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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Buck Converter Design Issues

Rahman, Muhammad Saad January 2007 (has links)
<p>Switch Mode Power Supplies are very important components in present day electronics and have continued to thrive and grow over the past 25 years. This thesis looks inside how the SMPS have evolved over the passage of years with special emphasis to the Synchronous Buck Converter. It also discusses why there is a strong potential to further the study related to designs based around a Synchronous Buck Converter for portable applications. The main objective of the thesis is to look into the controller design for minimizing size, enhancing efficiency and reliability of power converters in portable electronic equipment such as mobile phones and PDAs. The thesis aims to achieve this using a 90 nm process with an input voltage of 1.55V and an output of 1V with a power dissipation of 200mW.</p>
22

Buck Converter Design Issues

Rahman, Muhammad Saad January 2007 (has links)
Switch Mode Power Supplies are very important components in present day electronics and have continued to thrive and grow over the past 25 years. This thesis looks inside how the SMPS have evolved over the passage of years with special emphasis to the Synchronous Buck Converter. It also discusses why there is a strong potential to further the study related to designs based around a Synchronous Buck Converter for portable applications. The main objective of the thesis is to look into the controller design for minimizing size, enhancing efficiency and reliability of power converters in portable electronic equipment such as mobile phones and PDAs. The thesis aims to achieve this using a 90 nm process with an input voltage of 1.55V and an output of 1V with a power dissipation of 200mW.
23

Dynamic Characteristic Analysis for a Static Synchronous Series Compensator Using Intelligent Controllers

Lai, Cheng-ying 03 July 2008 (has links)
The static synchronous series compensator (SSSC) is a series controller of Flexible AC Transmission Systems (FACTS). It can be controlled by Thyristors, it also has the ability of fast control adjustments and high frequency operation. Through impedance compensation, it is able to control the magnitude and directions of the real power flow in the transmission system. In order to achieve a fast and steady response for real power control in power systems, this thesis proposed a unified intelligent controller, which consists of RBFNN and GA for the SSSC to provide better control features for real power control in the dynamic operations of power systems. Finally, the simulation results of the proposed controllers is compared with the conventional proportional plus integral (PI) controllers to demonstrate the superiority and effectiveness of the unified intelligent controller.
24

Decision support algorithms for power system and power electronic design

Heidari, Maziar 10 September 2010 (has links)
The thesis introduces an approach for obtaining higher level decision support information using electromagnetic transient (EMT) simulation programs. In this approach, a suite of higher level driver programs (decision support tools) control the simulator to gain important information about the system being simulated. These tools conduct a sequence of simulation runs, in each of which the study parameters are carefully selected based on the observations of the earlier runs in the sequence. In this research two such tools have been developed in conjunction with the PSCAD/EMTDC electromagnetic transient simulation program. The first tool is an improved optimization algorithm, which is used for automatic optimization of the system parameters to achieve a desired performance. This algorithm improves the capabilities of the previously reported method of optimization-enabled electromagnetic transient simulation by using an enhanced gradient-based optimization algorithm with constraint handling techniques. In addition to allow handling of design problems with more than one objective the thesis proposes to augment the optimization tool with the technique of Pareto optimality. A sequence of optimization runs are conducted to obtain the Pareto frontier, which quantifies the tradeoffs between the design objectives. The frontier can be used by the designer for decision making process. The second tool developed in this research helps the designer to study the effects of uncertainties in a design. By using a similar multiple-run approach this sensitivity analysis tool provides surrogate models of the system, which are simple mathematical functions that represent different aspects of the system performance. These models allow the designer to analyze the effects of uncertainties on system performance without having to conduct any further time-consuming EMT simulations. In this research it has been also proposed to add probabilistic analysis capabilities to the developed sensitivity analysis tool. Since probabilistic analysis of a system using conventional techniques (e.g. Monte-Carlo simulations) normally requires a large number of EMT simulation runs, using surrogate models instead of the actual simulation runs yields significant savings in terms of shortened simulation time. A number of examples have been used throughout the thesis to demonstrate the application and usefulness of the proposed tools.
25

Decision support algorithms for power system and power electronic design

Heidari, Maziar 10 September 2010 (has links)
The thesis introduces an approach for obtaining higher level decision support information using electromagnetic transient (EMT) simulation programs. In this approach, a suite of higher level driver programs (decision support tools) control the simulator to gain important information about the system being simulated. These tools conduct a sequence of simulation runs, in each of which the study parameters are carefully selected based on the observations of the earlier runs in the sequence. In this research two such tools have been developed in conjunction with the PSCAD/EMTDC electromagnetic transient simulation program. The first tool is an improved optimization algorithm, which is used for automatic optimization of the system parameters to achieve a desired performance. This algorithm improves the capabilities of the previously reported method of optimization-enabled electromagnetic transient simulation by using an enhanced gradient-based optimization algorithm with constraint handling techniques. In addition to allow handling of design problems with more than one objective the thesis proposes to augment the optimization tool with the technique of Pareto optimality. A sequence of optimization runs are conducted to obtain the Pareto frontier, which quantifies the tradeoffs between the design objectives. The frontier can be used by the designer for decision making process. The second tool developed in this research helps the designer to study the effects of uncertainties in a design. By using a similar multiple-run approach this sensitivity analysis tool provides surrogate models of the system, which are simple mathematical functions that represent different aspects of the system performance. These models allow the designer to analyze the effects of uncertainties on system performance without having to conduct any further time-consuming EMT simulations. In this research it has been also proposed to add probabilistic analysis capabilities to the developed sensitivity analysis tool. Since probabilistic analysis of a system using conventional techniques (e.g. Monte-Carlo simulations) normally requires a large number of EMT simulation runs, using surrogate models instead of the actual simulation runs yields significant savings in terms of shortened simulation time. A number of examples have been used throughout the thesis to demonstrate the application and usefulness of the proposed tools.
26

Missile Autopilot Design By Projective Control Theory

Doruk, Resat Ozgur 01 January 2003 (has links) (PDF)
In this thesis, autopilots are developed for missiles with moderate dynamics and stationary targets. The aim is to use the designs in real applications. Since the real missile model is nonlinear, a linearization process is required to get use of systematic linear controller design techniques. In the scope of this thesis, the linear quadratic full state feedback approach is applied for developing missile autopilots. However, the limitations of measurement systems on the missiles restrict the availability of all the states required for feedback. Because of this fact, the linear quadratic design will be approximated by the use of projective control theory. This method enables the designer to use preferably static feedback or if necessary a controller plus a low order compensator combination to approximate the full state feedback reference. Autopilots are checked for the validity of linearization, robust stability against aerodynamic, mechanical and measurement uncertainties.
27

Basic Studies on Persistent Current Compensator for Superconducting Magnet by Use of Linear Type Magnetic Flux Pump / リニア型磁束ポンプを適用した超伝導マグネット用永久電流補償装置に関する基礎研究 / リニアガタ ジソク ポンプ オ テキヨウシタ チョウデンドウ マグネットヨウ エイキュウ デンリュウ ホショウ ソウチ ニ カンスル キソ ケンキュウ

Chung, Yoon Do 25 September 2007 (has links)
学位授与大学:京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2864号 ; 請求記号: 新制/工/1421 ; 整理番号: 25549 / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13393号 / 工博第2864号 / 新制||工||1421(附属図書館) / 25549 / UT51-2007-Q794 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 小林 哲生, 准教授 中村 武恒 / 学位規則第4条第1項該当
28

Controle de força de um servoatuador hidráulico através da técnica de linearização por realimentação

Serrano, Miguel Ignácio January 2007 (has links)
Os atuadores hidráulicos são usados em muitas aplicações e áreas de trabalho devido à sua capacidade para manipular grandes forças com baixa inércia, pouca vibração e capacidade de trabalho por longos períodos de tempo. Entretanto, o maior problema no uso destes tipos de atuadores são as características dinâmicas tais como não-linearidade e variação de parâmetros, as quais dificultam seu controle em malha fechada. Assim, para controlar sistemas hidráulicos, é necessário o uso de modelos matemáticos não lineares e a aplicação de leis de controle complexas para obter um seguimento de trajetória com alta precisão. O objetivo principal deste trabalho é a obtenção de um sistema que siga com precisão as trajetórias de referência do tipo senoidais. Para tanto, este trabalho aborda o projeto de uma lei de controle por realimentação de estados (feedback linearization) combinada com o princípio do modelo interno para aplicar no sistema hidráulico de atuação de uma máquina de ensaios de fadiga. O princípio do modelo interno é aplicado utilizando um compensador dinâmico (que contém pólos imaginários com a mesma freqüência que o sinal de referência) num laço externo do sistema linearizado por realimentação de estados. Uma lei de controle do tipo realimentação de estados, considerando os estados do sistema linearizado e os do compensador dinâmico, é projetada para garantir estabilidade no sistema de malha fechada. A fim de avaliar a estratégia de controle proposta são discutidos e apresentados simulações do modelo experimental. / Hydraulic actuators are used in many applications due to their ability in driving large forces with low inertia and little vibration for a long period of time. However, the main problem in controlling these kinds of systems concerns their dynamics, which presents several nonlinearities and parameters variations. Thus, to control hydraulic systems, appropriated nonlinear models and complex control techniques to achieve a stable force regulation with a specified performance are necessary. The purpose of this work is the application of a feedback linearization scheme in the design of a force controller for a hydraulic actuator used in a fatigue test machine. The main control objective considered regards the achievement of sinusoidal force reference tracking. With this aim the internal model principle is applied by using a dynamic compensator (containing imaginary poles with the same frequency of the force reference) in an outer regulation loop. A state feedback control law, considering both the states of the feedback linearized hydraulic system and the ones of the dynamic compensator, is therefore designed in order to stabilize the whole closed-loop system. Experimental model identification and simulation control results are presented and discussed.
29

Controle de força de um servoatuador hidráulico através da técnica de linearização por realimentação

Serrano, Miguel Ignácio January 2007 (has links)
Os atuadores hidráulicos são usados em muitas aplicações e áreas de trabalho devido à sua capacidade para manipular grandes forças com baixa inércia, pouca vibração e capacidade de trabalho por longos períodos de tempo. Entretanto, o maior problema no uso destes tipos de atuadores são as características dinâmicas tais como não-linearidade e variação de parâmetros, as quais dificultam seu controle em malha fechada. Assim, para controlar sistemas hidráulicos, é necessário o uso de modelos matemáticos não lineares e a aplicação de leis de controle complexas para obter um seguimento de trajetória com alta precisão. O objetivo principal deste trabalho é a obtenção de um sistema que siga com precisão as trajetórias de referência do tipo senoidais. Para tanto, este trabalho aborda o projeto de uma lei de controle por realimentação de estados (feedback linearization) combinada com o princípio do modelo interno para aplicar no sistema hidráulico de atuação de uma máquina de ensaios de fadiga. O princípio do modelo interno é aplicado utilizando um compensador dinâmico (que contém pólos imaginários com a mesma freqüência que o sinal de referência) num laço externo do sistema linearizado por realimentação de estados. Uma lei de controle do tipo realimentação de estados, considerando os estados do sistema linearizado e os do compensador dinâmico, é projetada para garantir estabilidade no sistema de malha fechada. A fim de avaliar a estratégia de controle proposta são discutidos e apresentados simulações do modelo experimental. / Hydraulic actuators are used in many applications due to their ability in driving large forces with low inertia and little vibration for a long period of time. However, the main problem in controlling these kinds of systems concerns their dynamics, which presents several nonlinearities and parameters variations. Thus, to control hydraulic systems, appropriated nonlinear models and complex control techniques to achieve a stable force regulation with a specified performance are necessary. The purpose of this work is the application of a feedback linearization scheme in the design of a force controller for a hydraulic actuator used in a fatigue test machine. The main control objective considered regards the achievement of sinusoidal force reference tracking. With this aim the internal model principle is applied by using a dynamic compensator (containing imaginary poles with the same frequency of the force reference) in an outer regulation loop. A state feedback control law, considering both the states of the feedback linearized hydraulic system and the ones of the dynamic compensator, is therefore designed in order to stabilize the whole closed-loop system. Experimental model identification and simulation control results are presented and discussed.
30

Construção e análise de um elipsômetro de compensador girante. / Construction and analysis of a photometric elipsometer with rotating compensator.

Adao Antonio da Silva 23 September 1985 (has links)
Neste trabalho, descreveremos a teoria, a construção e algumas aplicações de um elipsômetro fotométrico de compensador girante e analisador fixo (RCFAE). Além disso, foram feitas medidas dos estados de polarização de um feixe de luz, bem como a medida da constante dielétrica complexa, &#958 = &#9581 - &#9582, de um substrato de ouro, a fim de verificar o desempenho d instrumento. Também foi feita uma análise comparativa da sensibilidade (ou poder de resolução) do elipsômetro construído com a do elipsômetro de analisador girante. Além disso, mostraremos como os resultados das medidas, são independentes da intensidade da luz incidente. / In this work we describe the theory, construction and most important applications of a photometric elipsometer with routing compensator and fixed analyzer. We also analyze the procedures for measuring the polarization states of a light beam and the complex dielectric constant of a substrate of gold, in order to verify the performance of instrument. A comparative analysis of the sensibility (or resolution power) of the elipsometer built with an elipsometer of routing was also made. We show that the results of the measurements are independent of the intensity of the incident light.

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