Method and Apparatus for Extending the Power Output Range of a Power Converter Used for a Lighting System

• US 20150022105A1
• Filed: 07/19/2013
• Published: 01/22/2015
• Est. Priority Date: 07/19/2013
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Supertex Incorporated (Microchip Technology Incorporated)
• Inventors: Walker, James T.
• Granted Patent: US 9,246,378 B2
• Time in Patent Office: Days
• US Class Current: 315/200.R
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/37 Converter circuits

Abstract

A method and system for extending the power output range of a power converter used for a lighting system is disclosed.

Claims

1. A power conversion system with a delayed start time, comprising:

a voltage detector coupled to a delay timer; and

a power converter controlled by an output of the delay timer, wherein the start time of the power converter is delayed.

2. The system of claim 1, further comprising:

a rectifier circuit for receiving an alternating current (AC) input and producing a direct current (DC) output;

wherein the voltage detector generates a signal when the DC output exceeds a threshold voltage.

3. The system of claim 2, wherein the delay timer is triggered by the signal.

4. The system of claim 3, wherein the power converter is enabled by the delay timer when a first time interval has elapsed after the delay timer is triggered.

5. The system of claim 4, wherein the delay timer comprises a capacitor and the first time interval is generated by a charging and discharging of the capacitor.

6. The system of claim 5, wherein the delay timer further comprises a switch that couples the capacitor to a current source in a first position and couples the capacitor to a current sink in a second position.

7. The system of claim 6, wherein the capacitor is charged during the time that the voltage detector output is off due to AC input not being present, and said capacitor is discharged during the time that said voltage detector output is on due to AC input being present.

8. The system of claim 7, wherein the capacitor charge and discharge currents have different values.

9. The system of claim 7, wherein the power converter is not operated until said capacitor discharges to a predetermined voltage.

10. The system of claim 4, further comprising:

a current sink circuit coupled to the rectifier circuit, wherein the current sink circuit draws current when the power converter is not enabled by the delay timer.

11. The system of claim 10, wherein the current sink circuit contains at least one MOSFET.

12. The system of claim 10,

wherein the amount of current drawn by the current sink circuit is proportional to a control voltage.

13. A dimmer for use with a lighting system, comprising:

a rectifier circuit for receiving an alternating current (AC) input and producing a direct current (DC) output;

a voltage detector for generating a signal when the DC output exceeds a threshold voltage;

a delay timer triggered by the signal; and

a power converter controlled by an output of the delay timer.

14. The system of claim 13, wherein the power converter is enabled by the delay timer when a first time interval has elapsed after the delay timer is triggered.

15. The system of claim 14, wherein the delay timer comprises a capacitor and the first time interval is generated by a charging and discharging of the capacitor.

16. The system of claim 15, wherein the delay timer further comprises a switch that couples the capacitor to a current source in a first position and couples the capacitor to a current sink in a second position.

17. The system of claim 16, wherein the capacitor is charged during the time that the voltage detector output is off due to AC input not being present, and said capacitor is discharged during the time that said voltage detector output is on due to AC input being present.

18. The system of claim 17, wherein the capacitor charge and discharge currents have different values.

19. The system of claim 17, wherein the power converter is not operated until said capacitor discharges to a predetermined voltage.

20. The system of claim 16, further comprising:

a current sink circuit coupled to the rectifier circuit, wherein the current sink circuit draws current when the power converter is not enabled by the delay timer.

21. The system of claim 20, wherein the current sink circuit contains at least one MOSFET.

22. The system of claim 20, wherein the amount of current drawn by the current sink circuit is proportional to a control voltage.

23. A method of dimming a lighting system, comprising:

receiving, by a rectifier circuit, an alternating current (AC) input and producing a direct current (DC) output;

generating, by a voltage detector, a signal indicating that the DC output exceeds a threshold voltage;

measuring, by a delay timer, a first time interval that is initiated by the signal;

controlling a power converter based on an output of the delay timer; and

,

providing, by the power converter, a voltage to a load.

24. The method of claim 23, wherein the load comprises a light emitting diode (LED) system.

25. The method of claim 23 further comprising a timer system for reducing the power converter operation time in proportion to the dimmer phase angle information.

26. The method of claim 23, wherein the load comprises at least one of the following:

an incandescent lamp, a compact fluorescent lamp (CFL), or an electrolumanescent panel.