Optimization Method of Excitation Current for Multiple Square Coils Generating Uniform Magnetic Field in Magnetic Shieling Room

Magnetic shielding rooms (MSRs) are utilized to construct the weak magnetic field environment for precision measurement. Active magnetic compensation technology is applied to improve the performance of MSRs. Considering the limitation of structure, large and adjustable uniform magnetic fields are required to be generated by special multiple square coils (MSCs). Hence, this article presents a current linear solving algorithm (CLSA) to generate a uniform region that redesigns coils via adjusting the current ratio. The solution of coil currents is obtained by nonfull-rank system of linear equations (SLEs). The adaptive particle swarm optimization (APSO) algorithm is applied to obtain the optimal solution according to different target regions. To enhance the suitability of the coil in different scenarios, five pairs of equal distance MSCs (MSC-Equal) are selected to verify the feasibility of uniform region regulation. Compared with 3-TE coil and Merritt coil, the volume proportion of magnetic field relative error is less than 1% relatively improves by 37.71% and 93.59%, respectively. In addition, experiments of MSC-Equal verified the consistency of the theoretical analysis. As the proposed method contributes a high performance in the adjustability of uniform region, it has important significance for MSRs to construct ultra-weak magnetic space for precision measurement.