Patent US4969081A successfully refreshed from Google Patents.
US4969081A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inverter switch current sensor with shoot-through current limiting
Assignee: Sundstrand Corp
•
Filing: 1989-01-09
•
Granted: 1990-11-06
•
Expires: 2009-01-09
Abstract
Abstract The problem of sensing current through inverter switches is solved by a current transformer which has windings connected with the flyback diodes to demagnetize or reset the current transformer core. Size and weight of the transformer are minimized while avoiding a buildup of flux which would saturate the core.
Inventors
- 👤 Sampat S. Shekhawat
- 👤 Chai-Nam Ng
- 👤 P. John Dhyanchand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:06
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/40; H02M1/38; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/538
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
152 words
In a DC to AC inverter having a DC source, first and second alternately conducting switches connecting the source with an AC load and first and second flyback diodes, one connected in shunt with each switch to conduct current in the opposite sense to the shunt switch, an inverter switch current sensor, comprising: a current transformer having a core of magnetic material; first and second primary windings on said core, each connected in series with one of said switches and poled so that current through each switch establishes flux of the same sense in said core; third and fourth primary windings on said core, each connected in series with one of said flyback diodes and poled so that the flyback current establishes flux in the core of the sense opposite the switch current flux; and a secondary winding on said core for developing an output signal representing the current through said switches.
Claim 2
Dependent Claim
152 words
In a DC to AC inverter having a DC source, first and second alternately conducting switches connecting the source with an AC load and first and second flyback diodes, one connected in shunt with each switch to conduct current in the opposite sense to the shunt switch, an inverter switch current sensor, comprising: a current transformer having a core of magnetic material; first and second primary windings on said core, each connected in series with one of said switches and poled so that current through each switch establishes flux of the same sense in said core; third and fourth primary windings on said core, each connected in series with one of said flyback diodes and poled so that the flyback current establishes flux in the core of the sense opposite the switch current flux; and a secondary winding on said core for developing an output signal representing the current through said switches.
Claim 3
Dependent Claim
56 words
The inverter switch current sensor of claim 1 in which said inverter switches are subject to a shoot-through condition in which both switches conduct at the same time, the flyback currents reducing the remanent flux in the transformer core from the inverter switch currents so that the transformer core does not saturate in a shoot-through condition.
References Cited (Backward Citations)
US1971207A
Cited
US3308370A
Cited
US4002963A
Cited
USRE31840E
Cited
US4198595A
Cited
JPS5980164A
Cited
US4609832A
Cited
US4542440A
Cited
US4584635A
Cited
US4636929A
Cited
SU1365307A1
Cited
US4717994A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-11-05 | 1994-05-07 | 1994-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-05 | 1998-05-07 | 1998-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-05 | 2002-05-07 | 2002-11-06 | $7700.00 | Window Closed / Lapsed |