Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 130-131). Also available on the World Wide Web.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed October 25, 2007) Includes bibliographical references (p. 61-62).

In this thesis, several design methodologies are presented to improve the reliability of dual traction inverters in hybrid electric vehicles (HEVs). Several power inverter topologies including the two-level voltage-source inverter, the boost voltage-source inverter, the Z-source inverter, and reduced-parts inverters are compared in terms of power ratings, volume, and efficiency. The comparison results show that the two-level voltage-source inverter presents higher efficiency, higher power density, and lower cost. Therefore, the back-to-back two-level voltage-source inverter is selected. DC-link capacitor and power modules are the most vulnerable components in dual traction inverters. The lifetime of capacitor is mainly determined by the core temperature. In this thesis, an interleaving control scheme is proposed to reduce the capacitor power loss by decreasing the total DC-link current harmonics. With reduced capacitor power loss, the core temperature of capacitor is reduced. Therefore, the lifetime of capacitor is improved. In addition, a fast electro-thermal model of traction inverters is proposed to estimate the junction temperatures of power devices. Practical switching losses are measured and thermal coupling effects between multiple devices are considered. The calculation rate of junction temperature is reduced by considering both power loss profiles and properties of the thermal impedance. With this model, over-temperature protection and lifetime evaluation can be implemented to enhance the reliability of traction inverters. Finally, a current sensor fault-tolerant operation scheme with six-phase current reconstruction technique is proposed to improve the reliability of dual inverters. In order to get the missing phase currents, the PWM signals are phase shifted to create the reconstruction conditions. With measured DC-link current, all phase-currents of dual inverters are obtained at the expense of slight degradation of maximum allowable modulation index. Therefore, when some or all of the phase current sensors are failed, the dual traction inverters can operate normally. / Thesis / Doctor of Philosophy (PhD)

There has been an increased necessity to search for alternative transportation methods, mainly driven by limited fuel availability and the negative impacts of climate change and exhaust emissions. These factors have lead to increased regulations and a societal shift towards a cleaner and more e cient transportation system. Automotive and technology companies need to be looking for ways to reshape mobility, enhance safety, increase accessibility, and eliminate the ine ciencies of the current transportation system in order to address such a shift. Hybrid vehicles are a popular solution that address many of these goals. In order to fully realize the bene ts of hybrid vehicle technology, the power distribution decision needs to be optimized. In the past, global optimization techniques have been dismissed because they require knowledge of the journey of the vehicle in advance, and are generally computationally extensive. Recent advancements in technologies, like sensors, cameras, lidar, GPS, Internet of Things, and computing processors, have changed the basic assumptions that were made during the vehicle design process. In particular, it is becoming increasingly possible to know future driving conditions. In addition to this, autonomous vehicle technology is addressing many safety and e ciency concerns. This thesis considers and integrates recent technologies when de ning a new approach to hybrid vehicle supervisory controller design and optimization. The dynamic programming algorithm has been systematically applied to an autonomous vehicle with a power-split hybrid electric powertrain. First, a more realistic driving cycle, the Journey Mapping cycle, is introduced to test the performance of the proposed control strategy under more appropriate conditions. Techniques such as vectorization and partitioning are applied to improve the computational e ciency of the dynamic programming algorithm, as it is applied to the hybrid vehicle energy management problem. The dynamic programming control algorithm is benchmarked against rule-based algorithms to substantively measure its bene ts. It is proven that the DP solution improves vehicle performance by at least 9 to 17% when simulated over standard drive cycles. In addition, the dynamic programming solution improves vehicle performance by at least 32 to 39% when simulated over more realistic conditions. The results emphasize the bene ts of optimal hybrid supervisory control and the need to design and test vehicles over realistic driving conditions. Finally, the dynamic programming solution is applied to the process of adaptive control calibration. The particle swarm optimization algorithm is used to calibrate control variables to match an existing controller's operation to the dynamic programming solution. / Thesis / Master of Applied Science (MASc)

EcoRouting refers to the determination of a route that minimizes vehicle energy consumption compared to traditional routing methods, which usually attempt to minimize travel time. EcoRoutes typically increase travel time and in some cases this increase is constrained for a viable route. While significant research on EcoRouting exists for conventional vehicles, incorporating the novel aspects of plug-in hybrids opens new areas to be explored. A prototype EcoRouting system has been developed on the MATLAB platform that takes in map information and converts it to a graph of nodes containing route information such as speed and grade. Various routes between the origin and destination of the vehicle are selected and the total energy consumption and travel time for each route are estimated using a vehicle model. The route with the minimum energy consumption will be selected as the EcoRoute unless there is a significant difference between the minimum time route and the EcoRoute. In this case, selecting a sub-optimal route as the EcoRoute will increase the probability that the driver uses a lower fuel consumption route. EcoRouting has the potential to increase the fuel efficiency for powertrains designed mainly for performance, and we examine the sensitivity of the increased efficiency to various vehicle and terrain features. The reduction in energy consumption can be achieved independent of powertrain modifications and can be scaled using publicly available parameters. / Master of Science

EPA testing methods for calculation of fuel economy label ratings, which were revised beginning in 2008, use equations that weight the contributions of fuel consumption results from multiple dynamometer tests to synthesize city and highway estimates that reflect average U.S. driving patterns. The equations incorporate effects with varying weightings into the final fuel consumption, which are explained in this thesis paper, including illustrations from testing. Some of the test results used in the computation come from individual phases within the certification driving cycles. This methodology causes additional complexities for hybrid electric vehicles, because although they are required to have charge-balanced batteries over the course of a full drive cycle, they may have net charge or discharge within the individual phases. The fundamentals of studying battery charge-balance are discussed in this paper, followed by a detailed investigation of the implications of per-phase charge correction that was undertaken through testing of a 2010 Toyota Prius at Argonne National Laboratory's vehicle dynamometer test facility. Using the charge-correction curves obtained through testing shows that phase fuel economy can be significantly skewed by natural charge imbalance, although the end effect on the fuel economy label is not as large. Finally, the characteristics of the current 5-cycle fuel economy testing method are compared to previous methods through a vehicle simulation study which shows that the magnitude of impact from mass and aerodynamic parameters vary between labeling methods and vehicle types. / Master of Science

The purpose of this study was to determine Chinese and U.S. consumers' attitudes and perceptions toward hybrid cars and the likelihood of purchasing one in the future.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Lithium-ion batteries are today finding use in automobiles aiming at reducing fuel consumption and emissions within transportation. The requirements on batteries used in vehicles are high regarding performance and lifetime, and a better understanding of the interior processes that dictate energy and power capabilities is a key to strategic development. This thesis concerns aging in lithium-ion cells using electrochemical tools to characterize electrode and electrolyte properties that affect performance and performance loss in the cells.   A central difficulty regarding battery aging is to manage the coupled effects of temperature and cycling conditions on the various degradation processes that determine the lifetime of a cell. In this thesis, post-mortem analyses on harvested electrode samples from small pouch cells and larger cylindrical cells aged under different conditions form the basis of aging evaluation. The characterization is focused on electrochemical impedance spectroscopy (EIS) measurements and physics-based EIS modeling supported by several material characterization techniques to investigate degradation in terms of properties that directly affect performance. The results suggest that increased temperature alter electrode degradation and limitations relate in several cases to electrolyte transport. Variations in electrode properties sampled from different locations in the cylindrical cells show that temperature and current distributions from cycling cause uneven material utilization and aging, in several dimensions. The correlation between cell performance and localized utilization/degradation is an important aspect in meeting the challenges of battery aging in vehicle applications.   The use of in-situ nuclear magnetic resonance (NMR) imaging to directly capture the development of concentration gradients in a battery electrolyte during operation is successfully demonstrated. The salt diffusion coefficient and transport number for a sample electrolyte are obtained from Li+ concentration profiles using a physics-based mass-transport model. The method allows visualization of performance limitations and can be a useful tool in the study of electrochemical systems. / <p>QC 20140512</p>

La propulsion hybride (thermique-électrique) constitue une solution pertinente dans la conception de véhicules consommant moins de 2 litres de carburant / 100 km. Néanmoins, ce type de motorisation se heurte à des niveaux de coûts trop élevés pour une large diffusion. Une des raisons de ces coûts importants se situe au niveau des aimants permanents de type terre-rare intégrant la constitution de la machine électrique, et dont le cours des prix est très instable, rendant ce type de machine difficilement compatible avec le marché visé. L'objectif de cette thèse est d’investiguer les structures de machines électriques sans aimant terre-rare et dont les performances massiques peuvent rester comparables à celles des machines à aimants permanents. La première partie des travaux correspond à une vaste étude bibliographique sur les différentes technologies de machines électriques, les différentes architectures et topologies existantes, les matériaux innovants et enfin les techniques et méthode d’analyse et d’optimisation. A la fin de cette phase, il est fait le choix d’étudier les machines synchro-réluctantes à barrières de flux. L’accent est alors mis sur le design de la géométrie du rotor, mais également sur l’impact des matériaux utilisés (matériaux magnétiques classiques ou innovants) sur les performances. La seconde partie de la thèse a pour objectif de mettre en œuvre une stratégie efficace afin de dimensionner de manière optimale l’architecture de la machine choisie. Le choix est fait d’aborder le problème de manière séquentielle : en premier lieu, une optimisation de la topologie seule en s’affranchissant de l’impact de la commande ; dans un deuxième temps, une optimisation de la commande de la géométrie optimisée avec tracé des cartographies de performances ; enfin, une évaluation des différents matériaux au travers de la comparaison de ces performances. Trois configurations de machines sont dimensionnées : une machine synchro-réluctante classique à air (SyRC), une machine synchro-réluctante assistée de d’aimants permanents de type ferrites (SyRA) et enfin une machine synchro-réluctante utilisant le matériau dit « Dual Phase » (SyRDP). Celui-ci présente théoriquement la caractéristique de pourvoir changer localement ses propriétés magnétiques (passage des propriétés magnétiques d’un acier vers celles amagnétiques de l’air dans le cas limite idéal) grâce à un traitement thermique particulier, tout en conservant ses propriétés mécaniques. Cette étude permet de conclure que la machine synchro-réluctante assistée de ferrites montre les meilleures aptitudes, tant pour ce qui est de la puissance crête que du défluxage potentiel. Cependant, la machine synchro-réluctante dans cette configuration est sur le plan mécanique plus fragile que la SyRC et la SyRDP. En effet, avec l’ajout des ferrites, les ponts fer (magnétiques) permettant d’assurer l’intégrité mécanique du rotor à vitesse élevée sont d’autant plus sollicités. En phase de conception, l’optimisation électromagnétique tend à les réduire car ce sont des courts-circuits magnétiques entrainant une réduction des performances, alors que les considérations mécaniques tendent plutôt à augmenter leur épaisseur. La troisième partie de cette thèse porte sur la prise en compte des contraintes mécaniques lors du dimensionnement électromagnétique du rotor. Etant donné que la modélisation et l’optimisation électromagnétiques sont basées sur des modèles éléments finis, et afin de ne pas alourdir davantage le dimensionnement, il est décidé de mettre en place un modèle analytique des contraintes mécaniques particulièrement critiques dans les ponts magnétiques. Les équations de calcul sont inspirées de la théorie des poutres et le modèle est recalibré grâce à des simulations éléments finis. / Hybrid propulsion (electric thermal) is a relevant solution in the search for vehicles consuming less than 2 liters of fuel / 100 km. Nevertheless, this type of motorization comes up against cost levels that are too high for widespread distribution. One of the reasons for these high costs is the level of permanent magnets integrating the constitution of the electric machine. In addition, the "material cost" of these permanent magnets has soared in recent years making this type of machine difficult to match the target market. The aim of the thesis is to propose a magnetless electrical machine structure whose mass performances are comparable to those of permanent magnet machines. This increase in performance can be achieved by high rotation speeds or thermal sizing different from those usually used. The works proposed as part of this thesis will be as follows: - In-depth bibliographic analysis to propose a structure and a principle most adapted to the envisaged constraints- Proposal of a multi physical model (magnetic, thermal, mechanical) of the selected structure. - Use of the multi-physical model for optimal sizing- Follow-up of the realization of the prototype - Experimental validation of the prototype. This work will be conducted as part of a consortium integrating academics, manufacturers and automotive suppliers of the highest order.