Flux penetration and losses in steel plate with nonsinusoidal magnetisation

The cyclic magnetisation of steel plate with either nonsinusoidal magnetising force or nonsinusoidal voltage excitation is examined. The influence of the phase and the magnitude of the harmonic component of excitation is determined, together with profiles of flux density, voltage and magnetising force, at different depths and for a wide range of plate thicknesses and frequencies. A digital simulation technique, previously described, is used to compute theoretical values which include both hysteresis and eddy-current effects in the ferromagnetic material. Measured values of loss, flux/magnetising current loops and voltage waveshapes show good agreement with predicted values. A companion paper examines the cyclic magnetisation of non-grain-oriented low-loss steel laminations with nonsinusoidal excitation and computes theoretical values of loss, flux density and magnetising current waveshape.