Power conversion with controlled capacitance charging including attach state control

• US 9,184,661 B2
• Filed: 03/15/2013
• Issued: 11/10/2015
• Est. Priority Date: 08/27/2012
• Status: Expired due to Fees

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John L., King, Eric J.
• Primary Examiner(s): DONOVAN, LINCOLN D
• Assistant Examiner(s): Mattison, David
• Application Number:
  US13/836,423
• Publication Number:
  US 20140055055A1
• Time in Patent Office: 970 Days
• Field of Search: 315/228
• US Class Current: 1/1
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

An electronic system includes a controller that actively controls a rate of charging and discharging of an energy storage capacitor to maintain compatibility with a dimmer. The controller actively controls charging of a capacitor circuit in a switching power converter to a first voltage level across the capacitor circuit. The controller further allows the capacitor to discharge to obtain a second voltage level across the capacitor circuit. The second voltage level is sufficient to draw a current through a phase-cut dimmer to prevent the dimmer from prematurely resetting. The first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

Claims

1. A method comprising:

actively controlling a rate of charging of a capacitor circuit in a switching power converter to a first voltage level across the capacitor circuit, wherein actively controlling the rate of charging of the capacitor circuit comprises actively controlling conductivity of a switch coupled to the capacitor circuit, and the conductivity of the switch controls current flow in a sole current path for current charging the capacitor circuit; and

allowing the capacitor to discharge to obtain a second voltage level across the capacitor circuit, wherein the second voltage level is sufficient to draw a current through a phase-cut dimmer to prevent the dimmer from prematurely resetting, and the first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

2. The method of claim 1 wherein actively controlling charging of the capacitor comprises:

controlling current through the capacitor circuit at a rate that prevents a triac of the phase-cut dimmer from prematurely resetting and allows the voltage across the capacitor circuit to reach the first voltage level.

3. The method of claim 2 wherein controlling current through the capacitor circuit further comprises:

controlling conductivity of a switch coupled to the capacitor circuit.

4. The method of claim 3 wherein the switch is a member of a group consisting of:

a bipolar junction transistor and a field effect transistor.

5. The method of claim 1 wherein actively controlling charging of the capacitor circuit further comprises:

setting the first voltage level and the second voltage level so that discharging a capacitor network from the first voltage level to the second voltage level supplies an approximate amount of energy to a load, which is coupled to the switching power converter, wherein the amount of energy correlates with a phase angle of an input line voltage supplied to the switching power converter.

6. The method of claim 1 wherein:

actively controlling charging of the capacitor circuit further comprises;

controlling one or more switches to regulate current from a terminal of the capacitor circuit that is coupled to a reference voltage node; and

allowing the capacitor to discharge to obtain a second voltage level across the capacitor circuit comprises;

controlling the one or more switches to cease current flow through the one or more switches.

7. The method of claim 1 wherein the capacitor circuit consists of a single capacitor.

8. The method of claim 1 wherein the capacitor circuit comprises multiple capacitors.

9. The method of claim 1 wherein the first voltage level across the capacitor circuit is less than a peak value of an input line voltage supplied to the switching power converter.

10. The method of claim 1 wherein the phase-cut dimmer is a triac based dimmer that includes a triac, and the second voltage level is sufficient to draw a current through the triac-based dimmer to prevent the triac of the dimmer from prematurely resetting, and the first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

11. An apparatus comprising:

a controller, wherein the controller is configured to;

actively control a rate of charging of a capacitor circuit in a switching power converter to a first voltage level across the capacitor circuit, wherein to actively control the rate of charging of the capacitor circuit comprises to actively control conductivity of a switch coupled to the capacitor circuit, and the conductivity of the switch controls current flow in a sole current path for current charging the capacitor circuit; and

allow the capacitor to discharge to obtain a second voltage level across the capacitor circuit, wherein the second voltage level is sufficient to draw a current through a phase-cut dimmer to prevent the dimmer from prematurely resetting, and the first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

12. The apparatus of claim 11 wherein to actively control charging of the capacitor the controller is further configured to:

control current through the capacitor circuit at a rate that prevents a triac of the phase-cut dimmer from prematurely resetting and allows the voltage across the capacitor circuit to reach the first voltage level.

13. The apparatus of claim 12 wherein to control current through the capacitor circuit the controller is further configured to:

control conductivity of a switch coupled to the capacitor circuit.

14. The apparatus of claim 13 wherein the switch is a member of a group consisting of:

a bipolar junction transistor and a field effect transistor.

15. The apparatus of claim 11 wherein to actively control charging of the capacitor circuit the controller is further configured to:

set the first voltage level and the second voltage level so that discharging a capacitor network from the first voltage level to the second voltage level supplies an approximate amount of energy to a load, which is coupled to the switching power converter, wherein the amount of energy correlates with a phase angle of an input line voltage supplied to the switching power converter.

16. The apparatus of claim 11 wherein:

to actively control charging of the capacitor circuit the controller is further configured to;

control one or more switches to regulate current from a terminal of the capacitor circuit that is coupled to a reference voltage node; and

to allow the capacitor to discharge to obtain a second voltage level across the capacitor circuit the controller is further configured to;

control the one or more switches to cease current flow through the one or more switches.

17. The apparatus of claim 11 wherein the capacitor circuit consists of a single capacitor.

18. The apparatus of claim 11 wherein the capacitor circuit comprises multiple capacitors.

19. The apparatus of claim 11 wherein the first voltage level across the capacitor circuit is less than a peak value of an input line voltage supplied to the switching power converter.

20. The apparatus of claim 11 wherein the phase-cut dimmer is a triac based dimmer that includes a triac, and the second voltage level is sufficient to draw a current through the triac-based dimmer to prevent the triac of the dimmer from prematurely resetting, and the first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

21. The apparatus of claim 11 wherein the controller comprises an integrated circuit.

22. An apparatus comprising:

a switching power converter having a switch and conductivity of the switch controls power conversion by the switching power converter;

a load coupled to the switching power converter;

a capacitor circuit coupled to the switching power converter;

a switch coupled to the capacitor circuit; and

a controller, coupled to the switch of the switching power converter and to the capacitor circuit, wherein the controller is configured to;

actively control a rate of charging of a capacitor circuit in a switching power converter to a first voltage level across the capacitor circuit, wherein to actively control the rate of charging of the capacitor circuit comprises to actively control conductivity of the switch, and the conductivity of the switch controls current flow in a sole current path for current charging the capacitor circuit; and

allow the capacitor to discharge to obtain a second voltage level across the capacitor circuit, wherein the second voltage level is sufficient to draw a current through a phase-cut dimmer to prevent the dimmer from prematurely resetting, and the first voltage is sufficient to allow the capacitor to discharge to the second voltage level during each cycle of the line voltage.

23. The apparatus of claim 22 wherein the load comprises one or more light emitting diodes.