Calculation of Natural Frequencies and Analysis of Vibration Characteristics of Stators of Electrical Machines Considering Radial Symmetric and Antisymmetric Modes

The structures of stator teeth, buckle grooves, heat dissipation ribs, junction boxes, and feet change the symmetry of the stator core and casing, especially the buckle grooves and feet, resulting in certain modes of stators corresponding to more than one natural frequency, and this phenomenon has not been fully discussed and thoroughly explored in previous studies. In this article, an analytical model for stator natural frequencies, including both radial symmetric and antisymmetric modes, is established, the natural frequency splitting laws and criteria caused by the position and number of generalized ribs are summarized. Afterwards, stator natural frequencies considering radial symmetric and antisymmetric modes are quickly and accurately predicted based on the proposed analytical method (AM), and the accuracy of theoretical analysis and calculation results is verified by performing detailed finite element analysis and prototype testing. Finally, the vibration characteristics of stators are investigated. The analysis shows that two natural frequencies corresponding to the radial symmetric and antisymmetric modes of the stator with the same order can be simultaneously excited under the action of electromagnetic forces, and both cannot be taken lightly in the analysis and reduction of electromagnetic vibrations.