US5187652A
Expired / Lapsed
US
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Turn-off circuit
Assignee: ASEA BROWN BOVER Ltd
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Filing: 1991-11-26
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Granted: 1993-02-16
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Expires: 2011-11-26
Abstract
Abstract In circuits with self-commutation such as, for example in inverters (4) for feeding an asynchronous machine (7), a short-time turn-off current impulse is taken from a turn-off capacitor (C1) of a turn-off or common turn-off circuit (3) for interrupting the thyristor current of the inverter. The turn-off circuit (3) connected to the direct-current side (8, 9) of the inverter (4) exhibits a first series circuit of the turn-off capacitor (C1) and a first electrical valve (T2, D2). In a branch in parallel with the turn-off capacitor (C1), a ring-around reactor (L1) with an inductance of 0.1 mH is connected in series with a second thyristor (T1). A further third thyristor (T3) is connected in antiparallel with the second thyristor (T1). A ring-around process initiated by the firing of the second thyristor (T1) is interrupted after a half period. After a freely selectable time, the third thyristor (T3) can be fired and the full resonance cycle can be concluded. As a result, the hold-off interval or minimum turn-off period for the thyristors can be achieved with a comparatively very small ring-around reactor (L1).
Inventors
- 👤 Peter Steimer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:37
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/5152; H02M5/00; H02M5/40; H02M5/42; H02M5/44; H02M5/443; H02M5/45; H02M5/4505; H02M7/53; H02M7/537; H02M7/5383; H02M7/53846; H02M7/53854
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
188 words
A turn-off circuit for a circuit having a self-commutated electrical valve comprising: a) a positive feed terminal and a negative feed terminal; a first series circuit including a turn-off capacitor and a first electrical valve, a first terminal of said turn-off capacitor being connected to said positive feed terminal and an anode of said first electrical valve being connected to a second terminal of said capacitor such that said first series circuit is connected directly to the positive and negative feed terminals; c) a second series circuit including an inductor and a controllable second electrical valve in a branch in parallel with the turn-off capacitor, a negative potential side of said second electrical valve being connected to the anode of the first electrical valve such that said turn-off capacitor and said negative potential side of said second electrical valve are connected to said negative feed terminal via said first electrical valve; and d) a controllable third electrical valve provided in a branch in parallel with the second electrical valve, a direction of current flow of the third electrical valve being opposite to that of the second electrical valve.
Claim 2
Dependent Claim
188 words
A turn-off circuit for a circuit having a self-commutated electrical valve comprising: a) a positive feed terminal and a negative feed terminal; a first series circuit including a turn-off capacitor and a first electrical valve, a first terminal of said turn-off capacitor being connected to said positive feed terminal and an anode of said first electrical valve being connected to a second terminal of said capacitor such that said first series circuit is connected directly to the positive and negative feed terminals; c) a second series circuit including an inductor and a controllable second electrical valve in a branch in parallel with the turn-off capacitor, a negative potential side of said second electrical valve being connected to the anode of the first electrical valve such that said turn-off capacitor and said negative potential side of said second electrical valve are connected to said negative feed terminal via said first electrical valve; and d) a controllable third electrical valve provided in a branch in parallel with the second electrical valve, a direction of current flow of the third electrical valve being opposite to that of the second electrical valve.
Claim 3
Dependent Claim
44 words
Turn-off circuit as claimed in claim 1, wherein the third electrical valve is connected in series with the first electrical valve, in such a manner that a cathode of the first electrical valve is operatively connected to an anode of the third electrical valve.
Claim 4
Dependent Claim
16 words
Turn-off circuit as claimed in claim 1, wherein the first to third electrical valves are thyristors.
Claim 5
Dependent Claim
16 words
Turn-off circuit as claimed in claim 2, wherein the first to third electrical valves are thyristors.
Claim 6
Dependent Claim
24 words
Turn-off circuit as claimed in claim 1, wherein the first electrical valve is a diode, and the second and third electrical valves are thyristors.
Claim 7
Dependent Claim
24 words
Turn-off circuit as claimed in claim 2, wherein the first electrical valve is a diode, and the second and third electrical valves are thyristors.
Claim 8
Dependent Claim
151 words
A turn-off circuit for an inverter having at least one forced-commutated electric valve which is connected to a direct voltage source via a link reactor, comprising: a) a first series circuit including a turn-off capacitor and a first electric valve, said first series circuit being connected directly parallel to the at least one forced-commutated electric valve and being connected directly parallel to the direct voltage source via the link reactor; b) a first branch parallel to the turn-off capacitor, said first branch including a second series circuit comprising at least one inductor and a controllable second electric valve, said turn-off capacitor and a negative potential side of the second electric valve being connected to an anode of the first electrical valve; and c) a second branch parallel to the second electric valve, said second branch including a controllable third electric valve which is connected antiparallel to the controllable second electric valve.
Claim 9
Dependent Claim
151 words
A turn-off circuit for an inverter having at least one forced-commutated electric valve which is connected to a direct voltage source via a link reactor, comprising: a) a first series circuit including a turn-off capacitor and a first electric valve, said first series circuit being connected directly parallel to the at least one forced-commutated electric valve and being connected directly parallel to the direct voltage source via the link reactor; b) a first branch parallel to the turn-off capacitor, said first branch including a second series circuit comprising at least one inductor and a controllable second electric valve, said turn-off capacitor and a negative potential side of the second electric valve being connected to an anode of the first electrical valve; and c) a second branch parallel to the second electric valve, said second branch including a controllable third electric valve which is connected antiparallel to the controllable second electric valve.
Claim 10
Dependent Claim
63 words
The turn-off circuit of claim 7, wherein the third electric valve is connected in series with the first valve such that a cathode of the first electric valve is connected directly to an anode of the third electric valve, and a cathode of the third electric valve is connected to an anode of the first electric valve via the controllable second electric valve.
References Cited (Backward Citations)
US3887862A
Cited
US4358811A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-02-16 | 1996-08-17 | 1997-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-02-16 | 2000-08-17 | 2001-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-02-16 | 2004-08-17 | 2005-02-16 | $7700.00 | Window Closed / Lapsed |