Neste trabalho, é apresentado um estudo sobre sistemas de transmissão de energia com o uso de bobinas fracamente acopladas magneticamente. A análise é feita levando-se em conta os efeitos parasitas dos componentes em um circuito equivalente considerando-se somente uma única frequência e o circuito já no regime estacionário. Esse circuito é alimentado por uma fonte de tensão senoidal e conectado a uma carga puramente resistiva por simplificação. São analisadas a potência de saída e a eficiência do circuito. Portanto um exercício de otimização dessas duas variáveis é desenvolvido ao longo desse trabalho com diferentes possíveis configurações. Um novo método de compensação do circuito utilizando quatro capacitores é apresentado. Além disso, é explorada a possibilidade de se melhorar ainda mais o resultado da compensação através do ajuste da frequência de ressonância. Inicialmente, o circuito básico sem compensação é analisado. A seguir, são desenvolvidas equações para as máximas eficiência e potência na saída para os circuitos contendo somente um capacitor de compensação. Também são demonstradas as configurações normalmente utilizadas para compensação com dois capacitores. Então a compensação de um circuito com quatro capacitores sem perdas é analisada. Finalmente, após serem adicionadas todas as perdas resistivas dos componentes do circuito, um método de busca é empregado para encontrar os valores ótimos (ou subótimos) dos capacitores que fazem o circuito alcançar a máxima eficiência ou potência na saída. Um algoritmo baseado no método Monte Carlo é apresentado de modo a obter boas soluções para o problema de otimização proposto e assim evitar a análise direta do intrincado sistema de equações resultantes da compensação com mais do que dois capacitores. Para verificar experimentalmente os resultados teóricos e das simulações foi construído um protótipo que possibilita uma variação linear e de maneira controlada do coeficiente de acoplamento entre as bobinas. Os resultados são comparados e, ainda, melhorados através do método da sintonia da frequência. / In this work, we present a study of power transmission systems using magnetically loosely coupled coils. The analysis is done taking into account the effects of parasitic components in an equivalent circuit considering only a single frequency and the circuit already in the steady state. This circuit is powered by a sinusoidal voltage source and connected to a purely resistive load for simplification. Improvements in the output power and efficiency of the circuit are the main topic. So an exercise in optimization of these two variables is developed throughout this work with different possible configurations. A new compensation method using four capacitors of the circuit is presented. Moreover, the possibility is exploited to further improve the result of compensation by adjusting the resonance frequency. Initially, the basic circuit without compensation is analyzed. The following equations are designed for maximum efficiency and output power for the circuits containing only one compensation capacitor. Also, the settings normally used to offset two capacitors are presented. So the compensation of a circuit with four capacitors lossless is analyzed. Finally, are added all the resistive losses of the circuit components, an search method is employed to find the optimal values (or suboptimal) capacitors that make the circuit to achieve maximum efficiency or power output. An algorithm based on Monte Carlo method is presented to solve the proposed optimization problem and thus avoid direct analysis of the intricate system of equations resulting from the clearing of more than two capacitors. To experimentally verify the theoretical results of simulations a prototype was constructed which allows for linear variation and a controlled coefficient of coupling between the coils. The results are compared and, moreover, improved by the method of tuning the frequency.

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

La transmission inductive de puissance (IPT) pour les véhicules électriques est une technologie émergente prometteuse qui semble capable d'améliorer l'acceptation de la mobilité électrique. Au cours des deux dernières décennies, de nombreux chercheurs ont démontré la faisabilité et la possibilité de l'utiliser pour remplacer les systèmes conducteurs classiques pour la charge de la batterie à bord du véhicule. Actuellement de nombreux efforts visent à étendre la technologie IPT vers son utilisation pour la charge pendant le mouvement du véhicule. Cette application, généralement appelée IPT dynamique, vise à surmonter la limite représentée par les arrêts prolongés nécessaires pour la recharge introduisant également la possibilité de réduction de la capacité de la batterie installée à bord du véhicule. Un système IPT est essentiellement basé sur la résonance de deux inducteurs magnétiquement couplés, l'émetteur, placé sur ou sous le sol, et le récepteur, placé sous le plancher du véhicule. La gamme de fréquence de fonctionnement typique pour les applications automobiles va de 20 kHz à environ 100 kHz. Le couplage entre les deux inductances s'effectue à travers un entrefer important, généralement d'environ 10-30 cm. Cette thèse présente les résultats des activités de recherche visant à la création d'un prototype pour l'IPT dynamique orienté vers le transport privé. A partir d'une analyse de l'état de l'art et des projets de recherche en cours dans ce domaine, ce travail présente le développement d'un modèle de circuit capable de décrire les phénomènes électromagnétiques à la base du transfert de puissance et l'interface avec l'électronique de puissance. Les analyses effectuées à travers le modèle développé fournissent la base pour la conception et la mise en œuvre d'un convertisseur dédié à faible coût et efficacité élevée pour l'alimentation du côté transmetteur. Une architecture générale de l'électronique de puissance qui gère le côté récepteur est proposée avec les circuits de protection supplémentaires. Une méthodologie pour la conception intégrée de la structure magnétique est illustrée. Cette méthodologie couvre les aspects de l'interface avec l'électronique de puissance, l'intégration sur un véhicule existant et l'installation sur l'infrastructure routière. Une série d'activités visant à la réalisation d'un site d'essai dédié sont présentées et discutées. En particulier, les activités liées à la création de l'infrastructure électrique ainsi que les questions et les méthodes d'implantation des émetteurs dans le revêtement routier sont présentées. L'objectif final est la création d'une ligne de recharge IPT dédiée de 100 mètres de long. Enfin, une méthodologie d'évaluation de l'exposition humaine est présentée et appliquée à la solution développée. / Inductive power transmission (IPT) for electric vehicles (EVs) is a promising emergent technology that seems able to improve the electric mobility acceptance. In the last two decades many researchers have proved its feasibility and the possibility to use it to replace the common conductive systems for the charge of the on-board battery. Many efforts are currently aimed to extend the IPT technology towards its use for the charge during the vehicle motion. This application, commonly indicated as dynamic IPT, is aimed to overcome the limit represented by the long stops needed for the recharge introducing also the possibility of reducing the battery capacity installed on vehicle. An IPT system is essentially based on the resonance of two magnetically coupled inductors, the transmitter, placed on or under the ground, and the receiver, placed under the vehicle floor. The typical operating frequency range for the EVs application goes from 20 kHz to approximately 100 kHz. The coupling between the two inductors takes place through a large air-gap, usually about 10-30 cm. This thesis presents the results of the research activities aimed to the creation of a prototype for the dynamic IPT oriented to the private transport. Starting from an analysis of the state of the art and the current research projects on this domain, this work presents the development of a circuit model able to describe the electro- magnetic phenomena at the base of the power transfer and the interface with the power electronics. This model provides the information at the base of the design and the implementation of a dedicated low cost-high efficiency H-bridge converter for the supply of the transmitter side. A general architecture of the power electronics that manages the receiver side is proposed together with the additional protection circuits. A methodology for the integrated design of the magnetic structure is illustrated covering the aspects of the matching with the power electronics, the integration on an existing vehicle and the installation on the road infrastructure. A series of activities aimed to the implementation of a dedicated test site are presented and discussed. In particular, the activities related to the creation of the electrical infrastructure and the issues and methods for the embedding of the transmitters in the road pavement are presented. The final goal is the creation of a dedicated IPT charging line one hundred meters long. Finally, a methodology for the assessment of the human exposure is presented and applied to the developed solution.

The U.S. transportation sector represented about 28% of all energy consumption in 2018. Petroleum products accounted for 92% of this total energy. Light-duty vehicles are the largest energy consumers in the transportation sector. The high amount of petroleum used by light-duty vehicles creates significant economic and environmental challenges. Electric Vehicles (EVs) have a higher fuel economy and can be emission-free; they are therefore an alternative solution for minimizing the negative environmental impact of internal combustion engine vehicles. However, the adoption of EVs has been limited by their limited driving range, long recharging time, and comparatively higher price. Dynamic wireless charging technology allows for charging the EV battery in motion. Charging pads are embedded in the road and the EV battery is charged while the vehicle is passing over them. This technology not only extends the EV range but also results in a considerable reduction in battery size and capacity. Therefore, dynamic wireless charging solves one of the major issues of EVs, leading to their large-scale adoption. In the first part of this dissertation, a pad optimization methodology is presented to minimize system cost and losses. Using this method, two pads are optimized, built and tested for charging the EV. In the next section, two methods are presented to estimate how much the EV is laterally misaligned with respect to the center of the charging pads. This helps to increase system efficiency and power transfer capability. Finally, new concrete-based material is presented and studied to reduce the charging pad cost and increase their durability.

Wireless is everywhere. Smartphones, tablets, laptops, implantable medical devices, and many other wireless devices are massively taking part of our everyday activities. On average, an actively digital consumer has three devices. However, most of these wireless devices are small equipped with batteries that are often limited and need to be replaced or recharged. This fact limits the operating lifetime of wireless devices and presents a major challenge in wireless communication. To improve the perpetual energy operation of wireless communication systems, energy harvesting (EH) from the radio frequency (RF) signals is one promising solution to make the wireless communication systems self-sustaining. Since RF signals are known to transmit information, it is interesting to study when RF signals are simultaneously used to transmit information and scavenge energy, namely simultaneous wireless information and power transfer (SWIPT). In this thesis, we specifically aim to study the SWIPT in multiple-input multiple-output (MIMO) relay communication systems and in cognitive radio (CR) networks. First, we study the SWIPT in MIMO relay systems where the relay harvests the energy from the source and uses partially/fully the harvested energy to forward the signal to the destination. For both the amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols, we consider the ideal scheme where both the energy and information transfer to the relay happen simultaneously, and the practical power splitting and time switching schemes. For each scheme, we aim to maximize the achievable end-to-end rate with a certain energy constraint at the relay. Furthermore, we consider the sum rate maximization problem for the multiuser MIMO DF relay broadcasting channels with multiple EH-enabled relays, and an enhanced low complex solution is proposed based on the block diagonalization method. Finally, we study the energy and data performance of the SWIPT in CR network where either the primary receiver (PR) or the secondary receiver (SR) is using the antenna switching (AS) technique. When the PR is an EH-enabled node, we illustrate the incentive of spectrum sharing in CR networks. When the SR is an EH-enabled node, we propose two thresholding-based selection schemes: the prioritizing data selection scheme and the prioritizing energy selection scheme.

The continuous growth in road transportation demand requires the development towards sustainable strategies. The concept of Smart Roads is arising as a convergence of technologies that will lead the mobility by road into a more efficient and interactive system between infrastructure, environment and vehicles. Within this context, e-mobility appears as one of the key components. The implementation of e-mobility based on Electric Vehicles (EVs) has been restricted by numerous shortcomings such as their driving range, the battery size, the dependence on charging stations and the time required for its charging. However, the electrification of the road infrastructure, which will enable a dynamic charging of the EVs while driving, is becoming a potential solution to overcome these deficiencies. This study aims to contribute for the future introduction of electrified roads (eRoads) into the current network, by focusing on the effects and consequences of embedding Inductive Power Transfer (IPT) systems in the road infrastructure. A structural design of an eRoad is conducted through a Finite Elements Analysis (FEA) by analysing the behaviour of a pavement structure based on Swedish conditions subjected to traffic loading. Valuable conclusions can be displayed from this analysis and thus, a summary concerning considerations and effects over the design, construction and maintenance of eRoads can be built. Nevertheless, this analysis must be complemented and coordinated from a lifetime perspective to reach the social, environmental and economic requirements related to the development of road infrastructure nowadays. Hence, a guideline from a life cycle approach is stated over the integration of eRoads in order to enable the assessment of the infrastructure during its different phases. To be sustainable, the development of road infrastructure must reach not just structural and appropriate performance requirements, but also preserve the environmental and economic impact. This thesis pretends to combine all these aspects as a state of the art, providing a basis that stands out the most relevant issues related to the feasible implementation of eRoads in the mid-long term.

Wireless communications has gone through tremendous growth in the past decades. There has been a shift in wireless network research from spectral efficiency and quality of service (QoS) constraints to energy efficiency and green communications to reduce power consumption. Green energy resources such as solar, wind, thermal and mechan- ical vibrations can be employed to increase the energy efficiency of energy-constrained networks such as wireless sensor networks. Converting the available energy in the sur- rounding area into electricity, energy harvesting (EH), has been the subject of recent research. EH from radio frequency (RF) signals can be utilized to prolong the lifetime of devices in energy-constrained systems. Wireless power transmission (WPT) for EH is a promising solution to provide a reliable source of energy for devices which are di cult to service due to mobility and/or hard to reach locations. The integration of relaying into conventional wireless networks is promising to increase the coverage area and reduce power consumption. However, the extra power consumed to relay signals may be a problem that can be mitigated by WPT. WPT has made it possible for relays to power themselves by capturing ambient energy wirelessly. The received signal at the relay can be utilized to both forward information and harvest energy. This dissertation focuses on practical energy harvesting schemes in wireless com- munication networks. Further, the broadcast nature of wireless systems makes wire- less transmissions more vulnerable to eavesdropping compared to wired signals. The goal of this work is to develop EH schemes that are capable of supplying sustainable energy to the relays and overcoming the secrecy hazards from potential eavesdroppers. Power splitting (PS) and time switching (TS) are studied in communication networks to prolong the lifetime of an energy-constrained relay. First, a dual hop system with an amplify and forward (AF) relay employing wireless information and power transfer (WIPT) via power splitting is studied. Optimal transmit antenna selection that max- imizes the end-to-end signal to noise ratio (SNR) at the destination is considered and the outage probability is derived. It is shown that the outage probability increases with the number of transmit antennas but this also increases the system complexity. Since the spectral efficiency with two-way relaying is higher than with one-way relaying, a two-way EH-based relay network with an eavesdropper is investigated. The secrecy capacity at the users is derived for two diversity combining cases at the eavesdropper, selection combining (SC) and maximal ratio combining (MRC). A friendly jammer is introduced to increase the secrecy capacity of the users by reducing the received signal to noise ratio at the eavesdropper since the signal of the jammer is considered as noise at the eavesdropper. The corresponding optimization problem is reformulated using the single condensation method (SCM) and geometric programming (GP) into a convex optimization problem. Then, GP is used to jointly optimize the power splitting factor of the relay and transmit powers of the two users and jammer to maximize the secrecy capacity of the system. Imperfect cancellation of the jamming signal at the relay is assumed. It is shown that increasing the power allocated to the jammer decreases the secrecy capacity at the users. However, when perfect jamming signal cancellation is assumed, increasing the power allocated to the jammer increases the secrecy capacity at the users. The secrecy capacity is also shown to be greater with a jammer than without a jammer. Channel state information uncertainty at the eavesdropper is also considered as an extra noise source. TS at the relay of a two-way EH-based relay network was also considered. GP is used to jointly optimize the time switching ratio of the relay and transmit powers of the two users and jammer to maximize the secrecy capacity of the system. It is shown that PS two-way relaying achieves a better secrecy capacity than TS two-way relaying. / Graduate

With the emergence of the Internet of things (IoT) networks, the replacement of batteries for IoT devices became challenging. In particular, the battery replacement is more expensive and cumbersome for scenarios where there are many IoT devices; or where the IoT devices are in unreachable locations; or when they have to be replaced often. Some IoT devices might be lost or forgotten, and there is a risk of hazardous chemicals leakage and e-waste in large scale in nature. Radio frequency (RF) wireless power transfer (WPT) is an alternative technology for powering those devices. It has been shown that only less than one millionth of the transmitted energy is absorbed by the receivers, the rest is absorbed by the objects in the environment. We can utilize the existing infrastructure for wireless communications such as base stations (BS) to charge IoT devices. The present work is devoted to analyze the feasibility and limitations of the battery-less operation of IoT devices with RF WPT technology and energy harvesting from existing infrastructure for wireless communications. We study the indoor and outdoor scenarios for powering of IoT devices. In the first scenario, we consider an outdoor environment where an IoT device periodically harvests energy from an existing BS and transmits a data packet related to the sensor measurement under shadow fading channel conditions. We analyze the limits (e.g., coverage range) of energy harvesting from a BS for powering IoT devices. We characterize the "epsilon-coverage range, where" is the probability of the coverage. Our analysis shows a tradeoff between the coverage range and the rate of sensor measurements, where the maximal "epsilon-coverage range is achieved as the sensor measurement rate approaches zero. We demonstrate that the summation of the sleep power consumption and the harvesting sensitivity power of an IoT device limits the maximal "epsilon-coverage range. Beyond that range, the IoT device cannot harvest enough energy to operate. The desired rate of the sensor measurements also significantly impacts the "epsilon-coverage range. We also compare the operational domain in terms of the range and measurement rate for the WPT and battery-powered technologies. In the second scenario, we consider the remote powering of IoT devices inside an aircraft. Sensors currently deployed on board have wired connectivity, which increases weight and maintenance costs for aircraft. Removing cables for wireless communications of sensors on board alleviates the cost, however, the powering of sensors becomes a challenge inside aircraft. We assume that the IoT devices have fixed and known locations inside an aircraft. The design problem is to minimize the number of WPT transmitters given constraints based on the cabin geometry and duty cycle of the IoT devices. We formulate a robust optimization problem to address the WPT system design under channel uncertainties. We also derive an equivalent integer linear programming and solve that for an optimal deployment to satisfy the duty cycle requirements of the cabin sensors. / <p>QC 20220223</p><p></p>

The purpose of this paper is to achieve wireless power transfer inside a resonating cavity, and thereby apply this to charge batteries. The idea is to convert radio frequency waves into direct current, which can charge the batteries. This was done by creating an LC-antenna, which in turn was connected to a rectifier. A data logger was also built, this to be able to read and log the power within the cavity to examine its power distribution. Because of COVID-19 restrictions, access to laboratory and equipment was limited. Due to this, smaller experiments where performed to make sure that all parts worked as intended before trying to perform tests inside the cavity resonator. The results were varied, some favorable, some not. However, all experiments gave insight and further understanding on the issue. The cavity operations had varied results. The data logger was able to pick up, at most, 7.6 % of the power output by the function generator. However, some problems arose with the rectifier which resulted in it not working for higher frequencies. Though, it was capable of rectifying RF signals at lower frequencies from a function generator, which was used to charge a battery. Consequently, there was no charging of batteries inside the cavity. However, three dimensional wireless power transfer was achieved. With some improvements to the current designs, the main goal could be accomplished

The next technological revolution, Industry 4.0, is envisioned as a digitally connected ecosystem where machines and gadgets are driven by artificial intelligence. By 2025, more than 75 billion devices are projected to serve this revolution. Many of which are to be integrated into the fabrics of everyday life in the form of smart wireless sensors. Still, two major challenges should be addressed to realize truly wireless and wearable sensors. First, the sensors should be flexible and stretchable, allowing for comfortable wearing. Second, the electronics should scavenge the energy it requires entirely from the environment, thus, eliminating the need for batteries, which are bulky, create ecological problems, etc. By addressing these two challenges, this dissertation paves the way for truly wearable sensors. The first part of the dissertation introduces a biocompatible magnetic skin with exceptional physical properties. It is highly-flexible, breathable, durable, and realizable in any desired shape and color. Attached to the skin of a user, the magnetic skin itself does not require any wiring, allowing to place the electronics and delicate components of the wireless sensor in a convenient nearby location to track the magnetic field produced by the magnetic skin. To demonstrate the performance of the magnetic skin, wearable systems are implemented as an assistive technology for severe quadriplegics, a touchless control solution for eliminating cross contaminations, and for monitoring blinking and eye movement for sleep laboratories. The second part of the dissertation is about wirelessly powering wireless sensors. In doing so, radio frequency (RF) rectifiers are a bottleneck, especially for ambient RF energy harvesting. Therefore, two RF rectifiers are introduced in standard CMOS technologies. The first architecture utilizes double-sided diodes to reduce the reverse leakage current, thus achieving a high dynamic range of 6.7 dB, -19.2 dBm sensitivity, and 86% efficiency. The second rectifier implements a dual-mode technique to lower the effective threshold voltage by 37%. Consequently, it achieves a 38% efficiency at −35 dBm input power and a 10.1 dB dynamic range while maintaining the same efficiency and sensitivity. Ultimately, combining these wireless powering techniques with the magnetic skin allows for truly wireless and wearable solutions.