In the paper we present the stability study of the Kalman estimator used in a vectorial drive system of an induction motor with short-circuited rotor. We consider that the control system for speed is a vectorial system with direct orientation after the rotor flux (DFOC). Although there are suggestive experimental results, the implementation of such a system containing a Kalman filter generates serious problems because of the tuning of the covariant matrixes of the measurement noise and the process noise. Also the solving of the Riccati equations in real time is difficult. These problems, as well as the simplifier hypothesis from the determination of the mathematical model on the states space of the induction motor and the modification of the rotor resistance by temperature lead to the decrease of the estimator and control system performances. Therefore you must implement an algorithm for research of the estimator stability. This algorithm has to hold count of the sampling step of sundries processors used in the drives command. The stability study is done by the determination of the transition matrix poles.
