POWER LOSSES UNDER SINUSOIDAL, TRAPEZOIDAL AND DISTORTED INDUCTION WAVE-FORM

A set up has been developed by which we can measure magnetic power losses under arbitray induction waveform in the frequency range 1 Hz < f < 100 KHz. Selected results are here reported concerning the case of sinusoidal, trapezoidal and distorted waveforms, investigated in grain-oriented, non-oriented and amorphous laminations. The role of the excess energy loss component, which is found to follow to a good degree of approximation a fm1/2 law upon the investigated five decade fm range, is emphasized. The results are discussed in the framework of a general theoretical approach, where the hysteresis, classical and excess loss components and their specific law of dependence on instantaneous induction derivative are separately considered. A formulation for total power losses under arbitrary induction waveform is provided and applied, in good agreement with experiments, to the case of distortion introduced by third harmonic component. Loss under trapezoidal flux is predicted through a simlified analytical approach. © 1990 IEEE