Accurate Extraction of Winding Inductances Using Dual Formulations Without Source Field Computation

Dual formulations are accurate in use for computing energy-related global quantities such as inductance and providing upper and lower bounds of the unknown true values of these global parameters, which is not possible if using a single formulation. Since traditional dual formulations result in totally different algebraic matrix equations, people have to develop two different finite element (FE) programs and solve the resultant two algebraic equation systems, respectively. In this paper, two practical dual formulations for open region magnetostatic problems, where the global FE matrices are exactly the same, are adopted for extracting the winding inductances. FE formulation and implementation details are presented. Practical examples having complex windings are solved using the proposed methods to showcase the effectiveness and accuracy. High-order FE basis functions are also used to enhance the solution accuracy. The proposed method is highly useful for medium-sized industrial applications by providing guaranteed inductance parameters.