Determination of the starting and operational characteristics of a large squirrel cage induction motor using harmonic and transient FEM

The harmonic and transient finite element method (FEM) are used to determine the starting and operational characteristics of a large induction motor (IM). The starting properties of the initially proposed motor are strongly degraded by parasitic asynchronous crawling tendencies and the motor is unable to achieve the nominal rotor velocity. It is shown in this paper that, when analyzing the IM using the time-harmonic procedure only, these parasitic effects are not detectible. In order to enable the detection of all the effects provoked by higher harmonics the designing process has been expanded by the use of a transient numerical analysis coupled to the equations of motion. The acceleration torque, position and rotational speed of the rotor are recalculated at every time step. This way, the estimation of the newly proposed motor´s design is realizable, based on the simulation results only. The numerical results are compared with measurements.