Lighting system electronic ballast or driver with shunt control for lighting control quiescent current

• US 8,653,759 B2
• Filed: 10/29/2010
• Issued: 02/18/2014
• Est. Priority Date: 10/29/2010
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Vigh, Peter, Krejcarek, Mate, Schmidt, Gabor, Gergely, Jacint
• Primary Examiner(s): Jackson, Jr., Jerome
• Assistant Examiner(s): Alaeddini, Borna
• Application Number:
  US12/915,759
• Publication Number:
  US 20120104975A1
• Time in Patent Office: 1,208 Days
• Field of Search: 315/225, 315/224, 315/276, 315/282, 315/291, 315/307, 315/362, 315/312, 315 46- 48, 315 74- 75, 315/119, 315/123, 315/125, 315/207, 315/306, 315/310, 363/80, 363/89, 363/97, 363/124, 363/126
• US Class Current: 315/310
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/37 Converter circuits

Abstract

Ballasts and LED drivers are presented for powering at least one light source, in which a shunt circuit provides a high impedance to allow operation of the light source when the AC input power exceeds a power threshold value, and provides a low impedance when the AC input power is below the power threshold value to prevent an output power stage from providing power to the light source.

Claims

1. A ballast or driver for powering at least one light source, comprising:

a ballast or driver input with first and second ballast or driver input terminals for receiving AC input power;

a rectifier circuit operatively coupled with the ballast or driver input to convert the AC input power to provide rectifier DC output power at first and second rectifier output terminals;

an output power stage comprising at least one power conversion circuit operatively coupled with the rectifier output terminals to convert the rectifier DC output power to provide ballast or driver output power to the at least one light source;

a DC bus capacitance coupled between the rectifier and the output power stage; and

a shunt circuit comprising first and second shunt circuit nodes coupled between the ballast or driver input and the DC bus capacitance, the shunt circuit being operative to provide a high impedance greater than or equal to an impedance threshold between the shunt circuit nodes when the AC input power is greater than or equal to a power threshold value, and to provide a low impedance below the impedance threshold between the shunt circuit nodes when the AC input power is below the power threshold value.

2. The ballast or driver of claim 1, where the low impedance of the shunt circuit limits a voltage of the DC bus capacitance to prevent the output power stage from providing ballast or driver output power to the at least one light source when the AC input power is below the power threshold value.

3. The ballast or driver of claim 2, where the shunt circuit nodes are coupled between the rectifier output terminals and the DC bus capacitance.

4. The ballast or driver of claim 2, where the shunt circuit nodes are coupled between the ballast or driver input and the rectifier.

6. The ballast or driver of claim 1, where the shunt circuit nodes are coupled between the rectifier output terminals and the DC bus capacitance.

7. The ballast or driver of claim 6, where the shunt circuit is an active circuit comprising:

a variable impedance circuit including at least one transistor with a first terminal coupled with the first shunt circuit node, a second terminal coupled with the second shunt circuit node, and a control terminal; and

a sensing circuit including a zener diode and a resistance coupled between the first shunt circuit node and the control terminal to selectively change the impedance of the at least one transistor based on a voltage across the first and second shunt circuit nodes.

8. The ballast or driver of claim 1, where the shunt circuit nodes are coupled between the ballast or driver input and the rectifier.

10. The ballast or driver of claim 1, where the shunt circuit is a positive temperature coefficient (PTC) resistance coupled between the first and second shunt circuit nodes.

11. The ballast or driver of claim 1, being an LED driver, where the output power stage comprises a DC to DC converter circuit operatively coupled with the rectifier output terminals to convert the rectifier DC output power to provide DC driver output power to at least one LED light source.

12. The ballast or driver of claim 1, being a fluorescent lamp ballast, where the output power stage comprises an inverter providing AC output power to at least one fluorescent light source.

13. The ballast or driver of claim 1, where the shunt circuit nodes are coupled between the rectifier output terminals and the DC bus capacitance, further comprising a diode coupled in series between the first shunt circuit node and the DC bus capacitance.

5. A ballast or driver for powering at least one light source, comprising:

a ballast or driver input with first and second ballast or driver input terminals for receiving AC input power;

a rectifier circuit operatively coupled with the ballast or driver input to convert the AC input power to provide rectifier DC output power at first and second rectifier output terminals;

an output power stage comprising at least one power conversion circuit operatively coupled with the rectifier output terminals to convert the rectifier DC output power to provide ballast or driver output power to the at least one light source;

a DC bus capacitance coupled between the rectifier and the output power stage; and

a shunt circuit comprising first and second shunt circuit nodes coupled between the ballast or driver input and the DC bus capacitance, the shunt circuit being operative to provide a high impedance greater than or equal to an impedance threshold between the shunt circuit nodes when the AC input power is greater than or equal to a power threshold value, and to provide a low impedance below the impedance threshold between the shunt circuit nodes when the AC input power is below the power threshold value;

where the power threshold value is less than a normal operating power range for powering the at least one light source and where the power threshold value is greater than an OFF-state quiescent power level of a light source control device coupled between an AC source and the ballast or driver.

14. The ballast or driver of claim 5, where the low impedance of the shunt circuit limits a voltage of the DC bus capacitance to prevent the output power stage from providing ballast or driver output power to the at least one light source when the AC input power is below the power threshold value.

15. The ballast or driver of claim 5, where the shunt circuit nodes are coupled between the rectifier output terminals and the DC bus capacitance.

16. The ballast or driver of claim 5, where the shunt circuit is an active circuit comprising:

a variable impedance circuit including at least one transistor with a first terminal coupled with the first shunt circuit node, a second terminal coupled with the second shunt circuit node, and a control terminal; and

a sensing circuit including a zener diode and a resistance coupled between the first shunt circuit node and the control terminal to selectively change the impedance of the at least one transistor based on a voltage across the first and second shunt circuit nodes.

17. The ballast or driver of claim 5, where the shunt circuit is a positive temperature coefficient (PTC) resistance coupled between the first and second shunt circuit nodes.

18. The ballast or driver of claim 5, where the shunt circuit nodes are coupled between the ballast or driver input and the rectifier.

9. A ballast or driver for powering at least one light source, comprising:

a ballast or driver input with first and second ballast or driver input terminals for receiving AC input power;

a rectifier circuit operatively coupled with the ballast or driver input to convert the AC input power to provide rectifier DC output power at first and second rectifier output terminals;

an output power stage comprising at least one power conversion circuit operatively coupled with the rectifier output terminals to convert the rectifier DC output power to provide ballast or driver output power to the at least one light source;

a DC bus capacitance coupled between the rectifier and the output power stage; and

a shunt circuit comprising first and second shunt circuit nodes coupled between the ballast or driver input and the DC bus capacitance, the shunt circuit being operative to provide a high impedance greater than or equal to an impedance threshold between the shunt circuit nodes when the AC input power is greater than or equal to a power threshold value, and to provide a low impedance below the impedance threshold between the shunt circuit nodes when the AC input power is below the power threshold value;

where the shunt circuit is an active circuit comprising;

a variable impedance circuit including at least one transistor with a first terminal coupled with the first shunt circuit node, a second terminal coupled with the second shunt circuit node, and a control terminal, and

a sensing circuit including a zener diode and a resistance coupled between the first shunt circuit node and the control terminal to selectively change the impedance of the at least one transistor based on a voltage across the first and second shunt circuit nodes.

19. The ballast or driver of claim 9, where the low impedance of the shunt circuit limits a voltage of the DC bus capacitance to prevent the output power stage from providing ballast or driver output power to the at least one light source when the AC input power is below the power threshold value.

20. The ballast or driver of claim 9, where the shunt circuit nodes are coupled between the rectifier output terminals and the DC bus capacitance.

21. The ballast or driver of claim 9, where the shunt circuit is a positive temperature coefficient (PTC) resistance coupled between the first and second shunt circuit nodes.

22. The ballast or driver of claim 9, where the shunt circuit nodes are coupled between the ballast or driver input and the rectifier.