The paper deals with mathematical models of an induction motor which are used for control algorithms of AC drives with induction motors. The first part of the paper describes a current model of the induction motor which is used in the model reference adaptive system as a reference model for a stator resistance estimator. The next part deals with a voltage model, which uses for the determination of the individual rotor flux vector components integration without feedback, whose basic disadvantage is time dependent offset of output quantity.
In the paper, there is described a solution of the integrator with the offset elimination. The voltage model of the induction motor works with the voltage drop on the stator resistance which is depending on temperature changes. Therefore there is described the stator resistance estimator which uses the model reference adaptive system. The correct activity of the described rotor flux estimator and stator resistance estimator is confirmed by simulations in Matlab-Simulink.