New natural observer applied to speed-sensorless DC servo and induction motors

A simple observer design technique with parameter adaptation is proposed for bounded-input bounded-output nonlinear systems. In this technique, no feedback is used in the observer but parameter estimations are considered as if they are observer inputs. The proposed technique is successfully applied to speed-sensorless dc servomotors and speed-sensorless induction motors with load torque adaptation schemes. The observer is robust to noise and parameter uncertainty. Excellent experimental and simulation results have been obtained.