Adaptive flux observers and rotor speed sensor fault detection in induction motors

Abstract

The problem of detecting a rotor speed sensor fault in induction motor applications with load torque and rotor/stator resistances uncertainties is addressed. It is shown that in typical operating conditions involving constant rotor speed and flux modulus and non-zero load torque, a constant non-zero (sufficiently large) difference between the measured speed and the actual speed may be on-line identified by an adaptive flux observer which incorporates a convergent rotor resistance identifier and relies on the measured rotor speed and stator currents/voltages. Simulation and experimental results illustrate the effectiveness of the proposed solution and show satisfactory fault detection performances.