Sliding-Mode Observer with Resistances or Speed Adaptation for Field-Oriented Induction Motor Drives

A sliding-mode observer working in parallel with a particular adaptive scheme is proposed for field-oriented control of induction motor. The observer detects the rotor flux components in the two-phase stationary reference frame. The adaptive scheme is able to on-line estimate either the motor resistive parameters or the rotor speed. In the former case, the adaptive scheme allows to have continuously the exact values of the stator and rotor resistances, parameters usually subjected to variations from their nominal values. In the second one, the scheme can be used to realize an induction motor sensorless speed control. The analytical development of the sliding mode observer and the adaptive scheme is fully explained. Simulation results, based on a Matlab/Simulink/real-time-workshop model designed on purpose, are presented to verify the validity of the proposed adaptive observer structure