Analysis of synchronous parasitic torque in dual skew cage rotor induction motors with equivalent slot number

摘要

The squirrel-cage induction motor with equivalent slot number may have starting problem due to synchronous locking torque. This study adopts dual skew rotor structure to solve that problem. First, the distribution of rotor slot harmonics is described. Second, the synchronous parasitic torque acting on the rotor is calculated. Eddy-current field simulation is implemented to calculate locking torque in three kinds of structure rotors squirrel-cage induction motor with equivalent slot. The induction motor with straight rotor hardly line starts in some rotor position, which illustrates that skew rotor can attenuate the synchronous parasitic torque, but cannot remove it. The dual skew rotor can remove the synchronous parasitic torque in which odd rotor slot harmonics interact with the unassociated stator harmonics, and also attenuate others. The validity of this rotor structure is verified by simulation study and also experiment.