Inclusion of interbar currents in a network-field coupled time-stepping finite-element model of skewed-rotor induction motors

In order to include the interbar currents of skewed-rotor inductor motors in finite-element analysis, a three-dimensional (3-D) model is usually necessary. In this paper a two-dimensional multislice time-stepping finite element method of skewed-rotor induction motors is presented to solve such complicated 3-D problems. It is shown that the network of the rotor cage is coupled to finite-element equations so that the interbar currents in the rotor can be taken into account. By arranging the unknowns and mesh-current equations ingeniously, the resultant coefficient matrix of the global system equations are made symmetrical. Compared with 3-D finite-element methods, the computation time for solving field equations with the proposed method is significantly shorter. The model can be used to estimate the high-order harmonic stray losses in induction motors. A comparison between computed and tested results is also given.