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Patent US4694387A successfully refreshed from Google Patents.
US4694387A
Expired / Lapsed
US
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Inductive devices
Assignee: Northrop Grumman Innovation Systems LLC
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Filing: 1987-01-08
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Granted: 1987-09-15
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Expires: 2007-01-08
Abstract
Abstract An inductive device composed of a bead (10) of magnetic material, such as ferrite, has an aperture through which an electrical conductor (13) is adapted to pass and a reset winding (14) wound thereon and connected to a source of constant current. The constant reset current resets the bead of magnetic material so that the maximum volt-second absorbtion capability of the bead is available for preventing destructively high current spikes from flowing through the electrical conductor. The inductive device is advantageously used in the d.c. supply of the power transistors (101 and 102) of an inverter (100) to protect the transistors from current surges due to the simultaneous conduction of the transistors.
Inventors
- 👤 Charles S. Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:48
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/02; H02H9/021
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
90 words
An inductive device for protecting one or more transistors in a power supply composed of a bead of magnetic material, said bead being formed with an axial aperture through which an electrical conductor electrically connected to electrodes of the transistors is adapted to pass, and a reset winding wound on said bead and connected to a source of constant current for resetting said inductive device so that the maximum volt-second absorbtion capability of said inductive device is available for preventing destructively high current spikes from flowing through said electrical conductor.
Claim 2
Dependent Claim
90 words
An inductive device for protecting one or more transistors in a power supply composed of a bead of magnetic material, said bead being formed with an axial aperture through which an electrical conductor electrically connected to electrodes of the transistors is adapted to pass, and a reset winding wound on said bead and connected to a source of constant current for resetting said inductive device so that the maximum volt-second absorbtion capability of said inductive device is available for preventing destructively high current spikes from flowing through said electrical conductor.
Claim 3
Dependent Claim
32 words
An inductive device as recited in claim 1 wherein said source of constant current includes a current limiting resistor and a source of d.c. voltage connected in series with said reset winding.
Claim 4
Dependent Claim
32 words
An inductive device as recited in claim 2 wherein said current limiting resistor and said source of d.c. voltage are connected to one or more other reset windings of similar inductive devices.
Claim 5
Dependent Claim
128 words
An inverter circuit comprising: a pair of power transistors; a power transformer having a primary winding and a secondary winding, said primary winding being connected to said power transistors and having a center tap; a load connected to said secondary winding; a source of d.c. current connected by an electrical conductor to said center tap; and an inductive device composed of a bead of magnetic material having an aperture through which said electrical conductor passes, and a reset winding wound on said bead and connected to a second source of d.c. current for resetting said inductive device so that the maximum volt-second absorbtion capability of said inductiYe device is available for preventing destructively high current spikes from flowing through said electrical conductor to said pair of power transistors.
Claim 6
Dependent Claim
128 words
An inverter circuit comprising: a pair of power transistors; a power transformer having a primary winding and a secondary winding, said primary winding being connected to said power transistors and having a center tap; a load connected to said secondary winding; a source of d.c. current connected by an electrical conductor to said center tap; and an inductive device composed of a bead of magnetic material having an aperture through which said electrical conductor passes, and a reset winding wound on said bead and connected to a second source of d.c. current for resetting said inductive device so that the maximum volt-second absorbtion capability of said inductiYe device is available for preventing destructively high current spikes from flowing through said electrical conductor to said pair of power transistors.
Claim 7
Dependent Claim
32 words
The inverter circuit recited in claim 4 wherein said second source of d.c. current includes a current limiting resistor and a source of d.c. voltage connected in series with said reset winding.
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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) | 1990-09-14 | 1991-03-16 | 1991-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-09-14 | 1995-03-16 | 1995-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-09-14 | 1999-03-16 | 1999-09-15 | $7700.00 | Window Closed / Lapsed |