Ces travaux portent sur la question de l’autonomie énergétiquedes capteurs sans fil dans un contexte aéronautique, à laquelle la récupérationet le stockage d’énergie ambiante sont susceptibles d’apporter uneréponse. Nous étudions dans un premier temps la génération thermoélectrique,destinée à être appliquée au suivi du vieillissement structurelprès de la zone moteur, et débouchant sur la réalisation d’un démonstrateur.Nous proposons ensuite une architecture de stockage capacitif qui,en s’adaptant à son état de charge, vise à améliorer la performance de cettesolution de stockage en termes de temps de démarrage, de taux d’utilisationd’énergie et sous certaines conditions, de transfert d’énergie. Finalement,nous rapportons les résultats d’une étude prospective sur la récupérationd’énergie du vent relatif grâce au phénomène aéroacoustique. Nousmontrons que cette méthode présente un potentiel énergétique intéressant,puis nous présentons la conception et la réalisation d’un circuit optimiséde gestion de l’énergie, permettant d’alimenter grâce à cette technique uncapteur sans fil de température / This work adresses the issue of energy autonomy within wirelesssensor networks embedded in aircrafts, which may be solved throughambient energy harvesting and storage. In a first study, we develop a demonstratorbased on thermal gradients energy harvesting, which is designedto supply power to a structural health monitoring system implementednear the engine zone. Thereafter, we introduce a capacitive storagearchitecture which self-adapts to its own state of charge, aiming at improvingits performance in terms of startup time, the energy utilization ratioand under some conditions, the energy transfer. Finally, we report the resultsof a prospective study on aeroacoustic energy harvesting appliedto the relative wind. It is shown that this method exhibits an interestingpotential in terms of generated power, then we introduce the design andthe realization of an optimized energy management circuit, allowing ourtechnique to supply power to a wireless temperature sensor

L'électronique a connu une évolution incontestable ces dernières années. Les progrès réalisés, notamment dans l'électronique numérique et l'intégration des circuits, ont abouti à des systèmes plus performants, miniatures et à faible consommation énergétique. Les évolutions technologiques, alliant les avancées de l'informatique et des technologies numériques et leur intégration de plus en plus poussée au sein d'objets multiples, ont permis le développement d'un nouveau paradigme de systèmes qualifiés de systèmes cyber-physiques. Ces systèmes sont massivement déployés de nos jours grâce à l'expansion des applications liées à l'Internet Des Objets (IDO). Les systèmes cyber-physiques s'appuient, entre autre, sur le déploiement massif de capteurs communicants sans fil autonomes, ceux-ci présentent plusieurs avantages : * Flexibilité dans le choix de l'emplacement. Ils permettent l'accès à des zones dangereuses ou difficiles d'accès. * Affranchissement des câbles qui présentent un poids, un encombrement et un coût supplémentaire. * Elimination des problèmes relatifs aux câbles (usure, étanchéité...) * Facilité de déploiement de réseaux de capteurs Cependant, ces capteurs sans fils nécessitent une autonomie énergétique afin de fonctionner. Les techniques conventionnelles telles que les batteries ou les piles, n'assurent le fonctionnement des capteurs que pour une durée limitée et nécessitent un changement périodique. Ceci présente un obstacle dans le cas où les capteurs sans fils sont placés dans un endroit où l'accès est impossible. Il est donc nécessaire de trouver un autre moyen d'approvisionner l'énergie de façon permanente à ces réseaux de capteurs sans fil. L'intégration et la miniaturisation des systèmes électroniques ont permis la réalisation de systèmes à faible consommation, ce qui a fait apparaître d'autres techniques en termes d'apports énergétiques. Parmi ces possibilités se trouvent la récupération d'énergie électromagnétique et le transfert d'énergie sans fil (TESF). En effet, l'énergie électromagnétique est de nos jours, omniprésente sur notre planète, l'utiliser donc comme source d'énergie pour les systèmes électroniques semble être une idée plausible et réalisable. Cette thèse s'inscrit dans ce cadre, elle a pour objectif la conception et la fabrication de systèmes de récupération d'énergie électromagnétique pour l'alimentation de réseaux de capteurs sans fil. Le circuit de récupération d'énergie électromagnétique est appelé " Rectenna ", ce mot est l'association de deux entités qui sont " antenne " et " rectifier " qui désigne en anglais le " redresseur ". L'antenne permet de récupérer l'énergie électromagnétique ambiante et le redresseur la convertit en un signal continu (DC) qui servira par la suite à alimenter les capteurs sans fil. Dans ce manuscrit, plusieurs rectennas seront présentées, pour des fréquences allant des bandes GSM 868MHz, 915MHz, passant par l'UMTS à 2GHZ et WIFI à 2,45GHz, et allant jusqu'aux bandes Ku et Ka. / The electronic domain has known a significant expansion the last decades, all the advancements made has led to the development of miniature and efficient electronic devices used in many applications such as cyber physical systems. These systems use low-power wireless sensors for: detection, monitoring and so on. The use of wireless sensors has many advantages: * The flexibility of their location, they allow the access to hazardous areas. * The realization of lighter system, less expensive and less cumbersome. * The elimination of all the problems associated to the cables (erosion, impermeability...) * The deployment of sensor arrays. Therefore, these wireless sensors need to be supplied somehow with energy to be able to function properly. The classic ways of supplying energy such as batteries have some drawbacks, they are limited in energy and must be replaced periodically, and this is not conceivable for applications where the wireless sensor is placed in hazardous places or in places where the access is impossible. So, it is necessary to find another way to permanently provide energy to these wireless sensors. The integration and miniaturization of the electronic devices has led to low power consumption systems, which opens a way to another techniques in terms of providing energy. Amongst the possibilities, we can find the Wireless Power Transfer (WPT) and Energy Harvesting (EH). In fact, the electromagnetic energy is nowadays highly available in our planet thanks to all the applications that use wireless systems. We can take advantage of this massive available quantity of energy and use it to power-up the low power wireless sensors. This thesis is incorporated within the framework of WPT and EH. Its objective is the conception and realization of electromagnetic energy harvesters called "Rectenna" in order to supply energy to low power wireless sensors. The term "rectenna" is the combination of two words: Antenna and Rectifier. The Antenna is the module that captures the electromagnetic ambient energy and converts it to a RF signal, the rectifier is the RF circuit that converts this RF signal into a continuous (DC) signal that is used to supply the wireless sensors. In this manuscript, several rectennas will be presented, for different frequencies going from the GSM frequencies (868 MHz, 915 MHz) to the Ku/Ka bands.

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This thesis is based around the use of energy harvesting in systems, specifically for a Bluetooth Low Energy (BLE) mesh testbed. This BLE mesh is located in a well lit lab and is currently powered by mains electricity. Systems such as the BLE mesh are considered Internet of Things (IoT). The market for these systems is rapidly expanding and in turn so is the energy use. Many systems are powered by battery, and the need to replace a battery with an energy harvesting system has arisen. This thesis will explore the possibilities to power a node in this mesh and introduce a level of intelligence to allow the system to better predict available energy to harvest. The lab the BLE mesh is in is characterised for potential energy sources. Light is chosen to be an exceptional power source, from here a lux metre is created from a photovoltaic (PV) cell. This PV cell would function as both the power for the system and provide a method to measure the current light intensity. This would help add a layer of intelligence to the system to allow future systems to better understand how much energy is available. This idea can be implemented in other harvesters as well. / Denna avhandling är baserad på användningen av energiskördning i ett system, specifikt i en Bluetooth Low Energy (BLE)-mesh. Denna BLE-mesh befinner sig i ett väl upplyst labb och är för närvarande strömdrivet genom huvudström. System som BLE-mesh anses vara en del av Internet of Things (IoT). Marknaden för dessa system expanderar snabbt och därmed ökar också energiförbrukningen. Många system är batteridrivna och det har uppstått ett växande behov av att ersätta batteriet med ett energiskördsystem. Denna avhandling kommer att utforska möjligheterna att strömförsörja en nod i denna mesh och införa en intelligensnivå för att förbättra systemets möjlighet att förutspå energi som är tillgänglig för att skördas. Labbet där BLE-meshen befinner sig karakteriseras för potentiella energikällor. Ljus valdes som en exceptionell kraftkälla, och därifrån skapas en luxmeter från en fotovoltaisk (PV) cell. Denna PV-cell ska fungera både som strömkälla för systemet och utgöra en metod för att mäta nuvarande ljusintensitet. Detta skulle bidra till att lägga till ett skikt av intelligens i systemet för att göra det möjligt för framtida system att bättre förutspå tillgänglig skördbar energi. Denna idé kan även implementeras i andra energiskördsystem.

Internet of Things (IoT) is becoming a more and more prevailing technology, as it not only makes the routine of our life easier, but it also helps industry and enteprise become more efficient. The high potential of IoT can also help support our own population on Earth, through precision agriculture, smart transportation, smart city and so on. It is therefore important that IoT is made scalable in a sustainable manner, in order to secure our own future as well.The current work is concerning transiently powered systems (TPS), which are embedded systems that use energy harvesting as their only power source. In their basic form, TPS suffer frequent reboots due to unreliable availability of energy from the environment. Initially, the throughput of such systems are therefore lower than their battery-enabled counterparts. To improve this, TPS involve checkpointing of RAM and processor state to non-volatile memory, as to keep computation progress saved throughout power loss intervals.The aim of this project is to lower the number of checkpoints necessary during an application run on a TPS in the generic case, by using approximate computing. The energy need of TPS is lowered using approximations, meaning more results are coming through when the system is working between power loss periods. For this study, the memoization technique is implemented in the form of a hash table. The Kalman filter is taken as the testing application of choice, to run on the Microchip SAM-L11 embedded platform.The memoization technique manages to yield an improvement for the Kalman application considered, versus the initial baseline version of the program. A user is allowed to ”balance” between more energy savings but more inaccurate results or the opposite, by adjusting a ”quality knob” variable epsilon ϵ.For example, for an epsilon ϵ = 0.7, the improvement is of 32% fewer checkpoints needed than for the baseline version, with the output deviating by 42% on average and 71% at its maximum point.The proof of concept has been made, being that approximate computing can indeed improve the throughput of TPS and make them more feasiable. It is pointed out however that only one single application type was tested, with a certain input trace. The hash table method implemented can behave differently depending on what application and/or data it is working with. It is therefore suggested that a pre-analysis of the specific dataset and application can be done at design time, in order to check feasiability of applying approximations for the certain case considered. / Internet of Things (IoT) håller på att bli en mer och mer utbredd teknik, eftersom det inte bara underlättar rutiner i vårt liv, utan det hjälper också industrin och företag att bli effektivare. Den höga potentialen med IoT kan också hjälpa till att ge stöd åt vår egen befolkning på jorden, genom precisionslantbruk, smart transport, smarta städer och mer. Det är därför viktigt att IoT görs skalbart på ett hållbart sätt för att säkra vår egen framtid.Det nuvarande arbetet handlar om transientdrivna system (TPS), vilket är inbäddade system som använder energiskörning som sin enda kraftkälla. I sin grundform har TPS ofta återställningar på grund av opålitlig tillgång till energi från miljön. Ursprungligen är därför sådana systems genomströmning lägre än deras batteriaktiverade motsvarigheter. För att förbättra detta använder TPS kontrollpunkter i RAM och processortillstånd till icke-flyktigt minne, för att hålla beräkningsförloppet sparat under strömförlustintervaller.Syftet med detta projekt är att sänka antalet kontrollpunkter som krävs under en applikationskörning på en TPS i ett generiskt fall, genom att använda ungefärlig datorberäkning. Energibehovet för TPS sänks med ungefärliga belopp, vilket innebär att fler resultat kommer när systemet arbetar mellan strömförlustperioder. För denna studie implementeras memoiseringstekniken i form av en hashtabell. Kalman-filtret tas som testapplikation för att köra på Microchip SAM-L11 inbäddad plattform.Memoization-tekniken lyckas ge en förbättring för Kalman-applikationen som beaktades, jämfört med den ursprungliga baslinjeversionen av programmet. En användare får ”balansera” mellan mer energibesparingar men mer felaktiga resultat eller motsatsen genom att justera en ”kvalitetsrat”-variabel epsilon ϵ. Till exempel, för en epsilon ϵ = 0.7, är förbättringen 32% färre kontrollpunkter som behövs än för baslinjeversionen, med en utdata avvikelse med 42% i genomsnitt och 71% vid sin högsta punkt.Beviset på konceptet har gjorts, att ungefärlig databeräkning verkligen kan förbättra genomströmning av TPS och göra dem mer genomförbara. Det påpekas dock att endast en enda applikationstyp testades, med ett visst inmatningsspår. Den implementerade hashtabellmetoden kan bete sig annorlunda beroende på vilken applikation och/eller data den arbetar med. Det föreslås därför att en föranalys av det specifika datasättet och applikationen kan göras vid designtidpunkten för att kontrollera genomförbarheten av att tillämpa ungefärliga belopp för det aktuella fallet.

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This thesis presents an active clamp forward converter for use in the Energy Harvesting From Exercise Machines project. Ideally, this converter will find use as the centerpiece in a process that links elliptical trainers to the California grid. This active clamp forward converter boasts a 14V-60V input voltage range and 150W power rating, which closely match the output voltage and power levels from the elliptical trainer. The isolated topology outputs 51V, higher than previous, non-isolated attempts, which allows the elliptical trainers to interact with a central grid-tied inverter instead of many small ones. The final converter operated at greater than 86% efficiency over most of the elliptical trainer’s input range, and produced very little noise, making it a solid choice for this implementation.

This thesis entails the design and fabrication of a smartphone charger that is powered by a bicycle dynamo hub. In addition to the design and validation of the charger prototype, this thesis involves the testing and characterization of the dynamo hub power source, the design and construction of specialized test equipment, and the design and prototyping of a handlebar-mounted case for the smartphone and charging electronics. With the intention of making the device a commercial product, price, aesthetics, and marketability are of importance to the design. An appropriate description of the charger circuit is a microcontroller-based energy management system, tailored to meet strict power demands of current smartphones. The system incorporates a switched-mode power supply, lithium polymer battery, microcontroller, and specialized protection circuitry. Prototype testing confirms that the circuit meets the charging requirements of the smartphone at bicycle speeds ranging from 7 miles per hour to as high as 55 miles per hour.

Tire pressure monitoring systems (TPMSs) predict over- and underinflated tires, and warn the driver in critical situations. Today, battery powered TPMSs suffer from limited energy. New sensor features such as friction determination or aquaplaning detection require even more energy and would significantly decrease the TPMS lifetime. Harvesting electrical energy inside the tire of a vehicle has been considered as a promising alternative to overcome the limited lifetime of a battery. However, it is a real challenge to design a system, that generates electrical energy at low velocities while being robust at 200 km/h where radial accelerations up to 20000 m/s2 occur. This work focusses on developing different electromechanical energy transducers that meet the high requirements of the automotive sector. Different approaches are addressed on how the change of acceleration and strain within the tire can be used to provide mechanical energy to the energy harvester. The energy harvester converts the mechanical energy into electrical energy. In this thesis, piezoelectric and electromagnetic transducers are discussed in depth, modelled as electromechanical networks. Since the transducers provide energy in the form of an AC voltage, but sensors require a DC voltage, various common interface circuits are compared, using LTspice and applying method of the stochastic signal analysis. Furthermore, a buck-boost converter concept for the electromagnetic energy harvester is optimized and improved. Experiments on a tire test rig validate the theoretically determined output and confirm that well designed energy harvesters in the tire can generate much more energy than required by an TPMS not only at high velocities but also at velocities as low as 20 km/h.