Three-phase air-core reactor

Abstract

The present invention relates to a three-phase air-core reactor comprising three identically structured single-phase inductor units; each single-phase inductor unit comprises an air-core coil, a first magnetic shielding structure wound circumferentially around the air-core coil, and a pair of second magnetic shielding structures symmetrically arranged on either side of the air-core coil and opposite the center of the air-core coil; the first magnetic shielding structure is provided with at least one opening; and the second magnetic shielding structure comprises a plurality of magnetic shielding blocks radially spaced from the center of the air-core coil outward. This invention optimizes the overall performance of the three-phase air-core reactor.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer reactors for electric locomotives and rolling stock, and in particular to a three-phase air-core reactor. Background Art

[0002] The reactor relies on magnetic flux leakage in the air to store energy. When the IGBT is turned off, the reactor releases energy. When the IGBT is turned on, the reactor is magnetized and stores energy, thereby smoothing the square wave current of the switching power supply into a continuous current, reducing the system current impact, and achieving system vibration reduction and noise reduction.

[0003] Typically, three-phase reactors use an iron-core design, which adds an air gap in the core to increase magnetic leakage and achieve energy storage and continuous current flow. However, iron-core reactors have the following disadvantages compared to air-core reactors: First, they have low energy storage capacity, low magnetic resistance, and a short time constant (τ) for charging and discharging magnetic energy. This results in a low current smoothing capability and a high rate of change (di / dt) of system current. The electrodynamic forces generated by high-frequency current fluctuations throughout the system circuit can cause severe mechanical vibration, generating noise.

[0004] Secondly, its own iron core becomes a single-frequency pure sound source when it is repeatedly charged and discharged, and the electromagnetic noise of the entire system exceeds the standard and is sharp and harsh.

[0005] The air-core reactor can completely solve the shortcomings of the iron-core reactor and is very effective in suppressing the noise of the traction system. However, it has the following disadvantages: the magnetic circuit is not bound by the iron core, and the leakage magnetic flux chooses the path with the smallest magnetic resistance in the air to form a closed loop. Therefore, the leakage magnetic flux will penetrate the surrounding equipment with higher magnetic permeability, causing uncontrolled changes in inductance; the leakage magnetic flux is far away, which can easily cause magnetic field radiation to passengers in the car and interfere with the ground signal system. The surrounding equipment will heat up in the high-frequency magnetic field, and in severe cases it will burn out or even catch fire; if it is made into a three-phase air-core inductor, the magnetic circuits in the three-phase coils may be entangled and linked with each other, resulting in serious mutual inductance, which will cause mutual interference between the phases of the power supply when the converter is working. Summary of the Invention

[0006] The purpose of the present invention is to provide a three-phase air-core reactor to solve the technical problem of optimizing the performance of the three-phase air-core reactor.

[0007] The three-phase air-core reactor of the present invention is implemented as follows: a three-phase air-core reactor, comprising: three single-phase inductance units with the same structure; each single-phase inductance unit comprises a hollow coil, a first magnetic shielding structure wound around the circumferential outside of the hollow coil, and a pair of second magnetic shielding structures symmetrically arranged on both sides of the hollow coil and opposite to the center of the hollow coil; wherein the first magnetic shielding structure is provided with at least one opening; and the second magnetic shielding structure comprises a plurality of magnetic shielding blocks radially spaced apart from the center of the hollow coil to the circumferential outside.

[0008] In an optional embodiment of the present invention, the three single-phase inductor units are arranged in an I-shape so that every two adjacent single-phase inductor units are vertically distributed.

[0009] In an optional embodiment of the present invention, the three single-phase inductor units are arranged in a cross shape so that every two adjacent single-phase inductor units are vertically distributed.

[0010] In an optional embodiment of the present invention, the three single-phase inductor units are integrated into an integral component via a fixing plate.

[0011] In an optional embodiment of the present invention, the axial cross-section of the hollow coil is a rectangular structure; the four end corners of the rectangular structure are arc transitions; and the cross-section of the center of the hollow coil is a rectangular structure.

[0012] In an optional embodiment of the present invention, the multiple magnetic shielding blocks located on the same side of the hollow coil include four corner magnetic shielding blocks with the same structure at the four corners of the center of the hollow coil with a rectangular structure, and three side magnetic shielding blocks with the same structure arranged at intervals along the two long sides of the center of the hollow coil with a rectangular structure.

[0013] In an optional embodiment of the present invention, the size of the corner magnetic shielding block is larger than the size of the side magnetic shielding block.

[0014] In an optional embodiment of the present invention, there is a gap between the first magnetic shielding structure and the circumferential outer side of the hollow coil; and there is a gap between a pair of the second magnetic shielding structures and both side end surfaces of the hollow coil.

[0015] In an optional embodiment of the present invention, the first magnetic shielding structure is wound around the circumferential outside of the air-core coil through a first supporting member.

[0016] In an optional embodiment of the present invention, the plurality of magnetic shielding blocks located on the same side of the hollow coil are formed into a block structure by epoxy resin casting or vacuum dipping; and the block structure is connected to the hollow coil via a second supporting member.

[0017] Compared to the prior art, the embodiments of the present invention have the following beneficial effects: The three-phase air-core reactor of the present invention, wherein the single-phase inductance unit used therein, includes an air-core coil and a first magnetic shielding structure and a second magnetic shielding structure. The air-core coil can increase the magnetic resistance, thereby increasing the time constant τ of the reactor's charge and discharge energy, enhancing the smoothing effect, making the current waveform of the system circuit of each phase inductance unit smoother, and reducing the system noise. The combination of the first magnetic shielding structure and the second magnetic shielding structure can reduce the magnetic field radiation range of the traditional air-core reactor, effectively reducing the interference of the reactor on the track signal, avoiding eddy current heating of the reactor's leakage magnetic flux on the surrounding equipment, and making the three-phase magnetic flux independent of each other, not interlinking, and reducing the mutual inductance effect between phases. Compared with the traditional shell-type reactor in the prior art that is only shielded on four sides, the three-phase air-core reactor structure of the present invention can achieve leakage magnetic shielding on six sides, with lower leakage magnetic radiation and no need to consider the leakage magnetic surface during installation. When the three-phase air-core reactor of the present invention is used in rail transit rapid transit vehicles, it is not restricted in its under-vehicle placement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and examples.

[0019] Figure 1 A schematic structural diagram of a single-phase inductor unit of a three-phase air-core reactor provided by an embodiment of the present invention from a first perspective is shown;

[0020] Figure 2 A schematic structural diagram of a single-phase inductor unit of a three-phase air-core reactor provided by an embodiment of the present invention from a second perspective is shown;

[0021] Figure 3 A schematic structural diagram of a single-phase inductor unit of a three-phase air-core reactor provided in an embodiment of the present invention in an optional implementation scenario is shown;

[0022] Figure 4 A schematic diagram showing a three-phase air-core reactor in an I-shaped structure from a first perspective according to an embodiment of the present invention is shown;

[0023] Figure 5 A schematic diagram from a second perspective showing an I-shaped structure of a three-phase air-core reactor provided by an embodiment of the present invention is shown;

[0024] Figure 6 A schematic diagram showing a three-phase air-core reactor in a cross-shaped structure from a first perspective is shown in an embodiment of the present invention;

[0025] Figure 7 A second perspective schematic diagram of a three-phase air-core reactor provided by an embodiment of the present invention in a cross-shaped structure is shown.

[0026] In the figure: an air-core coil 1 , a first magnetic shielding structure 2 , an opening 21 , a corner magnetic shielding block 31 , a side magnetic shielding block 32 , a first supporting member 4 , a second supporting member 5 , and a block structure 6 . DETAILED DESCRIPTION

[0027] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0028] Reference Figures 1 to 7 As shown, this embodiment provides a three-phase air-core reactor suitable for use in three-phase AC powered rapid transit vehicles. Specifically, the three-phase air-core reactor of this embodiment includes: three single-phase inductor units of identical structure; each single-phase inductor unit includes an air-core coil 1, a first magnetic shielding structure 2 wound circumferentially outside the air-core coil 1, and a pair of second magnetic shielding structures symmetrically arranged on both sides of the air-core coil 1 and opposite to the center of the air-core coil 1; wherein the first magnetic shielding structure 2 is provided with at least one opening 21; and the second magnetic shielding structure includes a plurality of magnetic shielding blocks radially spaced apart from the center of the air-core coil 1. The drawings of this embodiment only take the case where two symmetrically distributed openings 21 are provided on the first magnetic shielding structure 2 as an example.

[0029] This embodiment can avoid the problem of the iron core being closed to form a single-turn circuit, forming a transformer effect, and causing circuit short-circuit failure by providing at least one opening 21 on the first magnetic shielding structure 2 .

[0030] The second magnetic shielding structure includes multiple magnetic shielding blocks that are radially designed from the center of the hollow coil 1 to the circumference outward, so that the three-phase hollow reactor of this embodiment can form natural convection with the ambient air; it can be designed to be cooled by vehicle running air without forced cooling.

[0031] In one optional implementation, the three single-phase inductance units are arranged in an I-shape, with each adjacent pair of single-phase inductance units arranged vertically. In another optional implementation, the three single-phase inductance units are arranged in a X-shape, with each adjacent pair of single-phase inductance units arranged vertically. This vertical arrangement of each pair of adjacent single-phase inductance units allows the air-core coils 1 of each pair of adjacent single-phase inductance units to be arranged vertically, thereby controlling the mutual inductance coefficient between the three-phase air-core reactors to 0.2%, meeting the inter-phase mutual inductance requirements of the traction system of rail transit rapid transit vehicles.

[0032] The I-shaped or X-shaped arrangement reduces the magnetic circuit hinge between the coils, minimizing the mutual inductance between phases and preventing single-phase harmonics from propagating to other phases through mutual inductance. Compared to conjugated core-type or shell-type three-phase reactors, this structure, combined with magnetic shielding, can reduce the mutual inductance between phases by an order of magnitude. Actual testing has found that the mutual inductance of conjugated core-type or shell-type three-phase reactors can only be less than 50μT, while the mutual inductance of the three-phase air-core reactor using this embodiment is less than 5μT.

[0033] It should be noted that the three single-phase inductance units can be integrated into an integral component in an "I" shape or a "X" shape through a fixing plate to form a three-phase air-core reactor; or each single-phase inductance unit can be separately provided with an outer shell to form an independent integral component. In the specific use process, the three independent single-phase inductance units are arranged into an "I" shape or a "X" shape structure. The above two usage scenarios can both meet the use requirements of this embodiment, and this embodiment does not make an absolute limitation on this. When the vehicle model is small, the idle space under the vehicle can be effectively utilized, and the single-phase inductance unit can be installed as an independent individual in a dispersed manner. If space permits, the three single-phase inductance units can be installed as a whole. Therefore, the above two scenarios are suitable for the needs of different under-vehicle designs.

[0034] It should be noted that the hollow coil 1 of this embodiment has a rectangular axial cross-section; the four corners of this rectangular structure are arc-shaped transitions; and the center cross-section of the hollow coil 1 also has a rectangular structure. This rectangular axial cross-section of the hollow coil 1 improves the space filling rate of the hollow coil 1, effectively utilizes the space under the vehicle, and reduces the overall volume and installation space of the three-phase air-core reactor.

[0035] Based on the above structure, the multiple magnetic shielding blocks located on the same side of the air-core coil 1 include four identical corner magnetic shielding blocks 31, each corresponding to the four corners of the center of the rectangular air-core coil 1, and three identical side magnetic shielding blocks 32, each corresponding to the two long edges of the center of the rectangular air-core coil 1. In a preferred embodiment, the corner magnetic shielding blocks 31 are larger than the side magnetic shielding blocks 32 to prevent magnetic saturation.

[0036] Furthermore, for the three-phase air-core reactor of this embodiment, it is necessary to explain that there is a gap between the first magnetic shielding structure 2 and the circumferential outer side of the air-core coil 1; and there is a gap between a pair of second magnetic shielding structures and the two side end faces of the air-core coil 1.

[0037] Based on the above structure, optionally, the first magnetic shielding structure 2 is wound around the circumferential outside of the hollow coil 1 via a first support member 4. For the second magnetic shielding structure, multiple magnetic shielding blocks located on the same side of the hollow coil 1 are formed into a block structure 6 by epoxy resin casting or vacuum dipping; and the block structure 6 is connected to the hollow coil 1 via a second support member 5.

[0038] In summary, for the three-phase air-core reactor of this embodiment, the single-phase inductance unit used therein includes an air-core coil 1, a first magnetic shielding structure 2, and a second magnetic shielding structure. The air-core coil 1 can increase the magnetic resistance, increase the time constant τ of the charge and discharge energy of the reactor, enhance the smoothing effect, make the current waveform of the system circuit of each phase inductance unit smoother, and reduce the system noise. The combination of the first magnetic shielding structure 2 and the second magnetic shielding structure can reduce the magnetic field radiation range of the traditional air-core reactor, effectively reduce the interference of the reactor on the track signal, avoid the eddy current heating of the reactor leakage flux on the surrounding equipment, and make the three-phase magnetic flux independent of each other, not cross-linked, and reduce the mutual inductance effect between phases. Compared with the traditional shell-type reactor with only four-sided shielding in the prior art, the three-phase air-core reactor structure of the present invention can achieve leakage magnetic shielding on six sides, with lower leakage magnetic radiation and no need to consider the leakage magnetic surface during installation. When the three-phase air-core reactor of this embodiment is used in rail transit rapid transit vehicles, the under-vehicle arrangement is not restricted. In addition, since the three-phase air-core reactor of this embodiment has no iron core, the self-noise of the reactor without iron core is reduced by 20dB compared with the reactor with iron core when the system is working, and the traction motor noise is reduced by 10dB.

[0039] The above specific embodiments further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0041] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0042] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0044] In the present invention, unless otherwise expressly specified or limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A three-phase air-core reactor, characterized in that: include: Three single-phase inductor units with identical structures; each single-phase inductor unit includes an air-core coil, a first magnetic shielding structure wound around the circumference of the air-core coil, and a pair of second magnetic shielding structures symmetrically arranged on both sides of the air-core coil and opposite to the center of the air-core coil; The first magnetic shielding structure is provided with at least one opening; and the second magnetic shielding structure comprises a plurality of magnetic shielding blocks radially spaced from the center of the hollow coil to the circumference outside; The three single-phase inductance units are arranged in an "I" shape so that every two adjacent single-phase inductance units are vertically distributed; The axial cross-section of the hollow coil is a rectangular structure; the four end corners of the rectangular structure are arc transitions; and the cross-section of the center of the hollow coil is a rectangular structure; The multiple magnetic shielding blocks located on the same side of the hollow coil include four corner magnetic shielding blocks with the same structure at the four corners of the center of the rectangular hollow coil, and three side magnetic shielding blocks with the same structure arranged at intervals along the two long sides of the center of the rectangular hollow coil. The size of the corner magnetic shielding block is greater than that of the side magnetic shielding block; The three single-phase inductor units are integrated into an integral component via a fixing plate; There is a gap between the first magnetic shielding structure and the circumferential outer side of the air-core coil; and there is a gap between each of the pair of second magnetic shielding structures and two side end surfaces of the air-core coil.

2. The three-phase air-core reactor according to claim 1, characterized in that: The first magnetic shielding structure is wound around the circumferential outer side of the air-core coil through the first supporting member.

3. The three-phase air-core reactor according to claim 1, characterized in that: A plurality of magnetic shielding blocks located on the same side of the air-core coil are formed into a block structure by epoxy resin casting or vacuum dipping; and the block structure is connected to the air-core coil via a second supporting member.

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