Power losses under sinusoidal, trapezoidal and distorted induction waveform

A setup has been developed by which one can measure magnetic power losses under arbitrary induction waveforms in the frequency range 1 Hz<f_m<100 kHz. Selected results concerning sinusoidal, trapezoidal, and distorted waveforms investigated in grain-oriented, nonoriented, and amorphous laminations are reported. The role of the excess energy loss component, which is found to approximate to a good degree a f_m^1/2 law in the five-decade f_m range investigated, is emphasized. The results are discussed in the framework of a general theoretical approach in which the hysteresis, the classical and excess loss components, and their specific law of dependence on the instantaneous induction derivative are considered separately. 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 the third-harmonic component. Loss under trapezoidal flux is predicted through a simplified analytical approach