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

Claim 10:
11. An abnormality diagnosis system for diagnosing an abnormality in an electric motor, the system comprising:
a power conversion device configured to acquire and transmit a current waveform and a driving frequency of the electric motor driven by the power conversion device;
an abnormality diagnosis device that includes
a data acquisition circuit to acquire the current waveform and the driving frequency of the electric motor,
an operation pattern storage which stores a combination of an effective value of the current waveform and the driving frequency that are acquired at an identical first time by the data acquisition circuit, 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,
a data determination circuit to determine whether or not an effective value of the current waveform and the driving frequency as a diagnosis target that are acquired at an identical second time by the data acquisition circuit match the combination of the effective value of the current waveform and the driving frequency stored in the operation pattern storage,
an analyzer circuit to perform frequency analysis for the current waveform determined to be matched by the data determination circuit, to extract sideband waves, and calculate a spectrum intensity of the sideband waves,
an abnormality diagnosis circuit to make 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,
a learning table configured to store 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,
the learning table is further configured to store 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

the operation pattern storage stores 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, wherein
the operation pattern storage stores a combination of the effective value of the current waveform and the driving frequency that are acquired at a predetermined number of identical times by the data acquisition circuit,
the abnormality diagnosis device further configured to acquire the current waveform and the driving frequency acquired by the power conversion device; and
the system further comprising a monitoring device configured to output at least one of an indication and an alarm on the basis of a result of diagnosis by the abnormality diagnosis device.