This thesis investigates the feasibility of using Silicon Carbide (SiC)-based multiphase inverters (MPIs) for transportation electrification applications. The research begins with a comprehensive review on the state-of-the-art of MPIs, focusing on voltage source inverters (VSIs) and nine-switch inverters (NSIs), with five-, six-, and nine-phase configurations. The quantitative and qualitative analyses demonstrate that the six-phase VSI is the most promising topology, offering reduced DC-capacitor requirements, lower cabling cost, and higher fault tolerance capability while maintaining the same efficiency and power device count of a three-phase VSI. The feasibility of the SiC-based six-phase inverter is further investigated at the vehicle level, where a vehicle model is developed to study the energy consumption under different drive cycles. The resulting indicate an 8% improvement in vehicle mileage and fuel economy of the SiC-based six-phase inverter compared to its Si-based counterpart. This thesis also examines the current and voltage stresses on the DC-bus capacitor in two-level six-phase VSIs. The study considers two configurations of load/winding spatial distribution: symmetric and asymmetric. Consequently, analytical formulas for the DC-bus capacitor current and voltage ripples are derived. Furthermore, simple capacitor sizing rules in six-phase VSIs with different load configurations are provided. The accuracy of the derived formulas is verified by simulation and experimental testing, and their boundary conditions are identified. Six-phase VSI supplying symmetric loads was found to yield the smallest capacitor size. Based on the foregoing technology review and analyses, a holistic design methodology for a 100 kW SiC-based six-phase traction inverter for an electric vehicle application is presented. The proposed methodology considers the device power level, where discrete SiC MOSFETs are utilized, and the DC-capacitor sizing, where a multi-objective optimization algorithm is proposed to find the most suitable capacitor bank. Mechanical and thermal design constraints are also explored to deliver a compact housing with an integrated coolant channel. The resultant inverter design from the proposed electrical-thermal-mechanical design methodology is prototyped and experimentally tested, demonstrating a 7% reduction in DC-capacitor volume and 21% reduction in cabling cost when compared to conventional three-phase inverters of the same volt-ampere rating. The peak power density of the prototype inverter is 70 kW/L, demonstrating a compact design. Besides, the proposed design is benchmarked against commercial six-phase inverter models, whereby the competitiveness of the proposed design is highlighted. Finally, the unique control aspects of six-phase electric motor drives are investigated to identify suitable controls strategies for various operating conditions. The study places special emphasis on high-speed operation and evaluates several overmodulation techniques. An adaptive flux-weakening control algorithm is also proposed for the six-phase motor drive, which significantly improves the DC-bus voltage utilization of the inverter when used in conjunction with overmodulation. Overall, this thesis provides a comprehensive study of SiC-based six-phase traction inverters and proposes a holistic design methodology that considers electrical, thermal, and mechanical aspects. The results demonstrate the feasibility and advantages of SiC-based six-phase traction inverters for electric vehicle applications. / Thesis / Doctor of Philosophy (PhD) / Electric cars are continuously challenged to meet regulatory mandates that become stricter by the day. This is driven by the need for a clean, reliable, affordable, and sustainable transportation system. In this research, a novel, more reliable, and cost-effective power control unit (PCU) is proposed. The PCU manages the power flow regulation between the battery and the motor(s). The proposed PCU employs the same number of devices as a traditional counterpart, yet in a more modular architecture that doubles the safety factor compared to the standard design. In fault scenarios where the traditional PCU would fail, the proposed PCU would continue operating at half power, allowing the driver and passengers to reach a safe destination before the car is repaired. Extensive analyses were undertaken to identify an optimal design in terms of performance, size, and cost. Then, an engineering prototype is constructed and tested on an electric drivetrain testbed. Finally, the prototype is benchmarked against commercial competitors in the market to establish its economical feasibility.

Traffic congestion in large urban and metropolitan areas is a substantial problem plaguing these areas. Not only are commuters losing valuable time, but greenhouse gas emissions are substantially worse because of congestion. Considerable research and development into next generation electrified aircraft is ongoing to introduce air mobility as a viable new means of transporting people and goods across long commutes. This development extends into commercial aviation as a whole as a means of reducing the industry’s carbon footprint with new aircraft designs that employ electrified propulsion systems. Many electrified aircraft projects are currently underway, ranging from small commuter aircraft all the way to large twin-aisle aircraft, and part of the development scope for alot of these projects is creating highly robust and power dense electric machines that replace the current state-of-the-art. The axial flux permanent magnet synchronous machine is an exciting candidate for aircraft propulsion due to its exceptional torque density and compact axial nature. In this thesis, the mechanical design for three generations of axial flux permanent magnet synchronous machines is discussed. These machines serve as development phase prototypes for machines that are ultimately intended for propulsion applications in commercial aviation, particularly for eVTOL aircraft. The motivation for electrification in the commercial aviation industry is discussed, followed by an overview of the development landscape for electrified propulsion systems in commercial aviation, focusing primarily on electric machines that are currently state-of-the-art or are set to be in the near future, as well as what is required for future electric machines in terms of power output and power density. The axial flux architecture is then presented, including a high-level comparison to the radial-flux architecture, an overview of the various axial flux machine designs and topologies, and a discussion of the inherent mechanical design challenges associated with the axial flux architecture. The yokeless and segmented armature axial flux permanent magnet synchronous machine design was selected for the machines developed as part of the research for this thesis, and the discussion of the mechanical design of these machines is broken up into the two core sub assemblies: stator assembly and rotating assembly. High-level design methodologies are introduced for both sub-assemblies, which is further broken down into different approaches pertaining to each generation. The first and second generation designs are presented at a high level, followed by deep-dives into the complete mechanical design for the third generation stator, the bearing selection, arrangement, and analysis for the third generation rotating assembly, and adhesive characterization trials used to guide adhesive selection for rotor magnetics retention in the second and third generation machines. The current status of the machines and any outcomes from testing that has been conducted thus far, particularly with respect to performance, is presented at the end. / Thesis / Master of Applied Science (MASc)

The world is looking for greener solutions and so is the mining industry. This quest has led to the question whether it is possible to have a completely electric rock drill. This work carries out an initial exploration of completely electrified percussion. Furthermore, it compares the preliminary performance of an electrified rock drill against a hydraulic counterpart. A mathematical model for an electromagnetic linear motor was developed and simulated as a component in the simulation software Hopsan. This component was then incorporated into a electromagnetic rock drill model which uses components from Epiroc’s in-house developed library. The electromagnetic rock drill model was then optimised and used to obtain the performance characteristics such as impact energy and frequency which were compared against one of the hydraulic rock drill models, COP 1838. The results show that it is possible to reach the same performance as the COP 1838 with enough input current. The characteristics were then studied with respect to variation of physical parameters of the electromagnetic linear motor and input current. Finally some limitations and strengths of the electromagnetic rock drill concept are discussed and some conclusions are presented.

As new emission regulations in the EU set more stringent requirements on greenhouse gas (GHG) emissions, original equipment manufacturers (OEM) must find ways to align with the EUs sustainability goals. By transitioning to more electrically driven machinery, operators of off-highway vehicles can benefit from better fuel economy, lower greenhouse gas emissions and less air pollution. This study explores the possibilities of electrifying the hydraulic tilt function of the Steelwrist X18 Tiltrotator, a critical component in off-highway vehicle equipment. According to Steelwrist, other original equipment manufacturers such as VOLVO CE have asked when Steelwrist can deliver a fully electric tiltrotator. Key findings show that the chosen electromechanical actuator concept, the EWELLIX CASM-100-RA, with a 8.2 [kW] motor kit, have acceptable performance, but does not to meet every specified requirement. Installing two CASM-100-RA actuators on the X18 results in a 17% weight increase that would adversely affects the excavator’s load-carrying capacity and work efficiency. Despite the drawbacks, the paper acknowledges that the other considered concepts would have resulted in even heavier and/or bulkier solutions / I och med nya utsläppsregler inom EU som ställer högre krav på växthusgasutsläpp måste tillverkare av originalutrustning hitta sätt att anpassa sig till EU:s hållbarhetsmål. Genom att övergå till mer elektriskt drivna maskiner kanförare av anläggningsfordon dra nytta av bättre bränsleekonomi, lägre utsläpp av växthusgaser och minskade luftföroreningar. Denna studie utforskar möjligheterna att elektrifiera den hydrauliska tiltfunktionen på Steelwrist X18 Tiltrotator, ett vanligt verktyg inom anläggningsindustrin. Enligt Steelwrist har andra tillverkare av originalutrustning, såsom VOLVO CE, visat intresse för när Steelwrist kan leverera en helt elektrisk tiltrotator. Elektrifieringen av anläggningsindustrin är fortfarande i sin linda och endast kompaktfordon finns för närvarande på marknaden. Detta är en anledning till att det ännu inte finns en lösning på detta problem. En annan förklaring är den oöverträffade effekttätheten hos konventionella hydraulcylindrar, vilket gör dem svåra att ersätta. Forskningsfrågorna besvarades genom en grundlig undersökning av den senaste tekniken och experiment för att testa den hydrauliska prestandan hos X18 Tiltrotator. Huvudresultaten visar att det valda EMA-konceptet, specifikt EWELLIX CASM-100-RA med 8,2 [kW]-motor, inte uppfyller de inledande kravspecifikationerna på grund av en oacceptabel ökning av den totala vikten på X18 Tiltrotator .Viktökningen skulle påverka grävmaskinens lastkapacitet och arbetskapacitet negativt. Trots nackdelarna tilläggs det att de andra övervägda koncepten skulle ha resulterat i ännu tyngre och/eller skrymmande lösningar. Denna masteruppsats har belyst de mest utmanande aspekterna av att elektrifiera tiltfunktionen i X18 tiltrotatorn. Dessutom har betydelsen av omfattande och detaljerad prestandadata varit en annan nyckelinsikt i projektet. Prestandadata har visat sig vara avgörande vid utformningen av elektriska tiltaktuatorer för denna tillämpning. Framtida arbete kan ytterligare undersöka anpassade elektromekaniska aktuatorer.

No description available.

No description available.

The emission-heavy open-pit mining industry is exploring a new emission-free era with electrified autonomous haulers. The new technology has challenges, such as designing charging infrastructure for complex environments. This thesis addresses these challenges with a simulation model. This thesis aims to create a foundation and enhance decision-making for designing and evaluating charging infrastructure for Volvo Autonomous Solutions. The paper investigates various charging infrastructure designs using a simulation model verified by Volvo Autonomous Solutions employees, prioritizing minimizing the total cost of ownership and simultaneously meeting the production goal. The project consists of phases such as Needfinding and Research, Modeling, Simulation, and Validation, each aligned with specific activities inspired by Design Thinking principles. The simulation model is developed iterative with a specific site as the case. Several meetings were conducted with the co-advisor and supervisor to validate the simulation model. The thesis has developed a simulation model for charging infrastructures specifically designed for open-pit quarries. The simulation model was developed to make changes to the system easily. Adaptiveness is needed for the constantly changing environment or testing a new open-pit quarry. How to design charging infrastructure for open-pit quarries was found to be a research gap, and there is also an industrial need for guidance on how it should be designed. The scientific contribution concludes that important factors are important in designing charging infrastructure. Whereas the industrial contribution concludes, the simulation model is configured. / Den utsläppstunga dagbrottsindustrin utforskar en ny utsläppsfri era med elektrifierade autonoma dumprar. Den nya tekniken har utmaningar, som att designa laddinfrastruktur för komplexa miljöer. Denna avhandling tar uppdessa utmaningar med en simuleringsmodell. Examensarbetet syftar till att skapa en grund och förbättra beslutsfattandet för design och utvärdering av laddinfrastruktur för Volvo Autonomous Solutions. Uppsatsen undersöker olika designer av laddinfrastruktur med hjälp av en simuleringsmodell som verifierats av anställda på Volvo Autonomous Solutions, med prioritet att minimera den totala ägandekostnaden och samtidigt uppfylla produktionsmålet. Projektet bestod av faser som Needfinding och Research, Modellering, Simulering och Validering, var och en anpassad till specifika aktiviteter inspirerade av Design Thinking principer. Simuleringsmodellen utvecklades iterativt med ett specifik dagbrott som fall. Flera möten genomfördes med företagshandledare och handledare för att validera simuleringsmodellen. Avhandlingen har utvecklat en simuleringsmodell för laddningsinfrastruktur speciellt utformad för dagbrott. Simuleringsmodellen utvecklades för att enkelt kunna göra ändringar i systemet. Anpassningsförmåga behövs för den ständigt föränderliga miljön eller för att testa ett nytt dagbrott. Hur man utformar laddinfrastruktur för dagbrott visade sig vara ett forskningsgap och det finns också ett industriellt behov av vägledning om hur den ska utformas. Det vetenskapliga bidraget drar slutsatser om viktiga faktorer vid utformningen av laddinfrastruktur. Medan det industriella bidraget drar slutsatser om konfigurationen av simuleringsmodellen.

The 2050 national energy scenarios as planned by the DECC, academia and industry specify a range of different decarbonised supply side technologies combined with the electrification of transportation and heating. Little attention is paid to the household demand side; indeed within many scenarios a high degree of domestic Demand Side Management (DSM) is implicit if the National Grid is to maintain supply-demand balance. A top-down, bottom-up hybrid model named Shed-able Household Energy Demand (SHED) has been developed and the results of which presented within this thesis. SHED models six published national energy scenarios, including three from the Department for Energy and Climate Change, in order to provide a broad coverage of the possible energy scenario landscape. The objective of which is to quantify the required changes in current household energy demand patterns via DSM, as are implicit under these highly electricity dominated scenarios, in order to maintain electrical supply-demand balance at the national level. The frequency and magnitude of these required household DSM responses is quantified. SHED performs this by modelling eleven years of supply-demand dynamics on the hourly time step, based on the assumptions of the published energy scenarios as well as weather data from around 150 weather stations around the UK and National Grid historic electricity demand data. The bottom-up component of SHED is populated by 1,000 households hourly gas and electricity demand data from a recently released dataset from a smart metering trial in Ireland. This aggregate pool of households enables national domestic DSM dynamics to be disaggregated to the aggregate household level. Using household classifications developed by the Office for National Statistics three typical ' households are identified within the aggregate pool and algorithms developed to investigate the possible required responses from these three households. SHED is the first model of its kind to connect national energy scenarios to the implications these scenarios may have on households consumption of energy at a high temporal resolution. The analysis of the top-down scenario modelling shows significant periods where electrical demand exceeds supply within all scenarios, within many scenarios instances exist where the deficit is unserviceable due to lack of sufficient spare capacity either side of the deficit period. Considering the level of participation required within the modelled scenarios in order to balance the electricity system and the current lack in understanding of smart metering and Time-Of-Use (TOU) tariffs within households, it would seem there is a disconnect between the electricity system being planned, the role this system expects of households and the role households are willing to play.

Thesis (MBA)--Stellenbosch University, 2014. / Census 2011 put the rate of electrification in South Africa at 84 percent. Even though this is a positive outcome to the previously recorded 34 percent, it has served as a clear indication that the target for Universal Access to Electricity by 2014 as set by President Jacob Zuma is unlikely to be achieved. In June 2013, cabinet approved the implementation of the new household electrification strategy and in support of this decision the Department of Energy was tasked to develop a new electrification roadmap or implementation plan. The intention of this research study has been to contribute to the development of this strategic plan by analysing the status of electrification in KwaZulu-Natal, as extracted from the provincial Geographical Information System, in order to identify the optimal electrification roll out plan and to develop guiding principles for the electrification of the province. The research outcomes provide a view of the current state of electrification within the province, identify the major technical constraints which hinder the progress, and provide recommendations for implementation roll out for KwaZulu-Natal province. The finding of this research is that of the 497 799 thousand un-electrified houses, 169 506 HH are not electrifiable as there is not sufficient capacity on the existing networks to cater for these households. Of those, 132 007 households are dependent on the establishment and construction of new bulk infrastructure such as substations and lines, while 37 499 are dependent on the upgrade or refurbishment of the existing infrastructure. The research has identified and categorised the ‘critical’ bulk infrastructure that will benefit 5 000 households or more as well as the high impact infrastructure projects that cater for 3 000 households or more. The research has also identified municipalities that are above the average of 84 percent electrification and categorised these as quick win areas to help in the progression toward universal access. As the research has also identified the dark havens, named as such due to being less than 50 percent electrified and plagued by technical constraints which makes any electrification of these areas not possible in the next five to ten years. Recommendations for responding to all four categories of findings are put forward.

Renewable energy is key to a sustainable future. However, the intermittency of most renewable sources and lack of sufficient storage in the current power grid means that reliable integration of significantly more renewables will be a challenging task. Moreover, increased integration of renewables not only increases uncertainty, but also reduces the fraction of traditional controllable generation capacity that is available to cope with supply-demand imbalances and uncertainties. Less traditional generation also means less rotating mass that provides very short term, yet very important, kinetic energy storage to the system and enables mitigation of the frequency drop subsequent to major contingencies but before controllable generation can increase production. Demand, on the other side, has been largely regarded as non-controllable and inelastic in the current setting. However, there is strong evidence that a considerable portion of the current and future demand, such as electric vehicle load, is flexible. That is, the instantaneous power delivered to it needs not to be bound to a specific trajectory. In this thesis, we focus on harnessing demand flexibility as a key to enabling more renewable integration and cost reduction. We start with a data driven analysis of the potential of flexible demands, particularly plug-in electric vehicle (PEV) load. We first show that, if left unmanaged, these loads can jeopardize grid reliability by exacerbating the peaks in the load profile and increasing the negative correlation of demand with wind energy production. Then, we propose a simple local policy with very limited information and minimal coordination that besides avoiding undesired effects, has the positive side-effect of substantially increasing the correlation of flexible demand with wind energy production. Such local policies could be readily implemented as modifications to existing "grid friendly" charging modes of plug-in electric vehicles. We then propose improved localized charging policies that counter balance intermittency by autonomously responding to frequency deviations from the nominal frequency and show that PEV load can offer a substantial amount of such ancillary services. Next, we consider the case where real-time prices are employed to provide incentives for demand response. We consider a flexible load under such a pricing scheme and obtain the optimal policy for responding to stochastic price signals to minimize the expected cost of energy. We show that this optimal policy follows a multi-threshold form and propose a recursive method to obtain these thresholds. We then extend our results to obtain optimal policies for simultaneous energy consumption and ancillary service provision by flexible loads as well as optimal policies for operation of storage assets under similar real-time stochastic prices. We prove that the optimal policy in all these cases admits a computationally efficient form. Moreover, we show that while optimal response to prices reduces energy costs, it will result in increased volatility in the aggregate demand which is undesirable. We then discuss how aggregation of flexible loads can take us a step further by transforming the loads to controllable assets that help maintain grid reliability by counterbalancing the intermittency due to renewables. We explore the value of load flexibility in the context of a restructured electricity market. To this end, we introduce a model that economically incentivizes the load to reveal its flexibility and provides cost-comfort trade-offs to the consumers. We establish the performance of our proposed model through evaluation of the price reductions that can be provided to the users compared to uncontrolled and uncoordinated consumption. We show that a key advantage of aggregation and coordination is provision of "regulation" to the system by load, which can account for a considerable price reduction. The proposed scheme is also capable of preventing distribution network overloads. Finally, we extend our flexible load coordination problem to a multi-settlement market setup and propose a stochastic programming approach in obtaining day-ahead market energy purchases and ancillary service sales. Our work demonstrates the potential of flexible loads in harnessing renewables by affecting the load patterns and providing mechanisms to mitigate the inherent intermittency of renewables in an economically efficient manner. / text