Investigation Of Vibration Effects Caused By Harmonics Medium Frequency Nanocrystalline Core Power Transformers

Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2019


Supervisor: İBRAHİM SEFA


In this study the vibrations of two medium frequency transformers with the same power value using nanocrystalline and 6.5% SiFe core materials were investigated. First, electromagnetic analyzes were performed at 50Hz, 400Hz and 10kHz operating frequencies under sinusoidal and square wave excitation modes. In these analyzes, the vibration of the core material was determined under the no-load operation, and then the effects of different loading levels on these vibrations were determined. In electromagnetic analyzes, core flux density and core force distributions were determined for each operating case. Then, harmonic response analyzes were performed to determine the vibration acceleration. The acceleration harmonic components of the nanocrystalline core were found to be smaller than 6.5% SiFe core under medium frequency operation. Although the increase in the loading level led to a greater increase in the acceleration harmonic amplitudes of the nanocrystalline core, the acceleration harmonic amplitudes of the 6.5% SiFe core remained higher. The acceleration harmonic amplitudes obtained in sinusoidal excitation for both cores were lower than the square wave excitation. The acceleration harmonic spectrum obtained under 50Hz operation was found to be much smoother than the acceleration harmonic spectrum at medium frequency, especially for 6,5% SiFe core.