A comparative study of Luenberger observer, sliding mode observer and extended Kalman filter for sensorless vector control of induction motor drives

Observer-based sensorless techniques are becoming more and more popular and universal. This paper presents a comparative study of three kinds of observers for direct field oriented controlled (DFOC) induction motor (IM) drive: Luenberger observer (LO), sliding mode observer (SMO) and extended Kalman filter (EKF). Each kind of observer employs the dynamic full-order IM model and mechanical equation is introduced to improve the performance of speed estimation. Theoretical principles of the three observers are illustrated. Not only computer simulations, but also a series of experimental results are presented to evaluate the performances of the three observers. A comprehensive analysis and comparisons are given from several aspects, such as steady state accuracy, dynamic performance, low speed operation, parameter sensitivity, noise sensitivity and complexity. The advantages and disadvantages of each observer are summarized and a comprehensive conclusion is given.