Illumination device control systems and methods
View Patent ↗In various embodiments, a control system for an electronic circuit iteratively applies voltage to and senses current from a load to regulate operation of the load.
1. A method for controlling, via application of first and second voltages, a circuit incorporating a load having a non-linear current-voltage relationship, the method comprising:
(A) applying the first voltage to the load;
(B) measuring a first current resulting from the first voltage applied to the load;
(C) applying the second voltage to the load;
(D) measuring a second current resulting from the second voltage applied to the load, a current difference between the second current and the first current having a magnitude;
(E) altering the second voltage by a voltage increment having a magnitude and polarity based at least in part on the magnitude of the current difference between the second current and the first current; and
(F) repeating steps (A)-(E) during operation of the circuit to regulate operation of the load notwithstanding any changes in the non-linear current-voltage relationship of the load during operation.
2. The method of claim 1 , further comprising setting the first current equal to the second current after step (D).
3. The method of claim 1 , wherein the second voltage is increased above a maximum operating voltage, further comprising decreasing the second voltage to the maximum operating voltage or less prior to applying the second voltage to the load.
4. The method of claim 1 , wherein the voltage increment decreases as a number of times steps (A)-(E) are repeated increases.
5. The method of claim 1 , wherein the magnitude and polarity of the voltage increment are determined from a table of pre-determined rules.
6. The method of claim 1 , wherein the non-linear current-voltage characteristic of the load comprises at least one of a global minimum or a global maximum therewithin.
7. The method of claim 1 , wherein the load comprises a lighting system, an intensity of light emitted by the lighting system being at least partially determined by a current at which the lighting system operates.
8. The method of claim 1 , wherein the non-linear current-voltage characteristic of the load comprises at least one of a local minimum or a local maximum therewithin.
9. The method of claim 1 , wherein step (E) comprises:
(i) if the magnitude of the current difference is greater than a pre-determined value, increasing the second voltage by the voltage increment; and
(ii) if the magnitude of the current difference is smaller than the pre-determined value, decreasing the second voltage by the voltage increment.
10. The method of claim 1 , further comprising (i) receiving an output voltage from a primary power source, and (ii) boosting the output voltage to a boosted voltage larger than the output voltage.
11. The method of claim 10 , wherein the output voltage is boosted by a boost circuit discrete from and spaced apart from the primary power source.
12. The method of claim 1 , wherein the voltage increment decreases during step (F) in the absence of temporary or permanent variations of the non-linear current-voltage relationship.
13. The method of claim 1 , further comprising pausing for a pre-determined amount of time prior to applying the second voltage to the load.
14. The method of claim 13 , wherein the pre-determined amount of time increases as a number of times steps (A)-(E) are repeated increases.
15. The method of claim 1 , wherein the circuit is configured to operate at a design point, the design point comprising a design current and a design voltage.
16. The method of claim 15 , wherein the voltage increment is less than about 10% of the design voltage.
17. The method of claim 1 , wherein the magnitude and polarity of the voltage increment are determined from a comparison of a pre-determined value to the magnitude of the current difference between the second current and the first current.
18. The method of claim 17 , wherein the pre-determined value is constant as steps (A)-(E) repeat.
19. The method of claim 17 , wherein (i) the circuit is configured to operate at a design point, the design point comprising a design current and a design voltage, and (ii) the pre-determined value is less than approximately 20% of the design current.
20. The method of claim 17 , wherein the pre-determined value decreases as a number of times steps (A)-(E) are repeated increases.
21. The method of claim 1 , wherein the load comprises a light-emitting array comprising:
first and second spaced-apart power conductors; and
a plurality of light-emitting strings, at least one light-emitting string (i) comprising a plurality of interconnected light-emitting diodes spaced along the light-emitting string, (ii) having a first end electrically coupled to the first power conductor, (iii) having a second end electrically coupled to the second power conductor, wherein the power conductors supply power to each of the light-emitting strings.
22. The method of claim 21 , wherein the light-emitting diodes emit substantially white light.
23. The method of claim 21 , wherein the light-emitting array comprises a plurality of control elements, at least one control element being (i) electrically connected to at least one light-emitting string and (ii) configured to utilize power supplied from the power conductors to control the current to the at least one light-emitting string to which it is electrically connected.
24. The method of claim 1 , wherein, after a plurality of repetitions of steps (A)-(E), the circuit operates at a stable operating range of voltages for at least a second plurality of repetitions of steps (A)-(E).
25. The method of claim 24 , further comprising decreasing the voltage increment at least once while the circuit operates at the stable operating range.
26. The method of claim 24 , further comprising pausing for a pre-determined amount of time prior to applying the second voltage to the load, the pre-determined amount of time increasing at least once while the circuit operates at the stable operating range.
27. The method of claim 26 , further comprising resetting the pre-determined amount of time to a default value if circuit operation diverges from the stable operating range.
28. The method of claim 1 , wherein the non-linear current-voltage characteristic of the load comprises a knee therewithin.
29. The method of claim 28 , wherein the current increases as the voltage increases in the knee region.
30. The method of claim 28 , wherein the current decreases as the voltage increases in the knee region.
31. The method of claim 1 , wherein (i) a first plurality of cycles of steps (A)-(E) repeating constitutes a start-up phase, and (ii) a second plurality of cycles of steps (A)-(E) repeating constitutes an operation phase, the start-up phase preceding the operation phase.
32. The method of claim 31 , wherein, during the start-up phase, the voltage increment decreases as a number of times steps (A)-(E) are repeated increases.
33. The method of claim 31 , wherein, during the operation phase, the voltage increment decreases as a number of times steps (A)-(E) are repeated increases.
34. The method of claim 31 , wherein, after the start-up phase, the circuit operates at a stable operating range of voltages for at least a portion of the operating phase.
35. A method for controlling, via application of first and second inputs, a system incorporating a load having a non-linear output-input relationship, the method comprising:
(A) applying the first input to the load;
(B) measuring a first output resulting from the first input applied to the load;
(C) applying the second input to the load;
(D) measuring a second output resulting from the second input applied to the load, an output difference between the second output and the first output having a magnitude;
(E) altering the second input by an input increment having a magnitude and polarity based at least in part on the magnitude of the output difference between the second output and the first output; and
(F) repeating steps (A)-(E) during operation of the system to regulate operation of the load notwithstanding any changes in the non-linear output-input relationship of the load during operation.
36. The method of claim 35 , further comprising setting the first output equal to the second output after step (D).
37. The method of claim 35 , wherein step (E) comprises:
(i) if the magnitude of the output difference is greater than a pre-determined value, increasing the second input by the input increment; and
(ii) if the magnitude of the output difference is smaller than the pre-determined, decreasing the second input by the input increment.
38. The method of claim 37 , wherein step (E) comprises, before altering the second input, setting the first output equal to the second output.