Zero voltage switching DC-DC converter

• US 20020034083A1
• Filed: 10/10/2001
• Published: 03/21/2002
• Est. Priority Date: 09/01/1999
• Status: Active Grant

• Current Assignee: Ned Mohan, Rajapandian Ayyanar
• Original Assignee: Ned Mohan, Rajapandian Ayyanar
• Inventors: Ayyanar, Rajapandian, Mohan, Ned
• Granted Patent: US 6,611,444 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer

Abstract

A DC-DC power converter includes input terminals and a rectifier circuit. An additional circuit is connected to the input terminals and the rectifier. The latter circuit is adapted to generate a varying voltage at output terminals of the rectifier that varies in amplitude from a maximum voltage value to a non-zero voltage value between the maximum voltage value and zero.

Claims

1. A power converter comprising:

a first pair of switching elements connected across a first input terminal and a second input terminal forming a first node;

a second pair of switching elements connected across the first input terminal and the second input terminal forming a second node;

a first transformer having a primary winding connected across the first and second nodes, and a secondary winding;

a third pair of electrical elements connected across the first input terminal and the second input terminal forming a third node;

a second transformer having a primary winding connected across the second and third nodes, and a secondary winding;

a rectifier connected to the secondary windings of the first and second transformers; and

a filter connected to the rectifier having output terminals.

2. The power converter of claim 1 wherein the third pair of electrical elements comprise capacitors.

3. The power converter of claim 1 wherein the third pair of electrical elements comprise switching elements.

4. The power converter of claim 1 and further comprising an inductor connected across the first and third nodes.

5. The power converter of claim 1 wherein the secondary windings are connected in series.

6. A power converter comprising:

a first pair of switching elements connected across a first input terminal and a second input terminal forming a first node;

a second pair of switching elements connected across the first input terminal and the second input terminal forming a second node;

a first transformer having a primary winding connected across the first and second nodes, and a secondary winding with a first end connected to the second node;

a third pair of electrical elements connected across the first input terminal and the second input terminal forming a third node;

a second transformer having a primary winding with a first end connected to the third node and a second end connected to a second end of the secondary winding of the first transformer, the second transformer having a secondary winding;

a rectifier connected to the secondary winding of the second transformer; and

a filter connected to the rectifier having output terminals.

7. The power converter of claim 6 wherein the second transformer includes a plurality of secondary windings connected to the rectifier.

8. The power converter of claim 7 wherein the rectifier comprises a half-bridge rectifier.

9. The power converter of claim 8 wherein the plurality of secondary windings of the second transformer form a center-tapped secondary winding.

10. A power converter comprising:

a first pair of switching elements connected across a first input terminal and a second input terminal forming a first node;

a second pair of switching elements connected across the first input terminal and the second input terminal forming a second node;

a first transformer having a primary winding connected across the first and second nodes, and a secondary winding;

a third pair of switching elements connected across the first input terminal and the second input terminal forming a third node;

a fourth pair of electrical elements connected across the first input terminal and the second input terminal forming a fourth node;

a second transformer having a primary winding connected across the third and fourth nodes, and a secondary winding;

a rectifier connected to the secondary windings of the first and second transformers; and

a filter connected to the rectifier having output terminals.

11. The power converter of claim 10 wherein the fourth pair of electrical elements comprise capacitors.

12. The power converter of claim 10 wherein the secondary windings are connected in series.

14. The power converter of claim 13 wherein each of the switching elements are operated at a 50 percent duty-ratio.

15. The power converter of claim 13 wherein the third pair of electrical elements comprise capacitors.

16. The power converter of claim 13 wherein the third pair of electrical elements comprise switching elements.

18. The power converter of claim 17 wherein the second circuit portion comprises a full-bridge circuit comprising a first and second branch of series connected switching elements and a second branch of series connected switching elements connected across the first and second input terminals, and a transformer having a primary winding and a secondary winding, the primary winding being connected across the first and second branches at nodes formed at each of the series connected switching elements and the secondary winding being operably connected to the first and second output terminals.

19. The power converter of claim 18 wherein the first circuit portion comprises a half-bridge circuit comprising the first branch of series connected switching elements and a third branch of series connected capacitors connected across the first and second input terminals, and a second transformer having a primary winding and a secondary winding, the primary winding being connected across the node of the first branch of switching elements and a node formed at the series connected capacitors and the secondary winding being operably connected to the first and second output terminals.

20. The power converter of claim 18 wherein the first circuit portion comprises a full-bridge circuit comprising the first branch of series connected switching elements and a third branch of series connected switching elements connected across the first and second input terminals, and a second transformer having a primary winding and a secondary winding, the primary winding being connected across the node of the first branch of switching elements and a node formed at the series connected switching elements of the third branch and the secondary winding being operably connected to the first and second output terminals.

13. A power converter comprising:

a full-bridge converter section comprising;

a first pair of switching elements connected across a first input terminal and a second input terminal forming a first node;

a second pair of switching elements connected across the first input terminal and the second input terminal forming a second node;

a third pair of electrical elements connected across the first input terminal and the second input terminal forming a third node, wherein the second pair of switching elements and the third pair of electrical elements form an uncontrolled second bridge converter section having a square wave output;

a rectifier connected to receive output signals from the full-bridge converter section and the second converter section;

a filter connected to receive output signals from the rectifier and having output terminals; and

a controller providing control signals to adjust a phase difference between signals at the first and second nodes.

17. A DC-DC power converter having first and second input terminals and first and second output terminals, the power converter comprising:

a first circuit portion connected across the first and second input terminals, the first circuit portion capable of providing a minimum selected output power signal at the first and second output terminals; and

a second circuit portion connected across the first and second input terminals and to the first circuit portion to selectively contribute to an output power signal of the first circuit portion.

21. A DC-DC power converter comprising:

input terminals;

a rectifier circuit; and

circuit means connected to the input terminals and the rectifier, the circuit means adapted for generating a varying voltage at output terminals of the rectifier that varies in amplitude from a maximum voltage value to a non-zero voltage value between the maximum voltage value and zero.

22. The DC-DC power converter of claim 21 wherein the circuit means is adapted for drawing a varying current through the input terminals that varies in amplitude from a maximum current value to a non-zero current value between the maximum current value and zero and adapted.

23. The DC-DC power converter of claim 21 wherein the circuit means is adapted for regulating the output voltage at a constant value.

24. The DC-DC power converter of claim 21 wherein the circuit means is adapted for regulating the output voltage over a range.

25. The DC-DC power converter of claim 21 wherein the circuit means includes:

a first circuit portion connected across the input terminals, the first circuit portion capable of providing a minimum selected output power signal; and

a second circuit portion connected across the input terminals and to the first circuit portion to selectively contribute to an output power signal of the first circuit portion.

26. The DC-DC power converter of claim 22 wherein the circuit means includes:

a first pair of switching elements connected across the input terminals forming a first node;

a second pair of electrical elements connected across the input terminals forming a second node;

a transformer having a primary winding connected across the first and second nodes, and a secondary windings comprising;

a center tapped winding having a center tap and remote ends; and

a pair of additional windings, wherein an additional winding is connected to each remote end; and

wherein the rectifying circuit is connected to the pair of additional windings and includes switching elements.

27. The DC-DC power converter of claim 23 wherein the circuit means includes:

a first pair of switching elements connected across the input forming a first node;

a second pair of switching elements connected across the input terminals forming a second node;

a first transformer having a primary winding connected across the first and second nodes, and a secondary winding;

a third pair of electrical elements connected across the first input terminal and the second input terminal forming a third node;

a second transformer having a primary winding connected across the second and third nodes, and a secondary winding; and

wherein the rectifying circuit is connected to the secondary windings of the first and second transformers.