US3733537A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for limiting instantaneous inverter current
Assignee: Westinghouse Electric Corp
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Filing: 1970-08-17
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Granted: 1973-05-15
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Expires: 1990-08-17
Abstract
Abstract The invention relates to a technique for limiting the peak transient currents in the power switches of an inverter wherein a current control circuit compares the current flow in the power switches of the inverter to a reference value and provides protective ON-OFF control of the power switches to prevent overload of the power switches. In the event the current flow through a power switch exceeds a predetermined value, the current control circuit overrides the main power switch ON-OFF control circuit and generates an inhibit signal which turns the power switch off for a period of time required to allow the current magnitude to decrease a predetermined amount at which time the current control circuit inhibit signal is removed and the main power switch ON-OFF control circuit resumes control of the power switch conduction.
Inventors
- 👤 A Kernick
- 👤 G Ernsberger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:22
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/5387; H02M7/53871; H02H; H02H7/00; H02H7/10; H02H7/12; H02H7/122; H02H7/1227
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
313 words
In a dc to ac electrical inverter circuit including first and second ON-OFF conduction control power switch means for developing an ac load current, the combination of, a first circuit means for providing alternate ON-OFF conduction control of said first and second conduction control power switch means, second circuit means operatively connected to said inverter circuit for monitoring the current flow through each of said first and second conduction control power switching means while in an ON state established by said first circuit means and developing an output signal representative of the magnitude of said current, said second circuit means including a current transformer means having a primary winding operatively connected in said inverter circuit, said current flow through said first and second conduction control switch means passing through said primary winding, and a secondary Winding, third circuit means for generating a reference signal, a fourth circuit means operatively connected to said secondary winding for developing said output signal in the form of a first voltage signal corresponding to the current flow through said first conduction controlled power switch means and a second voltage signal corresponding to the current flow through said second conduction controlled power switch means, and a current control circuit means operatively connected to said fourth circuit means for comparing said output signals of said fourth circuit means with said reference signal and generating an inhibit signal when a predetermined relationship exists between the magnitude of said output signals and the magnitude of said reference signal indicative of the excessive current flow through the ON power switch means, said inhibit signal being applied to said first circuit means to override the ON-OFF conduction control of the ON power switch means and turning said ON power switch means OFF until the magnitude of said current decreases to a predetermined value at which time said first circuit means resumes ON-OFF conduction control.
Claim 2
Dependent Claim
313 words
In a dc to ac electrical inverter circuit including first and second ON-OFF conduction control power switch means for developing an ac load current, the combination of, a first circuit means for providing alternate ON-OFF conduction control of said first and second conduction control power switch means, second circuit means operatively connected to said inverter circuit for monitoring the current flow through each of said first and second conduction control power switching means while in an ON state established by said first circuit means and developing an output signal representative of the magnitude of said current, said second circuit means including a current transformer means having a primary winding operatively connected in said inverter circuit, said current flow through said first and second conduction control switch means passing through said primary winding, and a secondary Winding, third circuit means for generating a reference signal, a fourth circuit means operatively connected to said secondary winding for developing said output signal in the form of a first voltage signal corresponding to the current flow through said first conduction controlled power switch means and a second voltage signal corresponding to the current flow through said second conduction controlled power switch means, and a current control circuit means operatively connected to said fourth circuit means for comparing said output signals of said fourth circuit means with said reference signal and generating an inhibit signal when a predetermined relationship exists between the magnitude of said output signals and the magnitude of said reference signal indicative of the excessive current flow through the ON power switch means, said inhibit signal being applied to said first circuit means to override the ON-OFF conduction control of the ON power switch means and turning said ON power switch means OFF until the magnitude of said current decreases to a predetermined value at which time said first circuit means resumes ON-OFF conduction control.
Claim 3
Dependent Claim
202 words
In a dc to ac electrical inverter circuit as claimed in claim 1 wherein said third circuit includes a dc voltage source and said reference signal is a dc voltage signal, and said current control means includes a first and second comparator means, each having first and second inputs, and an output, said reference signal being supplied to said first inputs of said first and second comparator circuit means, said first voltage signal of said fourth circuit means being supplied to the second input of said first comparator circuit means and said second voltage signal of said fourth circuit means being supplied to the second input of said second comparator circuit means, a first inhibit signal generating circuit operatively connected to said output of first comparator circuit means, and a second inhibit signal generating circuit operatively connected to said output of said second comparator circuit means, said first and second inhibit signal generating circuits being activated to generate inhibit signals in response to outputs of said first and second comparator circuit means corresponding to input conditions in which the magnitude of the voltage signals supplied to said second inputs exceeds the magnitude of the reference voltage signal supplied to said first inputs.
Claim 4
Dependent Claim
57 words
In a dc to ac electrical inverter circuit as claimed in claim 1 including a fifth circuit means for reducing the magnitude of said reference signal by a predetermined amount in response to the generating of said inhibit signal, the magnitude of said reference signal being restored to its initial value when said inhibit signal is terminated.
Claim 5
Dependent Claim
97 words
In a dc to ac electrical inverter circuit as claimed in claim 1 wherein said current transformer includes a first and second primary winding and a first and second core for coupling said first and second primary windings to said center tap secondary windings, said first and second voltage signals developed by said fourth circuit means corresponding to the current flow through the first and second primary windings respectively, said fourth circuit means including impedance circuit means for alternately resetting the individual primary winding during the inactive half cycles of their respective conduction controlled power switch means.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |