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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Control Systems for Experimental Magnetic Materials Characterization Using Dynamic Preisach Models / Reglering av mätsystem för magnetisk material egenskaper med dynamiska Preisach modellen

MEHRPARVAR, MAHSHID January 2014 (has links)
The eciency of electrical machines is of major concern due to their widespread usage and the globally increasing awareness of energy consumption issues. Iron losses have a signicant impact on the total and thus researchers and manufacturers of electrical machines are developing dierent strategies in order to reduce them. The iron losses are highly dependent on the magnetic material that is used and thus it is necessary to identify its relevant characteristics. In this work, the development of a control system for inducing a pure sinusoidal magnetic ux density in the magnetic material is described. This is necessary in order to perform characterisation of the magnetic material. The main diculty is the highly non-linear and hysteretic relationship between the magnetic eld strength and the magnetic ux density. In order to mitigate the eect of the hysteresis, a mathematical inverse model was used in the control system. To nd a suitable model, an extensive study of literature was performed and discussed in this work. The Preisach model and its dynamic extension was chosen as the most suitable approach. A detailed description of both theory and implementation details is provided in this work. Furthermore, the model is validated by comparing simulation against measurement data for two dierent materials. In the last part of this work, the inverse model is combined with a controller to form a feedback control system. Two dierent control schemes are investigated: a simpler PI controller and a more elaborate disturbance observer (DOB) based control scheme. The DOB is used to observe the hysteresis inversion error and the observation is used to correct for the error. The controller's ability to produce a pure sinusoidal magnetic ux density was assessed by simulations with dierent magnetic materials at varying frequencies. / Verkningsgraden for elmotorer ar av okande intresse pa grund av deras omfattande anvandning och vaxande oro for globala energiforbrukningsfragor. Jarnforluster har ett stort inytande i de totala forlusterna och ar darfor ett viktigt omrade for forskare och tillverkare av elektriska motorer. Jarnforlusterna beror till stor del av det magnetiska materialet som anvands i konstruktion av elmotorer och det ar darfor nodvandigt att identiera materialets egenskaper. I det har arbetet beskrivs utvecklingen av ett reglersystem for att inducera en ren sinusformat magnetisk odestathet i ett magnetiskt material. Detta ar nodvandigt for att kunna bestamma det magnetiska materialets egenskaper under kontrollerade forhallanden. Huvudsvarigheten ar det icke-linjara sambandet mellan magnetiska faltstyrkan och odest atheten. Sambandet formar en hysteres och for att eliminera dess inytande anvandes en matematisk invers model. For att hitta en lamplig model genomfordes en literaturstudie och Preisach modellen och dess dynamiska utokning valdes. I detta arbete nns en detaljerad beskrivning av bade teorin bakom modellen och dess implementering. Modellen utvarderades genom att jamfora matvarden med simulationsresultat for olika magnetiska material. I sista delen av detta arbete kombineras inversmodellen med ett reglerssystem for att kunna uppna en sinusformat odestathet i det magnetiska materialet. Tva olika regleralgoritmer utvarderas, en enklare PI-regulator och en regulator som inkluderar en sa kallat "Disturbance Observer" (DOB). DOB:n anvandes for att observera felet som uppstar vid invertering av hysteresen och for att korrigera felet. De bada regulatorernas formaga attaterskapa en ren sinusformat magnetisk odestathet testas genom att genomfora simulationer for olika magnetiska material vid varierande frekvenser.

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