Hysteresis loss component under non-sinusoidal flux waveforms

Abstract

Separation of total energy dissipation per magnetisation cycle into a frequency-dependent dynamic component and a frequency-independent hysteresis component is a common practise in evaluating electromagnetic losses in Si–Fe electrical steel sheet. The assumed frequency-independent hysteresis component is defined by a coefficient C 0 (J/kg). In this work, the value of C 0 was determined using a linear extrapolation method and quasi-static hysteresis energy loss per cycle. The extrapolation method gave a considerable error when applied to non-sinusoidal excitation voltages (pulse width modulation and square) in a frequency range from 25 to 100 Hz. For this reason the coefficient values obtained from the quasi-static measurements at 0.01 Hz were assumed. The product of C 0 and frequency is commonly used to calculate the proportion of hysteresis loss in the total specific loss under sinusoidal magnetisation. However, since this approach is not applicable for non-sinusoidal conditions an equation is proposed, which takes into account the contribution of the higher harmonic components. The hysteresis loss component becomes higher for more distorted waveforms as compared with the value under sinusoidal excitation. Therefore, some variability of the anomalous component contribution is expected from the loss separation.