Ripple canceling, soft switching isolated DC/DC converters with reduced voltage stress synchronous rectification

• US 6,445,599 B1
• Filed: 03/29/2001
• Issued: 09/03/2002
• Est. Priority Date: 03/29/2001
• Status: Expired due to Term

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Nguyen, Chien
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/820,956
• Time in Patent Office: 523 Days
• Field of Search: 323/222, 323/272, 363/24, 363/25, 363/26, 363/89
• US Class Current: 363/25
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current

Abstract

Ripple canceling, soft switching isolated DC/DC converters with reduced voltage stress synchronous rectification. The converters include interleaved switching converters providing power to a node supplying power to a zero volt switching bi-phase power conversion stage driving synchronous rectifiers feeding an output filter. In one embodiment, the interleaved converters are boost mode converters operating in continuous conduction mode boost converters. Various embodiments are disclosed.

Claims

1. A DC to DC converter comprising:

first and second interleaved DC to DC switching converters having a common output;

a transformer having an alternating input to its primary from the common output of the first and second interleaved DC to DC switching converters, the alternating input being synchronized with the interleaved switching converters; and

,

a balanced synchronous rectifier circuit coupled to a secondary of the transformer.

2. The DC to DC converter of claim 1 wherein the secondary of the transformer is a center tapped secondary having an inductor coupled to the center tap and forming one output of the converter, the synchronous rectifier circuit being coupled to the ends of the secondary of the transformer and providing a second output of the DC to DC converter.

3. The DC to DC converter of claim 1 further comprised of first and second inductors coupled in series across the secondary of the transformer, the common connection of the inductors forming one output of the DC to DC converter, the synchronous rectifier circuit providing a second output of the DC to DC converter being coupled to the secondary of the transformer.

4. The DC to DC converter of claim 1 wherein the first and second interleaved switching converters are boost mode interleaved switching converters.

5. The DC to DC converter of claim 4 wherein the first and second interleaved switching converters are boost mode continuous conduction interleaved switching converters.

6. The DC to DC converter of claim 4 wherein the alternating input to the transformer is synchronized to the trailing edge of the switching of the boost mode interleaved switching converters.

7. The DC to DC converter of claim 1 wherein the transformer primary is a center tapped primary, the output of the interleaved switching converters being coupled to the center tap, the ends of the primary winding being alternately coupled to a circuit ground through first and second switching transistors.

8. The DC to DC converter of claim 7 wherein the first and second switching transistors are switched using zero volt switching.

9. The DC to DC converter of claim 8 wherein the first and second switching transistors are MOS transistors.

10. The DC to DC converter of claim 8 wherein the switching of the first and second switching transistors is synchronized to the trailing edge of the switching of the interleaved switching converters.

11. A DC to DC converter comprising:

first and second interleaved boost mode DC to DC switching converters;

a transformer having an alternating input to its primary synchronized with the interleaved switching converters, and a center tapped secondary;

a balanced synchronous rectifier circuit; and

, the center tap of the secondary of the transformer being coupled through an inductor to form one output of the DC to DC converter, the synchronous rectifier circuit being coupled to the ends of the secondary of the transformer to provide a second output of the DC to DC converter.

12. The DC to DC converter of claim 11 wherein the first and second interleaved switching converters are boost mode continuous conduction converters.

13. The DC to DC converter of claim 12 wherein the alternating input to the transformer is synchronized to the trailing edge of the switching of the interleaved boost mode switching converters.

14. The DC to DC converter of claim 11 wherein the transformer primary is a center tapped primary, the output of the interleaved switching converters being coupled to the center tap, the ends of the primary winding being alternately coupled to a circuit ground through first and second switching transistors.

15. The DC to DC converter of claim 14 wherein the first and second switching transistors are switched using zero volt switching.

16. The DC to DC converter of claim 15 wherein the first and second switching transistors are MOS transistors.

17. The DC to DC converter of claim 15 wherein the switching of the first and second switching transistors is synchronized to the trailing edge of the switching of the interleaved switching converters.

18. A DC to DC converter comprising:

first and second interleaved boost mode DC to DC switching converters;

a transformer having an alternating input to its primary synchronized with the interleaved switching converters;

a balanced synchronous rectifier circuit; and

,

first and second inductors coupled in series across the secondary of the transformer, the common connection of the inductors forming one output of the DC to DC converter, the synchronous rectifier circuit being coupled to the secondary of the transformer to provide a second output of the DC to DC converter.

19. The DC to DC converter of claim 18 wherein the first and second interleaved switching converters are boost mode continuous conduction converters.

20. The DC to DC converter of claim 19 wherein the alternating input to the transformer is synchronized to the trailing edge of the switching of the interleaved boost mode switching converters.

21. The DC to DC converter of claim 18 wherein the transformer primary is a center tapped primary, the output of the interleaved switching converters being coupled to the center tap, the ends of the primary winding being alternately coupled to a circuit ground through first and second switching transistors.

22. The DC to DC converter of claim 21 wherein the first and second switching transistors are switched using zero volt switching.

23. The DC to DC converter of claim 22 wherein the first and second switching transistors are MOS transistors.

24. The DC to DC converter of claim 22 wherein the switching of the first and second switching transistors is synchronized to the trailing edge of the switching of the interleaved switching converters.

25. A method of converting a first DC voltage to a second DC voltage comprising:

operating first and second DC to DC switching converters in an interleaved manner;

coupling the output of the switching converters to the primary of a transformer in an alternating manner synchronized with the interleaved switching converters; and

, synchronously rectifying the output of the secondary of the transformer to provide an output at the second DC voltage.

26. The method of claim 25 wherein operating the first and second DC to DC switching converters in an interleaved manner comprises operating the first and second DC to DC switching converters in a pulse width modulated interleaved manner responsive to the second DC voltage.

27. The method of claim 26 wherein synchronously rectifying the output of the secondary of the transformer comprises coupling an inductor to a center tap of the secondary of the transformer to form a first converter output, and synchronously rectifying the output of the secondary of the transformer relative to the first converter output to form the second converter output.

28. The method of claim 26 wherein synchronously rectifying the output of the secondary of the transformer comprises coupling first and second inductors in series across the secondary of the transformer, and synchronously rectifying the output of the secondary of the transformer relative to the common connection of the inductors.

29. The method of claim 26 wherein operating the first and second DC to DC switching converters in an interleaved manner comprises operating first and second DC to DC boost mode switching converters in an interleaved manner.

30. The method of claim 26 wherein coupling the output of the switching converters to the primary of a transformer in an alternating manner synchronized with the interleaved switching converters comprises coupling the output of the switching converters to the primary of a transformer in an alternating manner synchronized with the trailing edge of the switching of the interleaved switching converters.

31. The method of claim 30 wherein the transformer primary is a center tapped primary, the output of the interleaved switching converters being coupled to the center tap, the ends of the primary winding being alternately coupled to a circuit ground through first and second switching transistors.

32. The method claim 31 wherein the first and second switching transistors are switched using zero volt switching.

33. The method claim 32 wherein the first and second switching transistors are MOS transistors.

34. The method of claim 32 wherein the switching of the first and second switching transistors is synchronized to the trailing edge of the switching of the interleaved switching converters.