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access icon free Non-invasive load monitoring of induction motor drives using magnetic flux sensors

Existing load monitoring methods for induction machines are generally effective, but suffer from sensitivity problems at low speeds and non-linearity problems at high supply frequencies. This study proposes a new non-invasive load monitoring method based on giant magnetoresistance flux sensors to trace stray flux leaking from induction motors. Finite element analysis is applied to analyse stray flux features of test machines. Contrary to the conventional methods of measuring stator and/or rotator rotor voltage and current, the proposed method measures the dynamic magnetic field at specific locations and provides time-spectrum features (e.g. spectrograms), response time load and stator/rotor characteristics. Three induction motors with different starting loading profiles are tested at two separate test benches and their results are analysed in the time-frequency domain. Their steady features and dynamic load response time through spectrograms under variable loads are extracted to correlate with load variations based on spectrogram information. In addition, the transient stray flux spectrogram and time information are more effective for load monitoring than steady state information from numerical and experimental studies. The proposed method is proven to be a low-cost and non-invasive method for induction machine load monitoring.


    1. 1)
    2. 2)
    3. 3)
    4. 4)
    5. 5)
      • 7. Thomson, W.T., Fenger, M.: ‘Current signature analysis to detect induction motor faults’, IEEE Trans. Ind. Appl., 2001, 7, pp. 2634.
    6. 6)
    7. 7)
    8. 8)
    9. 9)
    10. 10)
    11. 11)
    12. 12)
      • 20. Negrea, M.D.: ‘Electromagnetic flux monitoring for detecting faults in electrical machines’. PhD thesis, Helsinki University of Technology, 2006.
    13. 13)
    14. 14)
      • 17. Romary, R., Pusca, R., Lecointe, J.P., et al: ‘Electrical machines fault diagnosis by stray flux analysis’. Proc. Int. Conf. Electrical Machines Design, Control and Diagnosis (Wemdcd), Paris, France, 2013, pp. 247256.
    15. 15)
    16. 16)
      • 13. Gritli, Y., Tommaso, A.O., Filippetti, F., et al: ‘Investigation of motor current signature and vibration analysis for diagnosing rotor broken bars in double cage induction motors’. Proc. Int. Conf. Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), Sorrento, Italy, 2012, pp. 13601365.
    17. 17)
    18. 18)
    19. 19)
      • 11. Frosini, L., Borin, A., Girometta, L., et al: ‘A novel approach to detect short circuits in low voltage induction motor by stray flux measurement’. Proc. Int. Conf. Electrical Machines (ICEM), Marseille, France, 2012, pp. 15381544.
    20. 20)
    21. 21)
    22. 22)
    23. 23)
    24. 24)
    25. 25)
    26. 26)
    27. 27)
    28. 28)
    29. 29)
      • 21. Kokko, V.: ‘Condition monitoring of squirrel-cage motors by axial magnetic flux measurements’. PhD thesis, University of Oulu, 2003.
    30. 30)
      • 22. Frosini, L., Borin, A., Albini, A., et al: ‘New techniques to simulate and diagnose stator winding faults in low voltage induction motors’. Proc. Int. Conf. Electrical Machines (ICEM), Marseille, France, 2012, pp. 17831789.

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