Method, system, and computer-readable medium for sensorless measurement of induction machine rotor bar pass frequency
First Claim
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1. A method comprising:
- (a) sampling a current waveform of an induction machine to obtain sampled points;
(b) characterizing the sampled current over a selected first time window to obtain characterized points;
(c) subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points;
(d) obtaining a frequency spectrum representative of the residual signal over a selected second time window; and
(e) identifying a rotor bar pass frequency from the frequency spectrum.
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Abstract
A method comprises: sampling a current waveform of an induction machine to obtain sampled points; characterizing the sampled current over a selected first time window to obtain characterized points; subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points; obtaining a frequency spectrum representative of the residual signal over a selected second time window; and identifying a rotor bar pass frequency from the frequency spectrum. The method is typically carried out by a system comprising a computer, a computer-readable medium, or combinations thereof.
10 Citations
52 Claims
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1. A method comprising:
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(a) sampling a current waveform of an induction machine to obtain sampled points;
(b) characterizing the sampled current over a selected first time window to obtain characterized points;
(c) subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points;
(d) obtaining a frequency spectrum representative of the residual signal over a selected second time window; and
(e) identifying a rotor bar pass frequency from the frequency spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
(f) obtaining an induction machine speed from the rotor bar pass frequency, wherein (f) comprises obtaining induction machine speed estimates from each of the at least two significant side bands and averaging the induction machine speed estimates to obtain the induction machine speed.
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16. A method for sensorless measurement of induction machine (22) speed, the method comprising:
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(a) sampling a current waveform of the induction machine at a sampling frequency higher than a fundamental frequency of the induction machine to obtain sampled points;
(b) characterizing the sampled current over a selected first time window comprising a multiple of a fundamental period of the induction machine to obtain characterized points;
(c) subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points;
(d) obtaining a frequency spectrum representative of the residual signal over a selected second time window, wherein a beginning of the second time window is defined by a selected point;
(e) multiplying an approximate speed by the number of rotor bars of the machine to obtain an approximate bar pass frequency;
(f) obtaining at least one significant side band of the approximate bar pass frequency; and
(g) obtaining a rotor bar pass frequency from the at least one significant side band. (h) obtaining an induction machine speed from the rotor bar pass frequency. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A system comprising a computer configured for:
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(a) sampling a current waveform of an induction machine to obtain sampled points;
(b) characterizing the sampled current over a selected first time window to obtain characterized points;
(c) subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points;
(d) obtaining a frequency spectrum representative of the residual signal over a selected second time window; and
(e) identifying a rotor bar pass frequency from the frequency spectrum. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A computer-readable medium storing computer instructions for instructing a computer, the computer instructions comprising:
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(a) sampling a current waveform of an induction machine to obtain sampled points;
(b) characterizing the sampled current over a selected first time window to obtain characterized points;
(c) subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points;
(d) obtaining a frequency spectrum representative of the residual signal over a selected second time window; and
(e) identifying a rotor bar pass frequency from the frequency spectrum. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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Specification