• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 7
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 13
  • 13
  • 7
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Konceptstudie av universell testrigg för växellådor / Concept study of a universal test rig for gearboxes

Dahl, Anders, Svensson, Johan January 2016 (has links)
Det här examensarbetet skildrar en konceptstudie och kostnadsuppskattning av enuniversell testrigg för växellådor. Arbetet har genomförts på uppdrag av SwepartTransmission AB och har resulterat i koncept- och komponentförslag samtkostnadsuppskattning av ett universellt test system av växellådor. / This degree project cover a concept study and cost analyses of a universal test rig forgears. The project has been performed for Swepart Transmission AB and has resultedin a concept and component suggestion as well as cost analysis of a universal testsystem for gears.
2

Eine vergleichende Betrachtung ausgewählter energieoptimaler Regelungsstrategien von Asynchronmaschinen

Tannenbring, Jonas, Kertzscher, Jana 21 September 2021 (has links)
Der vorliegende Beitrag soll einen bewertenden Überblick über ausgewählte energieoptimale Regelungsstrategien für Asynchronmaschinen (ASM) geben . Diese werden zunächst in einer Simulationsumgebung implementiert und parametrisiert. Es erfolgt die Untersuchung beim Abfahren eines Fahrzyklus, sowie an einzelnen Lastpunkten. Die Resultate werden anhand ihrer Robustheit, der Praktikabilität des Regelverfahrens und nicht zuletzt am Energiesparpotential bewertet. Im ersten Teil wird die Struktur sowie Modellierung der zum Test der Regelungsalgorithmen verwendeten Komponenten vorgestellt. Auch werden die Regelungsstrategien an sich in Struktur und Funktion näher beleuchtet. Die Parametrisierung der entsprechenden Modelle erfolgt aus realen Prüfstandsdaten. Im zweiten Teil wird näher auf die zur späteren Bewertung verwendeten Verlustleistungsberechnung eingegangen. Der dritte Teil beschäftigt sich mit der Darstellung des zur Simulation verwendeten Lastzyklus. Zuletzt werden die Ergebnisse der Simulation vorgestellt und bewertet. / The present article is intended to provide an evaluative overview of four selected energy-optimized control strategies for asynchronous machines (ASM). These are first implemented and parameterized in a simulation environment. The investigation is carried out when running a driving cycle and at individual load points. The results are assessed on the basis of their robustness, practicability and, last but not least, their energy saving potential. In the first part, the structure and modeling of the components used to test the control algorithms is presented. The control strategies themselves are also examined in more detail in terms of structure and function. The corresponding models are parameterized from real test bench data. The second part deals in more detail with the power loss calculation used for the subsequent evaluation. The third deals with the representation of the load cycle used for the simulation. Finally, the results of the simulation are presented and evaluated.
3

Výpočet průběhu chladicího média v asynchronním motoru / Calculation of the cooling medium in the asynchronous

Trnka, Zbyněk January 2011 (has links)
The aim of this master´s thesis was to model the fan for the induction motor, and then to solve this model using Ansys CFX in the terms of flow, when considering the different speeds of rotation of the rotor. The introduction of this work is dedicated to basic terms and definitions from spheres of fluid flow, cooling of the electrical machines, especially to the cooling of the asynchronous machine. There is also attention paid to losses in this machine. Finally, there is modeled radial fan and an air gap of specified induction machine. By using Ansys CFX the flow, which passes from the fan into the air gap, is analyzed.
4

Diagnostika točivých elektrických strojů / Diagnostics of rotating electric machines

Soukup, Patrik January 2018 (has links)
The thesis Diagnostics of rotating electric machines deals with the theory of diagnostics of rotating machines, focusing especially on the diagnosis of asynchronous motors of high power. Due to the importance of maintaining the trouble-free condition of these machines with regard to serviceability, the importance of their diagnosis is growing. Due to inappropriate working conditions or for many other reasons, different types of malfunctions may occur in the machine. The list and the way of occurrence of possible failures are included and explained in this thesis. With the growing age of the machine, it is important to check the insulation status through insulation testing. These tests are performed in the practical part of the thesis and the results are presented. In the case of asynchronous machines, each anomaly leaves a signature in the form of an electrical, magnetic or vibrational signal. These signals are analyzed and evaluated using a specific measuring equipment with the intention of deciding on the current state of the machine. Motor current signature analysis (MCSA) is considered to be the main diagnostic method of asynchronous machines in this thesis. This method is described in detail in this paper and is being applied in electrical engineering.
5

On impacts and ride-through of voltage sags exposing line-operated AC-machines and metal processes

Carlsson, Fredrik January 2003 (has links)
During the last decade, power quality has been recognised asa global problem. Among different types of power qualityproblems, voltage sags have been identified to be one of themost severe problems for different process industries. The mostcommon reason to voltage sags is lightning strikes in powerlines. Protection equipment, usually located at switchyards,disconnect faulted power lines as soon as possible, which isapproximately 100 ms. Thus, the duration of voltage sags areapproximately 100 ms. The sensitivity to voltage sags ofelectrical equipment in process industries can be observed asfor instance malfunction, automatic turnoff or damages. This thesis gives an overview of three metals processes withfocus on the sensitivity to voltage sags and interruptions. Theinherent energy in the process is used to find the sensitivity.This energy may also be used to obtain "ride-through" for theprocesses. The three metals processes are a blast furnaceprocess, a hot rolling mill process and a cold rolling millprocess. The main attention in this thesis is paid to the blastfurnace process, which is powered by a line-operatedsynchronous machine. The thesis shows that the protection equipment forelectrical machines can be adjusted to avoid unnecessaryshutdowns. It is also explained why there are high torque andcurrents during voltage sags as well as after voltage sags. Itis shown that the first peak torque and current during thevoltage sags is almost proportional to the voltage change, thatis the voltage magnitude before the voltage sag minus thevoltage magnitude during the voltage sag. The first peak torqueand current after the voltage sag depends sinusoidal-like onthe duration of the voltage sag and almost proportional to thevoltage change during the voltage sag. There is no fluxsaturation during voltage sags, however after voltage sagssaturation is very likely to occur. The thesis explains why andalso how the flux is changed during and after voltage sags. The duration of voltage sags is in many cases set by theprotection equipment located in switchyards. It is shown thatthe durations of voltage sags can be changed to durations thatwill cause less peak torque and current after voltage sags forline-operated AC-machines. It is also shown how this istheoretically achieved. <b>Keywords:</b>Rolling mill, Blast furnace, Power Quality,Synchronous machine, Asynchronous machine, Voltage sag, Voltageinterruption, Ride-through, Process disturbances, Simulation,Modelling
6

On impacts and ride-through of voltage sags exposing line-operated AC-machines and metal processes

Carlsson, Fredrik January 2003 (has links)
<p>During the last decade, power quality has been recognised asa global problem. Among different types of power qualityproblems, voltage sags have been identified to be one of themost severe problems for different process industries. The mostcommon reason to voltage sags is lightning strikes in powerlines. Protection equipment, usually located at switchyards,disconnect faulted power lines as soon as possible, which isapproximately 100 ms. Thus, the duration of voltage sags areapproximately 100 ms. The sensitivity to voltage sags ofelectrical equipment in process industries can be observed asfor instance malfunction, automatic turnoff or damages.</p><p>This thesis gives an overview of three metals processes withfocus on the sensitivity to voltage sags and interruptions. Theinherent energy in the process is used to find the sensitivity.This energy may also be used to obtain "ride-through" for theprocesses. The three metals processes are a blast furnaceprocess, a hot rolling mill process and a cold rolling millprocess. The main attention in this thesis is paid to the blastfurnace process, which is powered by a line-operatedsynchronous machine.</p><p>The thesis shows that the protection equipment forelectrical machines can be adjusted to avoid unnecessaryshutdowns. It is also explained why there are high torque andcurrents during voltage sags as well as after voltage sags. Itis shown that the first peak torque and current during thevoltage sags is almost proportional to the voltage change, thatis the voltage magnitude before the voltage sag minus thevoltage magnitude during the voltage sag. The first peak torqueand current after the voltage sag depends sinusoidal-like onthe duration of the voltage sag and almost proportional to thevoltage change during the voltage sag. There is no fluxsaturation during voltage sags, however after voltage sagssaturation is very likely to occur. The thesis explains why andalso how the flux is changed during and after voltage sags.</p><p>The duration of voltage sags is in many cases set by theprotection equipment located in switchyards. It is shown thatthe durations of voltage sags can be changed to durations thatwill cause less peak torque and current after voltage sags forline-operated AC-machines. It is also shown how this istheoretically achieved.</p><p><b>Keywords:</b>Rolling mill, Blast furnace, Power Quality,Synchronous machine, Asynchronous machine, Voltage sag, Voltageinterruption, Ride-through, Process disturbances, Simulation,Modelling</p>
7

Condições de existência de autoexcitação em geradores de indução conforme suas condições operativas / Conditions for self-excitation of generators according to its operating conditions

Mayer, Giovano 10 December 2012 (has links)
Made available in DSpace on 2017-07-10T17:11:51Z (GMT). No. of bitstreams: 1 Giovano Mayer.pdf: 9964402 bytes, checksum: fa8e2023cd08bf7b10d7d806375b1277 (MD5) Previous issue date: 2012-12-10 / The use of alternative sources of energy requires electromechanical conversion equipments that exhibit low installation, operating and maintenance costs. In such way, small energy resources that are not connect to the power system (PS) can be benefited by the use of squirrel-cage induction generators (IG) which show such characteristics. When operating in an isolated mode, the IG is called SEIG - Self Excited Induction Generator, and in this configuration its self excitation is promoted through the connection of appropriate capacitors to the terminals of the machine stator. The existence of self-excitation in the IG depends on the value of the capacitor connected to the stator, the mechanical velocity and the load. This work aims to study the conditions of existence of self-excitation in induction generators having in mind applications in isolated generators systems. Towards this goal, initially the conditions for the existence of self-excitation are stated in terms of appropriate parameters, units and quantities, so as to highlight its relations with the operative characteristics of the machine. It is considered that the induction generator is connected to a load that contains both reactive and active components, parameterized in terms of its rated power. The self-excitation capacitors are represented by its reactive power, called self-excitation reactive power (PRAE). Self-excitation existence regions are defined which explicitate conditions for the existence and maintenance of self-excitation over, a region of operating conditions (OR) of the generator. Through the analysis of the existence of the self-excitation over the OR and the parameterization of the PRAE and the load in terms or rated power, procedures for SEIG design are established. With these procedures, the design of the SEIG is defined by the maximum load power, the worse load power factor condition, and the minimum self-excitation speed of the generator. The process of self-excitation of the generator and the design procedures are analyzed with the aid of dynamic simulations of the SEIG complete model, including the non linear model of the magnetizing inductance representing the magnetic saturation. A laboratorial bench was developed to allow studies with asynchronous generation, in particular with the SEIG. The parameters of the generator were identified experimentally and used all along the work, especially in the dynamic simulations showed. The results were also compared with experimental data collected from self-excitation tests performed with the developed laboratory bench. / A utilização de fontes alternativas de energia requer equipamentos de conversão eletromecânica que apresentem baixos custos de implantação, operação e manutenção. Desta forma, pequenos recursos energéticos não ligados ao sistema elétrico de potência (SEP) podem ser beneficiados pelo emprego do gerador de indução (GI) com rotor em gaiola, que apresenta tais características. Quando operado de forma isolada, o GI é denominado de SEIG Self Excited Induction Generator, e nesta configuração sua autoexcitação é promovida através do acoplamento de capacitores apropriados aos terminais do estator da máquina. A existência da autoexcitação no GI depende do valor do capacitor conectado ao estator, da velocidade mecânica e da carga. Este trabalho tem por objetivo estudar as condições de existência da autoexcitação em geradores de indução visando sua aplicação em sistemas isolados de geração. Neste sentido, inicialmente as condições de existência de autoexcitação são colocadas em termos de parâmetros, unidades e grandezas apropriadas, a fim de explicitar as relações com as características operativas da máquina. Também é considerado que o gerador de indução é acoplado a uma carga que contém componentes tanto ativos quanto reativos parametrizados em termos de potência. Os capacitores de autoexcitação são representados por sua potência reativa denominada de potência reativa de autoexcitação (PRAE). São definidas regiões de existência de autoexcitação explicitando condições para a existência e a manutenção da autoexcitação em torno de regiões operativas (RO) do gerador. Através da análise da existência da autoexcitação em torno da RO e da representação da PRAE e da carga em termos de potência, são estabelecidos procedimentos de projeto do SEIG. Com estes procedimentos, o dimensionamento do SEIG fica em função da carga máxima a ser acionada, da pior condição de fator de potência da mesma e da velocidade mínima de autoexcitação do gerador. O processo de autoexcitação do gerador e os procedimentos de projeto são analisados com o auxílio de simulações dinâmicas do modelo completo do SEIG, incluindo o modelo não linear da indutância de magnetização representando a saturação magnética. Uma bancada laboratorial foi desenvolvida para possibilitar estudos com geração assíncrona, em particular com o SEIG. Os parâmetros do gerador foram levantados experimentalmente e utilizados em todo o trabalho, inclusive nas simulações dinâmicas apresentadas. Os resultados foram confrontados também com dados experimentais de testes de autoexcitação obtidos com a bancada desenvolvida.
8

Trakční pohon elektromobilu napájený vodíkovým palivovým článkem / Electrocar traction drive supplied with the hydrogen fuel cell

Pokálený, Jan January 2008 (has links)
The topic of this diploma thesis is a traction drive of electrocar with fuel cell. The drive is supplied with hydrogen fuel cell with power of 2 kW. The traction drive consists of the three-phase DC/AC converter and the asynchronous machine. The main part of this work is a creation of the mathematical model of the traction drive in program Matlab–Simulink.
9

Regulace příkonu přečerpávacích vodních elektráren v čerpadlovém provozu / Regulation of Pumped Storage Power Plants Inputs Under the Pumped Operating Condition.

Lorenz, Tomáš January 2008 (has links)
This paper focuses on the Double Fed Induction Machine in the Pumped Storage Power Plants. It includes listing of this plants in the world, where such a technology is used; principle of Double Fed Induction Machine, its usage with variable speed, advantages and disadvantages and also experience of its usage.
10

Náhradní zapojení asynchronních strojů / Substituting circuit of an induction machine

Běloušek, Radim January 2011 (has links)
Although induction motors are the simplest and most working reliability machines, is the identification of the parameters of their substituting circuit very difficult. There is solved the identification of the parameters of the substituting circuit in the T-network and ? –network in this work. The work also includes the proposal of magnetic circuit of the induction motor, the calculation of magnetizing and leakage inductances and resistances of the machine. The conclusion of the work is devoted to the sensitivity analysis of current and torque characteristics of induction motor upon the change of the single parameters of the substituting circuit.

Page generated in 0.073 seconds