In traditional aircraft conceptual design, subsystems are largely accounted for implicitly based on available historical data and trends. Such an approach has limitations when novel subsystem architectures such as More Electric or All Electric aircraft are considered, since historical data regarding such architectures is either limited or non-existent. In such cases, the incorporation of more thorough and explicit consideration of the aircraft subsystems into the conceptual design phase is warranted. The first objective of this dissertation is to integrate subsystem sizing and analysis methods that are suitable for the early design phases with the traditional aircraft sizing methodology. The goal is to facilitate the assessment subsystem architecture performance with respect to vehicle and mission level metrics. The second objective is to investigate how the performance of different subsystem architectures varies with aircraft size. The third and final objective is to assess the sensitivity of architecture performance to epistemic and technological uncertainty. These objectives are pursued through the development of an integrated sizing and analysis environment where the subsystems are sized in parallel with the aircraft itself using subsystem models that are computationally inexpensive and do not require detailed aircraft definition. The effects of subsystem mass, secondary power requirements, and drag increments are propagated to the mission performance analysis following which the vehicle and subsystems are re-sized. A number of experiments are performed to first test the capabilities of the developed environment and subsequently assess the performance of numerous subsystem architectures and the sensitivity of select architectures to epistemic and technological uncertainty.

Dagens samhälle har utvecklats till ett stort globalt system där människan fått en signifikant påverkan på klimatet och miljön. För att nå målet i Parisavtalet är det många sektorer som behöver ställa om sina verksamheter till att bli hållbara. Det gäller i allra högsta grad flygsektorn som har stora utmaningar framför sig när det gäller att minska sitt klimatavtryck. En av möjligheterna för att väsentligt minska flygets klimatpåverkan är att övergå till flygplan som drivs med hjälp av batterier istället för fossila bränslen.I det här projektet undersöks om de tekniska och infrastrukturmässiga förutsättningarna finns för att elflyg ska kunna ersätta den befintliga flygtrafiken mellan Stockholm och Visby och när i tiden en sådan förändring kan ske. Litteraturstudier och intervjuer har använts för att utforska det nuvarande kunskapsläget som är relevant för elflyg inom batteriteknik, elmotorer, aerodynamik samt infrastruktur på de relevanta flygplatserna. Med den utgångspunkten har en matematisk modell använts för att studera om de rådande tekniska förutsättningarna är tillräckliga eller om förbättringar kommer krävas. Det som framkom var att det i teorin är möjligt att tillverka ett elflygplan som kan flyga hela sträckan med befintlig teknik men att utveckling av både batteriteknik och aerodynamik sannolikt kommer krävas när andra aspekter vägs in. Infrastrukturen på flygplatserna är dessutom inte anpassade för elflyg i dagsläget, vilket leder till att det i ett optimistiskt scenario kommer gå att elektrifiera flygtrafiken mellan Stockholm och Visby inom 10 år. / Today's society has evolved into a large global system where people have a significant impact on the climate and the environment. To achieve the goal of the Paris Agreement, many sectors need to change their business to become sustainable. This is very much the case for the aviation sector, which has major challenges ahead when it comes to reducing its climate footprint. One of the opportunities to significantly reduce the climate impact of aviation is to switch to aircraft powered by batteries instead of fossil fuels. This project examines whether the technical and infrastructure conditions are in place for electric aircraft to replace the existing air traffic between Stockholm and Visby and when such a change can occur in time. Literature studies and interviews have been used to explore the current state of knowledge relevant to electric aviation within battery technology, electric motors, aerodynamics and infrastructure at the relevant airports. Based on this, a mathematical model has been used to study whether the current technical conditions are sufficient or if improvements will be required. What emerged was that, in theory, it is possible to produce an electric aircraft that can fly the entire distance with existing technology, but that development of both battery technology and aerodynamics is likely to be required when other aspects are taken into account. The infrastructure at the airports is also not adapted for electric flights yet, which means that in an optimistic scenario it will take up to 10 years before air traffic can be fully electrified between Stockholm and Visby.

No description available.

The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet. / Doctor of Philosophy / The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet.

With the rapid growth of air travel, concerns about the emissions of greenhouse gas emissions resulting from the air transportation sector are growing. Although the current battery technologies might not be adequate for all-electric regional aircraft, the energy density of the current battery technologies could be adequate to electrify light-sport aircraft used for training and recreation. Due to the nature of the propeller load and noise isolation of the cabin, switched reluctance motors can be an excellent candidate for the propulsion system of electrified light-sport aircraft. The proposed SRM is designed to replace a 70 kW permanent magnet synchronous motor used in the aerospace industry with similar volume constraints and operational requirements. In order to meet the high-power density requirements of this application, a design framework is proposed which includes several layers of the design process. The design objectifies are the average torque, torque ripple, and radial forces by integrating the control and geometry design into the proposed framework. A comprehensive design process is carried out with the proposed framework, and a detailed coil design process is performed. The rotor cut-outs are designed to reduce the weight of the motor. The thermal performance of the motor has been analyzed for the calculated motor losses and the cooling system constraints. / Thesis / Master of Applied Science (MASc)