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Patent US3614596A successfully refreshed from Google Patents.
US3614596A
Expired / Lapsed
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Controlled rectifier firing circuit
Assignee: Allen Bradley Co LLC
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Filing: 1970-02-06
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Granted: 1971-10-19
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Expires: 1990-02-06
Abstract
Abstract A summing circuit generates a DC command signal with magnitude proportional to the desired power to be conducted by a power SCR in a motor circuit. A unijunction transistor phase shift circuit receives the command signal and translates its magnitude to a firing angle by connecting the base circuit to an AC reference signal source and the emitter to a capacitor charged by the command signal and the AC reference signal. A sensitive SCR connected to the AC source is fired by the unijunction transistor to charge a capacitor of an oscillator, the output of which is amplified and transformer coupled to the gate of the power SCR.
Inventors
- 👤 David E Ford Jr
- 👤 Richard W Waltz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:03
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/08; H02M1/081; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/292; H02P7/295
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
167 words
A firing circuit for a controlled rectifier comprising the combination of a command signal source generating a command signal of varying magnitude; a reference signal source generating a reference signal of desired frequency and phase; a phase shift circuit including a timing capacitor connected to said command signal source to be charged by said command signal, and a first switching device connected to said reference signal and to said timing capacitor responsive to a predetermined charge level on said timing capacitor; a pulse-forming circuit containing a second switching device with a control element connected to said first switching device in said phase shift circuit to transmit a pulse of electrical energy when said first switching device discharges said capacitor; and a pulse-firing circuit containing an oscillator with an oscillator capacitor and an output-coupling means to transmit a train of firing signals responsive to a charge on said oscillator capacitor, said oscillator capacitor being connected to said pulse-forming circuit to be charged by said pulse of electrical energy.
Claim 2
Dependent Claim
167 words
A firing circuit for a controlled rectifier comprising the combination of a command signal source generating a command signal of varying magnitude; a reference signal source generating a reference signal of desired frequency and phase; a phase shift circuit including a timing capacitor connected to said command signal source to be charged by said command signal, and a first switching device connected to said reference signal and to said timing capacitor responsive to a predetermined charge level on said timing capacitor; a pulse-forming circuit containing a second switching device with a control element connected to said first switching device in said phase shift circuit to transmit a pulse of electrical energy when said first switching device discharges said capacitor; and a pulse-firing circuit containing an oscillator with an oscillator capacitor and an output-coupling means to transmit a train of firing signals responsive to a charge on said oscillator capacitor, said oscillator capacitor being connected to said pulse-forming circuit to be charged by said pulse of electrical energy.
Claim 3
Dependent Claim
69 words
A firing circuit for a controlled rectifier as set forth in claim 1 wherein said first switching device is a unijunction transistor with its base circuit connected to said reference signal source, said timing capacitor is also connected to be charged by said reference signal and is connected to an emitter of said unijunction transistor, and a zener diode is connected across said base circuit of said unijunction transistor.
Claim 4
Dependent Claim
65 words
A firing circuit for a controlled rectifier as set forth in claim 2 wherein said reference signal source includes an input terminal connected to receive an AC signal and a restorer capacitor and blocking diode connected in series to said terminal to insert a DC level in said AC signal to make said reference signal asymmetrical with a positive portion of more than 180* duration.
Claim 5
Dependent Claim
73 words
A firing circuit for a controlled rectifier as set forth in claim 1 wherein said second switching device is an SCR with its anode-cathode circuit connected to said reference signal source and its gate connected to said controLled current valve of said phase shift circuit to be fired thereby; and said oscillator capacitor in said pulse-firing circuit is connected to said anode-to-cathode circuit of said SCR to be charged when said SCR conducts.
Claim 6
Dependent Claim
113 words
A firing circuit for a controlled rectifier as set forth in claim 1 wherein said oscillator in said pulse-firing circuit includes a unijunction transistor with an emitter and a base-one and a base-two, said emitter being connected to said oscillator capacitor; and said pulse-firing circuit includes a DC power source and an amplifier transistor with a base and a collector-emitter circuit, said DC power source being connected to said base-two of said unijunction transistor and to said collector-emitter circuit of said amplifier transistor, and said base of said amplifier transistor is connected to said base-one of said unijunction transistor, and said output-coupling means is connected to said collector-emitter circuit of said amplifier transistor.
Claim 7
Dependent Claim
67 words
A firing circuit for a controlled rectifier as set forth in claim 3 wherein said pulse-forming circuit includes a zener diode connected across said blocking diode in said reference signal source, an SCR with a gate connected to said base circuit of said unijunction transistor in said phase shift circuit and an anode connected to said reference signal source and a cathode connected to said zener diode.
Claim 8
Dependent Claim
130 words
A firing circuit for a controlled rectifier as set forth in claim 6 wherein said oscillator includes a unijunction transistor with an emitter connected to said oscillator capacitor and a base circuit; said oscillator capacitor is connected to said anode of said SCR in said pulse-forming circuit to be charged when said SCR conducts; said pulse-firing circuit includes an input terminal connected to a DC source and to said base circuit of said unijunction transistor, and an amplifier transistor with a collector-emitter circuit connected to said input terminal and with a base connected to said base circuit of said unijunction transistor to be controlled by emitter-to-base conductivity of said unijunction transistor; and said output-coupling means is a transformer with a primary connected to said collector-emitter circuit of said amplifier transistor.
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) | 1974-10-18 | 1975-04-19 | 1975-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-18 | 1979-04-19 | 1979-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-18 | 1983-04-19 | 1983-10-19 | $7700.00 | Window Closed / Lapsed |