Time-Varying Parameter Identification of a Class of Nonlinear Systems With Application to Online Rotor Resistance Estimation of Induction Motors

In this paper, algorithm for time-varying parameter estimation of a large class of nonlinear systems is presented. This method is based on the variable structure theories. The algorithm developed is potentially useful for adjusting the controller parameters of variable speed drive and can be used for both constant and time-varying parameter estimation. The real-time estimation of the rotor resistance of an induction motor based on this approach, show rapidly converging of estimates in spite of the measurement noise, discretization effects, parameter uncertainties (e.g. inaccuracies on motor inductance values) and modeling inaccuracies. The robustness analysis for induction motor application also revealed that the proposed scheme is insensitive to the stator resistance variations. The merits of the proposed algorithm in the case of time-varying parameter are demonstrated via experimental results in various operating conditions of the induction motor