Feed cable for maglev train

Abstract

The utility model relates to the technical field of cables, in particular to a feed cable for a maglev train, which comprises a conductor. The outer wall of the conductor is coated with the semi-conductive wrapping layer; the insulating layer is extruded on the outer wall of the semi-conductive wrapping layer; the semi-conductive shielding layer is coated on the outer wall of the insulating layer; and the braided shielding layer is coated on the outer wall of the semi-conductive shielding layer. According to the utility model, the inner layer of the conductor is a circular stranded conductor, the outer layer is a fan-shaped stranded conductor, impedance rise caused by skin effect can be reduced, the insulating layer is a double-layer insulating layer, the inner layer adopts a high-density polyethylene structure, and the outer layer adopts a gradient foaming structure, so that the skin depth of high-frequency current can be effectively reduced, and the service life of the cable is prolonged. In addition, the low dielectric constant foaming layer also reduces the eddy current loss of the shielding layer, the overall thermal stability of the cable is improved, and higher current-carrying capacity can be realized.

Description

Technical Field

[0001] This utility model relates to the field of power cable technology, and more specifically to a power supply cable for maglev trains. Background Technology

[0002] The high-speed maglev railway system consists of four main parts: track, rolling stock, power supply, and operation control system. Cables, acting as the lifeblood of the power supply system, bear the crucial responsibility of providing the train with the necessary electrical energy. The high-voltage, high-current, and high-frequency operating environment of maglev trains places extremely high demands on cable performance, requiring characteristics such as high temperature resistance, interference resistance, and long lifespan. Feeder cables are primarily responsible for transmitting electrical energy from ground substations to the train's traction and levitation systems, driving long-stator linear motors to generate magnetic fields, enabling the train's levitation, guidance, and propulsion. Given the high-frequency, high-current power transmission involved in the maglev train's operating environment, the cables require high current-carrying capacity and strong electromagnetic interference resistance to prevent signal distortion or equipment malfunction.

[0003] Traditional power supply cables often employ a design with round stranded conductors and solid insulation layers. For example, the power supply cable and its manufacturing process for maglev trains proposed in publication CN112582100A, as well as existing waterproof power supply cables for maglev trains, use round stranded conductors, which result in a surge in AC resistance at high frequencies. Meanwhile, the solid insulation layer has high dielectric loss, which can easily cause the cable temperature to rise excessively, thus limiting the cable's maximum current carrying capacity. Summary of the Invention

[0004] To address the technical problems existing in existing power cables, this utility model proposes a feeder cable for maglev trains, comprising:

[0005] Conductor, said conductor comprising multilayer stranded conductor;

[0006] A semiconducting cladding layer is used to cover the outer wall of the conductor;

[0007] An insulating layer is extruded onto the outer wall of the semiconductive wrapping layer;

[0008] A semi-conductive shielding layer is wrapped around the outer wall of the insulating layer;

[0009] A braided shielding layer is wrapped around the outer wall of the semiconductive shielding layer;

[0010] A wrapping shielding layer is used to cover the outer wall of the braided shielding layer.

[0011] The outer sheath is extruded onto the outer wall of the wrapping shielding layer;

[0012] The multilayer stranded conductor includes an inner stranded conductor and an outer stranded conductor. The outer stranded conductor is a fan-shaped compacted stranded conductor. The insulation layer includes an inner insulation layer and an outer insulation layer. The inner insulation layer includes a high-density polyethylene insulation layer, and the outer insulation layer includes a gradient foamed insulation layer. The pore size of the gradient foamed insulation layer decreases sequentially from the inside to the outside of the cable.

[0013] Preferably, the porosity of the gradient foamed insulation layer is 40±5%.

[0014] Preferably, the pore size in the gradient foamed insulation layer is 10~50 micrometers.

[0015] Preferably, the gradient foamed insulation layer includes a macroporous thickness layer, a mesoporous thickness layer, and a microporous thickness layer, wherein the pore size in the macroporous thickness layer is 30-50 micrometers, the pore size in the mesoporous thickness layer is 20-40 micrometers, and the pore size in the microporous thickness layer is 10-30 micrometers.

[0016] Preferably, the thickness ratio of the inner insulating layer to the outer insulating layer is 1:3 to 1:4.

[0017] Preferably, the conductor includes a central circular stranded conductor and an outer fan-shaped stranded conductor. The circular stranded conductor includes a steel-core aluminum stranded wire structure, and the fan-shaped stranded conductor includes an aluminum stranded wire structure with a fan-shaped cross-section.

[0018] Preferably, the semiconductive cladding layer includes a semiconductive resistive water cladding layer.

[0019] Preferably, the semiconductive shielding layer includes a semiconductive nylon wrapping tape, with two wrapping layers.

[0020] Preferably, the braided shielding layer includes a copper wire loose-wound shielding layer, the copper wire being loosely wound in a left-hand direction; the wrapped shielding layer includes a copper strip wrapped shielding layer, the copper strip being wrapped in a right-hand direction; the diameter of the copper wire is 0.8 mm, the pitch of the copper wire is 352~432 mm, the thickness of the copper strip is 0.1 mm, and a layer of non-woven fabric is wrapped around the copper strip, the overlap rate of the non-woven fabric is not less than 15%, and the thickness of the wrapping tape is 0.2 mm.

[0021] Preferably, the outer sheath comprises a high-density polyethylene sheath.

[0022] Compared with the prior art, the significant advantages of the power supply cable for maglev trains of this invention are:

[0023] The power supply cable for maglev trains proposed in this invention features an inner layer of circular stranded conductors and an outer layer of fan-shaped stranded conductors, which reduces impedance rise caused by the skin effect. Simultaneously, the insulation layer is a double-layer design, with the inner layer using a high-density polyethylene structure and the outer layer using a gradient foaming structure. This effectively reduces the skin depth of high-frequency currents, and the gradient pores compensate for temperature-induced changes in dielectric constant, resulting in more stable impedance matching and enabling the cable to perform high-frequency transmission. Furthermore, the low-dielectric-constant foaming layer reduces eddy current losses in the shielding layer, improving the overall thermal stability of the cable and achieving higher current carrying capacity. Attached Figure Description

[0024] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the structure of the power supply cable for the magnetic levitation train shown in this utility model.

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of the power supply cable for the magnetic levitation train shown in this utility model.

[0027] Figure 3 This is a schematic diagram of the structure of the insulating layer shown in this utility model. Detailed Implementation

[0028] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0029] Combination Figure 1 and Figure 2 As shown, the power supply cable for maglev trains according to this embodiment of the present invention includes a conductor 1, a semi-conductive wrapping layer 2, an insulation layer 3, a semi-conductive shielding layer 4, a braided shielding layer 5, a wrapping shielding layer 6, and an outer sheath 7.

[0030] Conductor 1 comprises a multilayer stranded conductor, which includes an inner stranded conductor and an outer stranded conductor. The outer stranded conductor is a fan-shaped compacted stranded conductor. In this way, by setting the outer layer as a fan-shaped stranded conductor, the fill rate of the outer layer of the conductor can be effectively increased, reducing the impedance increase caused by the skin effect.

[0031] Combination Figure 2As shown, conductor 1 includes a circular stranded conductor 11 at the center and a sector-shaped stranded conductor 12 on the outer layer. The circular stranded conductor 11 includes a steel-core aluminum stranded wire structure, and the sector-shaped stranded conductor 12 includes an aluminum stranded wire structure with a sector-shaped cross section. The semiconducting resistive water tape is wrapped between the circular stranded conductor 11 and the sector-shaped stranded conductor 12 to reduce the electric field distortion at the interface between the inner and outer stranded conductors.

[0032] Specifically, the inner layer of circular stranded conductors ensures mechanical stability, and the steel core has good support and tensile strength. The outer layer of fan-shaped stranded conductors can disperse high-frequency current paths, especially reducing the impedance increase caused by the skin effect.

[0033] Furthermore, a semiconductive cladding layer 2 is wrapped around the outer wall of the conductor 1, and the semiconductive cladding layer 2 includes a semiconductive resistive water-wound cladding layer. Filling the space between the insulating layer 3 and the conductor 1 can balance the electric field between the two, while filling the gap between the conductor and the insulation, thus achieving a water-blocking effect.

[0034] Furthermore, the insulating layer 3 is extruded onto the outer wall of the semiconductive wrapping layer 2.

[0035] Combination Figure 2 As shown, the insulation layer 3 includes an inner insulation layer 31 and an outer insulation layer 32. The inner insulation layer 31 includes a high-density polyethylene insulation layer, and the outer insulation layer 32 includes a gradient foam insulation layer. The pore size of the gradient foam insulation layer decreases sequentially from the inside of the cable to the outside.

[0036] Thus, the high-density polyethylene insulation layer in the inner layer can ensure reliable dielectric strength, while the gradient foam insulation layer in the outer layer can reduce energy loss during the polarization process in the dielectric and reduce heat loss.

[0037] The thickness ratio of the inner insulating layer 31 to the outer insulating layer 32 is preferably 1:3 to 1:4. The porosity of the gradient foamed insulating layer is 40±5%. The pore size within the gradient foamed insulating layer is preferably 10 to 50 micrometers.

[0038] In an optional embodiment, combined with Figure 3 As shown, the gradient foamed insulation layer includes a macroporous thickness layer 321, a mesoporous thickness layer 322, and a microporous thickness layer 323. The pore size in the macroporous thickness layer 321 is 30-50 micrometers, the pore size in the mesoporous thickness layer 322 is 20-40 micrometers, and the pore size in the microporous thickness layer 323 is 10-30 micrometers.

[0039] Thus, the micropores inside the inner large-pore thickness layer 321 can absorb the electric field distortion on the conductor surface, and at the same time have a lower density, which can reduce the thermal conductivity of the insulating layer and form a thermal barrier. The micropores in the outer micropore thickness layer 323 can suppress surface discharge, and at the same time have higher mechanical strength than the inner layer to avoid deformation due to external extrusion.

[0040] Specifically, the inner insulation layer 31 and the outer insulation layer 32 can be formed by extrusion using a twin-screw co-extrusion system. The inner insulation layer 31 is formed by extruding a high-density polyethylene insulation layer using a main extruder, while the outer insulation layer 32 is formed by injecting a blend of supercritical CO2 and XLPE using a secondary extruder, and achieving micron-level dispersion through a dynamic mixer.

[0041] Furthermore, the semiconductive shielding layer 4 covers the outer wall of the insulating layer 3, the braided shielding layer 5 covers the outer wall of the semiconductive shielding layer 4, and the wrapping shielding layer 6 covers the outer wall of the braided shielding layer 5.

[0042] Optionally, the semi-conductive shielding layer 4 includes a two-layer semi-conductive nylon wrapping tape. By setting the semi-conductive nylon wrapping tape outside the insulation layer, it can serve as a transition interface between the braided shielding layer 5 and the insulation layer, avoiding the accumulation of surface charge on the insulation layer. At the same time, the nylon tape has good elasticity and elongation at break, which is beneficial for absorbing mechanical stress when the cable bends and vibrates.

[0043] Furthermore, the braided shielding layer 5 includes a copper wire loose-wound shielding layer, with the copper wire loosely wound in a left-hand direction, and the wrapped shielding layer 6 includes a copper strip wrapped shielding layer, with the copper strip wrapped in a right-hand direction.

[0044] Specifically, the copper wire has a diameter of 0.8 mm, a pitch of 352~432 mm, a thickness of 0.1 mm, and is wrapped with a layer of non-woven fabric with an overlap rate of not less than 15% and a thickness of 0.2 mm.

[0045] A better shielding effect is achieved by loosely winding copper wire and wrapping copper strip. At the same time, wrapping non-woven fabric around the copper strip can improve the tightness of the wrapping and prevent the copper strip from directly contacting the outer sheath.

[0046] Furthermore, the outer sheath 7 is extruded onto the outer wall of the wrapping shielding layer 6, and the outer sheath 7 is preferably a high-density polyethylene sheath.

[0047] In conjunction with the above embodiments, this utility model sets the conductor to an inner layer of circular stranded conductor and an outer layer of fan-shaped stranded conductor, which can reduce the impedance increase caused by the skin effect. At the same time, the insulation layer is set as a double insulation layer, with the inner layer using a high-density polyethylene structure and the outer layer using a gradient foaming structure, which can effectively reduce the skin depth of high-frequency current. The gradient pores compensate for the change in dielectric constant caused by temperature, resulting in more stable impedance matching and enabling the cable to have high-frequency transmission performance. In addition, the low dielectric constant foaming layer also reduces the eddy current loss of the shielding layer, improving the overall thermal stability of the cable and enabling higher current carrying capacity.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A power feeding cable for a magnetic levitation train, characterized by comprising: include: Conductor (1), said conductor (1) comprising a multilayer stranded conductor; A semiconducting cladding (2) covers the outer wall of the conductor (1); An insulating layer (3) is extruded onto the outer wall of the semiconductive wrapping layer (2); A semiconductive shielding layer (4) covers the outer wall of the insulating layer (3); A braided shielding layer (5) is wrapped around the outer wall of the semiconductive shielding layer (4); The wrapping shielding layer (6) covers the outer wall of the braided shielding layer (5); The outer sheath (7) is extruded onto the outer wall of the wrapping shielding layer (6); The multilayer stranded conductor includes an inner stranded conductor and an outer stranded conductor. The outer stranded conductor is a fan-shaped compacted stranded conductor. The insulation layer (3) includes an inner insulation layer (31) and an outer insulation layer (32). The inner insulation layer (31) includes a high-density polyethylene insulation layer. The outer insulation layer (32) includes a gradient foamed insulation layer. The pore size of the gradient foamed insulation layer decreases sequentially from the inside of the cable to the outside.

2. The power feeding cable for a magnetic levitation train according to claim 1, characterized by The porosity of the gradient foamed insulation layer is 40±5%.

3. The power supply cable for maglev trains according to claim 1, characterized in that, The pore size in the gradient foamed insulation layer is 10~50 micrometers.

4. The power feeding cable for a magnetic levitation train according to claim 1, wherein The gradient foamed insulation layer includes a macroporous thickness layer (321), a mesoporous thickness layer (322), and a microporous thickness layer (323). The pore size in the macroporous thickness layer (321) is 30-50 micrometers, the pore size in the mesoporous thickness layer (322) is 20-40 micrometers, and the pore size in the microporous thickness layer (323) is 10-30 micrometers.

5. The power feeding cable for a magnetic levitation train according to any one of claims 1 to 4, characterized in that, The thickness ratio of the inner insulation layer (31) to the outer insulation layer (32) is 1:3 to 1:

4.

6. The power feeding cable for a magnetic levitation train according to claim 1, wherein The conductor (1) includes a circular stranded conductor (11) at the center and a fan-shaped stranded conductor (12) on the outer layer. The circular stranded conductor (11) includes a steel-core aluminum stranded wire structure, and the fan-shaped stranded conductor (12) includes an aluminum stranded wire structure with a fan-shaped cross section.

7. The power feeding cable for a magnetic levitation train according to claim 1, wherein The semiconducting wrapping layer (2) includes a semiconducting resistive water wrapping layer.

8. The power feeding cable for a magnetic levitation train according to claim 1, wherein The semi-conductive shielding layer (4) includes a semi-conductive nylon wrapping tape, with two wrapping layers.

9. The power feeding cable for a magnetic levitation train according to claim 1, wherein The braided shielding layer (5) includes a copper wire loose-wound shielding layer, the copper wire being loosely wound in the left direction, and the wrapped shielding layer (6) includes a copper strip wrapped shielding layer, the copper strip being wrapped in the right direction.

10. The power feeding cable for a magnetic levitation train according to claim 1, wherein The outer sheath (7) includes a high-density polyethylene sheath.

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