Transformer with split primary winding

• US 8,847,719 B2
• Filed: 09/30/2008
• Issued: 09/30/2014
• Est. Priority Date: 07/25/2008
• Status: Expired due to Fees

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John L., Gaetano, Mauro L.
• Primary Examiner(s): Chan, Tsz
• Application Number:
  US12/241,973
• Publication Number:
  US 20100019874A1
• Time in Patent Office: 2,191 Days
• Field of Search: 336/145, 336/178, 336180-182, 336/184, 336/198, 336/212, 336/214, 336/215
• US Class Current: 336/178
• CPC Class Codes: H01F 2038/026 non-linear inductive arrangements for converters, e.g. with additional windings
• CPC Class Codes: H01F 3/10 Composite arrangements of magnetic circuits
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 38/02 for non-linear operation
• CPC Class Codes: H01F 38/08 High-leakage transformers or inductances
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• 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 transformer includes a core having a first leg, a second leg and a third leg, a split primary winding including first turns about the first leg electrically coupled with second turns about the third leg, and a secondary winding about the second leg. Magnetic flux linking the first turns of the split primary winding and magnetic flux linking the second turns of the primary winding link the secondary winding.

Claims

1. A transformer, comprising:

a core having a first leg, a second leg and a third leg, wherein at least the second leg has an air gap therein;

a split primary winding including first turns about the first leg electrically coupled with second turns about the third leg; and

a secondary winding about the second leg, wherein magnetic flux linking the first turns of the split primary winding and magnetic flux linking the second turns of the split primary winding are additive in the second leg and link the secondary winding.

2. The transformer of claim 1, wherein the first turns and the second turns of the split primary winding are electrically connected in parallel.

3. The transformer of claim 1, wherein the first turns and the second turns of the split primary winding are electrically connected in series.

4. The transformer of claim 1, wherein a first number of the first turns is different than a second number of the second turns.

5. The transformer of claim 4, wherein a third number of turns of the secondary winding is less than the first and second numbers of turns.

6. The transformer of claim 1, wherein:

the air gap is a first air gap; and

at least one of a set including the first and second legs has a second air gap therein.

7. The transformer of claim 6, wherein the first air gap is larger than the second air gap.

8. The transformer of claim 1, and further comprising insulation disposed between the first turns and the secondary winding and disposed between the second turns and the secondary winding.

9. The transformer of claim 1, and further comprising first, second and third bobbins disposed on the first, second and third legs, respectively, wherein:

the first turns are wound about the first bobbin;

the second turns are wound about the third bobbin; and

the secondary winding is wound about the second bobbin.

10. The transformer of claim 1, wherein the second leg is a center leg disposed between the first and third legs.

11. The transformer of claim 1, wherein the core comprises an EE core.

12. A converter including a transformer in accordance with claim 1.

13. The transformer of claim 1, wherein:

the second leg is a center leg disposed between the first and third legs;

a first number of the first turns is different than a second number of the second turns; and

a third number of turns of the secondary winding is less than the first and second numbers of turns.

14. The transformer of claim 13, wherein:

the air gap is a first air gap; and

at least one of a set including the first and second legs has a second air gap therein.

15. A system, comprising:

a power supply including a transformer having;

a core having a first leg, a second leg and a third leg, wherein at least the second leg has an air gap therein;

a split primary winding including first turns about the first leg electrically coupled with second turns about the third leg; and

a secondary winding about the second leg, wherein magnetic flux linking the first turns of the split primary winding and magnetic flux linking the second turns of the split primary winding are additive in the second leg and link the secondary winding; and

a powered system electrically coupled to receive power from the power supply.

16. The system of claim 15, wherein:

the powered system includes a housing;

the power supply is internal to the housing.

17. The system of claim 15, wherein:

the powered system includes a housing;

the power supply is external to the housing.

18. The system of claim 15, wherein the first turns and the second turns of the split primary winding are electrically connected in parallel.

19. The system of claim 15, wherein the first turns and the second turns of the split primary winding are electrically connected in series.

20. The system of claim 15, wherein a first number of the first turns is different than a second number of the second turns.

21. The system of claim 20, wherein a third number of turns of the second secondary winding is less than the first and second numbers of turns.

22. The system of claim 15, wherein the second leg is a center leg disposed between the first and third legs.

23. The system of claim 15, wherein:

the second leg is a center leg disposed between the first and third legs;

a first number of the first turns is different than a second number of the second turns; and

a third number of turns of the secondary winding is less than the first and second numbers of turns.