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Examensarbetet var en utvärdering av en synkron trefas permanentmagnetmotor med utvändig rotor. Den är tänkt att ingå i ett batterimatat drivsystem för hjälputrustning på segelbåtar. Målen var att kartlägga prestandan i standardutförande samt att hitta de svaga punkterna i konstruktionen. Förslag på hur motorutförandet kan optimeras ska också läggas fram.   Tester och mätningar gjordes i en testuppkoppling med växelriktare, motor och axelkopplad generator. Detta för att kunna få fram fler mätvärden på motorn. Generatorn fick varvtalskortslutning när belastningsströmmen kom upp i 106,1 A och testerna fick avslutas. Koppartråden i lindningarna blev för varm och ytskiktet smälte. Testerna visar att motorn klarar av strömmar upp till 92,1 A och har då en verkningsgrad på 70 %. Det var lindningens strömtålighet tillsammans med effektförlusterna som var den begränsande faktorn i motorkonstruktionen.   Forcerad kylning i form av vattenkyld stator eller att öka lindningstrådens strömtålighet genom att t.ex. en större kabelarea är alternativ för att få till en bättre verkningsgrad och motorprestanda. Ser man till externa lösningar skulle luftkylning med fläkt kunna adderas. / The project was to evaluate a synchronous three-phase permanent magnet motor with brushless outrunner. It is supposed to be a part of an electric drive system for equipment onboard sailing boats. The goal was to investigate the performance of the motor and find the construction weaknesses and to come up with suggestions how to optimize the performance of the motor.   Tests and measurements were made with a test setup that consisted of inverter, motor and a generator connected to the shaft. The generator stator winding had a short circuit when the load current reached 106,1 A and the tests therefore had to end. The copper wire used in the windings temperature became to high and the isolation of the wire melted.  The tests showed that the motor could handle up to 92,1 A with an efficiency of 70%. It was how much current the winding could withstand together with the power losses that was the limiting factor of the motor construction.   Forced cooling with water cooled stator or improving the winding wires ability to handle higher currents by increasing the cable area are both alternatives to get a better efficiency and motor performance.

This thesis demonstrates a practical implementation of a sensorless permanent magnet synchronousmotor (PMSM) drive for vehicle propulsion. The main design parameters and overall properties of themotor drive are derived for the case of an on-board electric powertrain as a substitute to the lift shuttle indownhill (DH) mountain biking.The theory behind field oriented control (FOC) for sensorless PMSMs is analyzed in some detail.Controller-inverter hardware and software are designed and prototyped in accordance with the deriveddesign parameters. Initial tuning and testing in a test bench environment is described. The powertrain isfinally installed on a test bike and tested on an incline. It is found that the performance of the controllerinvertercomplies with the target design parameters.

The growing popularity of instant messaging has led to the conception of several new applications over the span of the past decade. This has opened up an attack surface for cybercriminals to target susceptible app users. GroupMe is a free IM app widely used by students and so far, no comprehensive forensic analysis has been performed to aid forensic practitioners in recovering evidence from GroupMe on smartphones. This research performs a detailed analysis of the digital artifacts left by the app on Android and iOS devices. This was achieved by installing the app on two mobile phones (Samsung Galaxy S7 Edge and iPhone 6), and identifying each artifact created by performing a series of actions in the app ranging from sending texts, to sharing images and documents, along with their location. Using Cellebrite UFED and Magnet AXIOM, a significant number of artifacts were accurately recovered mainly from the “GroupMe.sqlite” and “GroupMe.sqlite-wal” databases. Out of the 335 artifacts populated on the iPhone, 317 were correctly recovered by both UFED and AXIOM, resulting in an accuracy of 94.62%. No GroupMe related artifacts could be recovered from the Android device. This was due to several physical imaging and rooting limitations imposed by the Samsung SM-935A model, which was used during the study.

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The demand for ultra-high-speed machines (UHSM) is rapidly growing in high-tech industries due to their attractive features. A-mechanically-based-antenna (AMEBA) system is another emerging application of UHSM. It enables portable wireless communication in the radio frequency (RF)-denied environment, which was not possible until recently. The AMEBA system requires a high-power (HP) UHSM for its effective communication performance. However, at the expected rotational speed range of 0.5 to 1 million rpm, the power level of UHSM is limited, and no research effort has succeeded to improve the power level of UHSM. The design of HP-UHSM is highly iterative, and it presents several critical challenges, unlike low-power UHSM, such as critical-bending-resonance (CBR), strong mutual influence among Multiphysics performances, exponential air-friction loss, and material limitation. When the magnetic loading of the UHSM rotor is increased to improve the power level, the rotor experiences serious mechanical vibration due to the excessive centrifugal forces and CBR. This vibration limits the operation of HP-UHSM and leads to structural breakdown. Furthermore, the design process becomes more critical when it considers the multidisciplinary design constraints and application requirements. This dissertation proposed a new Multiphysics design method to develop HP-UHSM for critical applications. First, the critical design constraints which prevent increasing the output power of UHSM are investigated. Then, a Multiphysics optimization model is developed by coupling several multidisciplinary analysis modules. This proposed optimization model enables (i) defining multidisciplinary design constraints, (ii) consideration of Multiphysics mutual influence, and (iii) a trade-off analysis between the efficiency and design-safety-margin. The proposed design model adopts the multiphase winding system to effectively increase the electrical loading in the slotless stator. Finally, a 2000 W 500,000 rpm HP-UHSM is optimized for an AMEBA system using the proposed design method. The optimized 2 kW 500,000 rpm machine prototype and its dynamo setup are built in the laboratory. Extensive finite element simulations and experimental testing results are presented to validate the effectiveness of the proposed design method. The results show that the proposed HP-USHM has 94.5% efficiency, 47 kW/L power density, 30% global design safety margin at the maximum speed and no CBR frequency below 11 kHz.

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)