Finite element torque calculation in electrical machines while considering the movement

Different methods are presented for the calculation of torque as a function of rotation angle in an electrical machine. These methods are integrated in a calculation code by using the finite element method. The movement is taken into account by means of the moving band technique, involving quadrilateral finite elements in the airgap. The torque is calculated during the displacement of the moving part by using the following methods: Maxwell stress tensor, coenergy derivation, Coulomb´s virtual work, A. Arkkio´s method (1988), and the magnetizing current method. The results obtained by the different methods are compared with experimental data and make it possible to obtain practical information concerning the advantages and limitations of each method