Enclosure

Abstract

The present disclosure relates to an enclosure for an electrical device in a high voltage electric field, the enclosure comprising at least one upper element and at least one corresponding lower element extending circumferentially from a central portion, the upper and lower elements being plate-like elements arranged substantially parallel to each other at a predetermined distance to provide a space therebetween. Each of the upper and lower elements is electrically connected at one end of the central portion and electrically contacts at its respective circumferential end to form at least part of the enclosure. The enclosure is at least partially constructed of a conductive material. At least two slots extending from the central portion to the peripheral edge are provided in the enclosure to separate different parts of the enclosure.

Description

Technical Field

[0001] The present disclosure relates to an enclosure for an electrical device in a high voltage electric field. In particular, the present disclosure relates to a multi-functional shielding enclosure for a wireless device in a high voltage environment.

Background Art

[0002] The use of wireless transmission of data and power in high voltage equipment is increasing as a result of the introduction of more sensors and remote control systems. Often, this involves placing small devices, including electronic equipment and wireless transmitters or receivers, in very harsh electromagnetic environments. Some examples may include power transformers, substations, and HVDC converter stations. In particular, very high electric fields can interfere with electronic equipment or cause partial discharges due to electric field enhancement on the surface of the inserted device. Therefore, some kind of electric field grading and electrical shielding of the electronic equipment is required. However, since wireless power transmission to the electronic equipment is necessary when wires cannot be used in a strong electric field environment, complete shielding is not desirable. Therefore, the shielding enclosure must be permeable to the magnetic field used for power transmission. A further problem is designing an antenna that enables high frequency data communication with the device. Placing the antenna element outside the shielding enclosure necessarily increases the risk of strong electric field enhancement, resulting in partial discharges.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Therefore, it is necessary to satisfy at least one of the following requirements: - Efficiently shield an external, e.g., 50 / 60 Hz AC electric field, while minimizing electric field enhancement just outside the enclosure.

[0004] - Allowing an externally imposed magnetic field (e.g., a typical frequency in the MHz range) used for wireless power transmission to reach inside the enclosure where the pickup coil is disposed.

[0005] - The enclosure itself is designed to be able to be used as an antenna element for high-frequency (e.g., GHz range) data communication.

Means for Solving the Problems

[0006] The present disclosure relates to an enclosure. Various exemplary embodiments of the present disclosure disclosed herein are directed to providing features that will be readily apparent by reference to the following description in conjunction with the accompanying drawings. According to various embodiments, exemplary systems, methods, and devices are disclosed herein. However, it is understood that these embodiments are presented by way of example and not limitation, and it will be apparent to those skilled in the art having read this disclosure that various modifications to the disclosed embodiments can be made within the scope of the present disclosure.

[0007] Accordingly, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. Further, the specific order and / or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based on design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be rearranged while remaining within the scope of the present disclosure. Accordingly, those skilled in the art will understand that the methods and techniques disclosed herein present various steps or operations in a sample order, and the present disclosure is not limited to the specific order or hierarchy presented unless otherwise specified.

[0008] The above and other aspects and their implementations are described in more detail in the drawings, description, and claims.

[0009] Description of the Drawings

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0011] Hereinafter, exemplary embodiments of the present disclosure will be described. Note that some aspects of any one of the described embodiments can also be found in some other embodiments unless specifically stated or obvious. However, for the sake of better understanding, each aspect will be described in detail only when first mentioned, and repeated descriptions of the same aspect will be omitted.

[0012] The present disclosure relates to an enclosure for an electrical device in a high-voltage electric field, the enclosure comprising at least one upper element and at least one corresponding lower element extending circumferentially from a central portion, the upper and lower elements being plate-like elements arranged substantially parallel to each other at a predetermined distance to provide a space therebetween. Each of the upper and lower elements is electrically connected at one end of the central portion and electrically contacts at its respective circumferential end to form at least part of the enclosure. The enclosure is at least partially constructed of a conductive material. To separate different parts of the enclosure, at least two slots extending from the central portion to the peripheral portion are provided in the enclosure.

[0013] Various embodiments may implement, in particular, the following features. The upper and lower elements may be configured to be oriented substantially perpendicular to the direction of the electric field.

[0014] The enclosure may be configured to enable wireless power transfer to the space. The enclosure may be divided into two parts at the central portion. An antenna feeding circuit may be connected to both parts of the enclosure.

[0015] The upper and lower elements may be connected by a connection portion at the peripheral edge of the upper and lower elements. In particular, the upper element, the lower element, and the connection portion are integrally formed.

[0016] The slots may be provided symmetrically with respect to the central portion. The upper and lower elements forming part of the enclosure may form a circular sector around the central portion. The radii of the upper and lower elements may in particular be between 5 mm and 75 mm. The distance between the upper and lower elements may in particular be between 5 mm and 15 mm.

[0017] The upper element, the lower element, and the connection portion may each include their respective thickness and their respective conductivity.

[0018] The space may be at least partially filled with a dielectric material and an insulating material. An opening may be provided in the enclosure to allow insertion of an electronic device.

[0019] The enclosure may comprise a conductive layer. The width of the slot at the periphery of the present disclosure may be less than 25% of the distance between the upper element and the lower element.

[0020] The distance between the slots at the periphery of the present disclosure may be less than or equal to the distance between the upper element and the lower element.

[0021] The width of the slot may gradually increase from the central portion towards the periphery. In the following, it is assumed that the main direction of the AC electric field, such as in a power transformer, a substation, an HVDC converter station, etc., is well known so that the plane of the enclosure can be oriented substantially perpendicular to the electric field. In this way, the electric field enhancement at the surface of the enclosure is minimized.

[0022] Figure 1 shows an exemplary enclosure according to the present disclosure. The enclosure 1 includes at least one upper element 2 and at least one corresponding lower element 3 that extend circumferentially from a central portion 6. The upper and lower elements 2, 3 are plate-like elements arranged substantially parallel to each other with a predetermined distance therebetween to provide a space therebetween. Each of the upper and lower elements 2, 3 is electrically connected at one end of the central portion 6 and electrically contacts at its respective circumferential ends to form at least a part of the enclosure 1. However, the upper and lower elements 2, 3 do not necessarily have to contact each other at the central portion 6. In other words, there may not be a direct connection between the upper element 2 and the lower element 3 at the central portion. The enclosure 1 is at least partially constructed of a conductive material. To separate different parts of the enclosure 1, at least two slots 5 extending from the central portion 6 to the peripheral edge are provided in the enclosure 1. In Figure 1, E0 indicates the direction of the electric field. The overall shape of the enclosure 1 may be described as a flat pillbox shape.

[0023] The upper element 2 and the lower element 3 may be connected by a connecting portion 4 at the peripheral edges of the upper and lower elements 2, 3. The upper element 2, the lower element 3, and the connecting portion 4 may be integrally formed.

[0024] In other words, the enclosure 1 for an electrical device in a high-voltage electric field may include upper and lower elements 2, 3 having a rounded shape, and the upper and lower elements 2, 3 are plate-like elements arranged parallel to each other. The upper and lower elements 2, 3 may be connected by a connecting portion 4 at their respective peripheral edges to provide a space therebetween to form the enclosure 1. The enclosure 1 may be at least partially constructed of a conductive material, and at least two slots 5 may be provided in the enclosure 1 from the central portion 6 to the peripheral edge to form parts or segments of the enclosure 1, and the central portion 6 of the upper and lower elements 2, 3 electrically connects the parts.

[0025] The overall shape of the enclosure 1 may be, for example, elliptical or circular, and may particularly have a curvature or roundness, in order to avoid the adverse effects of sharp corners on the shielding performance.

[0026] Particularly during use, the upper element and the lower elements 2, 3 may be configured to be oriented substantially perpendicular to the direction of the electric field. Thereby, electrical shielding of the space may be achieved. Furthermore, the enclosure 1 may be configured to enable wireless power transfer to the space inside the enclosure 1.

[0027] Electrical shielding of the internal space of the enclosure 1 is also achieved with respect to other relative directions and the electric field of the enclosure 1. However, if they are not perpendicular to each other, significant electric field enhancement may occur on the outer surface of the enclosure.

[0028] The upper element 2, the lower element 3, and the connection part 4 may each include a respective thickness d and a respective conductivity σ, and the product of the thickness d and the conductivity σ is particularly 5 1 / Ω less than, i.e., 5 S. In principle, the attenuation of the electric field (i.e., the Faraday cage effect) inside the enclosure 1 is not affected by the orientation as long as the product σd is sufficiently large, i.e., σd > 10 -9 S. However, the electric field enhancement just outside the enclosure surface is affected by the said orientation. If this electric field enhancement is too large, it may lead to the occurrence of local discharges there. By orienting the enclosure such that the external electric field is perpendicular to the flat surface of the enclosure, the electric field enhancement can be minimized.

[0029] In order to enable the insertion of an electronic device, the enclosure 1 may be provided with an opening. The electronic device may be configured to provide, for example, operating data or control signals for a power transformer, a substation, an HVDC converter station, etc., to which the enclosure 1 is attached or in the vicinity of which the enclosure is located.

[0030] As shown in FIG. 2, the enclosure 1 may be divided into two parts at the central portion 6. The antenna power supply circuit 7 may be connected to both parts of the enclosure 1. In this way, the enclosure may further function as an antenna for communicating operation data or control signals of a power transformer, a substation, or an HVDC converter station from an electronic device via, for example, the enclosure 1.

[0031] Also, the presence of the gap as shown in FIG. 2 where the antenna power supply circuit 7 (required for the GHz antenna function) is installed requires that the flat surfaces of the upper element and the lower elements 2 and 3 be perpendicular to the electric field. In other orientations, a strong electric field may be generated in the gap region.

[0032] The slot 5 may be provided symmetrically with respect to the central portion 6. The upper element 2 and the lower element 3 forming a part of the enclosure 1 may form a circular sector around the central portion 6. In one example, the radii of the upper element 2 and the lower element 3 are between 5 mm and 75 mm. Assuming a circular enclosure 1, its diameter may be between 10 mm and 150 mm. In one example, the distance between the upper element 2 and the lower element 3 is between 5 mm and 15 mm.

[0033] The space, i.e., the space between the upper element and the lower elements 2 and 3, may be at least partially filled with a dielectric material and an insulating material.

[0034] The enclosure 1 may include a conductive layer. That is, the enclosure 1 may be coated with a conductive layer.

[0035] In one example, the width of the slot 5 at the periphery of the present disclosure is less than 25% of the distance between the upper element 2 and the lower element 3. In one example, the distance between the slots 5 at the periphery of the present disclosure is less than or equal to the distance between the upper element 2 and the lower element 3.

[0036] The width of the slot 5 may gradually increase from the central portion 6 toward the periphery. The exemplary enclosure 1 described with reference to FIGS. 1 and 2 will be described in more detail with respect to the above requirements. The (pillbox-shaped, i.e., circular) enclosure 1 that forms the basis of the following simulations and calculations has a diameter of 100 mm and a thickness of 10 mm. Typically, the diameter is in the range of 10 mm to 150 mm, and the thickness varies between 5 mm and 15 mm. The electronic device is positioned inside the enclosure filled with a dielectric material and an insulating material to provide mechanical support for the conductive enclosure layer. However, the above values and ranges are merely exemplary in nature and the present disclosure is not limited thereto.

[0037] The internal electrical shielding will be described below. The internal low-frequency electrical shielding may be achieved by using a Faraday cage type conductive enclosure 1. In the exemplary example shown in FIG. 1, the cage of the enclosure 1 consists of a thin conductive layer that partially covers the surface of the enclosure 1. Here, the product of the layer conductivity σ and the thickness d must be large enough to reduce the electric field level inside the enclosure 1 to an acceptable level. Typically, σd must be greater than 10 -9 S (10 -9 1 / Ω ). Further, the product σd must be smaller than 5S (i.e., 5 1 / Ω ), and particularly smaller than 1S. The small layer surface, i.e., the central portion 6 close to the axis of symmetry, electrically connects different parts of the enclosure 1, i.e., the respective upper element 2 and lower element 3, further improves the shielding of the non-axial E-field component, and provides some mechanical stability.

[0038] Figure 3 shows the shielding effect of the enclosure 1. In this simulation, an external electric field of E0 = 1 V / m is assumed. Even with a relatively low layer conductivity σ, significant shielding is obtained. It can also be seen that the shielding efficiency is not uniform inside the enclosure 1. In particular, Figure 3 shows plots of the E-field amplitude along two radial lines in each horizontal plane under the conductive layer, i.e., between the upper element 2 and the lower element 3, and under the slot 5. In particular, the graph shows the normalized electric field amplitude (V / m) depending on the radius r (m) under the slot (solid line) and under the layer, i.e., the part described above (dashed line).

[0039] As can be seen from the graph, the exemplary enclosure 1 significantly reduces the electric field, especially under that part, but also significantly reduces the electric field within the slot.

[0040] In the following, the requirements for enabling a magnetic field to pass through the space inside the enclosure 1 to provide wireless power transmission are described.

[0041] The efficiency of wireless power transmission may be optimized when (i) the applied magnetic field is perpendicular to the plane of the pickup coil and (ii) the area of the planar pickup coil, e.g., the area of the electronic device disposed inside the enclosure 1 and requiring power, is as large as possible. These two conditions are met when the internal pickup coil is in the plane of the enclosure 1 and the magnetic field is perpendicular to the same plane. This means that in the case of the present invention, optimized power transmission is obtained when the applied magnetic field is parallel to the strong external electric field.

[0042] However, due to the shielding effect of the induced current within the conductive enclosure layer, the amplitude of the magnetic field is reduced within the enclosure. In order to achieve efficient power transfer, it is consequently necessary to somehow cancel the generation of the induced current. One way to do this is to cut the slots 5 in the layer of the conductive enclosure 1 as described above. Otherwise, by orienting the slots 5 to be perpendicular everywhere with respect to the direction of the induced current, the amplitude of these currents, and thus the attenuation of the magnetic field, is significantly reduced. In the case of the pillbox-shaped enclosure 1 without slots, the induced current circulates in an angular direction around the symmetry axis of the enclosure (which is parallel to the applied magnetic field). Thus, the radial slots 5 are introduced to disrupt the induced current and thus allow the magnetic field to penetrate into the enclosure 1 (the small surface near the symmetry axis, i.e., the central portion 6, has no significant effect). The exemplary designs of FIGS. 1 and 2 show how such slots can be introduced into the enclosure layer. Note that these slots do not break the electrical connection between the upper and lower planes of the enclosure 1. This is important for the functioning of the electrical shielding as outlined above.

[0043] In the simulation shown in FIG. 4, assume that the applied vertical magnetic field has an amplitude |H z | = 1 A / m and oscillates at a frequency f = 13 MHz. Here too, the product of the layer thickness and conductivity is assumed to be σd = 5 S. The vertical component of the magnetic field on a horizontal plane passing through the center of the enclosure 1 is shown in FIG. 4 along two radial lines. The graph in FIG. 4 shows the magnetic field normalized over the radius, with the solid line showing the magnetic field under the slot 5 and the dashed line showing the magnetic field under the layer, i.e., the magnetic field of the portion. The overall attenuation seems suitable for wireless power transfer.

[0044] The requirements for providing an antenna function are described below. Since the layer of the enclosure 1 is conductive, it can be used as an antenna element. The easiest way to achieve this is to make it an electric dipole radiator. This is done by cutting the enclosure 1 (in the shape of a pillar box) into two halves at the central portion 6, as shown in Fig. 2, and connecting the halves of the central portion 6 to each other via the antenna feeding circuit 7 as described above. Thereby, a dipole antenna connected to the feeding circuit 7 is created. For the size of the enclosure 1, i.e., at wavelengths longer than the diameter in this example, the radiated power is distributed omnidirectionally except in the direction close to the direction of the dipole moment. At shorter wavelengths, significant direction dependence occurs.

[0045] It should be noted that the gap generated when dividing the enclosure 1 does not affect the desired electrical shielding nor the magnetic field penetration.

[0046] In the above example, the two halves are created by a cut passing through the central portion 6 as shown in Fig. 2. The direction of the antenna feeding circuit 7 between the two halves is the y-direction, which is also the direction of the dipole moment of the antenna. Solving for the near field and then performing the conversion from the near field to the far field, the radiation patterns shown in Figs. 5 to 7 are obtained. Here too, σd = 5 S is assumed for the simulation. The frequency is assumed to be 2.4 GHz. The quantity shown is the radiated power (in dB), i.e., how much the radiated power density changes as a function of direction. It is observed that the radiated power is distributed fairly uniformly except in the direction of the dipole moment of the antenna, i.e., along the y-axis.

[0047] Figs. 5 to 7 show the radiated power as a two-dimensional plot in the x-y plane (Fig. 5), x-z plane (Fig. 6), and y-z plane (Fig. 7).

[0048] According to the present disclosure, it is possible to design an enclosure that strongly attenuates an external electric field while allowing a magnetic field used for wireless power transmission to penetrate. Further, the enclosure can function as an element of a dipole antenna for communicating with an external device. Through careful design, these three functions can be introduced without interfering with each other. Thus, the above-described features and functions may be combined in a compact design, and the enclosure can be used over a wide range of frequencies and can provide a product that is very robust with respect to electrical, thermal, and mechanical properties.

[0049] Having described various embodiments of the present disclosure above, it should be understood that they are presented by way of example only and not by way of limitation. Similarly, the various figures may depict an exemplary architecture or configuration provided to enable those skilled in the art to understand the exemplary features and functions of the present disclosure. However, such a person will understand that the present disclosure is not limited to the illustrated exemplary architecture or configuration and can be implemented using various alternative architectures and configurations. Further, as will be understood by those skilled in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Accordingly, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

[0050] Also, it should be understood that any reference in this specification to elements using terms such as “first,” “second,” etc. generally does not limit the quantity or order of those elements. Rather, these terms can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, references to a first and second element do not mean that only two elements can be employed, nor that the first element must in any way precede the second element.

[0051] Furthermore, in the claims, the term "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single unit may perform the functions of several features recited in the claims. Terms such as "essentially", "about", "approximately" in relation to an attribute or a value also define the attribute or the value itself, respectively. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An enclosure (1) for an electrical device in a high-voltage electric field, comprising at least one upper element (2) and at least one corresponding lower element (3) extending circumferentially from a central portion (6), wherein the upper element and the lower element (2, 3) are plate-like elements arranged substantially parallel to each other at a predetermined distance so as to provide a space therebetween, each of the upper element and the lower element (2, 3) being electrically connected at one end of the central portion (6) and electrically contacting at their respective circumferential ends to form at least a part of the enclosure (1), wherein the enclosure (1) is at least partially constructed of a conductive material, wherein at least two slots (5) extending from the central portion (6) to the peripheral edge are provided in the enclosure (1) to separate different parts of the enclosure (1), Enclosure (1).

2. The enclosure (1) according to claim 1, wherein the upper element and the lower element (2, 3) are configured to be oriented substantially perpendicular to the direction of the electric field.

3. The enclosure (1) according to claim 1 or 2, configured to enable wireless power transfer to the space.

4. The central portion (6) is divided into two parts, and an antenna feeding circuit is connected to both parts of the enclosure (1). The enclosure (1) according to claim 1 or 2.

5. The upper element (2) and the lower element (3) are connected by a connecting portion (4) at the peripheral edges of the upper element and the lower element (3), and the upper element (2), the lower element (3), and the connecting portion (4) are integrally formed. The enclosure (1) according to claim 1 or 2.

6. The enclosure (1) according to claim 1 or 2, wherein the slots (5) are provided symmetrically with respect to the central portion (6).

7. The upper element (2) and the lower element (3) forming the part of the enclosure (1) form a circular sector around the central portion (6), wherein the radius of the upper element (2) and the lower element (3) is between 5 mm and 75 mm, and / or the distance between the upper element (2) and the lower element (3) is between 5 mm and 15 mm. The enclosure (1) according to claim 1 or 2.

8. The enclosure (1) according to claim 5, wherein the upper element (2), the lower element (3), and the connecting portion (4) each include their respective thicknesses and their respective conductivities.

9. The enclosure (1) according to claim 1 or 2, wherein the space is at least partially filled with a dielectric material and an insulating material.

10. The enclosure (1) according to claim 1 or 2, wherein an opening is provided in the enclosure (1) to enable insertion of an electronic device.

11. The enclosure (1) according to claim 1 or 2, comprising a conductive layer.

12. The enclosure (1) according to claim 1 or 2, wherein the width of the slot (5) at the peripheral portion is less than 25% of the distance between the upper element (2) and the lower element (3).

13. The enclosure (1) according to claim 1 or 2, wherein the distance between the slots (5) at the peripheral portion is less than or equal to the distance between the upper element (2) and the lower element (3).

14. The enclosure (1) according to claim 1 or 2, wherein the width of the slot (5) gradually increases from the central portion (6) towards the peripheral portion.

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