Integrated magnetics for a DC-DC converter with flexible output inductor

• US 7,034,647 B2
• Filed: 10/15/2002
• Issued: 04/25/2006
• Est. Priority Date: 10/12/2001
• Status: Expired due to Fees

• Current Assignee: Northeastern University
• Original Assignee: Northeastern University
• Inventors: Qu, Dayu, Lehman, Bradley, Yan, Liang
• Primary Examiner(s): MAI, ANH T
• Application Number:
  US10/492,238
• Publication Number:
  US 20040189432A1
• Time in Patent Office: 1,288 Days
• Field of Search: 336/170, 336/178, 336/212, 336180-182, 336/12, 336/5, 361/17, 361/132, 363/17, 363/132
• US Class Current: 336/212
• CPC Class Codes: H01F 2038/026 non-linear inductive arrangements for converters, e.g. with additional windings
• CPC Class Codes: H01F 27/38 Auxiliary core members; Auxiliary coils or windings
• CPC Class Codes: H01F 37/00 Fixed inductances not covered by group H01F17/00
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• 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: H02M 3/337 in push-pull configuration H02M3/33576 takes precedence; with self-oscillating arrangements H02M3/3382, H02M3/3385

Abstract

An integrated magnetic assembly that allows the primary and secondary windings of a transformer and a separate inductor winding to be integrated on a unitary magnetic structure is disclosed. The unitary magnetic structure includes first, second, and third legs that are physically connected and magnetically coupled. The primary and secondary windings of the transformer can be formed on the third leg of the unitary magnetic structure. Alternatively, the primary and secondary windings can be split between the first and second legs. Thus, the primary winding includes first and second primary windings disposed on the first and second legs and the secondary winding includes first and second secondary windings disposed on the first and second legs. The inductor winding may also be formed either on the third leg or it may split into first and second inductor windings and disposed on the first and second legs. In addition, one or more legs may include an energy storage component such as an air gap. This integration of the primary and secondary windings and the inductor winding on the unitary magnetic structure advantageously decouples the inductor function from the transformer function and allows the more optimal design of both the inductor and the transformer. The unitary magnetic structure may be coupled to a full bridge, a half bridge, or a push pull voltage input source to form a DC—DC converter.

Claims

1. An integrated magnetic assembly comprising:

a unitary magnetic structure including a first leg, a second leg and a third leg that are all magnetically coupled and physically connected together;

a primary winding disposed on at least one leg of the unitary magnetic structure and magnetically coupled thereto;

a secondary winding disposed on at least one leg of the unitary magnetic structure and wherein the primary and secondary windings are magnetically coupled to one another via the unitary magnetic structure, the secondary winding including first and second output connections; and

an inductor winding disposed on at least one leg of the unitary magnetic structure, the inductor having a first connection electrically connected to the second connection of the secondary winding, the inductor having a second connection providing an inductor output.

2. The integrated magnetic assembly of claim 1 wherein the third leg is disposed between the first and second legs of the unitary magnetic structure.

3. The integrated magnetic assembly of claim 1 wherein:

the primary winding includes a first primary winding disposed on the first leg and a second primary winding disposed on the second leg, the first and second primary windings being electrically connected in series;

the secondary winding includes a first secondary winding disposed on the first leg and a second secondary winding disposed on the second leg, wherein the first secondary winding is magnetically coupled to the first primary winding via the unitary magnetic structure and the second secondary winding is magnetically coupled to the second primary winding via the unitary magnetic structure, the first and second secondary windings each having a first and second connections, wherein the second connection of the first secondary winding is electrically connected to the second connection of the second secondary winding; and

the first connection of the inductor winding being electrically connected to the electrical connection between the second connections of the first and second secondary winding.

4. The integrated magnetic assembly of claim 3 wherein the first and second primary windings each have a corresponding orientation and the respective orientations have substantially opposite polarity with respect to one another.

5. The integrated magnetic assembly of claim 3 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor winding has a polarity that is substantially opposite to the polarity of the first and second secondary windings.

6. The integrated magnetic assembly of claim 3 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor windings has a polarity that has substantially the same polarity as the of the first and second secondary windings.

7. The integrated magnetic assembly of claim 3 wherein the inductor winding is disposed on the third leg of the unitary magnetic structure.

8. The integrated magnetic assembly of claim 3 wherein the inductor winding includes a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the second connection of the second inductor winding and wherein the second connection of the first inductor winding is electrically connected to the electrically interconnected second connections of the first and second secondary windings.

9. The integrated magnetic assembly of claim 3 wherein at least one leg of the unitary magnetic structure includes an energy storage component.

10. The integrated magnetic assembly of claim 9 wherein the energy storage component is an air gap.

11. The integrated magnetic structure of claim 9 wherein the first leg has a first cross-sectional area and the second leg has a second cross sectional area and the third leg has a third cross sectional area and wherein the energy storage component is a portion of the at least one leg that includes the energy storage component has a fourth cross sectional area that is smaller than the smallest of the first, second, and third cross sectional areas.

12. The integrated magnetic structure of claim 9 wherein the first legs is composed of a first material having a first permeance, the second legs is composed of a second material having a second permeance and the third leg is composed of a material having a third permeance, wherein the energy storage component is composed of a fourth material having a fourth permeance that is less than the smallest of the first, second, and third permeances.

13. The integrated magnetic assembly of claim 1 wherein:

the primary winding is disposed on the third leg; and

the secondary winding is disposed on the third leg, wherein the secondary winding is magnetically coupled to the primary winding via the unitary magnetic structure.

14. The integrated magnetic assembly of claim 13 wherein the inductor winding includes a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the first connection of the secondary winding and the second connection of the first inductor winding is electrically connected to the second connection of the second inductor winding, and the first connection of the second inductor winding is electrically connected to the second connection of the secondary winding.

15. The integrated magnetic assembly of claim 13 wherein at least one leg of the unitary magnetic structure includes an energy storage component.

16. The integrated magnetic assembly of claim 13 wherein the energy storage component is an air gap.

17. The integrated magnetic structure of claim 16 wherein the first leg has a first cross-sectional area and the second leg has a second cross sectional area and the third leg has a third cross sectional area and wherein the energy storage component is a portion of the at least one leg that includes the energy storage component has a fourth cross sectional area that is smaller than the smallest of the first, second, and third cross sectional areas.

18. The integrated magnetic structure of claim 16 wherein the first legs is composed of a first material having a first permeance, the second legs is composed of a second material having a second permeance and the third leg is composed of a material having a third permeance, wherein the energy storage component is composed of a fourth material having a fourth permeance that is less than the smallest of the first, second, and third permeances.

19. The integrated magnetic assembly of claim 1 wherein:

the primary winding includes a first primary winding disposed on the first leg and a second primary winding disposed on the second leg, the first and second primary windings being electrically connected in series;

the secondary winding disposed on the third leg, the secondary winding including first and second connections;

the inductor winding including a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the first connection of the secondary winding and wherein the second connection of the first inductor winding is electrically connected to the second connection of the second inductor winding and wherein the first connection of the second inductor winding is electrically connected to the second connection of the secondary winding.

20. The integrated magnetic assembly of claim 1 wherein:

the primary winding disposed on the third leg;

the secondary winding including a first secondary winding disposed on the first leg and a second secondary winding disposed on the second leg, wherein the first and second secondary windings are magnetically coupled to the primary winding via the unitary magnetic structure, the first and second secondary windings each having a first and second connections, wherein the second connection of the first secondary winding is electrically connected to the first connection of the second secondary winding; and

the inductor winding includes a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the first connection of the first secondary winding and the second connection of the first inductor winding is electrically connected to the second connection of the second inductor winding and wherein the first connection of the second inductor winding is electrically connected to the second connection of the second secondary coil.

21. A DC—

DC converter comprising;

an integrated magnetic assembly comprising;

a unitary magnetic structure including a first leg, a second leg and a third leg that are all magnetically coupled and physically connected together;

a primary winding including a first primary winding disposed on the first leg and a second primary winding disposed on the second leg, the first and second primary windings being electrically connected in series;

a secondary winding including a first secondary winding disposed on the first leg and a second secondary winding disposed on the second leg, wherein the first secondary winding is magnetically coupled to the first primary winding via the unitary magnetic structure and the second secondary winding is magnetically coupled to the second primary winding via the unitary magnetic structure, the first and second secondary windings each having first and second connections, wherein the second connection of the first secondary winding is electrically connected to the second connection of the second secondary winding;

an inductor winding disposed on at least one leg of the unitary magnetic structure, the inductor having a first connection electrically connected to the electrically connected second connections of the first and second secondary windings, the inductor having a second connection;

a first rectifier having an input and output, the input of the first rectifier being electrically connected to the first connection of the first secondary winding;

a second rectifier having an input and output, the input of the first rectifier being electrically connected to the first connection of the second secondary winding;

the outputs of the first and second rectifiers electrically connected together to form a first output terminal and the second connection of the inductor forming a second output terminal, where in a signal provided on the first output terminal and a signal provided on the second output terminal will have substantially opposite polarities; and

an input voltage source electrically connected across the primary winding.

22. The DC—

DC converter of claim 21 wherein the first and second primary windings each have a corresponding polarity and the respective polarities are substantially opposite with respect to one another.

23. The DC—

DC converter of claim 21 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor winding has an polarity that is substantially opposite in polarity to the of the first and second secondary windings.

24. The DC—

DC converter of claim 21 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor windings has an polarity that has substantially the same polarity as the the first and second secondary windings.

25. The DC—

DC converter of claim 21 wherein the inductor winding is disposed on the third leg of the unitary magnetic structure.

26. The DC—

DC converter of claim 21 wherein the inductor winding includes a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the second connection of the second inductor winding and wherein the second connection of the first inductor winding is electrically connected to the electrically interconnected second connections of the first and second secondary windings.

27. The DC—

DC converter of claim 21 wherein the third leg of the unitary magnetic structure includes an energy storage component.

28. The DC—

DC converter of claim 27 wherein the energy storage component is an air gap.

29. The DC—

DC converter of claim 21 wherein the input voltage source is a full bridge voltage inverter.

30. The DC—

DC converter of claim 21 wherein the input voltage source is a half-bridge converter.

31. The DC—

DC converter of claim 21 further including a capacitor electrically connected between the first output terminal and the second connection of the inductor winding, wherein the output is provided across the capacitor.

32. A DC—

DC converter comprising;

an integrated magnetic assembly comprising;

a unitary magnetic structure including a first leg, a second leg and a third leg that are all magnetically coupled and physically connected together;

a primary winding including first and second primary windings disposed on the first and second legs respectively and third and fourth primary windings disposed on the first and second legs respectively, the first and second primary windings being electrically connected in series and the third and fourth primary windings being electrically connected in series;

a secondary winding including a first secondary winding disposed on the first leg and a second secondary winding disposed on the second leg, wherein the first secondary winding is magnetically coupled to the first and third primary windings via the unitary magnetic structure and the second secondary winding is magnetically coupled to the second and fourth primary winding via the unitary magnetic structure, the first and second secondary windings each having first and second connections, wherein the second connection of the first secondary winding is electrically connected to the second connection of the second secondary winding;

an inductor winding disposed on at least one leg of the unitary magnetic structure, the inductor having a first connection electrically connected to the electrically connected second connections of the first and second secondary windings, the inductor having a second connection;

a first rectifier having an input and output, the input of the first rectifier being electrically connected to the first connection of the first secondary winding;

a second rectifier having an input and output, the input of the first rectifier being electrically connected to the first connection of the second secondary winding;

the outputs of the first and second rectifiers electrically connected together to form a first output terminal and the second connection of the inductor forming a second output terminal, where in a signal provided on the first output terminal and a signal provided on the second output terminal will have substantially opposite polarities; and

a push-pull voltage source having first, second, and third, connections, wherein the first and third connections are electrically connected across the first and second primary windings and the second and first connections are electrically connected across the third and fourth primary windings.

33. The DC—

DC converter of claim 32 wherein the first and second primary windings each have a corresponding polarity and the respective polarities are substantially opposite with respect to one another and wherein the third and fourth primary windings each have a corresponding polarity and the respective polarities are substantially opposite with respect to one another.

34. The DC—

DC converter of claim 32 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor winding has an polarity that is substantially opposite in to the polarity of the first and second secondary windings.

35. The DC—

DC converter of claim 32 wherein the first and second secondary windings have a corresponding polarity and the respective polarities are substantially the same with respect to one another and wherein the inductor windings has an polarity that has substantially the same polarity as the the first and second secondary windings.

36. The DC—

DC converter of claim 32 wherein the inductor winding is disposed on the third leg of the unitary magnetic structure.

37. The DC—

DC converter of claim 32 wherein the inductor winding includes a first inductor winding disposed on the first leg and a second inductor winding disposed on the second leg, wherein each of the first and second inductor windings includes first and second connections and wherein the first connection of the first inductor winding is electrically connected to the second connection of the second inductor winding and wherein the second connection of the first inductor winding is electrically connected to the electrically interconnected second connections of the first and second secondary windings.