Multiphase soft switched DC/DC converter and active control technique for fuel cell ripple current elimination

• US 7,518,886 B1
• Filed: 10/13/2005
• Issued: 04/14/2009
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: Virginia Tech Intellectual Properties, Inc.
• Original Assignee: Virginia Tech Intellectual Properties, Inc.
• Inventors: Ridenour, Amy, Liu, Changrong, Lai, Jih-Sheng
• Primary Examiner(s): Ullah; Akm E
• Assistant Examiner(s): BEHM, HARRY RAYMOND
• Application Number:
  US11/249,945
• Time in Patent Office: 1,279 Days
• Field of Search: 363/17, 363/65, 363/71, 363/21.03, 363/46, 363/69, 363/70, 363/21.02, 363/45, 363/67, 363/98, 363/132
• US Class Current: 363/17
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02P 8/12 Control or stabilisation of current

Abstract

DC/DC converter has a transformer having primary coils connected to an input side and secondary coils connected to an output side. Each primary coil connects a full-bridge circuit comprising two switches on two legs, the primary coil being connected between the switches on each leg, each full-bridge circuit being connected in parallel wherein each leg is disposed parallel to one another, and the secondary coils connected to a rectifying circuit. An outer loop control circuit that reduces ripple in a voltage reference has a first resistor connected in series with a second resistor connected in series with a first capacitor which are connected in parallel with a second capacitor. An inner loop control circuit that reduces ripple in a current reference has a third resistor connected in series with a fourth resistor connected in series with a third capacitor which are connected in parallel with a fourth capacitor.

Claims

1. A fuel cell power management structure comprising:

a. a multiphase soft switch DC/DC converter comprising;

i. a transformer, an input side connected to a power source, and an output side connected to an output filter,

ii. said transformer having a plurality of primary coils connected to said input side and a plurality of secondary coils connected to said output side,

iii. wherein each primary coil connects a full-bridge circuit and each full-bridge circuit comprises two switches on two legs,

iv. said primary coil being connected between said switches on each leg of the full bridge circuit,

v. each full-bridge circuit being connected in parallel to each other such that each leg is disposed parallel to one another and to said power source, and

vi. said secondary coils connected to a rectifying circuit; and

b. a ripple reduction control circuit comprising;

i. an outer loop control circuit disposed parallel to said DC/DC converter for reducing ripple in a voltage reference.

2. The fuel cell power management structure of claim 1, wherein:

the multiphase soft switch DC/DC converter further comprises at least one capacitor in parallel with said power source.

3. The fuel cell power management structure of claim 1, wherein:

the multiphase soft switch DC/DC converter further comprises a plurality of capacitors equivalent to the number of primary coils wherein each capacitor is connected in parallel with each half bridge circuit.

4. The fuel cell power management structure of claim 1, wherein:

the multiphase soft switch DC/DC converter further comprising;

a leakage inductor connected to said primary coil.

5. The fuel cell power management structure of claim 1, wherein:

each of said secondary coils further connected to a leg between two diodes each leg disposed parallel to one another with the load disposed across.

6. The fuel cell power management structure of claim 1, wherein:

there are n primary coils and n secondary coils wherein n is an integer greater than or equal to 2.

7. The fuel cell power management structure of claim 1, wherein:

there are three secondary coils having a wye coil configuration.

8. The fuel cell power management structure of claim 6, wherein:

n is equal to three.

9. The fuel cell power management structure of claim 8, wherein:

the multiphase soft switch DC/DC converter further comprises a control circuit operable for controlling each full-bridge circuit with a phase shift in the range of 120-180 degrees.

10. The fuel cell power management structure of claim 6, wherein:

the multiphase soft switch DC/DC converter further comprises a control circuit operable for controlling each full-bridge circuit with a phase shift in the range l degrees to h degrees wherein l is equivalent to 360 degrees divided by n and h is equivalent to l plus 60 degrees.

11. The fuel cell power management structure of claim 6, wherein:

the control circuit, further comprises;

an inner loop control circuit for reducing ripple in a current reference.

12. A method for operating an n phase power converter, comprising:

a. providing an n phase soft switch DC/DC converter,

wherein the n phase soft switch DC/DC converter comprises;

i. a transformer, an input side connected to a power source, and an output side connected to an output filter,

ii. said transformer having a plurality of primary coils connected to said input side and a plurality of secondary coils connected to said output side,

iii. wherein each primary coil connects a full-bridge circuit and each full-bridge circuit comprises two switches on two legs,

iv. said primary coil being connected between said switches on each leg of the full bridge circuit,

v. each full-bridge circuit being connected in parallel to each other such that each leg is disposed parallel to one another and to said power source, and

vi. said secondary coils connected to a rectifying circuit;

b. operating each individual full-bridge circuit with a phase shift in the range l degrees to h degrees wherein l is equivalent to 360 degrees divided by n and h is equivalent to l plus 60 degrees.

13. The method of claim 12, wherein:

the multiphase soft switch DC/DC converter further comprises at least one capacitor in parallel with said power source.

14. The method of claim 12, wherein:

the multiphase soft switch DC/DC converter further comprises a plurality of capacitors equivalent to the number of primary coils wherein each capacitor is connected in parallel with each half bridge circuit.

15. The method of claim 12, wherein:

the multiphase soft switch DC/DC converter further comprising;

a leakage inductor connected to said primary coil.

16. The method of claim 12, wherein:

each of said secondary coils further connected to a leg between two diodes each leg disposed parallel to one another with the load disposed across.

17. The method of claim 12, wherein:

there are n primary coils and n secondary coils wherein n is an integer greater than or equal to 2.

18. The method of claim 17, wherein:

there are three secondary coils having a wye coil configuration.

19. The method of claim 17, wherein:

n is equal to three.

20. The method of claim 19, wherein:

the phase shift is in the range of 120-180 degrees.

21. The method of claim 12 further comprising:

a ripple reduction control circuit, comprising;

an outer loop control circuit with a first outer loop pole and a second outer loop pole for reducing ripple in a voltage reference.

22. The method of claim 21, wherein:

the control circuit further comprises;

an inner loop control circuit with a first inner loop pole and a second inner loop pole for reducing ripple in a current reference.