Diagnosis of cage induction motors subject to unbalanced supply voltage conditions including space and time harmonics

The paper describes an analytical method which is developed for the modeling of cage induction motors (IM) including space and time harmonics effects. This model is used to predict the influence of these harmonics on the electromagnetic performances of IM drives in healthy condition and to extract significant signatures under faulty conditions such as unbalanced supply voltage. The equations which describe the transient as well as steady state behavior including the computation of machine inductances are presented, basing on the calculation of the magnetic field distribution through the machine air-gap. The proposed model is less complicated to be implemented for condition monitoring or control of IM drives. The simulation results provide useful consequences about the characteristics of the IM under unbalanced voltage conditions including space and time harmonics effects. It will be shown that the space and time harmonics influence significantly the harmonic content of the electromagnetic torque and stator currents which are used for condition monitoring of IM drives.