Fault Detection in Induction Motors Based on Current Signature Analysis

Patent metadata

Field	Value
Publication number	US-2016266207-A1
Application number	US-201514642956-A
Country	US
Kind code	A1
Filing date	Mar 10, 2015
Priority date	Mar 10, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A method detects faults during a steady state of an operation of an induction motor. The method measures, in a time domain, a signal of a current powering the induction motor with a fundamental frequency and determines, in a frequency domain, a set of frequencies with non-zero amplitudes, such that a reconstructed signal formed by the set of frequencies with non-zero amplitudes approximates the signal measured in the time domain. The determining includes a compressive sensing via searching within a subband including the fundamental frequency of the signal subject to condition of a sparsity of the signal in the frequency domain. The method detects a fault in the induction motor if the set of frequencies includes a fault frequency different from the fundamental frequency.

First claim

Claimed is:

1 . A method for detecting faults during a steady state of an operation of an induction motor, comprising:
measuring, in a time domain, a signal of a current powering the induction motor with a fundamental frequency; determining, in a frequency domain, a set of frequencies with non-zero amplitudes, such that a reconstructed signal formed by the set of frequencies with non-zero amplitudes approximates the signal measured in the time domain, wherein the determining includes a compressive sensing via searching within a subband including the fundamental frequency of the signal subject to condition of a sparsity of the signal in the frequency domain; and detecting a fault in the induction motor if the set of frequencies includes a fault frequency different from the fundamental frequency, wherein steps of the method are performed by a processor.

2 . The method of claim 1 , further comprising:
controlling a supply of the current to the induction motor based on an outcome of detecting the fault.

3 . The method of claim 1 , further comprising:
interrupting supplying the current in response to detecting the fault.

4 . The method of claim 1 , further comprising:
determining a type of the fault based on an amplitude of the pair, wherein the type includes one or combination of a partial broken bar and a number of broken bars.

5 . The method of claim 4 , wherein the type of the fault is the partial broken bar if the amplitude of the fault frequency is less than a threshold.

6 . The method of claim 4 , further comprising:
determining a set of thresholds, each threshold in the set corresponds to a value of the number of broken bars; and comparing the amplitude of the pair with the set of thresholds to determine the number of the broken bars.

7 . The method of claim 1 , wherein the measuring includes sampling the signal with a sampling rate of at least twice of the fundamental frequency of the signal, wherein the sampling is performed on a uniform grid to produce a set of samples for a grid of frequencies, and wherein the compressive sensing includes a high resolution off-the-grid compressive sensing including a searching for a frequency between adjacent samples on the grid of frequencies.

8 . The method of claim 1 , wherein the compressive sensing comprises:
searching for the set of frequencies with non-zero amplitudes using a gradient search with atomic norm constraints representing the sparsity of the signal.

9 . The method of claim 1 , wherein the reconstructed signal is determined based on measuring the signal for a period of time less than one second.

10 . A system for operating an induction motor having a stator and rotor bars, comprising:
a power supply for powering the stator of the induction motor with a stator current having a fundamental frequency; a sensor for measuring, in a time domain, a signal of a stator current powering the induction motor, wherein the measuring includes sampling the signal for a period of time during a steady state of the operation of the induction motor with a sampling rate of at least twice of a fundamental frequency of the stator current; a processor for determining, in a frequency domain, a set of frequencies with non-zero amplitudes, such that a reconstructed signal formed by the frequencies with corresponding amplitudes approximates the signal measured in the time domain, wherein the determining includes searching within a subband including the fundamental frequency subject to condition of a sparsity of the signal in the frequency domain, and; a user interface for signaling the fault, if the set of frequencies includes a fault frequency approaching the dominant frequency.

11 . The system of claim 10 , wherein the processor compares comparing the amplitude of the fault frequency with a threshold to determine a type of the fault, and wherein the user interface renders the type.

12 . The system of claim 10 , wherein the reconstructed signal is determined based on measuring the signal for a period of time less than one second.

13 . The system of claim 10 , wherein the processor commands the power supply to interrupt supplying the current in response to detecting the fault.

14 . The system of claim 10 , wherein the sensor samples the signal on a uniform grid with a sampling rate of at least twice of the fundamental frequency of the signal to produce a set of samples for a grid of frequencies, and wherein the compressive sensing includes a high resolution off-the-grid compressive sensing including a searching for a frequency between adjacent samples on the grid of frequencies.

15 . The system of claim 10 , wherein the compressive sensing uses a gradient search with atomic norm constraints representing the sparsity of the signal.

Assignees

• Mitsubishi Electric Res Laboratories Inc

Inventors

• Liu Dehong

Classifications

• H02H7/0833

  for electric motors with control arrangements · CPC title

• H02H7/0854

  responsive to rate of change of current, couple or speed, e.g. anti-kickback protection (H02H7/0851 takes precedence) · CPC title

• H02H3/46

  responsive to frequency deviations · CPC title

• G01R31/343

  in operation · CPC title

• H02H7/08

  for dynamo-electric motors · CPC title