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  • 1.
    Ackermann, Thomas
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Distributed Resources in a Re-Regulated Market Environment2004Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis analyses the value that distributed resources(DR) can contribute to an economically effcient operation of are-regulated electricity market and discusses the relevantchanges in the regulatory framework to allow the appropriatedevelopment of DR whenever DR may increase the economiceffciency of the electricity market.

    Distributed resources thereby combine two aspects:Distributed generation and demand-side resources. Distributedgeneration is defined as generation within the distributionsystem or on the customer side of the meter. Demand-sideresources are those load resources on the customer-side thatcan be used to shift electricity demand from peak to off-peakperiods, or to reduce the overall electricity demand.

    To gain a better understanding of the value that DR mayprovide in a re-regulated market, an analysis of there-regulation approaches in England andWales, Scandinavia,Australia, New Zealand as well as in two regions in the USA isperformed. The key findings of this analysis are that non ofthe re-regulation approaches put special emphasis on DR. Thecomparison also shows that despite very different approachesused in the various markets, the remaining re-regulationproblems are very similar. These key problems are mainlyrelated to market power in the various markets and littlecompetition in network services.

    The thesis shows that DR has the potential to improveoverall economic market effciency by reducing market powerissues and increasing competition in network services. Forinstance, many DR business schemes have no incentive toexercise market power, because withholding generation may havea negative impact on the complex revenue stream from differentincome sources. While this may not allow the general conclusionthat DR will always provide benefits to market operation, it isimportant to consider that not all DR need to provide suchbenefits, as it was also shown that already comparatively smallamounts of demand resources or distributed generation cansignificantlyreduce market power issues. In addition, it wasalso shown that DR can introduce competition into networkservices and therefore can provide incentives for distributionand transmission network companies to operate more costeffectively.

    It was also demonstrated that the potential of DR to improveoverall economic market effciency will only be realized if:

    1. DR is developed in the correct size, i.e. DR should fitinto an existing distribution network and may increase networkutilization rate,2. DR is developed at the correct location in thenetwork, e.g. in areas with congestion problems,3. DR is in operation during the correct times, whenbeneficial to the market, e.g. during times when market powerissues may arise, and4. independent ownership of DR projects isencouraged.

    Market regulations therefore must provide the correctincentives for the correct siting and operation of DR as wellas for independent ownership. The thesis uses examples andempirical data to explain the relevant regulatory aspects indetail and provides suggestions for a regulatory framework thatconsiders the potential of DR to improve overall economiceffciency in an electricity market.

  • 2.
    Agrén, Ola
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Losses and thermal analysis of a high-speed PM generator for miccroturbines2003Doktoravhandling, med artikler (Annet vitenskapelig)
  • 3.
    Amelin, Mikael
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    On Monte Carlo simulation and analysis of electricity markets2004Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This dissertation is about how Monte Carlo simulation can be used to analyse electricity markets. There are a wide range of applications for simulation; for example, players in the electricity market can use simulation to decide whether or not an investment can be expected to be profitable, and authorities can by means of simulation find out which consequences a certain market design can be expected to have on electricity prices, environmental impact, etc.

    In the first part of the dissertation, the focus is which electricity market models are suitable for Monte Carlo simulation. The starting point is a definition of an ideal electricity market. Such an electricity market is partly practical from a mathematical point of view (it is simple to formulate and does not require too complex calculations) and partly it is a representation of the best possible resource utilisation. The definition of the ideal electricity market is followed by analysis how the reality differs from the ideal model, what consequences the differences have on the rules of the electricity market and the strategies of the players, as well as how non-ideal properties can be included in a mathematical model. Particularly, questions about environmental impact, forecast uncertainty and grid costs are studied.

    The second part of the dissertation treats the Monte Carlo technique itself. To reduce the number of samples necessary to obtain accurate results, variance reduction techniques can be used. Here, six different variance reduction techniques are studied and possible applications are pointed out. The conclusions of these studies are turned into a method for efficient simulation of basic electricity markets. The method is applied to some test systems and the results show that the chosen variance reduction techniques can produce equal or better results using 99% fewer samples compared to when the same system is simulated without any variance reduction technique. More complex electricity market models cannot directly be simulated using the same method. However, in the dissertation it is shown that there are parallels and that the results from simulation of basic electricity markets can form a foundation for future simulation methods.

    Keywords: Electricity market, Monte Carlo simulation, variance reduction techniques, operation cost, reliability.

  • 4.
    Andersson, Jonas
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Enterprise Information Systems Management: An Engineering Perspective Focusing on the Aspects of Time and Modifiability2002Doktoravhandling, med artikler (Annet vitenskapelig)
  • 5. Andersson, Jonas
    et al.
    Johnson, Pontus
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Architectural integration styles for large scale enterprise software systems2001Inngår i: Proceedings of the 5th IEEE International Conference on Enterprise Distributed Object Computing, 2001Konferansepaper (Annet vitenskapelig)
  • 6. Andersson, Jonas
    et al.
    Johnson, Pontus
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Extending attribute based architectural analysis to enterprise software systems2000Inngår i: Proceedings of the 3rd Australasian Workshop on Software and System Architectures, 2000Konferansepaper (Annet vitenskapelig)
  • 7. Andersson, Jonas
    et al.
    Johnson, Pontus
    KTH, Tidigare Institutioner, Elektrotekniska system.
    IT Infrastructure Architectures for Electric Utilities: A Comparative Analysis of Description Techniques2000Inngår i: Proceedings of the Annual Hawaii International Conference on System Sciences, ISSN 1530-1605, Vol. 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The escalating development of Information Technology enables utilities to reorganize or migrate from their existing disparate software systems towards an integrated Enterprise Software System Infrastructure (ESSI) that embraces the total organization. Integration of software systems is expected to increase competitiveness and to cut costs. However, since utilities' present ESSI is heterogeneous as to type and technical platform, overlapping with regard to both data and functionality, and relying on ad-hoc low-level middleware, integration and management of ESSIs often turn out to be hazardous.This paper presents a comparative analysis of the architectural modeling capabilities of established notations widely used by object-oriented, information engineering and structured methods, applied to typical problems found in utilities' ESSI. Architectural descriptions may be used to visualize technical risks and opportunities in a utility's current and future ESSI, as well as to improve communication between different groups within the utility, e.g. management and technical staff, and between the utility and its vendors of software systems.

  • 8.
    Anpalahan, Peethamparam
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Design of transverse flux machines using analytical calculations&finite element Analysis2001Licentiatavhandling, monografi (Annet vitenskapelig)
  • 9.
    Arshad, W. M.
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Thelin, Peter
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Sadarangani, Chandur
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Bäckström, T.
    Analytical analysis and dimensioning of a low-leakage linear transverse-flux machine2004Inngår i: IEE Conference Publication, 2004, s. 414-419Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a two-dimensional analytical analysis and dimensioning procedure of a novel low-leakage linear transverse-flux machine (TFM). The two-dimensionalanalytical models approximate the complex three-dimensional fluxes of the TFM. Theanalysis is based upon how the different airgap permeances and the non-linear iron reluctances in the different machine sections vary, as the translator is traversed through the airgap. The reluctance networks for the magnetomotive force (MMF) of the magnets and for the current dependent armature-MMF are solved simultaneously. A 5-kW proof-of-concept machine is dimensioned and its performance predicted using the described procedure. The different performance defining parameters are derived as continuous functions of the translator position. The dependence of the machine power factor and the force capability upon the current loading, which is quite interesting when analysing TFMs, is also investigated.

  • 10.
    Arshad, Waqas
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    A Low-Leakage Linear Transverse-Flux Machine for a Free-Piston Generator2003Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The presented work is about a new low-leakage lineartransverse-flux electrical machine.The machine is dimensionedfor a free-piston generator. The intended application is inseries-hybrid vehicles. The free-piston generator is anintegration of a free-piston combustion engine with a linearelectrical machine. It provides benefits in e±ciency,emissions and multi-fuel capabilities, to name a few. Thesecombustion benefits are only possible if the total mover massis kept quite low (e.g.&#8804 4 kg for a 50 kW unit). Thelimited mover mass and competitiveness demands result in a verystringent set of specifications for the electrical machine.

    Most existing electrical machine topologies arepreliminarily investigated. Of these only a transverse-fluxmachine (TFM) is found to be promising. Even for the case ofthe TFM, a factor 2 improvement in the performance indices ofthe existing TFMs is required. Different surface-mounted TFMsare investigated for improvement. It is found that theanalytically acceptable solutions fail during thethree-dimensional finite-element analysis (3D-FEM). Thesedesigns suffer from a very significant pole-to-pole armatureleakage flux in the stator. Similar design improvements for theburied-magnets TFMs are also investigated. Fortunately, in thiscase a promising design is derived. This design exhibits lowleakage and is verified with FEM analysis. A down-scaledone-phase 1.7 kW proof-of-concept TFM of this design isdimensioned. It is analysed thoroughly, both analytically aswell as by 3D-FEM computations. It is found that for thisparticular prototype the design suffered from saturation. It isshown how this design can be modified to yield the desiredforce with the allowed mover mass. The efficiency is found tobe only slightly lower than the demands but a poor power factoris noted.

    The prototype is built. Unfortunately, all the desiredmeasurements could not be carried out. This is because thebuilt-machine sufferedwith two major manufacturing defects.The magnets are found to be demagnetised to about 50% of theirmanufactured value. It is also found that the translator poleson the average are 7% longer (in the axial direction) than thestator poles. Low values of no-load induced voltage and forceare thus measured. The correlation between the manufacturingdefects and the measurements is established. Due toinsufficient measurement data, this relationship is mainly ofan indicative nature only. A more correct picture requiresconstruction of a new prototype. Still, the results do pointtowards a near fulfillment of the objectives. Other addressedtopics include, an investigation into a separate free-pistongenerator project with reduced specifications, application ofthe presented work to renewable energy sources like wind- andwave-energy and a brief introduction to the free-pistonapplication aspects.

    Keywords:Free-Piston Generators, Linear Machines,Transverse-Flux Machines, Hybrid Vehicles, Electrical MachinesDesign.

  • 11.
    Arshad, Waqas M.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Thelin, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik.
    Bäckström, T.
    Sadarangani, Chandur
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Use of transverse-flux machines in a free-piston generator2004Inngår i: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 40, nr 4, s. 1092-1100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates the use of transverse-flux machines (TFMs) in a free-piston generator, an integration of a combustion engine and a linear electrical machine. For hybrid vehicles (the intended application), this integrated device has benefits in efficiency, emissions, reliability, etc. Conventional TFMs are dimensioned and their shortcomings illustrated. Several surface-mounted TFM designs are suggested. These designs, initially believed to be promising, are later discovered to be. poor during the three-dimensional finite-element method (3-D FEM) analysis. These designs suffered from a large axial pole-to-pole armature-flux leakage in the stator. This problem is solved in the proposed buried-magnets TFM variants, for which patents have been filed as well. A 5-kW proof-of-concept prototype of one such design is dimensioned that allowed the near fulfilment of 3-D FEM verifiable system demands. One phase. of this dimensioned three-phase prototype is built. Measurements on this,prototype showed that the use of short pole lengths in the machine had led to manufacturing defects. Nevertheless, the electromagnetic viability of the design could still be approximately verified.

  • 12.
    Arshad, Waqas Mahmood
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Thelin, Peter
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Modelling of complex flux paths in a new high-performance transverse-flux electrical machine2004Inngår i: SECOND SEEHEIM CONFERENCE ON MAGNETISM, PROCEEDINGS / [ed] Ghafari, M; Enz, T; Hahn, H, WEINHEIM: WILEY-V C H VERLAG GMBH , 2004, s. 3227-3234Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The complex three-dimensional fluxes in a newly introduced high-performance transverse-flux electrical machine are investigated. The magnet-flux, the armature-flux and the combined-flux in the machine are studied as a function of mover position. Separate non-linear reluctance networks for the magnets- and current- magneto-motive forces are developed and solved simultaneously in an iterative manner. The airgap is modelled by defining two/three-dimensional varying permeances. The iron is represented with three different non-linear reluctances. The analytical models are fine tuned and verified by employing a detailed three-dimensional finite element analysis. The role these fluxes play in the determination of the machine's performance is also described. Lastly, it is shown how these fluxes help explain the machines' measured performance when unexpected manufacturing defects occurred.

  • 13. Austrin, L.
    et al.
    Krah, Julius Hartwig
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Engdahl, Göran
    KTH, Tidigare Institutioner, Elektrotekniska system.
    A modeling approach of a magnetic amplifier2004Inngår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 272, s. E1709-E1710Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New soft magnetic materials made possible the use of the magnetic amplifier technology in designing competitive electric power supplies. This technology is used in the Swedish. fighter aircraft Gripen, being also attractive for future more electrical aircraft systems due to the possibility to achieve a compact and robust design. A modeling approach of a magnetic amplifier based on the magnetic hysteresis of the core material is presented here for a common amorphous magnetic alloy.

  • 14. Austrin, Lars
    et al.
    Krah, Julius
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Engdahl, Göran
    KTH, Tidigare Institutioner, Elektrotekniska system.
    A Modeling Approach of a Magnetic Amplifier2003Inngår i: Proc. on ICM 2003 International Conference on Magnetism, Rome, Italy, 2003Konferansepaper (Fagfellevurdert)
  • 15. Berg, Niklas
    et al.
    Erikssson, Sture
    Sadarangani, Chandur
    Bäckström, Thomas
    Östlund, Stefan
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Malmqvist, Anders
    Hybriddrivanordning samt hjulfordon försett med en hybriddrivanordning1998Patent (Annet (populærvitenskap, debatt, mm))
  • 16.
    Bergkvist, Tommy
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Hellsten, Torbjörn
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Self-consistent calculations of the distribution function and wave field during ICRF heating and global Alfvén wave excitation2004Inngår i: Proceeding of Theory of Fusions Plasmas, 2004, s. 123-132Konferansepaper (Fagfellevurdert)
  • 17. Bergqvist, A. J.
    et al.
    Engdahl, Göran
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    A homogenization procedure of field quantities in laminated electric steel2001Inngår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 37, nr 5, s. 3329-3331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for representing structures of laminated electric steel is investigated. The average behavior of laminates, including eddy current effects, is approximately represented using a rate-dependent constitutive law. The accuracy of the method is studied by comparing the homogenized description with finite difference calculations.

  • 18.
    Bertling, Lina
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Impact of maintenance on cable failure rates2004Inngår i: 2004 IEEE POWER ENGINEERING SOCIETY GENERAL MEETING, VOLS 1 AND 2, NEW YORK: IEEE , 2004, s. 704-704Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This panel presentation discusses the development of a functional relationship between failure rates and maintenance measures for insulated cables. The approach has been applied to rural and urban distribution systems, and demonstrates the value of using a systematic quantitative approach for investigating the effect of different maintenance strategies.

  • 19.
    Bertling, Lina
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Reliability-centred maintenance for electric power distribution systems2002Doktoravhandling, monografi (Annet vitenskapelig)
  • 20.
    Bessegato, Luca
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Harnefors, Lennart
    Ilves, Kalle
    Norrga, Staffan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Östlund, Stefan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad. KTH, Tidigare Institutioner (före 2005), Elektrotekniska system. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG. KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930). KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling. KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Control of Direct AC/AC Modular Multilevel Converters Using Capacitor Voltage Estimation2016Inngår i: 2016 18TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'16 ECCE EUROPE), IEEE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper applies a control method based on current control and sum-capacitor-voltage estimation to the direct ac/ac modular multilevel converter. As capacitor voltages are estimated, their measurements are not needed in the high-level control, which simplifies the communication between the main controller and the submodules of the converter. The stability of the internal dynamics of the converter, using the aforementioned control method, is studied using Lyapunov stability theory, proving that the system is globally asymptotically stable. The behavior of the converter is simulated focusing on three-phase 50 Hz to single-phase 16 (2)/(3) Hz conversion, which is typical for railway power supply systems of some European countries. Simulation results are in agreement with the expected behavior of the converter, both in steady-state and dynamic situations.

  • 21.
    Bessegato, Luca
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Narula, Anant
    Bakas, Panagiotis
    Norrga, Staffan
    KTH, Tidigare Institutioner (före 2005), Elektrotekniska system. KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930). KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling. KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Design of a Modular Multilevel Converter Prototype for Research Purposes2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As modular multilevel converters gradually become the preferred topology for many high-voltage andhigh-power applications, they are widely studied among researchers, who need experimental results tovalidate their studies. This paper discusses the design of a down-scaled modular multilevel converterprototype for research purposes, equipped with 30 full-bridge submodules and 10 kW rating. The designof this prototype is aimed at safety, flexibility, orderliness, and compactness. The challenges posed by theimplementation of the converter prototype are examined, discussing the design of the prototype structure,the communication scheme, the full-bridge submodules, and the control hierarchy. The control systemis based on Xilinx Zynq system-on-chip, which integrates programmable logic and processing system,allowing for extensive computational capability as well as simple reconfiguration. Experimental resultsshowing the prototype in operation at nominal ratings are presented along with the devised graphical userinterface.

  • 22. Bjurman, U.
    et al.
    Engdahl, Göran
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Separation of high and low frequency behavior in non-linear circuit simulation, excited with modulated signals2000Inngår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 36, nr 4, s. 968-970Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exciting nonlinear circuits with modulated signals will generate crossmodulation frequencies. In ordinary simulation techniques this makes time stepping methods a necessity, In the case of EMC-testing where the carrier frequency is as high as 2 GHz and the modulating frequency only 1 kHz, the simulation time will be extremely long. This paper presents Time Domain Frequency Separation (TDFS), a method,where the high and low frequency behavior is calculated separately to decrease the computation time. In a simulation made with Saber the calculation took approximately fourteen hours, and with TDFS in Matlab two minutes.

  • 23.
    Brodén, Daniel
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Armendariz, Mikel
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. KTH, Tidigare Institutioner (före 2005), Elektrotekniska system. KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Anticipating Overrides of Schedulable Space Heating Systems in Detached Houses for Demand ResponseInngår i: Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    In this paper we propose and evaluate two cases of a model predictive scheduling approach to anticipate overrides of schedulable electric space heating systems in detached houses. We assume a demand-response set-up where the space heating systems of a population of heterogeneous detached houses are scheduled over a finite horizon with the objective of having their aggregated space heating load follow a desired load profile. We envision that the desired load profile provides hourly to sub-hourly ancillary services to electricity market actors and define schedule overrides as the interruption of demand response following a violation of the indoor temperature comfort in a house. We use a model to represent the indoor temperature change in detached houses on minute resolution which considers, among other variables, weather- and individual behavioral-related heat gains and losses in the building. The model predictive scheduling approach is evaluated on a use-case consisting of a balance responsible player looking to minimize its daily expected power imbalances on the intraday market. The scheduling is performed on 100 detached houses participating in demand-response for two predictive cases and a non-predictive case for comparison. The predictive cases differ in the level of information known about thebuilding attributes of the population. Simulations are performed for 90 consecutive days corresponding to a Swedish winter period where results indicate power imbalance reductions of up to 30% and notable differences between predictive cases.

  • 24.
    Carlsson, Fredrik
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Impacts of voltage sags on metal processes2001Licentiatavhandling, monografi (Annet vitenskapelig)
  • 25.
    Carlsson, Fredrik
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    On impacts and ride-through of voltage sags exposing line-operated AC-machines and metal processes2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    During the last decade, power quality has been recognised asa global problem. Among different types of power qualityproblems, voltage sags have been identified to be one of themost severe problems for different process industries. The mostcommon reason to voltage sags is lightning strikes in powerlines. Protection equipment, usually located at switchyards,disconnect faulted power lines as soon as possible, which isapproximately 100 ms. Thus, the duration of voltage sags areapproximately 100 ms. The sensitivity to voltage sags ofelectrical equipment in process industries can be observed asfor instance malfunction, automatic turnoff or damages.

    This thesis gives an overview of three metals processes withfocus on the sensitivity to voltage sags and interruptions. Theinherent energy in the process is used to find the sensitivity.This energy may also be used to obtain "ride-through" for theprocesses. The three metals processes are a blast furnaceprocess, a hot rolling mill process and a cold rolling millprocess. The main attention in this thesis is paid to the blastfurnace process, which is powered by a line-operatedsynchronous machine.

    The thesis shows that the protection equipment forelectrical machines can be adjusted to avoid unnecessaryshutdowns. It is also explained why there are high torque andcurrents during voltage sags as well as after voltage sags. Itis shown that the first peak torque and current during thevoltage sags is almost proportional to the voltage change, thatis the voltage magnitude before the voltage sag minus thevoltage magnitude during the voltage sag. The first peak torqueand current after the voltage sag depends sinusoidal-like onthe duration of the voltage sag and almost proportional to thevoltage change during the voltage sag. There is no fluxsaturation during voltage sags, however after voltage sagssaturation is very likely to occur. The thesis explains why andalso how the flux is changed during and after voltage sags.

    The duration of voltage sags is in many cases set by theprotection equipment located in switchyards. It is shown thatthe durations of voltage sags can be changed to durations thatwill cause less peak torque and current after voltage sags forline-operated AC-machines. It is also shown how this istheoretically achieved.

    Keywords:Rolling mill, Blast furnace, Power Quality,Synchronous machine, Asynchronous machine, Voltage sag, Voltageinterruption, Ride-through, Process disturbances, Simulation,Modelling

  • 26.
    Chin, Yung-Kang
    KTH, Tidigare Institutioner, Elektrotekniska system.
    A permanent magnet synchronous motor for an electric vehicle - design analysis2004Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents the study and the design analysis of apermanent magnet synchronous motor (PMSM) for the tractionapplication of an electric vehicle. An existing inductiontraction motor for an electric forklift benchmarks the expectedperformances of the proposed PMSM design. Further, thepossibility of using the identical stator as the one used inthe induction motor is explored for the fast prototyping. Theprototype motor is expected to be field-weakened and to have aconstant power speed range (CPSR) of 2.5 to 3.

    A design approach based on the CPSR contour plot in aninterior permanent magnet (IPM) parameter plane is derived toobtain the possible designs that meet all the designspecifications and the targeted CPSR. This study provides thepossible alternative designs for the subsequent futureprototype motors.

    An analytical approach to estimate the iron loss in PMsynchronous machines is developed and included in the designprocedure. The proposed technique is based on predicting theflux density waveforms in the various regions of the machine.The model can be applied at any specified load condition,including the field-weakening operation region. This model canbe ultimately embedded in the design process for a routine usein loss estimations.

    The first prototype motor with an inset permanent magnetrotor has been built and the available measurements are used tovalidate the design performance. In particular, the thermalanalyses based both on the lumped-circuit approach and thenumerical method are compared with the measured results. Asecond and possibly a third prototype motor targeting a widerand higher performance will be carried out in the continuingphase of the project.

    Keywords:Constant Power Speed Range, Electric Vehicles,Field-weakening, Reference Flux Linkage, Iron Loss, PermanentMagnet Synchronous Motor, Thermal Analysis

  • 27.
    Chin, Yung-Kang Robert
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Nordlund, E
    Staton, A
    Thermal analysis - Lumped-circuit model and finite element analysis2003Inngår i: IPEC 2003: Proceedings of the 6th International Power Engineering Conference, SINGAPORE: NANYANG TECHNOLOGICAL UNIV , 2003, s. 952-957Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents the thermal analysis of Permanent Magnet Synchronous Motors (PMSMs) for electric vehicle traction applications. Modem thermal design techniques can be classified into two general methods, analytical lumped circuit and numerical analysis. It is the aim of this paper to investigate the strengths and weaknesses of the two approaches. Two commercially available thermal design packages, Motor-CAD and FEMLAB, are used in our investigation. Motor-CAD is a 3-dimensional (3-D) lumped circuit analysis package dedicated to the thermal design of motors. FEMLAB is a multi-physics 2- and 3-dimensional finite element analysis (FEA) package.

  • 28.
    Chin, Yung-Kang Robert
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Soulard, Juliette
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    A permanent magnet synchronous motor for traction applications of electric vehicles2003Inngår i: IEEE IEMDC'03: IEEE INTERNATIONAL ELECTRIC MACHINES AND DRIVES CONFERENCE, VOLS 1-3, NEW YORK: IEEE , 2003, s. 1035-1041Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents the design of a Permanent Magnet Synchronous Motor (PMSM) for traction applications of electric vehicles (EVs). The design is based on the stator geometry of an existing commercial available induction traction motor. The rotor configurations considered in this study are the surface mounted. magnet (SPM) and the inset permanent magnet (IPM) types. Both designs are investigated for the identical specification and their overall performances are-compared with the existing asynchronous motors. A schematic block diagram of the design flow chart applied is Illustrated. An analytical approach for calculating stator iron loss [1] is applied in the design procedure to ensure the required performance is reached. A thermal analysis of the prototype motor based on the lumped-circuit model and finite element analysis is also presented. Lastly, conclusions on the overall performance of. PMSMs for electric vehicle applications are made and discussed.

  • 29.
    Chin, Yung-Kang Robert
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Soulard, Juliette
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    A theoretical study on permanent magnet synchronous motors for electric vehicles2003Inngår i: IPEC 2003: PROCEEDINGS OF THE 6TH INTERNATIONAL POWER ENGINEERING CONFERENCE, SINGAPORE: NANYANG TECHNOLOGICAL UNIV , 2003, s. 435-440Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the theoretical design of a conventional radial flux permanent magnet synchronous motor (PMSM) with field-weakening capability for electric vehicles. The study applies to both surface mounted and inset magnet rotor configurations. Various losses estimations are embedded into the design procedures to ensure that the desired overall drive performance is achieved. Influences of parameters such as air gap size and magnet thickness on the performances are studied. Back EMF and cogging torque are also investigated and analysed by using both the Finite Element Method (FEM) and an analytical approach. Design examples of various PMSMs with a given stator geometry are presented.

  • 30.
    Chin, Yung-Kang Robert
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Soulard, Juliette
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Modeling of iron losses in permanent magnet synchronous motors with field-weakening capability for electric vehicles2003Inngår i: International Journal of Automotive Technology, ISSN 1229-9138, E-ISSN 1976-3832, Vol. 4, nr 2, s. 87-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent advancements of permanent magnet (PM) materials and solid-state devices have contributed to a substantial performance improvement of permanent magnet machines. Owing to the rare-earth PMs, these motors have higher efficiency, power factor, output power per mass and volume, and better dynamic performance than induction motors without sacrificing reliability. Not surprisingly, they are continuously receiving serious considerations for a variety of automotive and propulsion applications. An electric vehicle (EV) requires a high-efficient propulsion system having a wide operating range and A capability of generating a high peak torque for short durations. ne improvement of torque-speed performance for these systems is consequently very important, and researches in various aspects are therefore being actively pursued. A great emphasis has been placed on the efficiency and optimal utilization of PM machines. This requires attention to many aspects related to the machine design and overall performance. In this respect, the prediction of iron losses is particularly indispensable and challenging, especially for drives with a deep field-weakening range. The objective of this paper is to present iron loss estimations of a PM motor over a wide speed range. As aforementioned, in EV applications core losses can be significant during high-speed operation and it is imperative to evaluate these losses accurately and take them into consideration during the motor design stage. In this investigation, the losses are predicted by using an analytical model and a 2D time-stepped finite element method (FEM). The results from different analytical approaches are compared with the FEM computations. The validity of each model is then evaluated by these comparisons.

  • 31.
    Cirani, Maddalena
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Analysis of an innovative design of an axial flux Torus-machine2002Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The high compactness of axialflux permanent magnet (AFPM) machines compared with theconventional induction, DC and radial flux permanent magnet(RFPM) machines, renders this machine-topology particularlysuitable to be integrated in a system for hybrid electricvehicles (HEVs). Indeed, due to the limited space inside thevehicle, the considerable reduction in volume and weightoffered by AFPM machines is of major importance. In particular,the limited axial length of AFPM machines is an important issuefor HEVs. Furthermore, AFPM machines present high efficiencydue to the absence of rotor currents. However, in order to besuitable for traction applications, the AFPM machine has tooperate at high-torque and high-speeds.

    A particular type of AFPMmachine, the so-called Torus-machine, has been investigated andan innovative design has been analyzed in order to fulfill thehigh-speed requirements. In fact, the machine has been designedto work in field-weakening operations and, to this purpose, themachine stator is provided with teeth and slots so as toincrease the field-weakening capability. A further improvementof the field weakening capability of the machine is obtained bythe addition of rotor saliency.

    A general analysis of theequations, which describe the machine parameters, is presented.Next the design of a 30kW, 4000 r/min Torus-machine has beeninvestigated on the basis of volume and performancerequirements. Furthermore, the performance of a machine havingthe previously calculated parameters but without rotor saliencyhas been investigated and the results have been compared. FEMcalculations based on the software programs Flux-2D and Flux-3Dhave been examined and most of the results present satisfactoryagreement with the analytical calculations. Moreover, asimplified thermal model of the machine has been developed inorder to predict the temperature rise in the winding atdifferent operating conditions.

    ABB Corporate Research,Västerås, Sweden, has manufactured a prototype of themachine. The measurements performed on the parameters of theprototype validate the analytical results. Furthermore, themachine thermal test agrees satisfactorily with the thermalmodel for the no load condition.

  • 32.
    Cosic, Alija
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Lindbäck, Jens
    Arshad, Waqas Mahmood
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Leksell, Mats
    KTH, Skolan för elektro- och systemteknik (EES).
    Thelin, Peter
    Nordlund, Erik
    APPLICATION OF A FREE-PISTON GENERATOR IN A SERIES HYBRID VEHICLE2003Inngår i: Proceedings of the 4th international Symposium on Linear Drives for Industry Applications, 2003, s. 541-544Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper deals with an investigation of differentcontrol strategies for a series hybrid electric vehicle (SHEV).Another discussed issue is the application of a free-pistongenerator. By replacing a conventional combustion enginewith a free-piston generator it is possible to increase the totalefficiency of the system. The object of investigation is a12-ton truck, mainly used in urban areas. The drive systemhas been built up and simulated in a MATLAB Simulinkenvironment. It follows from the investigation that theapplication of a free-piston engine in a SEHV can increasethe efficiency by 25 percent compared to the conventionalengine.

  • 33.
    Demetriades, Georgios D.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Evaluation of different topologies for high-power dc-dc converters2001Licentiatavhandling, monografi (Annet vitenskapelig)
  • 34.
    Demetriades, Georgios
    et al.
    ABB Environmental Systems.
    Ranstad, Per
    ABB Environmental Systems.
    Sadarangari, C.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Three elements resonant converter: The LCC topology by using MATLAB2000Inngår i: PESC Record: IEEE Annual Power Electronics Specialists Conference, Galway, UK, 2000, Vol. 2, nr Piscataway, NJ, United States, s. 1077-1083Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The behaviour of a series-parallel resonant power converter is analysed by means of MATLAB simulations. PSPICE and experimental results are also presented. Stress parameters are calculated and compared with those of the series-loaded resonant power converter.

  • 35.
    Dubickas, Valentinas
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Edin, Hans
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Couplers for on-line Time Domain Reflectometry diagnostics of power cables2004Inngår i: 2004 ANNUAL REPORT CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA, 2004, s. 210-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates three types ofcouplers for sending and receiving a Time DomainReflectometry (TDR) signal to and from a cable on-line.Transfer functions of the couplers were estimated andlumped element models were built. The couplers wereplaced on a power cable with High Voltage (HV)terminations. Measurements were performed at a HVsimulating realistic conditions. In this cable weinvestigated voltage pulse injection, propagation, anddetection for different coupler topologies and HVterminations.

  • 36.
    Edin, Hans
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Partial Discharges Studied with Variable Frequency of the Applied Voltage2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis concerns partial discharge (PD) diagnostics withvariable frequency of applied voltage in the frequency range 1mHz - 400 Hz. The exploration of a new type of spectroscopythat combines partial discharge analysis and dielectricresponse is demonstrated. A question addressed is if and howthe PD activity varies with the frequency of the appliedvoltage. The nature of an existing frequency dependence couldbe useful in the classification of different defects and tojudge the degree of progressive ageing.

    A Variable-Frequency Phase Resolved Partial DischargeAnalysis (VF-PRPDA) technique is developed for the appliedvoltage frequency range 1 mHz - 400 Hz. The VF-PRPDA techniqueis combined with a system for high voltage dielectricspectroscopy that allows simultaneous measurements. TheVF-PRPDA technique is used for studying the frequencydependence of PD. The PD activity is for example measured byintegrated measures like total charge per cycle and totalnumber of discharges per cycle. Statistical measures like mean,standard deviation, skewness, kurtosis etc. are applied tomeasure the frequency dependence of the phasedistributions.

    High voltage dielectric spectroscopy is supplemented withharmonic analysis for studying non-linear dielectric responsecurrents.

    The VF-PRPDA technique is demonstrated on defined objectslike point-plane gaps and artificial voids, but also on aninsulated stator bar and a paper insulated cable. Surfacedischarges on insulating surfaces are studied in an environmentwith a controlled relative humidity and temperature. Theadsorption of moisture on the insulating surface alters thesurface conductivity of the surface and the frequencydependence of the PD activity.

    The influence of temperature upon the PD activity is studiedfor a oil paper insulated cable.

    The results of the measurements show that the partialdischarge activity in general is frequency dependent over thefrequency range 1 mHz - 400 Hz. The reasons behind thefrequency dependence are linked to surface- and bulk-conducting mechanisms, frequency dependent field distributionsand statistical effects of the supply of start electrons.

    An algorithm is developed that relates the phase resolved PDcurrent measured with the PRPDA technique to the non-linearcurrent measured with dielectric spectroscopy. The algorithm isexperimentally verified by simultaneous measurements of PRPDAand dielectric spectroscopy on defined objects. The resultsexplain the contribution of PD to the apparent capacitance andloss. Moreover, the harmonics of the fundamental currentcomponent yield information about, for example, polaritydependent discharge sources.

    Keywords:diagnostic methods, partial discharges, phaseresolved, variable frequency, dielectric spectroscopy,dielectric response, harmonics, insulation

  • 37.
    Edin, Hans
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    the influence of dielectric polarisation on the measured pd charge in a two-layer dielectric system1999Inngår i: Proceedings of Nordic Insulation Symposium, 1999, s. 433-441Konferansepaper (Annet vitenskapelig)
  • 38.
    Edin, Hans
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Forssén, Cecilia
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Variable frequency partial discharge analysis of in-service aged machine insulation2003Inngår i: Proceedings Nordic Insulation Symposium, 2003, s. 29-35Konferansepaper (Fagfellevurdert)
  • 39.
    Edin, Hans
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Gäfvert, Uno
    harmonic content in partial discharge current measured with dielectric spectroscopy1998Inngår i: Annual report. 1998, 1998Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Phase resolved partial discharge analysis and dielectricspcctroscopy measurements have been performed at50Hz and variable voltage on two artificial defects thathave different average charge phase distributions. Influenceof partial discharges on permittivity and loss-factoris dcduced to the phase position of the partial dischargeactivity. Symmetry properties between positive andnegative charge distributions have been related to theharmonic content of the partial discharge current.

  • 40.
    Edin, Hans
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Gäfvert, Uno
    Simultaneous measurement of phase resolved partial discharges and dielectric spectroscopyInngår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135Artikkel i tidsskrift (Annet vitenskapelig)
  • 41.
    Edin, Hans
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Jayaram, Shesha
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Gäfvert, Uno
    influence of relative humidity on surface discharge over the frequency range 01 hz to 100 hzInngår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135Artikkel i tidsskrift (Annet vitenskapelig)
  • 42.
    Ekstedt, Mathias
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Enterprise architecture for IT management: a CIO decision making perspective on the electrical power industry2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Within the electric power industry, the average company's enterprise system - i.e. the overall system of IT related entities - is today highly complex. Technically, large organizations posses hundreds or thousands of extensively interconnected and heterogeneous single IT systems performing tasks that varies from enterprise resource planning to real-time control and monitoring of industrial processes. Moreover are these systems storing a wide variety of sometimes redundant data, and typically they are deployed on several different platforms. IT does, however, not execute in splendid isolation. Organizationally, the enterprise system embraces business processes and business units using as well as maintaining and acquiring the IT systems. The interplay between the organization and the IT systems are further determined by for instance business goals, ownership and governance structures, strategies, individual system users, documentation, and cost.

    Lately, Enterprise Architecture (EA) has evolved with the mission to take a holistic approach to managing the above depicted enterprise system. The discipline's presumption is that architectural models are the key to succeed in understanding and administrating enterprise systems. Compared to many other engineering disciplines, EA is quite immature in many respects. This thesis identifies and elaborates on some important aspects that to date have been overlooked to a large extent. Firstly, the lack of explicit purpose for architectural models is identified. The thesis argues that the concerns of a company's Chief Information Officer (CIO) should guide the rationale behind the development of EA models. In particular, distribution of IT related information and knowledge throughout the organization is emphasized as an important concern uncared for. Secondly, the lack of architectural theory is recognized. The thesis provides examples of how theory, or analysis procedures, could be incorporated into the Enterprise Architecture approach and hereby concretely drive the development of the architectural models. Due to the nature of enterprise systems, EA theories inevitable will be of an indicative character. Finally, in relation to the models as such, three aspects are highlighted. Firstly, the cost of collecting information from the organization to populate models is routinely neglected by the EA community. This expense should be evaluated in relation to the utility of analyses that the information can provide in terms of better informed decision making by the CIO. Secondly, models (and meta-models) must be kept consistent. And thirdly, the design of models is restricted by the limited mental capabilities of the minds of the model users. CIO concerns must consequently be easy to extract from the Enterprise Architecture models.

    Key words: Enterprise Architecture, Enterprise System, Chief Information Officer (CIO), Information Technology (IT) Management, Architectural Theory, Electric Power Industry

  • 43.
    Ekstedt, Mathias
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Johnson, Pontus
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Exploring architectural analysis credibility from a developer perspective2002Inngår i: Proceedings of the Fourth Australian Workshop on Software and Systems Architecture, 2002Konferansepaper (Fagfellevurdert)
  • 44.
    Ekstedt, Mathias
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Johnson, Pontus
    Lilliesköld, Joakim
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Jonsson, Narcisa
    Making project complexity understandable: the elegance of notations2003Inngår i: Proceedings of the 12th International Conference on Management of Technology (IA-MOT), Nancy, France, 2003.: From Information to Knowledge to Competencies: Key Success Factors for Innovation and Sustainable Development. / [ed] Hosni, Y.A., Khalil, T.M., Morel-Guimaraes L., 2003Konferansepaper (Annet vitenskapelig)
  • 45.
    Ekstedt, Mathias
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Johnson, Pontus
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Lindström, Åsa
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Johansson, Erik
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Nordström, Lars
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Management of Enterprise Software System Architectures: Focusing on Information Economy and Model Consistency2003Inngår i: Proceedings of the 3rd Conference on Software Engineering Research and Practice in Sweden, 2003Konferansepaper (Fagfellevurdert)
  • 46.
    Ekstedt, Mathias
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Johnson, Pontus
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Sjölin, Peter
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Lilliesköld, Joakim
    KTH, Tidigare Institutioner, Elektrotekniska system.
    The architectural information view for the power electricity industry2003Inngår i: Proceedings of the CIGRE SC D2´s Colloquium, 2003Konferansepaper (Fagfellevurdert)
  • 47. Endrenyi, J.
    et al.
    Anders, G. J.
    Bertling, Lina
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Kalinowski, B.
    Comparison of two methods for evaluating the effects of maintenance on component and system reliability2004Inngår i: 2004 International Conference on Probabilistic Methods Applied to Power Systems, 2004, s. 307-312Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Two recently proposed methods for evaluating the effects of various maintenance policies on the reliability and operating costs of electric power systems are compared. Both programs, the one developed in Canada and the other in Sweden, first generate a priority list of components whose failures have the highest effect on system reliability, then examine the failure rates of the components on the top of the list when various maintenance policies are applied. Finally, reliability indices for the whole system are computed with the critical components represented by the failure rates corresponding to the various policies. This way, maintenance policies can be selected either to achieve the highest system reliability or the lowest operating costs. The approach is illustrated in a numerical example where both the similarities of, and the differences between, the two methods can be recognized. Comments are made on the reasons for the differences.

  • 48.
    Engdahl, Göran
    et al.
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    Krah, J. H.
    The feasibility to model a 3-leg core type medium frequency power transformer by use of a dual Cauer circuit2002Inngår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 242, s. 1210-1213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model for medium frequency power transformers is suggested, The model is able to treat arbitrary topologies by use of Cauer circuits for core and windings. An implementation example is given for a 1-phase transformer with turn ratio 1:1. The model can be extended to include winding insulation materials by use of lumped capacitive and resistive circuit elements.

  • 49.
    Engström, Jörgen
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Analysis and Verification of a Slotless Permanent Magnet Motor for High Speed Applications2001Doktoravhandling, monografi (Annet vitenskapelig)
  • 50.
    Eriksson, Mikael
    KTH, Tidigare Institutioner                               , Elektrotekniska system.
    How to formulate a strategy when procuring a large technical complex system2003Inngår i: IAMOT 2003: 12th International Conference on Management of Technology, Nancy, France, May 13-15, 2003, 2003Konferansepaper (Annet vitenskapelig)
12345 1 - 50 of 233
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