Stability Analysis and Design of Adaptive Observer Based on Speed Sensorless Induction Motor

By analyzing the existence of unstable regions of the present adaptive observer using pole-placement technique in regenerating mode at low speeds, conditions that ensure the adaptive observer stability at full speed regions are got. An improved speed adaptive law and a novel method to choose the gain of the observer are proposed based on observer. By using the Lyapunov stability theory, speed identification adaptive law is got. The gain of the observer can be obtained by solving two bilinear matrix inequalities. The simulation model of speed sensorless induction motor using direct torque control based on observer is built in the Matlab/Simulink. Simulation results show that the adaptive observer has good steady and dynamic performances and good robustness.