DC transformer with an output inductance integrated on a magnetic core thereof and a DC/DC converter employing the same

• US 7,375,607 B2
• Filed: 09/30/2004
• Issued: 05/20/2008
• Est. Priority Date: 04/30/2004
• Status: Expired due to Fees

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Fan-Chiang, Chau-Tung, Lee, Chi-Hsiung
• Primary Examiner(s): Nguyen; Tuyen T.
• Application Number:
  US10/955,125
• Publication Number:
  US 20050243582A1
• Time in Patent Office: 1,328 Days
• Field of Search: 336/65, 336/83, 336/165, 336/170, 336/178, 363/13, 363/17, 363/47, 363/50, 363/153, 363/171
• US Class Current: 336/178
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 30/04 having two or more secondary windings, each supplying a separate load, e.g. for radio set power supplies
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Abstract

A DC/DC converter includes an input filter, a half-bridge converter without PWM (Pulse Width Modulation) control function, a synchronous rectifier, an output capacitor, and a DC transformer. The DC transformer includes a magnetic core, a primary winding, a first secondary winding, and a second secondary winding. The magnetic core of the DC transformer includes a first leg, a second leg having a first air gap, and a third leg having a second air gap. The first secondary winding is wound on the first leg and the second leg, and induces a first inductance by the first air gap. The second secondary winding is wound on the first leg and the third leg, and induces a second inductance by the second air gap.

Claims

1. A DC transformer comprising:

a magnetic core comprising a first leg, a second leg having a first air gap, and a third leg having a second air gap;

a primary winding wound around the magnetic core;

a first secondary winding wound around the first leg and the second leg for generating a first inductance by the first air gap of the magnetic core; and

a second secondary winding wound around the first leg and the third leg for generating a second inductance by the second air gap of the magnetic core, wherein the number of windings of the first secondary winding wound around the first leg is more than the number of windings of the first secondary winding wound around the second leg, and the number of windings of the second secondary winding wound around the first leg is more than the number of windings of the second secondary winding wound around the third leg.

2. The DC transformer of claim 1, wherein the dimension of each air gap of the magnetic core is between 0.02 and 0.07 mm.

3. The DC transformer of claim 1, wherein the magnetic core is of an EE, EI, EQ or RM type.

4. The DC transformer of claim 1, wherein the primary winding is wound around the first leg.

5. The DC transformer of claim 1, wherein the first leg comprises a third air gap.

6. The DC transformer of claim 1, wherein the first leg has no air gap.

7. The DC transformer of claim 1, wherein the first leg is located between the second leg and the third leg.

8. The DC transformer of claim 1, further comprising two outputs from the first secondary winding and the second secondary winding respectively.

9. The DC transformer of claim 1, wherein the first secondary winding is wound half turn on the second leg, and the second secondary winding is wound half turn on the third leg.

10. A DC transformer comprising:

a magnetic core comprising a first leg, a second leg having a first air gap, and a third leg having a second air gap;

a primary winding wound around the magnetic core to receive an input voltage;

a first secondary winding wound around the first leg, and around the second leg for generating a first inductance by the first air gap of the magnetic core to output a first part of an output voltage; and

a second secondary winding wound around the first leg, and around the third leg for generating a second inductance by the second air gap of the magnetic core to output a second part of the output voltage.

11. The DC transformer of claim 10, wherein the number of windings of the first secondary winding wound around the first leg is more than the number of windings of the first secondary winding wound around the second leg, and the number of windings of the second secondary winding wound around the first leg is more than the number of windings of the second secondary winding wound around the third leg.

12. The DC transformer of claim 10, wherein the first inductance is an equivalent inductance of the second inductance.

13. The DC transformer of claim 10, wherein the first secondary winding is wound half turn on the second leg, and the second secondary winding is wound half turn on the third leg.