Browsing by Subject "Electric vehicle"
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Item A decision analysis of an oil company's retail strategy in the face of electric vehicle penetration uncertainty(2012-05) Jo, Dohyun; Bickel, J. Eric; Gilbert, Robert B.This thesis evaluates emerging electric vehicle technology and estimates what effect it might have on how an oil company decides on its gas station network. It is conducted using data from South Korea, a country poised for a fast adoption of electric vehicles. The study first reviews the literature to gather reasonable cases of electric vehicle penetration. Also, after researching technology-diffusion theories, the study selects a model that can well explain the literature review data. The scenarios induced by this function are utilized as the main uncertainties confronting an oil company’s network decision model. Based on a probabilistic simulation, the study finds that the effects of technology diffusion alter the priority order of an oil company’s network decision alternatives. Namely, after the overall uncertainty level rises, directly owning gas station, with its heavy initial investment, is not preferred for an oil company’s network strategy. From the result, the study also estimates the scale of the new technology’s effect. Such effect is found to be significant enough to alter a part of an oil company’s retail strategy. Nevertheless, such effect cannot be shown to be so great as to change the current retail oil market structures.Item Development of an integrated expansion evaporator and condenser unit for an advanced thermo-adsorptive battery system(2014-08) Yu, Tao; Shi, Li, Ph. D.The advanced thermo-adsorptive battery climate control system (ATB) is a highly innovative cooling and heating technology being developed by a cross-disciplinary academic and industrial team. The primary goal of this technology is to be employed in electric vehicles (EVs). In comparison with the conventional vapor-compression cooling system and the inefficient resistive heating method employed by the EVs’ industry, the ATB system is expected to offer EVs an additional 30% driving range by providing high cooling (2.5kWh) and heating (3.5kWh) storage in a lighter (<35kg) and more compact (<30L) system. The integrated expansion evaporator/condenser unit (IEECU) is one of the most crucial components comprising the ATB system. It combines the functions of an evaporator and a condenser and is designed to enhance the heat exchange between coolant and refrigerant. This thesis summarizes the work starting from the design, fabrication to characterizing process, with a particular focus on evaporation characterization. Development of ATB system and test setup including other components is covered in the rest of thesis.Item An electrical resistance-based fatigue life prediction model and its application in lithium-ion battery ultrasonic welding(2012-12) Zhao, Nanzhu; Li, Wei (Of University of Texas at Austin)Ultrasonic welding is one of the leading technologies for joining multiple, thin sheets of dissimilar materials, such as copper and aluminum, for automotive lithium-ion batteries. The performance of ultrasonic welds, particularly the fatigue life, however, has not been well studied. In this work, a theoretical fatigue life model for ultrasonically welded joints was developed using continuum damage mechanics. In the model, the damage variable was defined as a function of the increase of the joint electrical resistance, resulting in an electrical resistance-based fatigue life prediction model. The fatigue model contains two constants to be determined with experimental data, depending on different fatigue loads and joint properties. As an application, the fatigue life model was validated for Al-Cu lithium-ion battery tab joints. Mechanical fatigue tests were performed under various stress loading conditions for welds made using different welding parameters. It is shown that the developed model can be used to predict the remaining life of the ultrasonically welded battery tab joints for electric and hybrid electric vehicles by monitoring the electrical resistance change. In addition, thermal and electrical fatigue tests were performed for Al-Cu battery tab welds using simulated operating conditions of electrical vehicles. These included temperature cycling between -40 and 90 °C and current cycling of 0 to 10 A. All the tests were conducted on individual weld joints. The results showed that the thermal and electrical loads imposed insignificant effect on the electrical resistance of the battery tab joints.Item Evaluating land use impacts of self-driving vehicles and leveraging intelligently charged electrified transit to support a renewable energy grid in the Austin, Texas region(2019-12-10) Wellik, Tyler Katherine; Kockelman, KaraThis thesis is divided into two parts. The first part focuses heavily on the land use model SILO and its implementation in the Austin, Texas six-county region over a 27-year period of full adoption of self-driving vehicles. It discusses the model framework and capabilities and critically evaluates SILO’s specifications. SILO was then integrated with the agent-based transportation model MATSim for the Austin region. Land use and travel results were generated for a business-as-usual case (BAU) of 0% self-driving or “autonomous” vehicles (AVs) over the model timeframe versus a scenario where households’ value of travel time savings (VTTS) is reduced by 50%, to reflect the travel-burden reductions of no longer having to drive. A third scenario is also compared and examined against BAU to understand the impacts of rising vehicle occupancy (VO), and/or higher roadway capacities, due to dynamic ride-sharing (DRS) options in shared AV (SAV) fleets. Results suggest an 8.1% increase in average commute times when VTTS falls by 50% and VO remains unaffected (the 100% AV scenario), and a 33.3% increase in the number of households with “extreme commutes” (over 1 hour, each way) in the final model year (versus BAU of 0% AVs). When VO is raised to 2.0 and VTTS falls instead by 25% (the “Hi-DRS” SAV scenario), average commute times increase by 3.5% and the number of households with “extreme commutes” increase by 16.4% in the final model year (versus BAU of 0% AVs). The ITLUM also predicts 5.3% fewer households and 19.1% more available, developable land in the City of Austin in the 100% AV scenario in the final model year relative to the BAU scenario’s final year, with 5.6% more households and 10.2% less developable land outside the City. In addition, the model results predict 5.6% fewer households and 62.9% more available developable land in the City of Austin in the Hi-DRS SAV scenario in the final model year relative to the BAU scenario’s final year, with 6.2% more households and 9.9% less developable land outside the City. This thesis’ second part looks at how electric buses can support a power grid that relies heavily on renewable energy sources, like wind and solar. The transportation sector is a major greenhouse gas (GHG) emitter. Concurrent electrification of vehicles and investment in renewable energy is required to deeply decarbonize this and other sectors of our economies. The introduction of intermittent renewable energy sources, like solar and wind, at a large scale presents major challenges to grid operators and utility companies. This study examines the benefits and costs that a Vehicle-to-Grid (V2G) Battery Electric Bus (BEB) fleet offers Austin, Texas by buffering against sharp shifts in renewable energy production to help smooth power demands from traditional energy sources (like coal, natural gas, and nuclear power plants). A V2G BEB “smart charging” (SC) scenario’s cost and emissions were compared to those in a BEB “charge-as-needed” scenario and to those in a diesel bus scenario, for 423+ buses and over 88,000 bus-miles per day. By simply electrifying Austin’s buses, without any SC strategies, the total external cost of all of Austin’s electricity grid emissions and bus emissions falls by approximately 3.42%, amounting to over 21¢-savings per bus-mile, relative to the diesel-bus scenario. By using SC strategies, those same emission costs fell by 5.64% or over 35¢-savings per bus-mile. These emissions savings become very significant when summed over the course of a year. In the non-SC BEB scenario, emissions savings amount to approximately $6.86M/year, and in the SC BEB scenario, emissions savings reach approximately $11.3M/year. Such reductions are thanks to high renewable energy use in Austin’s power mix and because diesel fuel is much more emitting (per kWh) than power plants. From the transit operator’s perspective, a BEB fleet costs more than a diesel bus fleet, but such costs can be more than offset by renewable energy savings and emissions-costs benefits. Thanks to SC strategies, the utility manager is estimated to save 22% of their daily power-purchase cost in this case study.Item Impact of range anxiety on driver route choices using a panel-integrated choice latent variable model(2014-12) Chaudhary, Ankita; Bhat, Chandra R. (Chandrasekhar R.), 1964-; Duthie, Jennifer ClareThere has been a significant increase in private vehicle ownership in the last decade leading to substantial increase in air pollution, depleting fuel reserves, etc. One of the alternatives known as battery operated electric vehicles (BEVs) has the potential to reduce carbon footprints due to lesser or no emissions and thus the focus on shifting people from gasoline operated vehicles (GVs) to BEVs has increased considerably recently. However, BEVs have a limited ‘range’ and takes considerable time to completely recharge its battery. In addition, charging stations are not as pervasive as gasoline stations. As a result a new fear of getting stranded is observed in BEV drivers, known as range anxiety. Range anxiety has the potential to substantially affect the route choice of a BEV user. It has also been a major cause of lower market shares of BEVs. Range anxiety is a latent feeling which cannot be measured directly. It is not homogenous either and varies among different socio-economic groups. Thus, a better understanding of BEV users’ behavior may shed light on some potential solutions that can then be used to improve their market shares and help in developing new network models which can realistically capture effects of varying EV adoptions. Thus, in this study, we analyze the factors that may impact BEV users’ range anxiety in addition to their route choice behavior using the integrated choice latent variable model (ICLV) proposed by Bhat and Dubey (2014). Our results indicate that an individual’s range anxiety is significantly affected by their age, gender, income, awareness of charging stations, BEV ownership and other category vehicle ownership. Further, it also highlights the importance of including disutility caused by distance while considering network flow models with combined GV and BEV assignment. Finally, a more concentrated effort can be directed towards increasing the awareness of charging station locations in the neighborhood to help reduce the psychological barrier associated with range anxiety. Overcoming this barrier may help increase consumer confidence, resulting in increased BEV adoption and ultimately will lead towards a potentially pollution-free environment.Item Medium voltage extreme fast charger based on novel medium voltage SiC power devices(2021-08) Sen, Soumik, Ph. D.; Huang, Alex Q.; Hanson, Alex; Hebner, Robert; Feng, Xianyong; Santoso, SuryaWith an increased number of electric vehicles on the roads, there is a need for adequate charging infrastructure to serve these vehicles. Extreme fast charging technology has the potential to add 200 miles charge to electric vehicles in less than 10 minutes to provide a refueling experience comparable to gasoline vehicles. Having access to these fast charging stations can help alleviate the “range anxiety” commonly cited as a reason for consumer’s hesitation to buy an electric vehicle. This thesis presents the design and implementation of a 4.16kVac/800Vdc three phase 150kW fast charger which uses a modular single-phase single-stage isolated ac/dc power converter in each phase. Novel 7.2kV/60A SiC Austin SuperMOS devices are used as the medium voltage power electronic switches and soft-switching over the entire range of grid voltage has been ensured by a novel variable switching frequency double phase shift modulation technique. Experimental results validate the simulation results and show a high efficiency of 98%. A novel and improved 4.5kV SiC Austin SuperMOS half-bridge module with double-sided cooling and ultra-low stray inductance has been developed which can be used to realize a 500kW extreme fast charger. Device characterization tests on the module demonstrate satisfactory static and dynamic performance.Item Optimizing allocation of electric vehicle charging stations in the city of Austin(2017-08) Patel, Akik Bharat; Paterson, Robert G.; McDougall, LindseyIn 2011, the U.S. Presidential Administration set the goal of having a million electric vehicles in the U.S. by 2015. In order to support these goals, the U.S federal government introduced several incentive programs (includes purchasing tax credits) and policies (installing public charging stations) to encourage EV adoption and ease dependence on gasoline consumption. Since the introduction of these policies and mass-marketing of EVs in 2010-11, the sale of commercial electric vehicles in the U.S between 2011 and 2015 has been more than 300,000. However, EVs accounts for less than 1 percent of total light-duty vehicles sales. One of the reasons for the low adoption rate for EV is “range anxiety”. This is created among consumers due to lack of publicly available charging infrastructure and this prohibits users to travel between and within cities. Thus, in order to promote EVs as a primary vehicle for drivers, more charging stations should be made available to the public. The main objective of this research is to identify suitable locations for installing public Electric Vehicle charging stations in the City of Austin. At present, Austin Energy doesn’t have any standard method to identify demand for public charging stations and locate them appropriately to optimize its usage. In order to determine land parcel suitable for installing public charging stations, a set of geo-spatial data were identified from an extensive review of existing literature and similar studies conducted across the globe. These data sets were then edited to form individual raster layers. Each raster data is further classified by assigning scores to each raster value (within a raster layer) based on simple logic. For example, a higher score will be assigned to a raster cell which is closer to a Food establishment and a lower score as we move further away. The higher score basically defines a higher suitability of installing a charging station and vice versa. Further, a map indicating the optimal parcels in the city for installing EV charging infrastructure is created using map algebra which is based on assigning different weighting factors to each raster layer.Item Utility management of plug-in electric vehicle residential charging(2014-05) Hernandez, Guillermo, active 21st century; Baldick, Ross; Webber, Michael E., 1971-The purpose of this study is to identify realistic opportunities and barriers regarding PEV charge management by analyzing real-world PEV data from customers in the Austin Energy service area and evaluating direct, quantifiable economic value benefits as it relates new revenue, cost avoidance, CO2 reductions, and MW potential for peak shaving. The main objective is to provide business analysis to support the strategic road-map for Austin Energy PEV home charging programs. Three main charge program implementations are considered: Uncontrolled Charging, Time of Use Rates, and One Way Utility Control. The data used for the analysis includes 45 households with PEVs from Mueller area; 24 were under a Time of Use trial with pricing incentives to charge at night, and 21 receive normal Austin Energy rates. Data analysis shows that 66% of Time of Use trial group successfully shifted PEV load to Off Peak hours (10:00PM to 6:00AM). The potential of One Way control, based on load availability for interruption, shows that it will not be possible to implement until there are 37,000 PEVs in the Austin Energy area. Uncontrolled Charging represents a risk by increasing load during the residential peak. Time of Use Rates program will incentivize load shifting, reduce wholesale energy costs for Austin Energy while allowing customers to reduce their overall electricity bill.Item Zero to sixty hertz : electrifying the transportation sector and enhancing the reliability of the bulk power system(2015-08) Legatt, Michael Elazar; Baldick, Ross; Webber, Michael EA revolution is underway in the energy sector. Traditional approaches for managing a bulk power system are beginning to give way to a "smart grid" world, in which controllers may have bidirectional communications, with engaged users. At the same time a second transformation has been underway and growing in strength, namely the transition from petroleum as a transportation fuel source towards natural gas for large fleet vehicles, and electricity for consumer vehicles. This thesis focuses primarily on the synergy between the "smart grid" and vehicle electrification transitions. Moving the transportation sector to electricity as a fuel source, at least in Texas, has a myriad of benefits: Charging an electric vehicle without significant growth in renewable or lower-emitting SOFC technologies leads to very significant (80% per mile, 58% per neighborhood) reductions in CO₂ emissions, as well as significant reductions in NO[subscript X] (41% per mile, 17% per neighborhood), PM₁₀ (73% / 62%), PM₂.₅ and UFPM (62% / 55%). SO[subscript X] levels rose by 37%, but could be mitigated with controlled EV charging strategies. Vehicle charging strategies also significantly improved the neighborhood's total emissions profile. Adding in distributed energy resources, microgrid generation and intelligent charging, when optimally allocated, can further reduce these emissions. Vehicle charging schemes that respond dynamically to distributed renewable generation can even be thought of as having zero emissions due to the continual balance of PV generation and EV load on the low side of the distribution transformer. This thesis argues that there may be additionally significant societal benefits by shifting vehicle transportation to electricity, likely far in excess of what could be achieved by controlling power plant emissions alone. Based on an analysis of the ERCOT region, this shift would be expected to produce significant cost reductions for overall energy, improve health (due primarily to the relocation of UFPM far away from major population centers), and lower societal costs. Further gains can be considered as electric vehicles are significantly more energy efficient than their ICE counterparts. Also, on a larger scale, it’s generally easier to reduce emissions from hundreds of fixed power plants than millions of moving ICE vehicles.