METHOD AND APPARATUS FOR CONTROLLING A LIGHTING DEVICE

• US 20140063857A1
• Filed: 08/23/2013
• Published: 03/06/2014
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: PENG, Hao, ZHANG, Wanfeng, CHOI, Jinho, DOAN, Tuyen
• Granted Patent: US 9,392,654 B2
• Time in Patent Office: Days
• US Class Current: 363/16
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Aspects of the disclosure provide a method. The method includes determining a power adjustment to a load, determining whether a switching frequency of a pulse width modulation (PWM) signal is within a specific range, and adjusting the switching frequency of the PWM signal based on the power adjustment to control power transfer to the load. The switching frequency is adjusted to remain in the specific range.

Claims

1. A method, comprising:

determining a power adjustment to a load;

determining whether a switching frequency of a pulse width modulation (PWM) signal is within a specific range; and

adjusting the switching frequency of the PWM signal based on the power adjustment to control power transfer to the load, the switching frequency being adjusted to remain in the specific range.

2. The method of claim 1, wherein determining the power adjustment in the load further comprises:

receiving a dimming characteristic of a power supply;

determining a reference power corresponding to the dimming characteristic;

estimating a transferred power that is controlled by the PWM signal; and

determining the power adjustment based on the reference power and the transferred power.

3. The method of claim 2, further comprising:

estimating a bleeding power that is consumed by a bleeder circuit; and

determining the power adjustment based on the reference power, the transferred power and the bleeding power.

4. The method of claim 1, further comprising:

generating the PWM signal with a pulse width being constant in each AC cycle; and

adjusting the pulse width of the PWM signal when the switching frequency is at a bound of the specific range.

5. The method of claim 1, further comprising:

generating the PWM signal with a pulse width being constant in each AC cycle; and

adjusting the pulse width of the PWM signal to shape a current profile in the AC cycle.

6. The method of claim 1, further comprising:

generating the PWM signal with a peak current being a first value in a primary winding of a magnetic component; and

adjusting a time window in an AC cycle to allow the peak current being a second value in the primary winding of the magnetic component when the switching frequency is at a bound of the specific range.

7. The method of claim 1, further comprising:

adjusting a timing window in an AC cycle to turn on a bleeder circuit that consumes power to bleed a portion of the transferred power when the switching frequency is at a bound of the specific range.

8. A circuit including a controller configured to:

determine a power adjustment to a load;

determine whether a switching frequency of a pulse width modulation (PWM) signal is in a specific range; and

adjust the switching frequency of the PWM signal based on the power adjustment to control power transfer to the load, the switching frequency being adjusted to remain in the specific range.

9. The circuit of claim 8, wherein the controller is configured to

receive a dimming characteristic of a power supply;

determine a reference power corresponding to the dimming characteristic;

estimate a transferred power that is controlled by the PWM signal; and

determine the power adjustment based on the reference power and the transferred power.

10. The circuit of claim 9, wherein the controller is configured to

estimate a bleeding power that is consumed by a bleeder circuit;

and

determine the power adjustment based on the reference power, the transferred power and the bleeding power.

11. The circuit of claim 8, wherein the controller is configured to:

generate the PWM signal with a pulse width being constant in each AC cycle; and

adjust the pulse width of the PWM signal when the switching frequency is at a bound of the specific range.

12. The circuit of claim 8, wherein the controller is configured to:

generate the PWM signal with a pulse width being constant in each AC cycle; and

adjust the pulse width of the PWM signal to shape a peak current profile in the AC cycle.

13. The circuit of claim 8, wherein the controller is configured to:

generate the PWM signal with a peak current being a first value in a primary winding of a magnetic component; and

adjust a time window in an AC cycle to allow the peak current being a second value in the primary winding of the magnetic component when the switching frequency is at a bound of the specific range.

14. The circuit of claim 8, wherein the controller is configured to:

adjust a timing window in an AC cycle to turn on a bleeder circuit that consumes power to bleed a portion of the transferred power when the switching frequency is at a bound of the specific range.

15. An apparatus, comprising:

a magnetic component configured to transfer power from a power supply source to a load;

a switch in connection with the magnetic component to control the power transfer; and

a controller configured to determine a power adjustment in the load, determine whether a switching frequency of a pulse width modulation (PWM) signal is in a specific range, and adjust the switching frequency of the PWM signal based on the power adjustment, the switching frequency being adjusted to remain in the specific range.

16. The apparatus of claim 15, wherein

a detecting circuit configured to detect a dimming characteristic of the power supply;

and

the controller is configured to

determine a reference power corresponding to the dimming characteristic;

estimate a transferred power that is controlled by the PWM signal; and

determine the power adjustment based on the reference power and the transferred power.

17. The apparatus of claim 16, wherein the controller is configured to

estimate a bleeding power that is consumed by a bleeder circuit;

and

determine the power adjustment based on the reference power, the transferred power and the bleeding power.

18. The apparatus of claim 15, wherein the controller is configured to:

generate the PWM signal with a pulse width being constant in each AC cycle; and

adjust the pulse width of the PWM signal when the switching frequency is at a bound of the specific range.

19. The apparatus of claim 15, wherein the controller is configured to:

generate the PWM signal with a peak current being a first value in a primary winding of the magnetic component; and

adjust a time window in an AC cycle to allow the peak current being a second value in the primary winding of the magnetic component when the switching frequency is at a bound of the specific range.

20. The apparatus of claim 15, wherein the controller is configured to:

adjust a timing window in an AC cycle to turn on a bleeder circuit that consumes power to bleed a portion of the transferred power when the switching frequency is at a bound of the specific range.