Experimental identification on natural frequency of lamination steel plate using multi-objective optimizing method

Abstract

For the transformer which is general industrial apparatus, electromagnetic noise and earthquake resistance are also important functions. Especially electromagnetic noise serves as an environmental load, so noise control is called for. In a transformer, at the time of operation, electromagnetism vibration is added to the iron core which is the main part, and electromagnetic noise occurs. First of all, an iron core stacks a thin electromagnetic steel sheet, and is being fixed with bolts. Therefore, when a fastening position and forces are not suitable, mechanical stiffness falls and it causes increase of electromagnetic noise, and earthquake-proof degradation. Then, it is necessary to predict correctly the oscillation characteristic of an iron core, especially natural resonance frequency, and to avoid resonance with electromagnetic vibration. In this case, the dynamic finite element method is generally used.