Gubici uslijed vrtložnih struja u jezgri transformatora

master's thesis

• Title (english): Eddy Current Losses in Transformer Core
• Author: Zvonimir Jurković
• Mentor: Željko Štih (mentor)
• Committee member: Željko Štih (predsjednik povjerenstva)
• Committee member: Bojan Trkulja (član povjerenstva)
• Committee member: Tomislav Župan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2020-07-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

U ovom diplomskom radu, razrađen je postupak za proračun gubitaka vrtložnih
struja u prvim paketima jezgre transformatora, pri čemu je korištena metoda konačnih
elemenata (FEM - eng. Finite Element Method). Iako je za većinu gubitaka u jezgri
zaslužan glavni magnetski tok, u ovom slučaju razmatrani su gubici vrtložnih struja
uzrokovani rasipnim magnetskim poljem.
Kada se metoda konačnih elemenata koristi za rješavanje problema, koji uključuju
lamelirane materijale, pri proračunu je potrebno koristiti mrežu sa jako velikim brojem
elemenata. Čak i uz današnja moćna računala, takav 3D FEM proračun bi trajao jako
dugo, što ga čini nepraktičnim. Prikladnije rješenje, u smislu brzine izvođenja, bi
bio 2D FEM proračun, ali nedostatak je to što se 2D modelima ne može vjerodostojno
opisati geometrija zadanog problema. Stoga je cilj ovog rada doći do rješenja problema
2D modeliranjem, a da se pritom ne gubi na točnosti rezultata.
Za razmatrane gubitke zaslužan je rasipni magnetski tok koji ulazi okomito u površinu
prvog paketa. Za početak je potrebno dobiti raspodjelu normalne komponente
magnetske indukcije po površini paketa. U tu svrhu, osim FEM-a, koristi se i Rabinsova
metoda. Nakon što se dobije raspodjela magnetske indukcije po paketu, slijedi
proračun gubitaka. Za taj proračun koristi se model za gubitke, koji raspodjelu indukcije
koristi kao ulazni parametar. Konačan rezultat je raspodjela gubitaka u prvom
paketu. Za FEM proračune koristi se programski paket Infolytica MagNet, dok se za
analitički proračun Rabinsovom metodom koristi MATLAB.
Nakon što je razrađen čitav postupak, izrađena je i aplikacija za proračun gubitaka
temeljena na njemu. Za izradu aplikacije korišten je programski paket MATLAB, dok
aplikacija za FEM proračune koristi open-source programski paket FEMM.

Abstract (english)

In this master’s thesis, a method for the calculation of eddy current losses in the
outer packages of the transformer core is developed, using the finite element method.
Although the main magnetic flux is responsible for most of the core losses, in this case
the losses caused by stray flux are considered.
Solving problems that involve laminated steel plates, with finite element method,
requires a grid with large number of elements. 3D FEM calculation would take much
time, making it impractical. A more suitable solution, in terms of execution speed,
would be 2D FEM calculation, but the disadvantage is that 2D models cannot reliably
describe the geometry of a given problem. Therefore, the aim of this paper is to find a
way to solve the problem by 2D modeling, without losing the accuracy of the results.
The considered losses are caused by perpendicular stray flux that enters outer packages.
To begin with, it is necessary to obtain the distribution of the magnetic field
over the surface of the outer package. In addition to FEM, Rabins’ method is used for
this purpose. After the distribution of the magnetic field is obtained, the calculation of
the losses follows. A loss model is used for this calculation, which uses the magnetic
field distribution as an input parameter. The final result is the distribution of losses in
the first package. Infolytica MagNet software package is used for FEM calculations,
while MATLAB is used for analytical calculation using the Rabins’ method.
After the method was developed, an application for loss calculation, based on it,
was created. MATLAB software package was used to create the application, while the
FEM calculations were performed by open-source FEMM software package.

• Keywords: Metoda konačnih elemenata; Rabinsova metoda; gubici rasipnog magnetskog polja; gubici u lameliranim materijalima
• Keywords (english): Finite element method; Rabins' method; stray losses; losses in laminated materials
• Language: croatian
• URN:NBN: urn:nbn:hr:168:375691
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-01-13 10:08:35