A transformer stacked iron core elasticity matrix determination method, wherein
- the stacked iron core is configured as a plurality of electrical steel sheets and includes at least a first portion and a second portion,
- a constitutive equation represents a relationship between stress and strain in the first portion and the second portion, respectively, and includes elasticity matrices that are different from each other,
- each of the elasticity matrices includes, as elements of the elasticity matrix, transverse elastic moduli in two planes including the stacking direction of the stacked iron core, the transformer stacked iron core elasticity matrix determination method comprising:
- a first step of acquiring a frequency spectrum of excitation noise of the stacked iron core of the transformer;
- a second step of acquiring a frequency spectrum of excitation magnetostriction of the electrical steel sheets;
- a third step of determining, for the stacked iron core of the transformer, a first provisional value of the transverse elastic moduli in two planes including the stacking direction of the first portion and a second provisional value of the transverse elastic moduli in two planes including the stacking direction of the second portion, and calculating a frequency spectrum of a vibration response function of the stacked iron core of the transformer when the first provisional value and the second provisional value are applied to the elasticity matrices;
- a fourth step of calculating a frequency spectrum of excitation vibration of the stacked iron core of the transformer, based on frequency spectrum data of the excitation magnetostriction of the electrical steel sheets acquired in the second step and the frequency spectrum of the vibration response function of the stacked iron core of the transformer calculated in the third step;
- a fifth step of calculating a degree of coincidence between the frequency spectrum of the excitation noise of the stacked iron core of the transformer acquired in the first step and the frequency spectrum of the excitation vibration of the stacked iron core of the transformer calculated in the fourth step;
- a sixth step of calculating the degree of coincidence for each combination of the first provisional value and the second provisional value by changing the first provisional value and the second provisional value respectively and repeating the third step to the fifth step;
- and
- a seventh step of detecting a local maximum value of the degree of coincidence calculated for each combination of the first provisional value and the second provisional value in the sixth step, adopting the first provisional value when the degree of coincidence is a local maximum value as the transverse elastic moduli in two planes including the stacking direction of the stacked iron core of the first portion, and adopting the second provisional value when the degree of coincidence is a local maximum value as the transverse elastic moduli in two planes including the stacking direction of the stacked iron core of the second portion, and
- the sixth step comprising:
- a step 6-A of, when each combination of the first provisional value and the second provisional value corresponding to the degree of coincidence is expressed as a trial point plotted in a two-dimensional space with the first provisional value as a first axis and the second provisional value as a second axis, sequentially selecting points distributed within a defined range of the two-dimensional space as the trial points and calculating the degree of coincidence for each combination of the first provisional value and the second provisional value corresponding to the trial points;
- a step 6-B of setting a limited sub-region in the two-dimensional space based on the degree of coincidence calculated for each combination of the first provisional value and the second provisional value corresponding to the trial points;
- and
- a step 6-C of setting search points in the limited sub-region at positions between the trial points and calculating the degree of coincidence for each combination of the first provisional value and the second provisional value corresponding to the search points.