Comparative Analysis of Core Loss Calculation Methods for Magnetic Materials Under Nonsinusoidal Excitations

Magnetic components in power electronic equipment usually suffer from nonsinusoidal excitations. In this paper, a brief description about the existing core loss calculation methods for nonsinusoidal excitations is given. Then calculation formulas of aforementioned methods for two typical excitation waveforms, that is, square and rectangular with variable duty cycle D, are derived. Core loss of nanocrystalline FT-3KS, under above two nonsinusoidal excitations, is measured on an established test setup. The accuracy and applicability of each method are discussed theoretically and verified experimentally, especially in terms of different duty cycles and frequencies. It is found that the waveform coefficient Steinmetz equation (WcSE) is more applicable for the case of relatively small harmonics content of magnetic field intensity H (normal duty cycle region), while the improved generalized Steinmetz equation (IGSE) has better precision where the harmonics count (extreme duty cycle region). In addition, the IGSE can better follow the changing trend of core loss with D and have better frequency applicability than WcSE, which is proven to be not valid in low frequency (where the static hysteresis loss dominates). The results can provide reference for core loss prediction under nonsinusoidal excitations.