Resonant converter

• US 6,956,755 B2
• Filed: 09/18/2001
• Issued: 10/18/2005
• Est. Priority Date: 10/13/2000
• Status: Expired due to Term

• Current Assignee: American Power Conversion Denmark Aps (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Nielsen, Henning Roar
• Primary Examiner(s): Laxton, Gary L.
• Application Number:
  US10/399,014
• Publication Number:
  US 20040052099A1
• Time in Patent Office: 1,491 Days
• Field of Search: 363/17, 363/21.02, 363/21.03, 363/40, 363/95, 363/97, 363/98, 363/131, 363/132, 363/135, 363/136, 323/224, 323/225, 323/282
• US Class Current: 363/132
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• 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
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

The invention relates to a resonant converter (200, 300). The resonant converter (200, 300) consists of a first circuit, primarily a DC circuit (201, 301) connected to a resonant circuit (207, 307) which is further connected to a switch/filter circuit (212, 312) which is connected to a second circuit, primarily an AC circuit (219, 319). The proposed resonant converter (200, 300) is unique in that the resonant converter (200, 300) contains a direct connection between a voltage center (203, 303) in the DC circuit (201, 301) and a voltage center (209, 309, 325) in the resonant circuit (207, 307), and that the resonant circuit (207, 307) contains at least one transformer having at least two windings (223, 224, 331, 332, 333, 334), wherein there is a connection from the windings (223, 224, 331, 332) of the transformer to at least first and second switches (215, 216, 315, 316, 328, 329), wherein activation of the switches (215, 216, 315, 316, 328, 329) forms a connection to at least a first node (214, 314, 327), wherein a voltage center (203, 303) in the DC circuit (201, 301) is also connected to the first node (214, 314, 327) by activation of at least a third switch (213, 313, 326). This results in a resonant converter (200, 300) wherein there are just switches (213, 215, 216, 313, 315, 316, 326, 328, 329) in the switch/filter circuit (212, 312) so that the number of switches (213, 215, 216, 313, 315, 316, 326, 328, 329) with power loss is as low as possible. The resonant converter (200, 300) moreover has the advantage that there is a direct connection from the center (203, 303) of the DC circuit (201, 301) to the load (219, 319), without this current path running through the coil (217, 317, 330) to the resonant circuit (207, 307). This minimizes the current load of the coil (217, 317, 330) and hereby the influence on the frequency of the resonant converter in case of a short-circuit on the output of the resonant converter (200, 300) where a great output current is to be provided, while the output voltage is close to zero volt. The reason is that a switch (213, 313, 326) in the switch/filter circuit (212, 312), which is connected to a voltage center (214, 314, 327), will conduct for by far the greatest part of the time at an output voltage close to zero volt, and that this current path bypasses the resonant circuit (207, 307). In addition, reduced switching across the switches (213, 215, 216, 313, 315, 316, 326, 328, 329) is achieved.

Claims

1. A resonant converter for coupling between a DC circuit and an AC circuit comprising:

a resonant circuit having an input to couple to the DC circuit and being coupled to a switch/filter circuit, having an output to couple to the AC circuit, wherein the resonant converter contains a direct connection between a first voltage center in the DC circuit and a second voltage center in the resonant circuit, and wherein the resonant circuit comprises at least one transformer having at least two windings, wherein there is a connection from the at least two windings of the transformer to at least first and second switches, wherein activation of the first and second switches respectively couples the at least two windings to at least a first node, and wherein the first voltage center in the DC circuit is also coupled to the first node by activation of at least a third switch.

2. A resonant converter according to claim 1, wherein the transformer has additional windings which operate in anti-phase to the at least two windings.

3. A resonant converter according to claim 1, wherein the resonant converter is used as a DC to AC converter.

4. A resonant converter according to claim 1, wherein the resonant converter is used as an AC to DC converter, wherein the first node of the resonant converter is coupled to the output of the switch/filter circuit, wherein the first node is coupled by activation of the switches to the at least two windings on the transformer, and wherein the at least two windings are coupled to the DC circuit.

5. A resonant converter according to claim 1, wherein the resonant converter is incorporated in an N-phase system having at least one resonant converter per phase, the number of phases N being at least 1.

6. A resonant converter according to claim 5, wherein the resonant circuit and the DC circuit are commonly coupled to several switch/filter circuits in the N-phase system, wherein each phase is formed by activation of independent sets of switches.

7. A resonant converter according to claim 1, wherein the resonant converter is used as an AC to AC converter.

8. A resonant converter according to claim 7, wherein the resonant converter is adapted to convert at least one of a group of parameters including frequency, voltage and current.

9. A resonant converter according to claim 1, wherein the first, second and third switches are semiconductor devices selected from a group consisting of field effect transistors, bipolar transistors, Insulated Gate Bipolar Transistors (IGBT), Gate Turn-Off thyristors (GTO) and Injection Enhanced Gate Transistors (IEGT).

10. A resonant converter according to claim 1, wherein the resonant converter uses three point frequency modulation.

11. A resonant converter according to claim 1, wherein a resonance of the resonant circuit is controlled by at least one of the first, second and third switches in the switch/filter circuit.

12. A resonant converter according to claim 1, wherein a resonance of the resonant circuit is controlled by a current source which is coupled magnetically to the resonant circuit via a core of the transformer.

13. An N-phase resonant converter comprising:

a first input, a second input and a third input to couple to a DC circuit;

a resonant circuit including a transformer having a first winding and a second winding, a first capacitor electrically coupled between the first winding and a first node and a second capacitor that is coupled between the second winding and the first node;

a second node to couple to an AC circuit; and

a first switch circuit including a first switch coupled in series between the first node and the second node;

a second switch coupled between the first winding and the second node; and

a third switch coupled between the second winding and the second node;

wherein N is at least one;

wherein activation of the second switch creates an electrical coupling between the first winding and the second node and activation of the third switch creates an electrical coupling between the second winding and the second node; and

wherein activation of the first switch creates an electrical coupling between the first node and the third input.

14. The N-phase resonant converter according to claim 13, wherein the first and second windings are magnetically coupled via a core.

15. The N-phase resonant converter according to claim 13, further comprising a first filter circuit electrically coupled between the second node and the AC circuit.

16. The N-phase resonant converter according to claim 15, wherein N is at least 3, and further comprising:

a second switch circuit comprising a fourth switch coupled between the first winding and a third node; and

a fifth switch coupled between the second winding and the third node;

a fourth input to couple to a second AC circuit, the fourth input being coupled to the third node;

a third switch circuit comprising a sixth switch coupled between the first winding and a fourth node; and

a seventh switch coupled between the second winding and the fourth node; and

a fifth input to couple to a third AC circuit, the fifth input being coupled to the fourth node;

wherein activation of the fourth switch creates an electrical coupling between the first winding and the third node, and wherein activation of the fifth switch creates an electrical coupling between the second winding and the third node; and

wherein activation of the sixth switch creates an electrical coupling between the first winding and the fourth node, and wherein activation of the seventh switch creates an electrical coupling between the second winding and the fourth node.

17. The N-phase resonant converter according to claim 16, further comprising:

a second filter circuit electrically coupled between the third node and the fourth input; and

a third filter circuit electrically coupled between the fourth node and the fifth input.

18. The N-phase resonant converter according to claim 16, wherein the second switch circuit further comprises an eighth switch coupled between ground and the third node;

and wherein the third switch circuit further comprises a ninth switch coupled between ground and the fourth node.

19. A double resonant converter to couple between a DC circuit and an AC circuit, comprising:

a transformer having first, second, third and fourth windings, a first terminal of the DC circuit being coupled at a centerpoint between the first and second windings and a second terminal of the DC circuit being coupled to a centerpoint between the third and fourth windings;

a first switch circuit that couples the first and third windings to a first node; and

a second switch circuit that couples the second and fourth windings to the first node;

wherein the AC circuit is coupled to the first node;

wherein activation of the first switch circuit forms an electrical coupling between the first and third windings and the first node and activation of the second switch circuit forms an electrical coupling between the second and fourth windings and the first node; and

wherein the first and second windings of the transformer are adapted to operate in antiphase with the third and fourth windings.

20. A method of coupling an AC circuit to a DC circuit using a resonant converter, the resonant converter having a DC input to couple to the DC circuit, an AC output to couple to the AC circuit, a transformer having a first winding coupled between the DC input and a first node of the resonant converter and a second winding coupled between the DC input and a second node of the resonant converter, the method comprising:

applying a DC voltage to the DC input; and

selectively coupling the first node to the AC output, the second node to the AC output and selectively coupling the AC output to a third node to generate an AC voltage at the AC output.