Wigner-Ville distribution for the detection of high-order harmonics due to rotor asymmetries

The diagnosis of rotor asymmetries in induction machines through the use of methods based on the study of the startup current has become an issue of special interest. These techniques may provide, in certain situations (unbalance supply voltages, load torque oscillations…), substantial advantages in comparison with the classical method, based on the Fourier spectrum of the steady-state current. Nevertheless, these transient-based techniques have been mainly focused on the tracing of the left sideband harmonics (LSH) introduced by the asymmetry. In this paper, Wigner-Ville distributions are applied to the detection of other high-order components introduced by the asymmetry. Their detection might help to reach a more reliable diagnosis conclusion in cases in which the tracing of the LSH may be difficult (inter-bar currents, load torque oscillations…). The results show the potential of the tool for the detection of these components as a basis to diagnose the fault.