Torque Maximization and Sensorless Control of Induction Motor in a Flux Weakening region

In this paper, one presents a transient state performance optimization of vectorcontrolled induction motor (IM) drives operating in the field-weakening region. The vector control scheme, based on the rotor flux field-orientation (RFOC), is considered to ensure maximum torque motor operation regime. Although in the high speed region, the measure of rotor speed and the sensitivity to parameters errors of the motor still remains a problem. In this context, one proposes an approach that ensures sensorless control and maximum torque operation maintaining robustness essentially to rotor resistance variation. Also, the speed sensorless control used for the motor drives able to obtain correct rotor speed through sliding mode rotor flux observer (SMRFO) under RFOC method. The estimation speed algorithm is sensitive to rotor resistance; witch is adapted on line using the Lyapunov stability theory. Simulation results demonstrate the performance of the proposed robust speed sensorless torque maximisation control scheme in response to high-speed demands and rotor resistance variations Keyword: Induction machine, Torque Maximisation, Flux Weakening, Sensorless Control, Sliding Mode Observer.