Implementation of full order observer for speed sensorless vector control of induction motor drive

In this paper, the implementation of the speed sensorless vector control of induction motor (IM) drive based on full order observer in real-time is presented. To decrease the associated maintenance costs, adaptive full order observer is used to estimate the rotor speed. The adaptive full-order observer based on IM equations is used to estimate stator currents and rotor flux. The speed is estimated depends on the error between the actual and estimated stator currents. However, the performance of this scheme deteriorates when approaching the zero speed zones because the effect of the variation of the stator resistance and the problem of the stability. The stator resistance has been estimated in parallel with the rotor speed to compensate the error in estimated rotor speed in the low speed region. Lyapunov´s stability criterion is employed to estimate rotor speed and stator resistance. This paper presents an experimental evaluation of the performance of speed observer when working at very low. Synthesis of the controller has been presented. The simulations and experiments results prove excellent steady-state and dynamic performances of the drive system in a wide speed range, especially at very low speeds, which confirms validity of the proposed scheme.