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<p>  </p> <p>With rising concerns over commercial aviation’s contribution to global carbon emissions, there exists a tremendous pressure on the aviation industry to find advanced technological solutions to reduce its share of CO2 emissions. Single-aisle (or narrowbody) aircraft are the biggest contributors to CO2 emissions by number of operations, insisting a need to reduce / eliminate their aircraft-level fuel consumption as soon as possible. A potential solution for this is to operate fully-electric single-aisle aircraft; however, the limitations of the current (and predicted future) battery technology is forcing the industry to explore hybrid-electric aircraft as a possible mid-term solution.</p> <p>Modeling hybrid-electric aircraft comes with its own challenges due to the presence of two different propulsion sources – gas turbine engines (powered by Jet-A fuel) and electric motors (powered by batteries). Since traditional sizing approaches and legacy sizing tools do not seem to work well for hybrid-electric aircraft, this work presents a “flight-mechanics-based” conceptual sizing tool for hybrid-electric aircraft, set up as a Multidisciplinary Design Optimization (MDO) toolbox. Some of the key features of the sizing tool include concurrently sizing the electric motors and downsizing the gas turbine engines while meeting the one-engine-inoperative (OEI) and top-of-climb constraints, and re-sizing the fuselage to account for the volumetric constraints associated with required batteries.</p> <p>Current work considers a parallel hybrid-electric single-aisle aircraft with a 900 nmi design range, with electric power augmentation (with electric motors operating at full throttle) available only for the takeoff and climb segments when sizing the aircraft. Four hybrid-electric propulsion technology cases are considered, and the resulting hybrid-electric aircraft show 15.0% to 22.5% reduction in fuel burn compared to a Boeing 737-800 aircraft.</p> <p>Another challenge with modeling hybrid-electric aircraft is determining their off-design performance characteristics (considering a different payload or mission range, or both). This work presents an energy management tool – set up as a nonlinear programming optimization problem – to minimize the fuel burn for a payload-range combination by identifying the optimal combination of throttle settings for the gas turbine engines and the electric motors during takeoff, climb, and cruise, along with identifying an optimal flight path. The energy management tool enables fuel savings of at least of 2%, with actual savings ranging from 142.1 lbs to 276.1 lbs per trip for a sample route (LGA–ORD) at a 80% load factor.</p> <p>Although the hybrid-electric aircraft sizing and performance analysis studies show encouraging results about the potential reduction in carbon emissions at an aircraft level, the future fleet-level carbon emissions are not expected to reduce proportionally to these aircraft level emission reductions. This work predicts the fleet-level environmental impacts of future single-aisle parallel hybrid-electric aircraft by modeling the behavior of a profit-seeking airline (with a mixture of conventional all Jet-A fuel burning and hybrid electric aircraft in its fleet) using the Fleet-Level Environmental Evaluation Tool (FLEET). FLEET’s model-based predictions rely upon historically-based information about US-touching airline routes and passenger demand served by US flag-carrier airlines from the Bureau of Transportation Statistics to initiate model-based predictions of future demand, aircraft fleet mix, and aircraft operations. Using the aircraft performance coefficients from the energy management tool to represent the behavior of a single-aisle parallel hybrid-electric aircraft, the FLEET simulation predicts the changes in the fleet-wide carbon emissions due to the introduction of this new aircraft in an airline fleet in the year 2035. By 2055, FLEET results predict that the fleet-wide CO2 emissions with hybrid-electric aircraft in the fleet mix are at least 1.2% lower than the fleet-wide CO2 emissions of a conventional (all Jet-A fuel burning) aircraft-only airline. The rather limited reduction in emissions is an attribute of the reduced range capability and higher operating cost of the hybrid-electric aircraft (relative to a conventional aircraft of similar size). This causes the airline to change the usage, acquisition and retirement of its conventional aircraft when hybrid-electric aircraft are available; this is most notable to serve passenger demand on certain predominantly single-aisle service routes that cannot be flown by the future single-aisle hybrid-electric aircraft. </p>

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This master thesis will be part of a larger project called Sustainable Energy Transition in Aviation (SETA), which will be done in collaboration with the Division of Sustainability, Industrial Dynamics and Entrepreneurship (SIDE) at INDEK. The overall thesis aims to contribute to accelerate the energy transition within the aviation sector, with a focus on three technologies: bio-based jet fuels, hydrogen fuels and electrical aircraft. Moving on, this research project is being pursued because aviation is one of the most important CO2 emitters in Sweden. Indeed it accounts for 5% of total Swedish emissions (Klimatpolitiska Rådet, 2020). Due to its complexity as a socio technical system and its tight interrelations between its components, aviation is struggling to change. Therefore, a transformative pressure is raising in order to meet 2030 and 2045 targets. The aim of the research is to highlight how the introduction of alternative fuels and technologies might help aviation to reach carbon neutrality. Moreover, the aviation industry could be classified as a socio-technical system, thereby a conceptual framework was used to better analyze its transition. The Multi-Level Perspective framework (MLP) was thus applied with the intent of describing how the sustainable energy transformation will happen at the different levels. Through interviews it was possible to underline the different challenges within the aviation system, while also highlighting future scenarios of the air transport sector. Furthermore, by developing a modelling analysis through the LEAP software, it was possible to hypothesized several scenarios where biofuels, hydrogen and electric airplanes growth varies under specific assumptions. Finally, the analysis highlighted that the introduction of these alternative technologies will be crucial to support aviation in its green transformation. Indeed, between year 2015 and 2045, the total emissions from the analyzed transport sector were reduced by 90%. Therefore, aviation will essentially need these new technologies in order to transform and become greener. / Detta examensarbete kommer att ingå i ett större projekt som heter Sustainable Energy Transition in Aviation (SETA), vilket kommer att göras i samarbete med avdelningen för hållbarhet, industriell dynamik och entreprenörskap (SIDE) vid INDEK. Den övergripande avhandlingen syftar till att bidra till att påskynda energiövergången inom flygsektorn, med fokus på tre tekniker: biobaserade jetbränslen, vätgasbränslen och elektriska flygplan. Detta forskningsprojekt pågår eftersom luftfarten skapar stora mängder koldioxidutsläpp i Sverige. Det står för 5% av de totala svenska utsläppen (Klimatpolitiska Rådet, 2020). På grund av dess komplexitet som ett sociotekniskt system och dess snäva samband mellan komponenter, kämpar luftfarten för att förändras. Därför ökar ett transformerande tryck för att nå 2030 och 2045 mål. Syftet med forskningen är att belysa hur införandet av alternativa bränslen och tekniker kan hjälpa luftfarten att nå koldioxidneutralitet. Dessutom kan flygindustrin klassificeras som ett socio-tekniskt system, varigenom en konceptuell ram användes för att bättre analysera dess övergång. Multi-Level Perspective Framework (MLP) tillämpades således med avsikten att beskriva hur den hållbara energiomvandlingen kommer att ske på de olika nivåerna. Genom intervjuer var det möjligt att ta fram de olika utmaningarna inom flygsystemet, samtidigt som man framhävde framtida scenarier inom lufttransportsektorn. Genom att utveckla en modelleringsanalys genom LEAPprogramvaran var det dessutom möjligt att hypotisera flera scenarier där biodrivmedel, väte och elektriska flygplanstillväxt varierar under specifika antaganden. Slutligen visade analysen att införandet av dessa alternativa tekniker kommer att vara avgörande för att stödja luftfarten i dess gröna omvandling. Mellan 2015 och 2045 minskade de totala utsläppen från den analyserade transportsektorn med 90%. Därför kommer luftfarten i huvudsak att behöva dessa nya tekniker för att förändras och bli grönare.

In light of rising environmental concerns, and with governments world-wide legislating for drastic GHG emission reductions, the aviation industry, being an important contributor to global warming, is facing strong pressures to transform. However, given the social and economic relevance of aviation as rapid transport method and an enabler of globalization, a reduction in aviation emissions is unlikely to come from reduced air transport. Instead, three aviation technologies have received increased attention within the literature for their potential to account for high emission reductions in the coming decades: biofuels, electric and hydrogen aircraft. Countries worldwide have committed to ambitious climate goals. Sweden, for example, is expecting to become fossil-free by 2045. However, are airports already preparing for the adoption of these technologies? What factors can help airports transform in this environmental transition? Is there something to be learnt from the early adopters? The present report draws information from a survey to Swedish commercial airports, and a round of interviews with industry experts, in order to shed light on these questions. By mapping the progress of airports through the survey, and analyzing its results using the Diffussion of Innovation Theory, it is possible to draw conclusions on how much progress airports in the Swedish context have made. Additionally, by collecting interview results and analyzing them through the Multi-level perspective, it is possible to understand the factors that favoured the adoption of new technologies by these leading airports. / Mot bakgrund en ökande oro för miljön, lagstiftar regeringar världen över om drastiska minskningar av utsläppen av växthusgaser. Flygindustrin, som är en viktig bidragande orsak till den globala uppvärmningen, står inför starka påtryckningar att ställa om. Med tanke på flygets sociala och ekonomiska betydelse är det dock osannolikt att en minskning av flygets utsläpp kommer att ske genom minskade flygtransporter. Istället har ny teknik för att minska flygets miljöpåverkan fått ökad uppmärksamhet i litteraturen. Tre föreslagna tekniker kan ha potential att avsevärt minska utsläppen av växthusgaser under de kommande decennierna: biodrivmedel, samt el- och vätgasdrivna flygplan. Sverige har antagit ambitiösa klimatmål och räknar med att bli fossilfritt 2045. Men har flygplatserna ännu börjat förbereda sig för att införa någon av teknikerna ovan? Vilka faktorer kan hjälpa flygplatserna i denna övergång och finns det något att lära av de tidiga användarna? Denna rapport bygger på en undersökning av ett antal svenska flygplatser och intervjuer med branschexperter. Genom att plotta de undersökta flygplatsernas svar med hjälp av Diffussion of Innovation Theory - DOI, är det möjligt att dra slutsatser om hur långt de svenska flygplatserna har kommit i sin omställning. Genom att analysera intervjuresultaten med hjälp av flernivåperspektivet MLP är det dessutom möjligt att förstå vilka faktorer som gynnade införandet av ny teknik på dessa flygplatser.

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)

Ces travaux de thèse s’inscrivent dans la problématique de développement de transformateurs planar pour l’intégration de puissance, dans le contexte de l’avion plus électrique (More Electric Aircraft – MEA) où les contraintes de volume et de poids sont primordiales. Les composants magnétiques restent en effet un frein à l’intégration des systèmes d’Electronique de Puissance et les composants planar (transformateurs et inductances) offrent une alternative intéressante aux composants bobinés pour la réduction de la taille des convertisseurs.Dans ce manuscrit, des méthodes, un outil de dimensionnement et des prototypes de transformateurs planar (2 et 3 enroulements) en technologie feuillard et PCB sont développés pour des applications de convertisseur DC/DC aéronautique. Dans un premier temps, les modèles permettant le calcul des pertes, l'estimation de l'élévation de température et le calcul de l’inductance de fuite sont présentés et comparés afin de concevoir des outils de calculs pour la conception. Dans un deuxième temps, il est montré que la modification de la forme des angles des spires rectangulaires permet de réduire significativement les pertes cuivre HF. Sur la base de ces outils et résultats, des prototypes de transformateurs planar à 3 enroulements en PCB multicouches sont développés. De nombreux prototypes sont caractérisés et valident les modèles de dimensionnement proposés. Enfin, l’un de ces prototypes est intégré et testé dans un convertisseur de puissance DC/DC de 3.75kW mettant en évidence les gains obtenus. / These thesis works deal with the issue of the planar transformers development for power integration, in the context of the More Electric Aircraft (MEA), where the constraints of volume and weight are paramount. Magnetic components remain a hindrance to the integration of Power Electronics systems and planar components (transformers and inductors) offer an interesting alternative to wound components for reducing the size of converters.In these works, methods, a sizing tool and prototypes of planar transformers (2 and 3 windings) in strip and PCB technology are developed for aeronautical DC / DC converter applications. Firstly, the models allowing the calculation of the losses, the estimation of the temperature rise and the calculation of the leakage inductance are presented and compared in order to design calculation tools for engineers. In a second step, it is shown that the modification of the shape of the angles of rectangular turns makes it possible to significantly reduce the HF copper losses.Based on these tools and results, prototypes of 3-windings planar transformers in multilayer PCBs are developed. Many prototypes are characterized and validate the proposed designing models. Finally, one of these prototypes is integrated and tested in a DC / DC power converter of 3.75kW highlighting the gains obtained.

Depuis des années, les avionneurs sont engagés pour la réduction de l’empreinte environnementale à travers le développement de nouveaux concepts. Ainsi, le remplacement des systèmes hydrauliques (hydraulicless) et pneumatiques (bleedless) de l’avion par des systèmes électriques sont envisagés d’où l’apparition du concept d’avion « plus électrique ». Toutefois, les gains espérés (diminution du coût, de la consommation de carburant ou de la masse) suite à cette substitution ne sont pas si faciles à obtenir, car les technologies précédentes ont bénéficié de plusieurs dizaines d’années de développement et d’optimisation. Les solutions électriques nouvellement proposées doivent donc elles aussi être très abouties pour être véritablement concurrentielles ; tous les degrés de liberté doivent être envisagés, qu’il s’agisse des technologies ou des architectures. En particulier, l’usage d’un nouveau réseau HVDC (540 V) semble être une solution prometteuse. A partir de ce réseau HVDC, les différentes charges AC triphasées sont alimentées par une série d’onduleurs génériques. Compte tenu de la disparité des consommations pendant les différentes phases de vol, le même onduleur peut servir à alimenter plusieurs charges. La connexion entre les onduleurs et les charges est gérée par une matrice de contacteurs. Cette solution innovante considère également des cas de redondance pour augmenter la robustesse de la solution. La conception de ce nouveau système est présentée dans ce rapport de thèse. Le compromis optimal entre le nombre d’onduleurs et la puissance nominale de chaque onduleur doit être obtenu. Ce choix déterminera fortement la taille de la matrice de contacteurs. Cependant, pour adresser cette problématique, il est nécessaire de connaître la masse des différents composants en fonction de la puissance requise. Un environnement de conception est ainsi créé dans le but de réaliser le dimensionnement optimal de convertisseurs de puissance. Les différents composants sont décrits utilisant une approche « directe » et sont codés sous le formalisme « orienté-objet ». Ces modèles sont ensuite validés expérimentalement ou par simulation numérique. Les différents modèles sont couplés à un environnement d’optimisation et à un solveur fréquentiel qui permet une résolution rapide des formes d’ondes du régime permanent. L’environnement d’optimisation réalise le dimensionnement précis des différentes parties de l’onduleur : dissipateur, module de puissance, filtre côté continu et inductance de couplage. Un onduleur est proposé pour différentes puissances nominales et fréquences de découpage. L’optimisation adresse également le choix des différentes technologies. Finalement, les résultats sont utilisés pour déterminer le meilleur compromis entre nombre d’onduleurs et puissance de l’onduleur à partir d’un algorithme heuristique. / In recent years, aircraft manufacturers have been making progress in the design of more efficient aircrafts to reduce the environmental footprint. To attain this target, aircrafts manufactures work on the replacement of the hydraulic and bleed systems for electrical systems leading to a “More Electrical Aircraft”. However, the expected mass gain is a challenge, as previous technologies have been developed and optimized for decades. The new electrical solutions need to be look into detail to be competitive with previous technologies. All degrees of freedom must be considered, that is, new technologies and architectures. In particular, an HVDC network that reduces the number of rectifier stages seems a promising solution. From the HVDC network, the different three phase AC loads will be supplied by a series of power generic inverters. As the power consumption of the different loads change during the flight mission, the same inverter is used to supply different loads. The connection between the inverters and the loads is managed by a matrix of contactors. The proposed solution also considers redundant configurations, thus increasing system robustness. The design of the innovative system is presented in this document. That is, determining the optimal trade-off between the number of power inverters and the nominal power of each generic inverter that will also impact the size of the matrix of contactors. However, to assess the combinatory problem, the mass of the different components as a function of the nominal power needs to be calculated. A design environment is therefore created to perform automatic and optimized design of power converters. The different components are described using a “direct modelling” approach and coded using “object-oriented” programming. The components are validated experimentally or by numerical simulations. The different models are coupled to an optimization environment and to a frequency solver allowing a fast calculation of the steady-state waveforms. The optimization environment performs the precise design of the different parts of the power inverter: heatsink, power module, DC filter and coupling inductor. The power inverter is designed for different values of nominal power and switching frequency. The optimization assesses as well the usage of different technologies. Finally, the results are used to determine the optimal trade-off between the number of inverters and the nominal power of each inverter using a heuristic algorithm.

Dans le contexte de l'avion plus électrique, de nouveaux défis technologiques apparaissent dans le développement des systèmes embarqués afin d'augmenter leur puissance électrique. Une optimisation visant la sécurité, l'efficacité énergétique et une diminution du volume et de la masse est ainsi nécessaire. A cet effet, les dispositifs doivent être considérés dans leur ensemble et non par éléments séparés. Pour faciliter l'intégration des systèmes de puissance et assurer la qualité du réseau de bord avion, cette thèse propose de tenir compte de la mission de vol et d'étudier la CIO « Conception Intégrée Optimale » du système complet comprenant le filtre d'entrée et l’onduleur de tension alimentant l'actionneur synchrone à aimants permanents haute vitesse « HSPMSM ». L'application est dédiée au système de conditionnement d'air cabine « ECS – Environmental Conditioning Systems » comprenant le compresseur d'air étudié, d'une puissance nominale de 70 kW. La thèse est structurée en trois parties principales: le dimensionnement des composants de la chaîne de conversion électromécanique ; la conception locale et séquentielle de chacun des composants du système (boucle d'optimisation actionneur puis boucle d'optimisation « onduleur de tension + filtre d'entrée » ; la conception simultanée de tous les composants du système (boucle d'optimisation globale). Les fronts « Pareto-optimaux » des solutions obtenues à partir des méthodes de conception séquentielles et simultanées sont présentés, analysés et comparés. Les résultats mettent clairement en évidence l'avantage d'utiliser une boucle d'optimisation unique pour l'amélioration de la masse et de l'efficacité énergétique du système. / The concept of More Electric Aircraft (MEA) implies new challenges especially due to the increase of the electrical embedded power. By this way, necessary improvements in terms of safety, energy efficiency and weight reduction are required. For this reason, the design of devices should be more approached with a view to the whole system than as separated elements. In order to facilitate power system integration and to ensure power quality aboard, this dissertation proposes an Integrated Optimal Design (IOD) of the input filter and the inverter feeding the High Speed Permanent Magnet Synchronous Motor (HSPMSM) by taking the flight mission into account. The Environmental Conditioning System (ECS) is equipped of the studied cabin air compressor with a rated power of 70 kW: a Multiobjective Genetic Algorithm (MOGA) is applied to achieve the CIO process. Considering the ECS as a whole, this thesis can be divided into three main parts: components sizing of the electromechanical conversion chain; local and sequential design of each system components (HSPMSM optimization loop followed by “voltage source inverter + input filter” optimization loop); simultaneous design of all system components (global optimization loop). Pareto-optimal solutions obtained from sequential and simultaneous design approaches are presented, analyzed and compared. Results clearly highlight the advantage of using a single optimization loop for the whole system in order to improve mass and efficiency.

Dans le domaine de l'aéronautique, les concepts basés sur l’usage étendu de l'électricité dans les aéronefs plus électriques (MEA) et même tout électriques (AEA) font appel à des actionneurs électromécaniques (EMA) en replacement des actionneurs servo-hydrauliques conventionnels (HSA). Lorsque les EMA sont utilisés pour des applications d'actionnement critique comme les commandes de vol, certains problèmes spécifiques liés à l’équilibre thermique, l'inertie réfléchie, le mouvement parasite dû aux élasticités structurelles, la réponse aux fautes (grippage et rupture) et la synchronisation d’EMA actifs sur charges indépendantes ne peuvent être ignorés. La simulation apporte un support indéniable à la conception pour l’évaluation et la validation des concepts. A cet effet, il est nécessaire de développer des prototypes virtuels des EMA avec une vision système et de façon structurée pour répondre aux besoins des ingénieurs. Malheureusement, les phénomènes physiques qui apparaissent dans les EMA sont multidisciplinaires, couplés et fortement non linéaires. De nombreux logiciels commerciaux de simulation système multi-domaines sont désormais disponibles. Cependant, le processus de modélisation et les besoins des ingénieurs sont rarement pris en compte selon une vision globale, en raison du manque d'approches scientifiques pour la définition d’architectures, la modélisation incrémentale et l’amélioration de l’implémentation numérique des modèles. Dans cette thèse, le prototypage virtuel de l'EMA est adressé en utilisant le formalisme Bond-Graph. De nouvelles approches sont proposées pour permettre la modélisation incrémentale de l'EMA en vue de fournir des modèles pour la synthèse de la commande, l’évaluation de la consommation d'énergie, l'analyse thermique, le calcul des forces de réaction, la simulation de la pollution du réseau d'alimentation électrique, la réponse aux fautes et l'influence de la température. L’intérêt des modèles proposés est illustré sur l’exemple de la synchronisation de position de deux EMA actionnant des charges indépendantes. / In the aerospace field, the concepts based on extended use of electricity in “More Electric Aircraft” (MEA) and even “All Electric Aircraft” (AEA), involve electromechanical actuators (EMAs) to replace conventional hydraulic servo actuators (HSAs). When EMAs are used for safety-critical actuation applications like flight controls, some specific issues related to thermal balance, reflected inertia, parasitic motion due to compliance, response to failure (jamming and free-run) and synchronization of EMAs driving independent loads cannot be ignored. The simulation-aided design process can efficiently support the assessment and validation of the concepts fixing these issues. For that, virtual prototypes of EMAs at system-level have to be developed in a structured way that meets the engineers’ needs. Unfortunately, the physical effects governing the EMAs behavior are multidisciplinary, coupled and highly nonlinear. Although numerous multi-domain and system-level simulation packages are now available in the market of simulation software, the modelling process and the engineers’ needs are rarely addressed as a whole because of lack of scientific approaches for model-based architecting, multi-purpose incremental modelling and model implementation for efficient numerical simulation. In this thesis, the virtual prototyping of EMAs is addressed using the Bond-Graph formalism. New approaches are proposed to enable incremental modelling of EMAs that provides models supporting control design, energy consumption and thermal analysis, calculation of reaction forces, power network pollution simulation, prediction of response to faults and influence of temperature. The case of preliminary design of EMAs position synchronization is used to highlight the interests and advantages of the proposed process and models of EMAs.