Digitally controlled current regulator for high power solid state lighting

• US 20070267978A1
• Filed: 05/18/2007
• Published: 11/22/2007
• Est. Priority Date: 05/22/2006
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Exclara, Inc. (Million Star Technology Ltd.)
• Inventors: Rodriguez, Harry, Shteynberg, Anatoly
• Granted Patent: US 8,067,896 B2
• Time in Patent Office: Days
• US Class Current: 315/247
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• 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 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
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An exemplary apparatus embodiment provides for controlling current supplied to solid state lighting, such as light emitting diodes. An exemplary apparatus comprises a memory adapted to store a plurality of current parameters; and a control circuit adapted to modulate an energizing cycle time period for providing a substantially constant DC average current to the solid state lighting in response to a selected current parameter of the plurality of current parameters. In an exemplary embodiment, the control circuit modulates a current provided to the solid state lighting in response to a predetermined minimum current level (I_MIN) parameter and a predetermined peak current level (I_P) parameter, such that the DC average current level (I_O) is substantially proportional to one-half of a sum of a predetermined peak current level (“I_P”) and a predetermined minimum current level

$I_M\left(I_O\propto \frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

Claims

1. A current regulator for controlling current to solid state lighting, the current regulator couplable to a power source, the current regulator comprising:

a memory adapted to store a plurality of current parameters; and

a control circuit coupled to the memory, the control circuit adapted to modulate an energizing cycle time period for providing a substantially constant DC average current to the solid state lighting in response to a selected current parameter of the plurality of current parameters.

2. The current regulator of claim 1, wherein the plurality of current parameters comprise a predetermined minimum current level (I_MIN) and a predetermined peak current level (I_P).

3. The current regulator of claim 2, wherein the predetermined minimum current level (I_MIN) is substantially close to zero.

4. The current regulator of claim 2, wherein the control circuit is further adapted to provide the substantially constant DC average current by maintaining substantially constant a predetermined peak current level (I_P) and a predetermined minimum current level I_MIN.

5. The current regulator of claim 2, wherein the control circuit is further adapted to modulate the energizing cycle time period by providing an increasing current level to an inductor until the predetermined peak current level (I_P) is substantially reached and subsequently by providing a decreasing current level to the inductor until the predetermined minimum current level (I_MIN) is substantially reached.

6. The current regulator of claim 5, wherein the DC average current level (I_O) is substantially equal to one-half of a sum of a predetermined peak current level (“

I_P”

) and a predetermined minimum current level

$I_{\mathrm{MIN}}<br><br>\left(I_O\approx <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

7. The current regulator of claim 5, wherein the DC average current level (I_O) is substantially proportional to one-half of a sum of a predetermined peak current level (“

I_P”

) and a predetermined minimum current level

$I_M<br><br>\left(I_O\propto <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

8. The current regulator of claim 1, further comprising:

an inductor coupled to the solid state lighting;

a switch coupled to the control circuit and to the inductor or to the solid state lighting;

a current sensor coupled to the switch; and

a first comparator coupled to the current sensor and the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has increased to a predetermined peak level.

9. The current regulator of claim 8, further comprising:

a voltage sensor; and

a second comparator coupled to the voltage sensor and to the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle when the second comparator indicates that an inductor current has decreased to a predetermined minimum level.

10. The current regulator of claim 8, further comprising:

a second current sensor; and

a third comparator coupled to the current sensor and the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle when the third comparator indicates that an inductor current has decreased to a predetermined minimum level.

11. The current regulator of claim 1, wherein the power source is a battery, a DC power source, or is an AC power source coupled to a rectifier.

12. A method of providing power to a solid state lighting system, the method comprising:

starting an energizing cycle by providing current through an inductor coupled to the solid state lighting system;

monitoring the inductor current level;

reducing the inductor current level when a predetermined peak inductor current level is reached; and

commencing a next energizing cycle by increasing the inductor current level when a predetermined minimum inductor current level is reached.

13. The method of claim 12, wherein the predetermined minimum current level (I_MIN) is substantially close to zero.

14. The method of claim 12, further comprising:

providing a substantially constant DC average current by maintaining substantially constant a predetermined peak current level (I_P) and a predetermined minimum current level I_MIN.

15. The method of claim 14, wherein the DC average current level (I_O) is substantially equal to one-half of a sum of the predetermined peak current level (“

I_P”

) and the predetermined minimum current level

$I_{\mathrm{MIN}}<br><br>\left(I_O\approx <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

16. The method of claim 14, wherein the DC average current level (I_O) is substantially proportional to one-half of a sum of a predetermined peak current level (“

I_P”

) and a predetermined minimum current level

$I_M<br><br>\left(I_O\propto <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

17. The method of claim 12, further comprising:

determining the inductor current by measuring a first corresponding voltage; and

comparing the first corresponding voltage to a first predetermined reference voltage to determine when the predetermined peak inductor current level is reached.

18. The method of claim 12, further comprising:

determining the inductor current by measuring a second corresponding voltage; and

comparing the second corresponding voltage to a second predetermined reference voltage to determine when the predetermined minimum inductor current level is reached.

19. An apparatus for controlling current to solid state lighting, the apparatus couplable to a power source, the apparatus comprising:

a memory adapted to store a predetermined minimum current level (I_MIN) parameter and a predetermined peak current level (I_P) parameter; and

a controller coupled to the memory, the control circuit adapted to provide a substantially constant DC average current to the solid state lighting by modulating a current provided to the solid state lighting in response to the predetermined minimum current level (I_MIN) parameter and the predetermined peak current level (I_P) parameter.

20. The apparatus of claim 19, wherein the predetermined minimum current level (I_MIN) is substantially close to zero.

21. The apparatus of claim 19, wherein the controller is further adapted to provide the substantially constant DC average current by maintaining substantially constant a predetermined peak current level (I_P) and a predetermined minimum current level I_MIN.

22. The apparatus of claim 19 wherein the controller is further adapted to provide an increasing current level to an inductor until a predetermined peak current level (I_P) is substantially reached and to provide a decreasing current level to the inductor until a predetermined minimum current level (I_MIN) is substantially reached.

23. The apparatus of claim 19, wherein the DC average current level (I_O) is substantially equal to one-half of a sum of a predetermined peak current level (“

I_P”

) and a predetermined minimum current level

$I_{\mathrm{MIN}}<br><br>\left(I_O\approx <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

24. The apparatus of claim 19, wherein the DC average current level (I_O) is substantially proportional to one-half of a sum of the predetermined peak current level (“

I_P”

) and the predetermined minimum current level

$I_M<br><br>\left(I_O\propto <br><br>\frac{I_P+I_{\mathrm{MIN}}}{2}\right).$

25. The apparatus of claim 19, further comprising:

an inductor coupled to the solid state lighting;

and wherein the controller further comprises;

a control circuit;

a switch coupled to the control circuit and to the inductor or to the solid state lighting;

a current sensor coupled to the switch; and

a first comparator coupled to the current sensor and the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle and to turn the switch off when the first comparator indicates that an inductor current has reached a predetermined peak current level.

26. The apparatus of claim 25, wherein the controller further comprises:

a voltage sensor; and

a second comparator coupled to the voltage sensor and to the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle when the second comparator indicates that an inductor current has reached a predetermined minimum current level.

27. The apparatus of claim 25, wherein the controller further comprises:

a second current sensor; and

a third comparator coupled to the second current sensor and the control circuit;

wherein the control circuit is further adapted to turn the switch on to commence an energizing cycle when the third comparator indicates that an inductor current has reached a predetermined minimum current level.

28. A current regulator for providing substantially constant DC average current to solid state lighting, the current regulator couplable to a power source, the current regulator comprising:

an inductor coupled to the power source and coupled to the solid state lighting;

a switch coupled to the inductor or to the solid state lighting;

a first current sensor coupled to the switch;

a first comparator coupled to the first current sensor;

a voltage sensor coupled to the switch;

a second comparator coupled to the voltage sensor;

a second current sensor in series with the inductor;

a third comparator coupled to the second current sensor;

a memory adapted to store a plurality of current parameters; and

a control circuit coupled to the memory and to the first, second and third comparators, the control circuit adapted to turn the switch on to commence an energizing cycle when the second comparator or the third comparator indicate that an inductor current has reached a predetermined minimum level and to turn the switch off when the first comparator indicates that the inductor current has reached a predetermined peak level.