In this study the relationship between the dynamic response of the flexible substrate and the power generation for energy harvesting system is proposed. High electro-mechanical transformation of piezoelectric materials, high efficient energy transfer of mechanical structure and controlled circuit make the piezoelectric generator a high performance. The devices of cantilevers with lump structures on the flexible substrate and piezoelectric film (ZnO) are designed. Then some individual layers of power generator are stocked in parallel to form a multi-layer system with a broad resonant band width. When the generator is operated in a wide frequency range vibration environment, the multi-layer piezoelectric films in the form of cantilever structures can induce current. First the finite element method for the piezoelectric cantilever beam is constructed by using ANSYS software. Both modal analysis and harmonic response analysis are performed to obtain the structural modal parameters and frequency response functions, respectively. Besides, the beam structure is modeled by 3D coupled field piezoelectric element. This research will apply Taguchi¡¦s method to design including variations of dimensions and material properties for energy harvesting system. The flexible substrate is polymeric film (PET). Imprinting process is applied to transfer the simulated geometric configuration onto a flexible substrate to obtain a maximum power output. The results show the single devices can improve efficiently by using lump structures on the flexible substrate, the generator could achieve maximum OCV of 2.25V which is 0.276£gW every centimeter squared when attached to a stable source of vibration. The multi-layer system can be used in 50~500Hz of low frequency environment. Furthermore, the output voltage (OCV) is upward when the flexible substrate with low Young¡¦s modulus.

La récupération d'énergie thermique basée sur les générateurs thermoélectriques (TEG) est utilisée dans de nombreuses applications telles que les dispositifs médicaux auto-alimentés. La sûreté de fonctionnement et la continuité de service de ces systèmes sont aujourd'hui des préoccupations majeures. Ainsi, toute défaillance au niveau d'un des interrupteurs commandables de la circuiterie électronique d'interface peut provoquer de graves dysfonctionnements du système. Tout défaut non détecté et non compensé peut mettre en danger l'ensemble du système et interrompt l'alimentation en énergie de la charge. Par conséquent, la mise en œuvre d'une compensation de défaut efficace et rapide est impérative afin d'assurer la continuité de service. Dans ces travaux de recherche, nous étudions la continuité de service d'une interface électronique pour TEG basée sur une conversion à deux étages Buck/Buck-Boost cascadés. Une modélisation électrique générique (modèle de Thévenin) du TEG sous différentes conditions de fonctionnement et prenant en compte l'ensemble des résistances thermiques de contact est tout d'abord présentée. Ensuite, une méthode de compensation de défaut de type circuit-ouvert au niveau de l'interrupteur commandable de l'un des deux convertisseurs DC-DC est également proposée. Nous présentons une topologie originale de convertisseur DC-DC à tolérance de pannes, sans redondance matérielle classique. Cette topologie permet d'assurer la continuité de service du système de récupération d'énergie en mode nominal. Les études théoriques ont été validées par simulation et par des tests expérimentaux / Thermal energy harevsting based on thermoelectric generators is used in many applications such as self-powered medical devices. The reliability and continuity of service of these systems are now major concerns. Furthermore, any failure in the controllable switch of the electronic interface circuitry can cause serious system malfunctions. Any undetected and uncompensated fault can endanger the entire system and interrupt the power supply to the load. Therefore, the implementation of an efficient and rapid fault compensation is imperative in order to ensure the continuity of service. In this research, we study the continuity of service of an electronic interface for TEG, based on a two-stage conversion cascaded Buck/Buck-Boost. A generic electrical modeling of the TEG model under different operating conditions and with taking into account all the thermal contact resistances is first presented. Next, an open-circuit fault compensation method of the controllable switch of one of the two DC-DC converters is also proposed. We present an original fault-tolerant DC-DC converter topology with no conventional hardware redundancy. This topology ensures the continuity of service of the energy recovery system in nominal mode. Theoretical studies were validated by simulation and experimental tests

Mechanical vibrations in large structures such as buildings, bridges, dams and critical frequencies in large machinery generally have low frequencies (100Hz-1000Hz). To monitor large areas of such structures we need huge network of low cost, easily manufacturable, self-powered and stand-alone vibration spectrum sensors. The sensors should also consume very little power during their overall operation cycle and have moderately high frequency resoultion. The thesis provides mathematical analysis, design and development of stand-alone, low frequency vibration spectrum analyzer .A mechanically stretched polymer piezoelectric membrane, which has a fixed length and tension, can act as a single frequency detector due to its unique resonant frequency. Stretching multiple ribbons of diffferent lengths and tensions, a vibration spectrum analyzer, which gives the Fourier frequency components present in an arbitrary mechanical input vibration, can be designed. The thesis presents a detailed description of experiments to evaluate a low frequency vibration spectrum analyzer system that accepts an incoming input vibration and directly provides the spectrum as output. Polymer piezoelectric materials being easily manufacturable these sensors can be deployed in wide area sensor networks that monitor large structures. The thesis also shows design of a vibration energy harvesting system based on the concept of harvesting energy at low frequencies. The need for developing such an energy harvesting system arises from the necessity of making the vibration sensor, self-powered. Multiple experimental tests were performed before developing a prototype vibration energy harvesting circuit.

Internet of Things (IoT) är en kraftfull plattform för att koppla den fysiska världen till den digitala. IoT och modern sensorteknik möjliggör många nya applikationer inom till exempel industriell övervakning, hälsovård,miljöövervakning, smarta städer, smarta transport och smartlivsstil. I många av dessa applikationer är sensornoder utplacerade i utomhusmiljöer, där de bör fungera under långa tidsperioder. IoT-noder lider av kapacitetbergränsade batterier vilket innebär att deras funktion beror på batteriets livslängd. En lösning kan vara att implementera ett energikördsystem till IoT-noder utomhus. Solenergi är den mest lättillgängliga och användbara energikällan utomhus.Denna energi skördas med hjälp av en solcell (PV-cell). Energin som genereras av solcellspaneler varierar beroende på solstrålningsintensitet och andra faktorer. Syftet med denna undersökning har varit att utveckla en solcellsförsörjningsenhet för IoT-noder utomhus. Detta görs genom att hämta energi från omgivningen (solenergi) och använda den i samband med en Power ManagementIntegrated Circuit (PMIC) och en energilagringsenhet kan livslängden för IoT-noder förlängas samtidigt som underhållskostnader minskas.I undersökningen användes en uppskattningsmetod för att uppskatta solcellens totala energiproduktion, vilket hjälper för att konfigurera en solcellspanel som kan leverera lämplig energi till energiskördsystemet och minska energiförlusten i systemet. En lämplig energi krävs för att PMIC:n ska fungera väl samt systemet ska driva IoT-noder. Denna undersökning har visat att solenergiskördsystemet som består av en självgjord mindre panel, en BQ25570 och en energilagringsenhet (antingen en superkondensator eller ett batteri) kan översvämningsmätaren drivas under sommaren för det första fallet och under hela året för det andra fallet. Om två i parallell KXOB25-01X8F-TR används i systemet i stället för den mindre panelen kan luftkvalitetmätaren drivas under sommaren medan om tre iparallell KXOB25-01X8F-TR används i stället kan noden drivas under hela året. Energiskördsystemet ger mer än 80% effektivitet. / The Internet of Things (IoT) is a powerful platform for connecting the physical world to the digital. IoT and modern sensor technology enable many new applications in domains such as industrial monitoring, health care, environmentalmonitoring, smart cities and so on. In many of these applications, sensor nodes are deployed in outdoorenvironments, where they should operate for long periods oftime. But IoT nodes suffer from capacity-limited batteries,which means that their function depends on the battery life. One solution may be to implement an energy harvestingsystem for IoT nodes outdoors. Solar energy is the most readily available and useful source of energy outdoors. This energy is harvested using a solar cell (PV cell). The energy generated by solar cell panels varies depending on the solar radiation intensity and other factors. The purpose of this study has been to develop a solar cell supply unit for outdoor IoT nodes. This is done by extracting energy from the environment (solar energy) and using it in conjunction with a Power Management Integrating Circuit (PMIC) and energy storage device, the lifespan of IoT nodes can be extended while reducing maintenance costs. The study used an estimation method to estimate solar cell total energy production, which helps to configure a solar cellpanel that can supply suitable energy to the energyharvesting system and reduce the energy loss in the system. A suitable energy is required for the PMIC to work well and the system to power IoT nodes.This study has shown that the solar energy harvesting system consisting of a self-made smaller panel, a BQ25570 and an energy storage unit (either a supercapacitor or a battery), the flood meter can be operated during the summer for the first case and throughout the year for the second case. If two inparallel KXOB25-01X8F-TR are used in the system instead of the smaller panel, the air quality meter can be operated in the lower summer, while if three in parallel KXOB25-01X8F-TR areused instead, the node can be operated throughout the year. The energy harvesting system provides more than 80% efficiency.

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