Patent US6697759B2 successfully refreshed from Google Patents.
US6697759B2
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US
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Method of determining speed of rotation of a motor and a computer software product to carry out the method
Assignee: ABB Research Ltd Switzerland
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Filing: 2002-09-04
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Granted: 2004-02-24
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Expires: 2022-09-04
Abstract
Abstract The present invention relates to a method of determining speed of rotation of a motor. The method involves collecting samples with a measuring sensor at a sampling frequency, set on the basis of mechanical vibration of the motor, for the duration of a measurement period and storing the samples in the memory of a data carrier as measurement data of a fixed format. The speed of rotation of the motor is determined from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by means of a maximum likelihood estimate calculated by maximizing a maximum likelihood function adjusted to the measurement data, the speed of rotation being obtained from the frequency point where the maximum likelihood function obtains its maximum value.
Inventors
- 👤 Kari Saarinen
- 👤 Michal Orkisz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:15
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01M; G01M15/00; G01M15/04; G01M15/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
189 words
A method of determining speed of rotation of a motor ( 1 ), the method comprising connecting a measuring sensor ( 2 ) to the motor ( 1 ); determining the synchronous speed of the motor ( 1 ); setting the length of a measurement period (T); setting a sampling frequency (f s ); collecting samples (x[n]) with a measuring sensor ( 3 ) at the sampling frequency (f s ), set on the basis of mechanical vibration of the motor ( 1 ), for the duration of the measurement period (T); storing the samples (x[n]) in the memory of a data carrier ( 4 ) as measurement data of a fixed format, determining the speed of rotation of the motor ( 1 ) from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by applying a maximum likelihood estimate calculated by maximizing a maximum likelihood function (J) adjusted to the measurement data, the speed of rotation being obtained from a frequency point ( 13 f ) where the maximum likelihood function (J) obtains its maximum value ( 13 max ).
Claim 2
Independent Claim
189 words
A method of determining speed of rotation of a motor ( 1 ), the method comprising connecting a measuring sensor ( 2 ) to the motor ( 1 ); determining the synchronous speed of the motor ( 1 ); setting the length of a measurement period (T); setting a sampling frequency (f s ); collecting samples (x[n]) with a measuring sensor ( 3 ) at the sampling frequency (f s ), set on the basis of mechanical vibration of the motor ( 1 ), for the duration of the measurement period (T); storing the samples (x[n]) in the memory of a data carrier ( 4 ) as measurement data of a fixed format, determining the speed of rotation of the motor ( 1 ) from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by applying a maximum likelihood estimate calculated by maximizing a maximum likelihood function (J) adjusted to the measurement data, the speed of rotation being obtained from a frequency point ( 13 f ) where the maximum likelihood function (J) obtains its maximum value ( 13 max ).
Claim 3
Dependent Claim
33 words
A method according to claim 1 , wherein, before the speed of rotation is determined, the vibration signal is filtered in a bandpass filter to attenuate the interference that is in the signal.
Claim 4
Dependent Claim
101 words
A method according to claim 1 , wherein the maximum likelihood function (J) takes the following form J = ABS ( ∑ n = 0 N - 1 x [ n ] - j2πυ n ) , in which formula ABS=the absolute value of a complex number J=a maximum likelihood function to be maximized N=the number of samples n=the order number of a sample x[n]=an individual sample υ=the digital frequency of a periodic vibration signal, and υ= f/f s , in which formula f=the frequency of the periodic vibration signal f s =sampling frequency.
Claim 5
Dependent Claim
27 words
A method according to claim 1 , the wherein length of the measurement period (T) is at least 50 times the cycle length of the vibration signal.
Claim 6
Dependent Claim
32 words
A method according to claim 1 , t wherein he sampling frequency (f s ) is at least three times the synchronous speed (f n ) of the motor ( 1 ).
Claim 7
Dependent Claim
22 words
A method according to claim 1 wherein, the speed of rotation is determined using a maximum likelihood estimate of the time domain.
Claim 8
Dependent Claim
22 words
A method according to claim 1 , wherein the measuring sensor ( 3 ) is an acceleration sensor or a speed sensor.
Claim 9
Dependent Claim
137 words
A computer software product for determining speed of rotation of a motor, the product comprising a program code portion for collecting samples with a measuring sensor at a sampling frequency, set on the basis of mechanical vibration of the motor, for a duration of a measurement period; a program code portion for storing the samples in a memory of a data carrier as measurement data of a fixed format; a program code portion for determining the speed of rotation of the motor from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by applying a maximum likelihood estimate calculated by maximizing a maximum likelihood function adjusted to the measurement data, the speed of rotation being obtained from a frequency point where the maximum likelihood function obtains its maximum value.
Claim 10
Dependent Claim
137 words
A computer software product for determining speed of rotation of a motor, the product comprising a program code portion for collecting samples with a measuring sensor at a sampling frequency, set on the basis of mechanical vibration of the motor, for a duration of a measurement period; a program code portion for storing the samples in a memory of a data carrier as measurement data of a fixed format; a program code portion for determining the speed of rotation of the motor from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by applying a maximum likelihood estimate calculated by maximizing a maximum likelihood function adjusted to the measurement data, the speed of rotation being obtained from a frequency point where the maximum likelihood function obtains its maximum value.
References Cited (Backward Citations)
US5365787A
Cited
US5424636A
Cited
EP0632261A2
Cited
DE19600640A1
Cited
WO1999010715A1
Cited
US6085121A
Cited
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