Multiple location dimming system

• US 20070296347A1
• Filed: 06/22/2006
• Published: 12/27/2007
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Mosebrook, Donald, Carmen, Daniel F., Buck, Christopher
• Granted Patent: US 7,723,925 B2
• Time in Patent Office: Days
• US Class Current: 315/209.0SC
• CPC Class Codes: H05B 39/086 with possibility of remote control
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: H05B 47/17 Operational modes, e.g. switching from manual to automatic mode or prohibiting specific operations

Abstract

A multiple location dimming system comprises a plurality of dimmers coupled between an AC power source and a lighting load. Each of the plurality of dimmers is operable to control the intensity of the lighting load and comprises a controllably conductive device, e.g., a triac. The triacs of the plurality of dimmers are coupled in parallel electrical connection. Only an active one of the dimmers is operable to conduct a load current to the lighting load at any given time. A passive dimmer is operable to monitor the voltage across its triac in order to determine when the active dimmer is firing its triac. Accordingly, the passive dimmer is operable to fire its triac before the active dimmer fires its triac in order to “take over” control of the lighting load from the active dimmer to become the next active dimmer. Further, the passive dimmer is operable to determine the amount of power being delivered to the load and display this information on one or more status indicators.

Claims

1. A multiple location dimming system for controlling the power delivered to an electrical load from an AC power source, the system comprising:

a first dimmer coupled between the AC power source and the electrical load, the first dimmer comprising a first controllably conductive device for controlling the amount of power delivered to the electrical load; and

a second dimmer coupled between the AC power source and the electrical load, the second dimmer comprising a second controllably conductive device for controlling the amount of power delivered to the electrical load;

wherein the first dimmer is coupled to the second dimmer such that the first controllably conductive device is coupled in parallel electrical connection with the second controllably conductive device, the parallel combination of the first and second controllably conductive devices in series electrical connection between the AC power source and the electrical load.

2. The system of claim 1, wherein the first dimmer further comprises a first controller coupled to the first controllably conductive device for control of the first controllably conductive device and the second dimmer further comprises a second controller coupled to the second controllably conductive device for control of the second controllably conductive device.

3. The system of claim 2, wherein the first controller is operable to monitor a first electrical characteristic of the first dimmer and the second controller is operable to monitor a second electrical characteristic of the second dimmer.

4. The system of claim 3, wherein the first and second electrical characteristics comprises first and second dimmer voltages developed across the first and second controllably conductive devices, respectively.

5. The system of claim 4, wherein the first controller is operable to render the first controllably conductive device conductive at a first time each half-cycle of the AC power source and the second controller is operable to determine the first time in response to the second dimmer voltage.

6. The system of claim 5, wherein the second controller is operable to render the second controllably conductive device conductive at a second time before the first time during a first half-cycle.

7. The system of claim 6, wherein the first controller is operable to determine whether the second controller has rendered the second controllably conductive device conductive before the first time during the first half-cycle, and to render the first controllably conductive device non-conductive in response to the second controller rendering the second controllably conductive device conductive before the first time during the first half-cycle.

8. The system of claim 7, wherein the second controller is operable to render the second controllably conductive device conductive at the second time for a predetermined number of half-cycles after the first half-cycle.

9. The system of claim 6, wherein the second dimmer further comprises an actuator, the second controller operable to render the second controllably conductive device conductive at the second time in response to an actuation of the actuator.

10. The system of claim 5, wherein the second dimmer further comprises a status indicator coupled to the second controller, the second controller operable to control the status indicator in response to the first time.

11. The system of claim 3, wherein the first controller is operable to render the first controllably conductive device conductive for a first period of time each half-cycle of the AC power source and the second controller is operable to determine the first period of time of the first controllably conductive device in response to the second dimmer voltage.

12. The system of claim 11, wherein the second controller is operable to render the second controllably conductive device conductive for a second period of time greater than the first period of time.

13. The system of claim 12, wherein the first controller is operable to determine whether the second controller has rendered the second controllably conductive device conductive for the second period of time, and to render the first controllably conductive device non-conductive in response to the second controller rendering the second controllably conductive device conductive for the second period of time.

14. The system of claim 13, wherein the second controller is operable to render the second controllably conductive device conductive for the second period of time for a predetermined number of half-cycles.

15. The system of claim 3, wherein the first controller is operable to render the first controllably conductive device conductive at a first time each half-cycle of the AC power source and to determine whether the first dimmer voltage is a substantially low voltage at approximately the first time.

16. The system of claim 15, wherein the first controller is operable to determine whether the first dimmer voltage is a substantially low voltage before the first time, and to determine whether to render the first controllably conductive device conductive in response to the determination as to whether the first dimmer voltage is a substantially low voltage.

17. The system of claim 3, wherein the first electrical characteristic comprises a second load current conducted through the second controllably conductive device, and the second electrical characteristic comprises a first load current conducted through the first controllably conductive device.

18. The system of claim 17, wherein the first dimmer comprises a first current sense circuit operable to conduct the second load current and the second dimmer comprises a second current sense circuit operable to conduct the first load current.

19. The system of claim 17, wherein the first controller is operable to render the first controllably conductive device conductive at a first time each half-cycle of the AC power source and the second controller is operable to determine the first time in response to the second dimmer voltage.

20. The system of claim 1, wherein the first and second controllably conductive devices comprise bidirectional semiconductor switches.

21. The system of claim 20, wherein the bidirectional semiconductor switches comprise a triac.

22. The system of claim 20, wherein the bidirectional semiconductor switches comprise two field-effect transistors in anti-series connection.

23. The system of claim 1, further comprising:

a plurality of dimmers, each having a controllably conductive device, the controllably conductive devices of the plurality of dimmers coupled in parallel electrical connection.

24. A multiple location dimming system for controlling the power delivered to an electrical load from an AC power source, the system comprising:

a first dimmer coupled between the AC power source and the electrical load, the first dimmer comprising a first controllably conductive device operable to control the amount of power delivered to the electrical load by conducting load current from the AC power source to the electrical load at a first time each half-cycle of the AC power source; and

a second dimmer coupled between the AC power source and the electrical load, the second dimmer comprising a second controllably conductive device operable to control the amount of power delivered to the electrical load, the second dimmer coupled to the first dimmer such that the second controllably conductive device is coupled in parallel electrical connection with the first controllably conductive device, the parallel combination of the first and second controllably conductive devices in series electrical connection between the AC power source and the electrical load, only one of the first and the second controllably conductive devices operable to conduct the load current at a given time;

wherein the second dimmer is operable to render the second controllably conductive device conductive at a second time before the first time; and

wherein the first dimmer is operable to render the first controllably conductive device non-conductive in response to the second dimmer rendering the second controllably conductive device conductive at the second time.

25. A multiple location dimming system for controlling the power delivered to an electrical load from an AC power source, the system comprising:

a first dimmer coupled to the AC power source, the first dimmer comprising a first controllably conductive device for controlling the amount of power delivered to the electrical load; and

a second dimmer coupled to the electrical load, the second dimmer comprising a second controllably conductive device for controlling the amount of power delivered to the electrical load;

wherein the first and second dimmers each comprise at least one status indicator for displaying a status of the electrical load.

26. A load control device for controlling the amount of power delivered to an electrical load from an AC power source, the load control device comprising:

a first controllably conductive device coupled in series electrical connection between the AC power source and the electrical load for controlling the amount of power delivered to the load, the first controllably conductive device having a control input;

a sensing circuit operable to provide a control signal representative of a first electrical characteristic of the load control device; and

a first controller coupled to the control input of the first controllably conductive device and operable to receive the control signal from the sensing circuit;

wherein the load control device is operable to be coupled to a second load control device having a second controllably conductive device, the second controllably conductive device coupled in parallel electrical connection with the first controllably conductive device, the first controller operable to determine when the second controllably conductive device is changed between a non-conductive state and a conductive state in response to the control signal from the sensing circuit.

27. The load control device of claim 26, wherein the second controllably conductive device is rendered conductive at a first time each half cycle;

and

wherein the first controller is operable to render the first controllably conductive device conductive at a second time before the first time during a first half-cycle.

28. The load control device of claim 27, wherein the first controller is operable to render the first controllably conductive device conductive at the second time for a predetermined number of half-cycles after the first half-cycle.

29. The load control device of claim 28, wherein the first controller is operable to render the first controllably conductive device conductive at a third time each half-cycle after the predetermined number of half-cycles.

30. The load control device of claim 27, further comprising:

an actuator operatively coupled to the first controller;

wherein the first controller is operable to render the first controllably conductive device conductive at the second time in response to an actuation of the actuator.

31. The load control device of claim 26, wherein the second controllably conductive device is rendered conductive for a first period of time each half cycle;

and

wherein the first controller is operable to render the first controllably conductive device conductive for a second period of time greater than the first period of time during a first half-cycle.

32. The load control device of claim 31, wherein the first controller is operable to render the first controllably conductive device conductive for the second period of time for a predetermined number of half-cycles during the first half-cycle.

33. The load control device of claim 32, wherein the first controller is operable to render the first controllably conductive device conductive for a third period of time each half-cycle after the predetermined number of half-cycles.

34. The load control device of claim 26, wherein the first controller is operable to render the first controllably conductive device conductive at a first time each half-cycle and is operable to determine, immediately before rendering the first controllably conductive device conductive at the first time, whether the second controller has rendered the second controllably conductive device conductive.

35. The load control device of claim 34, wherein the first controller is operable to render the first controllably conductive device non-conductive in response to the second controller rendering the second controllably conductive device conductive before the first time during a first half-cycle.

36. The load control device of claim 35, wherein the first controller is operable to continue to render the first controllably conductive device non-conductive each half-cycle after the first half-cycle.

37. The load control device of claim 26, wherein the first controller is further operable to determine, in response to the control signal from the sensing circuit, the amount of power being delivered to the electrical load.

38. The load control device of claim 37, further comprising:

a status indicator operatively coupled to the first controller;

wherein the first controller controls the status indicator in response to the determination of the amount of power being delivered to the electrical load.

39. The load control device of claim 38, wherein the electrical load comprises a lighting load having an intensity dependent upon the amount of power delivered to the lighting load.

40. The load control device of claim 26, wherein the sensing circuit comprises a voltage monitoring circuit operable to provide a control signal representative of a voltage developed across the first controllably conductive device.

41. The load control device of claim 40, wherein the control signal is representative of a zero-crossing of the AC power source.

42. The load control device of claim 40, wherein the second controllably conductive device is rendered conductive at a first time each half cycle;

and

wherein the first controller is operable to render the first controllably conductive device conductive at a second time before the first time during a first half-cycle in response to the voltage across the first controllably conductive device.

43. The load control device of claim 26, wherein the sensing circuit comprises a current sense circuit operable to provide a control signal representative of a load current conducted through the second controllably conductive.

44. The load control device of claim 43, wherein the control signal is representative of a rising edge of the load current.

45. The load control device of claim 43, wherein the second controllably conductive device is rendered conductive at a first time each half cycle;

and

wherein the first controller is operable to render the first controllably conductive device conductive at a second time before the first time during a first half-cycle in response to the load current.

46. The load control device of claim 26, wherein the controllably conductive device comprises a bidirectional semiconductor switch.

47. The load control device of claim 46, wherein the bidirectional semiconductor switch comprises a triac.

48. The load control device of claim 46, wherein the bidirectional semiconductor switch comprises two field-effect transistors in anti-series connection.

49. A load control device for controlling the amount of power delivered to an electrical load from an AC power source, the load control device comprising:

a controllably conductive device coupled in series electrical connection between the AC power source and the electrical load for controlling the amount of power delivered to the load by conducting current to the electrical load for a first period of time each half-cycle of the AC power source, the controllably conductive device having a control input;

a voltage monitoring circuit coupled in parallel with the controllably conductive device and operable to provide a control signal representative of a voltage developed across the controllably conductive device; and

a controller coupled to the control input of the controllably conductive device and operable to receive the control signal from the voltage monitoring circuit, the controller operable to determine whether the voltage across the controllably conductive device is a substantially low voltage at approximately the beginning of the first period of time.

50. A first dimmer switch adapted to be coupled to a circuit including a power source, an electrical load, and a second dimmer switch, the first dimmer switch comprising:

a controllably conductive device operable to control the amount of power delivered from the power source to the electrical load;

a sensing circuit for generating a control signal representative of an electrical characteristic of the first dimmer switch; and

a controller operatively coupled to the controllably conductive device for controlling the amount of power delivered to the load, the controller operable to change the controllably conductive device between an active mode, in which the controllably conductive device is conducting the load current, and a passive mode, in which the controllably conductive device is not conducting the load current, in response to the control signal of the sensing circuit.

51. The dimmer switch of claim 50, wherein the electrical characteristic comprises a dimmer voltage across the controllably conductive device.

52. A method of controlling the amount of power delivered to an electrical load from an AC power source, the method comprising the steps of:

coupling a first controllably conductive device between the AC power source and the electrical load;

coupling a second controllably conductive device between the AC power source and the electrical load and in parallel electrical connection with the first controllably conductive device; and

controlling the first controllably conductive device to be conductive for at a first time each half-cycle of the AC power source.

53. The method of claim 52, further comprising the step of:

monitoring an electrical characteristic.

54. The method of claim 53, further comprising the step of:

determining the first time in response to the step of monitoring the electrical characteristic.

55. The method of claim 54, further comprising the step of:

rendering the second controllably conductive device conductive at a second time before the first time during a first half-cycle.

56. The method of claim 53, wherein the electrical characteristic comprises a second voltage across the second controllably conductive device.

57. The method of claim 56, further comprising the steps of:

monitoring a first voltage across the first controllably conductive device during the first half-cycle;

determining whether the second controllably conductive device is conductive during the first half-cycle; and

rendering the first controllably conductive device non-conductive during the first half-cycle in response to the step of determining that the second controllably conductive device is conductive.

58. The method of claim 57, further comprising the step of:

controlling the second controllably conductive device to be conductive at the second time for a predetermined number of half-cycles after the first half-cycle.

59. The method of claim 56, further comprising the step of:

receiving an input from a user interface prior to the step of rendering the second controllably conductive device conductive at the second time.

60. The method of claim 55, wherein the electrical characteristic comprises a load current through the first controllably conductive device.

61. The method of claim 54, further comprising the step of:

determining if the first voltage is a substantially low voltage at approximately the first time.

62. The method of claim 61, further comprising the steps of:

determining if the first voltage is a substantially low voltage immediately before the first time; and

determining whether to render the first controllably conductive device conductive in response to the step of determining if the first voltage is a substantially low voltage.

63. The method of claim 54, further comprising the step of:

controlling a status indicator in response to the step of determining the first time.

64. A method of controlling the amount of power delivered to an electrical load from an AC power source, the method comprising the steps of:

coupling a first controllably conductive device between the AC power source and the electrical load;

coupling a second controllably conductive device between the AC power source and the electrical load and in parallel electrical connection with the first controllably conductive device; and

controlling the first controllably conductive device to be conductive for a first period of time each half-cycle of the AC power source.

65. The method of claim 64, further comprising the step of:

monitoring a second voltage across the second controllably conductive device.

66. The method of claim 65, further comprising the step of:

determining whether the first controllably conductive device is rendered conductive each half-cycle for the first period of time in response to the step of monitoring the second voltage.

67. The method of claim 66, further comprising the step of:

rendering the second controllably conductive device conductive for a second period of time greater than the first period of time.

68. The method of claim 67, further comprising the steps of:

monitoring a first voltage across the first controllably conductive device;

determining whether the second controllably conductive device is conductive; and

rendering the first controllably conductive device non-conductive in response to the step of determining that the second controllably conductive device is conductive.

69. A method of controlling the amount of power delivered to an electrical load from an AC power source, the method comprising the steps of:

coupling a plurality of controllably conductive devices between the AC power source and the electrical load, the plurality of controllably conductive devices coupled in parallel electrical connection; and

selectively controlling one of the plurality of controllably conductive devices to be conductive for a period of time each half-cycle of the AC power source.

70. A multiple location dimming system for controlling the power delivered to an electrical load from an AC power source, the system comprising:

a plurality of dimmers wired in parallel electrical connection, each dimmer operating independently or with the other dimmers to control the amount of power delivered to the electrical load;

wherein the dimmers communicate with each other.

71. The system of claim 70, wherein the dimmers communicate with each other by adjusting a firing angle.

72. The system of claim 70, wherein the dimmers communicate to take control of the amount of power delivered to the electrical load.