1. Background and subject
As electromagnetic devices become more and more efficient, the precision in iron loss analysis becomes more important for electromagnetic field analysis. Synchronous motors using rare earth permanent magnets are especially suitable for electrical appliances and electric automobiles. To improve the efficiency of these products, measuring iron loss with high precision is needed.
When calculating the eddy current loss in magnetic steel, conventionally, a Fourier transform is taken of the magnetic flux density derived from analysis and compared with actual measurements of the iron loss characteristics to estimate the eddy current loss. (Fig. 1 below, conventional method). However, if the conditions differ from the iron loss characteristic measurements, high precision analysis cannot be carried out. For example, this occurs in cases where the frequency used in the analysis is higher than the upper limit frequency, or when DC is superimposed on AC. The essential thing is to model the steel sheet and solve for the current distribution in the steel sheet using a physical model; however, to faithfully model the steel sheet, the increase in the number of elements results in an impractically large amount of time needed for calculation.