Design of Highly Uniform Radial Coils Considering the Coupling Effect of Magnetic Shielding Cylinder

Abstract

This article proposes a novel design method for highly uniform radial coils in a magnetic shielding cylinder (MSC) with high permeability. It solves the problem that the uniformity of coils in the MSC decreases because of the coupling effect between the coils and high-permeability materials. The coupling effect between the MSC and coils is analyzed, and the analytical model of the magnetic field generated by saddle coils in an MSC is presented. Furthermore, through the extensive use of the Taylor expansion method, target field information, and particle swarm optimization (PSO) algorithm, the uniformity of target region is improved. The simulation results demonstrate that in the target region, compared with the six nested saddle coils without coupling design, the maximum magnetic-field relative error of the designed coil decreases from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.05\,\, {}\times {}{10^{-3}} $ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.32\,\, {}\times {}{10^{-4}} $ </tex-math></inline-formula> , and the space proportion of magnetic-field relative error less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\,\, {}\times {}{10^{-4}} $ </tex-math></inline-formula> increases from 23.39% to 79.26%. The experimental results also have good consistency with the theoretical results, verifying the effectiveness of the proposed method. These results confirm that this method can provide a uniform field in an MSC for the background magnetic-field zeroing of a magnetocardiography (MCG) system.