US3634734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scr control for inductive power circuit
Assignee: FMC Corp
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Filing: 1969-07-16
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Granted: 1972-01-11
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Expires: 1989-07-16
Abstract
Abstract A control switch circuit for providing gate pulses to an SCR switch in an AC power circuit which circuit includes a variable inductive load. The control circuit includes a magnetic amplifier with one control winding energized by a fixed reference voltage or by a variable control signal and with a second, oppositely wound control winding energized through a feedback circuit the input of which is provided by a current transformer connection to the power circuit. The output of the magnetic amplifier is a series of pulses which are connected to the gate of the SCR and which are shaped so as to provide a steep, high-voltage leading edge for precise timing and for saturation of the gate junction of the SCR in a minimum time period.
Inventors
- 👤 Junius D Scott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:03
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/08; H02M1/081
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
295 words
A gate-triggering circuit for a semiconductor-controlled rectifier which is connected between an AC power source and an inductive DC load such as an electromagnetic feeder coil and which is adapted to switch to said load a predetermined portion of each positive half-cycle of applied AC power and to block from said load each negative half-cycle of applied AC power, said triggering circuit comprising a magnetic amplifier having first and second oppositely wound control windings for controlling the amount of reset of the magnetic core of the amplifier, said magnetic amplifier having its output connected to the gate of said controlled rectifier for applying triggering pulses thereto, means for sensing the magnitude of the DC current to said load, a feedback circuit for filtering the output of said current-sensing means and directing a DC feedback signal to the first control winding of said magnetic amplifier which is proportional to the magnitude of the load current, a control circuit for applying an external DC signal to the second control winding of said magnetic amplifier whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, a pulse-shaping circuit comprising a two-stage DC transistor amplifier with the output of the second stage being connected to said gate and with the input of the first stage being connected to the output of said magnetic amplifier, and a capacitor arranged between the output of said second stage and the input of the first stage of said DC amplifier for providing positive feedback whereby the transistors are rapidly driven into saturation upon the reception of an input pulse from said magnetic amplifier to thereby provide a squared pulse output to said gate.
Claim 2
Dependent Claim
295 words
A gate-triggering circuit for a semiconductor-controlled rectifier which is connected between an AC power source and an inductive DC load such as an electromagnetic feeder coil and which is adapted to switch to said load a predetermined portion of each positive half-cycle of applied AC power and to block from said load each negative half-cycle of applied AC power, said triggering circuit comprising a magnetic amplifier having first and second oppositely wound control windings for controlling the amount of reset of the magnetic core of the amplifier, said magnetic amplifier having its output connected to the gate of said controlled rectifier for applying triggering pulses thereto, means for sensing the magnitude of the DC current to said load, a feedback circuit for filtering the output of said current-sensing means and directing a DC feedback signal to the first control winding of said magnetic amplifier which is proportional to the magnitude of the load current, a control circuit for applying an external DC signal to the second control winding of said magnetic amplifier whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, a pulse-shaping circuit comprising a two-stage DC transistor amplifier with the output of the second stage being connected to said gate and with the input of the first stage being connected to the output of said magnetic amplifier, and a capacitor arranged between the output of said second stage and the input of the first stage of said DC amplifier for providing positive feedback whereby the transistors are rapidly driven into saturation upon the reception of an input pulse from said magnetic amplifier to thereby provide a squared pulse output to said gate.
Claim 3
Dependent Claim
39 words
A gate-triggering circuit for a semiconductor-controlled rectifier as set forth in claim 1 including a second capacitor and a resistor arranged in parallel and connected between said gate and the output of said second stage of said DC amplifier.
Claim 4
Dependent Claim
254 words
A power circuit for driving an inductive DC load such as an electromagnetic feeder coil from an AC power source comprising a semiconductor-controlled rectifier connected in series with said load for delivering a predetermined fraction of each positive half-cycle of applied power to said load and for blocking each negative half-cycle of applied power to said load, a magnetic amplifier driven from said power source and connected so as to supply gate triggering pulses to said controlled rectifier, a current transformer tap connected in series with said load and having an output which is proportional to the magnitude of the DC current to the load, a feedback circuit for rectifying the output of said current transformer and applying it to a first control winding on said magnetic amplifier, a second control winding of said magnetic amplifier being oppositely wound from said first control winding, a control circuit for applying an external DC signal to said second control winding whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, a pulse shaping circuit comprising a two-stage DC transistor amplifier having the input to the first stage connected to the output of said magnetic amplifier and the output of the second stage connected to the gate of said controlled rectifier, and positive feedback means connecting the output of said second stage with the input of said first stage for providing a squared pulse to said gate.
Claim 5
Dependent Claim
254 words
A power circuit for driving an inductive DC load such as an electromagnetic feeder coil from an AC power source comprising a semiconductor-controlled rectifier connected in series with said load for delivering a predetermined fraction of each positive half-cycle of applied power to said load and for blocking each negative half-cycle of applied power to said load, a magnetic amplifier driven from said power source and connected so as to supply gate triggering pulses to said controlled rectifier, a current transformer tap connected in series with said load and having an output which is proportional to the magnitude of the DC current to the load, a feedback circuit for rectifying the output of said current transformer and applying it to a first control winding on said magnetic amplifier, a second control winding of said magnetic amplifier being oppositely wound from said first control winding, a control circuit for applying an external DC signal to said second control winding whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, a pulse shaping circuit comprising a two-stage DC transistor amplifier having the input to the first stage connected to the output of said magnetic amplifier and the output of the second stage connected to the gate of said controlled rectifier, and positive feedback means connecting the output of said second stage with the input of said first stage for providing a squared pulse to said gate.
Claim 6
Dependent Claim
45 words
A power circuit as set forth in claim 3 including a parallel combination of a capacitor and a resistor serially connected between said gate and said output of said second stage of said DC amplifier for providing each pulse with a high-voltage steep leading edge.
Claim 7
Dependent Claim
90 words
A power circuit as set forth in claim 3 wherein the gate windings of said magnetic amplifier are provided with an AC voltage from said AC power source, and means for phase shifting said AC voltage input to the gate windings with respect to said AC power source so that said gate winding input leads said power source by an electrical angle of less that 90* whereby the positive half-cycles of the AC power source can be switched through said controlled rectifier for a maximum conduction angle of approximately 180*.
Claim 8
Dependent Claim
62 words
A poWer circuit as set forth in claim 3 wherein said control circuit for applying said external DC signal to said second control winding includes a current-limiting resistor connected in series with said second control winding and a capacitor connected in parallel with said second control winding and said resistor for the prevention of sudden increases in current to said inductive load.
Claim 9
Dependent Claim
82 words
A power circuit as set forth in claim 6, said control circuit further comprising rectifying means for receiving a fixed AC voltage and producing a variable DC output, zener diode-regulating means connected to the output of said rectifying means for fixing the peak magnitude of said variable DC voltage, and a control potentiometer connected to the output of said regulating means and across said capacitor, said potentiometer being adjustable to provide a predetermined magnitude of said variable DC voltage to said capacitor.
Claim 10
Dependent Claim
30 words
A power circuit as set forth in claim 6 wherein said control circuit is provided with input terminals connected across said capacitor for receiving a continuously variable external DC signal.
Claim 11
Dependent Claim
285 words
A gate-triggering circuit for a semiconductor-controlled rectifier which is connected between an AC power source and in inductive DC load such as an electromagnetic feeder coil and which is adapted to switch to said load a predetermined portion of each positive half-cycle of applied AC power and to block from aid load each negative half-cycle of applied AC power, said triggering circuit comprising a magnetic amplifier having first and second oppositely wound control windings for controlling the amount of reset of the magnetic core of the amplifier, said magnetic amplifier having its output connected to the gate of said controlled rectifier for applying triggering pulses thereto, means for sensing the magnitude of the DC current to said load, a feedback circuit for filtering the output of said current-sensing means and directing a DC feedback signal to the first control winding of said magnetic amplifier which is proportional to the magnitude of the load current, a control circuit for applying an external DC signal to the second control winding of said magnetic amplifier whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, said gate windings of said magnetic amplifier being provided with an AC voltage from said AC power source, and means for phase shifting the AC voltage input to the gate windings of said magnetic amplifier with respect to said AC power source so that said gate winding input leads said power source by an angle of less than 90* whereby the positive half-cycles of the AC power source can be switched through said controlled rectifier for a maximum conduction angle of approximately 180*.
Claim 12
Dependent Claim
285 words
A gate-triggering circuit for a semiconductor-controlled rectifier which is connected between an AC power source and in inductive DC load such as an electromagnetic feeder coil and which is adapted to switch to said load a predetermined portion of each positive half-cycle of applied AC power and to block from aid load each negative half-cycle of applied AC power, said triggering circuit comprising a magnetic amplifier having first and second oppositely wound control windings for controlling the amount of reset of the magnetic core of the amplifier, said magnetic amplifier having its output connected to the gate of said controlled rectifier for applying triggering pulses thereto, means for sensing the magnitude of the DC current to said load, a feedback circuit for filtering the output of said current-sensing means and directing a DC feedback signal to the first control winding of said magnetic amplifier which is proportional to the magnitude of the load current, a control circuit for applying an external DC signal to the second control winding of said magnetic amplifier whereby the timing of said pulses from said amplifier is determined by the magnitude of the differential control signal provided by the combination of said first and second control windings, said gate windings of said magnetic amplifier being provided with an AC voltage from said AC power source, and means for phase shifting the AC voltage input to the gate windings of said magnetic amplifier with respect to said AC power source so that said gate winding input leads said power source by an angle of less than 90* whereby the positive half-cycles of the AC power source can be switched through said controlled rectifier for a maximum conduction angle of approximately 180*.
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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) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |