Parameter calculation based on perturbation theory for fault conditions of induction motors

When motor faults (rotor broken-bar, stator turn- to-turn short, etc.) occur in a motor, its internal current distribution and electromagnetic field will change, which will further cause some variations to stator and rotor parameters. In this paper, the method conjoint of Finite Element Method and Energy Perturbation Method is used to calculate the motor´s inductance parameter, and finite-element method is used to calculate the gross energy of internal magnetic field, and perturbation theory is used to calculate the motor´s inductance parameter. The variation of inductance parameter under fault conditions is analyzed to generalize principles about variation of inductance parameter before and after the fault. From the results we can conclude that the magnetic energy will more and more numerous along with the increasing number of rotor broken-bar, and will become smaller along with the increasing degree of turn- to-turn short. Along with the increasing number of rotor broken- bar, stator winding self-inductance will be influenced little, but the self-inductance would be smaller and smaller along with the increasing degree of stator turn-to-turn short. The calculation parameter in this paper can be used to analysis of motor faults.