Rotor fault and location detector for induction motors

摘要

A method and apparatus for detecting rotor faults in an induction motor. Such induction motors have a stator and a rotor comprising a multiplicity of rotor bars. The flux around the rotor bars is detecte at a predefined flux detection point in the motor, generally by using a coil wound around one of the stator teeth. A synchronization signal is generated once per revolution of the rotor when a predefined position on the rotor is closest to a stator reference point, usually the flux detection point. The detected flux signal is filtered to reject signals in a predefined frequency band around the frequency at which the rotor bars pass the flux detection point, and then it is synchronously time averaged. Averaging requires that corresponding portions of the flux signal, for a series of rotor revolutions, be added, and the synchronization signal is used as a reference for matching corresponding portions of the flux signal. Statistically significant peaks in the resulting time averaged signal indicate the presence of a rotor bar fault, and the location of such peaks corresponds to the location of rotor bar faults with respect to the predefined position on the rotor.