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US4475074A
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Apparatus for determining the common frequency of two independently variable electrical a-c variables, especially in a rotating-field machine
Assignee: Siemens AG
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Filing: 1983-01-07
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Granted: 1984-10-02
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Expires: 2003-01-07
Abstract
Abstract An apparatus for determining the common frequency w of two independently variable a-c quantities is described. In a rotating-field machine, the flux, for instance, is described by two electrical a-c quantities which together determine the magnitude and direction of the field. The two a-c quantities are variable independently of each other and the instantaneous direction of the field is given by an angleα according to the relation a 1 /a 2 =cotanα, where a 1 and a 2 are the two a-c quantities. In order to determine the frequency of rotation w=dα/dt of the field from these quantities, the quantities a 1 and a 2 are each fed to smoothing stages and thence to a computing circuit, wherein the quotient (d 1 ·a 2 -d 2 ·a 1 )/(d 1 ·a 1 +d 2 ·a 2 ) proportional to the frequency is formed from a 1 and a 2 and the smoothed quantities d 1 and d 2 . The use of differentiators is thereby avoided, which would cause a phase error as well as difficulties when harmonics of the quantities a 1 and a 2 are present.
Inventors
- 👤 Leonhard Reng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:12
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/14; G; G01; G01R; G01R23/00; G01R31/00; G01R31/34; H02P27/00; H02P27/04; H02P27/045; H02P27/047
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
176 words
In an apparatus having two independently variable electrical a-c quantities a 1 and a 2 supplied as respective inputs for determining a common frequency w of the two electrical a-c quantities, wherein an angle quantity α variable with the common frequency w is related to the a-c quantitites a 1 and a 2 such that a 1 /a 2 =contan α, the improvement comprising: first smoothing stage means having said a-c quantity a 1 supplied as an input for producing a smoothed quantity d 1 ; second smoothing stage means having said a-c quantity a 2 supplied as an input for producing a smoothed quantity d 2 , said second smoothing stage means being substantially identical to said first smoothing stage means; computing means, having said a-c quantities a 1 and a 2 and said smoothed quantities d 1 and d 2 supplied as respective inputs, for generating, as an output, a quantity (d 1 ·a 2 -d 2 ·a 1 )/(d 1 ·a 1 +d 2 ·a 2 ) proportional to said common frequency w.
Claim 2
Dependent Claim
176 words
In an apparatus having two independently variable electrical a-c quantities a 1 and a 2 supplied as respective inputs for determining a common frequency w of the two electrical a-c quantities, wherein an angle quantity α variable with the common frequency w is related to the a-c quantitites a 1 and a 2 such that a 1 /a 2 =contan α, the improvement comprising: first smoothing stage means having said a-c quantity a 1 supplied as an input for producing a smoothed quantity d 1 ; second smoothing stage means having said a-c quantity a 2 supplied as an input for producing a smoothed quantity d 2 , said second smoothing stage means being substantially identical to said first smoothing stage means; computing means, having said a-c quantities a 1 and a 2 and said smoothed quantities d 1 and d 2 supplied as respective inputs, for generating, as an output, a quantity (d 1 ·a 2 -d 2 ·a 1 )/(d 1 ·a 1 +d 2 ·a 2 ) proportional to said common frequency w.
Claim 3
Dependent Claim
30 words
The improvement recited in claim 1 wherein said computing means comprises summing means, multiplying means and at least one dividing means for generating said quantity proportional to said common frequency.
Claim 4
Dependent Claim
169 words
The improvement recited in claim 1, wherein said computing means comprises: first multiplying means having said quantities a 1 and d 1 as inputs for forming the product d 1 ·a 1 ; second multiplying means having said quantities a 2 and d 2 as inputs for forming the product d 2 ·a 2 ; first summing means coupled to said first and second multiplying means for forming the quantity d 1 ·a 1 +d 2 ·a 2 ; third multiplying means having said quantities d 1 and a 2 as inputs for forming the product d 1 ·a 2 ; fourth multiplying means having said quantities d 2 and a 1 as inputs for forming the product d 2 ·a 1 ; second summing means coupled to said third and fourth multiplying means for forming the quantity d 1 ·a 2 -d 2 ·a 1 ; and dividing means coupled to said first and second summing means for forming the quotient ##EQU1## proportional to said common frequency w.
Claim 5
Dependent Claim
41 words
The improvement recited in claim 1, further comprising normalizing means, having said a-c quantities a 1 and a 2 as inputs, for forming, as outputs, the normalized a-c quantities ##EQU2## said outputs coupled to the inputs of said respective smoothing means.
Claim 6
Dependent Claim
68 words
The improvement recited in claim 1 in combination with a field-oriented control rotating-field machine drive, said machine drive including means for determining said a-c quantities a 1 and a 2 which together determine the magnitude and direction of the machine flux of a rotating-field machine, said means for determining having frequency dependent amplifying means controlled by said common frequency w coupled to the output of said computing means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-02 | 1988-04-02 | 1988-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-02 | 1992-04-02 | 1992-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-02 | 1996-04-02 | 1996-10-02 | $7700.00 | Window Closed / Lapsed |