Sensorless detection of rotor-cage-defects for inverter fed induction motors

This paper presents a sensorless detection system for cage defects in squirrel cage induction motors. Second order effects, like field and voltage harmonics, core currents and torque ripple caused current sidebands are integrated in a novel machine model for cage defects. In addition, the harmonic analysis displays a way how the machine speed can be calculated out of the current spectrum. The experimental test for inverter fed induction motors of the diagnosis system reveals the ability to diagnose a defective cage.