Influence of manufacturing processes on iron losses

One of the important issues in the determination of induction motor efficiency is the prediction of iron losses in the magnetic circuit. This in essence requires a knowledge of the time variation of the flux density in the steel followed by the knowledge of the iron losses appropriate to that waveform and lamination material. Add to that the influences of manufacturing processes such as mechanical stress, punching, heating etc. and this very quickly produces an intractable problem. The introduction of numerical techniques such as the finite element method however has provided the designer with access to highly detailed flux density information at all points in the machine. The objective of this paper therefore is to describe a suitable analytical iron loss model for routine design office use and to examine the influence of certain manufacturing processes on the iron losses in lamination electrical steel.