada la máquina. (ii) Debido a la importancia del procesado de la señal, se realiza una introducción a los conceptos básicos del procesado de señal antes de centrarse en las técnicas actuales de procesado de señal para el diagnóstico de máquinas eléctricas. (iii) La extracción de las componentes de falta se lleva a cabo a través de tres técnicas de filtrado diferentes: filtros basados en la Transformada Discreta Wavelet, en la Transformada Wavelet Packet y con una nueva técnica de filtrado propuesta en esta tesis, el Filtrado Espectral. Las dos primeras técnicas de filtrado extraen las componentes de falta en el dominio del tiempo mientras que la nueva técnica de filtrado realiza la extracción en el dominio de la frecuencia. (iv) La extracción de las componentes de falta, en algunos casos, conlleva el desplazamiento de la frecuencia de las componentes de falta. El desplazamiento de la frecuencia se realiza a través de dos técnicas: el Teorema del Desplazamiento de la Frecuencia y la Transformada Hilbert. (v) A diferencia de otras técnicas ya desarrolladas, la metodología propuesta no se basa exclusivamente en el cálculo de la energía de la componente de falta sino que también estudia la evolución de la frecuencia instantánea de ellas, calculándola a través de dos técnicas diferentes (la Transformada Hilbert y el operador Teager-Kaiser), frente al deslizamiento. La representación de la frecuencia instantánea frente al deslizamiento elimina la posibilidad de diagnósticos falsos positivos mejorando la precisión y la calidad del diagnóstico. Además, la representación de la frecuencia instantánea frente al deslizamiento permite realizar diagnósticos cualitativos que son rápidos y requieren bajos requisitos computacionales. (vi) Finalmente, debido a la importancia de la automatización de los procesos industriales y para evitar la posible divergencia presente en el diagnóstico cualitativo, tres parámetros objetivos de diagnóstico son desarrollados: el parámetro de la energía, el coeficiente de similitud y los parámetros de regresión. El parámetro de la energía cuantifica la severidad de la falta según su valor y es calculado en el dominio del tiempo y en el dominio de la frecuencia (consecuencia de la extracción de las componentes de falta en el dominio de la frecuencia). El coeficiente de similitud y los parámetros de regresión son parámetros objetivos que permiten descartar diagnósticos falsos positivos aumentando la robustez de la metodología propuesta. La metodología de diagnóstico propuesta se valida experimentalmente para las faltas de asimetría estatórica y rotórica y para el fallo de excentricidad mixta en máquinas de inducción de rotor de jaula y rotor bobinado alimentadas desde la red eléctrica y desde convertidores de frecuencia en condiciones no estacionarias estocásticas. / Vedreño Santos, FJ. (2013). Diagnosis of electric induction machines in non-stationary regimes working in randomly changing conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34177 / TESIS

The objective of the dissertation is to develop simplified analytical models for typical linear-motion and rotary-motion energy-conversion systems under active DC excitation without tedious numerical-simulation effort, and provide practical implementation of the models in optimal-design and thermal-protection aspects. The model of a vacuum automatic circuit recloser (a typical linear-motion system under DC excitation) is first developed in the form of a non-linear discontinuous eighth-order dynamic system. The model is then used to simulate the transient mechanical and electromagnetic performance during the opening and closing movements of the recloser. Such a model is not found in the literature. Although the model is based on certain simplifying assumptions, the result is validated by high-speed-camera measurements. In addition, the impact of key design variables is explored, based on which an improved recloser design is proposed, and helps to optimize capital and production costs without degrading performance. Further analytical investigation is carried out in modeling an inverter-fed induction motor (IM) (a typical rotary-motion system) with active DC injection. The IM is closed-loop controlled via two popular motor-control algorithms, namely, the direct-torque-control (DTC) algorithm and field-oriented-control (FOC) algorithm. Quantitative relationships between the changes of various machine variables during the active DC excitation are provided in the theoretical analysis. The developed DC-injection model is further simplified for practical implementation. The developed IM model under DC injection results in practical ways to excite a proper amount of DC current directly or indirectly into IM stator windings via different closed-loop motor-control algorithms. In a DTC motor-drive system, the modeling work makes it possible to excite the DC current indirectly inside the motor by superimposing a stator-flux-linkage-bias command in the flux-control loop or a torque-ripple command in the torque-control loop. The proposed flux-linkage-injection and torque-injection methods are the first novel efforts to implement the DC-signal-injection method in a DTC motor-drive system. In addition, the analysis carried out in a standard FOC drive system brings about an improved DC-current-injection approach: the torque ripple in this method is significantly mitigated compared to all existing DC-injection methods in FOC systems. The proposed DC-injection methods, either in a DTC or an FOC system, lead to a simple, low-cost, accurate, and non-invasive thermal-monitoring scheme for closed-loop-controlled IMs, where the stator temperature is indirectly estimated from stator resistance. Furthermore, considering inverter non-idealities, there is a challenge for a typical inverter drive to accurately estimate the DC component of motor terminal voltages. The existing methods are extended to provide a complete study of the real-time signal-processing technique for both DTC and FOC algorithms, and are finally implemented in a custom-built programmable motor-drive system. The experimental results demonstrate that the proposed technique gives accurate and robust stator-temperature estimation, regardless of the operating conditions and cooling modes. The analytical modeling method for the linear-motion and rotary-motion energy-conversion systems can be further extended to other power devices with similar mechanisms, and implemented in optimal design, control, and thermal-protection areas.

This thesis deals with thermal management aspects of electric machinery used in high-performance  applications  with  particular  focus put  on electric machines designed for hybrid electric vehicle applications. In the first part of this thesis,  new thermal models of liquid (water and oil) cooled electric machines are proposed.  The proposed thermal models are based on a combination of lumped parameter (LP)  and numerical methods. As  a first  case study,  a permanent-magnet  assisted  synchronous reluctance machine (PMaSRM) equipped with a housing water jacket is considered.  Particular focus is put on the stator winding and a thermal model is proposed that divides the stator slot into a number of elliptical copper and impregna- tion layers.  Additionally, an analysis, using results from a proposed simplified thermal finite element (FE)  model representing only a single slot of the sta- tor and its corresponding end winding, is presented in which the number of layers and the proper connection between the parts of the LP thermal model representing the end winding and the active part of winding are determined. The approach is attractive due to its simplicity  and the fact  that it closely models the actual temperature distribution for common slot geometries.  An oil-cooled induction machine where the oil is in direct contact with the stator laminations  is also considered.  Here, a multi-segment structure is proposed that  divides  the  stator,  winding and cooling  system  into  a number  of an- gular  segments.   Thereby,  the  circumferential  temperature  variation  due to the  nonuniform distribution  of the  coolant  in the  cooling  channels  can be predicted. In the  second part  of this  thesis,  the  thermal  impact  of using  different winding impregnation  and steel  lamination  materials  is  studied.   Conven- tional varnish, epoxy and a silicone based thermally conductive impregnation material are investigated and the resulting temperature distributions in three small induction machines are compared. The thermal impact of using different steel lamination materials is investigated by simulations using the developed thermal  model  of the water  cooled  PMaSRM. The  differences  in alloy con- tents and steel lamination thickness are studied separately and a comparison between the produced iron losses and the resulting hot-spot temperatures is presented. Finally, FE-based approaches  for  estimating  the  induced  magnet  eddycurrent losses in the rotor of the considered PMaSRM are reviewed and compared in the  form  of a case  study  based on simulations.   A  simplified three-dimensional  FE model  and an analytical  model,  both  combined  with time-domain 2D FE analysis, are shown to predict the induced eddy current losses with a relatively good accuracy compared to a complete 3D FE based model.  Hence, the two simplified approaches are promising which motivates a possible future experimental verification. / <p>QC 20130528</p>

This thesis presents a study of inter-bar current effects on induction motors with die-cast aluminium and die-cast copper rotors. The parasitic effects introduced by these currents are analyzed and possible solutions to these problems are presented. This is realized by developing analytical tools for the simulation of inter-bar current effects. The methods used are verified by measurements on prototype machines. It is shown that the inter-bar currents can have a considerable effect on the motor starting performance, which can result in a reduced pull-out torque. At rated operation, this is seen as increased harmonic rotor currents, having a negative effect on the motor performance. Results from calorimetric measurements show, that the efficiency gained when substituting a skewed die-cast aluminium rotor with a skewed die-cast copper rotor, is less than the theoretical expectation. It is shown that this is a result of a reduced power factor for the copper rotor. High inter-bar currents are believed to be the origin of this effect, increasing the harmonic content in the rotor magnetomotive force. This would be seen as an increased rotor leakage reactance. Results from locked-rotor tests, and simulations using measured values of inter-bar resistance, support this theory. It is shown, that these negative effects are suppressed to a negligible level by the use of an unskewed rotor, but to the expense of a large synchronous torque at a low speed. By using a modulated rotor concept, having an asymmetrical rotor slot distribution, an unskewed rotor is designed to reduce this parasitic torque. Measurements on a prototype machine show that the modulated rotor suppresses both the inter-bar currents and the synchronous torque, resulting in an improved starting performance, without any significant change of the motor efficiency. The presented results strengthen the potential of the modulated rotor concept, introducing new possibilities for the reduction of negative effects appearing in induction machines. / <p>QC 20130320</p>

Made available in DSpace on 2016-08-17T14:52:53Z (GMT). No. of bitstreams: 1 Marcelino Pacelli Macedo Muniz.pdf: 1319254 bytes, checksum: c1a5a0a8a6639aaf2e332ea2b50a920d (MD5) Previous issue date: 2004-08-27 / In this work the results of the simulations of the model of the machine are compared with real curves to get the validation of the model, demonstrating a possible application of the model. / Neste trabalho os resultados das simulações do modelo da máquina são comparados com curvas reais para se obter a validação do modelo, demonstrando uma possível aplicação do modelo.