Abstract
In this paper, we discuss the solution of the linear system of equations derived from a finite element electromagnetic field simulation of a practical model in which the electromagnetic field is analyzed with effects of external circuits. To solve the linear system of equations efficiently, we introduce two preconditioning techniques recently proposed for Krylov subspace method. One is folded preconditioning and the other is A-phi block IC preconditioning. The A-phi block IC preconditioning is also one of folded preconditioning methods. Through practical simulation models, we examine these preconditioning techniques and confirm their effectiveness. Furthermore, we present a strategy for selecting the appropriate preconditioning technique, focusing on the magnitude of nonzero elements in non-diagonal blocks of the coefficient matrix.