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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.
261

Willans Line Modeling for Powertrain Analysis and Energy Consumption of Electric Vehicles

Harvey, Daniel R. 01 July 2021 (has links)
With electric vehicles becoming increasingly prevalent in the automotive market consumers are becoming more conscientious of total driving range. In light of this trend, reliable and accurate modeling methods are necessary to aid the development of more energy efficient vehicles with greater drivable range. Many methods exist for evaluating energy consumption of current and future vehicle designs over the US certification drive cycles. This work focuses on utilizing the well-established Willans line approximation and proposes a simplified modeling method to determine electric vehicle energy consumption and powertrain efficiency. First, a backwards physics-based model is applied to determine tractive effort at the wheel to meet US certification drive cycle demand. Second, the Willans line approximation then augments the tractive effort model and parameterizes the vehicle powertrain to establish a bi-directional power flow method. This bi-directional approach separates propel and brake phases of the vehicle over the certification City and Highway drive cycles to successfully isolate the vehicle powertrain from non-intrinsic losses, such as parasitic accessory loads. The proposed method of bi-directional modeling and parameter tuning provides significant insight to the efficiency, losses, and energy consumption of a modeled electric vehicle strictly using publicly available test data. Results are presented for eight electric vehicles with production years varying from 2016 to 2021. These electric vehicles are chosen to encapsulate the electric vehicle market as performance electric vehicles to smaller commuter electric vehicles are selected. All vehicles are modeled with an accessory load constrained between 300 and 850 W and a regenerative braking ("regen") low-speed cutoff of 5 mph with six of the eight vehicles modeled with a regenerative braking fraction of 94%. The bi-directional Willans line is then tuned to reach agreement with the net EPA energy consumption test data for each vehicle with the results presented as representative of the chosen vehicle. Lastly, a transfer function relating major model inputs to the output is derived and lends considerable insight for the sensitivity of the modeling method. Sensitivity of the proposed modeling method is conducted for a 2017 BMW i3 with the model deemed reasonably resilient to changes in input parameters. The model is most sensitive to changes in powertrain marginal efficiency with a 6% decrease of marginal efficiency leading to a 0.404 kW and 0.793 kW cycle average net battery power increase for the City and Highway drive cycles respectively. Additionally, the model is also sensitive to changes in vehicle accessory load with a direct relationship between increases of vehicle accessory load to increases of cycle average net battery power for the City and Highway cycles. The sensitivity results justify the use of the proposed model as a method for evaluating vehicle energy consumption and powertrain efficiency solely using publicly available test data. / Master of Science / Developing robust and accurate methods for analyzing electric vehicle energy consumption and powertrain efficiency is of great interest. For the purposes of this paper, powertrain refers to a motor / inverter pair which is coupled to a simple gear reduction for torque multiplication. Many vehicles are designed with motors of varying power and torque capabilities which can present challenges when attempting to effectively compare electric vehicles from different manufacturers. The proposed modeling method presented in this work utilizes public test data to derive detailed vehicle and powertrain information. Vehicle energy consumption is also modeled and compared to net EPA test data. Eight electric vehicles are modeled with each vehicle representing a specific segment of the current electric vehicle market. A bi-directional Willans line is applied to model the propel and brake phases of each electric vehicle over the US certification drive cycles. The bi-directional approach effectively isolates the vehicle powertrain from non-intrinsic losses. From the derived powertrain parameters and modeled energy consumption, the proposed method is deemed accurate and highly useful for translating public test data to detailed vehicle information. Lastly, a sensitivity analysis is presented with the proposed method deemed reasonably resilient to changes in input parameters. The modeling method is most sensitive to changes of powertrain marginal efficiency and vehicle accessory load but constraining these inputs to reasonable ranges for electric vehicles proves sufficient.
262

Optimization of Distribution Systems: Transactive Energy and Resilience Enhancement

Qi, Chensen 21 May 2024 (has links)
The increasing penetration of electric vehicles (EVs) and other distributed energy resources (DERs) offers enhanced flexibility and resilience. During extreme conditions, grid-connected EVs and DERs can provide electricity service and restore critical loads when the utility system is unavailable. On the other hand, during normal operation, these proactive devices can provide ancillary services to alleviate voltage fluctuations and support frequency regulation. In comparison with other DERs, EVs are more flexible in providing ancillary services due to their mobile nature. However, the proliferation of EVs and DERs also introduces operational challenges to the distribution grid. For instance, EVs primarily fulfill their transportation needs. Uncoordinated charging of a large number of EVs can increase the burden on the distribution system. Due to the limited charging rate and battery size, it is generally impractical for a single EV to directly participate in the ancillary service market. A conventional distribution system is designed for unidirectional flow of electric energy. With the growing installation of DERs on the distribution system, the flow of electric energy is bi-directional and, therefore, there is a higher risk of protection miscoordination due to the fault currents resulting from DERs. With limited communication capability, these undetected protective device (PD) actuations can cause uncertainties and delay the service restoration process. This dissertation makes contributions to the coordination of EVs and DERs. It introduces four innovative models for EV coordination: 1) A transactive energy (TE) trading mechanism is proposed to coordinate EVs and aggregators. 2) Optimal tools are provided to assist EVs and aggregators in optimal decision making while participating in TE. 3) A charging station model is developed to allow EVs to provide ancillary service aligned with their mobile nature. 4) A utility function model is presented to capture the EV owners' behaviors for providing ancillary services and charging vehicles. Charging stations can estimate the electric energy demand and optimize ancillary service provision to meet their goals. Simulation cases validated that the proposed optimization tools can align EV owners' preferences in providing ancillary service to enhance distribution system operation flexibility. To enhance the resilience of distribution systems, two novel optimization strategies are presented: 1) An advanced outage management (AOM) is proposed to utilize smart meters and fault indicators (FIs) to identify the most credible outage scenario and fault locations. 2) An advanced feeder restoration (AFR) is developed to provide an optimal restoration strategy to enhance system resilience. The proposed optimization models have been validated with realistic simulation cases. / Doctor of Philosophy / As Electric Vehicles (EVs) and other Distributed Energy Resources (DERs) become more common, they are changing how our distribution systems work. For example, during power outages, grid-connected DERs and EVs can be deployed to sustain essential electricity services such as hospitals and communications. On the other hand, during a normal operating condition, they can help maintain the stability of our electricity systems. It is a technical challenge to integrate these new EV and DER devices into the existing power grid. For example, EVs are mainly designed for transportation. Their clustered charging patterns can significantly increase the electrical demand if they are not managed properly. Also, the limited battery capacity and charging speed make it difficult for a single vehicle to provide meaningful support to the grid operation. For the EV management side, this research is concerned with how to better integrate EVs and similar technologies into the power grid. Four key contributions of this dissertation are: 1) Developing a trading mechanism for EVs and aggregators of EVs to exchange energy and ancillary services efficiently; 2) Creating computational technologies to help these entities optimize their decisions while meeting their requirements; 3) Structuring charging station operations that cater to the preferences of EV owners while supporting grid operation; and 4) Modeling EV owners' decision-making to set optimal pricing and service strategies at charging stations. These mechanisms and strategies will allow EV owners to support the power grid while meeting their transportation needs. Moreover, the study addresses the issue of enhancement of the distribution system's capability to restore services under extreme conditions. It provides an advanced outage management method that utilizes remote monitoring and control technologies, including smart meters and fault indicators, to identify the location of electrical faults and reduce the outage areas. The advanced feeder restoration method determines an optimal strategy to restore the electricity service efficiently while keeping the distribution grid stable.
263

Multi-Speed Gearboxes for Battery Electric Vehicles: Modelling, Analysis, and Drive Unit Losses

Machado, Fabricio January 2024 (has links)
Exploring the integration of multi-speed gearboxes in electric vehicle (EV) drivetrains, this research presents a comprehensive analysis through detailed gearbox modelling, empirical traction machine testing, and analytical drive unit loss evaluations. The study utilizes two distinct automotive-grade electric machines – an axial-flux permanent magnet synchronous machine and an interior permanent magnet machine, the latter coupled with a single-speed gearbox – to demonstrate how multi-speed gearboxes can enhance drivetrain efficiency and performance for a subcompact EV. Extensive dynamometer testing, incorporating a variety of electrical and thermal conditions, characterizes both traction machines. Findings reveal that despite the incremental churning losses from additional gear pairs, two-speed gearboxes facilitate a more efficient operation of the electric machine, inverter, and gearbox, particularly when optimized through strategic gear ratio selection. Dynamometer testing under no-load conditions and at different temperatures underscores the impact of gearbox churning and bearing drag losses and the potential for their reduction. Detailed examinations of load-dependent and independent losses within the drive unit elucidate the interactions among drivetrain components across various gear ratios. Optimized two-speed gearboxes are shown to reduce vehicle energy consumption by up to 9% and increase driving range compared to conventional single-speed configurations, supported by strategic gear ratio selections and optimizations aimed at achieving vehicle performance targets, such as acceleration, gradeability, and top speed. This research contributes to advancing the field of electric vehicle technology by illustrating the complex trade-offs and potential enhancements achievable with multi-speed drivetrains, setting a precedent for future studies to refine gearbox performance and explore novel technologies to optimize powertrain performance across diverse operational landscapes. / Thesis / Doctor of Philosophy (PhD)
264

[pt] DESENVOLVIMENTO DE SISTEMA CLIMATIZADOR AUTOMOTIVO PARA AQUECIMENTO E RESFRIAMENTO / [en] DEVELOPMENT OF AN AUTOMOTIVE AIR CONDITIONING SYSTEM FOR HEATING AND COOLING

SERGIO LIBANIO DE CAMPOS 25 May 2015 (has links)
[pt] Sistemas condicionadores de ar automotivos têm sido extensivamente estudados, buscando melhor eficiência de resfriamento e redução do consumo de combustível. O presente trabalho tem como objetivo o estudo de um sistema condicionador de ar automotivo operando nos modos de resfriamento e aquecimento, este último atendendo às necessidades de conforto em dias frios nos veículos elétricos, os quais não apresentam calor de rejeito do motor, como nos veículos convencionais. Para tal foi projetado e montado, no Laboratório de Refrigeração, Condicionamento de Ar e Criogenia da PUC-Rio, um aparato experimental composto por duas câmaras de temperatura e umidade controladas, uma simulando o compartimento de passageiros e a outra, o ambiente externo. Um típico sistema condicionador de ar automotivo, composto por componentes comercialmente disponíveis e utilizados nos veículos atuais, foi dotado de válvulas direcionais, permitindo a inversão do ciclo de compressão de vapor do modo de resfriamento para o modo de aquecimento, operando neste último como bomba de calor. Dados experimentais foram levantados sob operação em regime permanente e transiente (período de partida), com temperaturas entre – 5 graus Celcius e 45 graus Celcius. Para o modo de resfriamento, seguiu-se a norma SAE J2765 e, para o de aquecimento, na ausência de normas, foram cobertas as operações em modos de recirculação do ar da cabine e de renovação com ar externo, entre as temperaturas de -5 graus Celcius e 10 graus Celcius. Foi também realizada uma simulação numérica, validada pelos dados experimentais, utilizando as equações fundamentais da termodinâmica e transferência de calor. O sistema testado mostrou-se viável na aplicação em veículos elétricos, uma vez que nestes o calor de rejeito previsto (regeneração de frenagem e efeito Joule na eletrônica de potência) não é suficiente para o conforto térmico em dias frios. Demonstrou-se que a bomba de calor consome menos energia que resistências as elétricas atualmente utilizadas. / [en] Automotive air conditioning systems have been extensively studied, searching for better cooling efficiency and reduced fuel consumption. The present work aims to study a system of automotive air conditioner operating in cooling and heating modes, the latter satisfies the needs of comfort on cold days in electrical vehicles, which do not include waste heat from the engine as the conventional vehicles. To this was designed and assembled in the Refrigeration, Air Conditioning and Cryogenics Laboratory, in Puc-Rio, an experimental apparatus consists of two chambers with temperature and humidity controlled, one, simulating the passenger compartment and the other, the external environment. A typical automotive air conditioning system, composed of commercially available components used in current vehicles is provided with a directional valve, allowing the inversion of vapor compression cooling mode to the heating mode cycle, the latter operating as a heat pump.
265

Development of an Efficient Hybrid Energy Storage System (HESS) for Electric and Hybrid Electric Vehicles

Zhuge, Kun January 2013 (has links)
The popularity of the internal combustion engine (ICE) vehicles has contributed to global warming problem and degradation of air quality around the world. Furthermore, the vehicles??? massive demand on gas has played a role in the depletion of fossil fuel reserves and the considerable rise in the gas price over the past twenty years. Those existing challenges force the auto-industry to move towards the technology development of vehicle electrification. An electrified vehicle is driven by one or more electric motors. And the electricity comes from the onboard energy storage system (ESS). Currently, no single type of green energy source could meet all the requirements to drive a vehicle. A hybrid energy storage system (HESS), as a combination of battery and ultra-capacitor units, is expected to improve the overall performance of vehicles??? ESS. This thesis focuses on the design of HESS and the development of a HESS prototype for electric vehicles (EVs) and hybrid electric vehicles (HEVs). Battery unit (BU), ultra-capacitor unit (UC) and a DC/DC converter interfacing BU and UC are the three main components of HESS. The research work first reviews literatures regarding characteristics of BU, UC and power electronic converters. HESS design is then conducted based on the considerations of power capability, energy efficiency, size and cost optimization. Besides theoretical analysis, a HESS prototype is developed to prove the principles of operation as well. The results from experiment are compared with those from simulation.
266

Acionamento de um motor síncrono de ímãs permanentes sem escovas visando aplicação em veículos elétricos

Valle, Rodolfo Lacerda 07 March 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-24T18:25:05Z No. of bitstreams: 1 rodolfolacerdavalle.pdf: 17326163 bytes, checksum: b5bfc03806c064bdf98c9890ed322936 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-25T12:14:13Z (GMT) No. of bitstreams: 1 rodolfolacerdavalle.pdf: 17326163 bytes, checksum: b5bfc03806c064bdf98c9890ed322936 (MD5) / Made available in DSpace on 2017-04-25T12:14:13Z (GMT). No. of bitstreams: 1 rodolfolacerdavalle.pdf: 17326163 bytes, checksum: b5bfc03806c064bdf98c9890ed322936 (MD5) Previous issue date: 2013-03-07 / Esta dissertação apresenta as etapas de desenvolvimento de um sistema de acionamento de um motor CC de ímãs permanentes sem escovas para aplicação em veículos elétricos de pequeno porte. O motor é acionado por um inversor fonte de tensão trifásico (VSI, Voltage Source Inverter) baseado em interruptores IGBT (Insulated Gate Bipolar Transistor). Os sinais de comutação dos interruptores são gerados por uma estratégia de modulação vetorial. Sinais gerados por três sensores de efeito Hall são usados para detectar a posição angular do rotor. O motor é controlado a partir de duas malhas. Uma malha externa controla a velocidade enquanto a malha interna controla as correntes de fase do motor. O desempenho de dois tipos de controladores foram investigados para o controle das correntes sintetizadas pelo VSI: (i) controlador proporcional– integral no sistema de coordenadas síncrono e (ii) controlador proporcional–integral com integradores em múltiplos sistemas de coordenadas rotativas. Além das malhas de controle, o sistema de acionamento foi projetado com uma estratégia de desacoplamento das correntes de controle e uma ação preditiva para compensar o efeito das tensões contra–eletromotriz trapezoidais geradas por fase pelo motor. Um protótipo experimental do sistema de 5 kW foi montado em laboratório. Os algoritmos de controle do motor e do VSI, juntamente com o algoritmo de deteção de posição do rotor foi implementado em um controlador digital de sinais TMS320F28335. Resultados experimentais são apresentados, discutidos e utilizados para validar as estratégias de controle. / This dissertation presents the development of a permanent magnet brushless DC motor drive (PMBLDC) for small electric vehicles applications. A three–phase voltage source inverter (VSI) based on IGBT (insulated gate bipolar transistor) is used to drive the electric motor. The semiconductor switches are controlled by space vector modulation (SVM). Signals from three Hall effect sensors are used to detect the rotor angular position. Two closed–loops are used to control the PMBLDC motor. The outer loop controls the rotor velocity while the inner loop controls the motor phase currents. Two types of controllers were investigated to synthesize the currents: (i) proportional– integral controller in synchronous reference frame and (ii) proportional–integral controller with multiple rotating synchronous reference frame integrators. Besides the current control loops, the drive system was designed considering the decoupling of the synthesized phase currents and a feed-forward electromotive force waveform compensation. An experimental prototype of 5 kW was built in laboratory. The motor and VSI control algorithms and the algorithm used to detect the rotor position were implemented in a TMS320F28335, digital signal controller. Experimental results are presented, discussed along with the validation of the control strategy.
267

Využití solární energie pro elektromobilitu / Use of solar energy for electromobility

Harant, Miroslav January 2019 (has links)
The thesis deals with the use of solar energy for electromobility. First, the potential of electromobility on the current market is theoretically discussed. This issue includes mainly the producers of electrically powered vehicles, the issue of electric energy storage and the real applications of fast charging and photovoltaic charging stations. In the next part, electric cars are analyzed, which use solar energy for their function and their efficiency is compared with the effiency of combustion engines. The main part of this thesis is the design of photovoltaic charging station for electric vehicles. The final part deals with the economic evaluation of the proposed charging station.
268

Využití solární energie pro elektromobilitu / Use of solar energy for electromobility

Harant, Miroslav January 2020 (has links)
The thesis deals with the use of solar energy for electromobility. First, the potential of electromobility on the current market is theoretically discussed. This issue includes mainly the producers of electrically powered vehicles, the issue of electric energy storage and the real applications of fast charging and photovoltaic charging stations. The second part of the diploma thesis deals with the measurement of electric car consumption and the evaluation of measurement results. In the next part, electric cars are analyzed, which use solar energy for their function and their efficiency is compared with the effiency of combustion engines. The main part of this thesis is the design of photovoltaic charging station for electric vehicles. The final part deals with the economic evaluation of the proposed charging station.
269

Design of a Permanent-Magnet Assisted Synchronous Reluctance Machine for a Plug-In Hybrid Electric Vehicle

Khan, Kashif Saeed January 2011 (has links)
QC 20111214
270

Co-Optimisation du Dimensionnement et du Contrôle des Groupe Motopropulseurs Innovants / Design and Control Co-Optimization for Advanced Vehicle Propulsion Systems

Zhao, Jianning 26 October 2017 (has links)
Des technologies avancées sont très demandées dans l'industrie automobile pour respecter les réglementations de consommation de carburant de plus en plus rigoureuses. La co-optimisation du dimensionnement et du contrôle des groupes motopropulseurs avec une efficacité de calcul améliorée est étudiée dans cette thèse.Les composants des groupes motopropulseurs, tels que le moteur, la batterie et le moteur électrique, sont modélisés analytiquement au niveau descriptif et prédictif afin de permettre une optimisation du contrôle rapide et une optimisation du dimensionnement scalable. La consommation d'énergie minimale des véhicules hybrides-électriques est évaluée par des nouvelles méthodes optimales. Ces méthodes – y compris Selective Hamiltonian Minimization et GRaphical-Analysis-Based energy Consumption Optimization – permettent d'évaluer une consommation minimale d'énergie avec une efficacité de calcul améliorée. De plus, la méthode de Fully-Analytic energy Consumption Evaluation (FACE) approxime la consommation d'énergie minimale sous forme analytique en fonction des caractéristiques de la mission et des paramètres de conception des composants du groupe motopropulseur. Plusieurs cas d’études sont présentées en détail par rapport aux approches de co-optimisation à bi-niveaux et à uni-niveau, ce qui montre une réduction efficace du temps de calcul requis par le processus global de co-optimisation. / Advanced technologies are highly demanded in automotive industry to meet the more and more stringent regulations of fuel consumption. Cooptimization of design and control for vehicle propulsion systems with an enhanced computational efficiency is investigated in this thesis.Powertrain components, such as internal combustion engines, batteries, and electric motor/generators, are analytically modeled at descriptive and predictive level correspondingly for the development of fastrunning control optimization and for the scalability of design optimization. The minimal fuel consumption of a hybrid-electric vehicle is evaluated through novel optimization methods. These methods – including the Selective Hamiltonian Minimization, and the GRaphical-Analysis-Based energy Consumption Optimization – are able to evaluate the minimal energy consumption with the enhanced computational efficiency. In addition, the Fully-Analytic energy Consumption Evaluation method approximates the minimal energy consumption in closed form as a function of the mission characteristics and the design parameters of powertrain components.A few case studies are presented in details via the bi-level and uni-level co-optimization approaches, showing an effective improvement in the computational efficiency for the overall co-optimization process.

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