pr\u00e9sentent<\/p>\n\n\n\n
Autoris\u00e9 \u00e0 pr\u00e9senter ses travaux en vue de l\u2019obtention du Doctorat de l’Institut Polytechnique de Paris, pr\u00e9par\u00e9 \u00e0 T\u00e9l\u00e9com SudParis en :<\/p>\n\n\n\n
le mardi 6 d\u00e9cembre 2022 \u00e0 10h00<\/p>\n\n\n\n
Amphi 3
T\u00e9l\u00e9com SudParis 19 Place Marguerite Perey – 91120 PALAISEAU FRANCE<\/p>\n\n\n\n
Membres du jury :<\/strong><\/p>\n\n\n\n M. Nel\u00a0SAMAMA<\/strong>, Professeur, T\u00e9l\u00e9com SudParis, FRANCE – Directeur de th\u00e8se Alors que l\u2019IoT explose, ce manuscrit retranscrit les travaux de th\u00e8se r\u00e9alis\u00e9s dans le but de poser un regard sur la faisabilit\u00e9 de substituer les piles, source d\u2019alimentation des objets connect\u00e9s par les ondes WiFi dans la bande ISM \u00e0 2.4 GHz. Cette substitution repr\u00e9sente aujourd\u2019hui un enjeu de d\u00e9veloppement durable de l\u2019IoT pour l\u2019\u00e9conomie des ressources consommables que sont les piles. Alimenter l\u2019int\u00e9gralit\u00e9 de l\u2019IoT avec des piles pourrait repr\u00e9senter jusqu\u2019\u00e0 60 millions de tonnes (0.02%) d’\u00e9mission de gaz \u00e0 effet de serre chaque ann\u00e9e. Il convient de d\u00e9finir les contraintes \u00e9nerg\u00e9tiques du syst\u00e8me qui serait uniquement aliment\u00e9 par la r\u00e9cup\u00e9ration des ondes WiFi environnantes. Des mesures de consommation \u00e9lectrique d\u2019un objet connect\u00e9 mesurant la temp\u00e9rature, la pression et l\u2019humidit\u00e9 et transmettant ces donn\u00e9es via du Bluetooth Low Energy (BLE) sont r\u00e9alis\u00e9es et sont de l\u2019ordre de 200 \u00b5J. La seconde contrainte du syst\u00e8me est la provenance de cette \u00e9nergie, i.e. la puissance des ondes WiFi. Un protocole de mesure nous permet d\u2019\u00e9tablir la puissance moyenne d\u2019\u00e9mission d\u2019un routeur WiFi \u00e0 partir d\u2019un d\u00e9bit du r\u00e9seau du routeur. Nous pourrons ainsi juger rapidement si un milieu est favorable ou non \u00e0 ce type d\u2019installation par simple mesure du d\u00e9bit. Nous avons ensuite mis en place le d\u00e9veloppement d\u2019une rectenna (rectifying antenna) afin de convertir les ondes RF WiFi en tension continue DC, i.e. une source d\u2019\u00e9nergie utilisable par l\u2019objet connect\u00e9. Au regard des campagnes de mesures que nous avons pu r\u00e9aliser sur la puissance des signaux WiFi environnants, nous estimons que le syst\u00e8me devra fonctionner avec des signaux de puissance de l\u2019ordre de -20 dBm. Nous prenons donc le pari de concevoir une rectenna reposant sur un sch\u00e9ma tr\u00e8s simple de redresseur mono alternance utilisant qu\u2019une seule diode Schottky. L\u2019\u00e9tat de l\u2019art nous conforte dans l\u2019id\u00e9e qu\u2019un sch\u00e9ma plus complexe entrainerait une chute de l\u2019efficacit\u00e9 par la faiblesse du signal. Ce convertisseur, simul\u00e9 et optimis\u00e9 via le logiciel Keysight ADS, permet alors de mesurer des tensions DC allant jusqu\u2019\u00e0 150 mV avec un signal incident RF d\u2019une puissance de -20 dBm dans la bande ISM. Cependant, 1.8 V \u00e0 3.3 V sont n\u00e9cessaires pour ce type de syst\u00e8me. Nous avons alors recours \u00e0 un \u00e9l\u00e9vateur de tension capable de fournir cette tension \u00e0 partir d\u2019une tension incidente de 20 mV. N\u00e9anmoins, un probl\u00e8me d\u2019adaptation d\u2019imp\u00e9dance avec notre convertisseur entraine une chute de tension trop importante. De plus, l\u2019\u00e9nergie r\u00e9cup\u00e9r\u00e9e en sortie du convertisseur \u00e9tant trop faible pour initier instantan\u00e9ment l\u2019\u00e9l\u00e9vation de tension, un stockage d\u2019\u00e9nergie interm\u00e9diaire est n\u00e9cessaire. Nous mettons alors en place un circuit appropri\u00e9 pour la r\u00e9cup\u00e9ration d\u2019\u00e9nergie RF qui repose sur un super condensateur entour\u00e9 d\u2019interrupteurs. Nous pouvons tant\u00f4t isoler le super condensateur avec le convertisseur pour stocker l\u2019\u00e9nergie \u00e0 une tension optimale, tant\u00f4t isoler ce super condensateur charg\u00e9 \u00e0 la bonne tension avec l\u2019\u00e9l\u00e9vateur de tension. Il agit alors dans le second cas comme une source d\u2019\u00e9nergie et permet donc la conversion. Un banc de test r\u00e9alis\u00e9 avec des interrupteurs aliment\u00e9s en externe montre le fonctionnement d\u2019une telle architecture. Notre objet connect\u00e9 est en mesure de transmettre ses donn\u00e9es au moins une fois par heure en \u00e9tant situ\u00e9 \u00e0 1 m de la borne WiFi ayant un trafic r\u00e9seau de 25 Mbps. Cet ajout d\u2019interrupteurs n\u2019est pas sans cr\u00e9er de probl\u00e8me. Ils doivent \u00eatre auto aliment\u00e9s et capables de se d\u00e9clencher sur une tension aussi faible qu\u2019une centaine de millivolts. Nous \u00e9tudions la conception de ces interrupteurs \u00e0 partir d\u2019un comparateur de tension \u00e0 base de MOSFET. Au vu de la faible tension \u00e0 surveiller, une \u00e9tude du fonctionnement \u00abshubthreshold\u00bb des MOSFET est r\u00e9alis\u00e9e pour \u00e9tablir une liste de param\u00e8tres permettant le fonctionnement du comparateur. Des futurs travaux concerneraient la possibilit\u00e9 de r\u00e9aliser de tels interrupteurs, pour obtenir un syst\u00e8me autonome.<\/p>\n\n\n\n While the IoT is exploding, this manuscript transcribes the PhD thesis work done in order to look at the feasibility of substituting batteries, power source of connected objects by WiFi waves in the ISM band at 2.4 GHz. This substitution represents today a challenge of sustainable development of the IoT for the saving of consumable resources that are batteries. Powering the entire IoT with batteries could represent up to 60 million tons (0.02%) of greenhouse gas emissions each year. The energy constraints of the system that would be powered solely by harvesting the surrounding WiFi waves need to be defined. Measurements of power consumption of a connected object measuring temperature, pressure and humidity and transmitting these data via Bluetooth Low Energy (BLE) are carried out and are of the order of 200 \u00b5J. The second constraint of the system is the source of this energy, i.e. the power of WiFi signals. A measurement protocol allows us to establish the average transmission power of a WiFi router from a network traffic flow of the router. We can thus quickly judge if an environment is favorable or not to this type of installation by simply measuring the network traffic. We then set up the development of a rectenna (rectifying antenna) in order to convert the WiFi RF waves into DC voltage, i.e. a source of energy usable by the connected object. Considering the measurements we have been able to make on the power of the surrounding WiFi signals, we estimate that the system will have to work with power signals of the order of -20 dBm. We therefore take the bet to design a rectenna based on a very simple schematic of a single-wave rectifier using only one Schottky diode. The state of the art confirms us in the idea that a more complex schematic would lead to a drop in efficiency by the weakness of the signal. This converter, simulated and optimized via the Keysight ADS software, can then measure DC voltages up to 150 mV with an incident RF signal of -20 dBm in the ISM band. However, 1.8 V to 3.3 V are required for this type of system. We then resort to a voltage booster capable of providing this voltage from an incident voltage of 20 mV. Nevertheless, an impedance matching problem with our converter leads to a too important voltage drop. Moreover, the energy harvested at the output of the converter being too weak to initiate instantaneously the rise in voltage, an intermediate energy storage is necessary. We then set up an appropriate circuit for RF energy harvesting, based on a super capacitor surrounded by switches. We can either isolate the super capacitor with the converter to store the energy at an optimal voltage, or isolate this super capacitor charged to the right voltage with the voltage booster. In the second case, it acts as a source of energy and thus allows the up-conversion. A test bench is realized with externally powered switches to show how such an architecture works. Our connected object is able to transmit its data at least once per hour while being located at 1 m from the WiFi terminal with a network traffic of 25 Mbps. This addition of switches is not without problems. They must be self-powered and capable of triggering on a voltage as low as a hundred millivolts. We study the design of these switches based on a MOSFET voltage comparator. In view of the low voltage to be monitored, a study of the \u00ab\u00a0shubthreshold\u00a0\u00bb operation of MOSFETs is carried out to establish a list of parameters allowing the operation of the comparator. Future works would concern the possibility of realizing such switches, to obtain an autonomous system.<\/p>\n","protected":false},"excerpt":{"rendered":" L’Ecole doctorale : Ecole Doctorale de l’Institut Polytechnique de Paris et le Laboratoire de recherche SAMOVAR – Services r\u00e9partis, Architectures, MOd\u00e9lisation, Validation, Administration des R\u00e9seaux pr\u00e9sentent l\u2019AVIS DE SOUTENANCE de Monsieur Florian GRANTE Autoris\u00e9 \u00e0 pr\u00e9senter ses travaux en vue de l\u2019obtention du Doctorat de l’Institut Polytechnique de Paris, pr\u00e9par\u00e9 \u00e0 T\u00e9l\u00e9com SudParis en : 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M. Aziz\u00a0BENLARBI-DELAI<\/strong>, Professeur, Sorbonne Universit\u00e9, FRANCE – Rapporteur
M. Christian\u00a0VOLLAIRE<\/strong>, Professeur des universit\u00e9s, Ecole Centrale de Lyon, FRANCE – Rapporteur
M. Adel\u00a0GHAZEL<\/strong>, Professeur, ESIGELEC, FRANCE – Examinateur
Mme Martine\u00a0VILLEGAS<\/strong>, Professeure, ESIEE Paris, FRANCE – Examinatrice
Mme Elizabeth\u00a0COLIN<\/strong>, Professeure associ\u00e9e, EFREI, FRANCE – Examinatrice
M. Bruno\u00a0DAMIEN<\/strong>, Ing\u00e9nieur, e-peas, FRANCE – Examinateur
M. Ghalid Idir\u00a0ABIB<\/strong>, Ma\u00eetre de conf\u00e9rences, T\u00e9l\u00e9com SudParis, FRANCE – Examinateur<\/p>\n\n\n\n
R\u00e9sum\u00e9 :<\/strong><\/p>\n\n\n\n
Abstract : \u00ab\u00a0Electromagnetic energy harvesting to power low power consumption connected objects\u00a0\u00bb<\/strong><\/p>\n\n\n\n