High accuracy calculation of magnetic field by improved 3-D boundary magnetic charge method

In this paper we propose a three-dimensional (3-D) boundary magnetic charge method (BMCM) in order to treat a static magnetic field system where there is a great difference in magnitude of permeability between neighboring magnetic materials. The method is based on the improved 3-D boundary or surface charge method (BCM or SCM) developed for high-accuracy calculation of the potential and electric field distributions in a composite dielectric system. The calculation of magnetic field by the 3-D BMCM is completely parallel with the calculation of the electric field by the 3-D BCM. The numerical accuracy of the 3-D BMCM is examined by using a computing model which gives an analytical solution of the magnetic field. We have found that the numerical accuracy of the present method is independent of the magnitude of the permeability and improves in proportion to the square of the number of the small surface elements.