Rotor motion in the dynamic finite element analysis of rotating electrical machinery

In the analysis of rotating electrical machinery, the need often arises to analyze machines at different rotor positions. This may be for simple studies such as for obtaining the direct and quadrature axes reactances in a synchronous machine, or for a more complex time domain analysis, where the rotor assumes different positions with time. The obstacle to allowing the rotor to rotate, is that the integrity of the mesh is disturbed as the nodes of a finite element mesh cross edges. Indeed, in studies of electromechanical dynamics, a two-fold challenge is posed in first rotating the rotor and secondly in doing so to a position which may be revealed only as computation proceeds. This paper presents a novel method of rotating the mesh which is made adaptive through the application of the Delaunay criterion for optimality. The application of such adaptive rotating meshes in machine dynamics is then investigated. It is shown that the methodology of this paper paves the way to constructing general software models of rotating machines.