CONFIGURABLE LOAD CONTROL DEVICE FOR LIGHT-EMITTING DIODE LIGHT SOURCES

• US 20110080111A1
• Filed: 06/11/2010
• Published: 04/07/2011
• Est. Priority Date: 10/07/2009
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Chitta, Venkatesh, Biery, Ethan Charles, Nuhfer, Matthew W., Shearer, Thomas M., Iyer, Kartik
• Granted Patent: US 8,492,988 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/18 using temperature feedback
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: H05B 45/397 Current mirror circuits
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: H05B 47/155 Coordinated control of two or more light sources
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A configurable light-emitting diode (LED) driver is adapted to control a plurality of different LED light sources, which may be rated to operate using different load control techniques, different dimming techniques, and different magnitudes of load current and voltage. The LED driver comprises a power converter circuit for generating a DC bus voltage, and an LED drive circuit for receiving the bus voltage and adjusting either the magnitude of the current conducted through the LED light source or the magnitude of the voltage across the LED light source. The LED driver is operable to dim the LED light source using either a pulse-width modulation technique or a constant current reduction technique, and may be configured using a programming device and a personal computer.

Claims

1. An LED driver for controlling an LED light source, the LED driver comprising:

a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage;

an LED drive circuit operable to receive the bus voltage and to control both the magnitude of a load current conducted through the LED light source and the magnitude of a load voltage produced across the LED light source; and

a control circuit coupled to the LED drive circuit for adjusting the magnitude of the load current conducted through the LED light source when operating in a current load control mode, and adjusting the magnitude of the load voltage produced across the LED light source when operating in a voltage load control mode.

2. The LED driver of claim 1, wherein the LED drive circuit comprises a controllable-impedance circuit coupled in series with the LED light source, the control circuit operatively coupled to the controllable-impedance circuit for controlling the controllable-impedance circuit to adjust the magnitude of the load current through the LED light source when operating in the current load control mode.

3. The LED driver of claim 2, wherein the controllable-impedance circuit comprises a linear regulator including a regulation transistor adapted to be coupled in series with the LED light source.

4. The LED driver of claim 3, wherein the control circuit is coupled to the power converter circuit for adjusting the magnitude of the bus voltage.

5. The LED driver of claim 4, wherein the power converter circuit comprises a flyback converter including a flyback transformer, a flyback switching transistor coupled in series with a primary winding of the flyback transformer, and a flyback controller for controlling the flyback switching transistor to be conductive and non-conductive to generate the bus voltage across a secondary winding of the flyback transformer, the flyback controller powered by a first low-voltage DC supply voltage.

6. The LED driver of claim 5, wherein the secondary winding of the flyback transformer comprises a center tap that produces a center tap voltage, the power converter comprising a first power supply operable to receive the center tap voltage and to generate a second low-voltage DC supply voltage at an output when the center tap voltage is above a cutover voltage.

7. The LED driver of claim 6, wherein the power converter further comprises a second power supply having an output coupled to the output of the first power supply, the second power supply operable to receive the bus voltage and to generate the second DC supply voltage when the center tap voltage is below approximately the cutover voltage.

8. The LED driver of claim 7, wherein the power converter further comprises a linear regulator operable to receive the second DC supply voltage and to generate a third low-voltage DC supply voltage for powering the control circuit.

9. The LED driver of claim 5, wherein the power converter comprises a flyback power supply coupled to a supply winding of the flyback transformer and operable to generate the first DC supply voltage.

10. The LED driver of claim 9, wherein the power converter comprises a startup power supply operable to receive the rectified voltage and to generate the first DC supply voltage before the flyback controller starts up.

11. The LED driver of claim 10, wherein the startup power supply comprises a cat-ear power supply.

12. The LED driver of claim 5, wherein the power converter comprises a buck-boost flyback converter.

13. The LED driver of claim 4, wherein the control circuit is operable to control the regulation transistor into the saturation region, and to adjust the magnitude of the bus voltage to thus control the magnitude of the load voltage produced across the LED light source when operating in the voltage load control mode.

14. The LED driver of claim 13, wherein the control circuit is operable to control the regulation transistor using a pulse-width modulation technique to adjust the intensity of the LED light source when operating in the voltage load control mode.

15. The LED driver of claim 13, wherein the control circuit is operable to measure the magnitude of the load voltage generated across the LED light source.

16. The LED driver of claim 13, wherein the control circuit is operable to measure the magnitude of the bus voltage and the magnitude of the voltage generated across the linear regulator, the control circuit further operable to calculate the magnitude of the load voltage generated across the LED light source by subtracting the magnitude of the voltage generated across the linear regulator from the magnitude of the bus voltage.

17. The LED driver of claim 4, wherein the control circuit is operable to control the regulation transistor to operate in the linear region to thus control the magnitude of the load current conducted through the LED light source when operating in the current load control mode.

18. The LED driver of claim 17, wherein the control circuit is operable to control the regulation transistor using a constant current reduction technique to adjust the intensity of the LED light source when operating in the current load control mode.

19. The LED driver of claim 17, wherein the control circuit is operable to control the regulation transistor using a pulse-width modulation technique to adjust the intensity of the LED light source when operating in the current load control mode.

20. The LED driver of claim 2, further comprising:

a communication circuit coupled to the control circuit, such that the control circuit is operable to receive a digital message including at least one parameter for the LED driver.

21. The LED driver of claim 20, wherein the parameter defines whether the control circuit should operate in the current load control mode or in the voltage load control mode.

22. The LED driver of claim 21, wherein the control circuit begins to operate in the current load control mode in response to the parameter, the parameter further defining a target current to which the control circuit will control the magnitude of the load current.

23. The LED driver of claim 21, wherein the control circuit begins to operate in the voltage load control mode in response to the parameter, the parameter further defining a target voltage to which the control circuit will control the magnitude of the load voltage.

24. The LED driver of claim 2, wherein the control circuit is coupled to the power converter circuit for adjusting the magnitude of the bus voltage to thus control the magnitude of the load voltage produced across the LED light source when operating in the voltage load control mode.

25. The LED driver of claim 24, wherein the control circuit is operable to control the LED drive circuit using a pulse-width modulation technique to adjust the intensity of the LED light source when operating in the voltage load control mode.

26. A power converter circuit for an LED driver for controlling an LED light source, the power converter circuit comprising:

a flyback transformer having primary and secondary windings, the primary winding operable to receive a rectified AC voltage;

a flyback switching transistor coupled in series with the primary winding of the flyback transformer;

a flyback controller for controlling the flyback switching transistor to be conductive and non-conductive to generate a bus voltage across a secondary winding of the flyback transformer and a center tap voltage at a center tap of the secondary winding, the flyback controller powered by a first low-voltage DC supply voltage;

a first power supply operable to receive the center tap voltage and to generate a second low-voltage DC supply voltage at an output when the center tap voltage is above a cutover voltage; and

a second power supply having an output coupled to the output of the first power supply, the second power supply operable to receive the bus voltage and to generate the second DC supply voltage when the center tap voltage is below approximately the cutover voltage.

27. The power converter circuit of claim 26, further comprising:

a linear regulator operable to receive the second DC supply voltage and to generate a third low-voltage DC supply voltage.

28. The power converter circuit of claim 27, further comprising:

a flyback power supply coupled to a supply winding of the flyback transformer and operable to generate the first DC supply voltage.

29. The power converter circuit of claim 28, further comprising:

a startup power supply operable to receive the rectified voltage and to generate the first DC supply voltage before the flyback controller starts up.

30. The power converter circuit of claim 29, wherein the startup power supply comprises a cat-ear power supply.

31. An LED driver for driving an LED light source including at least one LED, the LED driver comprising:

a first circuit receiving a rectified AC voltage and providing a DC bus voltage;

a second circuit receiving said DC bus voltage and producing one of a load current through said LED light source or a load voltage across said LED light source;

a control circuit having a first control input from said first circuit and a second control input from said second circuit and further having a first control output provided to said first circuit and a second control output provided to said second circuit;

said first control input comprising a signal related to said DC bus voltage;

said first control output comprising a control signal for controlling said first circuit to deliver a desired DC bus voltage;

said second control input comprising a signal related to either or both the load current provided by said second circuit through said LED light source and said load voltage provided by said second circuit to said LED light source;

said second control output comprising a control signal to regulate either or both said load current to said LED light source and said load voltage provided to said LED light source; and

wherein said second circuit comprises a linear regulator circuit having a power semiconductor device adapted to be coupled in series with said LED light source.

32. The LED driver of claim 31, wherein said second circuit is operable by said control circuit as either a voltage control mode driver or a current control mode driver.

33. The LED driver of claim 32, wherein said control circuit further comprises a dimming signal input and a dimming output, said dimming output controlling said power semiconductor device to dim said LED light source by reducing the average load current to said LED light source.

34. The LED driver of claim 33, wherein said dimming signal input comprises a phase control dimming signal provided by a phase control dimmer circuit.

35. The LED driver of claim 34, wherein said phase control dimmer circuit provides an AC voltage signal to a rectifier circuit, said rectifier circuit providing said rectified AC voltage having said phase control dimming signal, further comprising a phase-control input circuit receiving said rectified AC voltage and providing said dimming signal input as an output signal to said control circuit, said phase-control input circuit detecting said phase control dimming signal of said rectified AC voltage and converting said phase control dimming signal to a DC level dimming signal.

36. The LED driver of claim 33, wherein said dimming output comprises a dimming PWM signal, said dimming PWM signal controlling an on time of said power semiconductor device to control said average current to said LED light source.

37. The LED driver of claim 36, further comprising a second semiconductor device controlled by said dimming PWM signal, whereby said second semiconductor device turns off said power semiconductor device to turn off said load current to said LED light source for a predetermined time determined by a duty cycle of said dimming PWM signal thereby to dim said LED light source.

38. The LED driver of claim 33, wherein when said second circuit is operated in voltage control mode, said dimming output comprises a DC level signal to reduce said load current supplied to said LED light source.

39. The LED driver of claim 32, wherein when said second circuit is operated as a current control mode driver, said power semiconductor device is operated in a linear region by said control circuit providing said second control output to control said power semiconductor device into said linear region.

40. The LED driver of claim 39, wherein said first control output controls said first circuit to set said DC bus voltage to a predetermined voltage above said load voltage whereby said power semiconductor device can control said load current to said LED light source to a desired load current.

41. The LED driver of claim 39, wherein said second control output comprises a PWM signal, said second circuit further comprising a filter circuit receiving said second control output from said control circuit, said filter circuit providing a filtered signal to said power semiconductor device to control said power semiconductor device in said linear region to regulate said load current to said desired load current.

42. The LED driver of claim 32, wherein said first circuit comprises a switching mode power supply.

45. The LED driver of claim 31, further comprising a communication circuit coupled to said control circuit for communicating with a communication bus.

46. The LED driver of claim 31, further comprising a memory coupled to said control circuit for storing either or both said desired load voltage when said second circuit is operated in voltage control mode and said desired load current when said second circuit is operated in current control mode.

43. The LED driver of clam 42, wherein said first circuit comprises a flyback switching converter having a transformer providing DC isolation between said rectified AC signal and said second circuit.

44. The LED driver of claim 43, wherein said first control output comprises a PWM signal.

47. A system for configuring at least one output parameter of a lighting load power supply, the lighting load power supply having a programmable controller for regulating the output parameter to a target value and having a memory for storing a variable for setting the target value of the output parameter, the power supply having a communication port for receiving data for setting the target value, the system comprising:

a computer executing software allowing a user to select a target value of an output parameter of the lighting load power supply and having a first port providing data related to the selected output parameter; and

a programming device having a second port in communication with the first port of said computer and for providing data relating to said selected output parameter in a form usable by said lighting load power supply to said communication port of said lighting load power supply for programming said programmable controller to set the output parameter to the selected target value.

48. The system of claim 47, wherein the at least one output parameter comprises an output voltage of said lighting load power supply or an output current of said lighting load power supply.

49. The system of claim 48, wherein said lighting load power supply can be programmed to regulate in voltage mode control or current mode control, and wherein the software further allows the user to select either voltage mode control or current mode control and to configure said lighting load power supply for either voltage mode control or current mode control via said communication port.

50. The system of claim 49, wherein said lighting load power supply is dimmable, and wherein the software allows the user to select a dimming protocol for said lighting load power supply, the dimming protocols comprising pulse width modulation in voltage mode control and a selection of pulse width modulation or constant current reduction in current mode control.

51. The system of claim 50, wherein the at least one selected output parameter, the selection of voltage mode control or current mode control and the dimming protocol are stored in the memory of said lighting load power supply.

52. The system of claim 51, wherein, after storage in said memory, the selected target value stored may be locked in the memory to prevent alteration and wherein the lighting load power supply is labeled in accordance with the at least one selected output parameter.

53. The system of claim 50, wherein the software allows the user to select a control signal input type for dimming control of said lighting load power supply.

54. The system of claim 47, wherein the programming device comprises an interface for converting signals on said second port to a form usable by said lighting load power supply to program said selected output parameter to said target value.

55. The system of claim 54, wherein said interface comprises a first conversion device for converting signals on said second port to a first format and a second conversion device for converting signals in said first format to a second format configured for reception on said communication port of said lighting load power supply.

56. The system of claim 47, wherein the software automatically detects a model number of the lighting load power supply connected to the programming device.

57. The system of claim 56, wherein the software identifies a base model from the selected parameter and alerts the user if the base model is inconsistent with the connected lighting load power supply.

58. The system of claim 47, further wherein the software allows a user to select from a plurality of mechanically different form factors for said lighting load power supply.

59. The system of claim 47, wherein the lighting load power supply comprises an LED driver.

60. The system of claim 47, further wherein there are a plurality of base model lighting load power supplies and wherein the software identifies the base model from the at least one selected output parameter, the base models capable of operating in differing power ranges.

61. The system of claim 47, wherein the software is downloaded from the Internet from a server associated with a manufacturer of the lighting load power supply.

62. The system of claim 47, wherein the software allows a user to select the target value by directly selecting the target value or by selecting a model number of the lighting load power supply which has a target value associated with the selection of model number.

63. The system of claim 47, wherein the software determines a model number of the lighting load power supply as configured by the programming device from the at least one selected parameter.

64. A method of configuring at least one output parameter of a programmable lighting load power supply, the lighting load power supply having a programmable controller and a memory for storing the at least one output parameter, and further having a communication port for receiving data for configuring the lighting load power supply with the at least one output parameter, the method comprising:

providing software for use on a computer for selecting the at least one parameter;

allowing a user to select the at least one parameter using the software;

providing first data from the computer relating to the selection of the at least one parameter to a programming device; and

the programming device providing second data to the communication port of the lighting load power supply to program the programmable controller to set the output of the programmable lighting load power supply to the at least one output parameter.

65. The method of claim 64, wherein the at least one parameter comprises an output voltage or an output current of said lighting load power supply.

66. The method of claim 65, wherein the at least one parameter further comprises an output regulation method of said lighting load power supply, said output regulation method being either a load voltage control mode or a load current control mode.

67. The method of claim 66, wherein the at least one parameter further comprises a dimming method for said lighting load power supply, said dimming method comprising at least one of pulse width modulation or constant current reduction.

68. The method of claim 67, wherein the software allows a user to select a control signal input type for dimming control of said lighting load power supply.

69. The method of claim 66, wherein the software allows a user to select a physical form factor of the lighting load power supply.

70. The method of claim 64, further comprising:

identifying from the at least one selected output parameter a model number of the lighting load power supply;

displaying said model number on a display device of said computer; and

allowing the user to order the identified model number.

71. The method of claim 70, further comprising:

providing a limited number of base model number lighting load power supplies, and further wherein the software executes the steps of;

identifying a base model number lighting load power supply from the selected output parameter;

identifying a final model number of the lighting load power supply as further parameters of the lighting load power supply are selected by the user; and

allowing the user to order the final identified model number.

72. The method of claim 71, further comprising:

manufacturing the lighting load power supply in accordance with said identified final model number, said step of manufacturing including programming the base model number lighting load power supply with said selected output parameter.

73. The method of claim 72, further comprising:

locking the memory of said lighting load power supply so that the programmed output parameter cannot be changed.

74. The method of claim 73, further comprising:

labeling the power supply with the at least one output parameter.

75. The method of claim 64, further comprising:

changing the at least one parameter using the software; and

providing a sensor operable to provide feedback to said computer in response to the step of changing the at least one parameter.

76. The method of claim 75, wherein the sensor comprises at least one of a photosensor, a temperature sensor, or a power meter.

77. The method of claim 64, wherein the software automatically detects a model number of the lighting load power supply connected to the programming device.

78. The method of claim 77, wherein the software identifies a base model from the selected parameter and alerts the user if the base model is inconsistent with the connected lighting load power supply.

79. The method of claim 64, wherein the lighting load power supply comprises an LED driver.

80. The method of claim 64, further comprising the steps of:

selecting the at least one parameter using the software;

providing third data from the computer relating to the selection of the at least one parameter to a programming device, wherein the third data is different from the first data; and

the programming device providing fourth data to the communication port of the lighting load power supply to program the programmable controller to set the output of the programmable lighting load power supply to the at least one output parameter.