Rotor induction machine failure: Analysis and diagnosis

The numerous qualities of asynchronous machines enhance their use in industry. However, various faults can occur, such as stator short-circuit and rotor failures. We focus our study on the latter since the unknown evolution of currents in the squirrel cage makes the detection of the rotor's failures very difficult. In this paper we first present the effects of the rotor failures by means of a finite element model. In the second part we, present our strategy of monitoring for this kind of fault. We synthesize a so-called 'reduced-order extended high-gain observer' which follows the on-line evolution of an equivalent rotor resistance using a Park model. It provides an on-line alarm. However, this parameter is not enough to indicate the presence of an actual fault, thus we synthesize an extended Kalman filter to survey the three rotor resistances of a three-phase model. This provides an off-line analysis by verifying the balanced state of the rotor resistances.