Power supply for a load control device

• US 7,423,413 B2
• Filed: 06/06/2006
• Issued: 09/09/2008
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Weightman, Russell, Dobbins, Aaron, Wu, Chen Ming, Steiner, James P, Perreault, David J
• Primary Examiner(s): Laxton; Gary L
• Application Number:
  US11/447,489
• Publication Number:
  US 20060273775A1
• Time in Patent Office: 826 Days
• Field of Search: 323/235, 323/237, 323/239, 323/241, 323/242, 323/243, 323/244, 323/246, 327/446, 327/452, 327/455, 327/456, 327/469, 327/476
• US Class Current: 323/242
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 5/257 using semiconductor devices only
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H05B 39/08 by shifting phase of trigger voltage applied to gas-filled controlling tubes also in controlled semiconductor devices in converters H02M5/00; with regulation G05F1/44

Abstract

A power supply for a load control device is disposed in series with an AC voltage source and a load and generates a substantially DC voltage for powering a controller of the load control device. The power supply is operable to provide substantially all voltage provided by the AC voltage source to the load and includes a controllably conductive device, a triggering device, and a charging circuit. The charging circuit is operable to charge an energy storage device and to conduct current to the load when the controllably conductive device is non-conductive. The controllably conductive device begins conducting the full load current when the energy storage device has charged to a predetermined amount of energy. Before the controllably conductive device begins to conduct, only a minimal voltage, which is substantially the same as the break-over voltage of the triggering circuit, develops across the power supply to allow the energy storage device to charge.

Claims

1. A power supply disposed in series with an AC load for charging an energy storage device from an AC voltage of an AC supply, the power supply comprising:

a controllably conductive device adapted to carry a load current from the AC supply to the load when the controllably conductive device is conductive;

a triggering circuit for causing the controllably conductive device to become conductive; and

a charging circuit for charging the energy storage device when the controllably conductive device is non-conductive, the charging circuit imposing a low voltage drop relative to the peak value of the AC voltage such that substantially all of the AC voltage is available to the load during the time when the controllably conductive device is non-conductive;

wherein the triggering circuit is operable to cause the controllably conductive device to become conductive when the energy storage device has charged to a predetermined amount of energy.

2. The power supply of claim 1, wherein the energy storage device comprises a storage capacitor.

3. The power supply of claim 2, wherein the charging circuit comprises a rectifier coupled across the controllably conductive device and supplies a DC voltage to the storage capacitor.

4. The power supply of claim 3, wherein the rectifier comprises a rectifier bridge.

5. The power supply of claim 1, wherein the controllably conductive device comprises a semiconductor switch.

6. The power supply of claim 5, wherein the semiconductor switch comprises a triac.

7. The power supply of claim 1, wherein the triggering circuit comprises a semiconductor triggering device.

8. The power supply of claim 7, wherein the semiconductor triggering device comprises a silicon bilateral switch, a diac, or a zener diode.

9. The power supply of claim 1, wherein the triggering circuit comprises a zener diode and two semiconductor switches.

10. A power supply adapted to be disposed in series electrical connection between an electrical load and an AC voltage source, the power supply operable to generate a DC voltage, the power supply comprising:

a controllably conductive device adapted to carry a load current from the AC voltage source to the electrical load when the controllably conductive device is conductive, the controllably conductive device having a control input;

a triggering circuit coupled to the control input of the controllably conductive device for causing the controllably conductive device to become conductive; and

a charging circuit operable to charge an energy storage capacitor when the controllably conductive device is non-conductive such that the DC voltage is produced across the energy storage capacitor, the charging circuit imposing a low voltage drop relative to the peak value of an AC voltage of the AC voltage source such that substantially all of the AC voltage is available to the load during the time when the controllably conductive device is non-conductive, the charging circuit operable to stop charging the energy storage capacitor when the controllably conductive device is conductive;

wherein the triggering circuit is operable to cause the controllably conductive device to become conductive in response to the DC voltage so as to cause the energy storage capacitor to stop charging.

11. A remote control device for an electrical load, the remote control device adapted to be coupled in series electrical connection between the electrical load and an AC voltage source, the remote control device comprising:

a communication circuit operable to transmit control information for controlling the electrical load;

a controller coupled to the communication circuit for providing the control information to the communication circuit; and

a power supply adapted to be coupled in series electrical connection between the electrical load and the AC voltage source and operable to generate a DC voltage to power the communication circuit and the controller, the power supply comprising a charging circuit for charging an energy storage device, the charging circuit imposing a low voltage drop relative to the peak value of an AC voltage of the AC voltage source such that substantially all of the AC voltage is available to the load during the time when the energy storage device is charging.

12. The remote control device of claim 11, wherein the power supply further comprises:

a first controllably conductive device adapted to carry a load current from the AC supply to the load when the first controllably conductive device is conductive, the first controllably conductive device having a control input; and

a triggering circuit coupled to the control input of the first controllably conductive device for causing the first controllably conductive device to become conductive; and

wherein the charging circuit is operable to charge the energy storage device when the first controllably conductive device is non-conductive, and the triggering circuit is operable to cause the first controllably conductive device to become conductive when the energy storage device has charged to a predetermined amount of energy.

13. The remote control device of claim 12, further comprising:

a second controllably conductive device having a control input coupled to the controller for causing the second controllably conductive device to become conductive; and

a resistor coupled in series electrical connection with the second controllably conductive device, the series combination of the second controllably conductive device and the resistor coupled in parallel electrical connection with the energy storage device;

wherein the controller is operable to render the second controllably conductive device conductive when the communication circuit is not transmitting the control information.

14. A method of generating a DC voltage in a remote control device adapted to be disposed in series electrical connection between an AC voltage source and an electrical load, the method comprising the steps of:

coupling a controllably conductive device is series electrical connection between the AC voltage source and the electrical load, the controllably conductive device having a control input;

charging an energy storage device through a charging circuit when the controllably conductive device is non-conductive, the charging circuit imposing a low voltage drop relative to the peak value of the AC voltage such that substantially all of the AC voltage is available to the load during the time when the controllably conductive device is non-conductive;

rendering the controllably conductive device conductive in response to the step of charging the energy storage device; and

stopping the charging of the energy storage device in response to the step of rendering the controllably conductive device conductive.

15. The method of claim 14, wherein the energy storage device comprises a capacitor.

16. The method of claim 14, wherein the step of rendering the controllably conductive device conductive comprises the step of causing the controllably conductive device to become conductive when the energy storage device has charged to a predetermined amount of energy.