The detailed design procedure for the extended Luenberger observer is presented. The main features are discussed and compared with the characteristics of the extended Kalman filter which is conventionally used for joint state and parameter estimation. The extended Luenberger observer is applied in high-performance induction-motor drives with and without a speed sensor. Results from an extensive series of simulation studies are presented. These show that the extended Luenberger observer provides both rotor-flux and rotor-resistance, or rotor-flux and rotor-speed, estimates with excellent transient and steady-state performance. Experimental results verify the basic extended-Luenberger-observer algorithm.