Signature frequency analysis for diagnosis of induction motor systems

This paper analyzes the frequency spectrum of current and power of the inverter-driven induction motor under abnormal operating condition. The specific frequency caused by the abnormality is called the signature frequency. This paper derives first a model for detecting the signature frequency of the induction motor in an abnormal operating condition on the basis of the dynamic equations of the motor. Next, the signature frequencies of current, power and torque waveforms of an induction motor driven by three kinds of power sources are discussed.