Influence of Constant Values and Motor Parameters Deviations on the Performance of the Adaptive Sliding-mode Observer in a Sensorless Induction Motor Drive

The adaptive sliding-mode observer has been widely used to estimate the rotor flux and rotor speed in inverter-fed sensorless induction motor drives. However, the technique requires setting a priori the sliding-mode observer constants and also knowledge of the induction motor parameters. This particular aspect can cause significant errors in the estimation of the rotor speed used in sensorless control schemes. Changes in the induction machine parameters due to temperature or different saturation levels will affect the dynamic operation of the observer despite its adaptive nature. In this context, a sensitivity study of the adaptive sliding-mode observer is presented and discussed in this paper. Various experiments are performed on a sensorless indirect vector-controlled induction motor drive under a variety of conditions to verify the observer robustness.