The present paper deals sliding modes control of the asynchronous motor, where the sensor mechanical speed, it replaced by a software sensor. It is an observer of a special class of the non-linear systems interconnected to an estimator. The performances of the sliding modes control of the asynchronous motor with an observer of a special class of the non-linear systems interconnected to an estimator proposed are shown by a simulation treating the evaluation of the rotor flux and rotating speed an asynchronous motor.