研究目的
Investigating the origins of acoustic noise emitted by a power transformer core and ways of controlling it, focusing on the magnetic core vibration during the magnetizing process as the primary source of noise.
研究成果
The study concludes that high localized vibration does not necessarily cause high noise due to phase differences in surface vibrations. It also shows that the A-weighted noise of a three-phase core can be less than that of an equivalent single-phase core. The research highlights the complex relationship between magnetostriction, electromagnetic forces, and acoustic noise in transformer cores, suggesting that more knowledge of the actual stress distribution within cores is needed to better understand and control noise.
研究不足
The study acknowledges the difficulty in determining the proportions of localized vibration due to magnetostrictive or electromagnetic forces, as at any position, one may dominate or they can be of the same order of magnitude. Additionally, the study is based on model transformer cores, which may not fully represent commercial transformer cores.
1：Experimental Design and Method Selection:
Magnetostriction of grain-oriented 3% SiFe sheets was measured before assembly into model transformer cores. Core vibration was measured using a laser scanning vibrometer, and harmonic spectra of acoustic noise were evaluated from microphone outputs.
2：Sample Selection and Data Sources:
Commercial grades of 0.30 mm thick CGO, HGO, and LDR were selected for the study.
3：30 mm thick CGO, HGO, and LDR were selected for the study.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A Polytec PSV-400 scanning vibrometer, an array of eight B&K 4188-A-021 condenser microphones, and a three-phase autotransformer were used.
4：Experimental Procedures and Operational Workflow:
The transformer under test was placed in a hemi-anechoic acoustic chamber. Vibration and noise measurements were conducted under controlled conditions.
5：Data Analysis Methods:
Measurement data were analyzed using LabVIEW and MATLAB, focusing on the relationship between vibration harmonics profiles and A-weighted acoustic noise spectra.
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