Novel Hybrid Coil-Based Closed-Loop Optimal Demagnetization Method for Magnetic Shielding Devices

The demagnetization process is essential for the stable operation of hybrid active–passive magnetic shielding devices (MSDs). This article proposes a closed-loop optimal demagnetization method that integrates real-time feedback and iterative control, overcoming the inherent limitations of traditional open-loop approaches. The effect of biased magnetic fields on demagnetization is analyzed and experimentally validated, and the architecture of the closed-loop system is described. Experiments on a dedicated platform demonstrate up to 99.82% reduction of residual magnetic fields, corresponding to more than one order of magnitude improvement compared with conventional methods. These results confirm the effectiveness and practical feasibility of the proposed approach for high-performance magnetic shielding applications.