RobustDirect Field Oriented Control ofInduction MotorsUsing Adaptive Observer

Thispaperdeals withthesimultaneous estimation of therotorfluxandtherotorresistance ofinduction motorsbya modified Luenberger observer. Theproposed observer assumes thatonlythemotorspeedandthestator currents aremeasured. Itscorrective termsarebasedonthederivative ofstator currents. TheuseoftheLyapunov's theory forthefluxobserver stability analysis permits togiveanadaptive lawfortheon-line rotor resistance estimation. Thisobserver iscombined witha direct field oriented control toachieve arobust speedandfluxcontrol. Simulation results arepresented toevaluate theperformances of this control-observer structure scheme.