A Constant Gain Adaptive Observer for Speed and Resistances Identification

This paper presents a new adaptive flux observer with a constant gain for speed identification. The theory of Lyapunov stability is used to design adaptive flux observer and speed estimator. The stability of flux observer is gauranteed by a linear matrix inequality (LMI), and the constant observer gain is obtained by solving the LMI with LMI toolbox in MATLAB. The problem of unstable region which arises from using pole-placement technique is overcome. Based on the proposed flux observer, the adaptive laws for estimation speed is given. Finally, a sensorless induction motor drive is designed by using the speed adaptive estimation scheme and the direct torque control technique for torque and stator flux control. The speed sensor-less direct torque control IM drive system is capable of working from very low speed to high speed and exhibits good dynamic and steady-state performance. The steady-state and dynamic performance of the proposed sensorless drive are demonstrated using simulation and experimental results