Method for detecting a fault in an induction machine
AssigneeDanfoss Drives A/S
InventorKarl-Peter Simon
Life of this patent
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Abstract
The invention concerns a method for detecting a fault in a rotating field machine, in which current components are analysed in a flux-based, particularly rotor-flux-based, coordinate system a flux-forming current component being subjected to a frequency analysis in the flux-based, particularly rotor-flux-based, coordinate system. It is endeavored to provide a simple method for an early detection of faults. For this purpose, a current operating point is detected for at least one predetermined supply frequency (fsp), said operating point being compared to a former operating point.
Claims7
A method for detecting a fault in a rotating field machine having a motor connected to a frequency converter, in which current components are analysed at the frequency converter in a flux-based, particularly rotor-flux-based, coordinate system, a flux-forming current component (ivekd) being subjected to a frequency analysis at the frequency converter in the flux-based, particularly rotor-flux-based, coordinate system, wherein a current operating point is detected at the frequency converter for at least one predetermined supply frequency (fsp), said operating point being compared to a former operating point stored in a reference memory;
- wherein at least one critical frequency (fk) is calculated and the frequency spectrum is analysed at this critical frequency (fk);
- and
- wherein the critical frequency (fk) of a stator fault is determined as
- fk=2·fsp
- and of a rotor winding fault as
- fk=2(fsp−n·p)
- where:
- fsp is the supply frequency,
- n is the rotor speed, and
- p is the number of pole pairs.
Dependencies are inferred from the claim text.