Li-ion batteries have become one of the chosen energy storage devices that are used in applications such as power tools, cellular phones and electric vehicles (EV). With the demand for portable high energy density devices, the rechargeable Li-ion battery has become one of the more viable energy storage systems for large scale commercial EVs because of their higher energy density to weight or volume ratio when compared to other current commercial battery energy storage systems. Various safety procedures for the use of Li-ion batteries in both consumer and EV applications have been developed by the international associations. The test procedures studied in this dissertation demonstrated the importance of determining the true capacity of a cell at various discharge rates. For this, the well known Peukert test was demonstrated. The study also showed that cells with different battery geometries and chemistries would demonstrate different thermal heating during discharge and slightly different Ragone results if different test methods were used as reported in the literature. Accelerated ageing tests were done on different cells at different Depth-of-Discharge (DoD) regions. The different DoD regions were determined according to expected stresses the electrode material in a cell would experience when discharged to specific DoD that follows the discharge voltage profile. Electrochemical Impedance Spectroscopy (EIS) was used to measure various electrochemical changes within these cells. The EIS results showed that certain observed modelled parameters would change similarly to the ageing of the cell as it aged due to the accelerated testing. EIS was also done on cells at different State-of-Charge (SoC) and temperatures. The results showed that EIS can be used as an effective technique to observe changes within a Li-ion cell as the SoC or temperature changed. For automotive vehicles that are powered by a fuel cell or battery, a supercapacitor can be coupled to a battery in order to increase and optimize the energy and power densities of the drive systems. A test procedure in the literature that evaluated the use of capacitors with Pb-acid batteries was applied to Li-ion type cells in order to quantify the increased power due to the use of a supercapacitor with a Li-ion cell. Both a cylindrical LiCoO2 cell and a VRLA Pb-acid cell showed some additional charge acceptance and delivery when connected to the supercapacitors. A LiMn2O4 pouch cell showed significant charge acceptance and delivery when connected to supercapacitors. The amount of additional charge acceptance and delivery of the different combinations could be explained by EIS, in particular, the resistance and capacitance of the cell in comparison to the combination of the cell and supercapacitor. A large capacity LiCoO2 cell showed high charge acceptance and delivery without connection with a supercapacitor. The study proved that EIS can be used to model the changes within cells under the different conditions and using different test procedures.

The objective of this research is to develop suitable models to simulate and analyse Electrical Vehicle (EV) power-trains to identify and improve some of the deficiencies of EVs and investigate new system architectures. Although some electro-chemical batteries improvements have lately been achieved in specific-energy, the power density is still low. Therefore, an efficient, cost-effective and high power density support unit could facilitate EV competitiveness compared to conventional internal combustion engine powered vehicles in the near future. The Na-Ni-Cl2, or ZEBRA battery as it is most commonly known, has good energy and power densities; it is very promising electro-chemical battery candidate for EV's. The thesis presents a detail simulation model for the ZEBRA technology and investigates its application in an EV power-train with regard to state-of-charge and voltage transients. Unlike other battery systems, the ZEBRA technology can sustain about 5-10% of failed cells. While this is advantageous in single series string or single battery operation it is problematic when higher numbers of batteries are connected in parallel. The simulation model is used to investigate faulted operation of parallel battery configurations. A non-linear capacitance versus voltage function is implemented for the supercapacitor model which yields good energy and terminal voltage predictions when the supercapacitor is cycled over dynamic regimes common to EV applications. A thermal model is also included. Multiple energy source systems are modelled and studied in the form of an energy dense ZEBRA battery connected in parallel with a power dense supercapacitor system. The combination is shown to increase available power, reduce the maximum power demanded from the battery and decrease battery internal power loss. Consequently, battery life would be increased and more energy would be recovered from regenerative braking, enhancing the energy conversion efficiency of the power-train.A combination of ICE and ZEBRA battery is implemented as a range extender for London taxi driving from Manchester to London. The hybridisation ratio of the system is discussed and applied to fulfil the requirement with minimum emissions. This study offers a suitable model for different energy sources, and then optimises the vehicle energy storage combination to realize its full potential. The developed model is used to assess different energy source combinations in order to achieve an energy efficient combination that provides an improved vehicle performance, and, importantly, to understand the energy source interconnection issues in terms of energy flow and circuit transients.

This thesis investigates the economic viability of a grid connected PV system integrated with battery storage in a multifamily home in Sweden. In addition, a fleet of electric cars is added to the system and its economic feasibility is analyzed. The analysis is further classified based on the roof area available for PV installation, wherein system 1 considers nearly the entire roof area of 908 m2 and system 2 is assumed to have less than half the roof area of 360 m2 for PV installation. To help with the assessment, five scenarios are created; where scenario one represents a baseline Swedish cooperative without PV, scenario two includes a PV system; scenario three incorporates battery storage; four considers an electric vehicle fleet embedded into the system and scenario five has a fleet of gasoline cars. These scenarios are applied to the two systems and their results compared. To address the question of this thesis both scenarios 2 and 3 are simulated in System Advisor Model (SAM) and scenario 4 is modeled in Matlab. The outputs are exported to Excel in order to obtain the Net Present Value (NPV), which is the economic indicator for this assessment. In none of the tested scenarios the NPVs’ are positive and the best result is observed in a PV system installed with battery storage in a roof area of 360 m2, which has a NPV of -82,000 SEK. A sensitivity analysis is done to assess the changes in NPV by varying the input parameters. It is concluded that battery storage is not yet economically viable in a Swedish multifamily house.

Electric vehicles (EVs) have emerged to be the future of transportation as the world observes its rising demand and usage across continents. However, currently, one of the biggest bottlenecks of EVs is the battery. Small batteries limit the EVs driving range, while big batteries are expensive and not environmentally friendly. One potential solution to this challenge is the deployment of charging roads, i.e., dynamic wireless charging systems installed under the roads that enable EVs to be charged while driving. In this thesis, we establish a framework using stochastic geometry to study the performance of deploying charging roads in metropolitan cities. We first present the course of actions that a driver may take when driving from a random source to a random destination, and then analyze the distribution of the distance to the nearest charging road and the probability that the trip passes through at least one charging road. These probability distributions assist not only urban planners and policy makers in designing deployment plans of dynamic wireless charging systems, but also drivers and automobile manufacturers in choosing the best driving routes given the road conditions and level of energy of EVs.

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

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)

Battery electric vehicles (BEV) powered by renewable energy are expected to enable a largedecarbonization of the land-based transport. Recent estimations of the International EnergyAgency suggest that BEVs could grow 20-fold by 2030, reaching 200 to 350 million unitsglobally. However, the environmental impacts of BEVs remains a critical issue to be addressed.Batteries are responsible for 80% of the life cycle environmental impacts of BEVs, mainly dueto the extraction of raw materials, manufacture and charge. A concept that aims at avoiding theexploitation of new materials by extending the lifetime of resources and products is circularity.Among various circular business models, one that so far has not been substantially addressedin the literature is battery leasing.This thesis investigates the economic and environmental impacts of leasing batteries for BEVsas a circular business model and compares them to those of the linear model of selling-buyingbatteries. For doing this, we combine three models, namely a battery fleet model, a net presentvalue (NPV) model and a cradle-to-grave life cycle assessment (LCA). In contrast to commonLCAs, our battery fleet model considers different types of driving profiles instead of the typical‘average’ profile, which offers a more accurate depiction of reality.Results indicate that leasing batteries may be as profitable as selling them, but leasingcompanies may require higher revenues and pay higher taxes to attain the same NPV as selling.To generate more income, companies would need to charge fees to customers that are notalways beneficial for them. In fact, buying the battery remains the cheapest option for usersdriving more than 10 thousand km/year, which is the majority. From an environmentalperspective, LCA results show that environmental benefits of leasing batteries compared toselling them are marginal. This suggests that while leasing batteries offer some advantages(e.g., making BEVs more affordable, facilitating flexibility to users, promote the repairing,repurpose and recycling of batteries, etc.), it is unlikely to improve the cost-effectiveness andenvironmental impact of buying/selling them.

Technological advancements in battery electric vehicles (BEVs) have developed alongside increases in vehicle size and the introduction of vehicle styling more similar to internal combustion engine vehicles (ICEVs). Increases in the distance a BEV can travel on a single charge have been accompanied by the ability to recharge the vehicle much faster than the BEV models available just 10 years ago. The Environmental Protection Agency (EPA) reports for model year 2021 include 40 BEV models and many manufacturers have signaled plans to increase the number of battery electric vehicle models offered. As more consumers consider purchasing a battery electric vehicle the question of how well that vehicle can meet all their needs is asked more frequently. This research examines the current DC-Fast charging infrastructure to evaluate how the current distribution of chargers impacts consumer convenience for non-commute routes. No study has evaluated the impact that the current DC-Fast charging infrastructure has on the consumer driving experience and we fill this research need because it will allow consumers to understand more accurately how a (BEV) may meet their needs while also allowing BEV manufacturers to better understand the impacts of potential investments in charging infrastructure. The authors examine over 30,000 pairs of simulated BEV and ICEV routes and compare the distance and duration variations for each pair. Due to our effort to consider the suitability for long distance trips, we have ensured that more than 50% of the simulated routes have a minimum travel distance of 500 miles and over 15% of the routes exceed 1000 miles. Working from this data, 99.7% of the locations in a sample of 360 places in the contiguous U.S. can be reached without relying on the ability to charge a BEV overnight. We further identify a median increase in BEV trip duration of 13.1% and a median increase in distance of 0.06%. The differences in median travel time, particularly when trips exceed 400 miles suggests that long trips made with a BEV may result in longer total travel time, however, differences in route length between BEVs and ICEVs were minimal. These findings serve as the foundation to discuss challenges and solutions related to widespread non-commuter adoption of BEVs in a variety of geographic locations, including how and where the consumer experience may vary. The results from this work will support consumer awareness about the ability of a BEV to meet their needs as well to aid in the evaluation of infrastructure investment as it relates to improving the consumer experience. The methods employed serve as a foundation for future work to investigate the relationship between vehicle type and consumer experience as well as to advance algorithms capable of evaluating routes that require a selection to be made from a set of optional stops. / Master of Science / Technological advancements in battery electric vehicles have developed alongside increases in vehicle size and the introduction of vehicle styling more similar to the gasoline powered internal combustion engine vehicles that many people currently own. Increases in the distance a vehicle can travel on a single charge have been accompanied by the ability to recharge the vehicle much faster than the battery electric vehicle models available just 10 years ago. The Environmental Protection Agency reports that there are 40 battery electric vehicle models available for model year 2021 and many manufacturers have signaled plans to increase the number of battery electric vehicle models offered. As more consumers consider purchasing a battery electric vehicle the question of how well that vehicle can meet all their needs is asked more frequently. This study examines one of the factors that impact the answer to that question: how does the driving experience vairy between gasoline powered vehicles and battery electric vehicles when long trips must be made. The distance and total time to complete the trips were compared across more than 30,000 pairs of routes within the lower 48 states of the United States and the District of Columbia. Battery electric vehicle routes were modeled based on the capabilities of Tesla vehicles due to the well-developed charging infrastructure that supports them. More than 50% of the routes examined exceed 500 miles, emphasizing the focus on long distance travel. Many routes with a total length of less than 400 miles were found to have little or no difference in total travel time or travel distance. However, when trips with a length of 500 miles or more are included the median difference in travel time is 13.1% accompanied by a minimal difference in travel distance of 0.06%. Due to the rapidly increasing travel range of battery electric vehicles and the speed at which they can recharge combined with the frequent installment of new charging locations throughout the United States it is expected that these differences would be smaller today than at the time this study was conducted. The results of this study can be used by consumers to establish realistic expectations regarding how the experience of traveling long distances in a battery electric vehicle may compare with the gasoline powered vehicle they are already familiar with. Battery electric vehicle manufacturers and others considering investments in charging infrastructure may also apply the findings discussed in this study to better communicate the long-distance performance of their vehicles with consumers and identify locations where improvements in the charging infrastructure would be most beneficial to the consumer experience. Future work is needed to explore how the long-range travel experience has continued to improve. The framework of this study provides a foundation for further evaluation of the impact that vehicle and infrastructure developments may have on the consumer experience.

The source-to-wheel efficiency of today’s electrified vehicles already far surpasses the efficiency of strictly gasoline vehicles. As sources of electricity become cleaner and more efficient, and as gasoline becomes more scarce, the need for transportation electrification is increasingly economically and environmentally driven. The automotive industry primarily makes use of permanent magnet synchronous machines (PMSMs) and induction machines (IMs), the latter has the cost advantage of containing no rare earth metals. This thesis studies two different induction motors for electrified powertrain applications using a novel optimization algorithm to create efficiency maps and compare the efficiencies of the two motors. Induction motors are difficult to banchmark due to their complicated control schemes. Each point in their operating range can be achieved with an infinite number of current/slip combinations and therefore has infinite potential efficiencies. The proposed algorithm limits the number of simulations needed to benchmark an induction machine, and provides a clear and unbiased way to compare machines based on losses at their most efficient current/slip combinations over their entire operating range. The proposed algorithm is able to calculate losses within 5% accuracy of simulation values for both machines. The first motor studied makes use of stranded windings and geometry parameters from the Tesla Motors patents. The efficiency map created has a peak efficiency of 96% and corresponds closely to an efficiency map for a similar motor found in literature. The second motor makes use of copper bar windings, which are easier to manufacture and have lower material costs. Bar windings, typically have lower resistance and stator copper losses at low speeds, but higher effective resistance and stator losses at high speeds due to eddy effects. The motor modelled was intended simply to compare the stranded and bar windings, and to see the advantages and disadvantages. For this reason, no other changes are made to the winding layout or motor geometry, including changes that would reduce the eddy effect. The resultant efficiency map has a peak efficiency of only 90%, performing worse than the stranded wound motor across most of its operating range. At very low speeds, under 1000 rpm, the efficiency of the bar wound machine is better than that of the stranded machine. The bar wound machine also has the advantage of being over 80% efficient everywhere. The author suggests that future research focus on applying the proposed benchmarking algorithm to stator bar motors designed to limit eddy effects. Strategies include changing the slot opening shape, increasing the number of stator bars, and moving the stator bars away from the air gap. / Thesis / Master of Applied Science (MASc)

Due to technological developments and raising environmental concerns, vehicle industry is ina transformation process. Current dominant design in the industry is the internal combustionengine vehicle but there are already different alternative vehicles like electric vehicles (EV),hybrids, and vehicles running on ethanol or hydrogen. These alternatives started to expandand they are competing to have a strong position in the market. The question is whichtechnology (EV, hybrid, ethanol) will have an important position in the future. This studyfocuses on the progress of electric vehicles towards being the dominant design in the vehicleindustry and aims to give advices and suggestions to electric car manufacturers what theyshould develop and concentrate on in the future. To achieve this aim, interviews with Renaultand Stockholm Municipality is conducted and analyzed in detail. Many manufacturers areinterested in EV technology and started to invest in the technology to have a strong position inthe future. Although EVs are ready to expand, there are still some obstacles in their way.Some of these problems can be solved in a short term, while others, mostly technology relatedimprovements still require time.