Thesis Type: Doctorate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2016
Student: SELAMİ BALCI
Supervisor: İBRAHİM SEFAAbstract:
There have been many developments offering different options for the production technology of high-frequency core materials in the past decade. In many different areas which include power electronics converter topologies like electric transportation industry, the medium frequency power transformers began to be seen as a result of these developments. In high-power static power conversion, there are studies usually used the switching values called as medium frequency region between 400 Hz and 20 kHz. The range of the switching frequency varies depending on the operating limits of all active and passive components in the topology. Also, in determining the switching frequency of the converter, the predetermination of the losses and thermal behaviors in the related frequency values of the power transformers, which will operate with the appropriate power switch to modern technology, have great importance in the design phase. Ferrite cores, which were an important option for high frequency designs in the past years, have brought great sizing limitation for the transformers because of being not produced in great sizes. Therefore, researchers have focused upon the core structures which can be realized with the soft magnetic materials such as amorphous and nanocrystalline structures for smaller and more efficient transformer design. In this study, medium frequency power transformer was designed with nanocrystalline core material by usage of the electromagnetic and power electronics softwares. In the design process, the transformer was primarily modeled with a three dimensional finite element method, and then this magnetic circuit model was co-simulated in realistic conditions with the power electronics software. Thus, the prototype product was obtained with the nanocrystalline core material and aluminum foil windings. Then, this prototype was tested in the experimental setup of a single phase full bridge inverter circuit so that the efficiency and the temperature increase values were determined. The experimental results of the developed medium frequency power transformer were seen to be compatible with the values of the simulation.