A study on multiply connected domain processing methods in magnetostatic field analysis by boundary integral equations

It is difficult to analyze magnetostatic field problems with multiply connected domains by the direct boundary element method (BEM). On the other hand, there are two methods which can solve magnetostatic field problems with multiply connected domains in double layer charge (DLC) formulation. One uses imaginary loop current to calculate exciting scalar potentials and the other uses the direct BEM to calculate exciting scalar potentials. Thus, in this study, we expand the application scope of the above methods to the direct BEM. The direct BEM is widely used with other analysis methods such as the finite element method (FEM). In that respect, it is also effective to be able to analyze magnetostatic field problems with multiply connected domains by the direct BEM. In addition, results comparing the two methods to analyze multiply connected problems in both the DLC formulation and the direct BEM have not been reported. Therefore, we compare those and systematically clarify their characteristics by calculating a toroidal core model.