Optimization in measurement of DC magnetic properties of permalloy sheet using wavelet transform and dynamic zero-bias compensation

The shielding ability of the magnetic shielding room (MSR) is related to the DC magnetic properties of the shielding materials. To optimize the magnetic properties’ measurement accuracy for improving the repeatability and reliability of the measuring system, a method of wavelet transform (WT) combined with dynamic zero-bias compensation (DZBC) is proposed in this paper. The improvement of signal accuracy reaches 19.31% to 46.70%. Moreover, the sheet specimens with different annealing processes are measured with the optimized system. The ratios between standard deviation (SD) and mean value from results are around 0.66% to 1.74%. Finally, the finite element method (FEM) is introduced to verify the shielding performance in magnetic shielding boxes with the measured magnetic properties. The remnant magnetic field deviation between the simulation and the experiment result is less than 4.6nT, which demonstrates that the optimized method brings important significance for the remnant magnetic field analysis in the MSR.