Asymptotic stability study of induction motor vector control systems with Luemberger observer

In this paper we analyze the asymptotic stability of a vector control system for an induction motor with short-circuited rotor that contains in its loop a Luemberger estimator. The studied control system is based on the direct rotor flux orientation method (DFOC) and the stability study is based upon the linearization theorem around the equilibrium points of the control system, emphasizing the estimated variation domain of the rotor resistance for which the control system remains asymptotically stable when the prescribed speed of the control system is close to zero. The stability study is made in both the continual and discrete cases. The mathematical model of the vector regulating system is made using a value dlambda_e-qlambda_e linked to stator current. The Luemberger estimator within the regulating system is projected based on the proportionality between the self values of the induction motor and those of the Luemberger estimator.