Neste trabalho, é apresentado um estudo sobre um sistema de micro geração de energia a partir da vibração de uma viga em balanço utilizando um transdutor piezoelétrico. A análise é feita levando-se em consideração as dimensões da viga utilizada, tipo de gerador piezoelétrico e diferentes tipos de cargas acopladas a este. O sistema de geração tem sua excitação realizada por um atuador piezoelétrico, que é alimentado por uma fonte de tensão com amplitude, frequência e forma de onda ajustáveis. A avaliação da potência de saída e influência dos diferentes tipos de carga acoplados a saída são analisados. As cargas utilizadas são: puramente resistiva, resistiva-capacitiva e não linear, por meio de um retificador de onda completa. Para avaliar experimentalmente os resultados analíticos foi utilizado um protótipo de uma viga em balanço construída com uma barra de alumínio exposta a uma excitação, induzida por um outro transdutor piezoelétrico ligado a uma placa dSpace controlada por um computador. Os parâmetros do sistema são identificados sendo possível determinar sua influência na saída e realizando assim uma análise pontual do micro gerador piezoelétrico quando submetido a uma carga qualquer. Os resultados da geração com os diferentes tipos de cargas são comparados, bem como a influência destas na dinâmica do sistema. As potências máximas são apresentadas em diferentes modos de vibração depois de otimizadas. Foram obtidos os seguintes resultados: 3;357mW com uma resistência de 200k no primeiro modo; 13;17mW com uma resistência de 50k no segundo modo; para o terceiro e quarto modos de vibração a máxima potência é obtida com a resistência de 10k, sendo 10;22mW e 15;63mW, respectivamente. A alteração da frequência de vibração é de aproximadamente 0;2% para os modos de vibração em função da resistência máxima e mínima. Para a carga resistiva-capacitiva, o comportamento da geração não é afetado significativamente para os valores de resistência de 1M e 100k. Com os valores de 10k e 1k a potência ativa se eleva em 30%, aproximadamente. O comportamento da carga não linear é aproximado por uma impedância com característica capacitiva. Sendo que, com a elevação da frequência, a impedância vista pelo gerador piezoelétrico é diminuída. A energia armazenada é de 0;8039mJ, 2;5245mJ e 1;3041mJ para o primeiro, segundo e terceiro modos de vibração, respectivamente. / This work presents a study of a energy harvesting system based on vibration from a cantilever beam utilizing a piezoelectric generator. The analysis considers the dimensions of the beam, type of piezoelectric generator and di erent types of loads coupled. A piezoelectric actuator is handles for the system excitement, powered by a voltage source with adjustable amplitude, frequency and shape. Are evaluate the output power and the in uence of di erent charge types coupled to the piezoelectric generator. The loads are purely resistive, resistive-capacitive and non-linear, by a full-wave bridge recti er. To check experimentally the analytical results, are used a prototype of a cantilever beam constructed with an aluminum bar exposed to an excitation induced by another piezoelectric transducer attached to a dSpace board controlled by a computer. The system parameters are individually identi ed to determine their in uence on output, allowing the punctual analysis of the piezoelectric harvesting when subjected to any load. The results of power generation are compare with di erent types of loads as well as its in uence on the dynamic of the system. After a optimization, the greatest power delivered to the load happen in di erent vibrational modes. We obtain the following results: 3:357mW with a 200k resistance in the rst mode; 13:17mW with a 50k resistance in the second mode, for the third and fourth vibration modes greatest power is obtained with the 10k resistance, being 10:22mW and 15:63mW, respectively. The modi cation of the vibration frequency are approximately 0:2% for all vibration modes depending on the largest and smallest resistance. For the resistive-capacitive load, the generation behavior are not a ect to the 1M and 100k resistance. With the 10k and 1k values, the active power increases by approximately 30%. The nonlinear load behavior are approach by an impedance with capacitive characteristics. With increasing of frequency, the impedance seen by the piezoelectric harvester is decreased. The energy stored is 0:8039mJ, 2:5245mJ and 1:3041mJ for the rst, second and third vibration modes, respectively.

Esta Tese apresenta o desenvolvimento de um protótipo de um microgerador termoelétrico para captação de energias residuais baseado no Efeito Seebeck com sistema de transferência de calor intercambiável. Neste sentido, desenvolveu-se dois sistemas de transferência térmica, sendo um para captação do calor residual de processos industriais constituído por um módulo denominado captor de calor intercambiável e por outro módulo para resfriar o sistema. Destaca-se que o sistema térmico desenvolvido permite a sua adaptação ao processo industrial por meio da troca do captor de calor, otimizando a transferência térmica para o microgerador termoelétrico. Com base nos dados medidos fez se um tratamento dos dados obtendo-se uma tensão de circuito aberto de Vopen=0,4306xΔT [mV] e uma resistência interna de R0=9,41Ω, com uma tolerância de ΔRint=0,77Ω tal que Rint=R0±ΔRint=9,41±0,77Ω. As medições feitas com a condição de máxima potência de saída foi obtida em um gradiente de temperatura de ΔT=80°C resultando numa potência máxima Pout≈29W. Como resultado obteve-se o protótipo de um microgerador termoelétrico baseado no Efeito Seebeck para captação de energias residuais, customizado e adaptado às características do processo industrial e à respectiva carga (potência e tensão), permitindo a troca e alteração da configuração do sistema de transferência de calor bem como, a reconfiguração do arranjo dos módulos termoelétricos. / This thesis presents the development of a prototype of a thermoelectric microgenerator to energy harvesting based on the Seebeck Effect with interchangeable heat transfer system. In this sense, it developed two heat transfer systems, one for capture of waste heat from industrial processes consisting of a sensor module called interchangeably heat and cool the module to another system. It is noteworthy that the thermal system developed allows its adaptation to industrial process by exchanging the sensor heat, optimizing heat transfer to the thermocouple microgenerator. Based on measured data has a data processing yielding a open circuit voltage of Vopen=0,4306xΔT and an internal resistance of R0=9,41Ω, with a tolerance of ΔRint=0,77Ω such that Rint=R0±ΔRint=9,41±0,77Ω. The measurements made on the condition of maximum output was obtained at a temperature gradient of ΔT=80°C resulting in a maximum power Pout≈29W. As a result we obtained a prototype thermoelectric microgenerator based on Seebeck effect to energy harvesting, energy customized and adapted to the characteristics of industrial process and its load (power and voltage), allowing the exchange and change the configuration of the transfer system heat as well as reconfiguring the arrangement of thermoelectric modules.

O estudo das vibrações é importante para prevenir danos em equipamentos ou mesmo evitar catástrofes de grande natureza. Nesse sentido, aproveitar a energia que seria dissipada na vibração e contribuir no controle do sistema representa um grande avanço tecnológico. O termo Energy Harvesting (Colheita de Energia) está relacionado ao contexto do aproveitamento energético, utilizando sistema de conversão para transformação da energia em eletricidade. Através de um dispositivo com viga engastada e massa inercial na extremidade, é possível realizar o estudo de vibração e coleta de energia, ao se considerar uma estrutura piezelétrica acoplada na viga e conectada a um circuito elétrico com resistor. Estruturas inteligentes que atuam na conversão de energia mecânica em elétrica, ou vice-versa, são fundamentais para esse estudo, o que motiva a inclusão dos sensores piezelétricos no projeto de dispositivos estudados e sujeitos a vibrações. Por outro lado, otimizar parâmetros de projeto é fundamental para aumentar a amplitude de vibração e tornar o processo com maior desempenho, tendo em vista maior captação de energia. Ainda, parâmetros otimizados podem estar sujeitos a incertezas do projeto e variações, devido a flutuações ambientais, como temperatura, pressão, propriedades dos materiais, geometria, etc. Por isso, técnicas robustas que tornem os projetos menos sensíveis a variações são interessantes para serem abordadas. Embora métodos de projetos robustos sejam eficientes, poucas pesquisas têm sido feitas na área da dinâmica de vibrações e alguns processos podem demandar tempo computacional dependendo do estudo ou projeto. Este trabalho tem como propósito abordar um método específico de projeto robusto focado em uma metodologia com matrizes chamadas ortogonais. Além disso, o método determinístico via algoritmo de Programação Sequencial Quadrático (SQP) é utilizado. O trabalho consiste numa abordagem para coleta de energia em um modelo de viga engastada, otimizando parâmetros e inserindo incertezas no sistema para análise de robustez e verificação de comprimentos adequados de vigas para os dispositivos. Os resultados mostram um aumento da energia coletada, analisando funções de resposta em frequências para saída de potência, diante de uma entrada de deslocamento no engaste do dispositivo, projetado via otimização determinística, além de aumento de robustez de acordo com certos critérios considerando circuito elétrico com resistência corretamente selecionada. / The study of vibrations is important to prevent damage to equipment or even prevent major catastrophes. In this sense harvesting the energy that would otherwise be dissipated in vibration and contributing to the control of the system represents a great technological advance. The term Energy Harvesting is related to the context of energy use, using a conversion system to transform energy into electricity. Through a device with clamped beam and inertial mass at the end, it is possible to study the vibration and energy harvesting, considering a piezoelectric structure coupled to the beam and connected to a resistance electric circuit. Smart structures that act in the conversion of mechanical energy to electrical energy, or vice versa, are fundamental for this study, which motivates the inclusion of piezoelectric sensors in the design of studied devices and subject to vibrations. On the other hand, optimizing design parameters is fundamental to increase the amplitude of vibration and increase process performance, in view of greater power uptake. Furthermore, optimized parameters may be subject to design uncertainties and variations due to environmental fluctuations such as temperature, pressure, material properties, geometry, etc. Therefore, robust techniques that make designs less sensitive to variations are interesting to be addressed. Although robust design methods are efficient, few researches have been done in the area of vibration dynamics and some processes may require computational time depending on the study or project. This work aims to address a specific method of robust design focused on a methodology with matrices called orthogonal. In addition, the deterministic method using Sequential Quadratic Programming (SQP) algorithm is used. The work consists of an approach to harvest energy in a clamped beam model, optimizing parameters and inserting uncertainties in the system for robustness analysis and verification of adequate beam lengths for the devices. The results show an increase in the harvested energy, analyzing frequency response functions for power output, in the face of a displacement input in the device clamp, designed through deterministic optimization,besides increasing robustness according to certain criteria considering electric circuit with correctly selected resistance.

Depuis des siècles nous utilisons des véhicules équipés des systèmes de suspension de vibrations. Ils permettent d'avoir un confort acceptable et ajoutent de la sécurité à la conduite. Les nouveaux systèmes installés dans les véhicules sont des systèmes actifs. Ils peuvent être adaptés selon les exigences en temps réel. Ces types de systèmes sont utilisés pour l'amortissement de vibrations et pour l’isolation vibro-acoustique. Dans la thèse nous présentons une nouvelle approche d'un système adaptatif pour les applications automobiles. Nous faisons l'hypothèse qu’un portage d'un système centralisé en système distribué peut améliorer son efficacité. Nous proposons un réseau de capteurs sans fil pour l’amortissement de vibrations dans les applications automobiles. Un capteur du réseau est capable de mesurer des vibrations, d’amortir des vibrations et de récupérer l’énergie depuis les vibrations en utilisant un seul élément piézoélectrique (la méthode Serial-SSHI). Ensuite nous validons le réseau de capteurs sur une structure mécanique de type plaque. Les mesures sont comparées avec des simulations d’éléments finis. Les résultats des mesures et des simulations confirment le choix des solutions. Le nœud du réseau fournit ses fonctionnalités destinées avec une efficacité acceptable. Nous validons la récupération d’énergie depuis les vibrations et la mesure des vibrations. Ensuite nous validons un effet local d’amortissement de vibrations et un effet global (le réseau de capteurs permet d’avoir une action d’amortissement complémentaire). / For centuries we have used vehicles equipped with the vibration suspension systems. These systems are used to provide comfort and safety. Nowadays we are implementing the active systems which can be adapted according to the real-time requirements. These types of systems are used to damp vibrations and to provide noise and vibration insulation. In the thesis we present a new approach of an adaptive system for automotive applications. We assume that a porting of a centralized system in a distributed system can improve its effectiveness. We offer a wireless sensor network for damping vibration in automotive applications. A network sensor is able to measure the vibrations, damp the vibrations and energy harvesting from vibrations by using a single piezoelectric element (Serial-SSHI method). We validate the network of nodes on a mechanical structure. The measurements are compared with finite element simulations. The results of measurements and simulations confirm the choice of solutions. The network node provides designed functionality with acceptable efficiency. We also validate the energy harvesting and the vibration measurements. The outcome of the work confirm a local effect of vibrations damping and a global effect (the designed Wireless Sensor Network provides a supplementary damping action).

This thesis first presents a new cooperative wireless communication network strategy that incorporates energy cooperation and data cooperation. The model establishment, design goal formulations, and algorithms for throughput maximization of the proposed protocol are presented and illustrated using a three-node network with two energy harvesting (EH) user nodes and a destination node. Transmission models are established from the performance analysis for a total of four scenarios. Based on the models, we seek to find optimal energy management strategies by jointly optimizing time allocation for each user, power allocations over these time intervals, and data throughputs at user nodes so as to maximize the sum-throughput or, alternatively, the minimum throughput of the two users in all scenarios. An accelerated Newton barrier algorithm and an alternative algorithm based on local quadratic approximation of the transmission models are developed to solve the aforementioned optimization problems. Then the thesis extends the cooperative strategy to multi-source wireless communication network, where N source users communicate with the destination via one relay that harvests energy from the RF signals transmitted by the sources through time-division multiple access (TDMA). We characterize the Energy-Throughput (E-T) tradeoff regions between the maximum achievable average throughput of the sources and the total amount of saved energy in three circumstances. For the case N=1, all harvested energy will be used to forward the message. For the case N>1, we compare two transmission strategies: one is common PS ratio strategy that the relay adopts the same PS ratio for all sources; the other is individual PS ratio strategy that each source uses an individual PS ratio. Numerical experiments under practical settings provide supportive evidences to our performance analysis. / Graduate

Dans le domaine de l'Internet des Objets (IOT) les matériaux magnétoélectriques composites (MEC) trouvent leurs potentiels utilités dans la récupération d'énergie de microsystèmes autonomes. L'aspect géométrique des matériaux MEC se traduit par l'assemblage de matériaux piézoélectriques et magnétostrictifs sous formes laminaires ou sous formes de mixture par grains. Dans tous les cas ces matériaux possèdent, sous certaines conditions, des coefficients magnétoélectriques qui peuvent fournir des tensions et des puissantes suffisantes pour alimenter des microsystèmes autonomes. Mes travaux de recherche ont porté essentiellement sur une contribution à la modélisation de ces matériaux MEC à l'aide de méthodes analytiques et d'un code numérique basé sur la méthode des éléments finis (MEF) en 2D. Une méthode basée sur la combinaison du tenseur de Maxwell avec le model de Jiles-Atherton modifié a été proposée pour inclure dans la MEF la non-linéarité des couches magnétostrictives. Une étude sur les performances des structures multicouches a été réalisée afin de déterminer la configuration optimale pour les matériaux élaborés à base de couches minces. Une potentielle application dans le domaine biomédical est finalement présentée afin de prouver l'efficience d'un transducteur d'énergie MEC dans ce domaine. Une série de mesures sur un composite bilame est présentée à la fin afin de montrer le plein accord avec la partie modélisation réalisée. / Currently, the "Internet of Everything" (IoE) technologies have attracted significant researchers in the international scientific community. The IoE is based on the idea that identifiable objects are located and controlled via the Internet. To achieve this goal, it is necessary to design embedded systems in millimeter/micrometer scales composed of wireless sensor nodes while overcoming a major drawback of the excessive use of batteries which are limited in lifetime and yield pollutants. The problem calls for the supply of green energy harvesting for wireless sensors. To utilize mechanical vibrations and electromagnetic energy more efficiently, it would be necessary to get simultaneously both energies using materials sensitive to the electromagnetic field and the mechanical vibration such as magnetoelectric materials (ME) that combine the magnetostrictive and piezoelectric effects. Experimental results of ME coefficients from the fabricated ME composites have confirmed the possibility to obtain a few of V/(cm∙Oe) in no-resonant regime and few tens of V/(cm∙Oe) in resonant regime. In case of classical laminate bulk material (Terfenol-D/PZT/Terfenol-D), the delivered powers into optimal impedance are in the order of mW/ cm3. Thus in this context the research work in this thesis focuses on the establishment and assessment of the modelling approaches. The contribution includes analytical numerical methods and a 2D multiphysics finite element method to estimate the performance of the ME materials according to different polarizations and parameters.

Energy harvesting system is a system which could convert ambient energy into electrical power, its output depends on the energy availability of ambient conditions. For indoor condition, light is a typical available energy, and solar panel could be used to harvest it. To determine the light energy availability of an unknown condition, normally, a lot of measurements is needed, and it will cost a long time. This paper introduced a whole design process of a simulation system, it used modelling method to estimate the energy availability of unknown light condition, and this method is more quickly. A matched measurement system for solar panel and environmental parameters was built firstly. Then, all these environmental parameters were analyzed to find out their influence on solar panel. These parameters, which have relation to the output of the solar panel were thought as influence factors and used for model and classifier building. To get an accurate simulation result, different modeling and classification methods were compared and some suggested methods were picked out. Comparing the simulation result with the real output measurement, the method with minimum error was accepted in the final system. A user interface was built in the end to make this system become more user-friendly. This system could be used to simulate the energy availability of a new condition and analyze the error of simulation results which generated by different methods.

Since the wireless sensor network has appeared, it plays an important role in human life. It has the ability to help people automatically sense the real world, where is inaccessible before. Although the applications of wireless sensor networks are increasing nowadays, one of the great issues facing sensor network is the lifetime of a system. Since the system relies on the limited battery, finite lifetime is its biggest challenge. Fortunately, solar energy harvesting for the outdoor environment is promised to address that problem. Compared with that, indoor energy harvesting is still an immature field for most applications, since it is complex to estimate the available energy for indoor lights. To complement the vacancy of indoor energy harvesting field, improve the performance of the traditional estimation model, a new solar cell model is proposed to substitute the traditional solar cell model. The traditional estimation model is used to roughly dimension the indoor system, regardless of the different impact generated by different light sources. The new estimation model, was established under the real indoor environmental conditions. A classification model is created to distinguish the sort of the light sources. The single solar cell of the traditional model is replaced by 5 different solar cell models fitted for each kind of light source. With that, the system has the ability to select the most suitable solar cell model based on the classification result. Moreover, a verification model was built to evaluate both estimation models. The evaluation result shows that the new model has the ability to perform well under changing light condition.

Thermoelectric generators (TEG) directly convert heat energy into electrical energy. The impediments as to why this technology has not yet found extensive application are the low conversion efficiency and high costs per watt. On the one hand, the manufacturing process is a cost factor. On the other, the high-­‐priced thermoelectric (TE) materials have an enormous impact on the costs per watt. In this thesis both factors will be examined: the production process and the selection of TE materials. Technical screen printing is a possible way of production, because this method is very versatile with respect to the usable materials, substrates as well as printing inks. The organic conductor PEDOT:PSS offers reasonable thermoelectric properties and can be processed very well in screen printing. It was demonstrated by prototypes of fully printed TEGs that so-­‐called vertical printed TEGs are feasible using standard graphic arts industry processes. In addition, the problems that occur with print production of TEGs are identified. Finally, approaches to solve these problems are discussed.

Les progrès technologiques accomplis durant ces dernières décennies dans les domaines des microsystèmes et des radiocommunications nous permettent de réaliser des composants communicants miniaturisés à faible coût afin de constituer des réseaux de capteurs sans fil. Typiquement, chacun de ces composants intègre une ou plusieurs unités de mesures (capteur), une unité de traitement de données, une unité de communication radio et une batterie. De ce fait, un nouveau domaine de recherche s’est créé pour étudier le déploiement de ces réseaux afin d’offrir des solutions de surveillance et de contrôle à distance, notamment dans des environnements complexes ou inaccessibles. Les domaines d’application de ces capteurs sont très variés, allant de la domotique au militaire en passant par le médical et les infrastructures civiles. Souvent, ces applications impliquent des contraintes sévères en terme d’autonomie qui idéalement devrait atteindre plusieurs dizaines d’années. Pour atteindre cet objectif, il est à la fois nécessaire de réduire la consommation énergétique du nœud capteur et de trouver d’autres solutions d’alimentation en énergie pour le nœud. Pour adresser ce deuxième point, la récupération d’énergie à partir de l’environnement (solaire, vibratoire, thermique, etc.) semble représenter une solution idéale pour alimenter un nœud capteur, bien que celui-ci doive s’adapter aux faibles quantités d’énergie récupérées par ces systèmes, ainsi qu’à leurs variations et intermittences. Ces travaux de thèse s’intéressent donc à la problématique de la simulation et de la réduction de la consommation des nœuds de capteurs sans-fil et autonomes en énergie. Dans un premier temps, nous avons développé la plateforme HarvWSNet, un environnement de co-simulation alliant le simulateur de réseaux WSNet et Matlab permettant ainsi la modélisation précise et la simulation hétérogène des protocoles de communication (typiquement à événements discrets) et des systèmes de récupération d’énergie (qui possèdent typiquement un comportement à temps continu). Nous avons démontré que cette plateforme permet de réaliser très rapidement des études de pré-prototypage de scénarios applicatifs de déploiement et ainsi réduire le temps de conception de ces nouvelles technologies. Grâce à la modélisation précise des éléments du système de récupération d’énergie (batterie, supercapacité, etc.) permise par cette plateforme, nous avons étudié et évalué la durée de vie de déploiements à large échelle de réseaux de capteurs alimentés par des systèmes de récupération d’énergie (solaire et éolien). La deuxième contribution de cette thèse concerne l’étude et l’implémentation de stratégies de reconfiguration dans l’interface de communication radio, qui est souvent la principale source de consommation d’énergie d’un capteur, afin de permettre au nœud et/ou au réseau de minimiser sa consommation lorsque le bilan de liaison RF est favorable. A cette fin, nous avons proposé une approche originale grâce au développement d’un simulateur de réseau dédié, EnvAdapt (basé sur WSNet). Dans cette nouvelle plateforme, des modèles de consommation des différents blocs du transceiver radio et des algorithmes de reconfiguration ont été implémentés afin d’étudier l’impact de la reconfiguration des performances de la radio sur la qualité de service et l’autonomie d’un réseau de capteurs. / Technological advances achieved over the past decade in the fields of microsystems and wireless communications have enabled the development of small size and low cost sensor nodes equipped with wireless communication capabilities able to establish a wireless sensor network (WSN). Each sensor node is typically equipped with one or several sensing unit, a data processing unit, a wireless communication interface and a battery. The challenges raised by WSNs has lead to the emergence of a new research domain which focuses on the study and deployment of such a networks in order to offer the required remote monitoring and control solutions for complex and unreachable environment. WSNs have found application in a wide range of different domains, including home and structural health monitoring, military surveillance, and biomedical health monitoring. These applications usually impose stringent constraints on the WSN lifetime which is expected to last several years. To reach this objective, it is necessary to reduce the overall energy consumption of the sensor node and to find an additional source of energy as well. To address the last point, energy harvesting from the environment seems to be a an efficient approach to sustain WSNs operations. However, energy harvesting devices, which must also be small, are usually unable to ensure a continuous operation of sensor nodes. Thus, it is necessary to adapt the WSN consumption and activity to the low and unpredictable energy scavenged. The work presented in this thesis focuses on the issue of simulation and power consumption of autonomous sensor nodes. We have first developed, HarvWSNet, a co-simulation framework combining WSNet and Matlab that provides adequate tools to accurately simulate heterogenous protocols (based on discrete-time events) and energy harvesting systems (based on continuous-time events). We have demonstrated that HarvWSNet allows a rapid evaluation of energy-harvesting WSNs deployment scenarios that may accelerate the time-to-market for these systems. Thanks to the accurate energy models (battery, supercapacitor, etc.) implemented in this platform, we have studied and evaluated a large scale deployment of solar and wind energy-harvesting WSNs. Our second contribution focuses on the implementation of energy-aware reconfiguration strategies in the radio transceiver which is usually considered as the most energy hungry component in a sensor node. These strategies are intended to reduce the excessive power consumption of the radio transceiver when the channel conditions are favorable. To this end, we have a new simulation framework called EnvAdapt (based also on WSNet) dedicated to the evaluation of reconfigurable radio transceivers for WSNs. In EnvAdapt, we have implemented the required radio transceiver behavioral and power consumption models that allows the evaluation of the impact of radio transceiver reconfiguration on the communication performance and lifetime of WSNs.