A Single Observer for Currents Estimation in Sensor's Fault-Tolerant Control of Induction Motor Drives

Abstract : This paper proposes a fault-tolerant control technique against current sensors failure in direct torque controlled induction motors drives. Several important aspects are covered in the proposed algorithm, such as the detection of sensors failure, the isolation of faulty sensors, and the reconfiguration of the control system by a correct estimation. A logic circuit ensures fault detection by analyzing the residual signal between the measured and estimated quantities, while a single modified Luenberger observer performs the task of estimating the line currents, even when all the sensors are in the faulty state. In addition, a decision logic circuit isolates the erroneous signal and simultaneously selects the appropriate estimated current signal. The proposed scheme is tested on MATLAB/Simulink environment and experimentally validated in a laboratory prototype mainly containing a dS1104 card and 4 kW induction motor.