A synthesis method of the reduced-order extended Luenberger observer (ROELO) and its design procedure for a nonlinear
dynamic system are presented. This paper proposes a method to reduce the order of the observer and to select the observer gain
matrix. The proposed algorithm is applied for high performance induction motor drives without a speed sensor. The simulation and
experiment results show that the proposed ROELF provides both rotor flux and rotor speed estimation with good performance.