Investigating the sources of non-uniformity in 2-D core loss measurement setups

Abstract

Two-dimensional (2-D) core loss measurements have low reproducibility and repeatability, due to several errors such in data acquisition, sensing systems and the magnetizer. The latter contributes to the variation in the sample's flux density (B) under rotational magnetization. The variation in B requires a reduction of the measurement region, stresses the power source, lowers the circularity of B and modifies its locus. This variation is analysed in four magnetizers, where sinusoidal distribution of the magnetizing winding and increasing the yoke depth, are proposed. A deep yoke will be shown to increase the magnetic loading of the sample, and mitigates the variation in B in magnetizers with non-sinusoidal fields such as the square tester. The location of B-coils can result to the overestimation or underestimation of the measured B values; affecting the core loss. Experiments showed a 14% (at ∼ 0.8 T) and 6% (at ∼ 1.6 T) difference at two locations. B-holes also increase non-uniformity in the sample; spiking of B and H at the hole regions. Numerical results will show that it has minimal effects on B (< 1%), but the local increase in the field (H) is in the order of 10$⁴$ A/m at saturation.