Switching power supply with a snubber circuit

• US 7,130,203 B2
• Filed: 04/30/2002
• Issued: 10/31/2006
• Est. Priority Date: 04/30/2002
• Status: Expired due to Term

• Current Assignee: DET International Holding Limited (Delta Electronics Incorporated)
• Original Assignee: DET International Holding Limited (Delta Electronics Incorporated)
• Inventors: Mbaye, Fall
• Primary Examiner(s): Berhane, Adolf
• Application Number:
  US10/513,130
• Publication Number:
  US 20050259451A1
• Time in Patent Office: 1,645 Days
• Field of Search: 363/16, 363/55, 363/56.01, 363/56.06, 363/56.12, 363/131, 363/132, 363/133
• US Class Current: 363/56.12
• CPC Class Codes: H02M 3/337 in push-pull configuration H02M3/33576 takes precedence; with self-oscillating arrangements H02M3/3382, H02M3/3385

Abstract

A DC/DC power supply with two transformers (10, 20), which for example are connected in parallel on the primary and in series on the secondary side, comprises two passive, non-dissipative snubber circuits (1.1, 1.2). Each snubber circuit comprises a series circuit formed by a capacitor (3.1, 3.2) and a diode (4.4, 4.7), which is connected to the output capacitor (13) of the power supply. The transformers are interleaved with a push-pull configuration. On the secondary side, the power supply has an output choke (12, 22) and two output rectifiers (11, 21) are connected to the secondary winding (14, 24) of each transformer. Each snubber circuit further comprises two additional diodes (4.5, 4.6, 4.8, 4.9), one electrode of these diodes being connected to the joint electrode of the snubber capacitor (3.1, 3.2) and the first snubber diode (4.4, 4.7) and the other electrodes being connected respectively to an end of the secondary winding (14, 24) of a transformer.

Claims

1. A switching power supply providing a DC output, the power supply having an output capacitor, a transformer with a primary and a secondary winding and a first snubber circuit comprising a snubber capacitor and a first snubber diode, characterized in that the snubber capacitor and the first snubber diode are arranged in a series circuit which is connected in parallel to the output capacitor, wherein the snubber circuit further comprises a second and a third snubber diode, a first electrode of the second snubber diode and a first electrode of the third snubber diode being connected to a joint electrode of the first snubber diode and the snubber capacitor, a second electrode of the second snubber diode being connected to a first end of the secondary winding and a second electrode of the third snubber diode being connected to a second end of the secondary winding.

2. The switching power supply according to claim 1, wherein the power supply has, in operation, a DC input voltage and a DC output voltage.

3. The switching power supply according to claim 1, further comprising at least two alternately driven power switches connected to the primary winding.

4. The switching power supply according to claim 2, further comprising at least two alternately driven power switches connected to the primary winding.

5. The switching power supply according to claim 4, further comprising a second snubber circuit and a second transformer having a primary and a secondary winding, the primary windings of the transformers being connected in parallel, the secondary windings of the transformers being connected in series and the first snubber circuit being connected to the secondary winding of the first transformer and the second snubber circuit being connected to the secondary winding of the second transformer.

6. The switching power supply according to claim 5, wherein both snubber circuits comprise a snubber capacitor and a first, a second and a third snubber diode,

an anode of the first snubber diode of the first snubber circuit being connected to a first electrode of the output capacitor,

a cathode of the first snubber diode of the first snubber circuit being connected to a first electrode of the snubber capacitor of the first snubber circuit and a second electrode of the snubber capacitor of the first snubber circuit being connected to a second electrode of the output capacitor,

an anode of the second snubber diode of the first snubber circuit being connected to the cathode of the first snubber diode of the first snubber circuit and a cathode of the second snubber diode of the first snubber circuit being connected to a first end of the secondary winding of a first transformer,

an anode of the third snubber diode of the first snubber circuit being connected to the cathode of the first snubber diode of the first snubber circuit and a cathode of the third snubber diode of the first snubber circuit being connected to a second end of the secondary winding of the first transformer,

a cathode of the first snubber diode of the second snubber circuit being connected to the second electrode of the output capacitor,

an anode of the first snubber diode of the second snubber circuit being connected to a first electrode of the snubber capacitor of the second snubber circuit and a second electrode of the snubber capacitor of the second snubber circuit being connected to the first electrode of the output capacitor,

a cathode of the second snubber diode of the second snubber circuit being connected to the anode of the first snubber diode of the second snubber circuit and an anode of the second snubber diode of the second snubber circuit being connected to a first end of the secondary winding of a second transformer,

a cathode of the third snubber diode of the second snubber circuit being connected to the anode of the first snubber diode of the second snubber circuit and an anode of the third snubber diode of the second snubber circuit being connected to a second end of the secondary winding of the second transformer.

7. The switching power supply according to claim 5, wherein the primary winding of each transformer comprises two interleaved, parallel connected segments, each segment being connected in series with a power switch.

8. The switching power supply according to claim 7, wherein the second electrode of the snubber capacitor of the first snubber circuit is connected to the second electrode of the output capacitor via a first inductor and the second electrode of the snubber capacitor of the second snubber circuit is connected to the first electrode of the output capacitor via a second inductor.

10. The switching power supply according to claim 8, wherein the first and second inductors have a common core.

9. In a snubber circuit having a snubber capacitor and at least one snubber diode for a switching power supply having an output capacitor and providing a DC output;

the improvement comprising the snubber diode and the snubber capacitor being connected in series, in operation the snubber circuit transferring energy stored in the snubber capacitor to the output capacitor of the switching power supply, further comprising a second and a third snubber diode, a first electrode of the second snubber diode and a first electrode of the third snubber diode being connected to a joint electrode of the first snubber diode and the snubber capacitor, a second electrode of the second snubber diode being connectable to a first end of a secondary winding of the power supply, and a second electrode of the third snubber diode being connectable to a second end of the secondary winding of the power supply.