Comparison of four fractional power order transfer function models of rotor bar

This paper presents the comparison between four fractional power order transfer function models of a rotor bar. The first model arises in the implicit form with one zero, one integer power pole and one fractional power order pole, the second model is in the explicit form with one integer power zero, the third model and the fourth model are in the explicit form with fractional power order of the numerator. The parameters of the four forms are identified by using the method of a model with the Levenberg-Marquart optimisation method. Finally, frequency responses of models are compared