Hybrid FE/BE Implementation on Electromechanical Systems With Moving Conductors

Modeling of an electromechanical system with a moving conductor, such as the armature in a railgun or the slip ring in homopolar motor, poses major numerical challenges. One reason is the need for air region mesh. Modeling the conductors that move through the air region requires either remeshing or special mesh topology. Furthermore, the generation of air mesh is not trivial, particularly for conductors with complex geometry, like windings in rotating machines. The electromagnetic field in the air is governed by the Laplacian equation, one of whose main characteristics is that the values in the domain can be represented by the boundary values through boundary integration. Applying the boundary-element method for the air region and the finite-element (FE) method for the conductors eliminates the air mesh requirement, thus easing model generation and facilitating the creation of models with forward-moving conductors. This paper will present the detailed hybrid algorithm as implemented in EMAP3D, the results of a sample railgun simulation, and a comparison of the FE method to the hybrid FE/BE method