Sistemas eficientes de transmissão de energia sem-fios e identificação por radiofrequência

Doutoramento em Engenharia EletrotécnicaIn the IoT context, where billions of connected objects are expected to be ubiquitously deployed worldwide, the frequent battery maintenance of ubiquitous wireless nodes is undesirable or even impossible. In these scenarios, passive-backscatter radios will certainly play a crucial role due to their low cost, low complexity and battery-free operation. However, as passive-backscatter devices are chiefly limited by the WPT link, its efficiency optimization has been a major research concern over the years, gaining even more emphasis in the IoT context. Wireless power transfer has traditionally been carried out using CW signals, and the efficiency improvement has commonly been achieved through circuit design optimization. This thesis explores a fundamentally different approach, in which the optimization is focused on the powering waveforms, rather than the circuits. It is demonstrated through theoretical analysis, simulations and measurements that, given their greater ability to overcome the built-in voltage of rectifying devices, high PAPR multi-sine (MS) signals are capable of more efficiently exciting energy harvesting circuits when compared to CWs. By using optimal MS signals to excite rectifying devices, remarkable RF-DC conversion efficiency gains of up to 15 dB with respect to CW signals were obtained. In order to show the effectiveness of this approach to improve the communication range of passive-backscatter systems, a MS front-end was integrated in a commercial RFID reader and a significant range extension of 25% was observed. Furthermore, a software-defined radio RFID reader, compliant with ISO18000-6C standard and with MS capability, was constructed from scratch. By interrogating passive RFID transponders with MS waveforms, a transponder sensitivity improvement higher than 3 dB was obtained for optimal MS signals. Since the amplification and transmission of high PAPR signals is critical, this work also proposes efficient MS transmitting architectures based on space power combining techniques. This thesis also addresses other not less important issues, namely self-jamming in passive RFID readers, which is the second limiting factor of passive-backscatter systems. A suitable self-jamming suppression scheme was first used for CW signals and then extended to MS signals, yielding a CW isolation up to 50 dB and a MS isolation up 60 dB. Finally, a battery-less remote control system was developed and integrated in a commercial TV device with the purpose of demonstrating a practical application of wireless power transfer and passive-backscatter concepts. This allowed battery-free control of four basic functionalities of the TV (CH+,CH-,VOL+,VOL-).No contexto da internet das coisas (IoT), onde são esperados bilhões de objetos conectados espalhados pelo planeta de forma ubíqua, torna-se impraticável uma frequente manutenção e troca de baterias dos dispositivos sem fios ubíquos. Nestes cenários, os sistemas radio backscatter passivos terão um papel preponderante dado o seu baixo custo, baixa complexidade e não necessidade de baterias nos nós móveis. Uma vez que a transmissão de energia sem fios é o principal aspeto limitativo nestes sistemas, a sua otimização tem sido um tema central de investigação, ganhando ainda mais ênfase no contexto IoT. Tradicionalmente, a transferência de energia sem-fios é feita através de sinais CW e a maximização da eficiência é conseguida através da otimização dos circuitos recetores. Neste trabalho explora-se uma abordagem fundamentalmente diferente, em que a otimização foca-se nas formas de onda em vez dos circuitos. Demonstra-se, teoricamente e através de simulações e medidas que, devido à sua maior capacidade em superar a barreira de potencial intrínseca dos dispositivos retificadores, os sinais multi-seno (MS) de elevado PAPR são capazes de excitar os circuitos de colheita de energia de forma mais eficiente quando comparados com o sinal CW tradicional. Usando sinais MS ótimos em circuitos retificadores, foram verificadas experimentalmente melhorias de eficiência de conversão RF-DC notáveis de até 15 dB relativamente ao sinal CW. A fim de mostrar a eficácia desta abordagem na melhoria da distância de comunicação de sistemas backscatter passivos, integrou-se um front-end MS num leitor RFID comercial e observou-se um aumento significativo de 25% na distância de leitura. Além disso, desenvolveu-se de raiz um leitor RFID baseado em software rádio, compatível com o protocolo ISO18000-6C e capaz de gerar sinais MS, com os quais interrogou-se transponders passivos, obtendo-se ganhos de sensibilidade dos transponders maiores que 3 dB. Uma vez que a amplificação de sinais de elevado PAPR é uma operação crítica, propôs-se também novas arquiteturas eficientes de transmissão baseadas na combinação de sinais em espaço livre. Esta tese aborda também outros aspetos não menos importantes, como o self-jamming em leitores RFID passivos, tido como o segundo fator limitativo neste tipo de sistemas. Estudou-se técnicas de cancelamento de self-jamming CW e estendeu-se o conceito a sinais MS, tendo-se obtido isolamentos entre o transmissor e o recetor de até 50 dB no primeiro caso e de até 60 dB no segundo. Finalmente, com o objetivo de demonstrar uma aplicação prática dos conceitos de transmissão de energia sem fios e comunicação backscatter, desenvolveu-se um sistema de controlo remoto sem pilhas, cujo protótipo foi integrado num televisor comercial a fim de controlar quatro funcionalidades básicas (CH+,CH-,VOL+,VOL-)

Leitor/gravador RFID: banda HF (13.56MHz)

Mestrado em Engenharia Electrónica e TelecomunicaçõesEsta dissertação surge no âmbito de uma parceria com a empresa Acronym, Informação e Tecnologia e visa o projecto e desenvolvimento de um leitor/gravador RFID para a banda HF (13.56MHz). O trabalho aqui desenvolvido centra-se essencialmente nas camadas física e MAC referentes à norma ISO14443 – Cartões de Identificação – Cartões sem contacto de proximidade. Uma vez projectado e integrado o hardware, passou-se ao desenvolvimento do firmware que implementa o protocolo ISO14443-A. Foi também criada uma interface simples (Hyperterminal/RS232) que permita ao utilizador, entre outras operações, gravar/ler blocos de dados do transponder.This Thesis is developed in cooperation with Acronym, Informação e Tecnologia Company. The main goal is project an RFID reader/writer device working in the HF band (13.56MHz). We’re working around the ISO14443-A protocol (Contactless integrated circuit(s) cards – Proximity cards) and we are focused in the Physical and Medium Access Control layer. Once all the hardware was integrated, the firmware that supports the ISO14443-A protocol was created. A simple user interface using HyperTerminal/RS232 was developed in order to allow user to access the transponder memory

Solar thermo-photocatalytic methanation using a bifunctional RuO2:TiO2/Z13X photocatalyst/adsorbent material for efficient CO2 capture and conversion

A novel bifunctional photocatalyst/adsorbent material based on the RuO2:TiO2/zeolite 13X (Z13X) composite was developed to enhance solar-driven methanation through simultaneous carbon dioxide (CO2) capture and thermo-photoconversion. The activity/stability of the hybrid material towards methane (CH4) production was assessed by varying the (i) photocatalyst composition (Ru load and semiconductor type), (ii) bifunctional material composition (photocatalyst-to-zeolite ratio) and impregnation method, (iii) illumination source and power (simulated sunlight and UVA/Visible LEDs), (iv) temperature, and (v) catalyst reuse. Additionally, adsorption equilibrium isotherms were determined to characterize the adsorption ability of the bifunctional material for both CO2 and CH4 gases. The hybrid RuO2(4.0%):TiO2(26.3%)/Z13X material (30 mg), synthesised by the solid-state impregnation method, showed the best results under simulated sunlight (0.75 W) at 150 ºC, achieving a 88% CO2 thermo-photoreduction after 100 min, corresponding to a specific CH4 production of 29.2 mmol gactive_cat−1 h−1 (309 mmol gRu−1 h−1) and apparent quantum yield of 20.7%. In adsorption equilibrium isotherms, the bifunctional material's adsorption was about 2.6-fold higher than the photocatalyst at 150 ºC, suggesting that enhanced methanation performance can be attributed to the synergistic action of CO2 capture and thermo-photoconversion.This work was supported by sources provided by: (i) national funds through Fundaç˜ao para a Ciˆencia e a Tecnologia (FCT), and Minist´erio da Ciˆencia, Tecnologia e Ensino Superior (MCTES), Portugal, in the framework of Programa de Investimento e Despesas de Desenvolvimento da Administraç˜ao Central (PIDDAC), under Project CO2-to-CH4, 2022.01176.PTDC (DOI: 10.54499/2022.01176.PTDC); and (ii) Norte Portugal Regional Operational Programme (NORTE 2020), in the framework of the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), under the project HyGreen&LowEmissions, NORTE- 01–0145-FEDER-000077. This research was also funded by (iii) FCT/ MCTES (PIDDAC): LSRE-LCM - UIDB/50020/2020 (DOI: 10.54499/ UIDB/50020/2020) and UIDP/50020/2020 (DOI: 10.54499/UIDP/ 50020/2020); and ALiCE - LA/P/0045/2020 (DOI: 10.54499/LA/P/ 0045/2020). Larissa O. Paulista acknowledges the Ph.D. fellowship supported by FCT (reference SFRH/BD/137639/2018 and COVID/BD/152922/2022). Vítor J.P. Vilar and Tˆania F.C.V. Silva acknowledges the FCT Individual Call to Scientific Employment Stimulus 2017 (CEECIND/01317/2017 and CEECIND/0138/2017).info:eu-repo/semantics/publishedVersio

Diode power detector X‐parameters™ model extraction using LSNA‐based measurement system

A study is presented on the problems that may arise when characterising low frequency device behaviour with a large signal network analyser (LSNA)-based measurement system. A diode power detector has been measured and, for the first time, an X-parameters based detector model was extracted from measurements. Difficulties measuring the detector output voltage dependence with baseband impedances, especially when those impedances showed resonant effects, were observed and a method to overcome the problems encountered is presented. The measurement-based detector X-parameters model demonstrated its usefulness to predict power detector behaviour under two-tone excitations and complex loads.Ministerio de Ciencia e Innovación | Ref. TEC2011-29264-C03-03Ministerio de Ciencia e Innovación | Ref. TEC2008-06874-C03-0

Wireless power transmission: R&D activities within Europe

Wireless power transmission (WPT) is an emerging technology that is gaining increased visibility in recent years. Efficient WPT circuits, systems and strategies can address a large group of applications spanning from batteryless systems, battery-free sensors, passive RF identification, near-field communications, and many others. WPT is a fundamental enabling technology of the Internet of Things concept, as well as machine-to-machine communications, since it minimizes the use of batteries and eliminates wired power connections. WPT technology brings together RF and dc circuit and system designers with different backgrounds on circuit design, novel materials and applications, and regulatory issues, forming a cross disciplinary team in order to achieve an efficient transmission of power over the air interface. This paper aims to present WPT technology in an integrated way, addressing state-of-the-art and challenges, and to discuss future R&D perspectives summarizing recent activities in Europe.The work of N. Borges Carvalho and A. J. S. Soares Boaventura was supported by the Portuguese Foundation for Science and Technology (FCT) under Project CREATION EXCL/EEI-TEL/0067/2012 and Doctoral Scholarship SFRH/BD/80615/2011. The work of H. Rogier was supported by BELSPO through the IAP Phase VII BESTCOM project and the Fund for Scientific Research-Flanders (FWO-V). The work of A. Georgiadis and A. Collado was supported by the European Union (EU) under Marie Curie FP7-PEOPLE-2009-IAPP 251557 and the Spanish Ministry of Economy and Competitiveness Project TEC 2012-39143. The work of J. A. García and M. N. Ruíz was supported by the Spanish Ministries MICINN and MINECO under FEDER co-funded Project TEC2011-29126-C03-01 and Project CSD2008-00068. The work of J. Kracek and M. Mazanek was supported in part by the Czech Ministry of Education Youth and Sports under Project OC09075–Novel Emerging Wireless Systems

Using X-parameters to model diode-based RF power probes

This paper presents an X-parameter model for diode power probes that can be used for calibration purposes. It will be shown that X-parameters can be applied to diode power probes with significant gains in terms of behavior characterization. This first tentative to apply X-parameters is a step further in the calibration of power probes, when they are excited by modulated signals.Xunta de Galicia | Ref. INCITE08PXIB322241 PRMinisterio de Ciencia e Innovación | Ref. TEC2008-06874-C03-0

The impact of multi-sine tone separation on RF-DC efficiency

This paper addresses the use of high PAPR multi-sine signals for efficiency increase in RF-DC converters, by evaluating the impact of tone separation, multi-sine bandwidth and circuit design in the multi-sine performance. Theoretical background is discussed and results are shown

Europe and the future for WPT

\u3cp\u3eThis article presents European-based contributions for wireless power transmission (WPT), related to applications ranging from future Internet of Things (IoT) and fifth-generation (5G) systems to high-power electric vehicle charging. The contributors are all members of a European consortium on WPT, COST Action IC1301. WPT is the driving technology that will enable the next stage in the current consumer electronics revolution, including batteryless sensors, passive RF identification (RFID), passive wireless sensors, the IoT, and machine-to-machine solutions. The article discusses the latest developments in research by some of the members of this group.\u3c/p\u3

Europe and the future for WPT: European contributions to wireless power transfer technology

Summarization: This article presents European-based contributions for wireless power transmission (WPT), related to applications ranging from future Internet of Things (IoT) and fifth-generation (5G) systems to high-power electric vehicle charging. The contributors are all members of a European consortium on WPT, COST Action IC1301. WPT is the driving technology that will enable the next stage in the current consumer electronics revolution, including batteryless sensors, passive RF identification (RFID), passive wireless sensors, the IoT, and machine-to-machine solutions. The article discusses the latest developments in research by some of the members of this group.Presented on: IEEE Microwave Magazin