Condition monitoring of stator faults in induction motors: Part I– Analytical investigation on the effect of the negative voltage sequence.

The aim of this part of paper is to describe through an analytical analysis in steady state operation the impact of unbalanced voltage supply on induction machine performance. The proposed study is based on the KU reference frame theory, taking into account only the negative sequence components effect. New accurate formulas of the fundamental and negative sequence components in the stator currents and also the speed and torque ripples are developed. The proposed formulas correlate very well with the simulation and experimental results.