Core loss calculation for magnetic materials employed in SMPS under rectangular voltage excitations

Magnetic materials are widely used in switching-mode power supplies (SMPS) and magnetic components in SMPS usually work under two typical rectangular excitations (with or without the period of zero voltage). Extensive experimental results have shown that there is quite a difference of core loss between sinusoidal excitations and rectangular excitations, which means the traditional core loss calculation methods are no longer applicable. In this paper, two formulas for core loss calculation under the above rectangular excitations are derived based on the Improved Generalized Steinmetz Equation (IGSE). Core loss of different magnetic materials, under both sinusoidal excitations and rectangular excitations with different frequencies and duty cycles, are measured. Experimental results show that the formulas are accurate enough and very useful to predict the core loss.