US3573508A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thyristor switch circuit
Assignee: AT&T Inc
•
Filing: 1968-09-27
•
Granted: 1971-04-06
•
Expires: 1988-09-27
Abstract
Abstract Heretofore, when a thyristor switch circuit has employed a resonant circuit, including a series-connected inductor and capacitor, for producing a cycle of ringing current which is used for turning off the thyristor, the minimum pulse width that could be obtained was usually greater than twice the recovery time of the thyristor. It has now been discovered that an approximately 50 percent reduction in this minimum pulse width can be effected by connecting a diode in series with the inductor-capacitor combination and by placing a saturable reactor in shunt across the serially connected diode and inductor. The diode is so poled as to prevent the initial discharge current produced by the capacitor from flowing through the inductor and forces this current to flow through the saturable reactor. Since the saturable reactor is biased to present a low inductive impedance to the first half-cycle of ringing current, it reduces the duration of this first half-cycle to a very short period of time. This provides a substantially greater ratio of turnoff time to pulse width and thereby produces a much narrower pulse for a given turnoff time.
Inventors
- 👤 William B Harris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:25
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/72; H03K17/73
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
275 words
A switch circuit adapted for generating a pulse of electric energy, said switch circuit comprising: a source of electric power; a normally nonconductive thyristor having anode and cathode terminals; a utilization circuit coupling said source of electric power to said anode terminal; starting means adapted for triggering said thyristor for rendering it conductive whereby a pulse is generated across said utilization circuit; said starting means including a gate terminal connected to said thyristor and adapted to receive electric energy for triggering said thyristor, and a resonant turnoff circuit adapted for producing one cycle of ringing current for turning off said thyristor for effecting the termination of the generation of said pulse and for limiting the duration of the width of said pulse to an extent of time that is less than the duration of said one cycle of ringing current; said turnoff circuit having one side connected to both said anode terminal and to said utilization circuit and having another side connected to said cathode terminal; said turnoff circuit including a serially connected inductor and capacitor; said one cycle of ringing current having a first half-cycle and a second half-cycle; said switch circuit being characterized in that it further comprises reducing means for rendering the duration of said first half-cycle of ringing current substantially shorter than the duration of said second half-cycle of ringing current for thereby reducing the width of said pulse; said reducing means comprising a shunt path connected across said inductor; said shunt path having a saturable reactor connected therein; and said reducing means further comprising blocking means for blocking the flow of said first half-cycle of ringing current through said inductor.
Claim 2
Dependent Claim
275 words
A switch circuit adapted for generating a pulse of electric energy, said switch circuit comprising: a source of electric power; a normally nonconductive thyristor having anode and cathode terminals; a utilization circuit coupling said source of electric power to said anode terminal; starting means adapted for triggering said thyristor for rendering it conductive whereby a pulse is generated across said utilization circuit; said starting means including a gate terminal connected to said thyristor and adapted to receive electric energy for triggering said thyristor, and a resonant turnoff circuit adapted for producing one cycle of ringing current for turning off said thyristor for effecting the termination of the generation of said pulse and for limiting the duration of the width of said pulse to an extent of time that is less than the duration of said one cycle of ringing current; said turnoff circuit having one side connected to both said anode terminal and to said utilization circuit and having another side connected to said cathode terminal; said turnoff circuit including a serially connected inductor and capacitor; said one cycle of ringing current having a first half-cycle and a second half-cycle; said switch circuit being characterized in that it further comprises reducing means for rendering the duration of said first half-cycle of ringing current substantially shorter than the duration of said second half-cycle of ringing current for thereby reducing the width of said pulse; said reducing means comprising a shunt path connected across said inductor; said shunt path having a saturable reactor connected therein; and said reducing means further comprising blocking means for blocking the flow of said first half-cycle of ringing current through said inductor.
Claim 3
Dependent Claim
70 words
A switch circuit in accordance with claim 1 wherein said blocking means include a diode having an anode and a cathode, and wherein said blocking means further include circuit means for connecting said anode of said diode to one end of said saturable reactor, and additional circuit means for connecting said cathode of said diode through said inductor to said capacitor and also to another end of said saturable reactor.
Claim 4
Dependent Claim
188 words
A switch circuit adapted for generating a pulse of electric energy, said switch circuit comprising: a source of electric power; a normally nonconductive thyristor having anode and cathode terminals; a utilization circuit coupling said source of electric power to said anode terminal; starting means adapted for triggering said thyristor for rendering it conductive whereby a pulse is generated across said utilization circuit; said starting means including a gate terminal connected to said thyristor and adapted to receive electric energy for triggering said thyrisTor, and a turnoff circuit adapted for turning off said thyristor for effecting the termination of the generation of said pulse; said turnoff circuit having one side connected to said anode terminal and another side connected to said cathode terminal; said switch circuit being characterized in that it further comprises means for reducing the width of said pulse; and said means including a pulse forming network comprising a chain of essentially similar circuits each including a capacitor and an inductor, a saturable reactor having a plurality of taps, and circuit means for connecting each of said taps to a respectively different one of said similar circuits.
Claim 5
Dependent Claim
188 words
A switch circuit adapted for generating a pulse of electric energy, said switch circuit comprising: a source of electric power; a normally nonconductive thyristor having anode and cathode terminals; a utilization circuit coupling said source of electric power to said anode terminal; starting means adapted for triggering said thyristor for rendering it conductive whereby a pulse is generated across said utilization circuit; said starting means including a gate terminal connected to said thyristor and adapted to receive electric energy for triggering said thyrisTor, and a turnoff circuit adapted for turning off said thyristor for effecting the termination of the generation of said pulse; said turnoff circuit having one side connected to said anode terminal and another side connected to said cathode terminal; said switch circuit being characterized in that it further comprises means for reducing the width of said pulse; and said means including a pulse forming network comprising a chain of essentially similar circuits each including a capacitor and an inductor, a saturable reactor having a plurality of taps, and circuit means for connecting each of said taps to a respectively different one of said similar circuits.
Claim 6
Dependent Claim
49 words
A switch circuit in accordance with claim 3 and further comprising a diode having an anode and a cathode, circuit means for connecting said anode of said diode to said tapped reactor, and additional circuit means for connecting said cathode of said diode to said chain of similar circuits.
Claim 7
Dependent Claim
260 words
A switch circuit having a thyristor adapted for generating a pulse of electric energy: said switch circuit comprising a resonant turnoff circuit adapted for producing one cycle of ringing current for turning off said thyristor for effecting the termination of the generation of said pulse and for limiting the duration of the width of said pulse to an extent of time that is less than the duration of said one cycle of ringing current; said one cycle of ringing current comprising a first half-cycle and a second half-cycle having a trailing end; said turnoff circuit including a capacitor and a discharge path for said capacitor; said discharge path comprising an inductor connected in series with said capacitor; said switch circuit being characterized in that it includes reducing means for rendering the duration of said first half-cycle of ringing current substantially shorter than the duration of said second half-cycle of ringing current for reducing the on-off time interval of said thyristor and for thereby effecting a reduction in the width of said pulse; said reducing means comprising an alternative discharge path for said capacitor; said alternative discharge path including a saturable reactor connected in series with said capacitor and in parallel to said inductor; blocking means for blocking said discharge path through said inductor only during said first half-cycle of said ringing current; said saturable reactor having a core, and resetting means for automatically resetting said core of said reactor when said pulse is terminated; and said resetting means comprising the trailing end of said second half-cycle of said ringing current.
Claim 8
Dependent Claim
260 words
A switch circuit having a thyristor adapted for generating a pulse of electric energy: said switch circuit comprising a resonant turnoff circuit adapted for producing one cycle of ringing current for turning off said thyristor for effecting the termination of the generation of said pulse and for limiting the duration of the width of said pulse to an extent of time that is less than the duration of said one cycle of ringing current; said one cycle of ringing current comprising a first half-cycle and a second half-cycle having a trailing end; said turnoff circuit including a capacitor and a discharge path for said capacitor; said discharge path comprising an inductor connected in series with said capacitor; said switch circuit being characterized in that it includes reducing means for rendering the duration of said first half-cycle of ringing current substantially shorter than the duration of said second half-cycle of ringing current for reducing the on-off time interval of said thyristor and for thereby effecting a reduction in the width of said pulse; said reducing means comprising an alternative discharge path for said capacitor; said alternative discharge path including a saturable reactor connected in series with said capacitor and in parallel to said inductor; blocking means for blocking said discharge path through said inductor only during said first half-cycle of said ringing current; said saturable reactor having a core, and resetting means for automatically resetting said core of said reactor when said pulse is terminated; and said resetting means comprising the trailing end of said second half-cycle of said ringing current.
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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |