A sliding mode speed and rotor time constant observer for induction machines

This paper describes a new closed loop approach to estimate induction machine speed and rotor time constant from measured terminal voltages and currents for speed/torque sensorless control. For this purpose, a new state estimator, which eliminates flux information of the machine, is defined and a Lyapunov function is derived to determine speed and rotor resistance. The proposed algorithm is analyzed and verified experimentally.