State and parameter estimation in induction motors using sliding modes

We present two observer based solutions to the popular problem of sensorless speed control of induction motors. The observers which provide simultaneous motor speed and flux estimation are based on the basic principles of sliding mode control theory. We present an observer, which incorporates rotor flux dynamics, that can also be used to simultaneously estimate rotor resistance (if unknown). We propose a second observer design, defined by stator flux dynamics, that is independent of the unknown rotor resistance. As for the controller of the induction motor itself, which now relies on the outputs of each observer, we propose designs again based on sliding mode control theory.