In the present thesis, I have proposed methodology of two stages Dickson charge pump, which is capable of harvesting energy at 2.45 GHz RF signal to power any low powered device. Presented design uses a simple and inexpensive circuit consisting of four microstrip patch antennas, some zero-bias Schottky diodes, Wilkinson power divider and a few passive components. Circuit was fabricated on a 60 mils RO4350B substrate (=3.66), with 1.4 mils copper conductor. Demonstration showed the charge pump provides a good performance, as it drives the low powered devices with as low as 10dBm input power at 1m away from the energy source. Thesis paper will present design techniques illustrated with data obtained on prototype circuits. The objective is to wirelessly gather energy from one RF source and convert it into usable DC power that is further applied to a set of low power electronic devices. Radio Frequency Identification (RFID) tag system could also be improved using this method. RF-to-DC conversion is accomplished by designing and characterizing an element commonly known as a Rectenna, which consists of an antenna and an associated rectification circuitry. The rectenna is fully characterized in this dissertation and is used for charging low powered devices.

Novel techniques for high-performance wireless power transmission and data interfacing with implantable medical devices (IMDs) were proposed. Several system- and circuit-level techniques were developed towards the design of a novel wireless data and power transmission link for a multi-channel inductively-powered wireless implantable neural-recording and stimulation system. Such wireless data and power transmission techniques have promising prospects for use in IMDs such as biosensors and neural recording/stimulation devices, neural interfacing experiments in enriched environments, radio-frequency identification (RFID), smartcards, near-field communication (NFC), wireless sensors, and charging mobile devices and electric vehicles. The contributions in wireless power transfer are the development of an RFID-based closed-loop power transmission system, a high-performance 3-coil link with optimal design procedure, circuit-based theoretical foundation for magnetic-resonance-based power transmission using multiple coils, a figure-of-merit for designing high-performance inductive links, a low-power and adaptive power management and data transceiver ASIC to be used as a general-purpose power module for wireless electrophysiology experiments, and a Q-modulated inductive link for automatic load matching. In wireless data transfer, the contributions are the development of a new modulation technique called pulse-delay modulation for low-power and wideband near-field data communication and a pulse-width-modulation impulse-radio ultra-wideband transceiver for low-power and wideband far-field data transmission.

Στα κεφάλαια που ακολουθούν παρατίθενται στοιχεία για το δίκτυο υψηλής και υπερυψηλής τάσης της Δυτικής Ελλάδας. Τα στοιχειά αυτά καλύπτουν ένα διάστημα 14 ετών. Γίνεται επεξεργασία των στοιχείων αυτών με στόχο να αξιολογηθεί η λειτουργία της γραμμής σε σύγκριση με τις προδιαγραφές κατασκευής.Επίσης εξάγονται και αλλά χρήσιμα συμπεράσματα ακόμα και για τις μεθόδους που χρησιμοποιούνται για την αξιολόγηση της λειτουργίας του δικτύου γενικότερα. Στο 1ο κεφάλαιο αναφέρονται τα είδη σφαλμάτων(χωρίζονται σε κατηγορίες με βάση τη χρονική τους διάρκεια και τις επιπτώσεις αυτών στο δίκτυο) που παρουσιάζονται στις γραμμές και γίνεται επεξεργασία αυτών. Οι κατηγορίες των σφαλμάτων είναι • Παροδικά • Παραμένοντα • Μόνιμα Τα κριτήρια κατηγοριοποίησης είναι η διάρκεια των σφαλμάτων και το ύψος της ζημιάς που προκαλούν. Βέβαια οι δυο αυτές ποσότητες είναι αλληλένδετες και ανάλογες. Μια ζημιά που θα καταστρέψει παραδείγματος χάρη έναν πυλώνα θα διαρκέσει ως βλάβη, στην καλύτερη περίπτωση, μερικές μέρες. Έτσι τα παροδικά σφάλματα διαρκούν το πολύ μερικά δευτερόλεπτα και το δίκτυο στο οποίο εμφανίζεται το σφάλμα επανέρχεται σε λειτουργία από μόνο του, δίχως την ανάγκη παρέμβασης. Τα μόνιμα σφάλματα είναι τα σοβαρότερα και τα πλέον απευκταία. Απαιτούν την παρέμβαση συνεργείου της Δ.Ε.Η. στη συντριπτική πλειονότητα των περιπτώσεων τους. Τα παροδικά είναι τα σφάλματα με χαρακτηριστικά κάπου ενδιάμεσα των δυο προηγούμενων κατηγοριών. Στο 2ο κεφάλαιο παρουσιάζονται τα αιτία που προκαλούν τα σφάλματα στις γραμμές και γίνεται εκτενέστερη αναφορά στις ατμοσφαιρικές υπερτάσεις. Όσον αφορά τις τελευταίες ακολουθεί μέσα στο κεφάλαιο ποιοτικη και ποσοτική ανάλυση των δεδομένων. Η πλειονότητα των σφαλμάτων προκαλείται εξαιτίας κακών ατμοσφαιρικών συνθηκών. Με τον όρο αυτό στη συγκεκριμένη περίπτωση εννοούμε κυρίως τα κεραυνικά πλήγματα πάνω σε μια γραμμη ή πολύ κοντά σε αυτή. Αρκετά πιο σπάνια μπορεί να προκαλέσει σοβαρό σφάλμα σε μια γραμμη ο δυνατός αέρας. Όχι πως και αυτό το ενδεχόμενο είναι απίθανο. Είναι δυνατό ο αέρας με την άσκηση δύναμης πάνω σε μια γραμμη είτε με άμεσο είτε με έμμεσο τρόπο (να ξεριζώσει ένα δέντρο και αυτό να πέσει πάνω στη γραμμη ) να προκαλέσει σοβαρή ζημιά στη γραμμη. Παρατηρείται πως ο αριθμός των σφαλμάτων εμφανίζει ομαλές αυξομειώσεις εκτός εξαιρετικών περιπτώσεων , όπως αποτελεί στην περίπτωση μας το έτος 1993 κατά το οποίο αυξάνονται ραγδαία τα σφάλματα ενώ το αμέσως επόμενο έτος επανέρχονται στα προ δυο ετών επίπεδά τους. Στο 3ο κεφάλαιο γίνεται σύντομη αναφορά στο κλίμα της Ελλάδας , στην κεραυνική συχνότητα και σε βασικά χαρακτηριστικά των γραμμών και των πυλώνων στο υπό εξέταση δίκτυο. Το κλίμα της Ελλάδος βέβαια δεν είναι ανεξάρτητο του κλίματος σε παγκόσμια κλίμακα. Επομένως , συνυπολογίζοντας τα δεδομένα που έχουν διαμορφωθεί τα τελευταία χρόνια με τις απότομες διακυμάνσεις του καιρού, είναι φυσιολογικό κάποιες παραδοχές που έχουμε κάνει στα πλαίσια της εργασίας αυτής να μην επιβεβαιώνονται πάντα. Ο χάρτης ισοκεραυνικών καμπύλων που παρατίθεται είναι μέρος του παγκοσμίου χάρτη ισοκεραυνικών καμπύλων. Και σε αυτήν την περίπτωση έχουν γίνει κάποιες παραδοχές και γενικεύσεις από τους επιστήμονες που έχουν σχεδιάσει αυτούς τους χάρτες και είναι λογικό να παρουσιάζονται αποκλίσεις στην πραγματικότητα. Τέλος τα χαρακτηριστικά του δικτύου είναι μια ευγενική παραχώρηση της Δ.Ε.Η. όπως βέβαια και όλα τα στοιχειά που εξετάζουμε. Στο 4ο κεφάλαιο παρουσιάζεται η μέθοδος ANACOM η οποία θα χρησιμοποιηθεί για την εξαγωγή θεωρητικών δεδομένων , τα οποία θα αντιπαρατεθούν στη συνέχεια με τα πραγματικα. Η μέθοδος αυτή είναι μια εξέλιξη παλαιοτέρων μεθόδων και χρησιμοποιείται ευρύτατα σε θέματα σφαλμάτων γραμμών μεταφοράς ρεύματος. Επίσης υπολογίζει τα σφάλματα θωράκισης καθώς και τα ανάστροφα σφάλματα. Κατά τον υπολογισμό των σφαλμάτων πρέπει να λάβουμε υπόψη μας πολλούς παράγοντες όπως αριθμό μονωτήρων ,αντίσταση γείωσης πυλώνων ,τάση δικτύου ,αριθμό αγωγών προστασίας ,ημέρες καταιγίδας ,μήκος της γραμμής αλλά ταυτόχρονα κάνουμε και ορισμένες παραδοχές όπως το ποσοστό των κεραυνών που παρακάμπτουν τον αγωγό προστασίας και πλήττουν τη γραμμη. Στο 5ο κεφάλαιο παρατίθεται αναλυτικά ο υπολογισμός σφαλμάτων σε όλα τα τμήματα του δικτύου. Το υπό εξέταση δίκτυο χωρίζεται σε μεγάλο αριθμό μικρότερων τμημάτων. Ακόμα και στην περίπτωση που το δίκτυο έχει ακριβώς τα ίδια χαρακτηριστικά εκατέρωθεν , ας πούμε , ενός υποσταθμού ,πάλι υπολογίζουμε ξεχωριστά τα αναμενομενα σφάλματα. Η τμηματοποίηση αυτή είναι απαραίτητη κυρίως γιατί έτσι είναι καταγεγραμμένα τα στοιχειά που έχουμε λάβει από τη Δ.Ε.Η.. Το κεφάλαιο αυτό είναι καθαρά υπολογιστικό αλλά είναι απολύτως απαραίτητο για να γίνει η περαιτέρω επεξεργασία των στοιχείων. Στο 6ο κεφάλαιο αναλύεται και εξηγείται η απόκλιση μεταξύ αναμενόμενων και πραγματικών σφαλμάτων. Στο τελικό αποτέλεσμα παρατηρούμε μια πολύ σημαντική απόκλιση μεταξύ των αναμενόμενων και των πραγματικών σφαλμάτων. Η απόκλιση αυτή έχει διάφορες αιτίες που την προκαλούν : • Όπως προαναφέραμε έχουν γίνει κάποιες παραδοχές και στρογγυλοποιήσεις οι τιμές των οποίων είναι πάντα μεγαλύτερες της μέσης εκτιμημένης. • Αρκετά τμήματα της γραμμής τέμνουν περισσότερες από μια ισοκεραυνικές καμπύλες. Αφενός είναι εξαιρετικά δύσκολο να βρούμε το ακριβές νούμερο ‘ήμερων καταιγίδας ‘ αφετέρου είναι προτιμότερο οποιαδήποτε στρογγυλοποίηση να μη γίνει χαμηλότερα του επιπέδου μέσης τιμής αλλά υψηλοτέρα αυτής αφού ασχολούμαστε με την προστασία πολύ ακριβών συσκευών και ενός κοινωνικού αγαθού όπως είναι το ηλεκτρικό ρεύμα. • Η τιμή της αντίστασης των πυλώνων θεωρείται σταθερή για όλο το μήκος κάθε τμήματος. Αυτό είναι ιδιαίτερα απίθανο. Η τιμή της αντίστασης του εδάφους μεταβάλλεται σε απόσταση μερικών μέτρων πόσο δε μάλλον σε αποστάσεις εκατοντάδων μέτρων όπως είναι το άνοιγμα μεταξύ των πυλώνων. Επίσης η ειδική τιμή της αντίστασης εδάφους μεταβάλλεται και κατά τη διάρκεια ενός έτους κυρίως λόγω της μεταβολής της υγρασίας του εδάφους. • Τέλος δεν πρέπει να ξεχνάμε ότι αναφερόμαστε σε ανθρώπινες κατασκευές οπότε δεν είναι εφικτό να πετύχουμε ακριβώς τα ίδια χαρακτηριστικά. Στο 7ο κεφάλαιο τέλος αναπτύσσεται διεξοδικότερα και με τη χρήση παραδείγματος ,ο ρόλος που παίζει η διαδρομή της γραμμής ( routing ) στην αντικεραυνική συμπεριφορά των γραμμών υψηλής τάσης. Το παράδειγμα σύγκρισης που παρατίθεται (Αχελώος- Δίστομο και Αχελώος – Πουρνάρι )είναι χαρακτηριστικό γιατί αφορά δυο τμήματα του δικτύου με πολλά κοινά χαρακτηριστικά. Ίδια τιμή αντίστασης γείωσης , ίδιο αριθμό πυλώνων , ίδια τάση μεταφοράς ,ίδιο τύπο και αριθμό αγωγών. Συν τοις άλλοις τα δυο αυτά τμήματα έχουν κοινό σημείο ‘ εκκίνησης’ τον Αχελώο απλά έχουν αντίθετες κατευθύνσεις. Οι μοναδικές διαφορές είναι τα μήκη των τμημάτων και ο αριθμός των ήμερων καταιγίδας,παράγοντες οι οποίοι βέβαια συνυπολογίζονται στη θεωρητική εκτίμηση των σφαλμάτων. Στην πράξη όμως αποδεικνύεται μια απόκλιση 15% υπέρ της γραμμής που είναι κατασκευασμένη σε πιο προστατευμένο περιβάλλον(Αχελώος – Δίστομο). Βρίσκεται σε πλαγιές ορεινών όγκων και όχι σε πεδιάδες. Επίσης κανένα κομμάτι δεν διέρχεται από κορυφή βουνού όπως συμβαίνει αναγκαστικά στη δεύτερη περίπτωση. / In the capitals that follow are mentioned elements for the high voltage network of Western Greece. The elements cover one interval of 14 years. A treatment of these elements in order to evaluate the operation of line compared to its construction specifications. There are also exported useful conclusions even on the methods that are used for the evaluation of operation of network in general. In the 1st chapter are reported the types of faults (are separated in categories with base their time duration and the repercussions of these in the network) that are presented in the lines and takes place treatment of these. The categories of faults are • Transitory • Remaining the • Permanently The criteria of categorization are the duration of faults and the height of damage that they cause. Of course these two quantities are interrelated and proportional. A damage that will destroy for example pylon will last as damage, in better, case certain days. Thus the transitory faults lasts at maximum certain seconds and the network in which is presented the fault is back on line on his own, without the need of intervention. The permanent faults are most serious. They require the intervention of repair crew of Δ.Ε.Η. in the overwhelming majority of their cases. Transitory are the faults with characteristically somewhere in-between the two previous categories. In the 2nd chapter are presented the reason that cause the faults in the lines and becomes a more extensive report in the atmospheric hypertensions. With regard to the last ones follows in to the capital, qualitative and quantitative analysis of data. The majority of faults are caused because of the bad atmospheric conditions. With this term in the particular case we mainly mean the thunder strokes on a line or a lot near it. Enough more seldom it can cause serious fault in a line the strong air wind. It is possible the wind with the exercise of force on a line either with direct or with indirect way (it eradicates a tree and this it falls on the line) will cause serious damage in the line. It is observed that the number of faults presents smooth fluctuations except exceptional cases, as it constitutes in our case the year 1993 at which are increased rapidly the faults while the immediately next year falls down in the two years ago levels. In the 3rd chapter follows short report in the climate of Greece, in the thunder frequency and in basic characteristics of lines and pylons in the network under review. The climate of Greece of course is not independent of the climate in world scale. Consequently, taking under consideration the data that have been shaped in the past few years with the abrupt fluctuations of climate, it is logical that certain admissions that we have made in the frames of this work will not always be confirmed. The map of thunder density that is presented is part of a similar world map. In this case also there have been certain admissions and generalizations from the scientists that have drawn these maps and are the reason that are presented divergences in reality. Finally the characteristics of network are a polite concession of Δ.Ε.Η. as of course and the data that we examine. In the 4th chapter is presented the method ANACOM which will be used for the export of theoretical data, which afterwards will be compared with real data. This method is a development of older methods and is used very widely on issues concerning the faults in current transport lines. Also it calculates the faults of armoring as well as the backstroke faults. At the calculation of faults we should take into consideration a lot of factors such as number the ground resistance of pylons, the voltage of the network, the number of protection conductors, the days of storm, the length of line but simultaneously we must make certain admissions as the percentage the lightings that surpass the protection line and strike the line. In the 5th chapter is mentioned analytically the calculation of faults in all the departments of the network. The network under review is separated in a large number of smaller departments. Even in the case where the network has precisely the exact same characteristics at both sides, for example, of a substation, nevertheless we calculate separately the expected faults. This segmentation is essential mainly because thus it is organized the database that we have received from Δ.Ε.Η.. This capital is clearly a calculating one but is absolutely essential in order to precede the further analysis of data. In the 6th chapter is analyzed and is explained the divergence between expected and occurred faults. In the final conclusion we observe a very important divergence between the expected also real faults. This divergence has various reasons that cause it: As we mentioned before there have been certain admissions and approximations of the values. Enough departments of line go through from more than one thunder map lines. On one side it is exceptionally difficult to find a precise number `of days of storm ` on the other hand it is preferable any approximation not to lower than the level of medium price but greater than this considering that we deal with the protection of very expensive appliances and a social good such as the electric current. The level of resistance of pylons is considered constant for all the length of each department. This is particularly improbable. The price of resistance of ground is altered in distance of certain meters not to mention in distances of hundreds of meters as is the opening between the pylons. In the 7th chapter is developed more extensively with the use of example, the role that plays the path of the line (routing) in the protection of lines of high voltage. The example of comparison that is mentioned (Acheloos Distomo and Acheloos - Poyrnari) is characteristic because it concerns two departments of network with a lot of common characteristics. Same price of ground resistance, same number of pylons, same voltage level, same type and number of conductors. Plus this two departments have common point `of departure' Acheloos and simply have opposite directions. The sole differences are the lengths of departments and the number of days of storm, factors which of course are included in the theoretical estimate of faults. Into practice however is proved a divergence 15% in favor of the line that is manufactured in more protected environment (Acheloos - Distomo). It is found in the side of mountains and not in plains.

In the present thesis, I have proposed methodology of two stages Dickson charge pump, which is capable of harvesting energy at 2.45 GHz RF signal to power any low powered device. Presented design uses a simple and inexpensive circuit consisting of four microstrip patch antennas, some zero-bias Schottky diodes, Wilkinson power divider and a few passive components. Circuit was fabricated on a 60 mils RO4350B substrate (=3.66), with 1.4 mils copper conductor. Demonstration showed the charge pump provides a good performance, as it drives the low powered devices with as low as 10dBm input power at 1m away from the energy source. Thesis paper will present design techniques illustrated with data obtained on prototype circuits. The objective is to wirelessly gather energy from one RF source and convert it into usable DC power that is further applied to a set of low power electronic devices. Radio Frequency Identification (RFID) tag system could also be improved using this method. RF-to-DC conversion is accomplished by designing and characterizing an element commonly known as a Rectenna, which consists of an antenna and an associated rectification circuitry. The rectenna is fully characterized in this dissertation and is used for charging low powered devices.

This thesis presents an investigation into the power transmission limitations imposed on a VSC-HVdc converter by ac system strength and ac system impedance characteristics, quantified by the short circuit ratio (SCR). An important result of this study is that the operation of the converter is not only affected by the SCR’s magnitude, but is also significantly affected by the ac system’s impedance angle at the fundamental frequency. As the ac impedance becomes more resistive, the minimum SCR required at the rectifier side increases from that required for ideally inductive ac impedance, but it decreases at the inverter side. The finite megavolt ampere (MVA) limit of the VSC imposes a further limitation on power transfer, requiring an increase in the value of the minimum SCR. This limitation can be mitigated if additional reactive power support is provided at the point-common-connection. A state-space VSC model was developed and validated with a fully detailed non-linear EMT model. The model showed that gains of the phased-locked-loop (PLL), particularly at low SCRs greatly affect the operation of the VSC-HVdc converter and that operation at low SCRs below about 1.6 is difficult. The model also shows that the theoretically calculated power-voltage stability limit is not attainable in practice, but can be approached if the PLL gains are reduced. The thesis shows that as the VSC-HVdc converter is subject to large signal excitation, a good controller design cannot rely on small signal analysis alone. The thesis therefore proposes the application of optimization tools to coordinate the controls of multiple converters in a dc grid. A new method, the "single converter relaxation method", is proposed and validated. The design procedure of control gains selection using the single converter relaxation method for a multi-converter system is developed. A new method for selecting robust control gains to permit operation over a range of operation conditions is presented. The coordination and interaction of control parameters of multi-terminal VSC are discussed. Using the SCR information at converter bus, the gain scheduling approach to optimal gains is possible. However, compared to robust control gains setting, this approach is more susceptible to system instability.

This thesis presents an investigation into the power transmission limitations imposed on a VSC-HVdc converter by ac system strength and ac system impedance characteristics, quantified by the short circuit ratio (SCR). An important result of this study is that the operation of the converter is not only affected by the SCR’s magnitude, but is also significantly affected by the ac system’s impedance angle at the fundamental frequency. As the ac impedance becomes more resistive, the minimum SCR required at the rectifier side increases from that required for ideally inductive ac impedance, but it decreases at the inverter side. The finite megavolt ampere (MVA) limit of the VSC imposes a further limitation on power transfer, requiring an increase in the value of the minimum SCR. This limitation can be mitigated if additional reactive power support is provided at the point-common-connection. A state-space VSC model was developed and validated with a fully detailed non-linear EMT model. The model showed that gains of the phased-locked-loop (PLL), particularly at low SCRs greatly affect the operation of the VSC-HVdc converter and that operation at low SCRs below about 1.6 is difficult. The model also shows that the theoretically calculated power-voltage stability limit is not attainable in practice, but can be approached if the PLL gains are reduced. The thesis shows that as the VSC-HVdc converter is subject to large signal excitation, a good controller design cannot rely on small signal analysis alone. The thesis therefore proposes the application of optimization tools to coordinate the controls of multiple converters in a dc grid. A new method, the "single converter relaxation method", is proposed and validated. The design procedure of control gains selection using the single converter relaxation method for a multi-converter system is developed. A new method for selecting robust control gains to permit operation over a range of operation conditions is presented. The coordination and interaction of control parameters of multi-terminal VSC are discussed. Using the SCR information at converter bus, the gain scheduling approach to optimal gains is possible. However, compared to robust control gains setting, this approach is more susceptible to system instability.

Wireless backhaul communication and power transfer can make the deployment of outdoor small cells (SCs) more cost effective; thus, their rapid densification can be enabled. For the first time, solar cells can be leveraged for the two-fold function of energy harvesting (EH) and high speed optical wireless communication. In this thesis, two complementary concepts for power provision to SCs are researched using solar cells – the optical wireless power transfer (OWPT) in the nighttime and solar EH during daytime. A harvested power of 1W is considered to be required for an autonomous SC operation. The conditions of darkness – worst case scenario – are initially selected, because the SC needs to harvest power in the absence of ambient light. The best case scenario of daytime SC EH from sunlight is then explored to determine the required battery size and the additional power from optical sources. As a first approach, an indoor 5m experimental link is created using a white light-emitting diode for OWPT to an amorphous silicon (Si) solar panel. Despite the use of a large mirror for collimation, the harvested power and energy efficiency of the link are measured to be only 18:3mW and 0:1%, respectively. Up to five red laser diodes (LDs) with lenses and crystalline Si (c-Si) cells are used in a follow-up study to increase the link efficiency. A maximum power efficiency of 3:2% is measured for a link comprising two LDs and a mono-c-Si cell, and the efficiency of all of its components is determined. Also, the laser system is shown to achieve an improvement of the energy efficiency by 2:7 times compared with a state-of-the-art inductive power transfer system with dipole coils. Since the harvested power is only 25:7mW, an analytical model for an elliptical Gaussian beam is developed to determine the required number of LDs for harvesting 1W; this shows an estimated number of 61 red LDs with 50mW of output optical power per device. However, a beam enclosure of the developed Class 3B laser system of up to a 3:6m distance is required for eye safety. A simulation study is conducted in Zemax for the design of an outdoor 100m infrared wireless link able to harvest 1W under clear weather conditions. Harvesting 1:2W and meeting eye safety regulations for Class 1 are shown to be feasible by a 1550 nm laser link. The required number of laser power converters is estimated to be 47 with an area of 5 5mm2 per device. Also, the dimensions of the transmitter and receiver are considered to be acceptable for the practical application of SC EH. In the last part of this thesis, two multi-c-Si solar panels are initially used for EH in an outdoor environment during daytime. The power supply of at least 1W is shown to be achievable during hour periods under sunny and cloudy conditions. A maximum average power of 4:1W is measured in the partial presence of clouds using a 10W solar panel. Since the variability of weather conditions induces the harvested power to fluctuate with values of mW, the use of optical sources is required in periods of insufficient solar EH for SCs. Therefore, a hybrid solar/laser based EH design is proposed for a continuous annual SC provision of 1Win ‘darker’ places on earth such as Edinburgh, UK. The 10W multi-c-Si solar panel and the 1550 nm laser link are considered; thus, the feasibility of supplying the SC with at least 1Wper hour monthly using a battery with energy content of only 60Wh is shown through simulations. A maximum monthly average harvested power of 824mW is shown to be required by the 1550 nm laser system that has already been overachieved through simulations in Zemax.

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.

A Transferência Indutiva de Potência (TIP) é uma maneira de se realizar transferência de energia elétrica sem fio e tem se popularizado atualmente por conta da comodidade e segurança que ela proporciona. Esta dissertação apresenta o estudo de um sistema TIP para recarga de baterias e existem vários desafios que devem ser superados nesta área. Um deles é a metodologia de projeto dos indutores primário e secundário, pois não é uma tarefa trivial encontrar uma relação entre parâmetros geométricos, elétricos e magnéticos. Diante deste fato este trabalho apresenta e aperfeiçoa uma metodologia de projeto utilizando uma ferramenta computacional gratuita baseada no método dos elementos finitos. Os resultados experimentais demonstram que o método é válido e a ferramenta é adequada não somente para o projeto dos indutores, mas também para análise do comportamento dos mesmos diante de desalinhamentos espaciais. Além disso, é apresentado o funcionamento básico de dois conversores muito utilizados em TIP e o estado da arte das malhas ressonantes, cuja função é minimizar a energia reativa consumida nos circuitos primário e secundário. Em seguida são discutidas técnicas de estimação de tensão e corrente na carga utilizando medidas de tensão e/ou corrente em elementos do circuito primário. Essas técnicas são importantes, pois permitem a utilização apenas do controlador presente no circuito primário e isto implica na redução dos custo e complexidade do sistema TIP. Durante o estudo verificou-se na literatura que não existia uma técnica de estimação para o sistema TIP adotado neste trabalho e portanto, foi necessário desenvolver uma nova proposta de estimador. Os resultados de simulação demonstram que o estimador possui um bom desempenho mesmo diante de variações do coeficiente de acoplamento e da resistência na carga e é portanto adequado para situações em que é necessário realizar recarga de baterias com TIP. / Inductive Power Transfer (IPT) is a way to conduct wireless power transfer and has become popular today because of the convenience and security it provides. This dissertation presents the study of a IPT system for battery recharging and there are several challenges that must be overcome in this area. One of them is the design methodology of the primary and secondary inductors, since it is not a trivial task to find a relation between geometric, electric and magnetic parameters. In view of this fact, this work presents and improves a project methodology using a free computational based on the finite element method. The experimental results demonstrate that the method is valid and the tool is suitable not only for the design of the inductors, but also for the analysis of their behavior in face of spatial misalignments. In addition, this dissertation presents the basic operation of two widely used IPT converters and the state of the art of compensations networks, whose function is to minimize the reactive energy consumed in the primary and secondary circuits. Next, load voltage and load current estimation techniques are discussed using voltage and/or current measurements on elements of the primary circuit. These techniques are important because they allow the use of a single controller in the primary circuit, reducing the cost and complexity of the IPT system. During the study, it was verified in the literature the inexistence of a estimation technique for the IPT system adopted in this work and therefore, it was necessary to propose and develop a new estimator. The simulation results show that the proposed estimator performs well even in the case of variations in the coupling coefficient and load resistance and is therefore suitable for situations where it is necessary to recharge IPT batteries.

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.