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1
Giske, Gustav, and Mikael Hug. "Linear Ferrite Generator Prototype for Wave Power." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228744.
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A linear, direct drive, scale model prototype generator has been designed at KTH Royal Institute of technology in Sweden. The prototype is based on a scaled down electromagnetic optimization made by researcher Anders Hagnestål. The aim of the project is to verify the calculations experimentally and by using ferrite magnets, there is an opportunity to develop a competitively priced and environmentally friendly generator for wave power plants. Based on the electromagnetic optimization a mechanical design has been developed using computer aided design (CAD). Structural calculations have been made to ensure that the design withstands the large magnetic forces involved. Furthermore, different techniques and challenges appearing in the build of the prototype have been evaluated and explained. A description of the advantages of the design and the basic electromagnetic design is also included. The build is underway and is expected to be finished during 2018.En linjär direktdriven generatorprototyp har designats på KTH, Kungliga Tekniska högskolan i Sverige. Prototypen är baserad på en nerskalad elektromagnetisk optimering gjord av Anders Hagnestål. Målet med projektet är att verifiera beräkningar experimentellt och genom att använda ferritmagneter finns det en möjlighet att utveckla en konkurrenskraftig och miljövänligare generator för vågkraftverk. Baserat på den elektromagnetiska optimeringen har en mekanisk design tagits fram med hjälp av datorstödd design (CAD). Hållfasthetsberäkningar har gjorts för att säkerställa att designen klarar av de stora magnetiska krafter den utsätts för. Vidare har även olika tekniker och utmaningar som uppstått i byggnationen utvärderats och beskrivits. En beskrivning av designens fördelar och den grundläggande elektromagnetiska designen har även inkluderats. Byggnationen pågår och beräknas vara färdig under 2018.
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Hug, Mikael, and Gustav Giske. "Linear Ferrite Generator Prototype for Wave Power." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-239384.
Full textAbstract:
A linear, direct drive, scale model prototype generator has been designed at KTH Royal Institute of technology in Sweden. The prototype is based on a scaled down electromagnetic optimization made by researcher Anders Hagnestål. The aim of the project is to verify the calculations experimentally and by using ferrite magnets, there is an opportunity to develop a competitively priced and environmentally friendly generator for wave power plants. Based on the electromagnetic optimization a mechanical design has been developed using computer aided design (CAD). Structural calculations have been made to ensure that the design withstands the large magnetic forces involved. Furthermore, different techniques and challenges appearing in the build of the prototype have been evaluated and explained. A description of the advantages of the design and the basic electromagnetic design is also included. The build is underway and is expected to be finished during 2018.
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Danielsson, Oskar. "Wave Energy Conversion : Linear Synchronous Permanent Magnet Generator." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7194.
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Simone, Dominic J. "Modeling a linear generator for energy harvesting applications." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/44669.
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Approved for public release; distribution is unlimitedThe intent of this research is to draw attention to linear generators and their potential uses. A flexible model of a linear generator created in MATLAB Simulink is presented. The model is a three-phase, 12-pole, non-salient, synchronous permanent magnet linear generator with a non-sinusoidal back electromotive force (EMF) but could easily be adapted to fit any number of poles or any back EMF waveform. The emerging technologies related to linear generators such as wave energy converters and free-piston engines are explained. A selection of these technologies is generically modeled and their results are discussed and contrasted against one another. The model clearly demonstrates the challenges of using linear generators in different scenarios. It also proves itself a useful tool in analyzing and improving the performance of linear generators under a variety of circumstances.
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DEL, GUSTO LUIGI CARMINE. "Linear Rational Insurance Model & Economic Scenario Generator." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/285067.
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Linear Rational Insurance Model
Abstract
The aim of the first work is to provide a closed pricing formula for insurance contracts in a linear rational framework, which consists in assuming the existence of a linear drift diffusion process and a state price density which is a linear function of it.
The main advantage of this process is that we can compute the conditional expectation of polyno- mials function of this diffusion: in fact a polynomial can be see as a linear combination of an enlarged set of variables with a linear drift, this can be proofed by means of the Itô’s formula.
This result is very important because it allows us, under the hypothesis that the diffusion part is a martingale, to use all the results we have about linear drift diffusions for this new set of variables.
As a consequence, we are able to give the price of three important life insurance contracts: the sur- vival and death benefit and the guaranteed annuity option (also called GAO).
It is about the GAO that we can see the advantage of the framework we are using: actually the payoff of the GAO is not an affine or a polynomial function, so the only way to treat it is by performing a change of measure or a Monte Carlo simulation. We show that, under the assumption that the state space is compact, we are able to approximate the GAO payoff by a polynomial, which will allow us to find a closed formula for the price of this contract.
The end of this work is dedicated to some numerical experiments which have the aim to point out the importance of the choice of the degree of the approximated polynomials in order to have reliable results. We show that a ten degree polynomial is able to estimate with a small error the Monte Carlo price of the GAO.
This work extend the existing literature concerning polynomial models and their application in life insurance, proposing a pricing method also for liabilities which are not necessarily building blocks, but more complicated functions, like the guaranteed annuity option.
Economic Scenario Generator
The aim of this second work is to build an economic scenario generator with the intention of improving the portfolio allocation of Bpifrance.
In order to do that, we have to pass through a different number of steps.
The first thing is to study, by a principal component analysis, the present portfolio of Bpifrance, in order to find the variables which explains the most of its variability.
A second step consists in selecting from the market the financial instruments that allows us to replicate the components we retained from the step before. This part is then completed by both an univariate and multivariate analysis of these assets, finding in this way the stylized facts that we need to take into account when choosing a model for the diffusion of the price of these financial factors.
The third step, and last concerning our work, is to estimate the parameters of the models we retained and see if they are able to fit the empirical data and, as a consequence, if they could be used as a part of our future economic scenario generator.
In order to achieve this point, we focus only on the diffusion of the equity indices, proposing also a model who takes into account the dependency on the inflation. We will see that on the basis of our data there is no evidence to link the return on equity indices on the realisations of this macroeconomic factor.Linear Rational Insurance Model Abstract The aim of the first work is to provide a closed pricing formula for insurance contracts in a linear rational framework, which consists in assuming the existence of a linear drift diffusion process and a state price density which is a linear function of it. The main advantage of this process is that we can compute the conditional expectation of polyno- mials function of this diffusion: in fact a polynomial can be see as a linear combination of an enlarged set of variables with a linear drift, this can be proofed by means of the Itô’s formula. This result is very important because it allows us, under the hypothesis that the diffusion part is a martingale, to use all the results we have about linear drift diffusions for this new set of variables. As a consequence, we are able to give the price of three important life insurance contracts: the sur- vival and death benefit and the guaranteed annuity option (also called GAO). It is about the GAO that we can see the advantage of the framework we are using: actually the payoff of the GAO is not an affine or a polynomial function, so the only way to treat it is by performing a change of measure or a Monte Carlo simulation. We show that, under the assumption that the state space is compact, we are able to approximate the GAO payoff by a polynomial, which will allow us to find a closed formula for the price of this contract. The end of this work is dedicated to some numerical experiments which have the aim to point out the importance of the choice of the degree of the approximated polynomials in order to have reliable results. We show that a ten degree polynomial is able to estimate with a small error the Monte Carlo price of the GAO. This work extend the existing literature concerning polynomial models and their application in life insurance, proposing a pricing method also for liabilities which are not necessarily building blocks, but more complicated functions, like the guaranteed annuity option. Economic Scenario Generator The aim of this second work is to build an economic scenario generator with the intention of improving the portfolio allocation of Bpifrance. In order to do that, we have to pass through a different number of steps. The first thing is to study, by a principal component analysis, the present portfolio of Bpifrance, in order to find the variables which explains the most of its variability. A second step consists in selecting from the market the financial instruments that allows us to replicate the components we retained from the step before. This part is then completed by both an univariate and multivariate analysis of these assets, finding in this way the stylized facts that we need to take into account when choosing a model for the diffusion of the price of these financial factors. The third step, and last concerning our work, is to estimate the parameters of the models we retained and see if they are able to fit the empirical data and, as a consequence, if they could be used as a part of our future economic scenario generator. In order to achieve this point, we focus only on the diffusion of the equity indices, proposing also a model who takes into account the dependency on the inflation. We will see that on the basis of our data there is no evidence to link the return on equity indices on the realisations of this macroeconomic factor.
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Hamood, Ahmed Mohammed. "Two-stage thermoacoustic electricity generator with push-pull linear alternator." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15681/.
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This study focuses on the design, construction and experimental evaluation of a thermoacoustic electricity generator prototype with a push-pull linear alternator. The push-pull coupling offers a solution to run the looped-tube thermoacoustic engine at high acoustic impedance using one alternator. The novel configuration of the engine consists of two identical half-wavelength stages with an alternator connected between them. A simulation was carried out using the DeltaEC programme. The modelling started by investigating the required acoustic field for the alternator. The engine modelling has been done as half of the engine which is one-stage, because the DeltaEC shooting method showed that it was unable to run two identical stages. The engine is 16.02 m long and run at 55.1 Hz. The simulation showed that it is possible to produce more than 133 W of electricity at a thermal-to-electric efficiency of 23% while using helium pressurized at 28 bar. In practice, the engine failed to self-start. After exciting it to run by an external pulse, an electric power of 48.6 W was generated with a thermal-to-electric efficiency of 2.7%. The high heat leak detected was reduced by installing an insulating gasket between the ambient heat exchanger and regenerator holder, which encouraged the electricity generation to increase. The engine became self-starting when the regenerator thickness was reduced from 73 mm to 71.8 mm. The maximum generated electric power was 73.3 W at 3.33% thermal-to-electric efficiency at a heating power of 2200 W, and a maximum efficiency of 3.6% was achieved at 71.9 W electric power at a heating power of 2000 W. The success of the two-stage engine with a push-pull linear alternator encouraged modelling and design of a four-stage engine with two push-pull linear alternators able to generate up to 269 W of electricity, theoretically.
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Barajas, Solano José Ignacio. "Novel active magnetic bearings for direct drive C-Gen linear generator." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28900.
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This document presents a novel active magnetic levitation system. In the pursued of this endeavour different topics related with wave energy were explore. Climate change and energy security are the main motivation to pursued new options for non-fossil fuels energy generation. An overview of renewable energy and specifically of wave energy was presented. The potential for wave energy in The United Kingdom turn out to be 75 TWh/year from wave energy, 3 times more of what wind energy has produced in 2013. This means a massive impact on the energy market and emission reduction. In order to achieve this, improvements on wave energy devices have to be done. An overview of wave energy converters was covered selecting the C-Gen as the generator topology this document will base its studies. Linear generator bearings are desired to have long lifespan with long maintenance intervals. The objective is to come with an active magnetic levitation design that can replace traditional bearings augmenting the reliability of the system. Therefore magnetic bearings option have been reviewed and simulation experimentations has resulted in a novel active magnetic levitation system using an air-cored coils Halbach array acting over a levitation track. The configuration would generate bi directional repulsion forces with respect of the levitating body. Different software were used to analyse the magnetic field and forces generation. Additionally a prototype was built and tested to corroborate the results. As part of the modelling a mathematical model was explored and robust control implementation was also realised. Finally a scalability study of the device as well as a reliability analysis was done. Although the reliability studies shows an increase of ten times of the mean time to failure, the concept is not able to endure the loads acting on the generator unless the magnetic bearings became bigger than the generator and therefore economically unfeasible.
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Karlsson, Joakim, and Ola Söderström. "Review of Magnetic Materials Along With a Study of the Magnetic Stability and Solidity of Y40." Thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-176021.
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Wave energy converters (WECs) are relatively new power sources under rapiddevelopment. WECs utilize permanent magnets to generate power and theperformance of these magnets have a great impact on the produced effects in theWECs. This paper is primarily constructed to investigate the magnetic and mechanicalproperties of a specific kind of permanent magnets, referred to as Y40. The paperalso gives a comprehensive review of magnetic materials in general, slightly focusingon magnetic stability. Literature studies has been made to get an understanding ofhow the Y40 magnets will perform under external influences such as reversed field,temperature change and mechanical stress. Further, a compression test has beenmade to examine the Y40s solidity. From the results of the tests and from theinformation provided in literature it is considered to be little to no risk for the Y40sto lose magnetization due to external influences. However, because of theirassembled structure, the Y40 magnets are very likely to break in their joints duringpressure lower than what is expected in the WECs.
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Oladeinde, Abiola Omobolaji. "Linear demultiple solution based on bottom-multiple generator (BMG) approximation: subsalt example." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4407.
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Significant quantities of hydrocarbons are found in complex salt environments.
One of the modern challenges of exploration and production activities is to image below
salt. This challenge arises from the complexities of salt structures, weak primaries from
the subsalt, and the interference of free-surface multiples with the weak primaries of the
subsalt. To effectively process subsalt data, we need to develop a method of attenuating
free-surface multiples that preserves the amplitude and phase of primaries and does not
introduce artifacts at either near and far offsets. In this thesis, we will demonstrate that
the weak primaries of the subsalt can be preserved while attenuating free-surface
multiples. The method used for the demonstration is the bottom-multiple generator
(BMG) reflector approximation. This technique requires that a portion of the data
containing only primaries be defined. A multidimensional convolution of the data
containing only primaries with the actual data will predict free-surface multiples and
hence is used to attenuate free-surface multiples from the actual data. This method is one
of the most effective methods for attenuating free-surface multiples; however, the method requires muting data at the BMG location. One of the issues investigated in this
thesis, is to establish the sensitivity of the BMG demultiple technique when the mute at
the BMG location end up cutting some seismic reflections, which can be the case in
complex environments such as the Gulf of Mexico and Gulf of Guinea, where freesurface
multiples interfere with primaries. For this investigation, we generated synthetic
data through the 2D elastic finite-difference modeling technique. The synthetic seismic
data contain primaries; free-surface multiples, and internal multiples, and direct waves
acquired over a 2D geological model that depicts a shallow-water geology.
In this thesis, we also investigate if the first step of the BMG demultiple
technique can sufficiently attenuate free-surface multiples. For this investigation, we
designed a 2D geological model, which depicts the deep offshore environment, and we
generated synthetic data through the 2D elastic finite-difference modeling technique.
After performing the various investigations mentioned above, the following
conclusions were made, that the demultiple result is not affected when the mute at the
BMG location end up cutting some primaries, that the first step of the BMG demultiple
technique is not sufficient for the demultiple, and that the weak subsalt primaries are
preserved during demultiple processes. We compared shot gathers and zero offset data
before and after the demultiple.
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Amine, Ramdani Ahmed, and Sebastian Rudnik. "Design and Construction of High Current Winding for a Transverse Flux Linear Generator Intended for Wave Power Generation." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240366.
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There is currently a high demand for electric power from renewablesources. One source that remains relatively untapped is the motionof ocean waves. Anders Hagnestål has been developing a uniquelyefficient and simplified design for a point-absorb buoy generator byconverting its linear motion directly into alternating electric power usinga linear PM engine. To test this method, a smaller prototype isbuilt. Its characteristics present some unusual challenges in the designand construction of its winding.Devices of this type typically use relatively low voltage (690V typicallyfor a wind turbine, compared to the 10kV range of traditionalpower plants). To achieve high power, they need high current, whichin turn requires splitting the conductors in the winding into isolatedparallel strands to avoid losses due to eddy currents and current crowding.However, new losses from circulating currents can then arise. Inorder to reduce said losses, the parallel conductors should be transposedin such a way that the aggregate electromotive force the circuitsthat each pair of them forms is minimized.This research and prototyping was performed in absence of advancedindustrial means of construction, with limited space, budget,materials, manpower, know-how, and technology. Manual ingenuityand empirical experimentation were required to find a practical implementationfor: laying the cables, fixing them in place, transferringthem to the machine, stripping their coating at the ends and establishinga reliable connection to the current source.Using theoretical derivations and FEM simulation, a sufficientlygood transposition scheme is proposed for the specific machine thatthe winding is built for. A bobbin replicating the shape of the enginecore is built to lay down the strands.The parallel strands are then organized each into their respectivebobbin, with a bobbin rack and conductor funneling device being designedand constructed to gather them together into a strictly-organizedbundle. An adhesive is found to set the cables in place.Problems with maintaining the orientation and configuration of thecables in the face of repeated torsion are met and solved. A chemicalsolution is used to strip the ends of the conductors, and a reliableconnection is established by crimping the conductors into a bi-metalCu-Al lug.ivIn conclusion, the ideal transposition schemes required to cancelout circulating currents due to magnetic flux leakage are impossibleto put in practice without appropriate technological means. The feasibletransposition scheme turns out to be a simple mirroring of conductors’positions, implemented by building each half of the windingseparately around replicas of the core and then connecting them usingcrimping lugs.Efterfrågan på el från förnybara källor är hög och inget tyder på att det kommer ändras den närmsta tiden. En källa till förnybar el som än idag står relativt orörd är den där man använder energin från havsvå- gor. Det är denna förnybara källa Anders Hagnestål haft i åtanke när han nu bygger en unikt effektiv generator med syftet att i ett senare skede utvinna el med hjälp av flytande punktabsorberande vågkraft- system. Generatorn är av den linjära typen och omvandlar det punk- tabsorberande systemet rörelse till el. För att testa denna generator- modell så påbörjades bygget av två fullskaliga prototyper 2017. Denna uppsats behandlar specifikt arbetet med generatorlindningen till pro- totyperna och innefattar processen från design till själva byggnatio- nen. Lindingen består av flertalet mindre och isolerade lindningsleda- re med uppgift att bland annat minska skinneffekt och virvelströms- förluster. När man använder denna metod så uppkommer dock ett nytt problem vilket härstammar från att lindningsledarna är samman- kopplade i vardera ända och bildar på så sätt n slutna strömkretsar. Konsekvensen kan vara stora förluster från cirkulerande strömmar på grund av det magnetiska ströflöde som finns runt järnkärnan som lindningen omsluter. Utgångspunkten för att minimera dessa cirkule- rande strömmar är att transponera alla lindningsledare på ett sätt så att den resulterande elektromotoriska spänningen för varje strömkrets blir så liten som möjligt. Med hjälp av förenklade modeller samt FEM simuleringar så bestämdes ett lämpligt sätt att transponera lindningstrådarna utifrån oli- ka kriterier. Lösningen blev att lindningstrådarna endast transponera- des en gång med en så kallad 180 grader transponering. Detta ger en tillräckligt god minimering av de cirkulerande ström- marna, men den stora fördelen med denna lösning är att det är möjligt att linda maskinen med de små resurser projektet hade tillgång till, dock var detta till en stor nackdel då väldigt mycket tid gick till att hitta egna tillvägagångsätt för att utföra byggandet av lindningen på ibland okonventionella sätt.
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Pluim, Jonathon Douglas. "DESIGN OF A HIGH FIDELITY WAKE SIMULATOR FOR RESEARCH USING LINEAR CASCADES." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244039010.
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Aravinthan, Abhiramy. "Linear quadratic regulator design for doubly fed induction generator using singular perturbation techniques." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5523.
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Doubly fed induction generators (DFIG) are widely used in wind power generation because of their ability to be operated at varying rotational speeds while producing power output at a constant frequency. Electrical dynamics of a DFIG is modeled using field oriented control and represented as fourth order system. This fourth order dynamics exposes a two-time scale behavior. Using singular perturbation techniques the time scales can be separated as slow and fast subsystems. Feedback control schemes can be designed and the closed-loop stability of each model can be compared. In this work, a linear quadratic feedback controller is designed for the DFIG electrical dynamics using exact, reduced order and composite models. The performances of the closed loop models are compared based on the system cost. The robustness and reliability of the control schemes are analyzed for each controller designs based on the nominal system. Based on the analysis and results, the reduced order controller performance is equally as good as the exact and composite designs during steady state operations.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Schutte, Jacques. "Optimisation of a transverse flux linear PM generator using 3D Finite Element Analysis." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17930.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Several transverse flux and longitudinal flux linear generator topologies exist for freepiston Stirling engine applications. In this thesis the transverse flux permanent magnet linear generators are investigated together with a back-to-back converter which can deliver the electrical energy from the linear generator to the electrical network. The transverse flux permanent magnet linear generator is geometrically optimised with the aim to maximise the power-to-weight ratio while maintaining preset power and efficiency levels. An optimised 3 kW linear generator is built and the measured results correlate to the simulation results. A close-loop current control scheme is introduced to control the current of the rectifier, which is part of the back to back converter. The transverse flux permanent magnet linear generator is connected to the input of the rectifier which has the ability to force a specific current from the generator. The measured results of the rectifier correlate to the results of the simulations that were done. The current control present some complications and it is suggested that another control scheme is used. A close-loop voltage control scheme is introduced for the control of the DC bus voltage. The DC bus is connected between the rectifier and the inverter, which is the other part of the back-to-back converter. A close-loop current control scheme is introduced to control the inverter current that flows from the inverter to the electrical network. The measured results of the inverter and the DC bus correlate to the results of the simulations that were done. The results of the system, including the generator, rectifier and inverter, tested as a unit is presented and discussed.
AFRIKAANSE OPSOMMING: Verskeie tranverse vloed en longitudinale vloed lineˆere generator topologie¨e bestaan vir vrysuier Stirling enjin toepassings. In hierdie tesis word ’n transverse vloed permanente magneet lineˆere generator ondersoek saam met ’n omsetter. Die omsetter dra die elektriese energie van die generator oor aan die elektriese netwerk. Die transverse vloed permanente magneet lineˆere generator word geometries geoptimeer met die doel om die drywing-tot-gewig verhouding te maksimiseer terwyl vasgestelde drywing en effektiwiteit vlakke behou word. ’n Geoptimeerde 3kW lineˆere generator prototipe is vervaardig en die gemete resultate is geverifieer met die simulasie resultate. ’n Geslote lus stroombeheer strategie word voorgestel om die stroom te beheer van die gelykrigter, wat deel is van die omsetter. Die transverse vloed permanente magneet lineˆere generator word aan die gelykrigter, wat die vermo¨e het om ’n spesifieke stroom uit die generator te forseer, se intree verbind. Die gemete resultate van die gelykrigter wat gebou is stem goed ooreen met die van die simulasies wat gedoen is. Die stroombeheer hou komplikasies in wat bespreek word. Dus word die gebruik van ’n alternatiewe stroombeheer voorgestel. ’n Geslote lus spannings beheer strategie¨e word voorgestel om die gs. busspanning te beheer. Die gs. bus is gekonnekteer tussen die gelykrigter en die wisselrigter, wat ook deel uitmaak van die omsetter. ’n Geslote lus stroom beheer word voorgestel om die stroom te beheer wat vanaf die wisselrigter na die elektriese netwerk toe vloei. Die gemete resultate van die wisselrigter en die gs. bus stem goed ooreen met die van die simulasies wat gedoen is. Die resultate van die hele stelsel, wat die generator, gelykrigter en die wisselrigter insluit, wat as ’n eenheid getoets is word weergegee en bespreek.
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Shek, Jonathan K. H. "Reaction force control of a linear electrical generator for direct drive wave energy conversion." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/14404.
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Joubert, Louis Hoogenhout. "Design optimisation of a transverse flux linear oscillating generator for resonant free-piston Stirling applications." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96849.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: The design optimisation of a linear oscillatory electric generator for application in freepiston Stirling engines is described in this thesis. A basic overview of free-piston Stirling engine technology is given by firstly providing a brief description of the operation of the heat engine. The applications of free-piston Stirling engines in industry are given and the proposed future applications are described. Different types of electrical machine designs from industry and academia are evaluated in a literature study. A classification structure is also proposed based on the magnetic flux variation within the designs. Based on the literature study, a transverse flux, single-phase, moving magnet, tubular topology was chosen for investigation. Athree dimensional finite element simulation was chosen as the most appropriatemethod to model the linear electrical machine. A commercial simulation package was called from a simulation script and the outputs from the finite element simulation were again used to calculate the electrical machine performance parameters using the instantaneous voltageand current values. A sequential quadratic programming algorithm was used to perform optimisation of the machine topologies, with the optimisation variables being dimensional parameters that describe the machine geometry and the goal of the optimisation to minimise the active mass of the machine, while maintaining preset minima for the output power and the efficiency. The machine was optimised for a number of different translator configurations and the different configurations were analysed and compared. It was found that a quasi-Halbach arrangement of the permanent magnets yielded the lowest overall active mass. A comparative study is also presented, where this quasi-Halbach variant is compared to a commercial machine. It was found that the linear machine design with a quasi-Halbach arrangement compares well with the commercial machine. A prototype and test bed was designed and constructed. Due to manufacuring difficulties however, the machine could not be completed in time for testing.
AFRIKAANSE OPSOMMING: Die ontwerpsoptimering van ’n lineêre ossillerende elektriese generator vir toepassing in vrysuier Stirling enjins word beskryf in hierdie tesis. ’n Basiese oorsig van vrysuier Stirling enjin tegnologie word gegee deur eerstens ’n kort beskrywing te gee van die werking van die hitte-enjin. Die aanwending van vrysuier Stirling enjins in industrie word gegee en voorgestelde toekomstige toepassings word beskryf. Verskillende tipes elektriese masjien ontwerpe vanuit die industrie en die akademie word geëvalueer in ’n literatuurstudie. ’n Klassifiseringstruktuur, gebaseer op die magnetiese vloedverandering in die ontwerpe, word ook voorgestel. ’n Transverse vloed, enkelfase, bewegende magneet, tubulêre topologie is gekies vir die ondersoek, gebaseer op die onder andere die literatuurstudie. ’n Drie-dimensionele eindige element simulasie is gekies as die mees geskikte metode om die lineêre elektriese masjien te modelleer. ’n Kommersiële simulasie pakket is deur middel van ’n simulasie skrip geroep en die uitsette vanaf die eindige element simulasie is weer gebruik om die werksverrigtingsparameters van die elektriese masjien te bereken deur gebruik te maak van die oomblikswaardes van die spanning en stroom. ’n Sekwensiële kwadratiese programmering algoritme is gebruik om optimering van die masjien topologieë te doen, met die dimensionele parameters wat die masjien geometrie beskryf as die optimeringsveranderlikes en doel van die optimering om die aktiewe massa van die masjien te minimeer, terwyl die uitsetdrywing en die benuttingsgraad by voorafgestelde minima gehou word. Die masjien is geoptimeer vir verskeie translator konfigurasies en die verskillende konfigurasies is geanaliseer en vergelyk. Dit is bevind dat ’n kwasi-Halbach skikking van die permanente magnete die laagste totale aktiewe massa gelewer het. ’n Vergelykende studie is ook aangebied, waar die kwasi-Halbach variant vergelyk is met ’n kommersiële masjien. Dit is bevind dat die lineêre masjien met die kwasi-Halbach skikking baie goed vergelyk met die kommersiële masjien. ’n Prototiepe masjien en toetsopstelling is ontwerp en aan mekaar gesit. Maar as gevolg van vervaardigbaarheids tekortkominge kon toetse op die prototiepe nie betyds gedoen word nie.
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Caraher, Sarah. "Bearing options, including design and testing, for direct drive linear generators in wave energy converters." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5740.
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The key focus of this research was to investigate the bearing options most suited to operation in a novel direct drive linear generator. This was done through bearing comparisons, modelling and testing. It is fundamental that the linear generator is designed to suit the marine environment. Key design constraints include reliability, survivability, maintenance intervals and cost. Resilient mechanical structural components, such as bearings, will prolong the time a device can operate without maintenance hence prolonging the operating period. Effective lifespan predictions for bearings will feed into the structural design of the generator which forms part of an overall objective to combine each generator design stage into one integrated design process. This promises to provide a cost effective, light weight generator design. This thesis covers the initial investigations into effective, long life and low-wear bearings to meet the operating demands of WEC. It includes an assessment of conventional bearing technology, designs of water-fed hydrostatic bearings and testing of novel polymer bearings. The development of an experimental test rig from a prototype linear generator is described. The rig was built in order to validate and fully explore the potential of self-lubricating, submersible polymer bearings with the ultimate aim of identifying wear constants and frictional properties of the bearings in the low-speed, mid to high-load, oscillating operation of a WEC in order to more accurately predict a bearing lifespan. The outcome of this research served to underpin the need for the design of application specific bearing systems to be based on empirically determined data and observations from test data taken from application specific tests. For inclusion in the design of these linear generators, sizing a bearing requires knowledge of the electrical loading in addition to the expected operating conditions of a WEC. Choosing bearing materials and hence lubricant regimes is dependant on the thermal operating characteristics. Then bearing knowledge in terms of size, load capacity and lifespan can be put directly into the structural model. This iterative process of design can then be merged into a fully integrated generator design tool hence this research was part of the development of an integrated design tool for direct drive generators.
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Baiense, Jr Joao C. "Vortex Generator Jet Flow Control in Highly Loaded Compressors." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/916.
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"A flow control method for minimizing losses in a highly loaded compressor blade was analyzed. Passive and active flow control experiments with vortex generator jets were conducted on a seven blade linear compressor cascade to demonstrate the potential application of passive flow control on a highly loaded blade. Passive flow control vortex generator jets use the pressure distribution generated by air flow over the blade profile to drive jets from the pressure side to the suction side. Active flow control was analyzed by pressuring the blade plenum with an auxiliary compressor unit. Active flow control decreased profile losses by approximately 37 % while passive flow control had negligible impact on the profile loss of a highly loaded blade. Passive flow control was able to achieve a jet velocity ratio, jet velocity to upstream velocity, of 0.525. The success of active flow control with a velocity ratio of 0.9 suggests there is potential for passive flow control to be effective. The research presented in this thesis is motivated by the potential savings in the applications of passive flow control in gas turbine axial compressors by increasing the aerodynamic load of each stage. Increased stage loading that is properly controlled can reduce the number of stages required to achieve the desired pressure compression ratio."
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Li, Bin. "Reaction force control implementation of a linear generator in irregular waves for a wave power system." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7862.
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Most designs for wave energy converters include a hydraulic (or pneumatic) interface between the wave device and the generator to smooth electricity production, but a direct drive power take-off system is a possible way of increasing the power transfer efficiency and the reliability, which was first adopted by Archimedes Wave Swing. Direct drive wave energy systems normally include a low speed linear generator directly coupled with the wave device. With no mechanical interface, the mechanical energy loss and maintenance requirements can, in theory, be significantly reduced. To maximize the energy capture, the motion of the wave energy converter must be controlled to achieve mechanical resonance so that the velocity is in phase with the incoming waves. So far, a number of control methods have been proposed, but few of them have been tested experimentally. For direct drive linear generators in real sea conditions, reaction force control is shown to be an effective way to achieve control where knowledge of future wave could not be required. Different reaction force control methodologies are suggested where the force is provided directly from the linear generator. Among these methodologies, complex conjugate control is regarded as the optimal control and can be used to achieve mechanical resonance. When resonance occurs, some system parameters such as the system excursion and required power take-off force become extremely large, and may exceed the design parameters. In this thesis, the system is modelled under reaction force control taking into account practical considerations which are based on design parameters. A novel control scheme for a direct drive linear generator to achieve such reaction force control in irregular waves is proposed, where a voltage-source rectifier is employed as the bridge between the linear generator and the dc bus. The application of linear generator in real wave conditions not only has inherent advantages, but also present a big challenge for controller design in order to obtain maximum power production. For a linear generator in real sea states, reaction force control idea can be implemented to adjust the velocity of motion, hence to maximize the power production, where the required currents in the generator coils to provide the desired force are constantly varying in frequency and amplitude. The control strategy of the active rectifier is developed based on the derived three-phase currents and the dynamic response of the system to determine varying modulation indices. The unknown situations and some unmeasurable parameters in the system degrade the performance of the control system, hence the current feedback and PI controller are both adopted to reject the effect of the disturbance. Simulation verifications are included for the proposed control idea.
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Xiaoyu, Dang, Zhang Yong, and Zhou Tingxian. "A METHOD TO ENHANCE THE BIT RATE OF LINEAR CODE GENERATOR IN SPREAD-SPECTRUM COMMUNICATION SYSTEM." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/607337.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaBecause of the limits of feedback devices, high-speed pseudo-noise code generators cannot depend simply on the improvement of clock rate. Based on the characteristic equation of linear feedback registers and the m-sequence sampling theory as well, deduction is made to indicate a novel way to improve the speed of pseudo-noise code generators 2^l (2^l < n, n is the length of registers) times as fast as the conventional one. Also, we extend our applications to non-reducible and non-primitive polynomials. It could be a good way to generate these linear codes at higher rates.
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Seo, UnJae [Verfasser]. "Permanent Magnet Linear Generator for the Application as Range Extender in Full Electric Vehicles / UnJae Seo." Aachen : Shaker, 2018. http://d-nb.info/1159835810/34.
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Lee, Hyung-Woo. "Advanced control for power density maximization of the brushless DC generator." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1587.
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This dissertation proposes a novel control technique for power density maximization of the brushless DC (BLDC) generator which is a nonsinusoidal power supply system. In a generator of given rating, the weight and size of the system affect the fuel consumption directly, therefore power density is one of the most important issues in a stand-alone generator. Conventional rectification methods cannot achieve the maximum power possible because of a distorted or unsuitable current waveform. The optimal current waveform for maximizing power density and minimizing machine size and weight in a nonsinusoidal power supply system has been proposed theoretically and verified by simulation and experimental work. Also, various attributes of practical interest are analyzed and simulated to investigate the impact on real systems.
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Dall'Ora, Luca. "Analysis and Design of a Linear Tubular Electric Machine for Free-piston Stirling Micro-cogeneration Systems." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423541.
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The UE investments for the renewable source development, in order to achieve the set goals (Kyoto protocol and “20-20-20” targets), push to investigate in new technologies and to develop the existing. In this context, the cogeneration (CHP) plays a fundamental role, and in particular, the micro-CHP has wide development margins.
Among the different cogeneration process, the systems driven by a free-piston Stirling engine are one of the most significant challenges in the research area. In such systems, the thermal energy, coming from primary energy source (for example renewable energy), is converted into mechanical energy through a Stirling engine, and then a linear generator converts the mechanical energy into electrical energy, finally, the generator is connected to the electric grid or to the load by means of an electric converter. The use of the linear generator, instead of the traditional systems of linear to alternating motion conversion (rod-crank system), allows achieving several advantages, including: improving the system reliability, noise and cost reduction. Finally, this kind of system, if well-designed, allows improving the system efficiency.
In this thesis a linear generator, directly coupled to a free-piston Stirling engine in a CHP system, was developed and analysed. It was found, after a first phase of the study and literature review, that the most convenient choice, from the technical and economic point of view, is a single-phase tubular permanent magnet linear generator. In particular, the magnets are made of plasto-neodymium, while, for the realization of the stator magnetic circuit, due to the geometrical complexity, soft magnetic composites (SMC) materials have been considered.
In order to determine the generator performance, an analysis method based on FEAs was developed. This simplified method (HFEA) allows the study and the comparison of different magnetization patterns and current supply strategies. The proposed methodology exploits the representation of the magnetization spatial harmonics through an analytical processing that allows taking into account different magnetization profile of the permanent magnets. Thus, it was possible to reconstruct the most important quantities, such as the flux density and the flux linkage, superposing the effect of each harmonic obtained through the Fourier analysis. Furthermore, a procedure, able to reproduce the effects of magnetic saturation of the mover, generally not negligible in such kind of machines, was developed. For this purpose, an appropriate surface current distribution on the yoke of the mover was introduced, in order to reproduce the demagnetizing effect due to the saturation.
By means of the air gap flux density, the force provided by linear generator was calculated, while, by means of the flux density sampled on suitable points on the stator and mover yokes, the iron losses were estimated and then the machine efficiency. By means of the flux linkage the emf provided by linear generator was determined.
The results show a very good agreement with corresponding FEAs. The proposed analysis method allows carrying out a parametric analysis with a lower computational effort. Thanks to this feature, different magnetization patterns, supply strategies and SMC materials can be compared in order to optimize the machine design.
A prototype based on the design guidelines was built; then, a procedure based on experimental measurement was developed to characterize the electromagnetic parameters. To determine the magnetization profile of the magnets, the flux density on the mover surface was carried out by means of a Gaussmeter. As regards the SMC materials that compose the stator core, a calculation method was developed from suitable experimental elaborations, in order to determine the most important magnetic properties, such as the BH curve and core loss coefficients.
From experimental results, it can be noted that the actual characteristics are poorer than those provided by the manufactured datasheets, likely due to the manufacturing processes and spurious air gaps between the SMC modules. The update electromagnetic parameters are used to determine the actual performance of the machine, particularly to estimate the efficiency, the emf and the force.
Finally, a simplified model of the cogeneration system was developed in order to predict the dynamic behaviour and particularly, the actual values of the speed, output power and efficiency. This model allows developing the control strategy of the linear generator acting on the electric converter.Gli investimenti da parte dei paesi della UE per lo sviluppo delle fonti rinnovabili, al fine di raggiungere gli obiettivi preposti (Protocollo di Kioto e Piano “20-20-20”), spingono a ricercare nuove tecnologie e a sviluppare quelle già esistenti. In questo ambito, la cogenerazione ricopre un ruolo fondamentale, ed in particolare, la micro-cogenerazione, anche in ambito domestico, presenta ancora ampi margini di sviluppo. Tra le diverse modalità di cogenerazione, i sistemi free-piston azionati da motori Stirling rappresentano una tra le sfide più importanti nell’ambito della ricerca. In tali sistemi l’energia termica, proveniente da una fonte di energia primaria (ad esempio di tipo rinnovabile), è convertita in energia meccanica attraverso un motore Stirling; successivamente un generatore lineare converte l’energia meccanica in elettrica; ed infine, un convertitore elettrico interfaccia il generatore con un carico o con la rete elettrica. L’utilizzo del generatore lineare, al posto dei tradizionali sistemi di conversione del moto da lineare ad alternato (sistema biella-manovella), consente di ottenere diversi benefici, tra cui: migliorare l’affidabilità del sistema, limitare il rumore e ridurre i costi. Infine, questo sistema, se ben progettato, permette di aumentare il rendimento dell’impianto di cogenerazione. In questo lavoro di tesi è stato progettato ed analizzato un generatore lineare da accoppiare direttamente ad un motore Stirling free-piston in un sistema di cogenerazione domestico. Dopo una prima fase di studio e ricerca bibliografica, è stato riscontrato che la scelta più conveniente dal punto di vista tecnico-economico, risulta essere quella di un generatore monofase tubolare a magneti permanenti. In particolare, i magneti sono a base di plasto-neodimio, mentre, per la realizzazione del circuito magnetico di statore, data la complessità geometrica, si sono considerati materiali magnetici compositi (SMC). Al fine di determinare le prestazioni del generatore, è stata sviluppata una metodologia di analisi, basata su analisi FEM, che permettesse lo studio ed il confronto di diverse tipologie di magnetizzazione, in particolare radiale e Halbach, e considerare diverse strategie di alimentazione. Tale metodologia (HFEA) sfrutta la rappresentazione delle armoniche spaziali di magnetizzazione attraverso un'elaborazione di tipo analitico che permette di riprodurre diverse funzioni di magnetizzazione dei magneti permanenti. In tal modo, è stato possibile ricostruire le principali grandezze di interesse (induzione e flusso concatenato) sovrapponendo l’effetto di ciascuna armonica ricavata attraverso l'analisi di Fourier. Inoltre, è stata sviluppata una procedura in grado di riprodurre gli effetti della saturazione magnetica del traslatore, generalmente non trascurabile in questo tipo di macchine. A questo proposito sono state introdotte opportune distribuzioni superficiali di corrente sul giogo del traslatore che riproducono l'effetto smagnetizzante dovuto alla saturazione. Dai valori dell’induzione al traferro, è possibile risalire al valore della forza esplicata dal generatore; mentre, dai valori dell’induzione, campionati in opportuni punti all’interno dei nuclei magnetici dello statore e del traslatore, è stato possibile stimare le perdite nel ferro e quindi il rendimento della macchina. Dal profilo del flusso concatenato è stato possibile stimare l’andamento della forza elettromotrice generata. I risultati hanno evidenziato un ottimo accordo con le corrispondenti analisi agli elementi finiti, con il vantaggio rispetto a queste di poter effettuare analisi parametriche che coinvolgono diverse grandezze progettuali con tempi di calcolo inferiori. Grazie a questa caratteristica, è stato possibile confrontare le prestazioni con varie tipologie di magnetizzazioni, strategie di alimentazione e caratteristiche di materiali SMC, effettuando una prima ottimizzazione del progetto della macchina. Dopo aver realizzato un prototipo sulla base delle indicazioni progettuali, è stata sviluppata una procedura sperimentale atta a determinare i parametri elettromagnetici del generatore, per verificarne la congruenza con le ipotesi progettuali e mettere a punto quindi i modelli per le analisi successive. Per determinare il profilo di magnetizzazione dei magneti sono state effettuate delle misure di induzione sulla superficie del materiale magnetico mediante l’uso di un Gaussmetro. Invece, per i materiali SCM che costituiscono lo statore della macchina, a partire da opportune elaborazioni sperimentali, è stato sviluppato un metodo di calcolo in grado di determinare le principali proprietà magnetiche (permeabilità, caratteristica BH e coefficienti delle perdite nel ferro per isteresi, correnti parassite ed eccesso). Dai risultati sperimentali si nota che le caratteristiche reali sono meno performanti rispetto a quelle fornite dai datasheet dei costruttori, molto probabilmente a causa dei processi di lavorazione e dei traferri spuri presenti tra i moduli di SMC. I valori delle grandezze magnetiche aggiornate sono stati utilizzati per stimare le reali condizioni di esercizio della macchina, in particolare per determinare il valore del rendimento, della tensione e della forza sviluppata dalla macchina. È poi stato sviluppato un modello semplificato che consente di riprodurre il comportamento dinamico del sistema di cogenerazione completo e di ricavare il profilo effettivo di velocità, la potenza erogata e il rendimento complessivo del sistema. Considerando l'interazione tra i singoli componenti, l'applicazione di questo modello risulta di estrema importanza per eseguire l’analisi e permette di mettere a punto la strategia di controllo del generatore agendo sul convertitore di interfacciamento con il carico.
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Vermaak, Rieghard. "Development of a novel air-cored permanent magnet linear generator for direct drive ocean wave energy converters." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80267.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: In hierdie tesis word ’n nuwe lug kern permanent magnet (PM) lineêre generator (LG) vir toepassing tot direk aangedrewe (DA) oseaan golf energie omsetters (GEO) ontwikkel. Die nuwe LG word ontwikkel vanaf die lineêre dubbel-kant topologie in ’n poging om probleme met die huidige longitudinale vloed (LV) yster kern LGs, wat tot dusvêr oorheersend voorkom in eksperimentele DA-GEOs, te oorkom. Die grootste probleem met hierdie LGs is die masiewe aantrekkings kragte tussen hul yster stators en die PM transleerders. ’n Groot hoeveelheid strukturuele staal word benodig om die luggaping te handhaaf, terwyl die las op die laars ook ’n groot probleem is. Die nuwe LG gebruik ’n lug kern stator wat alle aantrekkings kragte tussen die stator en transleerder elimineer en dus die nodige strukturuele material verminder. Die topologie van die transleerder is ook van so ’n aard dat die netto aantrekkings kragte op enige spesifieke PM ideaal nul is; dit verminder die strukturuele materiaal selfs verder. Die transleerder het ook ’n nuwe transversale vloed pad wat die sogenaamde paarwyse vloed koppeling wat in LV-LGs voorkom, en die negatiewe effekte daarvan, verhoed. ’n Aantal nuwe bydraes tot die veld van LGs vir DA-GEO word in hierdie tesis gemaak. ’n Nuwe topologie lug kern PMLG is ontwikkel soos bespreek. Dit sluit in die ontwikkeling van analitiese en eindige element modelle en ’n optimerings prosedure wat vinnig optimale dimensies vir minimum aktiewe massa van die nuwe LG vind. In die ontwerp word dit ook gevind dat die drywingsdigtheid van LGs verbeter kan word deur zero oorvleuling tussen die die stator en transleerder by die slag endte toe te laat. ’n 1 kW prototipe van die nuwe LG word ontwerp en gebou; die uitvoerbaarheid van die konstruksie vir die nuwe topologie op ’n klein skaal word dus gedemonstreer. ’n Unieke toets opstelling word ook ontwerp en is gebasseer op bestaande toerusting in die vorm van ’n wind turbine generator en rug-aan-rug spannings bron omsetters. Met die toets opstelling word ’n enkel frekwensie golf ge-emuleer om die teorie en simulasies te verifieer en word ook ’n voorspellende beheer strategie geimplementeer, wat vir die eerste keer gedemonstreer word vir LGs vir DA-GEOs. Goeie ooreenstemming tussen die gemete en gesimuleerde data bevestig die voorgestelde modellerings en ontwerps metodes.
AFRIKAANSE OPSOMMING: In this thesis, a novel air-cored permanent magnet (PM) linear generator (LG) is developed with application to direct drive (DD) wave energy converters (WECs). The novel LG is developed from the linear double-sided topology in an attempt to overcome the problems with current longitudinal flux (LF) iron-cored LGs, which have so far been dominant in experimental DD-WECs. The biggest problem with these LGs is the massive attraction forces between their iron stators and PM translators. A large amount of structural steel is required to maintain the air gap, while the load on the bearings is also a large concern. The novel LG uses an air-cored stator which eliminates any attraction forces between the stator and translator and hence reduces the required structural material. Furthermore, the topology of the translator is such that the net attraction force on any particular PM is ideally zero, which even further reduces the structural material required for the translator. A new transverse circulating flux path is also introduced in the translator which prevents pair-wise flux coupling and its negative effects as observed in LF-LGs. A number of new contributions are made to the field of LGs for DD-WECs in this thesis. A novel topology aircored PMLG is developed as described. This includes the development of analytical and finite element models and an exhaustive optimisation procedure for quickly finding optimal dimensions for minimum active mass of the novel LG. In the design it is also found that the power density of LGs can be improved by allowing zero overlap between the stator and translator at the stroke ends. A 1 kW prototype of the novel LG is designed and built; the feasibility of constructing the novel LG on a small scale is as such demonstrated. A unique test rig is designed based on existing equipment in the form of a wind turbine generator and back-to-back voltage source converters. The test rig allows emulation of a monochromatic wave for verifying the theory and simulations and also allows for implementation of a predictive control strategy, which is for the first time demonstrated for LGs for DD-WECs. Good agreement between measured and simulated data confirms the presented modelling and design methods.
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Guldbrandzén, Erling, and Manthan Shah. "Mechanical design of transverse flux linear generator for wave power : Mekanisk konstruktion av linjär transversalflödesgenerator för vågkraft." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190166.
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En transversalflödesgeneratortopologi skall användas för att generera elektricitet av havsvågor. Den huvudsakliga fördelen med detta koncept är dess låga förluster och att en högre kraftdensitet kan uppnås vid låga hastigheter. Med den relativt långsamma hastigheten hos vågor har detta maskinkoncept potentialen att vara väsentligt effektivare än vanliga permanentmagnetiserade synkrongeneratorer, om systemet är direktdrivet, det vill säga om det inte behövs någon växellåda. Denna avhandling behandlar de mekaniska aspekterna av generatorn där det kontrollerades huruvida en mekaniskt hållbar konstruktion för att generera elektricitet från energin i vågorna kan skapas till en låg kostnad.Dimensionerna på utskjutande delar på järnstackarna är viktiga eftersom de påverkar den totala effektiviteten av systemet. Ett antal olika kombinationer testades för att kontrollera spänningarna och den totala elastiska deformationen av delen. Dessa värden jämfördes med analytiska beräkningar. Maximal deformation kontrollerades för stator och translator med finita elementmetoden (FEM) och kontrollerades analytiskt med balkteori och var inom acceptabla värden.Termisk expansion av de mekaniska delarna i generatorn kontrollerades och var tillräckligt låga. Lim 3M DP270 och vinylester föreslogs för dess egenskaper. Vinylester är planerad att testas ytterligare på olika delar av statorn och translatorn.Infästning av lagren med hjälp av VKR på statorn har föreslagits för ytterligare utvärdering.En form på det isolerande materialet har föreslagits till translatorn. Ett koncept för att klämma ihop både stator och translatordelar togs fram och koncept för både stator och translator har simulerats med FEM och utvärderats ytterligare med hjälp av analytiska beräkningar.Linjära styrbanor har föreslagits för den linjära rörelsen av translatorn.Ett koncept för att fästa statorn och translatorn har föreslagits i avhandlingen. En CAD-modell har utvecklats för ytterligare utvärdering av delar.The Transverse flux generator type topology is to be used to generate electricity for wave energy purposes. The main advantage of using this concept is low losses and higher values of force density can be achieved at low speeds. With the relatively slow speed of the waves this machine outperforms the standard permanent magnet synchronous machines. This thesis is related to the mechanical aspects of the generator where it was checked whether a mechanically sustainable structure could be created at a low cost to generate electricity from the energy of the waves. Maximum deformation was checked for the stator and translator using finite element method (FEM) and analytically checked by beam theory and was within the acceptable range. Thermal expansion of the mechanical parts in the generator is sufficiently low. Adhesives 3M DP270 and vinyl ester were suggested for their properties. Vinyl ester is planned to be further tested on different parts of stator and translator.Attachment of the bearings using HFRHS on the stator has been suggested for further evaluation. A shape of insulating material has been suggested for the translator. The dimensions on the protrusions of the iron stacks are important since they affect the overall efficiency of the system. A number of different combinations were tried to check the stress values and total deformation in the part. The results were further evaluated and most appropriate combination was selected. A clamping concept was devised for both the stator and translator parts and concepts for both the stator and translator have been simulated by FEM tools and other aspects have been evaluated using analytical calculations.Guideways have been suggested for the linear motion of the translator. A concept to attach the stator and the translator is also suggested in the thesis. A CAD model has been developed for further evaluation of parts.
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Jalal, Aslan Sabahaldeen. "Design and performance investigation of flux-concentrated tubular linear generator for an external combustion free piston engine." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/4007.
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The increasing global desire for highly fuel efficient power systems and the need for environmentally friendly energy sources is driving much present research in electrical power. A linear power system, where a linear machine is driven directly by a free piston engine, offers scalability and a wide range applicability. Standalone power units, hybridised power systems and range extenders in electrified vehicles are all potential applications for this technology. This thesis explores the application of a Linear Joule Engine driving a Permanent Magnet Linear Machine for electrical power generation. Whereas most Joule cycle engines have a rotary compressor and expander, at smaller scale this configuration suffers from leakage around the blades. The linear engine uses a double acting free piston configuration running on the external combustion Joule-cycle, overcoming the low efficiency inherent in small scale gas turbines. The key element for electrical power generation, and the main focus of this thesis, is the development of a linear machine operating as a generator, the design of which is heavily constrained by the geometrical and the operational characteristics of the engine. Using specific constraints for an 5kW engine and by using two dimensional finite element analysis, a novel design methodology of tubular PM linear machine with modular armature winding and feasible arrangements of magnets on the translator member is outlined. The effect of core material, pole number and power conversion system on the machine design are investigated, highlighting the effect of the interconnected design variables on the resulting performance and material use, all satisfying design objectives. A Flux – Concentrated PM configuration is selected for further development. vi In order to accomplish an overall system performance investigation tool, at first the development of a general novel linear machine model is introduced and tested in a feedforward manner with accounts for all machine interacting electromagnetic forces. Then, a novel dynamic model incorporating both the linear machine model driven by the linear Joule engine model, coupled together in a closed loop form, is realized. The coupled model bridges mechanical and electrical parts of the engine-generator, and provides a solid dynamic performance prediction of the system focusing on identifying the effect of cogging force on system performance and the resultant electrical power loss and electrical efficiency. Compared with the reported cogging force reduction techniques, a novel structural technique and a selection criteria are presented with two dimensional axisymmetric finite element analysis verification showing the effectiveness of the proposed technique. Finally, a machine prototype of the selected design model is manufactured and tested on a bespoke test rig to validate the design model findings. Manufacturing recommendations and future achievable steps are reported for future development of the existing work.
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Burchell, Joseph William. "Advancement of direct drive generator systems for offshore renewable energy production." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33263.
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As machine topologies and technologies mature, the fundamental function of the device is honed. Direct drive machines have the potential to launch the renewable energy sector into a new era of large scale, reliable, offshore power generation. With advancements in new technologies, such as superconductivity, the reduction of generator mass due to incorporation of machine and device structures, the continued advancements in component and system reliability; direct drive generators have the ability to outsize geared wind systems and simplify submerged linear and rotary power generation. The research held within this thesis will focus on improving direct drive power take off systems for offshore renewable energy power generation by splitting the area into four parts. The first part will discuss the various methods of energy extraction within the offshore and marine environment. The future of the sector will be discussed, and a forecast of technological advancement and existing reliability issues will be provided based on current data. The second part will focus on drive trains and direct drive generators, assessing the current topologies and suggesting alternatives that may thrive in a variety of large and small offshore renewable machines. The third part investigates the application of novel linear bearings in direct drive systems for offshore and submerged operation. A brief study of the loads found in wave applications will be presented and the testing of several polymer bearing materials will be outlined. The final part will discuss the potential benefits of flooding the airgap of a direct drive generator with sea water for marine applications. Results will be presented from two linear test rigs and the marinisation of devices will conclude the report.
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Nessler, Chase A. "Characterization of Internal Wake Generator at Low Reynolds Number with a Linear Cascade of Low Pressure Turbine Blades." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1270749309.
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Hong, Yue. "Numerical Modelling and Mechanical Studies on a Point Absorber Type Wave Energy Converter." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305650.
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Oceans cover two thirds of the Earth’s surface and the energy potential of ocean waves as a renewable energy source is huge. It would therefore be a tremendous achievement if the vast mechanical energy in waves was converted into a form of energy that could be used successfully by society. For years, scientists and engineers have endeavored to exploit this renewable energy by inventing various generators designed to transform wave energy into electrical energy. Generally, this sort of generator is called a Wave Energy Converter (WEC). In this thesis, the research is based on the WEC developed in the Lysekil Project. The Lysekil Project is led by a research group at Uppsala University and has a test site located on the west coast of Sweden. The project started in 2002. So far, more than ten prototypes of the WEC have been deployed and relevant experiments have been carried out at the test site. The WEC developed at Uppsala University can be categorized as a point absorber. It consists of a direct-drive linear generator connected to a floating buoy. The linear generator is deployed on the seabed and driven by a floating buoy to extract wave energy. The absorbed energy is converted to electricity and transmitted to a measuring station on land. The work presented in this thesis focuses on building a linear generator model which is able to predict the performance of the Lysekil WEC. Studies are also carried out on the damping behavior of the WEC under the impact of different sea climates. The purpose is to optimize the energy absorption with a specific optimal damping coefficient. The obtained results indicate an optimal damping for the Lysekil WEC which can be used for optimizing the damping control. Additionally, the impact two central engineering design features (the translator weight and the stroke length) are investigated. The aim is to find a reasonable structural design for the generator which balances the cost and the energy production.
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Kamf, Tobias. "Automated Production Technologies and Measurement Systems for Ferrite Magnetized Linear Generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330866.
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The interest in breaking the historical dependence on fossil energy and begin moving towards more renewable energy sources is rising worldwide. This is largely due to uncertainties in the future supply of fossil fuels and the rising concerns about humanity’s role in the currently ongoing climate changes. One renewable energy source is ocean waves and Uppsala University has since the early 2000s been performing active research in this area. The Uppsala wave energy concept is centered on developing linear generators coupled to point absorbing buoys, with the generator situated on the seabed and connected to the buoy on the sea surface via a steel wire. The motion of the buoy then transfers energy to the generator, where it is converted into electricity and sent to shore for delivery into the electrical grid. This thesis will mainly focus on the development and evaluation of technologies used to automate the manufacturing of the translator, a central part of the linear generator, using industrial robotics. The translator is a 3 m high and 0.8 m wide three sided structure with an aluminum pipe at its center. The structure consists of alternating layers of steel plates (pole-shoes) and ferrite magnets, with a total of 72 layers per side. To perform experiments on translator assembly and production, a robot cell (centered on an IRB6650S industrial robot) complimented with relevant tools, equipment and security measures, has been designed and constructed. The mounting of the pole-shoes on the central pipe, using the industrial robot, proved to be the most challenging task to solve. However, by implementing a precise work-piece orientation calibration system, combined with selective compliance robot tools, the task could be performed with mounting speeds of up to 50 mm/s. Although progress has been made, much work still remains before fully automated translator assembly is a reality. A secondary topic of this thesis is the development of stand-alone measurement systems to be used in the linear generator, once it has been deployed on the seabed. The main requirements of such a measurement system is robustness, resistance to electrical noise, and power efficiency. If possible the system should also be portable and easy to use. This was solved by developing a custom measurement circuit, based on industry standard 4–20 mA current signals, combined with a portable submersible logging unit. The latest iteration of the system is small enough to be deployed and retrieved by one person, and can collect data for 10 weeks before running out of batteries. Future work in this area should focus on increasing the usability of the system. The third and final topic of this thesis is a short discussion of an engineering approach to kinetic energy storage, in the form of high-speed composite flywheels, and the design of two different prototypes of such flywheels. Both designs gave important insights to the research group, but a few crucial design faults unfortunately made it impossible to evaluate the full potential of the two designs.
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Hörmann, Wolfgang, and Gerhard Derflinger. "A portable uniform random number generator well suited for the rejection method." Institut für Statistik und Mathematik, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 1992. http://epub.wu.ac.at/1288/1/document.pdf.
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Up to now all known efficient portable implementations of linear congruential random number generators with modulus 2^(31)-1 are working only with multipliers which are small compared with the modulus. We show that for non-uniform distributions, the rejection method may generate random numbers of bad quality if combined with a linear congruential generator with small multiplier. Therefore a method is described that works for any multiplier smaller than 2^(30). It uses the decomposition of multiplier and seed in high order and low order bits to compute the upper and the lower half of the product. The sum of the two halfs gives the product of multiplier and seed modulo 2^(31)-1. Coded in ANSI-C and FORTRAN77 the method results in a portable implementation of the linear congruential generator that is as fast or faster than other portable methods. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processing
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Eriksson, Mikael. "Modelling and Experimental Verification of Direct Drive Wave Energy Conversion : Buoy-Generator Dynamics." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7785.
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This thesis is focused on development of models and modelling of a wave energy converter in operation. Through the thesis linear potential wave theory has been used to describe the wave-buoy interaction. The differences lie in the generator models, in the simplest model the generator is a mechanical damper characterized by a damping factor. In the most advanced generator model the magnetic fields is calculated the by a FE-method, which gives detailed description of the electric properties and the effect it has on the buoy dynamics. Moreover, an equivalent circuit description of the generator has been tested. It has the same accuracy as the field based model but with a strongly enhanced CPU time. All models are verified against full scale experiments. The models are intended to be used for design of the next generation wave energy converters. Further, the developed models have also been used to study what effect buoy geometry and generator damping have on the ability to energy absorption. In the spring 2006 a full scale wave energy converter was installed at the west coast of Sweden. It was in operation and collected data during three months. During that period the load resistance was varied in order to study the effect on the energy absorption. These collected data was then used in the verification of the developed models. In the year 2002 a wave energy project started at Uppsala University; this work is a part of that larger project which intendeds to develop a viable wave energy conversion concept.
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Thorburn, Karin. "Electric Energy Conversion Systems : Wave Energy and Hydropower." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7081.
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Hörmann, Wolfgang. "A note on the quality of random variates generated by the ratio of uniforms method." Institut für Statistik und Mathematik, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 1993. http://epub.wu.ac.at/1440/1/document.pdf.
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The one-dimensional distribution of pseudo-random numbers generated by the ratio of uniforms methods using linear congruential generators (LCGs) as the source of uniform random numbers is investigated in this paper. Due to the two-dimensional lattice structure of LCGs there is always a comparable large gap without a point in the one-dimensional distribution of any ratio of uniforms method. Lower bounds for these probabilities only depending on the modulus and the Beyer quotient of the LCG are proved for the case that the Cauchy the normal or the exponential distribution are generated. These bounds justify the recommendation not to use the ratio of uniforms method combined with LCGs. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processing
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Lejerskog, Erik. "Theoretical and Experimental Analysis of Operational Wave Energy Converters." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-274635.
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This thesis studies wave energy converters developed at Uppsala University. The wave energy converters are of point absorbing type with direct driven linear generators. The aim has been to study generator design with closed stator slots as well as offshore experimental studies. By closing the stator slots, the harmonic content in the magnetic flux density is reduced and as a result the cogging forces in the generator are reduced as well. By reducing these forces, the noise and vibrations from the generator can be lowered. The studies have shown a significant reduction in the cogging forces in the generator. Moreover, by closing the slots, the magnetic flux finds a short-cut through the closed slots and will lower the magnetic flux linking the windings. The experimental studies have focused on the motion of the translator. The weight of the translator has a significant impact on the power absorption, especially in the downward motion. Two different experiments have been studied with two different translator weights. The results show that with a higher translator weight the power absorption is more evenly produced between the upward and downward motion as was expected from the simulation models. Furthermore, studies on the influence of the changing active area have been conducted which show some benefits with a changing active area during the downward motion. The experimental results also indicate snatch-loads for the wave energy converter with a lower translator weight. Within this thesis results from a comparative study between two WECs with almost identical properties have been presented. The generators electrical properties and the buoy volumes are the same, but with different buoy heights and diameters. Moreover, experimental studies including the conversion from AC to DC have been achieved. The work in this thesis is part of a larger wave power project at Uppsala University. The project studies the whole process from the energy absorption from the waves to the connection to the electrical grid. The project has a test-site at the west coast of Sweden near the town of Lysekil, where wave energy systems have been studied since 2004.
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Lindroth, [formerly Tyrberg] Simon. "Buoy and Generator Interaction with Ocean Waves : Studies of a Wave Energy Conversion System." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160085.
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On March 13th, 2006, the Division of Electricity at Uppsala University deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that have published descriptions of on-site wave energy measurements.
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Fletcher, Nathan James. "Design and Implementation of Periodic Unsteadiness Generator for Turbine Secondary Flow Studies." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1560810428267352.
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Harischandra, Nalin. "Computer Simulation of the Neural Control of Locomotion in the Cat." Licentiate thesis, Stockholm : Numerisk analys och datalogi, Numerical Analysis and Computer Science, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4692.
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Murari, André Luiz de Lacerda Ferreira. "Regulador quadrático linear ponderado com otimização por enxame de partículas modificado aplicado a geradores de indução com rotor bobinado." reponame:Repositório Institucional da UFABC, 2018.
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Orientador: Prof. Dr. Alfeu Joãzinho Sguarezi FilhoCoorientador: Prof. Dr. José Alberto Torrico Altuna
Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, Santo André, 2018.
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Curto, Domenico. "DESALINATION AND SEA WAVE TO PRODUCE FRESHWATER AND ENERGY FROM THE SEA. THE PROPOSAL OF A LINEAR GENERATOR FOR A WAVE ENERGY CONVERTER AND EVALUATION OF CASE STUDIES IN SMALL ISLANDS." Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/395426.
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Oliveira, José Mário Menescal de. "Efeitos da operação do gerador de indução no comportamento do gerador síncrono operando em um sistema isolado alimentando cargas não lineares." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8878.
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This thesis demonstrates the effects of harmonic pollution in a salient pole synchronous generator and an induction generator operating in parallel on an isolated system, supplying a non-linear load. The main contributions of this research-study consist of identifying and quantifying the oscillations that non-linear load cause on the electric variables of synchronous and induction generators, such as, the electromagnetic conjugate that presents oscillations of sixth harmonic due to the distorted currents.
Este trabalho mostra os efeitos da poluição harmônica em um gerador síncrono de polos salientes e um gerador de indução operando em paralelo em um sistema isolado suprindo carga não linear. As principais contribuições deste trabalho consistem em identificar e quantificar as oscilações que a carga não linear utilizada provoca nas variáveis elétricas dos geradores síncronos e dos geradores de indução, tal como, o conjugado eletromagnético que apresenta oscilações de sexto harmônico devido as correntes distorcidas.
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Zulkifli, Shamsul. "Energy recovery from landing aircraft." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10843.
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Currently, renewable energy sources are the main driver for future electricity generation. This trend is growing faster in the developed countries in order to reduce the green house effect and also in response to the limited supply of oil, gas and coal which are currently the major sources for electric generation. For example, the main renewable energy sources are from wind energy and solar energy but these energies are only available to those countries that are exposed to these resources. In this thesis an alternative energy source is investigated where it can be generated from the moving objects or in form of kinetic energy. The idea is to convert the kinetic energy during landing aircraft into electrical energy which it can also be stored and transferred to the existing electrical network. To convert this kinetic energy to electrical energy, the linear generator (LG) and uncontrolled rectifier have been used for energy conversion. The LG have been modelled in 3-phase model or in dq model and combined with the diode rectifier that is used to generate the dc signal outputs. Due to the uncontrolled rectifier the electrical outputs will have decaying amplitude along the landing time. This condition also happen to the LG outputs such as the force and the power output. In order to control these outputs the cascaded buck-boost converter has been used. This converter is responsible to control the output current at the rectifier and also the LG output power during landing to more controllable power output. Here, the H∞ current control strategy has been used as it offers a very good performance for current tracking and to increase the robustness of the controller. During landing, huge power is produced at the beginning and when the landing time is increased, the generated input power from LG is reduced to zero. Due to this, the energy storage that consists of ultracapacitor, bidirectional converter and boost converter are used in order to store and to release the energy depends on the input power source and load grid power. The voltage proportional-integral (PI) control strategy has been used for both the converters. The last part is to transfer the energy from the source and at the ultracapacitor to the load by using the inverter as the processing device. The power controller and current controller are used at the inverter in order to control the power ?ow between the inverter and the grid. This is when the reference power is determined by the load power in order to generate the reference currents by using the voltage oriented controller (VOC), while the H∞ current controller is used to regulate the inverter currents in order to inject the suitable amount of current that refer to the load power. Finally, a complete energy recovery system for landing aircraft with the grid connection have been put together to make the whole system to be as a new renewable energy source for the future electricity generation.
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Simpson, Leonie Ruth. "Divide and conquer attacks on shift register based stream ciphers." Thesis, Queensland University of Technology, 2000.
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François, Pierre. "Contribution à la modélisation électromagnétique d’un générateur linéaire à induction appliquée à un micro-cogénérateur Stirling à piston libre." Thesis, Cachan, Ecole normale supérieure, 2011. http://www.theses.fr/2011DENS0003.
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Cette thèse porte sur le développement d’un cogénérateur résidentiel constitué d’un générateur linéaire asynchrone entraîné par deux moteurs Stirling fonctionnant en mode ‘piston libre double effet’. Les critères caractérisant un tel cogénérateur sont décrits ainsi que ses différents modes d’utilisation dans le domaine résidentiel. Les différentes technologies sont passées en revue.Les équations de la mécanique sur lesquelles se fondent le contrôle du couplage thermoélectrique du cogénérateur et sa stabilité y sont définies. Le générateur électrique est modélisé en vue de calculer les grandeurs électriques des équations à bobines couplées et les grandeurs du schéma électrique équivalent, ce schéma permet d’inverser le modèle.Les résultats des modèles analytiques sont validés par des mesures faites sur des maquettes spécialement conçues. Une étude paramétrique de la structure du générateur a permis d’optimiser ses performances. Les équations de la mécanique et le modèle électrique sont utilisés pour poser les bases d’une optimisation ‘système’ du cogénérateurThis thesis focuses on the development of a residential cogenerator which consists of a linear induction generator driven by two Stirling engines, free-piston double-acting operating mode. The criteria characterizing such cogenerator are described and its various modes of use in the residential sector. The various technologies are reviewed.The equations of mechanics that underlie the control of the coupling of thermoelectric cogeneration and stability are defined.The electric generator is modeled to calculate the electrical coil coupled equations and the magnitudes of the equivalent circuit, this scheme allows us to reverse the pattern. The results of analytical models are validated by measurements on specially designed models. A parametric study of the structure of the generator has optimized its performances. The equations of mechanical and electrical model are used to lay the groundwork for optimization of all the cogenerator, considered as a system
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Engström, Jens. "Hydrodynamic Modelling for a Point Absorbing Wave Energy Converter." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160319.
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Surface gravity waves in the world’s oceans contain a renewable source of free power on the order of terawatts that has to this date not been commercially utilized. The division of Electricity at Uppsala University is developing a technology to harvest this energy. The technology is a point absorber type wave energy converter based on a direct-driven linear generator placed on the sea bed connected via a line to a buoy on the surface. The work in this thesis is focused mainly on the energy transport of ocean waves and on increasing the transfer of energy from the waves to the generator and load. Potential linear wave theory is used to describe the ocean waves and to derive the hydrodynamic forces that are exerted on the buoy. Expressions for the energy transport in polychromatic waves travelling over waters of finite depth are derived and extracted from measured time series of wave elevation collected at the Lysekil test site. The results are compared to existing solutions that uses the simpler deep water approximation. A Two-Body system wave energy converter model tuned to resonance in Swedish west coast sea states is developed based on the Lysekil project concept. The first indicative results are derived by using a linear resistive load. The concept is further extended by a coupled hydrodynamic and electromagnetic model with two more realistic non-linear load conditions. Results show that the use of the deep water approximation gives a too low energy transport in the time averaged as well as in the total instantaneous energy transport. Around the resonance frequency, a Two-Body System gives a power capture ratio of up to 80 percent. For more energetic sea states the power capture ratio decreases rapidly, indicating a smoother power output. The currents in the generator when using the Two-Body system is shown to be more evenly distributed compared to the conventional system, indicating a better utilization of the electrical equipment. Although the resonant nature of the system makes it sensitive to the shape of the wave spectrum, results indicate a threefold increase in annual power production compared to the conventional system.
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Elmes, John. "MAXIMUM ENERGY HARVESTING CONTROL FOROSCILLATING ENERGY HARVESTING SYSTEMS." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3400.
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This thesis presents an optimal method of designing and controlling an oscillating energy harvesting system. Many new and emerging energy harvesting systems, such as the energy harvesting backpack and ocean wave energy harvesting, capture energy normally expelled through mechanical interactions. Often the nature of the system indicates slow system time constants and unsteady AC voltages. This paper reveals a method for achieving maximum energy harvesting from such sources with fast determination of the optimal operating condition. An energy harvesting backpack, which captures energy from the interaction between the user and the spring decoupled load, is presented in this paper. The new control strategy, maximum energy harvesting control (MEHC), is developed and applied to the energy harvesting backpack system to evaluate the improvement of the MEHC over the basic maximum power point tracking algorithm.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
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Rusková, Miroslava. "Elektromagnetický rezonátor jako zdroj elektrické energie na železniční trati." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378736.
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The aim of the diploma thesis was to design an electromagnetic generator to the purpose of supplying signalling and safety devices on the rail tracks. The electromagnetic generator is a separate electrical source, which is mainly needed for safety in the case of not covered tracks by electrical installation. The thesis proposes two types of electromagnetic generator and one with non-linear stiffness, which are designed for the passage of trains with low frequency.
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Healy, Strömgren William. "Automatic Adjustment of the Floatation Level for a Tight-moored Buoy." Thesis, Uppsala University, Department of Earth Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88883.
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Denna rapport ger förslag på olika metoder att automatiskt justera flytläget på en statiskt förankrad boj, en överblick över de processer som styr ändringen av vattennivån och en statisktisk analys på vattennivåförändringarna vid Stockholm, Kungsholmsfort och Kungsvik.
Beroende på vattenivåns variation finns olika metoder för justering. Områden med små variationer av vattennivå lämpar det sig bäst utan någon som helst justering av flytläget. Områden med inte för stora tidvattensförändringar bör justeras med ett system bestående av vinsch, växellåda med en utväxling på 10 000:1, en 12 V DC motor, ett skötselfritt 12 V batteri, en luftlindad linjärgenerator och en trådtöjningsgivare. Områden med stora variationer i tidvatten behöver en avlastning för motorn i form av en fjäder och dämpare. De monteras horizontellt inuti bojen för att skyddas från den yttre miljön.
Den statistiska analysen påvisade de största vattennivåändringarna vid både Kungsviks och Kungsholmsforts mätstationer, båda uppvisade ett intervall på 1,6 m mellan minimum och maximum. Kungsvik var den station med de största dagliga variationerna, detta på grund av tidvattnets påverkan i området.
This thesis gives examples of different methods of automated adjustment of floatation level for a static moored buoy, an overview of the theories behind water level change and a statistical analysis of the water level changes for Stockholm, Kungsholmsfort and Kungsvik.
Depending on the range and frequency of the water level change different methods of adjustment are recommended. For areas with small changes in sea level the best choice would be no adjustment of the floatation level. Areas that are influenced by moderate tidal ranges should incorporate a system of regulation consisting of a winch, gearbox with a gear ratio of around 10,000:1, 12 V DC motor, 12 V maintenance free battery, air coiled linear generator and a strain gauge. For areas with large tidal ranges the previous system should be complimented with a horizontally mounted spring, inside the buoy, to lessen the loads on the motor.
The statistical analysis found the largest extremes in water level of the three sites to be at Kungsvik and Kungsholmsfort, both exhibiting a range of almost 1.6 m. Kungsvik was the station with the largest daily variations, this is because this is the only station influenced by tidal variations.
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Waters, Rafael. "Energy from Ocean Waves : Full Scale Experimental Verification of a Wave Energy Converter." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9404.
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A wave energy converter has been constructed and its function and operational characteristics have been thoroughly investigated and published. The wave energy converter was installed in March of 2006 approximately two kilometers off the Swedish west coast in the proximity of the town Lysekil. Since then the converter has been submerged at the research site for over two and a half years and in operation during three time periods for a total of 12 months, the latest being during five months of 2008. Throughout this time the generated electricity has been transmitted to shore and operational data has been recorded. The wave energy converter and its connected electrical system has been continually upgraded and each of the three operational periods have investigated more advanced stages in the progression toward grid connection. The wave energy system has faced the challenges of the ocean and initial results and insights have been reached, most important being that the overall wave energy concept has been verified. Experiments have shown that slowly varying power generation from ocean waves is possible. Apart from the wave energy converter, three shorter studies have been performed. A sensor was designed for measuring the air gap width of the linear generator used in the wave energy converter. The sensor consists of an etched coil, a search coil, that functions passively through induction. Theory and experiment showed good agreement. The Swedish west coast wave climate has been studied in detail. The study used eight years of wave data from 13 sites in the Skagerrak and Kattegatt, and data from a wave measurement buoy located at the wave energy research site. The study resulted in scatter diagrams, hundred year extreme wave estimations, and a mapping of the energy flux in the area. The average energy flux was found to be approximately 5.2 kW/m in the offshore Skagerrak, 2.8 kW/m in the near shore Skagerrak, and 2.4 kW/m in the Kattegat. A method for evaluating renewable energy technologies in terms of economy and engineering solutions has been investigated. The match between the technologies and the fundamental physics of renewable energy sources can be given in terms of the technology’s utilization. It is argued that engineers should strive for a high utilization if competitive technologies are to be developed.
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Біровець, Іван Іванович, and Ivan Birovets. "Розробка системи електроводопостачання віддалених споживачів з допомогою енергії вітру." Bachelor's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2021. http://elartu.tntu.edu.ua/handle/lib/35523.
Full textAbstract:
Зaпpoпoнoвaнo нoвe кoнcтpуктивнe piшeння кoмбiнoвaнoї eлeктpoвoдo пocтaчaльнoї вiтpoуcтaнoвки, у якiй вiтpoдвигун, щo мaє кpивoшипнo-пoвзункoвий
мeхaнiзм з oб’ємним вoдяним нacocoм i мaгнiтoeлeктpичним лiнiйним
гeнepaтopoм, щo хapaктepизуєтьcя виcoким ККД тa мoжливicтю eфeктивнoгo
викopиcтaння мeхaнiчнoї eнepгiї вiтpoдвигунa для гeнepувaння eлeктpичнoї eнepгiї
тa пiдняття вoди з джepeлa. Зaпpoпoнoвaнo cтpуктуpнo-функцioнaльну cхeму кoмбiнoвaнoї
eлeктpoвoдoпocтaчaльнoї вiтpoуcтaнoвки, здiйcнeнo oпиc ocнoвних вузлiв тa
нaвeдeнo пpинцип poбoти. Poзpoблeнo eфeктивну кoнcтpукцiї тa здiйcнeнo oпиc ocнoвних eлeмeн тiв
тa aлгopитму poбoти мaгнiтoeлeктpичнoгo лiнiйнoгo гeнepaтopa.Кваліфікаційна робота присвячена науково-технічним принципам побудови комбінованих електроводопостачальних вітроустановок на базі магнітоелектричних лінійних генераторів. В роботі вперше обґрунтовано комплекс електромеханічних та електромагнітних процесів електротехнічного комплексу на базі магніто-електричного лінійного генератора зворотно-поступального (МЕЛГ) руху з урахуванням режимів електроводоспоживання та стохастичного надходження енергії вітру для підвищення енергоефективності комбінованої електроводопостачальної вітроустановки. Впровад-ження результатів дослідження дозволить забезпечити розв’язання задачі електроводо-постачання споживачів фермерських господарств з використанням поновлюваних джерел енергії. Дипломна робота присвячена науково-технічним принципам побудови комбінованих електроводопостачальних вітроустановок на базі магнітоелектричних лінійних генераторів.
The thesis is devoted to the scientific and technical principles of construction of combined electric-supplying wind turbines based on magneto-electric linear generators. In the work for the first time the complex of electromechanical and electromagnetic processes of the electrotechnical complex on the basis of the magneto-electric linear generator of the reciprocating (MELG) motion based on the modes of electric consumption and stochastic inflow of wind power for increasing energy efficiency of the combined electric-supply winding installation is grounded. the implementation of the research results will allow solving the problem of electricity supply to consumers of farms with the use of renewable energy sources.
ПEPEЛIК УМOВНИХ CКOPOЧEНЬ 6 ВCТУП 7 1 AНAЛIТИЧНИЙ POЗДIЛ 9 1.1 Oцiнкa нaукoвo-мeтoдичнoї бaзи дocлiджeнь вiтpoeлeктpoнacocних i вiтpoнacocних уcтaнoвoк тa визнaчeння шляхiв пiдвищeння eнepгoeфeктивнocтi їх функцioнувaння 9 1.2 Пocтaнoвкa зaдaчi дo пpoeктувaння 18 2 ПPOEКТНO-КOНCТPУКТOPCЬКИЙ POЗДIЛ 19 2.1 Poзpoбкa функцioнaльнoї cхeми тa oпиc ocнoвних вузлiв КEВВУ 19 2.2 Нeoбхiднicть викopиcтaння aкумулятopних бaтapeй у КEВВУ 23 2.3 Пpoeктувaння eфeктивнoї кoнcтpукцiї мaгнiтoeлeктpичнoгo лiнiйнoгo гeнe paтopa 27 2.4 Aлгopитм кepувaння мaгнiтoeлeктpичним лiнiйним гeнepaтopoм 32 2.5 Oбґpунтувaння пoкaзникiв eнepгoeфeктивнocтi cтpуктуpних eлeмeнтiв КEВВУ 33 2.6 Виcнoвки дo poздiлу 2 36 3 POЗPAХУНКOВO-ДOCЛIДНИЦЬКИЙ POЗДIЛ 37 3.1 Визнaчeння тpивaлocтi бeзпepepвнoгo пpoцecу aвтoнoмнoгo живлeння eлeктpocпoживaчiв вiд aкумулятopних бaтapeй КEВВУ 37 3.2 Дocлiджeння eнepгeтичних хapaктepиcтик мaгнiтoeлeктpичнoгo лiнiйнoгo гeнepaтopa звopoтнo-пocтупaльнoгo pуху 47 3.3 Poзpaхунoк тeхнiкo-eкoнoмiчнoї eфeктивнocтi впpoвaджeння КEВВУ 54 3.4 Виcнoвки дo poздiлу 3 56 4 БEЗПEКA ЖИТТЄДIЯЛЬНOCТI ТA OCНOВИ OХOPOНИ ПPAЦI 57 4.1 Пpaвилa бeзпeки пpи eкcплуaтaцiї eлeктpoвoдoпocтaчaльних cиcтeм 57 4.2 Пpaвилa бeзпeки пpи eкcплуaтaцiї aкумулятopних бaтapeй 59 4.3 Зaхиcт пepcoнaлу тa нaвкoлишньoгo cepeдoвищa вiд шумiв тa вiбpaцiй пpи poбoтi вiтpoeнepгeтичних уcтaнoвoк 61 ЗAГAЛЬНI ВИCНOВКИ 64 ПEPEЛIК ПOCИЛAНЬ 66
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Park, Youngmin. "Infinitesimal Phase Response Curves for Piecewise Smooth Dynamical Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1370643724.
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