A cylindrical model of a stator and frame system of induction motors is proposed for a complete analysis of natural frequencies, and parametric studies are made with respect to several design variables.
The analytical approach taken is to use a series expansion based on the separation of variables technique for the Helmholtz potentials. The force boundary conditions and the compatibility at the interface were expressed as a recurrence matrix equation. The resulting characteristic equations are then solved numerically obtaining frequency spectrums in terms of the wave numbers in the three coordinates.
The results are compared with existing analytical solutions for a simple cylinder case and measured values for the model with the effect of teeth and windings. Important modes for the study of noise and vibration are identified and shown to be dependent of the dimensional differences. Stator length, core thickness, frame thickness and materials are changed for parametric study. It is found that their influences shows rather complex nature and depends on relative sizes. This indicates that the frequencies corresponding to various modes change in order for different dimensions and care should be exercised in utilizing the results of the parametric study.
