• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 324
  • 56
  • 34
  • 23
  • 21
  • 20
  • 13
  • 4
  • 4
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 603
  • 603
  • 195
  • 174
  • 166
  • 118
  • 111
  • 92
  • 91
  • 75
  • 75
  • 71
  • 62
  • 61
  • 61
  • 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.
131

Análise da mobilidade urbana voltada para inclusão de veículos elétricos de carga visando uma logística sustentável. / Sem título em inglês

Chaud, Carolina Attas 27 May 2013 (has links)
Esta tese tem por objetivo elaborar uma metodologia integrada de análise do impacto e do desenvolvimento do veículo elétrico ao longo do tempo atrelado à inserção de estações de carregamento em grandes cidades. Esta metodologia está dividida em duas etapas. A primeira representa a caracterização do veículo em termos das variáveis que determinam o seu desempenho, tais como: avaliação das velocidades em (Km/h); a distância percorrida em (Km); fonte de energia (acumuladores eletroquímicos); sistema de acionamento dos veículos elétricos determinado como motores elétricos em função da potência (W) e da Tensão (V). Ainda, metodologicamente foi desmembrado em 4 ciclos. A segunda retrata sobre um estudo voltado para inserção de estações de carregamento em uma metrópole como a cidade de São Paulo analisando o comportamento otimizado da oferta de energia elétrica na cidade em questão, diante de diferentes taxas hipotéticas de penetração de veículos elétricos, para diferentes perfis de recarga dos veículos (recarga inteligente e sem controle). Foi realizado um estudo comparativo de possíveis ganhos ambientais, econômicos, sociais e políticos com a inserção desses veículos movidos a bateria substituindo os movidos a diesel. Bons resultados, tanto do ponto de vista ambiental (dada a redução do número de emissões e de veículos), quanto de competitividade (custos em geral), puderam ser observados, ratificando e estimulando o uso desse tipo de conceito. Assim, com o intuito de promover a mobilidade elétrica com vistas à sustentabilidade do setor de transportes, surgem novas propostas de arranjos das formas de entregas nas cidades como meio de solucionar os transtornos dessa circulação de mercadorias (seja pela intrusão poluição sonora e visual, aumento do número de emissões). / This thesis aims at developing an integrated methodology for analyzing and impact the development of electric vehicle over time pegged the inclusion of charging stations in major cities. This methodology is divided into two stages. The first step is the characterization of the vehicle in terms of the variables that determine its performance such as: evaluation of speeds (km / h); energy source (electrochemical batteries); drive system of electric vehicles such as electric motors determined as a function of power (W) and voltage (V). Still, methodologically was divided into 4 cycles. The second case of the study portrays the insertion of charging stations in a metropolis like São Paulo investigating the optimal mix of electricity supply in Brazil, in the long term, for different hypothetical rates of electric vehicles penetration, and different recharging profiles for vehicles (smart and dumb recharging). Good results, either under the environmental point of view (reduction of pollution levels and of moving vehicles), or under the competitive framework (cost reduction), were observed, which endorse and stimulate the adoption of this novel concept. But, due to the growing volumes of urban cargo, mainly in the CBDs, the subject urban cargo is receiving much more attention recently, particularly when proposing measures to improve environmental conditions in these centers.
132

Development of a Smart Charging Algorithm for Electric Vehicles at Home

Segelsjö Duvernoy, Rebecca, Lundblad, Johanna January 2019 (has links)
The purpose of this bachelor thesis is to develop a smart charging algorithm for electric vehicles (EVs) and examine the potential of the smart charging scheme, compared to uncontrolled charging scheme at residential houses with an installed photovoltaic (PV) system. The thesis examines if smart charging can increase the photovoltaic self-consumption and self-sufficiency of houses. Also, the thesis will evaluate if the smart charging scheme can reduce the household peak loads compared to the uncontrolled charging scheme. The presented results show that the implementation of the proposed algorithm will reduce the household peak load on average by 38.64 percent at a house with an installed PV system. The self-consumption and self-sufficiency increased by 4.69 percent and 4.97 percent when the smart charging algorithm was applied. To increase the credibility of the developed model a sensitivity analysis considering a number of houses and vehicles was done.  From the results, it can be concluded that the proposed smart charging algorithm could be an option to reduce the household peak load and increase the usage of renewable energy sources.
133

Design of Single Phase Boost Power Factor Correction Circuit and Controller Applied in Electric Vehicle Charging System

Liu, Ziyong 14 July 2016 (has links)
"In this thesis, based on the existing researches on power factor correction technology, I analyze, design and study the Boost type power factor correction technology, which is applied in the in-board two-stage battery charger. First I analyzed the basic working principle of the active power factor corrector. By comparing several different topologies of PFC converter main circuit and control methods, I specified the research object to be the average current control (ACM) boost power factor corrector. Then I calculated and designed the PFC circuit and the ACM controller applied in the first level charging of EVs. And I run the design in Simulink and study the important features like power factor, the input current waveform and the output DC voltage and the THD and odd harmonic magnitude."
134

Um Sistema de Informações Geográficas para Gestão de Energia Elétrica Móvel - SIGGENELM / A geographic information system for management of mobile electric power - SIGGENELM.

Fernando Palma Guimarães Pereira 14 September 2010 (has links)
Um problema que as empresas distribuidoras de energia elétrica convivem são as quedas repentinas no fornecimento, causando inúmeros prejuízos tanto para essas empresas quanto para seus consumidores. Essa dissertação apresentará uma ferramenta que utilizará conhecimentos de sistemas de informações geográficas junto com o uso de inferência nebulosa para orientar a disposição de veículos híbridos (elétricos e à combustão) que podem operar como mini-usinas elétricas no abastecimento de localidades que esteja necessitando de energia em um determinado momento. Para isso, será levantada uma base de dados com características dos veículos híbridos e locais necessitados, dados esses que alimentarão um sistema nebuloso agregado à ferramenta MapServer e a um SIG (Sistema de Informações Geográficas) para, dessa forma, mostrar como saída do sistema qual veículo estará mais apto naquele instante para abastecer o local da demanda de energia. / A problem that electric energy companies have to face is the power outage, which causes innumerable damages for both companies and consumers. This dissertation describes a tool that joins Geographic Information Systems knowledge to Fuzzy Logic knowledge to guide the distribution of hybrid vehicles (electric and combustion) that can operate as mini electric power plants to supply places that need electrical power. For this, a database will be built with the characteristics of vehicles and places in need. The data will supply a Fuzzy system joined to a MapServer tool and a GIS (Geographic Information System), showing which vehicle will be more capable in that moment to supply the place in energy demand.
135

Análise de sistemas fotovoltaicos para veículos elétricos experimentais de baixo custo

Neves , Gustavo de Souza 16 March 2016 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-30T09:23:03Z No. of bitstreams: 2 Dissertação - Gustavo de Souza Neves - 2016.pdf: 2403103 bytes, checksum: e89c1c7d2a7ed732e3b4cd3a17b311ce (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-30T09:23:52Z (GMT) No. of bitstreams: 2 Dissertação - Gustavo de Souza Neves - 2016.pdf: 2403103 bytes, checksum: e89c1c7d2a7ed732e3b4cd3a17b311ce (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-30T09:23:52Z (GMT). No. of bitstreams: 2 Dissertação - Gustavo de Souza Neves - 2016.pdf: 2403103 bytes, checksum: e89c1c7d2a7ed732e3b4cd3a17b311ce (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-16 / Conventional means of transportation have a significant impact on people's lives, which depend on the current model to perform their routine activities. Families can expend up to 20% of their income on transport. On the other hand, internal combustion vehicles emit gases that impair nature, have low efficiency reaching a maximum 30% yield. In contrast, the electric vehicle has up to 90% efficiency and does not emit harmful gases directly. These factors contribute to the increase of financial and energy waste. This study aims to contribute to minimizing these impacts through analysis of an electric propulsion system of low cost, powered by photovoltaic source to be installed in a vehicle structure of PVC (Polyvinyl Chloride). The use of this renewable energy source enables the implementation of a photovoltaic power generation system, stored in lead acid batteries used in most of vehicles. After analysis of decision matrix, it was determined the most appropriate model that supports the proposal economically and evaluated electric DC motors found in conventional vehicles. These it was found that the engine of the windshield wipers can be used in vehicle propulsion system. To control the entire electrical system was used PIC micro controller, responsible for driving the motors through H bridge, consisting of MOSFET transistors. The simulation of this control system was held at the Proteus®. / Os meios de transportes convencionais têm impacto relevante na vida das pessoas, as quais dependem do modelo atual para realização de suas atividades rotineiras. Famílias de classe média dispendem até 20% de sua renda com transportes. Por outro lado, veículos de combustão interna emitem gases que contribuem para o efeito estufa, são de baixa eficiência, com no máximo 30% de aproveitamento. Em oposição, o veículo elétrico possui até 90% de eficiência e não emite gases de efeito estufa diretamente. Esses fatores contribuem com o aumento de desperdício financeiro e energético. Este estudo visa colaborar com a minimização destes impactos, por meio da análise de um sistema propulsor elétrico de baixo custo, alimentado por fonte fotovoltaica a ser instalado em um veículo de estrutura em PVC (Policloreto de Vinila). A utilização dessa fonte de energia renovável possibilita a implantação de um sistema de geração de energia fotovoltaica, armazenada em baterias de chumbo-ácido, utilizadas em veículos ã combustão. Após anáslise por matriz de decisão, foi determinado o modelo mais adequado que atende ã proposta de forma econômica e avaliados motores elétricos de corrente contínua, encontrados em veículos convencionais. Destes se verificou que os motores de limpadores de para-brisa podem ser empregados no sistema de propulsão do veículo. Para controlar todo o sistema elétrico foi utilizado o micro controlador PIC, responsável pelo acionamento dos motores através de ponte H, constituídas por transistores MOSFET. Foi realizada a simulaço desse sistema de controle no programa Proteus®.
136

Análise da mobilidade urbana voltada para inclusão de veículos elétricos de carga visando uma logística sustentável. / Sem título em inglês

Carolina Attas Chaud 27 May 2013 (has links)
Esta tese tem por objetivo elaborar uma metodologia integrada de análise do impacto e do desenvolvimento do veículo elétrico ao longo do tempo atrelado à inserção de estações de carregamento em grandes cidades. Esta metodologia está dividida em duas etapas. A primeira representa a caracterização do veículo em termos das variáveis que determinam o seu desempenho, tais como: avaliação das velocidades em (Km/h); a distância percorrida em (Km); fonte de energia (acumuladores eletroquímicos); sistema de acionamento dos veículos elétricos determinado como motores elétricos em função da potência (W) e da Tensão (V). Ainda, metodologicamente foi desmembrado em 4 ciclos. A segunda retrata sobre um estudo voltado para inserção de estações de carregamento em uma metrópole como a cidade de São Paulo analisando o comportamento otimizado da oferta de energia elétrica na cidade em questão, diante de diferentes taxas hipotéticas de penetração de veículos elétricos, para diferentes perfis de recarga dos veículos (recarga inteligente e sem controle). Foi realizado um estudo comparativo de possíveis ganhos ambientais, econômicos, sociais e políticos com a inserção desses veículos movidos a bateria substituindo os movidos a diesel. Bons resultados, tanto do ponto de vista ambiental (dada a redução do número de emissões e de veículos), quanto de competitividade (custos em geral), puderam ser observados, ratificando e estimulando o uso desse tipo de conceito. Assim, com o intuito de promover a mobilidade elétrica com vistas à sustentabilidade do setor de transportes, surgem novas propostas de arranjos das formas de entregas nas cidades como meio de solucionar os transtornos dessa circulação de mercadorias (seja pela intrusão poluição sonora e visual, aumento do número de emissões). / This thesis aims at developing an integrated methodology for analyzing and impact the development of electric vehicle over time pegged the inclusion of charging stations in major cities. This methodology is divided into two stages. The first step is the characterization of the vehicle in terms of the variables that determine its performance such as: evaluation of speeds (km / h); energy source (electrochemical batteries); drive system of electric vehicles such as electric motors determined as a function of power (W) and voltage (V). Still, methodologically was divided into 4 cycles. The second case of the study portrays the insertion of charging stations in a metropolis like São Paulo investigating the optimal mix of electricity supply in Brazil, in the long term, for different hypothetical rates of electric vehicles penetration, and different recharging profiles for vehicles (smart and dumb recharging). Good results, either under the environmental point of view (reduction of pollution levels and of moving vehicles), or under the competitive framework (cost reduction), were observed, which endorse and stimulate the adoption of this novel concept. But, due to the growing volumes of urban cargo, mainly in the CBDs, the subject urban cargo is receiving much more attention recently, particularly when proposing measures to improve environmental conditions in these centers.
137

Contribution à l'analyse de l'impact des véhicules électrifiés sur le réseau de distribution d'électricité. / Contribution to the analysis of the impact of electric vehicles on the electricity distribution grid

Gaonac'h, Thomas 28 September 2015 (has links)
Depuis quelques années de nombreux modèles de véhicules électriques et hybrides rechargeables sont disponibles à la vente. Les prévisions annoncent des niveaux de pénétration importants pour ces prochaines années. En effet, l’État français a annoncé deux millions de véhicules électrifiés pour 2020. Les véhicules électriques impactent les réseaux d’électricité en se rechargeant, c’est alors que les flux électriques dans les réseaux évoluent. Cette recharge qui induit un changement du dimensionnement du réseau est abordée dans ce manuscrit, qui s’attache à évaluer ce changement. De plus, avec le développement de la thématique des “smart grid”, les véhicules électrifiés peuvent avoir un intérêt pour la conduite du système électrique. Cette étude a pour objectif s’attachera aussi à tenter de déterminer l’équilibre entre intérêts des véhicules électrifiés dans ce contexte et difficultés (sous la forme de coûts) qu’ils pourraient rencontrer s’ils participaient à la conduite du système.L’impact des véhicules électrifiés se concentre principalement sur les réseaux de distribution d’électricité. Dans les réseaux de distribution d’électricité, les lignes et les câbles sont des infrastructures indispensables. Alors que de nombreuses études s’intéressent au dimensionnement des transformateurs du réseau d’électricité, peu d’entre elles analysent les lignes et les câbles du réseau. Une volonté de combler ce manque est alors apparue. Ce manuscrit traite la problématique du dimensionnement des conducteurs, des lignes et des câbles du réseau de distribution d’électricité. Les véhicules électrifiés peuvent également être utilisés comme moyen de stockage de l’électricité, afin d’améliorer la conduite des réseaux d’électricité. L’étude s’intéresse également à l’évaluation de l’impact sur les conducteurs de l’utilisation des véhicules électriques et hybrides rechargeables comme moyen de stockage (donc comme moyen de conduite du système). / In recent years many models of electric and plug-in hybrid vehicles are available for sale. The forecasts predict high levels of penetration in the coming years. Indeed, the French government announced two million electric vehicles by 2020. Electric vehicles impact the electric grid by recharging, changing electricity flows in the grid. Electric vehicles charging changes the manner of sizing the grid which is the topic of this manuscript. Moreover, with the development of the smart grids, electric vehicles may have an interest as actor of the electrical system. This study also focuses on trying to determine the balance between interests of electrified vehicles in this context and challenges (in the form of costs) they might encounter if they are involved in the operation of the electric system.The impact of electric vehicles mainly focuses on the distribution grid lines and cables are a major infrastructure of the distribution grid. While many studies focus on electric transformers sizing, few of them analyze the lines and cables of the grid. A desire to fill that gap then appeared. This manuscript deals with the problem of sizing lines' and cables' conductors of the electric distribution grid. Electric vehicles can also be used as electricity storage device to improve the operation of electricity networks. The study also assesses the impact on grid conductors of electric vehicles use for storage (i.e. as a means for operating the system).
138

Parallel Hybridization of a Heavy-Duty Long Hauler

Eriksson, Tommie January 2015 (has links)
Long haulage of heavy-duty trucks weighing over 15-ton stands for nearly 50% of the fuelconsumption among trucks, making them the most fuel consuming category. This indicatesthe potential benefits in improving the fuel efficiency for said category. Hybridization is onepossible solution.Hybrid vehicles are vehicles with two or more power sources in the powertrain. Differentpowertrain configurations, hybridization levels and hybrid concepts are best suitedfor different applications. With prices for fossil fuels constantly rising hybridization is animportant technology to improve fuel efficiency.Different variations of configurations and concepts enables many choices when decidingon a hybrid driveline. A simulation tool for efficiently comparing various hybrid drivelineswould be a great asset when deciding on a configuration for a certain vehicle application. Forthis thesis the application in focus is the previously mentioned category, a heavy duty longhauler weighing 36-ton.The modeling approach used for the simulation tool is called quasistatic modeling or"backward modeling". This name comes from, based on a chosen drive cycle, the resistingforces which act on the vehicle can statically be calculated at each step from the velocityprofile. The required power to drive along the drive cycle can then be calculated backwardswithin the powertrain resulting in a fuel consumption for the combustion engine. For thisthe free QSS-toolbox for Matlab Simulink has been used as a base and modified when needed.The configuration chosen to be implemented is a parallel electric hybrid and was chosenfor its good characteristics for the type of driving highways provide. For this configurationtwo types of controllers are used, one being an Equivalent Consumption Minimization Strategycontroller and the other a simple, rule based heuristic controller.The results for both controllers show small benefits with hybridization of the longhauler compared with the conventional which in the long run would make bigger differencebecause of the large consumption in whole. A sensitivity analysis was also done showingthat improving conventional vehicle parameters can be as beneficial as hybridization.
139

Case Study of Photovoltaics and Electric Vehicle Charging in a Low-Voltage Distribution Grid

Gustafsson, Anton January 2019 (has links)
This thesis investigates the effects from a grid connection of photovoltaics and electric vehicle charging in a low-voltage distribution grid. The study has taken place on behalf of Norrtälje Energi AB, and the object of study is a customer in one of their rural grids. Due to reported disturbances by the customer, a Magtech Voltage Booster (MVB) was installed at the point of common coupling. To evaluate the situation, three power quality measurements were analysed. Furthermore, a model of the distribution grid was developed in OpenDSS. The main conclusion of this thesis is that the disturbances seems to be caused by temporary voltage drops (below 195.5 V) during charging hours. This situation continues to create problems even though the MVB boosts and balances the voltage. The power quality measurements showed that the voltage unbalance, during charging hours, violated the limit both before and after the MVB-installation. Another significant conclusion in this thesis is that the MVB does not seem to improve the power quality, on the contrary it deteriorates the power quality with regards to rapid voltage change and harmonic content. Furthermore, the OpenDSS-model was able to predict the temporary voltage drops. And the model also resulted in voltage unbalance comparable to the measurements. The model also displayed how the voltage unbalance and harmonic content mitigated to other parts of the grid, and it became clear that it is only the closest neighbour that is in the risk of deteriorated power quality.
140

Comparison of Switched Reluctance Motor and Double Stator Switched Reluctance Motor

Neupane, Nirdesh 20 December 2018 (has links)
This thesis is concerned with the design and analysis of Switched Reluctance Motor (SRM) and its improved structure Double Stator Switched Reluctance Motor (DSSRM). Three configurations of SRM viz. Inner Stator, Outer stator and Double Stator are designed and simulated in ANSYS Maxwell Suite. Design parameters are chosen by aiming optimum performance of motor after literature review and analytical study of the motor. SRM is not a line start machine, so power converter circuit is required to excite the motor. Without proper switching of current, desired torque is not obtained in SRM. The converter circuit and switching unit is built in Maxwell Circuit Editor Tools. Both magnetostatics and transient analysis is performed to investigate motion torque, torque ripple, normal force and radial force. A good comprehensive comparison of three different types of SRMs based on their torque profile and force densities is presented. Simulation performed verified better performance of DSSRM.

Page generated in 0.075 seconds