US4510399A
Expired / Lapsed
US
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Demodulator circuit for parallel AC power systems
Assignee: Sundstrand Corp
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Filing: 1982-10-07
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Granted: 1985-04-09
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Expires: 2002-10-07
Abstract
Abstract A demodulator circuit utilizes a switching demodulation technique to detect the real and reactive components of load current unbalance in a parallel source alternating current power system. A signal representing load current unbalance is selectively switched to a pair of output terminals in response to a series of pulse wave control signals which bear a phase relationship with the Thevenin equivalent voltage of one of the power sources such that the signal appearing at one of the output terminals represents the real load current component while the signal at the other output terminal represents the reactive load current component. The signals at these terminals are fed back to control the frequency and voltage magnitude of one of the power system sources to eliminate load current unbalance.
Inventors
- 👤 Donal E. Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:53
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/16
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
157 words
A demodulator circuit comprising: a first input terminal for receiving a first time varying electrical signal whose waveform is subject to variation; a second input terminal for receiving a first pulse wave control signal; means for switching said first time varying signal to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level, thereby producing a voltage on said first output terminal which is representative of the real component of said first time varying signal; a third input terminal for receiving a second pulse wave control signal being phase displaced from said first pulse wave control signal by 90°; and means for switching said first time varying signal to a second output terminal when said second pulse wave control signal is at a second predetermined voltage level, thereby producing a voltage on said second output terminal which is representative of the reactive component of said first time varying signal.
Claim 2
Dependent Claim
157 words
A demodulator circuit comprising: a first input terminal for receiving a first time varying electrical signal whose waveform is subject to variation; a second input terminal for receiving a first pulse wave control signal; means for switching said first time varying signal to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level, thereby producing a voltage on said first output terminal which is representative of the real component of said first time varying signal; a third input terminal for receiving a second pulse wave control signal being phase displaced from said first pulse wave control signal by 90°; and means for switching said first time varying signal to a second output terminal when said second pulse wave control signal is at a second predetermined voltage level, thereby producing a voltage on said second output terminal which is representative of the reactive component of said first time varying signal.
Claim 3
Dependent Claim
19 words
A demodulator as recited in claim 1, wherein said first and second pulse wave control signals are square waves.
Claim 4
Dependent Claim
30 words
A demodulator as recited in claim 1, wherein said means for switching said first time varying signal to said first and second output terminals comprises at least two analog switches.
Claim 5
Dependent Claim
93 words
A demodulator circuit as recited in claim 1, further comprising: a fourth input terminal for receiving a second time varying electrical signal which is equivalent to said first time varying electrical signal that has been displaced by 180°; means for switching said second time varying signal to said first output terminal when said first pulse wave control signal is at a third predetermined voltage level; and means for switching said second time varying signal to said second output terminal when said second pulse wave control signal is at a fourth predetermined voltage level.
Claim 6
Dependent Claim
48 words
A demodulator circuit as recited in claim 4, further comprising: a transformer having a center tapped secondary, wherein said first time varying electrical signal is derived from one half of said secondary and said second time varying electrical signal is derived from the other half of said secondary.
Claim 7
Dependent Claim
20 words
A demodulator circuit as recited in claim 4, wherein said first and second pulse wave control signals are square waves.
Claim 8
Dependent Claim
47 words
A demodulator circuit as recited in claim 4, wherein said means for switching said first time varying signal to said first and second output terminals and said means for switching said second time varying signal to said first and second output terminals each comprise an analog switch.
Claim 9
Dependent Claim
142 words
A demodulator circuit as recited in claim 1, further comprising: a fourth input terminal for receiving a second time varying electrical signal which is equivalent to said first time varying electrical signal that has been phase displaced by 180°; a fifth input terminal for receiving a third pulse wave control signal being phase displaced from said first pulse wave control signal by 180°; means for switching said second time varying signal to said first output terminal when said third pulse wave control signal is at a third predetermined voltage level; a sixth input terminal for receiving a fourth pulse wave control signal being phase displaced from said second pulse wave control signal by 180°; and means for switching said second time varying signal to said second output terminal when said fourth pulse wave control signal is at a fourth predetermined voltage level.
Claim 10
Dependent Claim
193 words
A parallel power system, comprising: at least two variable voltage, variable frequency power sources having outputs connected to a common bus; means for producing a first time varying electrical signal whose waveform is subject to variation in response to unbalanced current flowing out of said power sources; means for producing a first pulse wave control signal in phase with the Thevenin voltage of a first one of said power sources; means for switching said first time varying electrical signal to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; means for controlling the frequency of said first one of said power sources in response to the voltage on said first terminal; means for producing a second pulse wave control signal being phase displaced from said first pulse wave control signal by 90°; means for switching said first time varying electrical signal to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; and means for controlling the magnitude of the voltage of said first one of said power sources in response to the voltage on said second terminal.
Claim 11
Dependent Claim
193 words
A parallel power system, comprising: at least two variable voltage, variable frequency power sources having outputs connected to a common bus; means for producing a first time varying electrical signal whose waveform is subject to variation in response to unbalanced current flowing out of said power sources; means for producing a first pulse wave control signal in phase with the Thevenin voltage of a first one of said power sources; means for switching said first time varying electrical signal to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; means for controlling the frequency of said first one of said power sources in response to the voltage on said first terminal; means for producing a second pulse wave control signal being phase displaced from said first pulse wave control signal by 90°; means for switching said first time varying electrical signal to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; and means for controlling the magnitude of the voltage of said first one of said power sources in response to the voltage on said second terminal.
Claim 12
Dependent Claim
21 words
A parallel power system as recited in claim 9, wherein said first and second pulse wave control signals are square waves.
Claim 13
Dependent Claim
30 words
A parallel power system as recited in claim 9, wherein said means for switching said first time varying signal to said first and second terminals each comprise an analog switch.
Claim 14
Dependent Claim
18 words
A parallel power system as recited in claim 9, further comprising: a capacitor connected to said second terminal.
Claim 15
Dependent Claim
89 words
A parallel power system as recited in claim 9, further comprising: means for producing a second time varying electrical signal which is equivalent to said first time varying electrical signal that has been displaced by 180°; means for switching said second time varying signal to said first terminal when said first pulse wave control signal is at a third predetermined voltage level; and means for switching said second time varying signal to said second terminal when said second pulse wave control signal is at a fourth predetermined voltage level.
Claim 16
Dependent Claim
49 words
A parallel power system as recited in claim 13, further comprising: a transformer having a center tapped secondary, wherein said first time varying electrical signal is derived from one half of said secondary and said second time varying electrical signal is derived from the other half of said secondary.
Claim 17
Dependent Claim
21 words
A parallel power system as recited in claim 13, wherein said first and second pulse wave control signals are square waves.
Claim 18
Dependent Claim
48 words
A parallel power system as recited in claim 13, wherein said means for switching said first time varying signal to said first and second terminals and said means for switching said second time varying signal to said first and second terminals each comprise at least two analog switches.
Claim 19
Dependent Claim
131 words
A parallel power system as recited in claim 9, further comprising: means for producing a second time varying electrical signal which is equivalent to said first time varying electrical signal that has been displaced by 180°; means for producing a third pulse wave control signal being phase displaced from said first pulse wave control signal by 180°; means for switching said second time varying signal to said first terminal when said third pulse wave control signal is at a third predetermined voltage level; means for producing a fourth pulse wave control signal being phase displaced from said second pulse wave control signal by 180°; and means for switching said second time varying signal to said second terminal when said fourth pulse wave control signal is at a fourth predetermined voltage level.
Claim 20
Independent Claim
108 words
A method for demodulating a time varying electrical signal whose waveform is subject to variation, comprising the steps of: generating a first pulse wave control signal which is in phase with the real component of the signal being demodulated; switching the signal being demodulated to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; and switching the signal being demodulated to a second output terminal when said second pulse wave control signal is at a second predetermined voltage level.
Claim 21
Independent Claim
108 words
A method for demodulating a time varying electrical signal whose waveform is subject to variation, comprising the steps of: generating a first pulse wave control signal which is in phase with the real component of the signal being demodulated; switching the signal being demodulated to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; and switching the signal being demodulated to a second output terminal when said second pulse wave control signal is at a second predetermined voltage level.
Claim 22
Independent Claim
189 words
A method for demodulating a time varying electrical signal whose waveform is subject to variation, comprising the steps of: developing a first and second phase displaced signals having zero and 180° phase displacements respectively from the signal being demodulated; generating a first pulse wave control signal which is in phase with the real component of the signal being demodulated; switching the first of said phase displaced signals to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level; switching the second of said phase displaced signals to said first output terminal when said first pulse wave control signal is at a second predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second output terminal when said second pulse wave control signal is at a third predetermined voltage level; and switching the second one of said phase displaced signal to said second output terminal when said second pulse wave control signal is at a fourth predetermined voltage level.
Claim 23
Independent Claim
189 words
A method for demodulating a time varying electrical signal whose waveform is subject to variation, comprising the steps of: developing a first and second phase displaced signals having zero and 180° phase displacements respectively from the signal being demodulated; generating a first pulse wave control signal which is in phase with the real component of the signal being demodulated; switching the first of said phase displaced signals to a first output terminal when said first pulse wave control signal is at a first predetermined voltage level; switching the second of said phase displaced signals to said first output terminal when said first pulse wave control signal is at a second predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second output terminal when said second pulse wave control signal is at a third predetermined voltage level; and switching the second one of said phase displaced signal to said second output terminal when said second pulse wave control signal is at a fourth predetermined voltage level.
Claim 24
Independent Claim
157 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source in the power system being controlled; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching said time varying electrical signal to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching said time varying electrical signal to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
Claim 25
Independent Claim
157 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source in the power system being controlled; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching said time varying electrical signal to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching said time varying electrical signal to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
Claim 26
Independent Claim
234 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source in the power system being controlled; developing a first and second phase displaced signal having zero and 180° phase displacements respectively from said time varying electrical signal; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching the first of said phase displaced signals to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; switching the second of said phase displaced signals to said first terminal when said first pulse wave control signal is at a second predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second terminal when said second pulse wave control signal is at a third predetermined voltage level; switching the second of said phase displaced signals to said second terminal when said second pulse wave control signal is at a fourth predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
Claim 27
Independent Claim
234 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source in the power system being controlled; developing a first and second phase displaced signal having zero and 180° phase displacements respectively from said time varying electrical signal; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching the first of said phase displaced signals to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; switching the second of said phase displaced signals to said first terminal when said first pulse wave control signal is at a second predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second terminal when said second pulse wave control signal is at a third predetermined voltage level; switching the second of said phase displaced signals to said second terminal when said second pulse wave control signal is at a fourth predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
Claim 28
Independent Claim
268 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source; developing a first and second phase displaced signals having zero and 180° phase displacements respectively from said time varying electrical signal; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching the first of said phase displaced signals to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; generating a third pulse wave control signal which is phase displaced from said first pulse wave control signal by 180°; switching the second of said phase displaced signals to said first terminal when said third pulse wave control signal is at a third predetermined voltage level; generating a fourth pulse wave control signal which is phase displaced from said second pulse wave control signal by 180°; switching the second of said phase displaced signals to said second terminal when said fourth pulse wave control signal is at a fourth predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
Claim 29
Independent Claim
268 words
A method for controlling a parallel source power system, comprising the steps of: generating a time varying electrical signal proportional to unbalanced current flow from one power source; developing a first and second phase displaced signals having zero and 180° phase displacements respectively from said time varying electrical signal; generating a first pulse wave control signal which is in phase with the real component of said time varying electrical signal; switching the first of said phase displaced signals to a first terminal when said first pulse wave control signal is at a first predetermined voltage level; generating a second pulse wave control signal which is phase displaced from said first pulse wave control signal by 90°; switching the first of said phase displaced signals to a second terminal when said second pulse wave control signal is at a second predetermined voltage level; generating a third pulse wave control signal which is phase displaced from said first pulse wave control signal by 180°; switching the second of said phase displaced signals to said first terminal when said third pulse wave control signal is at a third predetermined voltage level; generating a fourth pulse wave control signal which is phase displaced from said second pulse wave control signal by 180°; switching the second of said phase displaced signals to said second terminal when said fourth pulse wave control signal is at a fourth predetermined voltage level; controlling the frequency of said power source in response to the voltage on said first terminal; and controlling the voltage magnitude of said power source in response to the voltage on said second terminal.
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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) | 1988-04-08 | 1988-10-08 | 1989-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-08 | 1992-10-08 | 1993-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-08 | 1996-10-08 | 1997-04-09 | $7700.00 | Window Closed / Lapsed |