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US3720866A
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Method and system for determination of rotor angle of synchromechanism
Assignee: Westinghouse Electric Corp
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Filing: 1972-02-02
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Granted: 1973-03-13
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Expires: 1992-02-02
Abstract
Abstract Synchromechanism outputs in alternating current (AC) waveform are processed by signal conditioning and integrating circuitry, converted from analog voltages to digital amplitude equivalents, and supplied as inputs to a digital processor. High accuracy in the conversion of synchro output to digital representation of synchro angle or position is achieved by a unique computation on the converted synchro output such that common forms of electrical noise which normally limit accuracy are canceled in the computation process. Further, techniques in signal integration and end-to-end circuitry calibration are employed in a compatible manner to enhance the inherent advantages of digital processing. The synchro to digital conversion scheme accommodates variations in signal processing to meet requirements of speed, accuracy and cost.
Inventors
- 👤 K Avellar
- 👤 J Buchanan
- 👤 E Higgins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:34
CPC Classifications
G; G08; G08C; G08C19/00; G08C19/38; G08C19/46; G08C19/48
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
208 words
For use with a synchromechanism having a rotor winding energized by a reference excitation voltage and stator windings of known geometry, a system for determination of the rotor angular position comprising: means for deriving from the synchromechanism two related output voltages corresponding to voltages induced in two stator windings, means for sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known, permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples, including noise and distortion voltage amplitudes common to the two related samples, means for processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is canceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 2
Dependent Claim
208 words
For use with a synchromechanism having a rotor winding energized by a reference excitation voltage and stator windings of known geometry, a system for determination of the rotor angular position comprising: means for deriving from the synchromechanism two related output voltages corresponding to voltages induced in two stator windings, means for sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known, permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples, including noise and distortion voltage amplitudes common to the two related samples, means for processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is canceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 3
Dependent Claim
208 words
For use with a synchromechanism having a rotor winding energized by a reference excitation voltage and stator windings of known geometry, a system for determination of the rotor angular position comprising: means for deriving from the synchromechanism two related output voltages corresponding to voltages induced in two stator windings, means for sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known, permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples, including noise and distortion voltage amplitudes common to the two related samples, means for processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is canceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 4
Dependent Claim
208 words
For use with a synchromechanism having a rotor winding energized by a reference excitation voltage and stator windings of known geometry, a system for determination of the rotor angular position comprising: means for deriving from the synchromechanism two related output voltages corresponding to voltages induced in two stator windings, means for sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known, permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples, including noise and distortion voltage amplitudes common to the two related samples, means for processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is canceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 5
Dependent Claim
37 words
A system as recited in claim 1 further comprising: analog to digital converter means for digitizing the samples of the output voltages, and said processing means comprises a digital processor for receiving the digitized output voltage samples.
Claim 6
Dependent Claim
53 words
A system as recited in claim 2 further comprising: switching means selectively operable to alternately select said samples for supply to said analog to digital converter, and a holding register for receiving digitized samples from said analog to digital converter for supply of said related digitized samples to said digital processor, for processing.
Claim 7
Dependent Claim
49 words
A system as recited in claim 1 wherein said sampling means comprises: integration means responsive to the output voltages to develop integrated values for the said samples thereof over a predetermined integration interval, and means responsive to the period of the reference excitation voltage to establish the integration interval.
Claim 8
Dependent Claim
72 words
A system as recited in claim 4 wherein there is further provided switching means associated with said integration means and selectively operated by said means responsive to the period of the reference eXcitation voltage normally to disable said integration means and thereby clear the results of the integration function thereof for prior samples and selectively to enable the integration means to effect integration of the output voltages during each successive integration interval.
Claim 9
Dependent Claim
76 words
A system as recited in claim 4 wherein there exist plural sets of two related output voltages respectively corresponding to plural sets of related stator windings, and wherein: said integration means includes two individual integrators respectively receiving the two output voltages of each set thereof, and there is further provided: input multiplexing switches controlled by said processing means for selecting the related output voltages of each set, in succession, for supply to the respectively corresponding integrators.
Claim 10
Dependent Claim
84 words
A system as recited in claim 6 wherein there is further provided: switching means associated with said integrators, an analog to digital converter, said switching means being controlled by said processing means for alternately selecting said integrated voltage samples from said integrators for supply to said analog to digital converter, and a holding register for receiving the digitized and integrated voltage samples from said analog to digital converter to afford simultaneous supply of said related digital samples to said digital processor for processing thereby.
Claim 11
Dependent Claim
24 words
A system as recited in claim 4 wherein said means responsive to the period of the reference excitation voltage comprises a zero crossing detector.
Claim 12
Dependent Claim
35 words
A system as recited in claim 8 wherein said zero crossing detector is responsive to the reference excitation voltage to define the integration interval to coincide with a half cycle of the reference excitation voltage.
Claim 13
Dependent Claim
45 words
A system as recited in claim 4 wherein there is further provided scaling amplifiers for receiving and scaling said output voltages for supplying scaled voltages to said integration means of said sampling means in accordance with an acceptable input voltage range of said integration means.
Claim 14
Dependent Claim
83 words
A system as recited in claim 1 wherein there is further provided: calibration means including a reference calibration voltage and selective switching means controlled by said processing means for periodically supplying the calibration voltage to said sampling means in lieu of said output voltages, and said processing means responds to the sample values derived from said periodic calibration voltages to correct for differences in amplification to which said output voltages from said stator windings are subjected prior to input to said processing means.
Claim 15
Independent Claim
194 words
A method for determining the rotor angular position of a synchromechanism including stator windings of known geometry and wherein the rotor winding is energized with a reference excitation voltage, comprising: selecting two output voltages from two selected stator windings, sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples including common noise and distortion voltage amplitudes common to the two samples, processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is caNceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 16
Independent Claim
194 words
A method for determining the rotor angular position of a synchromechanism including stator windings of known geometry and wherein the rotor winding is energized with a reference excitation voltage, comprising: selecting two output voltages from two selected stator windings, sampling the output voltages to derive related samples of the form X K sin ( Mu + ax) and Y K sin ( Mu + ay) where ax and ay are the known permanent angular relationships of the two stator windings relative to a reference, Mu is the rotor angle relative to that same reference, and K is a common amplitude factor for the related samples including common noise and distortion voltage amplitudes common to the two samples, processing the said related samples to determine the rotor angle Mu in accordance with one of: cos Mu Tc/(Tc2 + Ts2)1/2 (1) and sin Mu Ts/(Tc2 + Ts2)1/2 (2) where Tc X cos ay - Y cos ax, and Ts -X sin ay + Y sin ax and wherein the factor K is caNceled and the effects of noise and distortion voltage amplitudes included in the factor K correspondingly are eliminated from the value Mu thus determined.
Claim 17
Dependent Claim
30 words
The method of claim 12 wherein the sampling step further comprises integrating each of the input voltages over preselected, periodic time intervals as a function of the reference excitation voltage.
Claim 18
Dependent Claim
25 words
The method of claim 13 further comprising: digitizing the integrated sample values for each integration interval, and processing the digitized values of said related samples.
Claim 19
Dependent Claim
47 words
The method of claim 14 further comprising: alternately selecting the integrated sample values for each related set thereof for digitizing thereof by an analog to digital converter in a time shared relationship, and storing the digitized sample values of the related output samples for simultaneous processing thereof.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-12 | 1976-09-11 | 1977-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-12 | 1980-09-11 | 1981-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-12 | 1984-09-11 | 1985-03-13 | $7700.00 | Window Closed / Lapsed |