Influence on Vibration and Noise of Squirrel-Cage Induction Machine With Double Skewed Rotor for Different Slot Combinations

Quiet induction motors are in great demand at industrial manufacture and social activities. A double skewed rotor structure can effectively reduce an electromagnetic noise by eliminating odd-order radial electromagnetic force and weakening even-order radial electromagnetic force, which are generated by a harmonic field. In this paper, orders of electromagnetic force for different slot combinations are analyzed. The natural frequency of stator is calculated by a modal analysis. Spatial and temporal variation characteristics of radial electromagnetic stress wave of the motor are calculated by a finite-element method, and analyzed in space and time domains by the 2-D Fourier analysis. The induction motor is quiet when both the vibration mode and the frequency of electromagnetic force wave keep away from the resource mode and the natural frequency of stator core. The quietest induction motor is found by means of the comparison with four different slot combinations.