The Effects of Neglecting Stator Transients in Induction Machine Modeling

The dominant eigenvalues of the linearized reduced order model of an induction machine in which stator transients are neglected are compared with the dominant eigenvalues of the linearized full model. How closely the eigenvalues agree is shown to depend both on machine parameters and load inertia. Computational results indicate that in most situations a very simple criterion, (RsRr/X22) < (1/10K¿), can be used to s rZ check whether the reduced order model is accurate (K¿ being the ratio of the rotor transient time constant to the static electromechanical time constant). An intuitive understanding of when and how the dominant eigen- values of the reduced order model differ from those of the full model is obtained utilizing root loci plots. An examination of the accuracy of the zeros, and hence the step response, is also included.