Finite element analysis of cage induction motors fed by static frequency converters

A calculation of induction motors based on the finite-element analysis of the magnetic field is presented. The field is assumed to be two-dimensional, and the time dependence of the field and the motion of the rotor are modelled by the Crank-Nicholson time-stepping method. The nonsinusoidal voltage supplied by the frequency converter is imposed on the formulation through the circuit equations of the winding. The method was tested using the properties of a 15-kW cage induction motor. The results obtained for the current and torque show good agreement with the measured results. The method was also used successfully for computing the resistive losses of the rotor winding and for analyzing the effect of the bar shape on the resistive losses