A novel method of current sensing using resistance of power delivery path is introduced as a mean to measure static or dynamic load current in high-power system-on-chips, where conventional methods deemed inadequate. It is named ???IRS??? here, and it stands for Inherent Resistance Current Sensing. To explain its application and to provide motivation beyond this work, pros and cons of conventional techniques are reviewed with a look at previous works done in this area. It is followed with review of discreet implementation of the sensor (IRS) in chapter three. The measurements results collected using the discrete circuits are included with an in-depth analysis of the results and compensation techniques. It offers insight to effectiveness of the solution and its potential, while highlighting shortcomings and limitation of discrete implementation. This would set the tone to design integrated version of the sensor. In order to select amplifier architecture, a rundown of common methods to construct the instrumentation amplifier is discussed in chapter 4, primarily based on the latest work already done in this field per cited references. This is to help readers to get an overall view of the challenges and techniques to overcome them. Finally, the architecture for the integrated version of the sensor (IRS) is presented, with a proof of concept design. The design is targeted for low voltage VLSI systems to allow integration within large SoCs such as GPUs and CPUs. The primary block, the instrumentation amplifier, is constructed using rail-to-rail current conveyers and simulated using TSMC 32nm process node. The simulation results are analyzed and observations are provided.

A novel method of current sensing using resistance of power delivery path is introduced as a mean to measure static or dynamic load current in high-power system-on-chips, where conventional methods deemed inadequate. It is named “IRS” here, and it stands for Inherent Resistance Current Sensing. To explain its application and to provide motivation beyond this work, pros and cons of conventional techniques are reviewed with a look at previous works done in this area. It is followed with review of discreet implementation of the sensor (IRS) in chapter three. The measurements results collected using the discrete circuits are included with an in-depth analysis of the results and compensation techniques. It offers insight to effectiveness of the solution and its potential, while highlighting shortcomings and limitation of discrete implementation. This would set the tone to design integrated version of the sensor. In order to select amplifier architecture, a rundown of common methods to construct the instrumentation amplifier is discussed in chapter 4, primarily based on the latest work already done in this field per cited references. This is to help readers to get an overall view of the challenges and techniques to overcome them. Finally, the architecture for the integrated version of the sensor (IRS) is presented, with a proof of concept design. The design is targeted for low voltage VLSI systems to allow integration within large SoCs such as GPUs and CPUs. The primary block, the instrumentation amplifier, is constructed using rail-to-rail current conveyers and simulated using TSMC 32nm process node. The simulation results are analyzed and observations are provided.

Researchers at Uppsala University are developing a flywheel energy storage device intended to be used in electrical vehicles. Kinetic energy storage technology has potential to make purely electric powertrain both more effective and efficient. While deployment of the third prototype is approaching there has been a request for a more precise and noise-immune circuitry to power active magnetic bearings that hold and stabilise the rotor. A similar circuit designed for powering electromagnets was recently developed at the Uppsala University’s Electricity department and is used as a template in development of the new active magnetic bearing driver circuit. Current measurement integration technique is tested and implemented as a way to increase circuit’s control feedback loop performance. To further boost precision and noise-immunity 0-20 mA current loop signals are adapted as the standard for output signals. Results of this project include a thorough analysis of the electromagnet driver circuit development, implementation of a new current sensing technique including an experimental self-inductance measurement, printed circuit board layout design and a full list of components necessary to power and control two sets of active magnetic bearings consisting of 8 individual electromagnets.

No description available.

- / In the present diplomatic project is realised a process of measurements of the leakage current by the system of measurement that was manufactured by gentleman Sideraki, in the frames of his doctoral thesis. The measurements were realised in the substation 150 kV of Crete‟s system of transport and in the substation 150 kV of A.I.S. Linoperamaton. In the first chapter, is presented the phenomenon of the insulators‟ pollution, while it constitutes the prime cause of the leakage current. Here are presented the main causes of pollution, its unfavourable results as well as her ways of confrontation. There is an extensive report, in the use of multilateral insulators and multilateral coatings for the confrontation of the phenomenon of pollution. Particularly is stressed the hydrophobic characteristic of these materials which leads to the reduction of the quantity of pollution on the surface of the insulators. The second chapter, is a presentation of the work of various researchers over the world, in the effort of studying the leakage current and its connection with the phenomena of ageing and flashover. Also there are mentioned the experimental provisions that they used in the frames of their studies and are reported the mainer conclusions to which they were led. Common point of their conclusions constitutes the make of ascertainment that the biggest price of the leakage current, constitutes an unreliable indicator of description of the distressed insulator‟s surface, since important information on the situation of the surface we draw also from the waveform of the leakage current. In the third chapter there is a concise presentation of Fourier„s theory and transforming, while an extensive report in the distinguishable Fourier transforming (DFT) is also mentioned. Finally, is presented the fast Fourier transforming (FFT), which constitutes an algorithm of fast calculation of distinguishable transformation Fourier and is used among others for the spectrum analysis of signals of distinguishable time. In the fourth chapter, is realised the treatment of measurements, with the use of Labview for the study of the leakage current in the field of frequency. Leakage current‟s waveforms are categorized, with criteria, the lack of linearity and the presence of discharges or not and conclusions are exported on these waveforms, from their spectrum analysis.

La mesure des champs électromagnétiques très basses fréquences en mer est utilisée pour de nombreuses applications, dont les principales sont militaires et géophysiques. Les besoins pour ces applications sont des capteurs capables d'effectuer des mesures à très basses fréquences avec un niveau de bruit inférieur au nV.m^(-1).Hz^(-1/2).Les électromètres commerciaux et académiques utilisés actuellement pour la mesure des champs électriques en mer sont à mesure de tension. Leur inconvénient majeur est une remontée de bruit aux basses fréquences, due à l'électronique d'amplification du signal. Une autre méthode de mesure des champs électriques en mer consiste à mesurer le courant traversant un dispositif de faible impédance. Nous avons conçu un électromètre à mesure de courant et magnétomètre au sein du même capteur, en essayant de pallier les défauts des électromètres passés et actuels.Dans un premier temps, nous décrivons le milieu dans lequel le capteur sera amené à fonctionner, puis les applications auxquelles il est destiné, et enfin l'état de l'art des capteurs existant et leurs limites.Nous décrivons ensuite de manière détaillée le comportement du capteur. En particulier, nous déterminons par simulation et de manière expérimentale les différentes fonctions de transfert du capteur, en fonction de ses caractéristiques géométriques et de son environnement.Après avoir présenté plusieurs architectures possibles d'électromètres répondant aux objectifs fixés, nous utilisons les résultats obtenus au chapitre précédent pour dimensionner un électromètre dont la conductivité équivalente n'est pas forcément égale à celle de l'eau de mer. Ce degré de liberté supplémentaire par rapport aux contraintes de conception des électromètres à mesure de courant passés permet d'améliorer les performances du capteur. Enfin nous proposons deux méthodes de calibration de l'électromètre, sans connaissance a priori de son environnement.Enfin nous caractérisons les différents éléments d'un prototype de laboratoire, et nous présentons les résultats des tests de ce prototype complet. / The measurement of electric and magnetic fields at sea is of great interest for many applications (geophysics, oil prospection, vessels detection, etc.) In all cases, measurements at very low frequency with a very low noise are required.Most marine electrometers measure the potential difference between two separated electrodes. Their noise level is very good but increases when frequency decreases, due to amplification electronics. Another type of electrometers is based on a low impedance current measurement system. We designed a current based electrometer, which is as well able to simultaneously measure the magnetic field, trying to solve the problems of former devices.First, we describe the medium in which the sensor will be used, the applications for which it is intended, and the state of the art of existing sensors and their defects.We then describe in detail the behavior of the sensor. In particular, we determine by simulation and experimentally the different transfer functions of the sensor, depending on its geometrical characteristics and its environment.After presenting several potential architectures of electrometers meeting the targets, we use the results obtained in the previous chapter to scale an electrometer, whose equivalent conductivity is not necessarily equal to that of seawater. This additional degree of freedom in comparison with the design constraints of the former current measurement electrometers enables us to improve the performance of the sensor. Finally we propose two calibration methods of the electrometer, without prior knowledge of its environment.Finally we characterize the different elements of a laboratory prototype, and we present the results of the tests of the complete prototype.

Mesurer des forts courants alternatifs sur une large bande de fréquences est primordial pour de nombreuses applications dont la surveillance du réseau de distribution électrique et le développement des véhicules électriques. Dans le premier cas, la mesure du courant est nécessaire pour quantifier la qualité du réseau en présence d’harmoniques provenant des énergies renouvelables intermittentes dont le spectre en fréquences est assez large (plusieurs centaines de kilohertz). Dans le second cas, la mesure du courant (jusqu’à plusieurs dizaines d’ampères) intervient dans la quantification du rendement de la chaîne de traction d’un moteur électrique : dans la mesure du courant la prise en compte d’un grand nombre d’harmoniques (jusqu’à 1 MHz) est indispensable pour garantir une connaissance précise du rendement du moteur. Des résistances de faibles valeurs, appelées « shunt », sont alors indispensables pour mesurer des forts courants. Les shunts sont largement utilisés comme étalon de résistance dans les laboratoires de métrologie et les instruments de précision. Leur utilisation nécessite la connaissance préliminaire en fonction de la fréquence des deux paramètres suivants : déphasage de l’impédance du shunt ; variation relative du module de l’impédance du shunt par rapport à la sa valeur de sa résistance en courant continu, ce paramètre est appelé “écart de transposition”. Pour un niveau de courant de 10 A, l’impédance des shunts existants présente de fortes variations en module et phase pour les fréquences supérieures à 100 kHz. De plus, actuellement dans les laboratoires nationaux de métrologie, pour étalonner les shunts au-delà de 1 A les méthodes de mesure utilisées sont d’une part limitées en module à 100 kHz et en phase à 200 kHz et d’autre part elles donnent accès uniquement à un des deux paramètres : module ou phase de l’impédance du shunt. Ce travail de thèse a pour objectif d’étendre jusqu’à 10 A et 1 MHz les possibilités d’étalonnage des capteurs de forts courant et d’améliorer ainsi la traçabilité des mesures en courant alternatif. Nous avons dans un premier temps développé un shunt étalon de 10 A dont la réponse électromagnétique (jusqu’à 10 MHz) et la réponse thermique sont entièrement calculables : à 1 MHz le déphasage et l’écart de transposition sont respectivement de -0,01 mrad et 15 ppm. Dans un second temps, nous avons mis au point une méthode d'étalonnage traçable permettant de mesurer les shunts jusqu’à 10 MHz. La méthode de mesure, basée sur l'utilisation d'un analyseur de réseau vectoriel, permet de mesurer simultanément l’écart de transposition et la phase de l'impédance d'un shunt avec des incertitudes relatives inférieures à 1.10⁻³ à 1 MHz. / Measuring high alternating currents over a wide frequency bandwidth is essential for many applications including the monitoring of the electrical distribution network and the development of electric vehicles. In the first case, current measurement is necessary to quantify the quality of the grid in the presence of harmonics from intermittent renewable energies with a large frequency spectrum (several hundred kilohertz). In the second case, current measurement (up to several tens of amperes) is used to quantify the efficiency of an electric motor's traction chain: in current measurement, it is essential to take into account a large number of harmonics (up to 1 MHz) to ensure an accurate knowledge of the motor's efficiency. Resistors of low values, called "shunt", are then mandatory to measure high currents. Shunts are widely used as a resistance standard in metrology laboratories and precision instruments. Their use requires the preliminary knowledge of the following two parameters according to the frequency: Impedance phase shift; relative variation of the impedance magnitude according to its DC resistance value, this parameter is called “AC-DC difference”. For a current level of 10 A, the impedance of existing shunts shows strong variations in magnitude and phase for frequencies above 100 kHz. In addition, in National Metrology Institutes, to calibrate shunts beyond 1 A the measurement methods currently used are limited in magnitude up to 100 kHz and phase up to 200 kHz; and provide access to only one of the two parameters: magnitude or phase of impedance. The aim of this thesis is to extend the calibration capabilities of high current sensors up to 10 A and 1 MHz and thus improve the traceability of AC current measurements. Firstly, we developed a 10 A shunt standard whose electromagnetic (up to 10 MHz) and thermal responses are fully calculable: at 1 MHz the phase shift and transposition deviation are -0.01 mrad and 15 ppm respectively. Secondly, we developed a traceable calibration method to measure shunts up to 10 MHz. The measurement method, based on the use of a vector network analyzer, allows the AC-DC deviation and impedance phase of a shunt to be measured simultaneously with relative uncertainties less than 1.10⁻³ at 1 MHz.

A current meter has been designed, intended for surveillance of low-power battery driven devices with a large dynamic range in their current consumption. Among such devices may, for example, be nodes in a wireless sensor network (WSN). The large dynamic range originates in the nodes’ states from an active mode for data collection and communication to a sleep mode for preserving very limited energy and prolonging the lifetime of the device. The active mode draws current up to hundreds of milliamperes whilst the sleep mode’s current may be as low as 22 nA. This makes the dynamic range larger than 6 orders of magnitude. To perform measurements that prevail over noise sources and resolution of involved components, an increase in the SNR must be made. If the current is measured with a shunt resistor, this may be done by varying its resistance as required. The resistance should be as high as possible to maximize the SNR, but low enough such that the burden voltage of the current meter is kept within tolerances of the device. A literature study was done, and with the gained knowledge a circuit was designed and simulated in LTSpice. Then a printed circuit board (PCB) of the circuit was designed and implemented using Altium Designer (an ECAD program), manufactured and hand-soldered. The final PCB was tested but shown to have some design flaws that deteriorated the performance, for example too frequent switching of the current range.

No description available.

This thesis deals with the subject of fibre optic magnetic field sensors utilizing iron garnet materials. Such materials exhibit a large Faraday rotation which make them advantageous for application in compact mag­netic field sensors. After an introduction, in which fibre optic sensors and optical methods to measure electric current are reviewed, the original research work is summarized. A system for the measurement of the magneto-optic properties of trans­parent materials is described. Measurement results, showing the influence of temperature, magnetic field direction and sample treatment on the magneto-optical proper­ties of YIG-crystals, are presented. The proper­ties of thin magneto-optical waveguiding films have also been studied using different light coupling methods. Measurement results obtained for holo­graphic grating, prism and edge (end-fire) light coupling to different substituted YIG films are presented. It is shown that the launching method may affect the properties to be measured. The design and performance of several versions of extrinsic guided wave fibre optic magnetic field sensors are then reported. The sensors employ substi­tuted YIG (Yttrium Iron Garnet, Y3Fe5O12) thin film waveguides as sensing elements. Polari­zation maintaining fibres were used as feed and return to provide two signal channels. The signals were combined in a balanced measure­ment system, providing insensitivity to both fluctuations in optical power and loss. Sensors have been made both with separate fibres to guide the light to and from the sensing element and with a single fibre for both functions. The two fibre version, although less ”elegant”, is found to have a better performance. This version also makes it possible to determine both the magnitude and sign of the magnetic field. Measurement results indicate a usable measurement range of at least several mT with a noise equivalent magnetic field level of less than 8 nT/root(Hz). The design and performance of multimode fibre optic magnetic field sensors utilizing the Faraday effect in an epitaxially grown thick (YbTbBi)IG film is also described. This type of sensor is found to be linear over a range from 27 mT to less than 270 nT. Sensor prototypes suitable for current monitoring in high voltage transmission lines have also been developed. / QC 20111209 / YIG