Design considerations of 2-D magnetizers for high flux density measurements

The Fieldmetric measurement of 2-D core losses requires the use of orthogonal magnetic field H and flux density B sensors that are placed in a region of very high uniformity. It is difficult to achieve uniformity in the entire measurement region, in addition to the variation of B with magnetization directions. Therefore, there is a need to eliminate and/or reduce any contribution of a 2-D magnetizer to this variation, which contributes to systematic errors. Uniformity due to the magnetizer can only be controlled at the design stage. In that regard, four 2-D magnetizers are compared based on the variation of B with changes in magnetization directions. At high flux densities, any non-uniformity in B results in very H values, thus the errors due to the magnetizer are significant. Another effect of high non-uniformity is a reduction of the measurement area. It will be shown that the choice of the magnetizer design (hence the sample shape) significantly affects the variation of B with magnetization direction. In addition, the effect of the yoke depth in mitigating this problem is presented where it reduces this variation by 50%, for certain magnetizers.