Travelling wave excitation of nonlinear magnetic materials of significant conductivity

The travelling wave excitation of semi-infinite and finite thickness steel plate is examined using a multilayer electrical circuit concentrated parameter analogue to represent the electromagnetic field equations. Normalised characteristics of surface impedance and power input for steel plate with finite resistivity and constant permeability show that the method gives reasonably accurate results. The method is their extended to represent magnetic material which includes both hysteresis and eddy current action using a digital simulation technique, previously described. Computed values of the fundamental surface impedance and power input are determined for magnetically semihard and hard materials. Field patterns inside the material are illustrated. Some experimental results on locked rotor machines validate the predicted values