Self-powered, self-regulated, electronic ac control system

• US 4,504,778 A
• Filed: 07/15/1982
• Issued: 03/12/1985
• Est. Priority Date: 07/15/1982
• Status: Expired due to Fees

• Current Assignee: Electronic Systems International, Inc. (ACT Manufacturing, Inc.)
• Original Assignee: Electronic Systems International, Inc. (ACT Manufacturing, Inc.)
• Inventors: Evans, Wayne W.
• Primary Examiner(s): Beha, Jr., William H.
• Application Number:
  US06/398,325
• Time in Patent Office: 971 Days
• Field of Search: 323/300, 323/324, 323/321, 323/323, 323/238, 323/239, 307/252 B
• US Class Current: 323/323
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H05B 39/02 Switching on, e.g. with predetermined rate of increase of lighting current
• CPC Class Codes: H05B 39/08 by shifting phase of trigger voltage applied to gas-filled controlling tubes also in controlled semiconductor devices in converters H02M5/00; with regulation G05F1/44

Abstract

A system of controlling the operation of an AC load with a switch placed in series with the load, which switch is itself operated by dc control logic powered by power loss experienced by the switch which the logic controls. Numerous elements in the control system perform multiple functions allowing the control logic to remain alive during both the on and off mode of the switch without power being provided to the logic by separate conductors to the AC power source, such that the control system is completely self powered and self regulated by simply placing the system, with two wires, into a series loop with the AC power source and the load.

Claims

1. Apparatus for controlling the operation of a load, which load is provided by a circuit with alternating current from an AC power source, said apparatus comprising:

a bidirectional thyristor positioned in series with the load and the AC power source, said thyristor including a first main terminal, a second main terminal, and a gate terminal;

a first resistance element positioned in a parallel circuit in parallel with said thyristor between said first main terminal and said gate terminal;

second resistance element selectively shorted and unshorted out of and into said parallel circuit in series with said first resistance element and between said first main terminal and said gate terminal of said thyristor;

third resistance element positioned in said parallel circuit between said gate terminal and said second main terminal of said thyristor; and

control logic circuitry powered by power provided by the voltage drop across said thyristor, said control logic circuitry including means for shorting and unshorting said second resistance element out of and into said parallel circuit in series with said first resistance element, whereby unshorting of said second resistance element into said parallel circuit places said thyristor in a nonconducting mode and shorting of said second resistance element out of said parallel circuit places the thyristor in a current conducting mode, thus turning the load off and on, respectively.

2. Apparatus of claim 1, wherein said means for shorting and unshorting said second resistance element out of and into said parallel circuit comprises a first switch element in parallel with said second resistance element, and switch activating means for opening and closing said first switch element at predetermined, selectable intervals.

3. Apparatus of claim 1, further comprising a full-wave bridge rectifier positioned in said parallel circuit between said first main terminal and said gate terminal of said thyristor, said rectifier defining a unidirectional branch of unidirectional current, and a voltage regulator positioned in said unidirectional branch of said rectifier, wherein said second resistance element is positioned in said unidirectional branch in series with said voltage regulator.

4. Apparatus for providing power to a control logic circuitry, comprising:

AC power lead for connecting to an AC power source;

return lead for connecting to a load;

an AC switching device connecting between said power lead and said return lead, said AC switching device requiring the existence of a minimum voltage drop across said switching device before current can flow through said switching device between said power lead and said return lead;

triggering circuit connecting said power lead and said return lead in parallel with said AC switching device including means for developing a threshold voltage drop across said switching device at least equal to said minimum voltage drop; and

power circuit means associated with said triggering circuit for converting at least a portion of said threshold voltage drop across said switching device into the power required to drive a control logic circuitry while current is flowing through said switching device, said power circuit means comprising rectification means for providing a unidirectional current in a dc branch of said triggering circuit, a zener diode positioned in said dc branch, a capacitor positioned in said dc branch in parallel with said zener diode, and terminal means for connecting control logic circuitry to said dc branch in parallel with said zener diode and said capacitor; and

a diode positioned in said dc branch in series with the parallel combination of said zener diode, said capacitor and said terminal means, whereby said diode and said zener diode combine to clamp the unidirectional current at a desired value.

5. Apparatus for providing power to a control logic circuitry, comprising:

a bidirectional thyristor switching device for connecting in series between an AC power source and a load, said thyristor switching device including a first main terminal, a second main terminal and a gate terminal

a first resistor in parallel with said switching device between said first main terminal and said gate terminal;

a second resistor in parallel with said switching device between said gate terminal and said second main terminal;

a full wave bridge rectifier in series with said first resistor between said first resistor and said gate terminal, said bridge rectifier defining a unidirectional branch in a portion of the circuit between said first resistor and said gate terminal for providing unidirectional current, said unidirectional branch having a unidirectional output point and a logic ground reference point;

a zener diode positioned in said unidirectional branch in series with said first resistor;

a capacitor positioned in said unidirectional branch in parallel with said zener diode;

a light emitting diode positioned in said unidirectional branch in series with the parallel combination of said zener diode and said capacitor; and

terminal means for connecting control logic circuitry to said unidirectional branch, said terminal means including a first terminal for connecting the control logic circuity to the positive side of said zener diode and said capacitor, in parallel with said zener diode and said capacitor, and a second terminal for connecting the control logic circuitry to said logic ground reference point of said unidirectional branch.

6. A self powered, self regulated, electronic AC control apparatus, comprising:

AC power lead for connecting to an AC power source;

return lead for connecting to a load;

a bidirectional thyristor switching device connected between said power lead and said return lead, said thyristor switching device including first main terminal connected to said power lead, a second main terminal connected to said return lead, and a gate terminal;

a first resistor in parallel with said device between said first main terminal and said gate terminal;

a full-wave bridge rectifier in series with said first resister between said first resistor and said gate terminal, said bridge rectifier defining a unidirectional branch in a portion of the circuit between said first resistor and said gate terminal for providing unidirectional current;

a zener diode positioned in said unidirectional branch in series with said first resistor;

a capacitor positioned in said unidirectional branch in parallel with said zener diode; and

second resistor selectively switchable into and out of said unidirectional branch in series with said parallel combination of said zener diode and said capacitor;

control logic circuitry connected to said unidirectional branch to the positive side of said zener diode and said capacitor, in parallel with said zener diode and said capacitor, said control logic circuitry including switch means for selectively switching said second resistor in and out of said unidirectional branch.

7. Apparatus of claim 6, further comprising a light emitting diode positioned in said unidirectional branch in series with said zener diode and said capacitor.

8. Apparatus of claim 6, further comprising a third resistance element between said gate terminal and said second main terminal of said thyristor.

9. A self-powered, self-regulated, electronic AC control apparatus, comprising:

a bidirectional thyristor for connecting in series between an AC power source and a load, said thyristor including a first main terminal, a second main terminal and a gate terminal, said thyristor defining a current conducting mode during which current flows through said thyristor in sufficient amperage to operate the load and a current blocking mode during which substantially no current flows through said thyristor to operate the load, said thyristor requiring the existence of a trigger voltage across said gate terminal and said first main terminal before said thyristor enter the current conducting mode;

switching circuit connected in parallel with said thyristor for series connection between the AC power source and the load, said switching circuit including voltage means for developing voltage across said gate terminal and said first main terminal of said thyristor to place said thyristor in the current conducting mode, said switching circuit defining a load-on mode during which said voltage means develops said trigger voltage to place said thyristor in the current conducting mode supplying current to the load through said thyristor, and said switching circuit defining a load-off mode during which said trigger voltage is not developed across said gate terminal and said first main terminal of said thyristor by said voltage means and during which current flowing from said switching circuit to the load is insufficient to operate the load;

logic means associated with said switching circuit for alternately placing said switching circuit in said load-off mode and said load-on mode;

said switching circuit comprising power converting means for converting power from the AC power source into power for maintaining continuous operation of said logic means during both the load-off mode and load-on mode;

first multiple function means for translating AC signals from the AC power source to unidirectional signals which are to be filtered to DC signals to power said logic means, and for creating 120 cycle per second synchronizing pulses to be used in control logic timing, and for conducting an AC signal to the gate terminal of said thyristor;

second multiple function means for indicating the on/off operation of said switching circuit, and for clipping the synchronizing pulses created by said first multiple functions means for uniform amplitude timing pulses, and for conducting current to the logic means;

third multiple functions means for regulating the voltage supplied to said logic means, and for supplying a minimum voltage to said logic means; and

forth multiple function means for filtering the unidirectional signals from said first multiple function means to provide approximately DC signals to the logic means during the current blocking modes of said thyristor, and for providing charge to the logic means during the current conducting modes of said thyristor.

10. Apparatus for controlling the operation of a load, which load is provided by a circuit with alternating current from an AC power source, said apparatus comprising:

a bidirectional thyristor positioned in series with the load and the AC power source, said thyristor including a first main terminal, a second main terminal, and a gate terminal;

a first resistance element positioned in a parallel circuit in parallel with said thyristor between said first main terminal and said gate terminal;

a full-wave bridge rectifier positioned in said parallel circuit between said first main terminal and said gate terminal of said thyristor, said rectifier defining a unidirectional branch of unidirectional current;

a zener diode positioned in said unidirectional branch of said rectifier in series with said first resistor;

a second resistance element selectively switchable into and out of said unidirectional branch of said rectifier in series with said zener diode;

control logic circuitry powered by power provided by a portion of the voltage drop across said thyristor appearing in said unidirectional branch of said rectifier, said control logic circuitry including a first switch element in parallel with said second resistance element and switch activating means for opening and closing said switch element at predetermined selectable intervals; and

third resistance element positioned in the circuit between said gate terminal and said second main terminal of said thyristor.