Robustness and limitations of sensorless technique based on Luenberger state-Observer for induction motor drives under inverter faults

The aim of the present paper is double; the first is to implement a sensorless Indirect Stator Field Oriented Control (ISFOC) of three phase induction motor drive based on the Luenberger Observer (LO). The second is to study the robustness and the limitations of the proposed sensorless vector control technique under abnormal operations of the electric drive. The proposed sensorless strategy is based on an algorithm permitting a better simultaneous estimation of the rotor speed and the flux linkage including an adaptive mechanism based on the Lyaponov theory. To study the reliability, the robustness and the limitations of the sensorless technique to abnormal operations, some experimental tests have been performed under several cases: single open switch damage in a leg, multiple faults involving two transistors belonging to the same inverter leg. For healthy and faulty operation mode, an experimental setup based on a 3kW squirrel-cage induction motor has been used.