The application of zoom FFT technique to the extraction of fault character of induction motor

Because the fault character signal frequency is very close to fundamental wave frequency during the analysis of induction motor rotor winding fault based on the frequency of stator current, though in practical application, there is only signal spectrum in very small frequency range need to be taken into account, high resolution is demanded in the range, therefore the traditional base-band FFT is difficult to analyze the fault character component of induction motor rotor winding effectively. In this paper, the application of zoom FFT to identify the fault character signal of motor is discussed, the fundamental principle of zoom FFT based on multiple modulations and its application method is analyzed. Simulation calculation and practical engineering test have indicated that zoom FFT technique based on multiple modulations can identify the nice frequency structure of a certain band and extract the character signal in stator current under induction motor rotor winding fault effectively.