Dissertations / Theses on the topic 'Hybrid electric cars'

With the increasing rate of pollution from transports with fossil fuel, greater active action is required in the form of many measures from the global community to reduce the use of diesel and gasoline driven vehicles. The purpose of the study was to examine the public awareness and attitudes towards electric driven vehicles, as well as the factors important to the public when purchasing such vehicles. At the same time, a survey was carried out to identify possible differences in attitude between individuals who had electric driven vehicles and those who had gasoline or diesel driven cars. Finally, the government subsidies were examined in order to evaluate whether they affect the public willingness to buy electric driven vehicles. The survey was conducted in Sweden and was based partially on a poll and partially on interviews. The result of this study showed that there is a great interest for the general public towards electric driven vehicles, and the majority who took part in the survey was aware of the positive effects of electric driven vehicles. The comparison between the two groups showed that there is a significant difference between the attitudes to the electric vehicles. Among other things, there are differences regarding the electric vehicles' future in Sweden and also differences in the attitude to the price of the electric vehicle. However, there is no difference between the attitudes of the two groups regarding environmental friendliness and the importance of the state subsidy.

Today, the contribution of the transportation sector on greenhouse gases is evident. The fast consumption of fossil fuels and its impact on the environment has given a strong impetus to the development of vehicles with better fuel economy. Hybrid electric vehicles fit into this context with different targets, starting from the reduction of emissions and fuel consumption, but also for performance and comfort enhancement. Vehicles exist with various missions; super sport cars usually aim to reach peak performance and to guarantee a great driving experience to the driver, but great attention must also be paid to fuel consumption. According to the vehicle mission, hybrid vehicles can differ in the powertrain configuration and the choice of the energy storage system. Lamborghini has recently invested in the development of hybrid super sport cars, due to performance and comfort reasons, with the possibility to reduce fuel consumption. This research activity has been conducted as a joint collaboration between the University of Bologna and the sportscar manufacturer, to analyze the impact of innovative energy storage solutions on the hybrid vehicle performance. Capacitors have been studied and modeled to analyze the pros and cons of such solution with respect to batteries. To this aim, a full simulation environment has been developed and validated to provide a concept design tool capable of precise results and able to foresee the longitudinal performance on regulated emission cycles and real driving conditions, with a focus on fuel consumption. In addition, the target of the research activity is to deepen the study of hybrid electric super sports cars in the concept development phase, focusing on defining the control strategies and the energy storage system’s technology that best suits the needs of the vehicles. This dissertation covers the key steps that have been carried out in the research project.

This thesis (1) reports a new Dynamic Programming (DP) approach, and (2) reports a Real Time Control strategy to optimize the energy management of a Hybrid Electric Vehicle(HEV). Increasing environmental concerns and rise in fuel prices in recent years has escalated interest in fuel efficient vehicles from government, consumers and car manufacturers. Due to this, Hybrid electric vehicles (HEV) have gained popularity in recent years. HEV’s have two degrees of freedom for energy flow controls, and hence the performance of a HEV is strongly dependent on the control of the power split between thermal and electrical power sources. In this thesis backward-looking and forward-looking control strategies for two HEV architectures namely series and parallel HEV are developed. The new DP approach, in which the state variable is not discretized, is first introduced and a theoretical base is established. We then prove that the proposed DP produces globally optimal solution for a class of discrete systems. Then it is applied to optimize the fuel economy of HEV's. Simulations for the parallel and series HEV are then performed for multiple drive cycles and the improved fuel economy obtained by the new DP is compared to existing DP approaches. The results are then studied in detail and further improvements are suggested. A new Real Time Control Strategy (RTCS) based on the concept of preview control for online implementation is also developed in this thesis. It is then compared to an existing Equivalent Cost Minimization Strategy (ECMS) which does not require data to be known apriori. The improved fuel economy results of the RTCS for the series and parallel HEV are obtained for standard drive cycles and compared with the ECMS results

I Sverige används det idag cirka 5,4% förnybara drivmedel inom transportsektorn, att jämföra med under 0,5% år 2000. Av de ickefossila drivmedlen är el något som ofta benämns som en permanent och realistisk framtida lösning. Visionen ”Stockholm – Elbilsstad 2030” drivs av Stockholms Stad i samarbete med Fortum AB i syfte att ersätta den fossilbränsleslukande fordonsflottan. I den här studien undersöks de tekniska förutsättningarna och de eventuella vinsterna av ett storskaligt införande av elbilar. Studien har gjorts genom en modellering där parametrar som elbilens prestanda, elpris, bilens inköpspris och totala utsläpp använts. Resultatet skall presentera ett mikro- och ett makroresultat. Vinsterna beräknas dels för den enskilde individen, men också för samhället i stort. Vinsterna beräknas med en känslighetsanalys baserad på reella framtida scenarier. Resultaten visar tydligt att för den genomsnittlige Stockholmaren är elbilen det mest ekonomiskt lönsamma valet på sikt. På tio års sikt beräknas bensinbilen kosta individen 65,93% mer än elbilen om bensinpriset fortsätter med samma utveckling. En känslighetsanalys visar att även om bensinpriset skulle sjunka med 5% årligen in i framtiden skulle bensinbilen ändå vara 31,3% dyrare på tio års sikt. Resultaten visar också att samhällets kostnader för bilflottans utsläpp förväntas sjunka med 98% eller 92% beroende på om den svenska elproduktionen är tillräcklig eller om man måste importera el från övriga Norden. Samtidigt som kostnaderna för utsläppen sjunker för samhället, sjunker även skatteintäkterna till följd av minskad bensinanvändning. Om elpriset på sikt skulle stiga till följd av en ökad användning skulle detta dock kunna leda till att förlusten reduceras. Klart är att storskaligt införande av elbilar kräver ett engagemang från staten där den ekonomiska förlusten får ses som en investering i miljön och framtiden.
In Sweden there are currently about 5.4% renewable fuel vehicles within the transport sector, compared to less than 0.5% in 2000. Amongst the non-fossil fuel alternatives electricity is something which has often been referred to as a permanent and realistic future solution. The vision “Stockholm – A City of Electric Cars in 2030" is run by the City of Stockholm in cooperation with Fortum AB in order to replace the fossil-fuel-guzzling fleet. This report examines the technical conditions and possible gains of a large scale introduction of electric cars. The study was conducted through a modelling in which parameters such as electric car performance, tariff and total emissions are used. The conclusion will reveal a micro- and macro result. Economic gains are calculated both for the individual, but also for society at large. The profits are calculated by a sensitivity analysis based on realistic future scenarios. The results clearly show that for the average Stockholm resident, the electric car is the most economical choice. In ten years time the gasoline car is expected to cost the individual 65.93% more than the electrical car based on that the price of gasoline continues its current growth. A sensitivity analysis shows that even if gasoline prices were to drop by 5% annually into the future, gasoline car would still be 31.3% more expensive than the electric car in ten years time. The results also show that the societal costs of the car fleet’s emissions are expected to fall by 98% or 92% depending on whether the Swedish electricity production is sufficient, or whether imported electricity from other Nordic countries is necessary. While the cost of emissions decreases for the society, so are tax revenues due to reduced gasoline use. However, if the electricity price in the long run would rise due to increased use, this could however lead to a reduction of the loss. It is clear that for a large-scale introduction of electric cars to be successful it requires a committed government which will have to see the economic loss as a means to investment in the future and the environment.

This thesis (1) reports the development of simulation tools and control strategies for optimizing hybrid electric vehicle (HEV) energy management, and (2) reports the design and testing of a hydraulic hybrid school bus (HHB) prototype. A hybrid vehicle is one that combines two or more energy sources for use in vehicle propulsion. Hybrid electric vehicles have become popular in the consumer market due to their greatly improved fuel economy over conventional vehicles. The control strategy of an HEV has a paramount effect on its fuel economy performance. In this thesis, backward-looking and forward-looking simulations of three HEV architectures (parallel, power-split and 2-mode power-split) are developed. The Equivalent Cost Minimization Strategy (ECMS), which weights electrical power as an equivalent fuel usage, is then studied in great detail and improvements are suggested. Specifically, the robustness of an ECMS controller is improved by linking the equivalence factor to dynamic programming and then further tailoring its functional form. High-fidelity vehicle simulations over multiple drive-cycles are performed to measure the improved performance of the new ECMS controller, and to show its potential for online application. While HEVs are prominent in the consumer market and studied extensively in current literature, hydraulic hybrid vehicles (HHVs) only exist as heavy utility vehicle prototypes. The second half of this thesis reports design, construction, and testing of a hydraulic hybrid school bus prototype. Design considerations, simulation results, and preliminary testing results are reported, which indicate the strong potential for hydraulic hybrids to improve fuel economy in the school bus vehicle segment.

Dans un contexte ou la question de la préservation de l'environnement est devenue un sujet sociétal majeur, la recherche de nouvelles technologies pour remplacer la voiture à essence constitue un véritable enjeu industriel. Les véhicules hybrides et électriques sont une alternative prometteuse aux véhicules conventionnels. Ce travail de thèse porte sur la conception et l'optimisation des machines électriques pour la motorisation de ces voitures.Au cours de ces travaux, nous avons développé une nouvelle méthodologie de dimensionnement et d'optimisation des machines synchrones à double excitation. L'intérêt de cette méthode est son bon compromis entre la précision et le temps de calcul et sa capacité d'adaptation à plusieurs types de machines. Le second volet de la thèse est consacré à la proposition d'une nouvelle structure de machine synchrone à rotor bobiné. Une technique originale de compensation de la réaction magnétique d'induit est mise en place, elle consiste en l'insertion d'aimants secondaires permettant de créer un flux dans l'axe q de la machine. Ce dernier a pour rôle d'affaiblir le flux de la réaction magnétique d'induit
In a context where the question of the environmental protection has become a major social problem, research new technologies to replace the gasoline car is a real industrial challenge. The hybrid and electric vehicles are a promising alternative to conventional vehicles. This thesis focuses on the design and optimization of electrical machines for electric and hybrid cars.In this work, we developed a new methodology for design and optimization of hybrid excitation synchronous machines. The advantage of this method is its good compromise between accuracy and computation time and its ability to be adapted to a wide range of machines. The second part of this thesis is devoted to the development of a new structure of a wound rotor synchronous machine. A novel technique for compensating the armature reaction of this machine is introduced, it involves the insertion of secondary magnets to produce a quadratic axis flux (q-axis), this latter has the function of weakening the armature reaction flux

This thesis develops dynamic models for the two-mode FWD EVT, develops a control system based on those models that is capable of meeting driver torque demands and performing synchronous mode shifts between different EVT modes while also accommodating preferred engine operating points. The two-input two-output transmission controller proposed herein incorporates motor-generator dynamics, is based on a general state-space integral control structure, and has feedback gains determined using linear quadratic regulator (LQR) optimization. Dynamic modeling of the vehicle is categorized as dynamic modeling of the mechanical and electrical subsystems where the mechanical subsystem consists of the planetary gear sets, the transmission and the engine whereas the electrical subsystem consists of the motor-generator units and the battery pack. A discussion of load torque is also considered as part of the mechanical subsystem. With the help of these derived dynamic models, a distinction is made between dynamic output torque and steady-state output torque. The overall control system consisting of multiple subsystems such as the human driver, power management unit (PMU), friction brakes, combustion engine, transmission control unit (TCU) and motor-generator units is designed. The logic for synchronous mode shifts between different EVT modes is also detailed as part of the control system design. Finally, the thesis presents results for responses in individual operating modes, EVT mode shifting and a full UDDS drive cycle simulation.

In this work, the possible benefits and drawbacks of 48 Volt E/E systems in MotorSport will be analyzed. MotorSport has always been a lauchpad for new technologies, and in recent years the necessity to increase the electrical power on cars has become a key study topic. Increasing the voltage level is one possible solution to mitigate the downsides of increased power. In this dissertation the technologies currently available on the market will be analyzed, with a focus on 48 Volt systems that are already deployed on hybrid vehicles. Subsequently, a real racing car E/E architecture will be analyzed and the impact of an installation of a 48 Volt system will be evaluated. There follows a discussion on vehicle power supply technologies that are already available and the challenges of the supply systems for the future, ending with a set of simulations and considerations about the power supply system of the car under evaluation.

This study examines the potential of electrification in reducing greenhouse gas emissions and air pollution from passenger cars in a short- to mid-term time perspective. Using Stockholm County as a case study, this has been done in a three-step process by modeling the relative change in emissions between 2019 and 2030. Firstly, four scenarios have been created for 2030, each of which state the number of gasoline cars, diesel cars, PHEVs and EVs in use on a municipality-level. Secondly, for each scenario, the movement of traffic has been modeled on a car-by-car basis using the Scaper/MATSim transportation model at KTH. Thirdly, using emission factors from HBEFA, an emission model for 17 pollutants has been created for the modeling of hot emissions, cold start emissions, evaporation losses and non-exhaust emissions. Compared to 2019 emission levels, with EVs and PHEVs accounting for 64.5 % of the car fleet, the optimistic scenarios suggest that emissions of CO2, NMHC and NOx could decrease by up to 43.6, 63.5 and 84.7 %, respectively, by 2030. Besides electrification, for NMHC and NOx, these emission reductions are largely a result of technological improvements of combustion vehicles. Conversely, emissions of particulate matter (PM10 and PM2.5) are projected to increase by up to 45.6 % in the optimistic scenarios. Roughly corresponding to the increase in the total driving distance, this increase can be attributed to the lower cost of driving of electric cars and the projected population increase of 15.5 %.

The road transport sector is heavily dependent on fossil-fuel based technologies, and as a result, contribute a significant share towards climate change and other environmental problems. If the transport sector is to reduce its adverse impacts on climate change, then it requires a global shift towards low-carbon technologies. However, deploying these new technologies brings uncertainties regarding their environmental profile, hence, the need for applying a life cycle approach in evaluating their potential environmental impacts. This thesis aim to evaluate the potential life-cycle environmental impacts associated with travelling 1 km in a battery electric cars (BEV) and plug-in hybrid electric cars (PHEV) operated in the EU at present-day, and in the future up till 2050. The study applied the life cycle assessment (LCA) and ReCiPe Midpoint (H) methodologies to assess and calculate the potential life cycle environmental impacts of all vehicle scenarios. The datasets of the vehicles have been modelled with a modular approach by linking together various vehicle components. The future time perspective based on two future scenarios; the Mod-RES, representing the reference future scenario and the High-RES representing a future ambitious policy scenario.   The EU28 electricity production based on Fichtner, et al. was used to model the use phase all vehicle scenarios. The result showed BEV performed best in indicators for global warming (GWP), ozone depletion and fossil resource scarcity. The thesis best estimate for GWP is 5.61E-2 kgCO2 eq resulting from the BEV_High-RES scenario; representing a decrease in GWP of around 80% and 69% when compared to the ICEV and the baseline BEV respectively. On the other hand, the baseline BEV performed worst in impact categories related to human toxicity and damage to ecosystems; the conventional gasoline car showed the lowest estimate for indicators on human toxicity, acidification and eutrophication as defined in the baseline scenario. Nonetheless, the future scenarios showed promising results for all technologies; as projections for stringent environmental regulations, ‘cleaner’ energy systems and continuous advancement in vehicle technologies offered a significant reduction in all impact categories. Notably, the BEV reduced its impact on toxicity categories to around 38% of the initial values for the baseline scanario. Results are strongly dependent on assumptions regarding the vehicle and battery lifetime, the use phase electricity source and the vehicle consumption.  The findings establish the significance of carrying out a full LCA, including future time perspective and assessing impact categories beyond climate change. Also, it underlined the suggestion that production of electric cars raised more concern for EVs than conventional cars; thus, the tendency for environmental problem-shifting and the need for policy-makers to recognise existing trade-offs.
Vägtransportsektorn är starkt beroende av fossilbränslebaserad teknik och bidrar därmed till en betydande andel av klimatförändringen och andra miljöproblem. Om transportsektorn ska minska dess negativa inverkan på klimatförändringen, krävs det en global övergång till teknik med låga koldioxidutsläpp. Utnyttjandet av denna nya teknik medför dock osäkerhet om sin miljöprofil och därmed behovet av att tillämpa ett livscykelperspektiv vid utvärderingen av deras potentiella miljöpåverkan. Avhandlingen presenterar en livscykelanalys av nuvarande och framtida elfordon. Fokus ligger på batteri elbilar (BEV) och plug-in hybrid elbilar (PHEV) som drivs i EU. EU28-elproduktionen baserad på Fichtner, et al. användes för att beräkna de potentiella livscykelmiljöeffekterna av alla fordonsscenarier baserade på effektkategorier definierade i ReCiPe Midpoint (H) -metoden. Resultatet visade att BEV fungerade bäst i indikatorer för global uppvärmning (GWP), ozonförlust och fossila resurserbrist. Avhandlingens bästa uppskattning för GWP är 5,61E-2 kgCO2 ekv som härrör från BEV_High-RES-scenariot; vilket motsvarar en minskning av GWP på cirka 80% och 69% jämfört med ICEV respektive baseline BEV. Å andra sidan har baslinjens BEV den högsta andelen miljöindikatorer relaterade till human toxicitet och skador på ekosystemen. Den konventionella bensinbilen visade den lägsta uppskattningen av indikatorer för human toxicitet, försurning och eutrofiering enligt definitionen i baslinjen. De framtida scenarierna visade emellertid lovande resultat för all teknik, detta förutsätter strängre miljöregler, "renare" energisystem och kontinuerlig framsteg inom fordonsteknik som kommer att erbjuda en betydande minskning av alla påverkningskategorier. I synnerhet reducerade BEV: s påverkan på toxicitetskategorier till omkring 38% av de ursprungliga värdena för baslinjens scanario. Resultaten är starkt beroende av antaganden om fordonets och batteritiden, användningsfasens elkälla och fordonsförbrukningen. Resultaten visar betydelsen av att utföra en fullständig LCA, inklusive framtida tidsperspektiv och bedömning av påverkningskategorier utanför klimatförändringen. Det understryker också förslaget gällamde produktion av elbilar har en betydande ökade oro för elektriska motorer än konventionella bilar. Det finns en risk för miljöproblemförskjutning och ett behovet av att politiska beslutsfattare erkänner befintliga avvägningar.
REFLEX - Analysis of the European energy system under the aspects of flexibility and technological progress

In recent years lithium-ion battery electric vehicles and stored hydrogen electric vehicles have been developed to address the ever-present threat of climate change and global warming. These technologies have failed to achieve profitability at costs consumers are willing to bear when purchasing a vehicle. IFBattery, Inc. has developed a unique primary battery chemistry which simultaneously produces both electricity and hydrogen-on-demand while being both low cost and without carbon emissions. In order to determine the feasibility of the IFBattery chemistry for mobile applications, a prototype golf cart was constructed as the first public application of IFBattery technology. The legacy lead acid batteries of the prototype golf cart were replaced with an IFBattery chemistry tuned to primarily produce hydrogen-on-demand with supplemental electricity. Hydrogen produced by the IFBattery was purified and then fed into a hydrogen fuel cell where electricity was produced to power the vehicle. Electricity from the IFBattery was converted to the common voltage of the golf cart and also used to power the vehicle. Validation testing of the IFBattery powered golf cart demonstrated favorable results as an alternative to both lithium-ion battery and stored hydrogen technologies, and displayed potential for future applications.

Mestrado em Energia Renováveis e Eficiência Energética
The development of multi sources systems for the production of energy is more and more considered and the interest in it increases day after day. These systems may ensure the production of energy needed and reduce the cost of energy production while taking into account the environment and reducing emissions. The aim of this thesis is the study of multi sources systems with the design and development of a multi-source cell selection system to control various sources of renewable and non-renewable energy, Due to the different characteristics of each energy source, the best solution remains to rely on all these sources at the same time. We proposed to use an Arduino mega board with an electronic card, which we will show the stages of its development, that manages the power transfer to the load according to the required energy.
O desenvolvimento de sistemas de fontes múltiplas para a produção de energia é cada vez mais considerado e o seu interesse aumenta dia após dia. Estes sistemas podem garantir a produção de energia necessária e reduzir o seu custo, levando em consideração o meio ambiente e reduzindo as emissões. O objetivo desta tese consiste no estudo de sistemas de fontes múltiplas com a concepção e desenvolvimento de um sistema de seleção e controlo de várias fontes de energia renováveis e não renováveis. Devido às diferentes características de cada fonte de energia, a melhor solução será selecionada de todas essas fontes simultâneamente. É proposto usar um Arduino mega e uma placa de circuito impresso, onde serão mostradas as etapas de seu desenvolvimento, que gere a transferência de potência para a carga de acordo com a energia necessária.