Harmonic weighting functions at the sliding interface of a finite-element machine model incorporating angular displacement

The formulation presented in this paper couples the magnetic vector potential and the tangential component of the magnetic field strength at a sliding interface in the air gap of a two-dimensional finite-element machine model using harmonic weighting functions which enable the use of fast Fourier transforms in combination with a simple, diagonal operator to account for the angular displacement between stator and rotor. The method applies to models where the stator and rotor meshes are nonequidistant and nonmatching at the interface. The approach substantially reduces the cost of system assembly and preconditioner setup during a transient simulation and offers convenient ways for dealing with skewing and for torque computation.