Reliable detection of rotor electrical faults in induction motors using frequency extraction of stator current and stray magnetic flux signals

  • Panagiotis Panagiotou

    Student thesis: Doctoral ThesisDoctor of Philosophy


    A recent and continuously developing trend in Fault Diagnostics (FD) of Induction Motors (IM)is the measurement of electromagnetic fields attenuated in the vicinity of the machine for diagnostic purposes. This type of analysis is referred to as Stray Flux Signature Analysis (SFSA) and has proven at least as valuable as the traditionally applied Motor Current Signature Analysis (MCSA). The stray fields are captured with magnetic field sensors or with the use of search coils as induced voltage, which is the final signal of interest to apply Digital Signal Processing (DSP) and FD.

    To this direction,the presented thesis has contributed in the field by proposing a diagnostic solution for a specific type of faults, rotor faults. The method is referred to as frequency extraction, as it is based on the extraction of frequency information with advanced DSP, and takes advantage of the fault related speed ripple effect during the steady-state operation. Initially, it is successfully applied on stray magnetic flux measurements, a purpose for which special sensor coils were also designed and constructed. Afterwards, the method is demonstrated on measurements of stator currents as the most traditional measurement in FD. The validation of the method regarding both stray flux and stator currents is done with Finite Element (FE) simulations and experimental measurements.

    Date of AwardSept 2020
    Original languageEnglish
    Awarding Institution
    • Coventry University
    SupervisorNeophytos Lophitis (Supervisor), John Arvanitakis (Supervisor) & Konstantinos Gyftakis (Supervisor)

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