Eddy Current Losses in Solid Iron With DC Offset

A numerical solution of the one-dimensional diffusion equation is used to calculate eddy current losses in solid iron for ac with dc offset exciting current. The results are compared with test data obtained on a solid iron ring at several frequencies from 50 Hz to 600 Hz. Curves of loss versus field amplitude and offset are presented for sinusoidal excitation with the plate temperature at 100°C. Several three-dimensional plots show how field intensity varies with time and distance into the plate. The importance of accurate representation of the material B-H curve is stressed.