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The signal demodulation techniques

The signal demodulation techniques

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Condition monitoring of electrical machines is a broad scientific area, the ultimate purpose of which is to ensure the safe, reliable and continuous operation of electrical machines. Hence, the task of fault detection is still an art, because induction machines are widely used in variable speed drives and in renewable energy conversion systems. A deep knowledge about all the phenomena involved during the occurrence of a failure constitutes an essential background for the development of any failure detection and diagnosis system. For the failure detection problem, it is important to know if a failure exists or not in the electric machine via the processing of available measurements. This chapter provides then an approach based on a electric machine current data collection and attempts to highlight the use of demodulation techniques for failure detection for stationary and nonstationary cases.

Chapter Contents:

  • 2.1 Introduction
  • 2.2 Brief status on demodulation techniques as a fault detector
  • 2.2.1 Mono-component and multicomponent signals
  • 2.2.2 Demodulation techniques
  • Mono-dimensional techniques
  • Multidimensional techniques
  • 2.3 Synchronous demodulation
  • 2.4 Hilbert transform
  • 2.5 Teager–Kaiser energy operator
  • 2.6 Concordia transform
  • 2.7 Fault detector
  • 2.7.1 Fault detector based on HT and TKEO demodulation
  • 2.7.2 Fault detector after CT demodulation
  • 2.7.3 Synthetic signals
  • Balanced system (Ψ = 0)
  • Unbalanced system (Ψ0 = 0, Ψ1 = 2π/3, Ψ2 = -2π/3
  • Unbalanced system (Ψ0 = 0, Ψ1 = 2π/3, Ψ02 = -2π/3) under nonstationary supply frequency
  • 2.8 EMD method
  • 2.9 Ensemble EMD principle
  • 2.10 EEMD-based notch filter
  • 2.10.1 Statistical distance measurement
  • 2.10.2 Dominant-mode cancellation
  • 2.10.3 Fault detector based on EEMD demodulation
  • 2.10.4 Synthetic signals
  • 2.11 Summary and conclusion
  • References

Inspec keywords: failure analysis; condition monitoring; electric machines; fault diagnosis; demodulation; variable speed drives

Other keywords: electric machine current data collection; electrical machines; variable speed drives; signal demodulation; induction machines; renewable energy conversion systems; safe operation; continuous operation; fault detection; failure detection problem; condition monitoring

Subjects: Modulation and coding methods; Drives

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