Investigating the Impact of Uneven Magnetic Flux Density Distribution on Core Loss Estimation

There are several approaches for loss estimation in magnetic cores, and all these approaches highly rely on accurate information about flux density distribution in the cores. It is often assumed that the magnetic flux density evenly distributes throughout the core and the overall core loss is calculated according to an effective flux density value and the macroscopic dimensions of the cores. However, the flux distribution in the core can alter by core shapes and/or operating conditions due to nonlinear material properties. This paper studies the element-wise estimation of the loss in magnetic cores. FEM has been used to investigate the flux density distribution in the core and the loss has been estimated considering this distribution. Finally, comparative results are shown between the classical macroscopic core loss estimation using effective dimensions and the element-wise loss estimation. The presented work in this paper has been carried out for two common excitation waveforms in power electronics applications, sinusoid and square-wave and for two different core shapes, toroid and E-cores. Results show that +/- 10% discrepancy should be expected in loss estimation of the core using effective dimensions under both excitation waveforms.