Severity assessment of rotor faults in closed loop induction drives by different approaches

In this paper different procedures are validated to diagnose and assess the severity degree of rotor faults in closed loop controlled induction machines. The possible diagnostic indexes are investigated through spectral analysis of manipulated and controlled variables. Common control schemes have been considered to evaluate the diagnostic robustness towards operating condition and regulator parameters. Voltage injection was considered as well as a possible tool for diagnostics by analyzing the amplitude of spectral lines arising in motor input current spectrum. Experimental results guide the selection of suitable analytical models for the faulty machine. The experiments are obtained with a DSP based Current Controlled Voltage Source Inverter (CCVSI) supplying a 1.5 kW induction machine in which three different rotors differing in asymmetry degree were used.