Power-line communication system using pulse transmission on the AC line

• US 5,691,691 A
• Filed: 01/06/1997
• Issued: 11/25/1997
• Est. Priority Date: 01/06/1997
• Status: Expired due to Term

• Current Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Merwin, Jeffrey D., Konopka, John G.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): TONG, NINA C
• Application Number:
  US08/779,194
• Time in Patent Office: 323 Days
• Field of Search: 340/310.02, 340/310.01, 340/310.03, 340/310.04, 340/310.07, 340/310.08, 307/89, 307/90
• US Class Current: 375/259
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H04L 12/2816 Controlling appliance services of a home automation network by calling their functionalities arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station; in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom H04Q9/00
• CPC Class Codes: H04L 2012/2843 Mains power line

Abstract

A power-line communication system (10) for use with a conventional AC source (12) having a hot wire (14) and a neutral wire (16). The communication system (10) includes a pulse transmitter (16) and at least one receiver (18) connected downstream from the pulse transmitter (16). The pulse transmitter (16) is coupled between the hot wire (14) of the AC source (12) and either the neutral wire (16) of the AC source (12) or earth ground. Each receiver (14) is coupled to the AC source (12). The pulse transmitter (16) includes a control circuit (30) for controlling the conduction of a shunt circuit (32) and sends messages to the receivers (20) by inducing momentary pulses in the AC voltage supplied by the AC source (12). The shunt circuit (32) includes a power switch (52) and an energy clamp circuit for limiting the amplitude and the duration of the current through the power switch (52) and the pulse induced in the AC line voltage. Each receiver (18) detects the momentary pulses and translates a given sequence of pulses into its corresponding message. In a preferred embodiment, the pulse transmitter (16) is used to send control commands to one or more controllable electronic ballasts (22) for powering fluorescent lamps (24).

Claims

1. A power-line communication system for use with a conventional AC source having a hot wire and a neutral wire, the system comprising:

a pulse transmitter having a hot terminal and a reference terminal, the hot terminal being couplable to the hot wire of the AC source and the reference terminal being connected to one of (i) earth ground and (ii) the neutral wire of the AC source, an AC voltage being present between the hot wire and the neutral wire of the AC source, the AC voltage having a positive half cycle and a negative half cycle, the pulse transmitter including a shunt circuit coupled between the hot terminal and the reference terminal, and a control circuit for rendering the shunt circuit conductive and non-conductive, wherein when the shunt circuit is conductive a current having an amplitude and a duration flows from the hot terminal to the reference terminal, the shunt circuit including an energy clamp circuit for limiting the amplitude and the duration of the current, the current being of sufficient amplitude to cause a pulse in the AC voltage, wherein a predetermined sequential pattern of pulses in the AC voltage corresponds to a predetermined message; and

at least one receiver connected downstream from the pulse transmitter, the receiver having a hot connection and a neutral connection, the hot connection being couplable to the hot wire of the AC source and the neutral connection being couplable to the neutral wire of the AC source, the receiver being operable to detect pulses in the AC voltage and to translate a predetermined sequential pattern of pulses in the AC voltage into a corresponding predetermined message.

2. The system of claim 1, wherein each pulse represents a corresponding bit value, the corresponding bit value being dependent upon at least one of (i) the time of occurrence of the pulse in relation to when the AC voltage passes through zero and (ii) whether the pulse occurs during the positive half cycle or the negative half cycle of the AC voltage.

3. The system of claim 1, wherein the pulse transmitter further includes an interface for accepting a user message and is operable to translate a user message into a corresponding sequential pattern of pulses in the AC voltage.

4. The system of claim 1, wherein the pulse transmitter is operable to induce at least one pulse in at least one of (i) the positive half cycle of the AC voltage and (ii) the negative half cycle of the AC voltage.

5. The system of claim 1, wherein the duration of each pulse in the AC voltage is in the range of about 1 microsecond to about 100 microseconds.

6. The system of claim 1, wherein the pulse transmitter comprises:

the control circuit having a trigger output, a hot input, and a reference wire, the hot input being coupled to the hot terminal of the pulse transmitter, and the reference wire being connected to the reference terminal of the pulse transmitter;

the shunt circuit comprising;

a source of direct current having a positive output and a reference output, the reference output being connected to the reference terminal of the pulse transmitter;

a high frequency coupling capacitor coupled between the hot terminal and a first node;

a first series circuit coupled between the first node and the reference terminal, the first series circuit comprising a pulse energy limiting capacitor and a power switch coupled at a second node, the power switch having a first conduction terminal, a second conduction terminal, and a control terminal, the first conduction terminal being coupled to the second node and the second conduction terminal being coupled to the reference terminal of the pulse transmitter;

an energy clamp circuit coupled between the first node and the reference terminal, the energy clamp circuit comprising an energy clamp resistor, a first energy clamp zener diode, and a second energy clamp zener diode, the energy clamp resistor being coupled between the first node and a third node, the first and second energy clamp zener diodes each having an anode and a cathode, the anode of the first zener diode being coupled to the energy clamp resistor at the third node, the cathode of the first zener diode being coupled to the cathode of the second zener diode at a fourth node, and the anode of the second zener diode being coupled to the reference terminal;

a second series circuit coupled between a fifth node and the reference terminal, the second series circuit comprising a trigger energy storage capacitor and a pull-down resistor coupled at a sixth node, the sixth node being coupled to the control terminal of the power switch, the trigger energy storage capacitor being coupled between the fifth node and the sixth node, and the pull-down resistor being coupled between the sixth node and the reference terminal;

a trigger current limiting resistor coupled between the fifth node and the trigger output of the control circuit;

a bias current source resistor coupled between the fifth node and the positive output of the source of direct current; and

a discharge resistor coupled between the first node and the second node.

7. The system of claim 6, wherein the power switch comprises a triac.

8. The system of claim 1, wherein each receiver further includes an earth ground terminal connected to earth ground.

9. An energy control system for use with a conventional AC source having a hot wire and a neutral wire, the system comprising:

a pulse transmitter having a hot terminal and a reference terminal, the hot terminal being couplable to the hot wire of the AC source and the reference terminal being connected to one of (i) earth ground and (ii) the neutral wire of the AC source, an AC voltage being present between the hot wire and the neutral wire of the AC source, the pulse transmitter including a shunt circuit coupled between the hot terminal and the reference terminal, and a control circuit for rendering the shunt circuit conductive and non-conductive, wherein when the shunt circuit is conductive a current having an amplitude and a duration flows from the hot terminal to the reference terminal, the shunt circuit including an energy clamp circuit for limiting the amplitude and duration of the current, the current being of sufficient amplitude to cause a pulse in the AC voltage, wherein a predetermined sequential pattern of pulses in the AC voltage corresponds to a predetermined control command; and

at least one controllable load connected downstream from the pulse transmitter, the load having a hot connection and a neutral connection, the hot connection being couplable to the hot wire of the AC source and the neutral connection being couplable to the neutral wire of the AC source, the load including a receiver, the receiver being operable to detect pulses in the AC voltage and to translate a predetermined sequential pattern of pulses in the AC voltage into a corresponding predetermined control command to be executed by the load.

10. The system of claim 9, wherein each pulse represents a corresponding bit value, the corresponding bit value being dependent upon at least one of (i) the time of occurrence of the pulse in relation to when the AC voltage passes through zero and (ii) whether the pulse occurs during the positive half cycle or the negative half cycle of the AC voltage.

11. The system of claim 9, wherein the pulse transmitter further includes an interface for accepting user commands and is operable to translate a user command into a corresponding sequential pattern of pulses in the AC voltage.

12. The system of claim 9, wherein the pulse transmitter is operable to induce at least one pulse in at least one of (i) the positive half cycle of the AC voltage and (ii) the negative half cycle of the AC voltage.

13. The system of claim 9, wherein the duration of each pulse in the AC voltage is in the range of about 1 microsecond to about 100 microseconds.

14. The system of claim 9, wherein the pulse transmitter comprises:

the control circuit having a trigger output, a hot input, and a reference wire, the hot input being coupled to the hot terminal of the pulse transmitter, and the reference wire being connected to the reference terminal of the pulse transmitter;

the shunt circuit comprising;

a source of direct current having a positive output and a reference output, the reference output being connected to the reference terminal of the pulse transmitter;

a high frequency coupling capacitor coupled between the hot terminal and a first node;

a first series circuit coupled between the first node and the reference terminal, the first series circuit comprising a pulse energy limiting capacitor and a power switch coupled at a second node, the power switch having a first conduction terminal, a second conduction terminal, and a control terminal, the first conduction terminal being coupled to the second node, and the second conduction terminal being coupled to the reference terminal of the pulse transmitter;

an energy clamp circuit coupled between the first node and the reference terminal, the energy clamp circuit comprising an energy clamp resistor, a first energy clamp zener diode, and a second energy clamp zener diode, the energy clamp resistor being coupled between the first node and a third node, the first and second energy clamp zener diodes each having an anode and a cathode, the anode of the first zener diode being coupled to the energy clamp resistor at the third node, the cathode of the first zener diode being coupled to the cathode of the second zener diode at a fourth node, and the anode of the second zener diode being coupled to the reference terminal;

a second series circuit coupled between a fifth node and the reference terminal, the second series circuit comprising a trigger energy storage capacitor and a pull-down resistor coupled at a sixth node, the sixth node being coupled to the control terminal of the power switch, the trigger energy storage capacitor being coupled between the fifth node and the sixth node, and the pull-down resistor being coupled between the sixth node and the reference terminal;

a trigger current limiting resistor coupled between the fifth node and the trigger output of the control circuit;

a bias current source resistor coupled between the fifth node and the positive output of the source of direct current; and

a discharge resistor coupled between the first node and the second node.

15. The system of claim 14, wherein the power switch comprises a triac.

16. The system of claim 9, wherein each load further includes an earth ground terminal connected to earth ground.

17. The system of claim 16, wherein at least one controllable load comprises a controllable electronic ballast adapted to light at least one fluorescent lamp.

18. The system of claim 17, wherein the pulse transmitter and the controllable electronic ballasts are operable to turn the fluorescent lamps on and off.

19. The system of claim 17, wherein the pulse transmitter and the controllable electronic ballasts are operable to vary the illumination level of the fluorescent lamps.

20. An energy control system for use with a conventional AC source having a hot wire and a neutral wire, the system comprising:

a pulse transmitter having a hot terminal and a reference terminal, the hot terminal being coupled to the hot wire of the AC source and the reference terminal being connected to earth ground, an AC voltage being present between the hot wire and the neutral wire of the AC source, the AC voltage including a positive half-cycle and a negative half-cycle, the pulse transmitter including a shunt circuit coupled between the hot terminal and the reference terminal, and a control circuit for rendering the shunt circuit conductive and non-conductive, wherein when the shunt circuit is conductive a current having an amplitude and a duration flows from the hot terminal to the reference terminal, the shunt circuit including an energy clamp circuit for limiting the amplitude and the duration of the current, the current being of sufficient amplitude to cause a momentary pulse in the AC voltage, the duration of the pulse being in the range of about 1 microsecond to about 100 microseconds, the pulse transmitter being operable to induce at least one pulse in at least one of (i) the positive half cycle of the AC voltage and (ii) the negative half cycle of the AC voltage, each pulse representing a corresponding bit value, the corresponding bit value being dependent upon at least one of (i) the time of occurrence of the pulse in relation to when the AC voltage passes through zero and (ii) whether the pulse occurs in the positive half cycle or the negative half cycle of the AC voltage, wherein a predetermined sequential pattern of pulses in the AC voltage corresponds to a predetermined control command;

at least one controllable electronic ballast connected downstream from the pulse transmitter, the ballast being adapted to light at least one fluorescent lamp, the ballast having a hot connection, a neutral connection, and an earth ground connection, the hot connection being coupled to the hot wire of the AC source, the neutral connection being coupled to the neutral wire of the AC source, and the earth ground connection being connected to earth ground, the ballast including a receiver, the receiver being operable to detect pulses in the AC voltage and to translate a predetermined sequential pattern of pulses in the AC voltage into a corresponding predetermined control command to be executed by the ballast;

the pulse transmitter further including an interface for accepting user commands and being further operable to translate a user command into a corresponding sequential pattern of pulses in the AC voltage;

the control circuit having a trigger output, a hot input, and a reference wire, the hot input being coupled to the hot terminal of the pulse transmitter, and the reference wire being connected to the reference terminal of the pulse transmitter;

the shunt circuit comprising;

a source of direct current having a positive output and a reference output, the reference output being connected to the reference terminal of the pulse transmitter;

a high frequency coupling capacitor coupled between the hot terminal and a first node;

a first series circuit coupled between the first node and the reference terminal, the first series circuit comprising a pulse energy limiting capacitor and a power switch coupled at a second node, the power switch having a first conduction terminal, a second conduction terminal, and a control terminal, the first conduction terminal being coupled to the second node, and the second conduction terminal being coupled to the reference terminal of the pulse transmitter;

an energy clamp circuit coupled between the first node and the reference terminal, the energy clamp circuit comprising an energy clamp resistor, a first energy clamp zener diode, and a second energy clamp zener diode, the energy clamp resistor being coupled between the first node and a third node, the first and second energy clamp zener diodes each having an anode and a cathode, the anode of the first zener diode being coupled to the energy clamp resistor at the third node, the cathode of the first zener diode being coupled to the cathode of the second zener diode at a fourth node, and the anode of the second zener diode being coupled to the reference terminal;

a second series circuit coupled between a fifth node and the reference terminal, the second series circuit comprising a trigger energy storage capacitor and a pull-down resistor coupled at a sixth node, the sixth node being coupled to the control terminal of the power switch, the trigger energy storage capacitor being coupled between the fifth node and the sixth node, and the pull-down resistor being coupled between the sixth node and the reference terminal;

a trigger current limiting resistor coupled between the fifth node and the trigger output of the control circuit;

a bias current source resistor coupled between the fifth node and the positive output of the source of direct current; and

a discharge resistor coupled between the first node and the second node;

the power switch comprising a triac; and

the pulse transmitter and the controllable electronic ballasts being operable to vary the illumination level of the fluorescent lamps and to turn the fluorescent lamps on and off.