US3582685A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zero crossover firing of thyristor means
Assignee: Honeywell Inc
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Filing: 1969-04-29
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Granted: 1971-06-01
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Expires: 1989-04-29
Abstract
Abstract The firing of an alternating current energized triac is controlled by a unijunction transistor. Both the base-to-base voltage and the triggering voltage of the unijunction transistor are supplied and controlled by a power supply which is synchronized to the alternating current source, such that the triac fires at near zero crossover of the alternating current. The firing is delayed, to occur approximately 3* after zero crossover, to insure latching current flow through the triac.
Inventors
- 👤 Lester N Bolmgren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:20
CPC Classifications
H; H02; H02M; H02M5/00; H02M5/02; H02M5/04; H02M5/22; H02M5/25; H02M5/257; H02M5/2573
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
219 words
In a control apparatus for zero crossover firing a thyristor means which is adapted to be connected to an alternating current source; the apparatus having a unijunction transistor with two base electrodes and an emitter electrode, a capacitor connEcted to said emitter electrode and adapted to be charged to a given voltage only upon the occurrence of a condition, and output means connected to one of said base electrodes and effective to produce an output to fire the thyristor means upon said capacitor discharging through a circuit which includes said emitter electrode and said one base electrode; the improvement comprising; synchronizing means having an input connected to be energized by the alternating current source and having an output voltage consisting of voltage pulses of a limited time period which occur at approximately zero crossover of the alternating current source, gating means having an input connected to be controlled by the output voltage of said synchronizing means and having an output connected in circuit with said capacitor to allow said capacitor to charge to said given voltage only during said limited time period, and means for applying said voltage pulses of limited time period to the other of said base electrodes of said unijunction transistor to prevent firing of said unijunction transistor until the end of said limited time period.
Claim 2
Dependent Claim
219 words
In a control apparatus for zero crossover firing a thyristor means which is adapted to be connected to an alternating current source; the apparatus having a unijunction transistor with two base electrodes and an emitter electrode, a capacitor connEcted to said emitter electrode and adapted to be charged to a given voltage only upon the occurrence of a condition, and output means connected to one of said base electrodes and effective to produce an output to fire the thyristor means upon said capacitor discharging through a circuit which includes said emitter electrode and said one base electrode; the improvement comprising; synchronizing means having an input connected to be energized by the alternating current source and having an output voltage consisting of voltage pulses of a limited time period which occur at approximately zero crossover of the alternating current source, gating means having an input connected to be controlled by the output voltage of said synchronizing means and having an output connected in circuit with said capacitor to allow said capacitor to charge to said given voltage only during said limited time period, and means for applying said voltage pulses of limited time period to the other of said base electrodes of said unijunction transistor to prevent firing of said unijunction transistor until the end of said limited time period.
Claim 3
Dependent Claim
35 words
Control apparatus as defined in claim 1 wherein said gating means includes controllable normally open switch means responsive to the output voltage waveform of said synchronizing means and closed only during said limited time period.
Claim 4
Dependent Claim
67 words
Control apparatus as defined in claim 2, including a source of charging voltage for said capacitor, wherein said switch means is a normally nonconductive transistor whose output electrodes connect said source of charging voltage in circuit with said capacitor and whose input electrode is connected to be controlled by the output voltage of said synchronizing means to render said transistor conductive only during said limited time period.
Claim 5
Dependent Claim
117 words
Control apparatus as defined in claim 3, wherein the input of said gating means comprises a voltage divider connected to be energized by the output voltage of said synchronizing means, wherein one of the output electrodes of said transistor is directly connected to said capacitor, wherein said transistor input electrode is connected to a low-voltage terminal of said voltage divider which is substantially equal in magnitude to said given voltage to thereby clamp the maximum charge of said capacitor at said given voltage, and wherein said means for applying said voltage pulses of limited time period to the other of said base electrodes of said unijunction transistor is connected to a high-voltage terminal of said voltage divider.
Claim 6
Dependent Claim
58 words
Control apparatus as defined in claim 1 wherein said synchronizing means includes; a direct current voltage source of a high magnitude, and controllable switch means connected to be controlled by the alternating current source and responsive to zero crossover of the alternating current source and connected to said source of direct current voltage for providing said output voltage.
Claim 7
Dependent Claim
121 words
Control apparatus as defined in claim 5 further comprising; a source of charging voltage for said capacitor, a voltage divider connected to be energized by said synchronizing means, wherein said gating means includes a normally nonconductive transistor having output electrodes connecting said source of charging voltage to said capacitor, and having an input electrode connected to a terminal of said voltage divider whose voltage magnitude is substantially equal to said given voltage to thereby clamp the maximum voltage charge of said capacitor at said given level, and wherein said means for applying said voltage pulses of limited time period to the other of said base electrodes of said unijunction transistor is connected to a higher voltage terminal of said voltage divider.
Claim 8
Dependent Claim
130 words
Control apparatus as defined in claim 5 wherein said controllable switch means includes; a first transistor having a pair of output electrodes, one of which is connected to said direct current source, and having an input electrode, a seCond transistor having a pair of output electrodes, one of which is connected to the input of electrode of said first transistor, and having an input electrode, full wave rectification means adapted to be energized by the alternating current source, circuit means including diode means connecting the other output electrode and the input electrode of said second transistor to said full wave rectification means in a manner to render said second transistor nonconductive for said limited time period, and wherein the other output electrode of said first transistor provides said output voltage.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |