Application of a Current Sheet in BEM Analysis for Numerical Calculation of Torque in the Magnetostatic Field

In this article, an application of a current sheet as a finite element in the boundary element method (BEM) is described. A detailed procedure for mathematical and software implementation of a current sheet element (CSE) as a finite boundary element (FBE) in BEM analysis is presented. For a simple generic magnetic circuit with a stator and a rotor, the calculated magnetic field and torque values are compared with the values obtained by two different finite-element method (FEM)-based simulation programs showing good agreement; however, elucidating the fact that even by employing professional FEM tools, on fairly simple problems, accurate determination of forces and torques is not necessarily guaranteed. Certain aspects of using the Maxwell stress tensor (MST) for the determination of forces and torques on the rotor domain are discussed. Since the primary magnetic field sources are currents in a set of conductors of the circular cross section, analytical expressions are used for the calculation of the primary field. Due to the selected geometry of the FBEs, i.e., CSEs, after a numerical determination of their currents by BEM, analytical expressions are employed for the calculation of FBE fields as well.