Controllable-load circuit for use with a load control device

Patent metadata

Field	Value
Publication number	US-9220133-B2
Application number	US-95007910-A
Country	US
Kind code	B2
Filing date	Nov 19, 2010
Priority date	Nov 20, 2009
Publication date	Dec 22, 2015
Grant date	Dec 22, 2015

Abstract

A load control device for controlling the amount of power delivered from an AC power source to an electrical load is operable to conduct enough current through a thyristor of a connected dimmer switch to exceed rated latching and holding currents of the thyristor. The load control device comprises a controllable-load circuit operable to conduct a controllable-load current through the thyristor of the dimmer switch. The load control device disables the controllable-load circuit when the phase-control voltage received from the dimmer switch is a reverse phase-control waveform. When the phase-control voltage received from the dimmer switch is a forward phase-control waveform, the load control device is operable to decrease the magnitude of the controllable-load current so as to conduct only enough current as is required in order to exceed rated latching and holding currents of the thyristor.

First claim

What is claimed is:

1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device adapted to be coupled to the AC power source through a dimmer switch, the load control device comprising:
a load control circuit adapted to be coupled to the electrical load for controlling the amount of power delivered to the electrical load;
a controller coupled to the load control circuit for controlling the amount of power delivered to the electrical load in response to a conduction period of a phase-control voltage received from the dimmer switch; and
a controllable-load circuit coupled to the controller, the controllable-load circuit configured to conduct a controllable-load current from the AC power source through the dimmer switch, the controllable-load circuit configured to maintain the magnitude of the controllable-load circuit constant for at least a portion of each half-cycle of the AC power source;
wherein the controller is configured to monitor the conduction period of the phase-control voltage and to cause the controllable-load circuit to decrease the magnitude of the controllable-load current from an initial magnitude in a first half-cycle to a decreased magnitude in a second subsequent half-cycle, such that the conduction period of the phase-control voltage when the controllable-load current has the decreased magnitude in the second half-cycle is the same as when the controllable-load current has the initial magnitude in the first half-cycle.

2. The load control device of claim 1 , wherein the decreased magnitude is less than the initial magnitude and greater than approximately zero amps.

3. The load control device of claim 2 , wherein the controller is configured to monitor the conduction period of the phase-control voltage after the magnitude of the controllable-load current has been decreased to the decreased magnitude in the second half-cycle and to further decrease the magnitude of the controllable-load current by an increment in a third half-cycle if the conduction period of the phase-control voltage has not changed.

4. The load control device of claim 3 , wherein the controller is configured to increase the magnitude of the controllable-load current by the increment in a fourth half-cycle if the conduction period of the phase-control voltage has changed.

5. The load control device of claim 1 , wherein the decreased magnitude is approximately zero amps.

6. The load control device of claim 5 , wherein the controller is configured to monitor the conduction period of the phase-control voltage after the magnitude of the controllable-load current has been decreased to approximately zero amps and to increase the magnitude of the controllable-load current in a subsequent half-cycle back to the initial magnitude if the conduction period of the phase-control voltage has changed.

7. The load control device of claim 1 , further comprising a communications circuit coupled to the controller.

8. The load control device of claim 7 , wherein the controller is further configured to determine a total number of load control devices coupled to the dimmer switch and receiving the phase-control voltage.

9. The load control device of claim 8 , wherein the controller is further configured to transmit a query message and to receive a query response message via the communications circuit to determine the total number of load control devices coupled to the dimmer switch.

10. The load control device of claim 9 , wherein the decreased magnitude of the controllable-load current is equal to a maximum magnitude divided by the total number of load control devices coupled to the dimmer switch.

11. The load control device of claim 7 , wherein the controller is configured to transmit a first digital message before decreasing the magnitude of the controllable-load current and to transmit a second digital message after decreasing the magnitude of the controllable-load current.

12. The load control device of claim 1 , wherein when the controller is configured to cause the controllable-load circuit to decrease the magnitude of the controllable-load current from the initial magnitude to the decreased magnitude, the controller further configured to control the load control circuit to deliver a constant amount of power to the electrical load.

13. A load control system for controlling the amount of power delivered from an AC power source to an electrical load, the load control system comprising:
a load control device adapted to be coupled to the electrical load for controlling the amount of power delivered to the electrical load; and
a dimmer switch comprising a thyristor coupled in series electrical connection between the AC power source and the load control device, the thyristor characterized by a rated holding current and configured to conduct a load current from the AC power source to the load control device, the dimmer switch configured to generate a phase-control voltage that is provided to the load control device to enable the load control device to adjust the amount of power being delivered to the electrical load in response to a conduction period of the phase-control voltage;
wherein the load control device is configured to conduct a controllable-load current from the AC power source through the thyristor of the dimmer switch, the load control device configured to maintain the magnitude of the controllable-load current constant for at least a portion of each half-cycle of the AC power source, the load control device configured to decrease the magnitude of the controllable-load current from an initial magnitude in a first half-cycle to a decreased magnitude in a second subsequent half-cycle, such that the decreased magnitude of the load current conducted through the thyristor in the second half-cycle exceeds the rated holding current.

14. A load control system for controlling the amount of power delivered from an AC power source to first and second electrical loads, the load control system comprising:
a first load control device adapted to be coupled to the first electrical load for controlling the amount of power delivered to the first electrical load;
a second load control device adapted to be coupled to the second electrical load for controlling the amount of power delivered to the second electrical load; and
a dimmer switch comprising a thyristor coupled in series electrical connection between the AC power source and the first and second load control devices, the thyristor characterized by a rated holding current and configured to conduct a load current from the AC power source to the first and second load control devices, the dimmer switch configured to generate a phase-control voltage that is provided to the first and second load control device to enable the first and second load control devices to adjust the amount of power being delivered to the respective electrical loads in response to a conduction period of the phase-control voltage;
wherein the load control devices are configured to conduct respective controllable-load currents from the AC power source through the thyristor of the dimmer switch, the load control devices configured to maintain the magnitude of each controllable-load current constant for at least a portion of each half-cycle of the AC power source, the load control devices each configured to adjust the magnitude of the respective controllable-load current from an initial magnitude in a first half-cycle to a decreased magnitude in a second subsequent half-cycle, such that a total magnitude of the respective controllable-load currents exceeds the rated holding current when th

Assignees

• Salvestrini Christopher James
• Bedell Ryan S
• Harte Matthew V
• Lutron Electronics Co

Inventors

• Salvestrini Christopher James
• Bedell Ryan S
• Harte Matthew V

Classifications

• H05B45/44

  with an active control inside an LED matrix · CPC title

• H05B45/14 Primary

  using electrical feedback from LEDs or from LED modules · CPC title

• H02M5/2576

  with digital control · CPC title

• H05B47/175

  by remote control · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title