MAGNETIC-FIELD ANALYSIS IN SQUIRREL CAGE INDUCTION-MOTORS

The calculation of the magnetic field in a squirrel cage induction motor forms the basis of all design procedures. In this paper, a method is discussed to analyse the field in the machine, starting from a classical design scheme but using the finite element technique. Starting from the data as for a classical design, the method is intended to be useful for a designer in a factory who may not be familiar with finite elements. Hence, it must be a totally transparent unit, having an output similar to the one the designer is used to. The mesh generation starts from little data: the slot geometry for stator and rotor, the number of rotor and stator slots, the inner and outer stator and rotor diameters and the winding design. An automatic mesh generation process is started. The programme is designed in such a way that it can account for the different problems encountered by designers. The currents are fed into the model, with starting values found from a classical, analytical approach. The system is modelled using a modified stepwise linearized eddy current approach. The adapted eddy current approach may be used for any three phase system, including both eddy currents and saturated magnetic material.