Systems and methods for a transformer configuration with a tree topology for current balancing in gas discharge lamps

• US 20050093482A1
• Filed: 10/20/2004
• Published: 05/05/2005
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Original Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Inventors: Ball, Newton E.
• Granted Patent: US 7,250,726 B2
• Time in Patent Office: Days
• US Class Current: 315/277
• CPC Class Codes: H05B 41/2827 using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations

Abstract

An apparatus and methods for balancing current in multiple negative impedance gas discharge lamp loads. Embodiments advantageously include balancing transformer configurations that are relatively cost-effective, reliable, efficient, and good performing. Embodiments include configurations that are applicable to any number of gas discharge tubes, such as cold cathode fluorescent lamps. The balancing transformer configuration techniques permit a relatively small number of power inverters, such as one power inverter, to power multiple lamps in parallel. One embodiment of a balancing transformer includes a safety winding which can be used to protect the balancing transformer in the event of a lamp failure and can be used to provide an indication of a failed lamp.

Claims

1. A method of paralleling lamps in a balanced manner, the method comprising:

providing a plurality of at least 4 lamps;

arranging at least 3 two-way balancing transformers in a hierarchical arrangement, wherein the hierarchical arrangement divides current in a balanced manner from a single current path to two current paths, and then from the two current paths to at least four current paths, wherein at least 1 of the at least 3 two-way balancing transformers incorporates a safety winding;

operatively coupling the at least four current paths to the at least 4 lamps to parallel the lamps; and

electrically coupling the safety winding to anti-parallel diodes.

2. The method as defined in claim 1, further comprising winding the balancing windings for the two-way balancing transformers in separate windings.

3. A lamp assembly comprising:

a plurality of at least 4 lamps;

means for arranging two-way balancing transformers in a straight tree, where the straight tree of two-way balancing transformer is operatively coupled to the plurality of at least 4 lamps to divide current evenly among the lamps; and

means for limiting voltage in the two-way balancing transformers with safety windings.

4. The lamp assembly as defined in claim 3, wherein the lamp assembly is substantially floating with respect to ground.

5. An assembly of negative-impedance gas-discharge lamp loads comprising:

a plurality of at least 4 lamp loads, where the lamp loads each have a first end and a second end;

a first terminal and a second terminal for receiving power from a secondary winding of an inverter transformer for driving the plurality of lamp loads in parallel; and

a split tree of two-way balancing transformers with at least 2 levels in the tree, where a first level is operatively coupled to first ends of the lamp loads and a second level is operatively coupled to the second ends of the lamp loads, where the first level is operatively coupled to the first terminal and the second level is operatively coupled to the second terminal.

6. The assembly as defined in claim 5, wherein the split tree further comprises at least one additional level between the first level or the second level and the first terminal or the second terminal.

7. The assembly as defined in claim 5, wherein none of the two-way balancing transformers is bifilar wound.

8. The assembly as defined in claim 5, wherein at least one of the two-way balancing transformers includes a safety winding electrically coupled to anti-parallel diodes.

9. The assembly as defined in claim 5, further comprising capacitors operatively coupled in series with the lamp loads.

10. The assembly as defined in claim 5, wherein the first terminal and the second terminal are substantially floating and not operatively coupled with respect to ground.

11. A method of paralleling negative-impedance gas-discharge lamp loads in a balanced manner, the method comprising:

providing a plurality of at least 4 lamp loads;

arranging at least 3 two-way balancing transformers in a split tree, wherein the split tree arrangement divides current in a balanced manner from at least a single current path to four current paths, wherein the split tree arrangement provides at least one two-way balancing transformer at both ends of the lamp loads; and

operatively coupling the at least four current paths to the at least 4 lamp loads to parallel the lamp loads.

12. The method as defined in claim 11, further comprising incorporating a safety winding in the two-way balancing transformers and electrically coupling the safety winding to anti-parallel diodes.

13. The method as defined in claim 11, further comprising winding the balancing windings for each of the two-way balancing transformers in separate sections of a bobbin.

14. An assembly of negative-impedance gas-discharge lamp loads comprising:

a plurality of at least 4 lamp loads; and

means for splitting two-way balancing transformers between both ends of the lamp loads to divide current evenly among the lamp loads in a hierarchical configuration.

15. The assembly as defined in claim 14, wherein the assembly is substantially floating with respect to ground.

16. An assembly of negative-impedance gas-discharge lamp loads comprising:

a plurality of at least 4 lamp loads, where the lamp loads each have a first end and a second end;

a first terminal and a second terminal for receiving power from an inverter transformer for driving the plurality of lamp loads in parallel; and

a partially split tree of two-way balancing transformers, wherein the partially split tree is coupled to the plurality of at least 4 lamp loads and to the first terminal and the second terminal, wherein at least a first two-way balancing transformer of the partially split tree is operatively coupled to first ends of corresponding lamp loads and at least a second two-way balancing transformer is operatively coupled to second ends of corresponding lamp loads, and where a third two-way balancing transformer is operatively coupled to the first two-way balancing transformer or the second two-way balancing transformer.

17. The assembly as defined in claim 16, wherein none of the two-way balancing transformers is bifilar wound.

18. The assembly as defined in claim 16, wherein at least one of the two-way balancing transformers includes a safety winding electrically coupled to anti-parallel diodes.

19. The assembly as defined in claim 16, further comprising capacitors operatively coupled in series with the lamp loads.

20. The assembly as defined in claim 16, wherein the first terminal and the second terminal are substantially floating and not operatively coupled with respect to ground.

21. A method of paralleling negative-impedance gas-discharge lamp loads in a balanced manner, the method comprising:

providing a plurality of at least 4 lamp loads with first ends and second ends;

arranging at least 3 two-way balancing transformers in a partially split tree, wherein the partially split tree arrangement divides current in a balanced manner from a single current path to at least four current paths, wherein at least one two-way balancing transformer is operatively coupled to first ends of two or more lamp loads and at least another two-way balancing transformer is operatively coupled to second ends of another two or more lamp loads; and

operatively coupling the at least four current paths to the at least 4 lamp loads to parallel the lamp loads.

22. The method as defined in claim 21, further comprising incorporating a safety winding in the two-way balancing transformers and electrically coupling the safety winding to anti-parallel diodes.

23. The method as defined in claim 21, further comprising winding the balancing windings for the two-way balancing transformers in separate windings.

24. An assembly of negative-impedance gas-discharge lamp loads comprising:

a plurality of at least 4 lamp loads; and

means for arranging two-way balancing transformers in a partially split tree, where the partially split tree of two-way balancing transformer is operatively coupled to the plurality of at least 4 lamp loads to divide current evenly among the lamp loads.

25. The assembly as defined in claim 24, wherein the assembly is substantially floating with respect to ground.

26. An assembly of negative-impedance gas-discharge lamp loads comprising:

a plurality of lamp loads, where the lamp loads each have a first end and a second end;

a first terminal and a second terminal for receiving power from at least one inverter transformer for driving the plurality of lamp loads in parallel;

a first plurality of balancing transformers operatively coupled between the first end of the plurality of lamp loads and the first terminal; and

a second plurality of balancing transformers operatively coupled between the second end of the plurality of lamp loads and the second terminal.