Ballasts with tapped inductor arrangements for igniting and powering high intensity discharge lamps

• US 6,194,845 B1
• Filed: 11/03/1999
• Issued: 02/27/2001
• Est. Priority Date: 11/03/1999
• Status: Expired due to Term

• Current Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Liu, Guang, Konopka, John G.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): VO, TUYET THI
• Application Number:
  US09/433,633
• Time in Patent Office: 482 Days
• Field of Search: 315/224, 315/291, 315/DIG.2, 315/DIG.5, 315/DIG.7, 315/209.R, 315/209.CD, 315/268, 315/276, 315/307
• US Class Current: 315/291
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H05B 41/2883 the controlled element being a DC/AC converter in the final stage, e.g. by harmonic mode starting
• CPC Class Codes: H05B 41/2888 the bridge being commutated at low frequency, e.g. 1kHz
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

A ballast (10) for powering a discharge lamp (70) comprises a source of direct current (100), an inverter (600), and an output circuit (700). Output circuit (700) provides high voltage starting pulses for igniting the lamp, and may be implemented with either a single-tapped inductor (720) or with dual tapped inductors (720,740). Preferably, inverter (600) may be realized as either a half-bridge inverter (600) or a full-bridge inverter (600′) that operates at a relatively low frequency so as to avoid acoustic resonance effects in the lamp. DC current source (100) provides a limited source of current and may be realized as either a dual current source (100) for powering a half-bridge inverter (600), or a single current source (100′) for powering a full-bridge inverter (600′).

Claims

1. A ballast for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter, comprising;

first and second input terminals for receiving the source of substantially direct current; and

an output terminal, wherein the inverter is operable to provide a periodically varying low frequency voltage between the output terminal and circuit ground during lamp starting and operation; and

an output circuit, comprising;

first and second output connections adapted for connection to the gas discharge lamp, wherein the second output connection is coupled to circuit ground;

a tapped inductor coupled between the inverter output terminal and the first output connection, the tapped inductor comprising;

a tap connection;

a first section coupled between the output terminal of the inverter and the tap connection; and

a second section coupled between the tap connection and the first output connection; and

a capacitor coupled between the tap connection and circuit ground.

2. The ballast of claim 1, wherein the second section of the tapped inductor has at least twice as many wire turns as the first section.

3. The ballast of claim 1, wherein the inverter is a half-bridge type inverter, comprising:

a first inverter switch coupled between the first input terminal and the output terminal;

a second inverter switch coupled between the output terminal and the second input terminal; and

an inverter control circuit coupled to the first and second inverter switches and operable to commutate the first and second inverter switches in a substantially complementary manner.

4. The ballast of claim 3, wherein the inverter control circuit commutates the first and second inverter switches at a frequency substantially less than 1000 hertz.

5. The ballast of claim 1, wherein the source of substantially direct current comprises:

a direct current (DC) voltage supply; and

a dual buck converter arrangement, comprising;

first and second input connections for receiving the DC voltage supply;

first and second output connections coupled to the first and second input terminals of the inverter;

a first switch coupled between the first input connection and a first node;

a first rectifier having a cathode coupled to the first node and an anode coupled to circuit ground; and

a first inductor coupled between the first node and the first output connection;

a first capacitor coupled between the first output connection and circuit ground;

a second switch coupled between the second input connection and a second node;

a second rectifier having an anode coupled to the second node and a cathode coupled to circuit ground; and

a second inductor coupled between the second node and the second output connection;

a second capacitor coupled between the second output connection and circuit ground; and

a buck control circuit coupled to, and operable to commutate, the first and second switches.

6. The ballast of claim 5, wherein the direct current voltage supply comprises:

a full-wave rectifier circuit having a pair of input terminals and a pair of output terminals, wherein the input terminals are adapted to receive a source of conventional alternating current;

a modified boost converter arrangement, comprising;

first and second input connections coupled to the output terminals of the full-wave rectifier circuit;

first and second output connections coupled to the first and second input connections of the dual buck converter arrangement;

a first inductor coupled between the first input connection and a first junction;

a second inductor coupled between the second input connection and a second junction;

a switch coupled between the first and second junctions;

a boost control circuit coupled to, and operable to commutate, the switch;

a first rectifier having an anode coupled to the first junction and a cathode coupled to the first output connection;

a second rectifier having a cathode coupled to the second junction and an anode coupled to the second output connection;

a first capacitor coupled between the first output connection and circuit ground, wherein circuit ground is coupled to one of the input terminals of the full-wave rectifier circuit; and

a second capacitor coupled between the second output connection and circuit ground.

7. A ballast for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter, comprising;

first and second input terminals for receiving the source of substantially direct current;

an output terminal; and

wherein the inverter is operable to provide a periodically varying low frequency voltage between the output terminal and circuit ground during lamp starting and operation; and

an output circuit, comprising;

first and second output connections adapted for connection to a discharge lamp;

a first inductor coupled between the inverter output terminal and the first output connection, the first inductor having a first tap connection;

a second inductor coupled between the second output connection and circuit ground, the second inductor having a second tap connection;

a capacitor coupled between the first and second tap connections.

8. The ballast of claim 7, wherein the source of substantially direct current comprises:

a direct current (DC) voltage supply; and

a dual buck converter arrangement, comprising;

first and second input connections for receiving the DC voltage supply;

first and second output connections coupled to the first and second input terminals of the inverter;

a first switch coupled between the first input connection and a first node;

a first rectifier having a cathode coupled to the first node and an anode coupled to circuit ground; and

a first inductor coupled between the first node and the first output connection;

a first capacitor coupled between the first output connection and circuit ground;

a second switch coupled between the second input connection and a second node;

a second rectifier having an anode coupled to the second node and a cathode coupled to circuit ground; and

a second inductor coupled between the second node and the second output connection;

a second capacitor coupled between the second output connection and circuit ground; and

a buck control circuit coupled to, and operable to commutate, the first and second switches.

9. The ballast of claim 8, wherein the direct current voltage supply comprises:

a full-wave rectifier circuit having a pair of input terminals and a pair of output terminals, wherein the input terminals are adapted to receive a source of conventional alternating current;

a modified boost converter arrangement, comprising;

first and second input connections coupled to the output terminals of the full-wave rectifier circuit;

first and second output connections coupled to the first and second input connections of the dual buck converter arrangement;

a first inductor coupled between the first input connection and a first junction;

a second inductor coupled between the second input connection and a second junction;

a switch coupled between the first and second junctions;

a boost control circuit coupled to, and operable to commutate, the boost switch;

a first rectifier having an anode coupled to the first junction and a cathode coupled to the first output connection;

a second rectifier having a cathode coupled to the second junction and an anode coupled to the second output connection;

a first capacitor coupled between the first output connection and circuit ground, wherein circuit ground is coupled to one of the input terminals of the full-wave rectifier circuit; and

a second capacitor coupled between the second output connection and circuit ground.

10. The ballast of claim 7, wherein the inverter is a half-bridge type inverter, comprising:

a first inverter switch coupled between the first input terminal and the output terminal;

a second inverter switch coupled between the output terminal and the second input terminal; and

an inverter control circuit coupled to the first and second inverter switches and operable to commutate the first and second inverter switches in a substantially complementary manner.

11. The ballast of claim 10, wherein the inverter control circuit commutates the first and second inverter switches at a frequency substantially less than 1000 hertz.

12. A ballast for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter, comprising;

first and second input terminals for receiving the source of substantially direct current;

first and second output terminals; and

wherein the inverter is operable to provide a periodically varying low frequency voltage between the first and second output terminals during lamp starting and operation;

an output circuit, comprising;

first and second output connections adapted for connection to the gas discharge lamp, wherein the second output connection is coupled to the second output terminal of the inverter;

a tapped inductor coupled between the first output terminal of the inverter and the first output connection, the tapped inductor comprising;

a tap connection;

a first section coupled between the first output terminal of the inverter and the tap connection; and

a second section coupled between the tap connection and the first output connection; and

a capacitor coupled between the tap connection and circuit ground.

13. The ballast of claim 12, wherein the second section of the tapped inductor has at least twice as many wire turns as the first section.

14. The ballast of claim 12, wherein the inverter is a full-bridge type inverter, comprising:

a first inverter switch coupled between the first input terminal and the first output terminal;

a second inverter switch coupled between the first output terminal and circuit ground;

a third inverter switch coupled between the first input terminal and the second output terminal;

a fourth inverter switch coupled between the second output terminal and circuit ground; and

a control circuit coupled to the first, second, third, and fourth inverter switches and operable to commutate the inverter switches in a substantially complementary manner, such that;

(i) when the first and fourth inverter switches are on, the second and third inverter switches are off; and

(ii) when the second and third inverter switches are on, the first and fourth inverter switches are off.

15. The ballast of claim 14, wherein the control circuit commutates the inverter switches at a frequency substantially less than 1000 hertz.

16. The ballast of claim 12, wherein the source of substantially direct current comprises:

a direct current (DC) voltage supply; and

a buck converter coupled between the DC voltage supply and the input terminals of the inverter.

17. The ballast of claim 16, wherein the direct current voltage supply comprises:

a full-wave rectifier circuit adapted to receive a source of alternating current and operable to provide a substantially unfiltered full-wave rectified output voltage; and

a boost converter coupled between the full-wave rectifier circuit and the buck converter.

18. A ballast for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter, comprising;

first and second input terminals for receiving the source of substantially direct current;

first and second output terminals; and

wherein the inverter is operable to provide a periodically varying low frequency voltage between the first and second output terminals during lamp starting and operation;

an output circuit, comprising;

first and second output connections adapted for connection to the gas discharge lamp, wherein the second output connection is coupled to the second output terminal of the inverter;

a tapped inductor coupled between the first output terminal of the inverter and the first output connection, the tapped inductor comprising;

a tap connection;

a first section coupled between the first output terminal of the inverter and the tap connection; and

a second section coupled between the tap connection and the first output connection; and

a capacitor coupled between the tap connection and the second output connection.

19. The ballast of claim 18, wherein the source of substantially direct current comprises:

a direct current (DC) voltage supply; and

a buck converter coupled between the DC voltage supply and the input terminals of the inverter.

20. The ballast of claim 19, wherein the DC voltage supply comprises:

a rectifier circuit adapted to receive a source of alternating current and to provide a substantially unfiltered full-wave rectified output voltage; and

a boost converter coupled between the rectifier circuit and the buck converter.

21. The ballast of claim 18, wherein the second section of the tapped inductor has at least twice as many wire turns as the first section.

22. The ballast of claim 21, wherein the inverter is a full-bridge type inverter, comprising:

a first inverter switch coupled between the first input terminal and the first output terminal;

a second inverter switch coupled between the first output terminal and circuit ground;

a third inverter switch coupled between the first input terminal and the second output terminal;

a fourth inverter switch coupled between the second output terminal and circuit ground; and

a control circuit coupled to the first, second, third, and fourth inverter switches and operable to commutate the inverter switches in a substantially complementary manner, such that;

(i) when the first and fourth inverter switches are on, the second and third inverter switches are off; and

(ii) when the second and third inverter switches are on, the first and fourth inverter switches are off.

23. The ballast of claim 22, wherein the control circuit commutates the inverter switches at a frequency substantially less than 1000 hertz.

24. A ballast for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter, comprising;

first and second input terminals for receiving the source of substantially direct current;

first and second output terminals; and

wherein the inverter is operable to provide a periodically varying low frequency voltage between the first and second output terminals during lamp starting and operation;

an output circuit, comprising;

first and second output connections adapted for connection to a discharge lamp;

a first inductor coupled between the first output terminal of the inverter and the first output connection, the first inductor having a first tap connection;

a second inductor coupled between the second inverter output terminal and the second output connection, the second inductor having a second tap connection;

a capacitor coupled between the first and second tap connections.

25. The ballast of claim 24, wherein the inverter is a full-bridge type inverter, comprising:

a first inverter switch coupled between the first input terminal and the first output terminal;

a second inverter switch coupled between the first output terminal and circuit ground;

a third inverter switch coupled between the first input terminal and the second output terminal;

a fourth inverter switch coupled between the second output terminal and circuit ground; and

a control circuit coupled to the first, second, third, and fourth inverter switches and operable to commutate the inverter switches in a substantially complementary manner, such that;

(i) when the first and fourth inverter switches are on, the second and third inverter switches are off; and

(ii) when the second and third inverter switches are on, the first and fourth inverter switches are off.

26. The ballast of claim 24, wherein the source of substantially direct current comprises:

a direct current (DC) voltage supply, comprising;

a rectifier circuit adapted to receive a source of alternating current and to provide a substantially unfiltered full-wave rectified output voltage; and

;

a boost converter coupled between the rectifier circuit and the buck converter; and

a buck converter coupled between the boost converter and the input terminals of the inverter.

27. A circuit for powering at least one gas discharge lamp, comprising:

a source of substantially direct current;

an inverter operable to accept the source of substantially direct current and to provide a periodically alternating low frequency output voltage during lamp startind and operation, the inverter including at least one inverter switch having an on-state and an off-state, and a control circuit for periodically commutating the inverter switch between the on-state and the off-state; and

an output circuit coupled to the inverter, adapted for connection to the gas discharge lamp, and operable to provide a transient high voltage for igniting the lamp and to deliver operating current to the lamp, wherein;

(i) initiation of the transient high voltage substantially coincides with commutation of the at least one inverter switch from the off-state to the on-state;

(ii) if the lamp fails to ignite, the transient high voltage is reapplied substantially coincident with commutation of the at least one inverter switch until at least such time as the lamp ignites, wherein the polarity of the transient high voltage is reversed on each application; and

(iii) the transient high voltage has a first frequency, the lamp operating current has a second frequency, and the first frequency is at least ten times greater than the second frequency.

28. The circuit of claim 27, wherein the inverter is a full-bridge type inverter, comprising:

first and second input terminals, wherein the second input terminal is coupled to circuit ground;

first and second output terminals;

a first inverter switch coupled between the first input terminal and the first output terminal;

a second inverter switch coupled between the first output terminal and circuit ground;

a third inverter switch coupled between the first input terminal and the second output terminal;

a fourth inverter switch coupled between the second output terminal and circuit ground; and

a control circuit coupled to the first, second, third, and fourth inverter switches and operable to commutate the inverter switches in a substantially complementary manner, such that;

(i) when the first and fourth inverter switches are on, the second and third inverter switches are off; and

(ii) when the second and third inverter switches are on, the first and fourth inverter switches are off.

29. The circuit of claim 28, wherein the output circuit comprises:

an inductor coupled between the first output terminal of the inverter and a first end of the gas discharge lamp, the inductor having a tap connection; and

a capacitor coupled between the tap connection and circuit ground, wherein the gas discharge lamp has a second end coupled to the second output terminal of the inverter.

30. The circuit of claim 28, wherein the output circuit comprises:

a first inductor coupled between the first output terminal of the inverter and a first end of the gas discharge lamp, the first inductor having a first tap connection;

a second inductor coupled between the second output terminal of the inverter and a second end of the gas discharge lamp, the second inductor having a second tap connection; and

a capacitor coupled between the first and second tap connections.