Patent ID: 11953555
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 4:
5. An abnormality diagnosis method for diagnosing an abnormality in an electric motor, the method comprising:
acquiring data of a current waveform and a driving frequency of the electric motor driven by a power conversion device;
storing a combination of an effective value of the current waveform and the driving frequency that are acquired at an identical time in the data acquisition, the effective value of the current waveform being a square root of a value obtained by averaging a square of an instantaneous value of the current waveform over one cycle of the current waveform;
determining whether or not an effective value of the current waveform and the driving frequency as a diagnosis target that are acquired at an identical time in the data acquisition match the combination of the effective value of the current waveform and the driving frequency stored in the storing step;
performing frequency analysis for the current waveform determined to be matched in the data determination, to extract sideband waves, and calculate a spectrum intensity of the sideband waves;
making a diagnosis that abnormality has occurred in the electric motor, when the spectrum intensity of the sideband waves is equal to or greater than a threshold;
storing a plurality of learning combinations, each of the plurality of learning combinations includes the effective value of the current waveform and the driving frequency that are acquired at the identical time, the identical time being different for each of the plurality of learning combinations,
storing for each of the plurality of learning combinations, a number of times an identical learning combination having a same effective value of the current waveform, and a same driving frequency is acquired; and
storing one of the learning combinations as the combination of the effective value of the current waveform and the driving frequency that are acquired at the identical time only when the number of times of the learning combination is equal to or greater than a predetermined setting value.