The thesis develops a model for deployment of public charging stations for electric vehicles and hybrids in the city of Uppsala in relation to the electricity demand. Areas for deployment of public charging stations has been determined through traffic flow analysis and is displayed in a map over the city of Uppsala. The model was constructed using three different prognoses for an increase of electric vehicles and hybrids. Through the prognoses the electricity demand has been determined and the number of public charging stations in relation to the electricity demand. It could be concluded that future public charging stations is difficult to predict due to uncertainties concerning the future electric vehicle market. In this study it is concluded that the number of public charging stations would not have a significant impact on the total electricity use in the city of Uppsala.

Charging technology is becoming more and more important since rechargeable batteries are commonly used in many applications than ever before. To facilitate various charging profiles, a battery charger with multi-mode is proposed. The charger is composed of an innovative reflex charging circuit and a controllable half-bridge converter with pulse-width-modulation. This multi-mode charger provides not only four basic functions of constant voltage (CV), constant current (CC), pulsed current (PS) and reflex charging (RX), but also the multi-stage charging with hybrid charging modes. The desired charging profile can easily be accomplished by adjusting the controllable parameters of the charger. In order to simplify the control circuit, a digital signal processor (DSP) with the associated sensors and interface circuits are used as the control kernel. By continuously monitoring the charging current and battery voltage, the charging modes can be adapted to the charging strategy. An experimental charging circuit is built and tested. The experiments in this dissertation are carried out on lead-acid batteries, Experimental results show that the charger is able to execute the charging functions of various tentative charging strategies with hybrid charging modes.

A promising method for charging batteries of electric vehicles (EV) is inductive power transfer (IPT), also known as inductive charging. IPT, a convenient, safe, and aesthetic method of charging EVs, inductively transfers high-frequency AC power in the transmitting pad, or coil, to the receiving pad, or coil. However, the application of IPT entails several practical limitations. For example, misalignment of the coils and varied charging distance (air gap) between the coils change the magnetic coupling effect between the transmitting and receiving coils. As a result, system stability decreases because the electrical characteristics in different charging cycles vary. Previous research has rarely proposed an adaptive and effective method to solve the problems of varied coupling. Many EV models, however, exist on the market and more will be released in the future. A universal charger suitable for charging various models of EVs will have broad applications, especially in public charging areas. Therefore, we must design a universal inductive charger capable of providing stable charging voltage to various loads, even with influences by varied magnetic coupling. Also important is the design standard of on-board chargers used for universal inductive charging. The design schemes of the universal inductive charger and on-board chargers can be used as references for the future development of the entire EV inductive charging system.

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Aerosol particulate matter adversely affects the climate, environment and human health. Mechanistic studies have indicated that ultrafine aerosol nanoparticles, those under 100 nm in diameter, may have significant health impacts due to their relatively high number concentration, surface area and potential for deep penetration into the human lung. However, epidemiological evidence remains limited due to the lack of measurement networks that monitor local concentrations of ultrafine particles. Direct ultraviolet (UV) photoionisation electrically charges aerosol nanoparticles for subsequent detection by a mechanism distinct from the ion-particle collisions of conventional methods. The aim of this work is to evaluate photoionisation theory in order to understand and interpret measurements from a low-cost aerosol particle sensor. To accomplish this, theoretical equations are analysed, modelled and compared with experimental results for validation. The photoelectric yield of aerosol particles is explored in terms of particle size, concentration, material, and morphology giving insight into the interaction of light and particles. This thesis introduces the first analysis of photoionisation, recombination, convection/diffusion and transport of particles in an electric field using analytical, numerical, and computational fluid dynamics (CFD) techniques. Characteristic times and dimensionless parameters are defined to determine regimes under which the measurement system is dominated by each of the charging or transport mechanisms. The level of modelling detail required for accurate prediction of aerosol charging and capture methods is demonstrated over a range of conditions. In a continuous flow of aerosol particles, an electric field is applied to capture charge as it is photoemitted from particles and before the emitted charge and particles can recombine. This method yields a novel current measurement directly representative of photoemission. The CFD model agrees well with electrical current measurements demonstrating that the physics of the problem is suitably represented. It is demonstrated that photoemission is linearly proportional to total (mobility) surface area for a large range of sizes and concentrations of particles of self-similar material and morphology, with agglomerated silver particles having 5$\times$ yield of agglomerated carbon from a propane flame. It is shown for the first time that agglomerated particles have a significantly higher photoelectric yield (2.6$\times$) than sintered, close-packed spheres of the same mobility diameter and material, directly contradicting two of the three previous relevant studies. Close-packed spheres have less material exposed to both the photon flux and the particle's surroundings than an agglomerate of the same particle mobility diameter, thereby reducing photoelectric activity. The photoelectrically active area is defined explicitly in this work to reflect the effect of a particle's morphology; the revised definition produces good agreement with experimental results.

Probing Defects and Electronic Processes on Gadolinia-doped Ceria Surfaces Using Electron Stimulated Desorption Haiyan Chen 133 Pages Directed by Professor Thomas M. Orlando Polycrystalline gadolinia-doped ceria (GDC) has been widely investigated as a promising low temperature solid oxide fuel cell (SOFC) electrolyte and as part of composite electrodes. In this thesis, electron stimulated desorption (ESD) has been used to probe the defect related electronic properties of GDC surfaces and the interactions of water and molecular oxygen with these surfaces. In particular, the electron irradiation induced surface charging of GDC has been found to be dependent on the incident electron energy: negative at lower energy and positive at higher energy. Trapping of electrons and holes by the gadolinium aggregated, oxygen vacancy rich grain boundaries has been considered as the origin of surface charging. Depending on the sample treatment, there can be various defects, hydroxyl groups, chemically adsorbed water molecules, or water dimers on GDC surfaces. Water and molecular oxygen interact primarily with defect sites. Systematic investigations of electron stimulated O+ desorption have yielded activation energies relevant to oxygen vacancy production on ceria surfaces, and to surface positive charge dissipation related to ionic conduction of GDC. Highly efficient electron stimulated O+ desorption from GDC surfaces has been attributed to the lowered charge density on oxygen ions coordinated with oxygen vacancy clusters and thus may be used as a probe for surface defect types. Electron stimulated desorption of O2+ from GDC surfaces during molecular oxygen adsorption has shown the ability of ESD to detect chemically adsorbed O2. The velocity distributions of O2+ can be used to probe intermediate adsorption species such as O2, as well as the positive charge of the surface. Overall, this thesis has demonstrated that ESD can provide important information on the kinetics and dynamics of surface charging, charge transport, adsorption and reactions occurring at defective insulating metal oxides materials. The abilities to probe the defects and their roles in surface processes make ESD a valuable technique for surface chemistry and catalysis studies.

M.Ing. / Steel products can be produced by either following the blast furnace with oxygen steel making route or the electric arc steel making route. The blast furnace with oxygen route requires liquid iron to produce steel and the electric arc route requires scrap metal as a major input. This in essence implies that for the blast furnace route if no liquid iron is produced, no steel products will be produced and similarly so for the electric arc route. ArcelorMittal Vanderbijlpark Works produces its liquid iron from two furnaces namely blast furnace C and blast furnace D. However the reliability of these furnaces is in question as their daily operations are plagued with random failures of equipment and machinery. The main consequence of these failures is the unavailability of the furnaces to produce liquid iron. This is undesirable from a business perspective due to the inherent production losses, loss of potential earnings as well as the high costs incurred to restore the furnaces back into operation.This research dissertation will focus on the operation of these blast furnaces. The fundamental success criteria for this research document will be to identify opportunities to improve the reliable operation of these furnaces. The scope of the work will however be limited to blast furnace C and particularly at improving its charging system’s availability. The availability of the charging system can be improved by knowing what type of failures to expect and how to mitigate their effects. A starting point would then be to examine past failure data. Thus data from 2008 has been collected and analyzed making use of statistical methods, design analysis methods and research methodologies. The results suggest that the availability of the system has a direct correlation between its reliability and maintainability. The results obtained were then subjected to a risk analysis to identify measures that could be employed to improve the charging system’s availability.

The inevitable choice for the automotive industry to suppress greenhouse gas emissions is zero-emission vehicles such as battery electric vehicles. Some of the main barriers regarding the adoption of electric vehicles are range anxiety, and lack of charging infrastructure, which can be addressed by ultra-fast chargers or charging stations. The conventional ultra-fast chargers are low-voltage (LV) connected through line-frequency transformers, which pose disadvantages such as low efficiency, high cost, and large footprints. The medium-voltage (MV) connected charging station is proposed by the researchers to overcome the challenges regarding the conventional chargers by eliminating the line-frequency transformer and direct connection to the medium voltage. The most challenging part of the medium-voltage ultra-fast chargers is the AC/DC stage connection to the medium voltage. Different medium-voltage multilevel converters have been proposed to facilitate the direct connection to the medium-voltage grid. However, disadvantages such as a high number of components and control complexity weaken the strength of medium-voltage connected stations. The main focus of this thesis is on novel advanced medium-voltage multilevel topologies and control techniques for medium-voltage connected ultra-fast EV charging applications. First, a novel controller based on SPWM is proposed to control the flying capacitor voltages of a four-level T-type Nested Neutral Point Clamped (NNPC) topology. Second, a new five-level T-type NNPC topology is proposed that has a minimum number of components in comparison to other existing five-level topologies. To extend the voltage and power rating, a novel seven-level topology is proposed that has the lowest number of components in comparison to other existing topologies. Moreover, three different controllers are developed to control the voltages of the seven-level topology based on Model Predictive Control, where the challenges regarding significant computational burden and weighting factor elimination are addressed. Finally, an MV-connected ultra-fast charging station architecture is proposed, where the proposed seven-level topology is considered as the AC/DC stage. Comparison of the proposed topology to the LV-connected stations shows that the efficiency, cost, and power quality of the charging stations can be improved significantly. / Thesis / Doctor of Philosophy (PhD)

Uptake of electric vehicles (EVs) is accelerating as governments around the world aim to decarbonize transportation. While EV adoption is widely promoted in Canada, swift and widespread EV adoption will require some degree of controlled charging to mitigate the challenges that EV charging imposes onto the power system, such as increased cost and emissions from electricity generation. In this analysis, the potential benefits of utility controlled charging (UCC) are evaluated for the city of Regina, Saskatchewan, which aims to be 100% renewable by 2050. The flexibility that UCC can contribute, and its effectiveness for integrating variable renewables is tested in configurations with solar resources, wind resources, and a mix of both. A novel modelling methodology is developed to do so, which links a travel demand model (TASHA) and an electricity system production cost model (SILVER), using a novel intermediate charging model to simulate electric vehicle travel behaviour and utility controlled charging. The use of operational models allows for an accurate representation of both travel demand and electricity system operating costs and emissions at a high spatial and temporal resolution. By linking sectoral models in this way, the interactions between the two sectors - transportation and power – can be investigated simultaneously with detailed insight into the two individual sectors. Results show that uncontrolled charging will increase average emissions from the electricity grid, but controlled charging decreases both greenhouse gas emissions as well as operating costs. By shifting vehicle charging to times when renewable energy production is high, UCC reduces operating costs and emissions by 7% compared to uncontrolled charging, without requiring changes to travel scheduling and behaviour. The temporal characteristics of wind generation is found to be more compatible with controlled charging than solar PV, due to its longer generation periods and higher capacity factor in the winter, when demand is also high. / Graduate / 2022-11-19

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