doktorska disertacija
Martin Petrun (Author), Drago Dolinar (Mentor)

Abstract

Doktorska disertacija obravnava različne metode modeliranja, analizo ter načine preprečevanja pojavov neuravnoteženega in nehomogeno porazdeljenega magnetnega pretoka v magnetnih komponentah močnostnih DC DC pretvornikov. V okviru disertacije sta predstavljeni dve metodi podrobnejšega modeliranja magnetnih komponent. Prva metoda predstavlja uporabo metode končnih elementov, kjer je model končnih elementov povezan z veznim modelom DC-DC-pretvornika, v katerem so ustrezno upoštevane lastnosti aktivnih in pasivnih komponent pretvornika. Podrobneje sta predstavljena teoretično ozadje in način vzpostavitve neposredne povezave na osnovi modificirane metode vozliščnih potencialov. Druga metoda za podrobnejše modeliranje magnetnih komponent predstavlja uporabo metode koncentriranih parametrov. S pomočjo te metode je na podlagi reluktančnih vezij upoštevana topologija magnetnega podsistema. Z uporabo ustreznih histereznih modelov so v reluktančnem modelu upoštevane histerezne lastnosti uporabljenega materiala. Predstavljen je tudi dinamičen model mehkomagnetne pločevine, ki upošteva vpliv induciranih vrtinčnih tokov na porazdelitev magnetnega polja znotraj mehkomagnetne pločevine. Prav tako je predstavljena metoda za določitev težko določljivih parametrov veznih modelov, ki temelji na uporabi optimizacijskega algoritma diferenčne evolucije. Nadalje so predstavljeni in analizirani vzroki za pojav neuravnoteženega in nehomogeno porazdeljenega magnetnega pretoka v jedrih transformatorjev močnostnih DC DC pretvornikov. Neuravnoteženi magnetni pretok je posledica pojava lezenja oziroma enosmerne komponente magnetnega pretoka v jedru transformatorja. Nehomogeno porazdeljen magnetni pretok pa je posledica neustrezne razporeditve navitij na jedru transformatorja, ki povzroči neuravnotežene delne magnetne sklepe v oknu transformatorja. Oba opisana pojava lahko povzročita nasičenje jeder transformatorjev, v splošnem pa znižujeta izkoristek, gostoto moči in zanesljivost delovanja naprave. Nadalje so predstavljeni tako aktivni kot tudi pasivni ukrepi za preprečevanje opisanih pojavov. Ugotovljeno je, da lahko neuravnoteženost magnetnega pretoka preprečujemo tako z aktivnimi kot tudi pasivnimi ukrepi, v nasprotju s tem pa lahko nehomogeno porazdelitev magnetnega pretoka zmanjšujemo samo s pasivnimi ukrepi. Predstavljeni so tudi načini in senzorji za ugotavljanje neuravnoteženosti magnetnega pretoka in nasičenja jeder magnetnih komponent, kjer je podrobneje predstavljen senzor v obliki magnetnega mostiča. S pomočjo tega senzorja je načrtovana aktivna metoda za preprečevanje nasičenja v jedrih transformatorjev, ki temelji na histerezni regulaciji magnetnega pretoka. Na koncu je obravnavana problematika analizirana s pomočjo numeričnih izračunov na podlagi izpeljanih modelov, ki so potrjeni tudi eksperimentalno.

Keywords

histerezni pojavi;magnetne komponente;metoda končnih elementov;močnostni DC-DC pretvorniki;modeliranje;nehomogeno porazdeljen magnetni pretok;neuravnotežen magnetni pretok;preprečevanje nasičenja;vezni modeli;vrtinčni toki;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UM FERI - Faculty of Electrical Engineering and Computer Science
Publisher: [M. Petrun]
UDC: 621.317.43:537.626(043.3)
COBISS: 18058518 Link will open in a new window
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Other data

Secondary language: English
Secondary title: All-fiber thermo-opticsʼ devices based on the vanadium doped fibers
Secondary abstract: This thesis describes various modeling techniques, analyses and prevention methods for imbalanced and inhomogeneous distribution of magnetic flux inside the magnetic components of high power DC-DC converters. Two techniques for detailed modeling of the discussed magnetic components are presented in detail. In the first technique the finite element method is used, where the detailed finite element model is adequately coupled with the circuit model of the DC DC converter, and where also the properties of active and passive converter components are described adequately. The direct coupling between both models based on modified nodal analysis is presented. The second technique for detailed modeling of magnetic components is based on the lumped parameter method. This way the topological as well as hysteresis properties of the magnetic subsystem are taken into account. Further, a magneto-dynamic model of soft magnetic steel sheets is presented, where the interdependence between eddy currents and magnetic field inside soft magnetic steel sheets is taken into account. The parameters of circuit models that are difficult to determine, are determined using optimization algorithm differential evolution. This thesis also presents overviews and analyses of sources regarding imbalanced and inhomogeneous distribution of magnetic flux inside the magnetic cores of transformers inside DC-DC converters. An imbalanced magnetic field is a consequence of the drift of the magnetic flux inside the transformer core. Inhomogeneous distribution of magnetic field is however a consequence of inadequate distribution of transformer windings along the transformer's magnetic core. These discussed phenomena can cause both saturation of the transformer core, and generally leads to lower efficiencies, power densities and operating reliabilities of such devices. Further, active and passive methods for prevention of the discussed phenomena are presented in detail. It is recognized that the imbalance of the magnetic flux can be prevented both with active as well as passive methods, where inhomogeneous distribution of magnetic flux can be reduced only by passive measures. Methods and sensors for determining magnetic flux imbalances and saturation inside the magnetic components are also presented, where the sensor in the form of a magnetic bridge is presented in detail. Based on this sensor an active technique for preventing of saturation of transformers' cores is presented, which uses hysteresis control of magnetic flux inside the transformer core. At the end of the thesis the discussed problems are analysed with the numerical calculations based on the derived models, which are validated with measurements.
Secondary keywords: high power DC-DC coverters;high power density;eddy currents;finite element method;hysteresis;imbalanced magnetic flux;inhomogenous magnetic flux distribution;lumped element model;magnetic components;modeling;saturation prevention;Optična vlakna;Disertacije;Funkcionalna raba;
URN: URN:SI:UM:
Type (COBISS): Doctoral dissertation
Thesis comment: Univ. v Mariboru, Fak. za elektrotehniko, računalništvo in informatiko
Pages: XXVI, 199 str.
ID: 8730291