A new model for three-phase induction machine diagnosis using a simplified spectral approach

The aim of this paper is to present a new modelling technique of nonsymmetrical induction machine using a spectral approach for electrical and magnetic variables. It is based on the decomposition of the stator voltage and the stator current in a finite series of harmonics. For one harmonic present in both voltage and current, the model gives a dedicated impedance branch. For one harmonic in the current only, the model gives a specific current source. By neglecting saturation, the linear model gives an equivalent circuit with only voltage sources, current sources and impedances without any symmetry in the different phases. The parameters can be computed using only fast Fourier transform (FFT) of stator voltage and current. The application of this new technique has been performed for parameter determination of a three-phase 0.12 kW, 220 V/380 V, 50 Hz, 2 poles induction machine.