Power converter employing a tapped inductor and integrated magnetics and method of operating the same

• US 20060197510A1
• Filed: 02/23/2006
• Published: 09/07/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Flextronics International USA Incorporated (Flex, Ltd.)
• Original Assignee: ColdWatt, Inc. (Flex, Ltd.)
• Inventors: Chandrasekaran, Sriram
• Granted Patent: US 7,176,662 B2
• Time in Patent Office: Days
• US Class Current: 323/222
• CPC Class Codes: H02M 1/0064 Magnetic structures combining different functions, e.g. storage, filtering or transformation
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power converter employing a tapped inductor and method of operating the same. In one embodiment, the power converter includes first and second tapped inductors including a tapped winding having a first section and a second section with a tap therebetween. The power converter also includes first and second active phase legs including a main switch series-coupled with an input node of the power converter and the first section of the tapped windings of the first and second tapped inductors, respectively. The first and second active phase legs also include an auxiliary switch interposed between the second section of the tapped windings of the first and second tapped inductors, respectively, and an output node of the power converter.

Claims

1. A power converter, comprising:

a first tapped inductor including a tapped winding having a first section and a second section with a tap therebetween;

a second tapped inductor including a tapped winding having a first section and a second section with a tap therebetween;

a first active phase leg including a main switch series-coupled with an input node of said power converter and said first section of said tapped winding of said first tapped inductor, said first active phase leg also including an auxiliary switch interposed between said second section of said tapped winding of said first tapped inductor and an output node of said power converter; and

a second active phase leg including a main switch series-coupled with an input node of said power converter and said first section of said tapped winding of said second tapped inductor, said second active phase leg also including an auxiliary switch interposed between said second section of said tapped winding of said second tapped inductor and an output node of said power converter.

2. The power converter as recited in claim 1 wherein said auxiliary switch of at least one of said first and second active phase legs is selected from the group consisting of:

a metal-oxide semiconductor field-effect transistor; and

a diode.

3. The power converter as recited in claim 1 wherein said auxiliary switch of at least one of said first and second active phase legs operates as a synchronous rectifier for said power converter.

4. The power converter as recited in claim 1 wherein said main switch of said first active phase leg is interposed between said input node of said power converter and said first section of said tapped winding of said first tapped inductor.

5. The power converter as recited in claim 1 wherein said main and auxiliary switches of at least one of said first and second active phase legs conduct in a substantially complementary manner.

6. The power converter as recited in claim 1 wherein at least one of said first and second tapped inductors is a matrix integrated magnetic device.

7. The power converter as recited in claim 1 wherein at least one of said first and second tapped inductors includes a magnetic core having a common leg with an air gap and at least one outer leg.

8. The power converter as recited in claim 1 wherein said first tapped inductor includes a magnetic core having a common leg and at least one outer leg, said first and second winding sections of said tapped winding thereof being coupled pairs about at least one of said outer legs.

9. The power converter as recited in claim 1 wherein a reluctance of a magnetic path coupling said first and second winding sections of said tapped winding of said first tapped inductor is less than a reluctance of a common magnetic flux return path thereof.

10. The power converter as recited in claim 1 wherein a duty cycle associated with said main and auxiliary switches of said second active phase leg is delayed from a duty cycle associated with said main and auxiliary switches of said first active phase leg substantially inversely proportional to a number of active phase legs of said power converter.

11. A method of operating a power converter having an input node coupled to a source of electrical power and an output node, comprising:

providing a first tapped inductor including a tapped winding having a first section and a second section with a tap therebetween;

providing a second tapped inductor including a tapped winding having a first section and a second section with a tap therebetween;

controlling a main switch of said first active phase leg to induce an input current from said source of electrical power in said tapped winding of said first active phase leg;

operating an auxiliary switch of said first active phase leg to provide an output current to said output node via said second section of said tapped winding of said first tapped inductor;

controlling a main switch of said second active phase leg to induce an input current from said source of electrical power in said tapped winding of said second active phase leg; and

operating an auxiliary switch of said second active phase leg to provide an output current to said output node via said second section of said tapped winding of said second tapped inductor.

12. The method as recited in claim 11 wherein said auxiliary switch of at least one of said first and second active phase legs is selected from the group consisting of:

a metal-oxide semiconductor field-effect transistor; and

a diode.

13. The method as recited in claim 11 wherein said auxiliary switch of at least one of said first and second active phase legs operates as a synchronous rectifier for said power converter.

14. The method as recited in claim 11 wherein said main switch of said first active phase leg is interposed between said input node of said power converter and said first section of said tapped winding of said first tapped inductor.

15. The method as recited in claim 11 wherein said main and auxiliary switches of at least one of said first and second active phase legs conduct in a substantially complementary manner.

16. The method as recited in claim 11 wherein at least one of said first and second tapped inductors is a matrix integrated magnetic device.

17. The method as recited in claim 11 wherein at least one of said first and second tapped inductors includes a magnetic core having a common leg with an air gap and at least one outer leg.

18. The method as recited in claim 11 wherein said first tapped inductor includes a magnetic core having a common leg and at least one outer leg, said first and second winding sections of said tapped winding thereof being coupled pairs about at least one of said outer legs.

19. The method as recited in claim 11 wherein a reluctance of a magnetic path coupling said first and second winding sections of said tapped winding of said first tapped inductor is less than a reluctance of a common magnetic flux return path thereof.

20. The method as recited in claim 11 wherein a duty cycle associated with said main and auxiliary switches of said second active phase leg is delayed from a duty cycle associated with said main and auxiliary switches of said first active phase leg substantially inversely proportional to a number of active phase legs of said power converter.