Patent US4507722A successfully refreshed from Google Patents.
US4507722A
Expired / Lapsed
US
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Method and apparatus for controlling the power factor of a resonant inverter
Assignee: Tocco Inc
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Filing: 1984-03-12
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Granted: 1985-03-26
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Expires: 2004-03-12
Abstract
Abstract A method and apparatus for controlling the frequency of a power inverter for converting D.C. current into A.C. current having a frequency controlled by gating signals, which apparatus and method includes a load voltage detector for deriving a voltage wave; a load current detector for deriving a current wave; a phase shifter to shift the phase of one of the waves by 90°; a multiplier to multiply the voltage and current waves; one with the other to produce a product; a reference signal for comparison with the product to create a control signal; and, a gating signal controller responding to the control signal.
Inventors
- 👤 Shashi B. Dewan
- 👤 Graham R. Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:27
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/525; H02M7/527; H02M7/529
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
109 words
A circuit for controlling the frequency of gating signals for the switching devices of a D.C. to A.C. inverter having an output to be connected across a load, said circuit comprising: means for detecting the load voltage to obtain a voltage wave; means for detecting the load current to obtain a current wave; means for shifting one of said waves by substantially 90°; means for multiplying said one wave and the other of said waves to produce the product thereof; means for comparing said product with a reference to produce a control signal; and means for adjusting the frequency of said gating signals in accordance with said control signal.
Claim 2
Dependent Claim
109 words
A circuit for controlling the frequency of gating signals for the switching devices of a D.C. to A.C. inverter having an output to be connected across a load, said circuit comprising: means for detecting the load voltage to obtain a voltage wave; means for detecting the load current to obtain a current wave; means for shifting one of said waves by substantially 90°; means for multiplying said one wave and the other of said waves to produce the product thereof; means for comparing said product with a reference to produce a control signal; and means for adjusting the frequency of said gating signals in accordance with said control signal.
Claim 3
Dependent Claim
14 words
A circuit as defined in claim 1 wherein said shifting means is an integrator.
Claim 4
Dependent Claim
14 words
A circuit as defined in claim 1 wherein said detected voltage wave is shifted.
Claim 5
Independent Claim
128 words
A method of controlling the frequency of gating signals for the switching devices of a D.C. to A.C. inverter having an output to be connected to a load, said method comprising the steps of: (a) integrating a detected load voltage wave to produce a wave that is phase shifted ninety degrees; (b) multiplying the integrated load voltage wave with a detected load current wave to produce an output wave; (c) using the deviation of the average value of the output wave from a reference level to produce a control signal indicative of the difference between the power factor of the load and unity power factor; (d) using said control signal to adjust the operating frequency of the gating signals to an inverter to produce a predetermined power factor.
Claim 6
Independent Claim
128 words
A method of controlling the frequency of gating signals for the switching devices of a D.C. to A.C. inverter having an output to be connected to a load, said method comprising the steps of: (a) integrating a detected load voltage wave to produce a wave that is phase shifted ninety degrees; (b) multiplying the integrated load voltage wave with a detected load current wave to produce an output wave; (c) using the deviation of the average value of the output wave from a reference level to produce a control signal indicative of the difference between the power factor of the load and unity power factor; (d) using said control signal to adjust the operating frequency of the gating signals to an inverter to produce a predetermined power factor.
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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) | 1988-03-25 | 1988-09-24 | 1989-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-25 | 1992-09-24 | 1993-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-25 | 1996-09-24 | 1997-03-26 | $7700.00 | Window Closed / Lapsed |