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This research proposes a method for estimating the residual capacity of Li-ion batteries. The charging and discharging characteristics of Li-ion batteries are investigated and analyzed by a battery test system. The measurement of the initial capacity is based on the improved open-circuit voltage measurement, which compensates the effects of battery aging and self-discharging. The measurement of the used capacity is based on the improved coulomb counting measurement, which compensates the effects of output current and environmental temperature. The designed system provides various functions for battery charging and discharging, battery voltage measuring and recording, battery capacity estimation and calculation, and the log files can be used for further battery characteristics analysis.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19185号 / 工博第4062号 / 新制||工||1627(附属図書館) / 32177 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 木村 健二, 教授 立花 明知 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The underground power cable failures introduce challenges to the reliability of underground residential distribution networks. Smart Grid initiatives have interest to improve equipment reliability. Asset management of several utilities are interested towards online cable insulation condition monitoring and health index evaluation. This dissertation demonstrates a new technique for online condition assessment of power cable insulation condition based on capacitor switching transient voltage measurements. While majority of utilities in USA are following corrective maintenance for MV cables, only few utilities have procedures in place for offline preventive maintenance of MV cables. The technique demonstrated in this research will enable all utilities to carry out preventive online monitoring of MV power cables. This dissertation also demonstrates that capacitive test point of cable elbow connector can be used to measure switching transients for power cables in service. This technique can be easily incorporated into existing capacitive test points of cable accessories. This technique has a potential to develop and deploy measurement units for online monitoring of power cables.

Orientador: Walmir de Freitas Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-23T18:19:46Z (GMT). No. of bitstreams: 1 Trindade_FernandaCasenoLima_D.pdf: 1722766 bytes, checksum: dec87e1e3e98a246135a42def8eef876 (MD5) Previous issue date: 2013 / Resumo: Atualmente, cargas de diversos tipos de consumidores têm se tornado cada vez mais sensíveis a variações e interrupções de energia. Na maioria das vezes, falhas no fornecimento de energia são resultados da ocorrência de defeitos (faltas) em sistemas de distribuição de energia elétrica. Estes defeitos prejudicam a confiabilidade do fornecimento de energia e podem resultar em afundamento de tensão, interrupções momentâneas ou sustentadas e em elevados custos operacionais. Em vista disto, cada vez mais, os consumidores estão conscientes sobre o assunto e observa-se a necessidade da elaboração de soluções eficientes para melhorar os índices de confiabilidade e de qualidade do fornecimento de energia elétrica. Um dos métodos mais eficazes para melhorar os índices de confiabilidade e qualidade de energia elétrica em sistemas de distribuição consiste no desenvolvimento de técnicas rápidas e precisas de localização de defeitos na rede. Embora os métodos de localização de defeito empregados em alimentadores de distribuição ainda sejam rudimentares, a integração de técnicas de medição, comunicação, do conhecimento da configuração da rede e atuação de religadores em tempo real, além de dados provenientes dos Sistemas de Informações Geográficas em sistemas de distribuição permite o desenvolvimento de métodos mais eficientes, que exploram informações provenientes de diferentes locais da rede (informações distribuídas) e não apenas da subestação. Neste contexto, este trabalho explora métodos de localização de defeitos baseados em medidas de tensão provenientes de diferentes locais de modernos sistemas de distribuição. Três métodos foram investigados: (1) o primeiro, baseado na correspondência de valores de tensão, utiliza os parâmetros elétricos da rede e duas ou mais medidas de tensão ao longo do alimentador; (2) o segundo método, baseado na correspondência da corrente de falta, utiliza os parâmetros elétricos da rede e uma quantidade maior de medidas de tensão que o primeiro método; (3) finalmente, o terceiro método, baseado no mapeamento das zonas de tensão reduzida, não necessita do conhecimento completo dos parâmetros da rede, no entanto, é necessário utilizar uma maior quantidade de medidores que nos outros dois métodos. Os resultados dos testes realizados mostram que de acordo com a disponibilidade de medição de tensão ao longo do alimentador, um destes métodos pode ser escolhido para localizar o defeito de maneira eficaz / Abstract: Nowadays, loads from different classes of customers have become more sensitive to variations and interruptions from power supply. Frequently, failures in electrical energy delivery are caused by occurrences of faults in distribution systems. Such faults decrease the reliability of power delivery, increase operational costs and may result in power quality problems, such as voltage sag, short or long term outages. Since the customers consciousness is increasing, the need of efficient solutions to improve reliability and power quality indices is also increasing. One of the most efficient approaches to improve such indices in distribution systems is to develop fast and accurate fault location techniques for aerial feeders. Even though fault location methods dedicated to distribution feeders are still rudimentary, the recent integration of measurement, communication, real time knowledge of feeder configuration and reclosers trip and Geographic System Information allows the development of more efficient solutions, which explores information from different places from the grid (distributed information) and not only from the substation. In this context, this work explores fault location methods based on voltage measurements applied to modern distribution systems. Three methods were investigated: (1) the first one is based on matching voltage values, this method requires the network electrical parameters and two or more voltage meters installed along the feeder; (2) the second method is based on the correspondence of fault current, this method uses the network electrical parameters and a higher quantity of meters than the first method; (3) finally, the third method is based on the identification of low voltage zones, this method does not require network electrical parameters, however it needs a higher quantity of voltage meters than the other two methods. The test results show that according to the voltage measurement availability along the feeder, one of these methods can be chosen to efficiently locate the fault / Doutorado / Energia Eletrica / Doutora em Engenharia Elétrica

Currently organic-inorganic hybrid perovskite solar cells (PSCs) is one kind of promising photovoltaic technology due to low production cost, easy fabrication method and high power conversion efficiency. Charge transport layers are found to be critical for device performance and stability. A traditional electron transport layer (ETL), such as TiO2 (Titanium dioxide), is not very efficient for charge extraction at the interface. Compared with TiO2, SnO2 (Tin (IV) Oxide) possesses several advantages such as higher mobility and better energy level alignment. In addition, PSCs with planar structure can be processed at lower temperature compared to PSCs with other structures. In this thesis, planar-structure perovskite solar cells with SnO2 as the electron transport layer are fabricated. The one-step spin-coating method is employed for the fabrication. Several issues are studied such as annealing the samples in ambient air or glovebox, different concentration of solution used for the samples, the impact of using filter for solutions on samples. Finally, a reproducible fabrication procedure for planer-structure perovskite solar cells with an average power conversion efficiency of 16.8%, and a maximum power conversion efficiency of 18.1% is provided.

In the high voltage grid, voltage measurements are made in dedicated voltage-transformers. These devices are expensive and insulation failures could impact directly on the system, and even cause a power outage. A non-contact measurement technique, on the other hand, does not require a connection to the conductors, and the sensors can therefore be much cheaper by avoiding the need for high voltage insulation. A capacitive coupling between three measurement electrodes, close to ground, and a high voltage three phase conductor system is used to model and measure the electric field and thereby determine the potentials of the conductors. A 2D-model is used for simulations, where the sensors are modeled as ideal, the conductors are modeled in an infinite wire approximation, and the ground plane is approximated as a perfect conductor. For non-ideal sensors a transfer function from the potentials on the measurement equipment to the potentials on the conductors is derived as a lumped-circuit model. The L2-norm errors for the amplitude and the phase in the reconstructed signals are calculated and measured for various sensor distances. Simulations show that the sensor distance should not be larger than the conductor distance to mitigate the erroneous effects from distance uncertainties. The optimal sensor distance depends on the quota between the height from the sensors to the conductors and the conductor distance. Measurements show, in accordance with the theory, that the sensor distance should not be larger than the conductor distance. To reduce the amplitude and phase shift errors the sensors should be placed close to the ground. For applied load resistances there is a tradeoff between amplitude- and phase shift errors. Additionally, higher load resistances attenuate higher frequencies. Measurements have verified that this technique is capable of detecting high harmonics and transients. The relatively low cost and the movability makes this method highly applicable for quick diagnostics on many locations in a grid, where the data can be evaluated on-site using computer based scripts. / I kraftnät utförs idag högspänningsmätningar av spänningstransformatorer. Dessa är dyra, och isolationsproblem  kan ha en direkt effekt på kraftnätet, och till och med skapa strömavbrott. En beröringsfri mätmetod, å andra sidan, kräver ingen direkt koppling mellan mätutrustningen och ledarna. Sensorerna kan därmed bli billigare eftersom de inte behöver högspänningsisoleras. En kapacitiv koppling mellan tre stycken mätelektroder, placerade nära jordplanet, och ett högspänt trefasledarsystem  används för att modellera och mäta det elektriska fältet och därigenom bestämma ledarnas potentialer. En 2D-modell används för simuleringar, där sensorerna modelleras som ideala, ledarna modelleras enligt en raktrådsapproximation (oändligt långa raka ledare), och jordplanet approximeras vara en perfekt ledare med oändlig utsträckning. För icke-ideala sensorer härleds en överföringsfunktion från den uppmätta potentialen på mätutrustningen till ledarnas potentialer som en analog kretsmodell. L2-norm-felen för amplitudfel och fasfel för de rekonstruerade signalerna beräknas och mäts för olika sensoravstånd. Simuleringar visar att sensoravståndet inte bör vara större än ledaravståndet för att dämpa felinverkande effekter från osäkerheter i avståndsuppskattningar. Det optimala sensoravståndet beror på kvoten mellan höjden från sensorerna till ledarna och ledaravståndet. Mätningar visar, i enlighet med teorin, att sensoravståndet inte bör vara större än ledaravståndet. För att reducera amplitud- och fasfel bör sensorerna placeras nära jordplanet. För påkopplade lastresistanser gäller att det är en byteshandel mellan amplitud- och fasfel. För övrigt gäller att högre lastresistanser dämpar högre frekvenser. Mätningar verifierar att denna teknik är kapabel att detektera höga frekvenser och transienter. Den relativt låga kostnaden och metodens rörlighet gör att den kan appliceras för snabbdiagnostik på många punkter i ett kraftnät, där det insamlade datat kan utvärderas på plats med hjälp av datorbaserade skript.

We report the experimental observation of hysteresis-free negative capacitance (NC) in thin ferroelectric Hf₀.₅Zr₀.₅O₂ (HZO) films through high-speed pulsed charge-voltage measurements. Hysteretic switching is suppressed by the addition of thin Al₂O₃ layers on top of the HZO to prevent the screening of the polarization. We observe an S-shaped polarization-electric field dependence without hysteresis in agreement with Landau theory, which enables direct extraction of NC modeling parameters for ferroelectric HZO. Hysteresis-free NC is demonstrated down to 100 ns pulse widths limited only by our measurement setup. These results give critical insights into the physics of ferroelectric NC and practical NC device design using ferroelectric HZO.

Logic-in-memory circuits promise to overcome the von-Neumann bottleneck, which constitutes one of the limiting factors to data throughput and power consumption of electronic devices. In the following we present four-input logic gates based on only two ferroelectric FETs (FeFETs) with hafnium oxide as the ferroelectric material. By utilizing two complementary inputs, a XOR and a XNOR gate are created. The use of only two FeFETs results in a compact and nonvolatile design. This realization, moreover, directly couples the memory and logic function of the FeFET. The feasibility of the proposed structures is revealed by electrical measurements of HKMG FeFET memory arrays manufactured in 28nm technology.

The subject of graduation thesis is a design of line analyser according to standard EN61000-4-30 class A. The analyser is determine to be used for quality control of supplied electric power which is, during electric power transmission, affected by several disturbances. Power line analyser should measure single-phase and three-phase network parameters in LV and HV systems. Measured parameters can be shown on the full colour TFT display, stored in the device memory or sent to other devices such as PC. For communication between the device and PC the USB, Ethernet or RS485 interface are used.