Power transmission device and power transmission system

Abstract

To suppress generation of insulation breakdown.SOLUTION: A power transmission device comprises: a first conductor to which a positive DC voltage is applied; a second conductor to which a negative DC voltage is applied; a first spacer of an insulator of separating the first and second conductors; a second spacer; and a conduit tube. The first spacer has: a first surface with a plurality of first projections and a plurality of first recesses facing the first conductor; and a second surface with a plurality of second projections and a plurality of second recesses facing the second conductor. Each first recess is disposed so as to encompass each position on the first surface penetrated by each line connecting each contact point between the second conductor and each second projection with the first conductor at the shortest distance, and each second recess is disposed so as to encompass each position on the second surface penetrated by each line connecting each contact point between the first conductor and each first projection with the second conductor, at the shortest distance.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a power transmission device and a power transmission system.

Background Art

[0002] Patent Documents 1 and 2 show configuration examples of cables for power transmission. The cables described in Patent Documents 1 and 2 include a conductor that defines a hollow interior, a casing that surrounds the conductor, an electrical insulator disposed between the conductor and the casing, and a fluid disposed in the hollow interior of the conductor. In this configuration, the electrical insulator disposed between the conductor and the casing is a pressurized fluid, a solid, or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the cables described in Patent Documents 1 and 2, when the electrical insulator is a pressurized fluid, there is a problem that if the pressurized state cannot be maintained due to, for example, leakage from the casing under high-altitude conditions, dielectric breakdown may occur.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a power transmission device and a power transmission system capable of suppressing the occurrence of dielectric breakdown.

Means for Solving the Problems

[0006] To solve the above problems, the power transmission device according to the present disclosure includes a first conductor to which a positive voltage of direct current power is applied, a second conductor to which a negative voltage of the direct current power is applied, a first spacer of an insulator that separates the first conductor and the second conductor, a second spacer of an insulator that has a hollow portion and encloses the first conductor, the second conductor, and the first spacer in the hollow portion, and a wire pipe of a conductor that encloses the second spacer. The first spacer has a first surface facing the first conductor and a second surface facing the second conductor. The first surface has a plurality of first protrusions and a plurality of first recesses, and the second surface has a plurality of second protrusions and a plurality of second recesses. Each of the first recesses is arranged so as to include each position where each line connecting the contact points between the second conductor and each of the second protrusions and the first conductor penetrates the first surface. Each of the second recesses is arranged so as to include each position where each line connecting the contact points between the first conductor and each of the first protrusions and the second conductor penetrates the second surface.

[0007] The power transmission system according to the present disclosure includes one or more of the above power transmission devices, an AC-DC power conversion device that is housed in a first housing, inputs AC power, converts it into DC power, and outputs the DC power to the power transmission device, a DC-AC power conversion device that is housed in a second housing, inputs DC power from the power transmission device, converts it into AC power, and outputs the AC power, a pressurizing unit that introduces pressurized fluid into one or more of the power transmission devices, the first housing, and the second housing, and an exhaust unit that exhausts pressurized fluid from one or more of the power transmission devices, the first housing, and the second housing.

Effect of the Invention

[0008] According to the power transmission device and the power transmission system of the present disclosure, the occurrence of dielectric breakdown can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] <First Embodiment> Referring to FIGS. 1 to 11, a power transmission device according to a first embodiment of the present disclosure will be described. FIG. 1 is a cross-sectional view of the power transmission device according to the first embodiment of the present disclosure. FIG. 2 is a perspective view of the power transmission device according to the first embodiment of the present disclosure. FIG. 3 is a perspective view of a conductor and a spacer according to the first embodiment of the present disclosure. FIG. 4 is a perspective view of the spacer according to the first embodiment of the present disclosure. FIG. 5 is a perspective view of an electric wire pipe according to the first embodiment of the present disclosure. In each figure, the same or corresponding components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, the terms "first", "second", "third", and "fourth" used in this specification are interchangeably used to distinguish one component from another component.

[0011] As shown in FIGS. 1 to 5, a power transmission device 1 according to the first embodiment of the present disclosure includes a first conductor 11, a second conductor 12, a first spacer 13, a second spacer 14, and an electric wire pipe 15. The power transmission device 1 is a device for transmitting DC power.

[0012] The first conductor 11 and the second conductor 12 are electric wires that constitute the main line of the DC power circuit. A positive voltage (positive electrode) of DC power is applied to the first conductor 11, and a negative voltage (negative electrode) of DC power is applied to the second conductor 12. In this embodiment, a conductor is a substance having a relatively high electrical conductivity, and can be made of, for example, copper, aluminum, or other metals.

[0013] The first spacer 13 is an insulator that separates the first conductor 11 and the second conductor 12. In this embodiment, an insulator is an object through which current hardly flows. The second spacer 14 has a hollow portion 141 and is an insulator that encloses the first conductor 11, the second conductor 12, and the first spacer 13 in the hollow portion 141. The second spacer 14 separates the first conductor 11 and the second conductor 12 from the wire conduit 15. The wire conduit 15 is a conductor that encloses the second spacer 14. The wire conduit 15 is formed of a metal such as aluminum, for example. The wire conduit 15 can also be referred to as a metal conduit or the like. A fluid 16 such as air at atmospheric pressure, a pressurized gas, or a pressurized fluid such as a liquid is introduced into the wire conduit 15. The fluid 16 forms an insulating layer and functions as a cooling medium for air-cooling or water-cooling the first conductor 11, the second conductor 12, etc. Also, the wire conduit 15 can be grounded, for example.

[0014] Note that between the first conductor 11 and the second conductor 12 and the first spacer 13, between the first conductor 11 and the second conductor 12 and the second spacer 14, and between the second spacer 14 and the wire conduit 15, they are combined in a state allowing contact or a certain gap and are not fixed to each other. However, each component may be fixed as appropriate. For example, the contact state or gap between the first conductor 11 and the second conductor 12 and the first spacer 13, between the first conductor 11 and the second conductor 12 and the second spacer 14, and between the second spacer 14 and the wire conduit 15 changes depending on, for example, the temperature state or the magnitude of the repulsive force acting between the first conductor 11 and the second conductor 12 due to electromagnetic force.

[0015] The first spacer 13 has a first surface 131 facing the first conductor 11 and a second surface 132 facing the second conductor 12. The first surface 131 has a plurality of first convex portions 133 and a plurality of first concave portions 134, and the second surface 132 has a plurality of second convex portions 135 and a plurality of second concave portions 136. As shown in FIG. 6, each first concave portion 134 is arranged so as to include each position PA where each line LA connecting each contact point 137 between the second conductor 12 and each second convex portion 135 and the first conductor 11 penetrates the first surface 131. Further, each second concave portion 136 is arranged so as to include each position PB where each line LB connecting each contact point 138 between the first conductor 11 and each first convex portion 133 and the second conductor 12 penetrates the second surface 132.

[0016] According to this configuration, between the portions of the first conductor 11 and the second conductor 12 where a potential difference is generated, an insulating material layer formed by the first spacer 13 and a fluid layer such as an air layer formed by a fluid 16 such as air are always arranged in series. Therefore, according to this configuration, even if dielectric breakdown of the fluid layer occurs, the dielectric breakdown can be prevented by the insulating material layer, so that the occurrence of dielectric breakdown between the first conductor 11 and the second conductor 12 can be suppressed.

[0017] Further, as shown in FIGS. 4 and 6, the second spacer 14 has a third surface 142 facing the wire conduit 15. The third surface 142 has a plurality of third concave portions 143. Further, as shown in FIG. 6, each third concave portion 143 is arranged so as to include each position PC where each line LC connecting each contact point 145 between the fourth surface 144 of the second spacer 14 forming the hollow portion 141 and the first conductor 11 or the second conductor 12 and the wire conduit 15 penetrates the third surface 142.

[0018] According to this configuration, between the portions of the first conductor 11 and the second conductor 12 where a potential difference is generated and the wire conduit 15, an insulating material layer formed by the second spacer 14 and a fluid layer such as an air layer formed by a fluid 16 such as air are always arranged in series. Therefore, according to this configuration, even if dielectric breakdown of the fluid layer occurs, the dielectric breakdown can be prevented by the insulating material layer, so that the occurrence of dielectric breakdown between the first conductor 11 and the second conductor 12 and the wire conduit 15 can be suppressed.

[0019] Also, in the present embodiment, as shown in FIG. 1, the first conductor 11 and the second conductor 12 face the first spacer 13 and include a first plate-like portion B1 that extends in the DC power transmission direction and one or more second plate-like portions B2 that extend in the direction of the fourth surface 144 with the first plate-like portion B1 as a base end portion B11. Further, the one or more second plate-like portions B2 include a plate-like portion B21 that extends in a direction perpendicular to the plate surface B12 of the first plate-like portion B1. According to this configuration, it is possible to achieve a good balance between improving the cooling efficiency (such as increasing the surface area and decreasing the resistance value) and reducing the weight.

[0020] Note that the shapes of the first spacer 13 and the second spacer 14 are not limited to those described above. For example, as in the case of the first spacer 13a shown in FIG. 7, the first convex portion 133, the first concave portion 134, the second convex portion 135, and the second concave portion 136 may be discontinuous with respect to the DC power transmission direction. FIG. 7 is a perspective view of another example (the first spacer 13a) of the first spacer 13 according to the first embodiment of the present disclosure.

[0021] Next, with reference to FIGS. 8 to 11, setting examples of the shapes of each part and the like will be described. FIG. 8 is a partially enlarged cross-sectional view of a spacer and a conductor according to the first embodiment of the present disclosure. FIG. 9 is a diagram showing an example of the relationship (both logarithmic scales) between the gap length g and the gap electric field Eg between the conductor and the spacer according to the first embodiment of the present disclosure. FIGS. 10 and 11 are diagrams showing examples of the creepage distance between the conductors according to the first embodiment of the present disclosure. FIG. 8 shows a partial enlargement of the contact portion between the first conductor 11 and the second spacer 14. The first conductor 11 and the second conductor 12 have a curved surface shape at the portion CP that contacts the fourth surface 144. The curved surface shape of the portion CP is set by performing a simulation by the finite element method or the like, obtaining the relationship between the gap length g and the gap electric field Eg shown in FIG. 9, and avoiding the discharge region. Also, as shown in FIGS. 10 and 11, regarding the creepage distance CP1 of the first spacer 13 between the first conductor 11 and the second conductor 12 and the creepage distance CP2 of the second spacer 14 between the first conductor 11 and the second conductor 12, the shapes of the first conductor 11, the second conductor 12, and the first spacer 13 are set so as to ensure the necessary creepage distance.

[0022] According to the present embodiment as described above, between the first conductor 11 and the second conductor 12 where a potential difference occurs, and between the first conductor 11 and the second conductor 12 and the conduit 15, a fluid layer such as an air layer and an insulating material layer are arranged in series, so that the occurrence of dielectric breakdown can be suppressed. Further, since the shape of the conductor and the insulating material is adopted such that the creepage distance along the insulating material where a high voltage occurs is equal to or greater than the insulation distance, the resistance to insulation can be improved.

[0023] In addition, in the present embodiment, since the reciprocating current path is placed inside the metal tube, it is easier to reduce the weight compared to the case where the forward path and the return path are configured using separate cables. Further, since the positive and negative conductors face each other, the Coulomb force can be increased to suppress radiation, and electromagnetic radiation can be reduced.

[0024] <Second Embodiment> Next, as the second embodiment, the material selection according to the concept will be described. In the present embodiment, by selecting a high heat-resistant material for the insulating material in contact with the transmission line (conductor), the cooling margin is significantly improved. Also, materials can be selected according to the concept under the conditions established in terms of electric field, cooling, and strength. For example, multiple adoptable specifications are prepared so that if weight is emphasized, the material of the conductor can be aluminum, and if transmission efficiency is emphasized, copper can be selected. FIG. 12 shows an example of setting the material specifications. By using a high heat-resistant material such as fluororesin for the insulating material, the upper limit of the heat generation temperature of the transmission line increases, so the cooling flow rate (flow velocity) can be decreased, and a practical solution can be obtained. Also, it was confirmed that by selecting copper or aluminum as the material of the transmission line, it can be reflected in the design that emphasizes weight (lightweight: aluminum) and emphasizes efficiency (low loss: copper).

[0025] <Third Embodiment> Next, with reference to FIGS. 13 to 15, a case where the power transmission device 1 of the first embodiment is applied to an aircraft will be described as a third embodiment. FIGS. 13 to 15 are schematic diagrams showing a configuration example of a power transmission system according to the third embodiment of the present disclosure. The aircraft 20 shown in FIG. 13 is an electric aircraft that transmits the power generated by a generator 22 driven by an aircraft engine 21 to a transmission line 102 for DC power transmission and drives a boundary layer ingestion (BLI) fan 23 provided at the rear. The transmission line 102 is configured by using a plurality of the power transmission devices 1 of the first embodiment. However, the transmission line 102 may be configured by one power transmission device 1. The power transmission system 100 includes a generator 22, a converter (AC-DC power conversion device) 101 that inputs the AC power generated by the generator 22, converts it into DC power, and outputs it to the power transmission device 1, a transmission line 102, and an inverter (DC-AC power conversion device) 103 that inputs DC power from the power transmission device 1, converts it into AC power, and outputs it.

[0026] The power transmission system 100 shown in FIG. 13, for example, as shown as the power transmission system 100A in FIG. 14, includes a transmission line 102 (one or a plurality of power transmission devices 1), a converter 101 housed in a first housing 104-1, an inverter 103 housed in a second housing 104-2, a pressurizing unit 105 such as a pump that introduces a pressurized fluid such as air into the transmission line 102, the first housing 104-1, and the second housing 104-2, and an exhaust unit 106 that exhausts the pressurized fluid while maintaining a pressurized state from the transmission line 102, the first housing 104-1, and the second housing 104-2. The wire pipe 15 of the power transmission device 1 and the first housing 104-1 and the second housing 104-2 are electrically connected by a connection part 111 and are sealed so that the power transmission device 1, the first housing 104-1, and the second housing 104-2 integrally form a pressurized space.

[0027] FIG. 15 shows another configuration example of the power transmission system 100 shown in FIG. 13 as a power transmission system 100B. In the power transmission system 100B shown in FIG. 15, the transmission line 102 (power transmission device 1), the first housing 104-1, and the second housing 104-2 each form a pressurized space. Flanges 112-1 and 112-2 are provided at both ends of the wire pipe 15 of the power transmission device 1, and a sealed space is formed by the wire pipe 15 and the flanges 112-1 and 112-2. In this case, the pressurizing unit 105 includes a pressurizing unit 105-1 for introducing a pressurized fluid into the power transmission device 1, a pressurizing unit 105-2 for introducing a pressurized fluid into the first housing 104-1, and a pressurizing unit 105-3 for introducing a pressurized fluid into the second housing 104-2. Further, the power transmission line between the power transmission device 1 and the first housing 104-1 and the second housing 104-2 passes through a non-pressurized region, so power is transmitted using, for example, a thick film wire CW having insulation properties.

[0028] According to the present embodiment, since the breakdown voltage of a fluid layer such as air can be increased by pressurization, the occurrence of dielectric breakdown in the transmission line 102, the converter 101, and the inverter 103 can be suppressed.

[0029] <Fourth Embodiment> Next, the fourth embodiment will be described with reference to FIGS. 16 and 17. In this embodiment, an electric conduit 15 (metal conduit) with low resistance functions as a current return path (return wire for power transmission). In the power transmission systems 100C and 100D shown in FIGS. 16 and 17, the electric conduit 15 is used as an electrical connection that also serves as the current return path in the airframe structure, significantly reducing the number of current return paths. According to this embodiment, for example, by connecting both ends of the electric conduit 15 to the airframe, a lightning current can be passed, and the effect of significantly reducing the number of current return paths made of copper wires required for the airframe structure can be obtained. For example, the metal conduit resistance of the electric conduit 15 (Φ120mm, thickness 2.5mm, about 3 uΩ / m for aluminum. Even if a total lightning current of 200 kA flows through a 10m metal conduit, the voltage generated at both ends is about 6V (3E - 6×200E3), and the impact on the system is acceptable. Note that the power transmission system 100C shown in FIG. 16 is for a power transmission method of a single - pole conductor return system, and the power transmission system 100D shown in FIG. 17 is for a power transmission method of a bipolar neutral - line conductor system.

[0030] (Other Embodiments) As described above, the embodiments of the present disclosure have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included. For example, the shapes of the first conductor 11 and the second conductor 12 are not limited to those described above. For example, the number of the second plate - like portions B2 is not limited to three, and may be two or less or four or more. Also, the second plate - like portion B2 may have a shape extending radially from the first plate - like portion B1, for example.

[0031] <Appendix> The power transmission device 1 and the power transmission system 100 described in each embodiment can be understood as follows, for example.

[0032] (1) The power transmission device 1 according to the first aspect includes a first conductor 11 to which a positive voltage of direct current power is applied, a second conductor 12 to which a negative voltage of the direct current power is applied, a first spacer 13 of an insulator that separates the first conductor 11 and the second conductor 12, a second spacer 14 of an insulator that has a hollow portion 141 and encloses the first conductor 11, the second conductor 12, and the first spacer 13 in the hollow portion 141, and a wire pipe 15 of a conductor that encloses the second spacer 14. The first spacer 13 has a first surface 131 facing the first conductor 11 and a second surface 132 facing the second conductor 12. The first surface 131 has a plurality of first convex portions 133 and a plurality of first concave portions 134, and the second surface 132 has a plurality of second convex portions 135 and a plurality of second concave portions 136. Each of the first concave portions 134 is arranged so as to include each position PA where each line LA that connects the first conductor 11 and each contact point 137 between the second conductor 12 and each of the second convex portions 135 passes through the first surface 131 at the shortest distance. Each of the second concave portions 136 is arranged so as to include each position PB where each line LB that connects the second conductor 12 and each contact point 138 between the first conductor 11 and each of the first convex portions 133 passes through the second surface 132 at the shortest distance. According to this aspect and the following aspects, the occurrence of dielectric breakdown can be suppressed.

[0033] (2) The power transmission device 1 according to the second aspect is the power transmission device 1 in (1), wherein the second spacer 14 has a third surface 142 facing the wire pipe 15, the third surface 142 has a plurality of third concave portions 143, and each of the third concave portions 143 is arranged so as to include each position PC where each line LC that connects the wire pipe 15 and each contact point 145 between the fourth surface 144 of the second spacer that forms the hollow portion 141 and the first conductor 11 or the second conductor 12 passes through the third surface 142 at the shortest distance.

[0034] (3) The power transmission device 1 according to the third aspect is the power transmission device 1 in (1) or (2), wherein the first conductor 11 and the second conductor 12 include a first plate-like portion B1 that faces the first spacer 13 and extends in the transmission direction of direct current power, and one or a plurality of second plate-like portions B2 that extend in the direction of the fourth surface 144 with the first plate-like portion B1 as a base end portion B11.

[0035] (4) The power transmission device 1 according to the fourth aspect is the power transmission device 1 of (3), wherein one or more of the second plate-like portions B2 include a plate-like portion B21 extending in a direction perpendicular to the plate surface B12 of the first plate-like portion B1.

[0036] (5) The power transmission device 1 according to the fifth aspect is the power transmission device 1 of (2) to (4), wherein the first conductor 11 and the second conductor 12 have a curved surface shape (portion CP) at the portion in contact with the fourth surface 144.

[0037] (6) The power transmission device 1 according to the sixth aspect is the power transmission device 1 of (1) to (5), wherein a pressurized fluid is introduced into the wire conduit 15.

[0038] (7) The power transmission device 1 according to the seventh aspect is the power transmission device 1 of (1) to (6), which is mounted on an aircraft, and the wire conduit 15 is connected to the return line of power transmission.

[0039] (8) The power transmission system 100 (100A and 100B) according to the eighth aspect includes one or more power transmission devices 1 of (1) to (7), an AC-DC power conversion device (converter 101) housed in the first housing 104-1 that inputs AC power, converts it into DC power, and outputs it to the power transmission device, a DC-AC power conversion device (inverter 103) housed in the second housing 104-2 that inputs DC power from the power transmission device, converts it into AC power, and outputs it, a pressurizing unit that introduces a pressurized fluid into one or more of the power transmission devices, the first housing, and the second housing, and an exhaust unit that exhausts the pressurized fluid from one or more of the power transmission devices, the first housing, and the second housing.

[0040] (9) The power transmission system 100A according to the ninth aspect is the power transmission system 100A of (8), wherein one or more of the power transmission devices, the first housing, and the second housing integrally form a pressurized space.

Explanation of Reference Numerals

[0041] 1…Power transmission device 100…Power transmission system 11…First conductor 12…Second conductor 13…First spacer 14…Second spacer 15…Conduit 16…Fluid

Claims

1. a first conductor to which a positive voltage of direct current power is applied; a second conductor to which a negative voltage of the direct current power is applied; a first spacer of an insulator that separates the first conductor and the second conductor; a second spacer of an insulator that has a hollow portion and encloses the first conductor, the second conductor, and the first spacer in the hollow portion; a wire pipe of a conductor that encloses the second spacer; comprising; the first spacer has a first surface facing the first conductor and a second surface facing the second conductor; the first surface has a plurality of first convex portions and a plurality of first concave portions; the second surface has a plurality of second convex portions and a plurality of second concave portions; each of the first concave portions is arranged so as to include each position where each line connecting the first conductor and each contact point between the second conductor and each of the second convex portions penetrates the first surface at the shortest distance; each of the second concave portions is arranged so as to include each position where each line connecting the second conductor and each contact point between the first conductor and each of the first convex portions penetrates the second surface at the shortest distance. A power transmission device.

2. the second spacer has a third surface facing the wire pipe; the third surface has a plurality of third concave portions; each of the third concave portions is arranged so as to include each position where each line connecting the wire pipe and each contact point between the fourth surface of the second spacer forming the hollow portion and the first conductor or the second conductor penetrates the third surface at the shortest distance; The power transmission device according to claim 1.

3. the first conductor and the second conductor include a first plate-shaped portion that faces the first spacer and extends in the power transmission direction of direct current power, and one or a plurality of second plate-shaped portions that extend in the direction of the fourth surface with the first plate-shaped portion as a base end portion; The power transmission device according to claim 2.

4. one or a plurality of the second plate-shaped portions include a plate-shaped portion extending in a direction perpendicular to the plate surface of the first plate-shaped portion; The power transmission device according to claim 3.

5. the first conductor and the second conductor have a curved surface shape at a portion in contact with the fourth surface; The power transmission device according to claim 4.

6. a pressurized fluid is introduced into the wire pipe; The power transmission device according to claim 5.

7. mounted on an aircraft, the wire pipe is connected to a return wire for power transmission; The power transmission device according to any one of claims 1 to 6.

8. one or a plurality of power transmission devices according to claim 1; an AC-DC power conversion device that is housed in a first housing, inputs AC power, converts it into DC power, and outputs it to the power transmission device; An orthogonal power conversion device that is housed in the second housing, inputs DC power from the power transmission device, converts it into AC power, and outputs the AC power. A pressurizing unit that introduces pressurized fluid into one or more of the power transmission devices, the first housing, and the second housing. An exhaust unit that exhausts pressurized fluid from one or more of the power transmission devices, the first housing, and the second housing. A power transmission system comprising the above.

9. One or more of the power transmission devices, the first housing, and the second housing integrally form a pressurized space. The power transmission system according to claim 8.

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