Diagnosis of induction machines under transient conditions through the Instantaneous Frequency of the fault components

This paper introduces a methodology for diagnosing different types of faults of induction machines working under transient conditions; the method is based on the extraction of the Instantaneous Frequency (IF) of the fault related components of stator current. It is shown that the IF of the fault components, evolves in the time-frequency and slip-frequency planes following characteristic patterns, different for each type of fault; the identification of these characteristic patterns, which are theoretically explained, is proposed as the base of the diagnosis method. This paper also introduces several mathematical approaches which enables for the extraction of the instantaneous frequency of the fault components of the transient stator current. Each of this methods is explained and also and validated with both simulated and tested signal. A comparison of the different methods for extracting the instantaneous frequency of the fault components is also given.