LED POWER CONTROL METHODS AND APPARATUS

• US 20080012502A1
• Filed: 07/20/2007
• Published: 01/17/2008
• Est. Priority Date: 03/15/2004
• Status: Active Grant

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Color Kinetics Incorporated (Signify N.V.)
• Inventors: Lys, Ihor
• Granted Patent: US 7,737,643 B2
• Time in Patent Office: Days
• US Class Current: 315/247
• CPC Class Codes: H02M 1/0012 Control circuits using digital or numerical techniques in DC/DC converters H02M3/157, H02M3/33515; in DC-AC converters H02M7/53873
• CPC Class Codes: H02M 1/0019 the disturbance parameters being load current fluctuations
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 1/425 using a single converter stage both for correction of AC input power factor and generation of a high frequency AC output voltage
• CPC Class Codes: H02M 1/4291 by using a Buck converter to switch the input current
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/305 Frequency-control circuits
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Methods and apparatus for providing and controlling power to loads including one or more LEDs. In one example, a controlled predetermined power is provided to a load without requiring any feedback information from the load (i.e., without monitoring a load voltage and/or load current). In another example, a “feed-forward” power driver for an LED-based light source combines the functionality of a DC-DC converter and a light source controller, and is configured to control the intensity of light generated by the light source based on modulating the average power delivered to the light source in a given time period, without monitoring and/or regulating the voltage or current provided to the light source. In various examples, significantly streamlined circuits having fewer components, higher overall power efficiencies, and smaller space requirements are realized. Based on various power driver configurations, lighting apparatus incorporating one or more power drivers for one or more LED-based loads may be implemented, and multiple such lighting apparatus may be coupled together to form a lighting network in which operating power is efficiently provided throughout the network.

Claims

1. An apparatus, comprising:

at least one first white LED configured to generate first radiation having a first spectrum that includes perceivably white light; and

a first feed-forward driver coupled to the at least one first white LED and configured to controllably vary a first intensity of the first radiation without monitoring or regulating a first voltage or a first current provided to the at least one first white LED.

2. The apparatus of claim 1, wherein the first feed-forward driver comprises an energy transfer arrangement including:

at least one energy transfer element to store input energy derived from a power source and to provide output energy to the at least one first white LED;

at least one switch coupled to the at least one energy transfer element to control at least the input energy stored to the at least one energy transfer element; and

at least one diode,

wherein the energy transfer arrangement is configured as one of a buck converter, a boost converter, a buck-boost converter, a CUK converter, a flyback converter and a forward converter.

3. The apparatus of claim 2, wherein the energy transfer element includes one of a tapped inductor and a transformer having a non-unity turns ratio.

4. The apparatus of claim 2, further comprising at least one controller configured to receive at least one control signal that includes information representing the first intensity, the at least one controller further configured to output at least a first driver signal to control the at least one switch of the first feed-forward driver.

5. The apparatus of claim 4, wherein the at least one controller is configured to control at least one of a frequency and a duty cycle of the first driver signal so as to controllably vary the first intensity without using any feedback information relating to the at least one first white LED.

6. The apparatus of claim 5, wherein the at least one controller is configured to control at least one of the frequency and the duty cycle of the first driver signal based on a voltage output by the power source and the at least one control signal that includes the information representing the first and second intensities.

7. The apparatus of claim 5, wherein the at least one controller is configured to control the frequency of the first driver signal by controllably varying an effective frequency of the first driver signal using a pulse number modulation technique.

8. The apparatus of claim 7, wherein the at least one controller is configured to controllably vary the effective frequency of the first driver signal while holding substantially constant the duty cycle of the first driver signal.

9. The apparatus of claim 5, wherein the at least one controller is configured to controllably vary the duty cycle of the first driver signal while holding substantially constant the frequency of the first driver signal.

10. The apparatus of claim 5, wherein the at least one controller is configured to controllably vary both the frequency and the duty cycle of the first driver signal.

11. The apparatus of claim 5, wherein the at least one controller is configured to control at least one of the frequency and the duty cycle of the first driver signal based on a relative range of a desired intensity for the first intensity, as indicated by the information included in the at least one control signal received by the at least one controller.

12. The apparatus of claim 11, wherein the desired intensity includes at least a first range and a second range, wherein the at least one controller is configured to control only one of the frequency and the duty cycle of the first driver signal in the first range, and wherein the at least one controller is configured to control both of the frequency and the duty cycle of the first driver signal in the second range.

13. The apparatus of claim 11, wherein the desired intensity includes at least a first range, a second range, and a third range, and wherein the at least one controller is configured to control only the frequency of the first driver signal in the first range, only the duty cycle of the first driver signal in the second range, and both of the frequency and the duty cycle of the first driver signal in the third range.

14. The apparatus of claim 5, wherein the at least one controller is an addressable device so as to facilitate control of the apparatus via a network.

15. The apparatus of claim 1, further comprising:

at least one second LED configured to generate second radiation having a second spectrum different from the first spectrum; and

a second feed-forward driver coupled to the at least one second LED and configured to controllably vary a second intensity of the second radiation without monitoring or regulating a second voltage or a second current provided to the at least one second LED.

16. The apparatus of claim 15, wherein the first and second feed-forward drivers are configured to respectively controllably vary the first and second intensities based on at least one control signal that includes information representing the first and second intensities.

17. The apparatus of claim 16, wherein the at least one second LED includes at least one non-white LED.

18. The apparatus of claim 16, wherein the at least one second LED includes at least one second white LED.

19. The apparatus of claim 16, wherein the first and second feed-forward drivers are configured to independently controllably vary the first and second intensities based on the at least one control signal that includes the information representing the first and second intensities.

20. The apparatus of claim 19, further comprising at least one processor coupled to the first and second feed-forward drivers, the at least one processor configured to receive the at least one control signal that includes the information representing the first and second intensities, the at least one processor further configured to output at least a first driver signal to control the at least one switch of the first feed-forward driver and a second driver signal to control the at least one switch of the second feed-forward driver based on the information representing the first and second intensities.

21. The apparatus of claim 20, wherein the at least one processor is configured to control at least one of a frequency and a duty cycle of each driver signal so as to respectively control the first and second intensities, without using any feedback information relating to the at least one first white LED and the at least one second LED.

22. The apparatus of claim 21, wherein the at least one processor is an addressable device so as to facilitate control of the apparatus via a network.

23. The apparatus of claim 21, further comprising:

a full wave rectifier to receive an A.C. line voltage and output a rectified voltage; and

a power factor correction apparatus, coupled to the full wave rectifier and to the first and second feed-forward drivers, to receive the rectified voltage and output a DC voltage serving as the power source for the first and second feed-forward drivers.

24. The apparatus of claim 23, wherein the at least one processor is configured to control the power factor correction apparatus based at least in part on the at least one control signal that includes the information representing the first and second intensities.

25. The apparatus of claim 23, wherein the at least one processor is configured to control at least one of the frequency and the duty cycle of each driver signal based on the DC voltage output by the power factor correction apparatus and the at least one control signal that includes the information representing the first and second intensities.

26. A method, comprising acts of:

A) generating first radiation having a first spectrum that includes perceivably white light from at least one first white LED; and

B) controllably varying a first intensity of the first radiation without monitoring or regulating a first voltage or a first current provided to the at least one first white LED.

27. The method of claim 26, wherein the act B) comprises acts of:

storing input energy derived from a power source to at least one energy transfer element;

providing output energy from the at least one energy transfer element to the at least one first white LED; and

controlling at least the input energy stored to the at least one energy transfer element via at least one switch coupled to the at least one energy transfer element,

wherein the at least one energy transfer element and the at least one switch form part of an energy transfer arrangement that includes the at least one energy transfer element, the at least one switch, and at least one diode, and wherein the energy transfer arrangement is configured as one of a buck converter, a boost converter, a buck-boost converter, a CUK converter, a flyback converter and a forward converter.

28. The method of claim 27, wherein the energy transfer element includes one of a tapped inductor and a transformer having a non-unity turns ratio.

29. The method of claim 27, wherein the act B) comprises acts of:

receiving at least one control signal that includes information representing the first intensity;

generating at least a first driver signal to control the at least one switch; and

controlling at least one of a frequency and a duty cycle of the first driver signal so as to control the first intensity without using any feedback information relating to the at least one first white LED.

30. The method of claim 29, further comprising an act of:

receiving the at least one control signal that includes the information representing the first intensity as an addressed signal via a network.

31. The method of claim 26, further comprising acts of:

C) generating second radiation having a second spectrum, different from the first spectrum, from at least one second LED; and

D) controllably varying a second intensity of the second radiation without monitoring or regulating a second voltage or a second current provided to the at least one second LED.

32. The method of claim 31, further comprising an act of:

E) independently performing the acts B) and D) based on at least one control signal that includes information representing the first and second intensities.

33. The method of claim 32, wherein the at least one second LED includes at least one non-white LED.

34. The method of claim 32, wherein the at least one second LED include at least one second white LED.

35. The method of claim 32, wherein the act E) comprises an act of:

E1) generating at least a first driver signal to control the at least one first white LED and a second driver signal to control the at least one second LED, based on the at least one control signal that includes the information representing the first and second intensities.

36. The method of claim 35, wherein the act E1) comprises an act of:

E1a) controlling at least one of a frequency and a duty cycle of each driver signal so as to respectively control the first and second intensities, without using any feedback information relating to the at least one first white LED and the at least one second LED.

37. The method of claim 36, further comprising an act of:

receiving the at least one control signal that includes the information representing the first and second intensities as an addressed signal via a network.

38. The method of claim 36, further comprising acts of:

rectifying an A.C. line voltage to provide a rectified voltage;

controlling a current drawn from the rectified voltage to provide power factor correction; and

generating a DC voltage based on the rectified voltage, the DC voltage serving as the power source from which the input energy is derived.

39. The method of claim 38, wherein the act of controlling a current drawn from the rectified voltage comprises an act of controlling the current drawn from the rectified voltage based at least in part on the at least one control signal that includes the information representing the first and second intensities.