High impedance air core reactor

Abstract

Air core reactor includes a coil connected between first and second terminals. The coil is made of a succession of bundles of conductor (B1, B2, B3, . . . , BN) connected in series along an axis between the first terminal and the second terminal. Each bundle is made of one wire wound around the axis to form a multi-layer winding having a cross-section of N winding layers in a direction perpendicular to the axis, from a winding layer of rank 1 which is the closest to the axis to a winding layer of rank N which is the furthest from the axis. Each perpendicular winding layer includes several winding layers in the direction of the axis. The number of axial winding of the perpendicular winding layer of rank j (j=2, . . . , N) is equal or less than the number of axial winding layers of the perpendicular winding layer of rank j1.

Claims

1. An air core reactor comprising a coil connected between a first terminal and a second terminal, the coil being made of at least two bundles of conductor connected in series along an axis between the first terminal and the second terminal, each bundle of conductor being made of a wire wound around said axis so as to form a multi-layer winding having a cross-section made of N winding layers in a direction perpendicular to the axis, from a winding layer of rank 1 which is the closest to the axis to a winding layer of rank N which is the furthest from the axis, for each bundle of conductor, each winding layer in the direction perpendicular to the axis comprising several windings in the direction of the axis, the number of windings in the direction of the axis of the winding layer of rank j in the direction perpendicular to the axis, j being taken between 2 to N, being equal or less than the number of windings in the direction of the axis of the winding layer of rank j1 in the direction perpendicular to the axis, wherein all the bundles of conductor are made with a same wire in such a way that the air core reactor comprises only one wire, and wherein, for all the bundles of conductor of the air core reactor, the link between adjoining bundles of conductor being made by said same wire passing from the winding layer of rank N of a bundle of conductor to the winding layer of rank 1 of the adjoining bundle of conductor.

2. The air core reactor according to claim 1, wherein a cross section of each bundle of conductor is in a trapezoidal form.

3. The air core reactor according to claim 1, wherein a cross section of each bundle of conductor is in a rectangular form.

4. The air core reactor according to claim 1, wherein a cross section of each bundle of conductor is in a square form.

5. The air core reactor according to claim 1, wherein a cross section of each bundle of conductor is in a triangular form.

6. The air core reactor according to claim 1, wherein the wire conductor is encapsulated in an encapsulation pack made of fiberglass.

7. Process of manufacturing an air core reactor comprising a coil connected between a first terminal and a second terminal, characterized in that it comprises at least two steps of winding continuously a same wire around an axis, each step of winding said wire forming a multi-layer winding having a cross-section made of N winding layers in a direction perpendicular to the axis, from a winding layer of rank 1 which is the closest to the axis to a winding layer of rank N which is the furthest from the axis, for each bundle of conductor, each winding layer in the direction perpendicular to the axis comprising several windings in the direction of the axis, the number of windings in the direction of the axis of the winding layer of rank j in the direction perpendicular to the axis, j being taken between 2 to N, being equal or less than the number of windings in the direction of the axis of the winding layer of rank j1 in the direction perpendicular to the axis, wherein, for all the bundles of conductor, said process further comprising linking adjoining bundles of conductor by passing said same wire from the winding layer of rank N of a bundle of conductor to the winding layer of rank 1 of the adjoining bundle of conductor in such a way that the air core reactor comprises only one wire.

8. An air core reactor comprising a coil connected between a first terminal and a second terminal, the coil being made of at least two bundles of conductor connected in series along an axis between the first terminal and the second terminal, each bundle of conductor being made of a wire wound around said axis so as to form a succession of N concentric winding layers around the axis, from a winding layer of rank 1 which is the closest to the axis to a winding layer of rank N which is the furthest from the axis, two successive winding layers being connected in series, for each bundle of conductor, each winding layer in the direction perpendicular to the axis comprising several windings in the direction of the axis, the number of windings in the direction of the axis of the winding layer of rank j in the direction perpendicular to the axis, j being taken between 2 to N, being equal or less than the number of windings in the direction of the axis of the winding layer of rank j1 in the direction perpendicular to the axis, wherein all the bundles of conductor of the air core reactor are made with a same wire in such a way that the air core reactor comprises only one wire, wherein, for all the bundles of conductor, the link between two adjoining bundles of conductor being made by said same wire passing from the winding layer of rank N of a bundle of conductor to the winding layer of rank 1 of the adjoining bundle of conductor.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other characteristics and advantages of the invention will become clearer upon reading a preferred embodiment of the invention made in reference to the attached figures among which:

(2) FIGS. 1A and 1B show an example of an air core reactor according to the prior art;

(3) FIGS. 2A, 2B and 2C show an example of a first embodiment of an air core reactor according to the invention;

(4) FIG. 3 shows an example of the way a wire conductor is wound to form an air core reactor according to the first embodiment of the invention;

(5) FIG. 4 shows a first example of cross-section of an air core reactor of the invention;

(6) FIG. 5 shows a second example of cross-section of an air core reactor of the invention;

(7) FIG. 6 shows a third example of cross-section of an air core reactor of the invention;

(8) FIGS. 7-9 show examples of side view of bundles of conductor according to the invention.

(9) In all the figures, the same references designate the same elements.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

(10) FIG. 2A shows an overall view of an example of air core reactor according to the invention while FIGS. 2B and 2C show two detailed views of FIG. 2A.

(11) The air core of the invention comprises two cross-arms A1, A2, and a coil C2 made of a wire conductor W encapsulated in a fiberglass encapsulation E (see FIGS. 2A and 2B).

(12) According to the first embodiment of the invention, the winding system of the air core reactor uses only one round wire W as conductor. The turns of the round wire conductor W are accumulated to form several bundles of conductor B1, B2, B3, . . . , BN.

(13) The FIG. 3 illustrates an example of the way the wire conductor is wound to form two successive bundles Bi, Bj. The first bundle Bi is made by winding the wire eleven times around an axis so as to form a first layer of conductor in the direction of the axis, then by winding the wire ten times around the axis upon the first layer so as to form a second layer of conductor, and so on until a fifth layer of conductor made by winding the wire seven times around the axis upon a fourth layer. When the first bundle has been achieved, the second bundle Bj is made in the same way than the first bundle Bi from a first layer to a fifth layer. As an example, each bundle has a trapezoidal cross-section (see FIG. 4). However, other forms of cross-section are concerned by the invention as, for example, a rectangular form (see FIG. 5) or a triangular form (see FIG. 6).

(14) More generally, as it can be seen on FIG. 3, the wire conductor is wound on different levels to form a first bundle of conductor from a bottom level to an upper level and, when the upper level of the first bundle is reached, the wire conductor is taken back to the bottom level to form a second bundle of conductor next to the first bundle, and so on. A first terminal of the wire conductor is connected to one of the two cross-arms while the other terminal of the wire conductor is connected to the second cross-arm.

(15) According to a second embodiment of the invention, each bundle of conductor is made separately and the different bundles are series-connected afterwards by means of electrical connections. The FIGS. 7-9 show side views of elementary bundles of conductor made separately. The FIG. 7 corresponds to a rectangular cross-section. The FIG. 8 corresponds to a trapezoidal cross section. The FIG. 9 corresponds to a triangular cross section.

(16) Whatever is the embodiment, the air core reactor of the invention joins the benefits of air-core reactor technology with a very significant reduction in dimensions in comparison with the prior art. For example, a 800/15 A reactor can be built with very reduced weight and an external diameter of 1.28 m, which is far lower than the typical dimensions of air-core reactors of the prior art.

(17) The table below shows the comparison among three solutions: (1) prior art iron core oil-filled reactor, (2) prior art air core reactor, (3) air core reactor according to the invention.

(18) TABLE-US-00001 Reactor DIMENSIONS (m) Weight (kg) (1) Iron-core oil-filled reactor 2.88 (W) 3.20 (H) 7200 (2) Prior art air-core reactor 3.00 (D) 2.93 (H) 609 (3) Air core reactor of the 1.28 (D) 2.00 (H) 381 invention

(19) With W for Width, H for Height and D for Diameter.

(20) More generally, the air core reactor of the invention presents better characteristics in all points, when compared to all other available present solutions in the market.

(21) A main advantage of the invention is to provide a high impedance air core reactor. It is therefore possible to achieve very high impedance air core reactors (as high as 10 k for example), thus replacing oil-filled reactors with all benefits of the air core reactor technology, i.e. much lower cost, weight and dimensions, leakage and maintenance free, robustness and simplicity of mounting and installation.