Transient analysis of cage-induction motors using finite-elements

A method for the analysis of induction motor transients using the two-dimensional finite-element method is described. Unlike previously published work the method does not use an eddy-current formulation to account for the currents induced in the rotor bars. It relies on the decomposition of the rotor currents into harmonic distributions and the use of auxiliary circuit equations to take the time-stepping into account. The adoption of this technique yields some distinct advantages. Firstly, time-stepping is limited to the circuit model alone, thereby allowing an optimum step size to be selected at all times. Secondly, the use of a magnetostatic finite-element formulation makes it possible to use nonlinear solutions of comparatively low accuracy, thus bringing substantial savings in computer resources. Finally, the extensive use of circuit techniques also allows the effect of axial skew and spatially distributed airgap flux harmonics to be incorporated.<>