• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 324
  • 56
  • 34
  • 23
  • 21
  • 20
  • 13
  • 4
  • 4
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 605
  • 605
  • 195
  • 174
  • 166
  • 118
  • 111
  • 93
  • 91
  • 76
  • 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.
181

Impact of electric vehicles in the steady state operation of distribution systems / Impacto de veÃculos elÃtricos na operaÃÃo em regime permanente de sistemas de distribuiÃÃo

Erasmo Saraiva de Castro 15 June 2015 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / This work aims to quantify the impact in the steady state operation of a distribution system when electric vehicles are connected. It is worth noting that the connection of them may cause significant changes in the voltage profile, in the degree of voltage unbalance and in the electrical losses of the system. In order to make this analysis, a three-phase power flow program was developed in MATLAB language. This program is based on the Ladder Iterative Technique and it contains models of overhead distribution lines, underground distribution lines, spot loads, distributed loads connected in wye and delta, step voltage regulators, capacitor banks, three-phase transformers and the model of an electric vehicle. This model allows simulation of a real electric vehicle of model Tesla Roadster, produced by Tesla Motors. The test system used in all simulations was the IEEE 13 bus. Moreover, the methodology consisted in simulate the system with the voltage regulator and without the voltage regulator under heavy load and light load conditions. The electric vehicle was connected to a specific systemâs bus and it were considered that it could work as a load or as a distributed generator with or without positive sequence voltage control. Constants configurations of the electric vehicles were considered for the heavy load and light load cases. The results of the simulations reveal there was voltage violation due to the connection of electric vehicles acting as loads in the test system under heavy load conditions without voltage regulator. When they operate as generators, they can maintain the voltage unbalance under the allowed 2%, turning the systemâs voltages more balanced. There were significant reductions when the electric vehicles acted as a load (71.1%) and as generator (77.5%) on the total real power losses when the system operated with voltage regulator on the substation and the electric vehicles operated with positive sequence voltage control (specified at 1,0 pu). / Este trabalho tem o objetivo de quantificar o impacto da conexÃo de veÃculos elÃtricos na operaÃÃo em regime permanente de um sistema de distribuiÃÃo. à visto que a conexÃo dos mesmos pode causar mudanÃas significativas no perfil de tensÃes, no grau de desequilÃbrio de tensÃo e nas perdas elÃtricas do sistema. Para realizar essa anÃlise, desenvolveu-se um programa de fluxo de potÃncia trifÃsico na linguagem MATLAB. O programa à baseado na tÃcnica iterativa de escada. Foram implementados nesse programa modelos de linhas de distribuiÃÃo aÃreas e subterrÃneas, modelos de cargas concentradas e distribuÃdas conectadas em delta e em estrela, modelos de reguladores de tensÃo, modelos de banco de capacitores, modelo de transformadores trifÃsicos e o modelo do veÃculo elÃtrico. Esse modelo permite simular o veÃculo elÃtrico Tesla Roadster da Tesla Motors. O sistema teste utilizado em todas as simulaÃÃes foi o sistema IEEE 13 barras. A metodologia utilizada consistiu em simular o sistema sem regulador de tensÃo e com o regulador de tensÃo, em carga pesada e em carga leve. O veÃculo elÃtrico foi conectado a uma barra do sistema e considerou-se que o mesmo podia funcionar como carga ou gerador distribuÃdo sem e com controle de tensÃo de sequÃncia positiva no ponto de conexÃo. Adotou-se disposiÃÃes constantes de veÃculos elÃtricos para os casos de carga pesada e carga leve. Os resultados das simulaÃÃes revelam que houve violaÃÃo de tensÃo devido à inserÃÃo de veÃculos elÃtricos atuando como carga no sistema teste em carga pesada sem regulador de tensÃo. Jà quando operam como gerador, os veÃculos elÃtricos diminuem o grau de desequilÃbrio em mÃdia, podendo mantÃ-lo abaixo do limite permitido de 2 %, tornando assim as tensÃes das barras trifÃsicas do sistema mais equilibradas. Houve reduÃÃes significativas quando os veÃculos elÃtricos atuaram como carga (71,1 %) e como gerador (77,5 %) na perda de potÃncia ativa total do sistema quando o sistema operou com regulador de tensÃo na subestaÃÃo e os veÃculos elÃtricos operaram com controle de tensÃo de sequÃncia positiva (especificada em 1,0 pu).
182

Study on Microwave-Driven Electric Vehicle for Agriculture / マイクロ波駆動農用電気車両に関する研究

Miyasaka, Juro 24 March 2014 (has links)
Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(農学) / 乙第12823号 / 論農博第2796号 / 新制||農||1025(附属図書館) / 学位論文||H26||N4818(農学部図書室) / 31310 / 京都大学農学研究科農業工学専攻 / (主査)教授 清水 浩, 教授 近藤 直, 教授 飯田 訓久 / 学位規則第4条第2項該当
183

An Agent-Based Approach for Automating the Process of Charging Plug-in Electric Vehicles

Civelek, Ülkan Fuat January 2010 (has links)
The study of Power TAC is a Multi-Agent competitive simulation test-bed, providing opportunity to simulate research and developments of electronic agents which can manage the tasks of the consumers and energy resources in a virtual energy infrastructure. According to the Power TAC scenario, Plug-in Electrical Vehicles are a special type of consumers that interact with this infrastructure and sometimes with the producers through aggregators. The aim of this study is modeling an intelligent Plug-in Electric vehicle agent for Power TAC that acts as an intermediary between Power TAC grid and vehicle owners. The proposed agent acts autonomously and is capable of making decisions about its energy needs by learning the driving behaviors and other preferences of these vehicle owners in a specified time interval. These agents will be able to make decisions about buying energy from the grid when the charging process is necessary or sell their energy back to the grid when the conditions of the electricity market are sufficiently attractive. The objective of this study is to model a Multi-Agent system for automating the process of charging the plug-in Vehicle Agents in Power TAC scenario by determining the necessary agents and the simulation environment where the agents constructed and simulated. Аs results of this study, different strategies are defined by considering the preferences of the vehicle owners and the conditions of the vehicle; thereby the agents autonomously bid behalf of their user in order to automate the process of charging.
184

UX and Service Design for Zbee Based Corporate Carsharing / UX och Service Design för Zbee baserad Företags Bildelning

Bahtiri, Blerand January 2018 (has links)
What transportation means corporations choose for satisfying their mobility needs may have an essential impact on the environment. Choosing environmental friendly, alternatives such as battery driven light electric vehicles, would mean drastically contributing to a more sustainable environment. Meanwhile as carsharing solutions, continuously rise in popularity together with other sharing economy business models so do their possibilities to satisfy the mobility needs for corporations either by them implementing their own carsharing service or by investing on external services offered by established carsharing operators. This thesis has investigated and designed for a Zbee based corporate carsharing service, to be used between the affiliates of Vinngroup in Gothenburg. A Zbee is a light electric three-wheeled vehicle. Based on user-centred service design methods, methods suggested for sharing economy solutions, as well as user experience design methods, this thesis identified that users have different individualistic needs in a workplace and prior experiences that affects how they will use the service.In order to satisfy these different needs, it was found, the system needs to provide real-time vehicle and scheduling information for ensuring the users vehicle availability and service reliability, being one of the first requirement from the users. Further the service should provide users with functions that help users through the different use phases that were identified during this work. The findings found were then presented visually by designing mobile application prototypes and testing them on participants iteratively. The final set of prototypes was further evaluated by using the System Usability Scale, an effective and popular tool for measuring the usability of products and services. This evaluation gave the scores 77.5, 92.5, 90, 87.5 and 72.5, thus this giving a mean-value of 84 and a median of 87.5. All these scores suggests the prototype has high usability.
185

Modélisation, conception et expérimentation d'un véhicule hybride léger pour usages urbains / Modeling, design and experimental test of an small urban hybrid electric vehicle

Loukakou Bounzeki Mbemba, Destiny Conscience Eland 21 December 2012 (has links)
La crise du pétrole et les contraintes écologiques obligent de nombreux constructeurs automobiles à développer des programmes de recherche importants dans le développement des véhicules électriques et hybrides électriques. Dans ce contexte, cette thèse a pour but de vérifier la faisabilité d’une chaine de traction hybride innovante consistant à partir d’unvéhicule thermique existant et à réduire la puissance du moteur thermique tout en ajoutant des moteurs intégrés dans les roues du train arrière. Ce travail a été réalisé dans le cadre d’un projet financé par l’ADEME et en collaboration notamment avec le constructeur automobile AIXAM-MEGA.Plus précisément, le travail de thèse a donc porté sur le dimensionnement des sources énergétiques, la modélisation énergétique et fonctionnelle du véhicule et enfin la réalisation et la caractérisation expérimentale du véhicule.Dans le premier chapitre, l’auteur développe une revue bibliographique relative aux véhicules hybrides électriques existants. Cela permet ensuite d’introduire le concept innovant de chaine de traction hybride décrit ci-dessus, reposant en quelque sorte sur un couplage par la route des puissances de propulsion thermiques et électriques.Dans le deuxième chapitre l’auteur aborde le dimensionnement des sources énergétiques en se focalisant sur les super-condensateurs. Il propose une approche analytique simple de calcul reposant sur les missions définies par le constructeur AIXAM-MEGA. Les modules de supercondensateurs retenus sont ensuite caractérisés expérimentalement (capacité, résistance interne, rendement de stockage…) en prenant en compte l’effet de la température.Les troisième et quatrième chapitres sont consacrés à la modélisation du véhicule. En premier lieu, le troisième chapitre aborde la modélisation énergétique du véhicule. Le véhicule a entièrement été modélisé en utilisant le formalisme de représentation énergétique macroscopique développée initialement au Laboratoire d’Électrotechnique et d’Électroniquede Puissance de Lille. Ce modèle a permis de développer le contrôle du véhicule. Ensuite, dans le quatrième chapitre, l’auteur présente la modélisation fonctionnelle du véhicule par machine d’état. Cela permet de prévoir le comportement du véhicule dans ses différentes phases de vie et de définir les transitions entre ces différentes phases. Cette étape deprototypage virtuel est essentielle afin de vérifier en amont la fonctionnalité du véhicule et sa sécurité.Enfin, le cinquième et dernier chapitre est entièrement consacré à la caractérisation expérimentale du véhicule. Les différents fonctionnements thermiques, électriques et hybrides sont testés lors de vrais essais de roulage.En conclusion, le travail de thèse a abouti à la réalisation d’un véhicule hybride. Les approches de dimensionnement des sources et de modélisation sont ainsi validées, tout en faisant également la preuve de la faisabilité d’une chaine cinématique hybride électrique avec couplage par la route. / The exhaustion, increased cost and location of fossil fuels on the one hand, and the environmental problems caused by emissions of CO2 in the atmosphere on the other hand, are forcing many automotive manufactures to develop major research programs in the designof electric vehicles and hybrid electric. In this context, this thesis aims to test the feasibility ofan innovative hybrid drivetrain consisting of a vehicle from existing heat and reduce engine power while adding motors integrated into the wheels of the rear axle. This work was conducted as part of a project funded by ADEME and also in collaboration with the car manufacturer Aixam-MEGA.More specifically, the thesis has focused on the design of energy sources, energy modeling and functional vehicle and finally the implementation and experimental characterization of the vehicle.In the first chapter, the author develops a literature review on the existing hybrid electric vehicles. This allows then to introduce the innovative concept of hybrid drivetrain described above, based somewhat on a road coupling powers of thermal and electric propulsion.In the second chapter the author discusses the design of energy sources focusing on ultracapacitors. It offers an analytical approach simple calculation based on the tasks set by the manufacturer Aixam-MEGA. Modules selected ultracapacitors are then characterized experimentally (capacity, internal resistance, storage efficiency ...) taking into account the effect of temperature.The third and fourth chapters are devoted to the modeling of the vehicle. First, the third chapter discusses the modeling efficiency of the vehicle. The vehicle has been fully modeled using the formalism of Energetic Macroscopic Representation initially developed at the Laboratory of Electrical and Power Electronics of Lille. This model has led to the development of vehicle control. Then, in the fourth chapter, the author presents the functional modeling of the vehicle state machine. This allows predicting the behavior of the vehicle in its different life phases and defining the transitions between these phases. This stage of virtual prototyping is essential to verify the functionality of the upstream and vehicle safety.Finally, the fifth and final chapter is devoted to the experimental characterization of the vehicle. The different operations thermal, electric and hybrid are tested in real taxi trials.In conclusion, the thesis has led to the realization of a hybrid vehicle. The design approaches and modeling of sources and are validated, while also demonstrated the feasibility of a hybrid electric powertrain coupling the road.
186

Strategická analýza / Strategic analysis

Pavlíček, Karel January 2013 (has links)
The goal of this master thesis is execution of a strategy analysis. The subject of this analysis is electro-mobility i.e. products and services related to electric vehicles in the Czech Republic. The theoretical part of the paper is focused on approaches used for analyses of both external factors and forces affecting particular industry. The former is mainly focused on technology, regulations and incentives. The latter analysis is based on five forces supplemented by the role of complements. Actual status of the technology an analysed product is assessed by SWOT analyses. In the conclusion, final recommendations based on overall findings are stated.
187

Decentralized scheduling of EV energy and regulation reserve services in distribution network markets

Yanikara, Fatma Selin 19 May 2020 (has links)
The electricity transmission and distribution (T&D) grid is undergoing a paradigm shift as renewable generation explodes while flexible, storage-like loads are being massively adopted. We address the intermittency and volatility issues of renewable resources in connection with spatiotemporal distribution location-specific marginal-cost-based prices (DLMPs) that guide flexible loads to utilize their significant degrees of freedom for the purpose of providing valuable storage-like services to the grid including demand response, energy charge/discharge arbitrage and regulation reserve services. Dynamic DLMPs can induce socially optimal energy and reserve schedules to be adopted by flexible load. To this end, existing transmission wholesale markets must be extended to include distribution network connected participants. Since the inclusion of the complex preferences of many flexible loads renders familiar centralized transmission market designs intractable, we propose and investigate tractable decentralized market designs with Electric Vehicle (EV) battery charging selected as the representative flexible load. We address the equilibrium existence, uniqueness, and efficiency issues that arise with decentralized market designs, using game theory techniques. We investigate various multi-hour and multi-commodity (energy and reserves) market designs including EV self-scheduling under distribution network information aware/unaware conditions, and single or multiple load aggregator(s) scheduling groups of EVs. We investigate the role of network related information in enabling partially price anticipating EVs to acquire market power and self-schedule to achieve individual benefits at the expense of social welfare. Our contribution is the proof of existence and uniqueness of decentralized market equilibria, as well as analytical and numerical comparative analysis. Secondly, we depart from the usual ideal battery assumption, employing instead a realistic two bucket model. We then develop a novel Markovian Decision Process (MDP) application to estimate the regulation tracking cost incurred over an hour by an EV charger employing an optimal controller to respond to the regulation signal which is reset every two seconds by the system operator. The hourly tracking error increases when the EV promises higher regulation reserves while at the same time demanding an achievable albeit high average charging rate. We solve the MDP repeatedly, in fact off line, to capture the impact of the average charging rate and the regulation reserves promised at the beginning of an hour to the resulting hourly regulation tracking error. We then estimate a convex closed form relationship mapping hourly charging rate and regulation reserve offerings to the expected hourly tracking error cost. These convex tracking cost functions provide crucial input to the day ahead hourly energy bids and regulation reserve offers made by individual EVs to the Day Ahead market in response to spatiotemporal DLMPs.
188

Intégration de diverses conditions de fonctionnement dans l'identification en temps réel et la gestion énergétique d'un véhicule à pile à combustible = Integrating various operating conditions into real-time identification and energy management of a fuel cell vehicle

Kandidayeni, Mohsen January 2020 (has links) (PDF)
No description available.
189

Modeling of proton exchange membrane fuel cell performance degradation and operation life

Ahmadi Sarbast, Vahid 10 September 2021 (has links)
Proton Exchange Membrane Fuel Cell (PEMFC) is the most commonly used type of hydrogen fuel cell and a promising solution for vehicular and stationary power applications. This research starts with an extensive review of the PEMFC research, including experimental testing, and performance modeling, and performance degradation modeling using relatively accurate and easy-to-use mechanistic models. Next, a new PEMFC performance degradation model is introduced by amending the semi-empirical, mechanistic performance model to support the design and control of PEMFC systems and fuel cell electric vehicles (FCEVs). The new model takes into account critical factors impacting PEMFC performance. The performance degradation due to the oxidation of catalyst platinum (Pt) and loss of active surface area is captured by fitting the degradation model parameters using experimental data to capture the observed PEMFC performance fading. The new performance degradation model is then tested and further improved under the four typical load modes that a PEMFC system experiences in a vehicular application under regular driving cycles. The model is also fitted with PEMFC experimental degradation data under different load modes to improve modeling accuracy. The new model is applied and tested using simulations of a representative FCEV. The actual power load on an 80 kW PEMFC system in the modeled FCEV was obtained using the Advanced Vehicle Simulator (ADVISOR) under the US EPA Urban Dynamometer Driving Schedule (UDDS). With the ability to predict the operation life of the PEMFC, the appropriate sizes of the PEMFC system and the energy storage system (ESS) can be determined. Improved power control and energy management can be developed to extend the operation life of the PEMFC and lower the lifecycle cost of the FCEV. / Graduate
190

EMI Characterization and Improvement of Bi-Directional DC/DC Converters

Qu, Dayu 07 October 1999 (has links)
A worldwide awareness of the environment is accelerating fuel cell vehicle development. With respect to power electronics, special requirement is on the development of high efficiency, high voltage ratio bi-directional DC/DC converter for fuel cell energy system management. In this paper, two bi-directional DC/DC converters, which are developed for Ford Motor Company’s fuel cell vehicle, are compared from different aspects. Comparison is concentrated on the circuit topology and EMI performance. Emphasis is placed on soft-switch, hard-switch, synchronized rectification, auxiliary start-up winding and their effect on EMI performance in this kind of isolated bi-directional converter. Comparison includes circuits analysis and test result. The EMI test setup is described. EMI measurements are given and explained. EMI solutions for bi-directional DC/DC converter are discussed. An EMI filter is designed and final test result is given. / Master of Science

Page generated in 0.0732 seconds