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Thermal expansion can be an issue in solid busbars, the expansion is caused by several factors and can cause plastic deformation in connection points or structure around it. The expansion occurs due to temperature differences in the busbar as a result of altered ambient temperature and/or joule heating. The environment where a vehicle is used can be harsh and varying in temperatures a lot. For future fast charging systems, a high amount of current will be passed in the conductors. In a stationary installation, this could be solved by increasing the cross-section area. In vehicles, the weight, cost, and space limitations callfor optimization of the conductor. In this thesis, there are several geometrical alterations done to the busbar to investigate the possibility to reduce the amount of stress acting on the connection points. The main geometrical evaluation is to compare a straight busbar to a U-shaped busbar. In the U-shape, the height, bend radius, and cross-section shape are investigated. To investigate this issue a simulation model was developed using Comsol, this software was used to evaluate stress values, max temperature, losses, and displacement. The results from the simulation showed that the U-shape has a large potential to reduce the amount of stress. Also, the cross-section shape tests showed that the steady-state temperature was lower for the more flatter shaped busbar. This is true both for the U-shape and straight busbar. This resulted inreduced amount of thermal expansion causing lower amount of stress, without adding any weight. The weight parameter is extremely important for vehicle implementation. The last test is looking at the busbar material where nickel-plated copper is compared to anodized aluminum. This test is divided into two parts, the first one is looking at an aluminum busbar compared to a copper busbar of the same geometry. This test showed that the losses in the aluminum busbar were much higher, but the steady-state temperature and max stress were lower. The second part of the test investigated the compensated aluminum busbar, this one is modeled by compensating the cross-section area for the higher resistance value of aluminum. The results from this busbar compared to the standard-shaped busbar showed a substantially lower stress, temperature and weight. But the overall dimensions are larger due to the compensated cross-section area. Having this larger Cross section area might hinder the implementation of aluminium busbars in parts of the vehicle where there is a lack of space, like in a battery box. / Termisk expansion i solida busbars är ett vanligt problem vid kraftig temperaturvariation. Problemet ökar med längden av busbaren och kan leda till plastisk deformation i infästningen av busbaren. Temperaturvariationen kan ske genom varierad omgivningstemperatur eller genom resistiv uppvärmning. Om en busbar ska användas i ett fordon för kraftöverföring är arbetsmiljön mycket påfrestande. Den termiska uppvärmningen går normalt att motverka genom att öka tvärsnittsarean, men i ett fordon där vikt, kostnad och platsbrist minskar möjligheten för ökad tvärsnittsarea blir optimering av ledaren extra viktig. För att undersöka problemet utvecklades en simuleringsmodell med hjälp av Comsol. Denna programvara använder för att utvärdera spänningskoncentrationer, maxtemperatur, förluster och utböjningar i busbaren. För att undersöka eventuella lösningar togs det fram flera geometriska variationer till busbaren, där möjligheten att använda en “U-form” utgjorde basen i en jämförelse mot en vanlig rakbusbar. För U-formen undersöktes U-höjden, böj-radien samt tvärsnittsformen. Även en jämförelse mellan nickelpläterad koppar och anodiserad aluminiumgenomfördes för att urskilja eventuella för och nackdelar med materialen. Resultaten från simuleringarna visade att U-formen gav klart lägre spänning i kontaktpunkterna. Även tvärsnittsformen påverkade temperaturen och spänningen i busbaren, där den plattare varianten presterade bättre på alla parametrar som undersöktes i simuleringen. För utvärderingen av materialet utfördes två tester, det första testet jämför en busbar i aluminium mot en i koppar med exakt samma geometri, detta testvisade att temperaturen samt spänningen blir lägre i aluminiumvarianten, dock ökar förlusterna kraftigt då aluminium har högre resistans än koppar. I den andra testet användes en kompenserad aluminiumbusbar där tvärsnittsarean har ökats för att ge samma resistans som kopparvarianten. Denna busbar fick en mycket lägre sluttemperatur, spänning och vikt. Förlusterna blev detsamma. Den högre tvärsnittsarean ger dock en fysiskt större busbar.

The past few decades have seen a rapid sales increase and technological development of electric vehicles (EVs). As the key part of the electrical powertrain systems, the traction machine drive systems in modern EVs are composed of voltage source inverters (VSI) and electric machines. In this thesis, multiphase VSIs are studied and designed to achieve volume reductions when compared with existing 3-phase benchmark VSIs. Different existing switching strategies for arbitrary phase number multiphase VSIs are investigated resulting in an understanding of best practice and a newly proposed switching strategy. Thus, the first contribution of this thesis is switching strategies that support subsequent investigations and experimental validation. DC-link capacitor and heat sink are two bulkiest components in VSIs and hence it is more efficient to decrease their volumes to achieve the compactness improvement. The investigation methodology and procedure for arbitrary phase number VSI DC-link capacitor requirements, i.e. capacitance and RMS current ratings, are firstly developed. Increased phase number decreases the DC-link capacitor requirements and hence the VSI volume significantly. Throughout this analysis, the connected multiphase machine is considered appropriately, though no electric machine design is described in the thesis. While other authors have studied DC-link current ripple, this thesis qualifies and quantifies the system benefits. This is the second contribution. Multiphase VSIs thermal models are built and their respective thermal performances studied and evaluated against a reference 3-phase benchmark VSI. The power loss deviation among different semiconductor dies is lower or even eliminated in the multiphase VSIs. Furthermore, the multiphase integrated design VSIs have a significant heat sink volume reduction when compared to the 3-phase benchmark VSI. This study and concluding benefits are the third contribution. Finally, comparative test validations are made on an experimental set-up designed to illustrate the benefits of a 9-phase against a reference 3-phase system. Here, the test hardware and implementation are carefully designed to representatively illustrate performance benefits. / Thesis / Doctor of Philosophy (PhD)

This thesis mainly focuses on parallel hybrid electric vehicle energy management problems considering fueling control and air path dynamics of a diesel engine. It aims to explore the concealed fuel-saving potentials in conventional energy management strategies, by employing detailed engine models. The contributions of this study lie on the following aspects: 1) Fueling control consists of fuel injection mass and timing control. By properly selecting combinations of fueling control variables and torque split ratio, engine efficiency is increased and the HEV fuel consumption is further reduced. 2) A transient engine model considering air path dynamics is applied to more accurately predict engine torque. A model predictive control based energy management strategy is developed and solved by dynamic programming. The fuel efficiency is improved, comparing the proposed strategy to those that ignore the engine transients. 3) A novel adaptive control-step learning model predictive control scheme is proposed and implemented in HEV energy management design. It reveals a trade-off between control accuracy and computational efficiency for the MPC based strategies, and demonstrates a good adaptability to the variation of driving cycle while maintaining low computational burden. 4) Two methods are presented to deal with the conjunction between consecutive functions in the piece-wise linearization for the energy management problem. One of them shows a fairly close performance with the original nonlinear method, but much less computing time. / Thesis / Doctor of Philosophy (PhD)

This thesis outlines the development of a control system for a P4-P0 Parallel-Through-The-Road Hybrid Electric Vehicle. This project was part of the EcoCAR Mobility Challenge, an Advanced Vehicle Technology Competition, sponsored by the U.S. Department of Energy, MathWorks and General Motors. The McMaster Engineering EcoCAR team is participating in its second iteration, re-engineering a 2019 Chevrolet Blazer to suit a car-sharing service located within the Greater Toronto Hamilton Area. The proposed architecture uses a 1.5L Engine together with a Belted Alternator Starter motor connected to the traditional low voltage system. The rear axle is electrified containing an Electric Machine, a power oriented Battery Pack and team-designed gear reduction as well as a clutch. The whole rear powertrain is operating at high voltage and has no connection to the traditional low voltage system. Fuel economy improvements up to 12% can be expected while maintaining stock performance targets. A vehicle simulation model was built to accompany the vehicle design process. This includes a mathematical representation of all powertrain components, the development of energy management algorithms, the design of the Hybrid Supervisory Controller structure, and validating and discussing gathered results. Furthermore, all necessary controllers were chosen and communication within them was established by designing the serial data architecture. The developed energy management algorithm is customized to utilize the strengths of all components and this specific architecture. A simple rule-based algorithm is used to operate the engine as close as possible to its most fuel efficient operation point at any time. The P4 and P0 motor are used to apply supportive torque to the engine or load the engine with a negative torque. In that way the energy can be regenerated inside the powertrain and charge sustaining operation v can be achieved. Fuel economy and performance targets are used to discuss the assumed performance of the vehicle once re-engineered. The set targets range from city and highway fuel economy to IVM – 60 mph acceleration time. Overall the developed control system suits a car-sharing service with its ability to adapt to the occurring driving situations ensuring a close to optimal operation for any known or unknown driving situation. It focuses on modularity, simplicity and functionality to allow a working implementation in future years of the EcoCAR Mobility Challenge. / Thesis / Master of Applied Science (MASc) / During the re-engineering of a Hybrid Electric Vehicle different expectations must be considered, for example set government fuel economy regulations, defined performance targets, novelty in innovation, stakeholder expectations as well as the used vehicle platform and the available components. The re-engineering process will be done according to the vehicle development process of the EcoCAR Mobility Challenge. Summarized expectations are the use of this vehicle inside a car-sharing service for the Greater Toronto Hamilton Area targeting “Millennials” while focusing on fuel economy improvements and a low cost of ownership. The research shown in this thesis is set by the requirements derived from the expectations mentioned above. One point of interest is achieving a working control system able to operate close to an optimal state to maximize fuel efficiency and ensuring stock vehicle performance targets. Therefore, the control system has to use the electrification components in an intelligent way. Defining what intelligent control of the engine and the electrification components was one of the main challenges. This thesis outlines how developing a control system for a Hybrid Electric Vehicle can be realized while ensuring that all included interests are met. The object of this research contains choosing the necessary controllers, building a sufficient vehicle simulation model, developing the energy management algorithm, validating the model performance and evaluating the gathered results.

Modeling and Implementation of a Hardware Efficient Low-Voltage-To-Cell Battery Balancing Circuit for Electric Vehicle Range Extension / One disadvantage of electric vehicles is their limited driving range when compared to internal combustion engine vehicles. Battery packs are also a significant cost to electric vehicle manufacturers, and lithium-ion battery cells must remain within controlled voltage limits. Thus, the requirements for the electric system are to be cost effective, perform battery management, and make it as efficient as possible to increase its range. Battery packs are typically constructed from around 100 battery cells in a series connection. During use of an electric vehicle, the battery cells become mismatched due to small differences in capacity. This effect is further amplified as the electric vehicle ages. Diverging cells cause issues during driving, since weak cells can limit the useable capacity of the vehicle. In order to use the whole capacity of the battery pack, and thus the entire range of the electric vehicle, the cells should be balanced. Strong cells should distribute their excess capacity to weaker cells during driving. The thesis presents the design, modeling and implementation of a novel hardware-efficient battery balancing circuit. First, the theory behind battery balancing is presented. Next, existing battery balancing circuits are compared. Finally, the proposed battery balancing circuit is discussed. The design of the proposed topology is examined in detail. Simulations show that the circuit transfers energy between non-adjacent cells throughout the entire pack. Experimental work is performed on two custom printed circuit boards, a 12 cell lithium-ion module, and a 12V lead acid battery. The results confirm the function of the prototype. The effect of the battery balancing circuit on driving range is examined with vehicle modeling simulations. A 2018 Chevrolet Bolt model is produced and capacity differences are given to each cell. The proposed topology balances the cells while driving, extending driving range on UDDS and HWFET drive cycles. / Thesis / Master of Applied Science (MASc) / One disadvantage of electric vehicles is their limited driving range when compared to internal combustion engine vehicles. Thus, there is a requirement to make the electric system as efficient as possible in order to increase its range. A large piece of the electric system includes the battery pack. Battery packs are typically constructed from around 100 battery cells in a series connection. During use of an electric vehicle, the battery cells become mismatched. This effect is also amplified as the electric vehicle ages. In order to use the whole capacity of the battery pack, and thus the entire range of the electric vehicle, the cells should be balanced. The thesis presents the design, modeling and implementation of a novel hardware efficient battery balancing circuit. The effect of the battery balancing circuit on driving range is examined.

The electrification of transportation is gradually becoming more prominent as it is more efficient and sustainable than conventional transportation alternatives found today. At the centre of this growth is battery testing and research, as they are the primary energy storage devices used to power electric vehicles. With the growing complexity of battery systems, testing and monitoring their performance relies on highly specialized and precise equipment. Furthermore, the use of battery models helps researchers improve their research while reducing the time and costs involved in testing. As such, accurate battery modelling is a critical component in predicting how a battery will behave in specific applications and under various conditions. In this research, a lithium-ion cell is tested extensively, and its performance is characterized across a wide range of operating conditions including temperature, current rates and state of charge (SOC) values. An equivalent circuit model for impedance modelling is proposed, which utilizes constant phase elements represented in the time domain to improve fitting accuracy. This is done concurrently with the development of a state of the art, fully automated battery test system which is showcased throughout the course of the research. In addition to this, an analysis is conducted on the low frequency impedance data used during research, as well as its effect on model accuracy. To provide significance behind the results and relevance to real-world applications, all of the impedance modelling is experimentally validated using temporal drive cycle data. This research was able to demonstrate that the use of a ZARC element can improve the mid-frequency fitting of impedance data relative to a conventionally used modelling approach. It also showcases how the use of low frequency electrochemical impedance spectroscopy (EIS) data can negatively impact the accuracy of impedance modelling. / Thesis / Master of Applied Science (MASc)

A novel belt alternator starter (BAS) is proposed to replace the starter and alternator in a hybrid electric vehicle. The BAS designed utilizes an 18 rotor, 12 stator pole switched reluctance machine (SRM) configuration, with concentrated bar windings wound in parallel. Through iteration of various machine geometry parameters, the SRM can meet the torque and speeds demands over standardized drive cycles described by the US Environmental Protection Agency. / With the depletion of oil wells and changing global climate, a large emphasis is placed on the research, development and adoption of electric vehicles (EVs) to replace vehicles driven by internal combustion engines (ICEs). However the global supply chain is still not ready for such a large demand in EVs; therefore hybrid electric vehicles (HEVs) aim to ease the transition between ICEs and EVs. The research outlined in this thesis investigates the design of a 18 stator, 12 rotor pole (18/12) configuration switched reluctance machine (SRM) utilizing novel technologies for use as a belt alternator starter (BAS) motor in an HEV. Background research on current trends and technologies for electric motors and vehicles is performed before evaluating initial geometry for the motor core to be designed. Initial geometry is brought into JMAG to develop an electromagnetic model and begin the geometry optimization. The 18/12 design process highlights how changes to motor parameters from a geometry and winding standpoint will affect motor performance. After the motor core geometry yields suitable performance, a mechanical design is proposed encompassing the rotary assembly, cooling as well as solutions for mounting. / Thesis / Master of Applied Science (MASc) / Hybrid electric vehicles are becoming more prevalent as stricter restrictions are placed on fuel economy and emissions targets. Full electric vehicles on the other hand have not yet become the standard form of transportation due to the limits on range and infrastructure. Because of this, automotive manufacturers are researching and developing new methods in which they can meet these restrictions and limitations. Switched reluctance motors aim to be a solution to meet these demands while forging a new path by alleviating the demand on rare earth metals for the motor core. In this thesis, a design is proposed to fill an existing role in vehicle electrification best suited for a belted alternator starter.

Along with the growth of electricity demand and the penetration of intermittent renewable energy sources, electric power distribution networks will face more and more stress conditions, especially as electric vehicles (EVs) take a greater share in the personal automobile market. This may cause potential transformer overloads, feeder congestions, and undue circuit failures. Demand response (DR) is gaining attention as it can potentially relieve system stress conditions through load management. DR can possibly defer or avoid construction of large-scale power generation and transmission infrastructures by improving the electric utility load factor. This dissertation proposes to develop a planning tool for electric utilities that can provide an insight into the implementation of demand response at the end-user level. The proposed planning tool comprises control algorithms and a simulation platform that are designed to intelligently manage end-use loads to make the EV penetration transparent to an electric power distribution network. The proposed planning tool computes the demand response amount necessary at the circuit/substation level to alleviate the stress condition due to the penetration of EVs. Then, the demand response amount is allocated to the end-user as a basis for appliance scheduling and control. To accomplish the dissertation objective, electrical loads of both residential and commercial customers, as well as EV fleets, are modeled, validated, and aggregated with their control algorithms proposed at the appliance level. A multi-layer demand response model is developed that takes into account both concerns from utilities for load reduction and concerns from consumers for convenience and privacy. An analytic hierarchy process (AHP)-based approach is put forward taking into consideration opinions from all stakeholders in order to determine the priority and importance of various consumer groups. The proposed demand response strategy takes into consideration dynamic priorities of the load based on the consumers' real-time needs. Consumer comfort indices are introduced to measure the impact of demand response on consumers' life style. The proposed indices can provide electric utilities a better estimation of the customer acceptance of a DR program, and the capability of a distribution circuit to accommodate EV penetration. Research findings from this work indicate that the proposed demand response strategy can fulfill the task of peak demand reduction with different EV penetration levels while maintaining consumer comfort levels. The study shows that the higher number of EVs in the distribution circuit will result in the higher DR impacts on consumers' comfort. This indicates that when EV numbers exceed a certain threshold in an area, other measures besides demand response will have to be taken into account to tackle the peak demand growth. The proposed planning tool is expected to provide an insight into the implementation of demand response at the end-user level. It can be used to estimate demand response potentials and the benefit of implementing demand response at different DR penetration levels within a distribution circuit. The planning tool can be used by a utility to design proper incentives and encourage consumers to participate in DR programs. At the same time, the simulation results will give a better understanding of the DR impact on scheduling of electric appliances. / Ph. D.