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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Nabíječka lithiových akumulátorů / Li-ion accumulators charger

Vrba, Marek January 2012 (has links)
The main target of this thesis is to design and realize a prototype of a high capacity battery charger. The charger has been designed as a switching power supply based on a Flyback convertor with two transistors. As switching transistors the integrated circuit IR2110 has been selected. The convertor is controlled by a microcontroller board based on ATMega328 called Arduino Uno; some parts of the Arduino Uno Starter Kit are also used as LCD display, relay and button. In addition, an auxiliary source has been made; this one powers the integration circuit IR2110 and Arduino Uno board. Furthermore, this work introduces us to the processes of charging lithium batteries, types of lithium batteries and methods of charging the lithium iron phosphate (LiFePO4) battery.
152

Elektromagnetická kompatibilita spínaných napájecích zdrojů / EMC of switched-mode power supplies

Olivík, Lukáš January 2012 (has links)
The goal of this thesis is to design flyback converter with given parameters complying with standards for electromagnetic compatibility. This thesis describes detailed design of the flyback converter. It summarizes the recommendations for PCB design. Knowledge from number of comparative measurements of the impact of component selection on conducted emission signature was applied during the flyback converter design. Big part of the thesis is aimed on conducted emission measurement and separation of common mode and differential mode emissions. The simple and fast Time domain measurement of conducted emission is described. Final measurement of designed converter was performed at the end of the thesis.
153

Výstavba datových center / Data Center Development

Dóša, Vladimír January 2011 (has links)
This thesis presents and describes new global trends among build and operation of datacenters. Further it contains practical application of particular examples, and the theory is supplemented by new findings from given field.
154

Zvyšující měnič napětí / Step-up switched power source

Žamberský, Jan January 2016 (has links)
Práce se zabývá popisem jednotlivých typů zdrojů s důrazem na izolované topologie. Poté je rozebírána nejvhodnější volba pro zdroj na anodické bondování, kde jsou kladeny požadavky na vysoké výstupní napětí s malým proudem. Další část rozebírá problematická místa návrhu a na co je třeba dávat pozor. Poté je proveden vlastní návrh zdroje s popisem optimalizačních kroků. Tento zdroj je odsimulován. Dva rozdílné přístupy k realizaci takového zdroje jsou poté porovnány a nejlepší je vybrán. Je ukázána možnost, jak realizovat bipolární výstup. V poslední části je tento zroj sestaven a proměřeny jeho parametry.
155

Návrh napájecí části pro ADAHRS / Design of power supply for ADAHRS

Andrysík, Lukáš January 2016 (has links)
This master’s thesis contains basic description od ADAHRS system, DO-160 standard and mainly focuses on power supply desing with supercapacitors backup. It initialy deals with power supply requirements and continues with block diagram and multiple 5 V supply solutions. For selected 5 V supply it describes more deeply its properities and options. As the main theme it deals with providing power supply backup using supercapacitors – selecting particular method and configuring supercapacitor charging/discharging controller. It also includes tolerance and stress analysis of the components used in design. Lastly it describes testing of the final product.
156

Operation strategies of using energy storage for improving cost efficiency of wind farms. : Examining emergency power supply and support services.

Lundquist, Philip January 2021 (has links)
With the increase in the world energy demand and environmental incentives, renewable energy sources (RES) need to determine their place as some of the primary power sources in future power systems. However, due to uncertain energy production, renewable energy sources cause unbalance in the power system due to the unsynchronized supply and electricity demand. The intermittent power production causes undesired power fluctuation, affecting the power quality and reliability of the power source. Energy storage is one solution that is debated to increase the reliability of renewable energy production. This thesis aims to model and simulate hybrid energy storage system (HESS), constructed of hydrogen and ultracapacitor energy storage, to investigate different operation strategies for everyday use and crises. The two different energy storage technologies complement each other, where hydrogen fuel cells can produce power for long periods of time while the ultracapacitor can quickly maintain the balance of production and consumption of electricity for a short instance. The HESS showed promising results for emergency power supply and supported service operation strategies. In case of a power shortage, the HESS could cover for the disconnected production. The ultracapacitor proved to be a suitable component due to its ability to support the shortcomings of a hydrogen energy storage system. Moreover, the HESS could meet the requirements to deliver support services. However, further studies have to be done to investigate how the HESS can deliver multiple support services to increase profit and help maintain the power system's balance and security.
157

Toward Reliable, Secure, and Energy-Efficient Multi-Core System Design

Basu, Prabal 01 August 2019 (has links)
Computer hardware researchers have perennially focussed on improving the performance of computers while stipulating the energy consumption under a strict budget. While several innovations over the years have led to high performance and energy efficient computers, more challenges have also emerged as a fallout. For example, smaller transistor devices in modern multi-core systems are afflicted with several reliability and security concerns, which were inconceivable even a decade ago. Tackling these bottlenecks happens to negatively impact the power and performance of the computers. This dissertation explores novel techniques to gracefully solve some of the pressing challenges of the modern computer design. Specifically, the proposed techniques improve the reliability of on-chip communication fabric under a high power supply noise, increase the energy-efficiency of low-power graphics processing units, and demonstrate an unprecedented security loophole of the low-power computing paradigm through rigorous hardware-based experiments.
158

Die Elektrizitäts- und Gaswirtschaft im Spannungsfeld zwischen Wettbewerb und staatlicher Lenkung

Büdenbender, Ulrich 15 January 2008 (has links)
Die Entflechtung der Netze von den liberalisierten Bereichen der Energieversorgungsunternehmen (EVU) spiegelt sich in der Staatsaufsicht wider: Die liberalisierten Tätigkeitsbereiche werden dem freien Spiel der Kräfte ausgesetzt und unterliegen im Falle von Marktmacht der kartellrechtlichen Missbrauchsaufsicht. Demgegenüber wird der Netzbetrieb vollumfänglich und ausschließlich durch die Regulierungsbehörden überwacht. Trotz wesentlicher Unterschiede haben beide Formen der Staatsaufsicht die Funktion, unternehmerisches Handeln derart zu lenken, dass ein effektiver Wettbewerb im Energiemarkt möglich ist. Mit dem Ziel der Wettbewerbsförderung wird das Energierecht ständig Reformplänen unterzogen, ohne dass der Verordnungsgeber bereits bestehenden Konkretisierungsaufträgen umfassend nachkommen konnte. Unter Berücksichtigung der ausstehenden Rechtsverordnungen müssen Reformen ein angemessenes Verhältnis von staatlicher Steuerung und unternehmerischer Freiheit beachten. / Government supervision reflects the ongoing segregation of the distribution networks from the liberalised sectors of the power supply industry: The latter are exposed to full competition and are subject to the control of abusive practices by competition authorities. The networks, however, are controlled fully and exclusively by regulatory authorities. Despite their substantial differences, both forms of supervision are aimed at directing business activities to ensure effective competition on the energy markets. To promote competition, energy law is undergoing constant reform, but the required ordinances are yet to be enacted. New reform ideas should consider the outstanding ordinances and maintain an appropriate balance between government supervision and corporate freedom.
159

Elektrisk konstlast till modulator / Electric Load for Modulator

Smit, Marc Nathaniel January 2019 (has links)
ScandiNova Systems AB är ett företag som utvecklar och producerar pulsmodulatorer. Till deras senastutvecklade modulator vill ScandiNova ha en elektrisk konstlast för att testa den, innan den levereras. Just denna modulator kommer att ingå i en cancerbehandlingsmaskin hos kunden. I detta arbete tas det tillsammans med ScandiNova fram en kravspecifikation på hur konstlasten ska vara. Därefter tas en konstruktion i CAD-programvaran Autodesk Inventor fram. Arbetet resulterade i en konstruktion som uppfyller de flesta kraven förutom att den blev för dyr. Konstlasten kommer trots det att tillverkas och ScandiNova har precis påbörjat en utveckling på en ny konstruktion. / ScandiNova Systems AB is a company that develops and produces pulse modulators. For their latest developed modulator, ScandiNova wants an electric load to test it before it is delivered. The customer will use this particular modulator as a part of a cancer treatment machine. While working with this project, together with ScandiNova, a requirement specification on how the art load should be is taken. Next, a design is embodied with the CAD software Autodesk Inventor. The work resulted in a construction that meets most of the requirements except that it became too expensive. The load will nevertheless be manufactured and ScandiNova has just started a development on a new design.
160

Combining Solar Energy and UPS Systems

Bengtsson, Tobias, Hult, Håkan January 2014 (has links)
Solar Power and Uninterruptible Power Supply (UPS) are two technologies that are growing rapidly. The demand for solar energy is mainly driven by the trend towards cheaper solar cells, making it economically profitable for a larger range of applications. However, solar power has yet to reach grid parity in many geographical areas, which makes ways to reduce the cost of solar power systems important. This thesis investigates the possibility and potential economic synergies of combining solar power with UPS systems, which have been previously researched only from a purely technical point of view. This thesis instead evaluates the hypothesis that a combined solar and UPS system might save additional costs compared to regular grid-tied systems, even in a stable power grid. The primary reason is that on-line UPS systems rectifies and inverts all electricity, which means that solar energy can be delivered to the DC part of the UPS system instead of an AC grid, avoiding the installation of additional inverters in the solar power system. The study is divided into three parts. The first part is a computer simulation using MATLAB, which has an explorative method and aims to simulate a combined system before experimenting physically with it. The second part consists of experiments on a physical prototype system based on basic UPS and solar power components. The third part is an economical assessment of investment costs and energy balances, comparing two separate systems (UPS and solar power separate) to one combined (UPS & solar power). The results from the prototype system show that adding solar power to an UPS system does not interfere with the UPS functionality in any major way, however for optimal performance some additional integration may be necessary. On the contrary, the additional power terminal that the solar panels constitute, can increase system performance during certain operational conditions. The result of the economic analysis shows that a combined system has potential for both a lower investment cost due to cheaper components and increased energy savings through lower conversion losses. The conclusion from the study is that a combined solar energy and UPS system is technically feasible. Furthermore, a combined system has clear economic advantages over two separate systems. This means that a combined system might be economically profitable even in situations where a separate system is not. / Solenergi och avbrottsfri kraftförsörjning (UPS) är två tekniker som växer snabbt. Efterfrågan på solenergi ökar huvudsakligen på grund av den snabba utvecklingen mot billigare solceller, vilket lett till att solenergi blivit lönsamt i en större mängd applikationer. I många områden är solenergi dock fortfarande inte kostnadsmässigt konkurrenskraftigt jämfört med traditionella energikällor, vilket gör en fortsatt sänkning av kostnaderna för solenergi till en viktig fråga för solenergiindustrin. Detta examensarbete har som syfte att undersöka om det är tekniskt möjligt att kombinera solenergi med UPS-system samt potentialen för ekonomiska synergier med denna kombination. Tidigare forskning inom området har endast undersökt denna kombination från en rent teknisk synvinkel. Detta examensarbete driver istället hypotesen att ett kombinerat solenergi- och UPS-system kan leda till större kostnadsbesparingar jämfört med ett traditionellt nätanslutet solenergisystem, även i ett stabilt elnät som i Sverige. En on-line UPS skyddar en känslig last genom att kontinuerligt likrikta och sedan åter växelrikta inkommande ström för att därmed både isolera lasten från nätet samt höja strömkvalitén. I UPS-systemet finns därmed en likströmsdel dit solpanelerna direkt kan kopplas istället för att skicka den genererade solenergin ut på elnätet. Därmed undviks inköp och installation av sol-växelriktare i solenergisystemet. Studien är uppdelad i tre delar. Första delen är en datorsimulering i MATLAB och syftar till att explorativt undersöka det kombinerade systemet för en optimerad design innan fysiska experiment utförs. Den andra delen av studien utgörs av experiment på ett fysiskt prototypsystem baserat på ett principiellt UPS- och solenergisystem. Den tredje delen av studien är en ekonomisk analys av både investeringskostnader och energibalanser som jämför ett kombinerat system (UPS & sol) med två separata system (UPS & sol separat). Resultaten från prototypsystemet visar att påkopplandet av solceller i en principiell UPS har mycket låg påverkan på UPS-systemets funktionalitet, samt att solcellerna som en extra energikälla under vissa driftförhållanden kan ha en positiv påverkan på UPS-systemet. För optimal prestanda kan dock en viss integration av systemen krävas.  Resultatet från den ekonomiska analysen visar att ett kombinerat system har potential att sänka investeringskostnaden genom billigare komponenter. Ett kombinerat system kan även leda till en högre energibesparing jämfört med ett nätanslutet solenergisystem eftersom konverteringsförlusterna i UPS-systemet sjunker i det kombinerade systemet. Slutsatsen av studierna är att ett kombinerat solenergi- och UPS-system är tekniskt möjligt. Dessutom finns betydande ekonomiska synergier med ett kombinerat system. Detta innebär att ett kombinerat system kan vara lönsamt även i fall där ett separat solelsystem inte är det.

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