DC converters

• US 20040037100A1
• Filed: 08/26/2002
• Published: 02/26/2004
• Est. Priority Date: 08/26/2002
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Potentia Semiconductor, Inc.
• Inventors: Orr, Raymond K., Liu, Yan-Fei
• Granted Patent: US 6,771,518 B2
• Time in Patent Office: Days
• US Class Current: 363/131
• CPC Class Codes: H02M 3/005 using Cuk converters
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer

Abstract

In a DC converter, a transformer has a first winding coupled in series with a first capacitor and a first switch between a first pair of terminals, and a second winding coupled in series with a second capacitor and an inductor between a second pair of terminals. A second switch is coupled in parallel with the series-connected first winding and first capacitor. A third switch or diode is coupled in parallel with the series-connected second winding and second capacitor. The capacitors provide energy transfer in either direction via the transformer. Leakage inductance of the transformer facilitates zero voltage switching conditions, and the transformer core is reset in each cycle by charge balancing between the capacitors. The switches can comprise AC switches. The transformer can be an autotransformer.

Claims

1. A DC converter comprising a buck or boost regulator coupled between input terminals for a supply voltage and output terminals for a regulated output of the converter, the regulator including at least a first switch which is controllable for regulating said output, and a transformer, wherein the regulator comprises an input circuit coupled to the input terminals and having a first capacitor connected in series with a primary winding of the transformer, and an output circuit coupled to the output terminals and having a second capacitor connected in series with a secondary winding of the transformer, and wherein successive cycles of operation of the converter each comprise a phase of energy transfer via the transformer from the first capacitor to the second capacitor during a first state of said switch, and a phase of charge balancing between the capacitors during a second state of said switch.

2. A converter as claimed in claim 1 wherein said first switch is connected in series with the first capacitor and primary winding between the input terminals, and the input circuit further comprises a second switch in parallel with the series-connected first capacitor and primary winding, the second switch being controlled in a complementary manner to the first switch.

3. A converter as claimed in claim 1 wherein the input circuit comprises four switches connected to the input terminals in a full bridge arrangement, the series-connected first capacitor and primary winding being connected in a diagonal of the bridge.

4. A converter as claimed in claim 1 wherein the input circuit comprises two switches connected in series, and two capacitors connected in series, between the input terminals, the primary winding being connected between a junction between the two switches and a junction between said two capacitors, said two capacitors constituting said first capacitor connected in series with the primary winding.

5. A converter as claimed in claim 1 wherein the output circuit comprises an inductor connected in series with the second capacitor and secondary winding between the output terminals, a diode or switch in parallel with the series-connected second capacitor and secondary winding, and a capacitor coupled between the output terminals.

6. A converter as claimed in claim 2 wherein the output circuit comprises an inductor connected in series with the second capacitor and secondary winding between the output terminals, a diode or switch in parallel with the series-connected second capacitor and secondary winding, and a capacitor coupled between the output terminals.

7. A converter as claimed in claim 3 wherein the output circuit comprises an inductor connected in series with the second capacitor and secondary winding between the output terminals, a diode or switch in parallel with the series-connected second capacitor and secondary winding, and a capacitor coupled between the output terminals.

8. A converter as claimed in claim 4 wherein the output circuit comprises an inductor connected in series with the second capacitor and secondary winding between the output terminals, a diode or switch in parallel with the series-connected second capacitor and secondary winding, and a capacitor coupled between the output terminals.

9. A converter as claimed in claim 1 wherein the transformer primary and secondary windings are electrically isolated from one another.

10. A converter as claimed in claim 1 wherein the transformer comprises an autotransformer.

11. A DC converter comprising:

a transformer having first and second windings;

first, second, and third controllable switches;

first, second, and third capacitors; and

an inductor;

wherein the first winding, first capacitor, and first switch are coupled in series between a first pair of terminals;

the second switch is coupled in parallel with the series-connected first winding and first capacitor;

the second winding, second capacitor, and inductor are coupled in series between a second pair of terminals;

the third switch is coupled in parallel with the series-connected second winding and second capacitor; and

the third capacitor is coupled between one of the first and second pairs of terminals.

12. A converter as claimed in claim 11 and including a fourth capacitor coupled between the other of the first and second pairs of terminals.

13. A converter as claimed in claim 12 wherein the first capacitor is constituted by two capacitors each connected between the first winding and a respective terminal of the first pair of terminals.

14. A converter as claimed in claim 11 and including two further controllable switches via which the first winding is connected to respective terminals of the first pair of terminals.

15. A DC converter as claimed in claim 11 wherein each controllable switch comprises a semiconductor switch having a reverse parallel diode.

16. A converter as claimed in claim 11 wherein the transformer windings are electrically isolated from one another.

17. A converter as claimed in claim 11 wherein the transformer comprises an autotransformer.

18. A DC converter comprising a transformer having a first winding coupled in series with a first capacitor and a first controllable switch between a first pair of terminals, and a second winding coupled in series with a second capacitor and an inductor between a second pair of terminals;

a second controllable switch coupled in parallel with the series-connected first winding and first capacitor;

a diode coupled in parallel with the series-connected second winding and second capacitor; and

a third capacitor coupled between one of the first and second pairs of terminals.

19. A converter as claimed in claim 18 and including a fourth capacitor coupled between the other of the first and second pairs of terminals.

20. A converter as claimed in claim 19 wherein the first capacitor is constituted by two capacitors each connected between the first winding and a respective terminal of the first pair of terminals.

21. A converter as claimed in claim 18 and including two further controllable switches via which the first winding is connected to respective terminals of the first pair of terminals.

22. A converter as claimed in claim 18 wherein each controllable switch comprises a semiconductor switch having a reverse parallel diode.

23. A converter as claimed in claim 22 wherein said diode coupled in parallel with the series-connected second winding and second capacitor is constituted by a reverse parallel diode of a further controllable semiconductor switch.

24. A converter as claimed in claim 18 wherein said diode coupled in parallel with the series-connected second winding and second capacitor is constituted by a reverse parallel diode of a further controllable semiconductor switch.

25. A converter comprising:

a first switch, a first capacitor, and a first winding of a transformer coupled in series between a first pair of terminals;

a second switch coupled in parallel with the series-connected first capacitor and first winding;

a second winding of the transformer, a second capacitor, and an inductor coupled in series between a second pair of terminals;

a unidirectionally conductive device or a third switch coupled in parallel with the series-connected second winding and second capacitor;

a third capacitor coupled between the first or the second pair of terminals; and

a circuit for controlling the switches, the first and second switches being controlled so that they are not simultaneously conductive.

26. A converter as claimed in claim 25 wherein at least one of the switches comprises a bidirectional switch.

27. A converter as claimed in claim 25 wherein the transformer windings are electrically isolated from one another.

28. A converter as claimed in claim 25 wherein the transformer comprises an autotransformer.