US4888676A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Damping circuit for turn-off valves
Assignee: BBC Brown Boveri AG Switzerland
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Filing: 1988-12-06
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Granted: 1989-12-19
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Expires: 2008-12-06
Abstract
Abstract Converter inverters, such as are used in the operation of alternating current machines, have turn-off reverse-conducting GTO thyristors in the bridge arms. Parallel to each GTO thyristor there is provided a series circuit composed of a turn-off load-shedding capacitor with a turn-off load-shedding diode. The common junction points of the respective turn-off load-shedding capacitors and diodes are connected in series to a choke via at least one capacitor load-shedding diode. The inductance of the choke is 2 to 3 times as large as the inductance of the circuit. The reverse-conducting GTO thyristors are directly connected in series, without the series connection of a choke. There thus arises a damping circuit of the GTO thyristor, which is very simple and, at the same time, feed back ring-around energy.
Inventors
- 👤 Urs Zurcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:14
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/5152; H02M7/5155
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
84 words
Damping circuit for at least two series-connected turn-off valves (a) a series circuit composed of a turn-off load-shedding capacitor and a turn-off load-shedding diode pole in the same direction as the turn-off valve being provided parallel to each turn-off valve, and (b) the common junction points of turn-off load-shedding capacitors and turn-off load-shedding diodes of respectively two series-connected turn-off valve being conductively interconnected in a unidirectional fashion via at least one capacitor load-shedding diode, wherein, (c) the turn-off valves are directly connected in series.
Claim 2
Dependent Claim
84 words
Damping circuit for at least two series-connected turn-off valves (a) a series circuit composed of a turn-off load-shedding capacitor and a turn-off load-shedding diode pole in the same direction as the turn-off valve being provided parallel to each turn-off valve, and (b) the common junction points of turn-off load-shedding capacitors and turn-off load-shedding diodes of respectively two series-connected turn-off valve being conductively interconnected in a unidirectional fashion via at least one capacitor load-shedding diode, wherein, (c) the turn-off valves are directly connected in series.
Claim 3
Dependent Claim
45 words
Damping circuit according to claim 1, wherein the common junction points of said turn-off load-shedding capacitor and said turn-off load-shedding diode of respectively two series-connected turn-off valves are conductively interconnected in series to an inductive reactance in an unidirectional fashion via the capacitor load-shedding diode.
Claim 4
Dependent Claim
48 words
Damping circuit according to claim 2, wherein the inductance of the inductive reactance is 1.5 to 5 times as large as the inductance of the circuit of a turn-off valve and of the series circuit parallel thereto composed of a turn-off load-shedding capacitor with a turn-off load-shedding diode.
Claim 5
Dependent Claim
91 words
Damping circuit according to claim 1, wherein (a) n turn-off valves are connected in series, n being an even integer greater than 4, (b) n/2 link capacitors are connected in series parallel to the n turn-off valves and (c) a common junction point of the mth and (m+1)th link capacitor is effectively connected to the common junction point of the mth and (m+1)th turn-off valve via a first diode, and to the common junction point of the (n/2+m)th and (n/2+m+1)th turn-off valve via a second diode, m=1 . . . (n/2-1).
Claim 6
Dependent Claim
13 words
Damping circuit according to claim 1 wherein the turn-off valves are GTO thyristors.
Claim 7
Dependent Claim
25 words
Damping circuit according to claim 1 wherein (a) a free-wheeling valve is connected antiparallel to each turn-off valve or (b) the turn-off valves are reverse-conducting.
Claim 8
Dependent Claim
48 words
The damping circuit of claim 2, wherein the inductance of the inductive reactance is 2 to 3 times as large as the inductance of the circuit of a turn-off valve and of the series circuit parallel thereto composed of a turn-off load-shedding capacitor with a turn-off load-shedding diode.
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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) | 1992-12-18 | 1993-06-19 | 1993-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-18 | 1997-06-19 | 1997-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-18 | 2001-06-19 | 2001-12-19 | $7700.00 | Window Closed / Lapsed |