Shielding component and current-measuring device

Abstract

The invention relates to a shielding component for magnetically shielding at least one contactless current sensor of a current-measuring device from external magnetic fields, the shielding component having a casing and a receiving space located within the casing for receiving the at least one contactless current sensor, and the receiving space being enclosed by the casing. The invention also relates to a current-measuring device for contactless current measurement in an electrical conductor, which device comprises a shielding component of this kind.

Description

[0001] Shielding component and current measuring device

[0002] The invention relates to a shielding component for the magnetic shielding of at least one non-contact current sensor of a current measuring device from external magnetic fields, wherein the shielding component has a sheath and a receiving space arranged within the sheath for receiving the at least one non-contact current sensor, the receiving space being enclosed by the sheath. The invention further relates to a current measuring device for non-contact current measurement in an electrical conductor, which has such a shielding component.

[0003] In general terms, the invention relates to the field of non-contact current measurement on electrical conductors, e.g., for direct current measurement. Certain requirements regarding the measurement accuracy of the current measurement are to be met, in particular normative requirements, e.g., according to calibration law, are to be fulfilled. Specifically, current measurement according to DIN EN 50470-4 should be possible, e.g., for use in calibrated electric vehicle charging stations.

[0004] According to the state of the art, resistance-based measurement methods are most commonly used for measuring direct currents up to 1500 amperes for billing purposes. In resistance-based measurement methods, the voltage drop across a defined resistor caused by the current being measured is measured. As an alternative to resistance-based measurement methods, direct currents can also be detected by indirect measurement methods via the measurement of magnetic flux density. However, these measurement methods are sensitive to external magnetic interference. The invention is based on the objective of providing devices for improved, interference-resistant current measurement in magnetic field-based measurement methods.

[0005] This task is accomplished with a shielding component of the type mentioned above by constructing the sheath in multiple layers, consisting of at least two material layers arranged radially one behind the other. These layers comprise a first material layer made of a first material and a second material layer made of a second material that differs from the first material in terms of permeability and / or saturation flux density. Such a multilayered design of the sheath, with first and second material layers exhibiting different permeabilities and / or saturation flux density, enables particularly efficient shielding of a magnetic field-based sensor located within the shielding component against external interference fields.In particular, this combination of material layers makes it possible to perform current measurements over a wide current range with the same current measuring device, especially from currents in the range of a few amperes up to several hundred amperes or over 1000 amperes. The proposed shielding component ensures particularly efficient shielding against external interference fields over such a wide current measuring range.

[0006] The shielding component according to the invention can be used, in particular, to implement a current measuring device for direct current measurement, especially for high currents up to and exceeding 100 amperes. It is particularly possible to implement a calibrated current measuring device that complies with the requirements of calibration law and is thus suitable for electric vehicle charging stations.

[0007] As mentioned, the recording space is enclosed by the casing. The casing can be designed as a completely or at least predominantly closed casing.

[0008] According to an advantageous embodiment of the invention, the first material layer is predominantly or entirely composed of a highly permeable first material. Such a highly permeable first material allows for particularly effective minimization of the magnetic flux density of externally acting magnetic fields within the shielding component, i.e., in the receiving area. The highly permeable first material can, for example, have a permeability of at least 80,000. The highly permeable first material can be a soft magnetic material, such as a soft magnetic nickel-iron alloy like Mu-metal or Permenorm. According to an advantageous embodiment of the invention, the second material layer is predominantly or entirely composed of a second material that has a higher saturation flux density and lower permeability than the first material.It was found that at higher measured currents, particularly above 100 amperes, the first highly permeable material layer saturates and then no longer provides sufficient protection against external magnetic interference. To compensate for this effect, a second material layer made of a material with a higher saturation flux density and lower permeability than the first material is proposed. This second material layer therefore provides protection against external interference at higher currents. The second material can, for example, have a saturation flux density of at least 1.2 T or at least 1.8 T and a permeability of at most 50,000. The second material can, for example, be soft iron.

[0009] Since both properties of the first and second materials are not found combined in a single material, it is accordingly proposed according to the invention to integrate these two materials into the first and second material layers respectively.

[0010] According to an advantageous embodiment of the invention, the first material layer forms an outer layer of the multilayered structure of the screen component, within which the second material layer is arranged. In other words, the second material layer is thus predominantly or completely surrounded by the first material layer. This minimizes any disruptive influence of residual material in the outer layers on the receiving space.

[0011] According to an advantageous embodiment of the invention, the second material layer is spaced radially apart from the first material layer. Accordingly, a radial gap is created between the first and second material layers, which can be used to introduce additional material to further improve the shielding effect of the shielding component.

[0012] According to an advantageous embodiment of the invention, a first gap formed by the radial distance between the first and second material layers is at least predominantly filled by a first filling material. The first filling material can be a diamagnetic material, e.g., a plastic material. The first filling material can fill the gap completely or only partially.

[0013] If the space between the first and second material layers is not filled by a first filler material, one or more spacers can be arranged in the space to ensure a defined positioning and spacing of the second material layer within the first material layer.

[0014] According to an advantageous embodiment of the invention, the sheath has at least a third material layer, which is circumferentially surrounded by the second material layer and is made of a magnetic field-shielding material. In this way, the shielding effect of the shielding component can be further improved.

[0015] According to an advantageous embodiment of the invention, the third material layer is radially spaced from the second material layer. Accordingly, a further radial gap is created, in this case between the second and third material layers. This gap can then be filled with a suitable filler material to further improve the shielding effect of the shielding component.

[0016] According to an advantageous embodiment of the invention, a second gap formed by the radial distance between the third and second material layers is at least predominantly filled with a second filling material. This second filling material can be identical to the first or different. In particular, the shielding effect of the shielding component can be significantly improved by using different first and second filling materials. For example, the second filling material can be a paramagnetic material, such as a gas, e.g., air. Introducing such an air-based material can compress the hysteresis curve and thus further increase the shielding effect.

[0017] To ensure the correct positioning of the third material layer within the second, additional spacers can be installed in the second gap. These spacers ensure a defined positioning and spacing of the third material layer within the second. A large number of such material transitions between the individual material layers, as well as in the gaps or with the filling materials, can advantageously deflect interfering magnetic fields and thus minimize their effects in the receiving space within the shielding component.

[0018] According to an advantageous embodiment of the invention, the shielding component has a through-opening at each of its opposite ends for guiding through the at least one current sensor and / or an electrical conductor in which the current is to be measured. Accordingly, the shielding component is designed to be open at its ends so that the current measuring device and / or the electrical conductor in which the current is to be measured can be easily inserted. For example, the shielding component can be designed like a section of pipe.

[0019] According to an advantageous embodiment of the invention, the sheath has a hollow cylindrical or other rotationally symmetrical shape. This allows the shielding effect of the shielding component to be further optimized. In an advantageous embodiment, the receiving chamber can be arranged precisely in the center of the shielding component, which further improves the shielding effect.

[0020] According to an advantageous embodiment of the invention, the material layers of the sheath are arranged concentrically to one another. This further improves the shielding effect.

[0021] The sheath, with its multi-layered structure, can be supplied as a complete, single-piece unit. Alternatively, the sheath can be made up of multiple parts that the user can assemble. For example, the sheath could consist of two half-shells that are then applied around the non-contact current sensors and the electrical conductor in which the current is to be measured.

[0022] The aforementioned problem is also solved by a current measuring device for non-contact current measurement in an electrical conductor, which is to be guided through a conductor receiving chamber of the current measuring device, wherein the current measuring device has at least one non-contact current sensor, in particular a TMR sensor or other magnetoresistive sensor, e.g., an AMR or GMR sensor, and a shielding component of the type described above, in whose receiving chamber the at least one current sensor is arranged. The advantages described above can also be realized in this way. Advantageously, the conductor receiving chamber can be arranged exactly in the center of the shielding component.

[0023] According to an advantageous embodiment of the invention, the current measuring device has at least two spaced-apart non-contact current sensors configured for differential current sensing in an electrical conductor passing through a gap between the sensors. The non-contact current sensors can, in particular, always be arranged in pairs in a differential configuration. Such a pair of non-contact current sensors can then be positioned, in particular, on opposite sides of an electrical conductor in which the current is to be measured. This further improves the measurement accuracy of the current measuring device, since homogeneous external interference fields can be almost completely eliminated computationally by evaluating the sensor signals through the differential configuration.

[0024] According to an advantageous embodiment of the invention, the current measuring device has an electrical conductor for conducting the current to be detected by the current measuring device, wherein the electrical conductor is arranged in the conductor receiving chamber of the current measuring device and has connections for connecting to external electrical lines. This has the advantage that the current measuring device can be provided as a fully designed, ready-to-install component, which the user simply needs to connect to the external electrical lines, for example in an electric vehicle charging station, using the connections.

[0025] The electrical conductor for conveying the current to be detected by the current measuring device can be designed as a relatively robust current-carrying structure, particularly with relatively low ohmic resistance. The electrical conductor can be designed as a current-carrying rod or current-carrying beam. At least in the area of ​​the conductor receiving chamber, the electrical conductor can have a round, particularly circular, or rectangular cross-section, for example, a rectangular or square cross-section. The electrical conductor can have the same cross-sectional shape throughout its length or a varying cross-sectional shape.For example, the electrical conductor may have a different cross-sectional shape in areas outside the conductor receiving chamber than within the conductor receiving chamber, for example, to provide an electrical and mechanical interface for the easy connection of external electrical components. According to an advantageous embodiment of the invention, the current measuring device includes evaluation electronics that are configured to evaluate the signals from the at least one non-contact current sensor and to determine the current flowing through the electrical conductor.

[0026] The invention is explained in more detail below with reference to exemplary embodiments and drawings.

[0027] They show

[0028] Figure 1 shows a current measuring device in perspective view, Figure 2 shows a current measuring device in top view.

[0029] The current measuring device 13 shown in Figure 1 has a shielding component 4 for magnetically shielding at least a part of the current measuring device 13, in particular magnetic field-sensitive non-contact current sensors, from external magnetic fields. The shielding component 4 has a sheath 14 in which a receiving chamber 5 for receiving the at least one non-contact current sensor is located. An electrical conductor 11, in which the current is to be measured, can also be arranged in or passed through the receiving chamber 5. For example, the electrical conductor 11 can be provided as a fixed component of the current measuring device 13, which the user only needs to connect to current-carrying lines via terminals 12 of the electrical conductor 11.

[0030] The sheath 14 can have a multilayered structure consisting of several material layers, e.g., a first material layer 1, a second material layer 2 arranged therein, and a third material layer 3 arranged therein. A radial first gap 10 can be formed between the first and second material layers 1, 2, and a radial second gap 20 can be formed between the second and third material layers 2, 3. These gaps 10, 20 can be filled with filler materials, e.g., as described below with reference to Figure 2.

[0031] Figure 2 illustrates that the first gap 10 is filled with a first filling material, e.g., a diamagnetic material such as a plastic. The second gap 20 can be filled, for example, with air or another paramagnetic material. In order to establish a stable mechanical connection between the second material layer 2 and the third material layer 3, these material layers can be held in a defined position relative to each other by means of spacers 9, e.g., such that the first, second, and third material layers 1, 2, 3 are arranged concentrically to each other.

[0032] The electrical conductor 11 arranged in the receiving space 5 can, for example, also be positioned at a desired position, in particular exactly in the center of the receiving space 5, by means of spacers 8. One or more pairs of differentially operated non-contact current sensors 6, 7 can be arranged on the electrical conductor 11.

[0033] Alternatively, the current measuring device 13 shown in Figure 2 can also be provided without the electrical conductor 11, e.g., in applications where the user wishes to insert and route an electrical conductor through it. In this case, a sleeve 15 can be arranged in the receiving chamber 5, which has a suitable shape to accommodate the user-specific electrical conductor. The current sensors 6, 7 can then be attached to the sleeve 15.

[0034] Reference symbol list

[0035] 1 first matenal layer

[0036] 2 second layer of material

[0037] 3 third layer of material

[0038] 4. Shield component

[0039] 5 Recording room

[0040] 6 Current sensor

[0041] 7 Current sensor

[0042] 8 spacers

[0043] 9 spacers

[0044] 10 first space

[0045] 11 electrical conductor

[0046] 12 connections

[0047] 13 Current measuring device

[0048] 14 coat

[0049] 15 sleeve

[0050] 20 second space

Claims

Patent claims:

1. Shielding component (4) for magnetically shielding at least one non-contact current sensor (6, 7) of a current measuring device (13) from external magnetic fields, wherein the shielding component (4) has a sheath (14) and a receiving space (5) arranged within the sheath (14) for receiving the at least one non-contact current sensor (6, 7), wherein the receiving space (5) is enclosed by the sheath (14), characterized in that the sheath (14) is composed of multiple layers of at least two material layers (1, 2, 3) arranged one behind the other in a radial direction, comprising a first material layer (1) of a first material and a second material layer (2) of a second material which differs from the first material with respect to permeability and / or saturation flux density.

2. Shielding component according to claim 1, characterized in that the first material layer (1) is predominantly or completely made of a highly permeable first material.

3. Shielding component according to one of the preceding claims, characterized in that the second material layer (2) is predominantly or completely made of a second material which has a higher saturation flux density and lower permeability than the first material.

4. Shield component according to one of the preceding claims, characterized in that the first material layer (1) forms an outer material layer of the multi-layered structure of the shield component (4), within which the second material layer (2) is arranged.

5. Shielding component according to one of the preceding claims, characterized in that the second material layer (2) is radially separated from the first material layer. (1) is spaced apart.

6. Shield component according to claim 5, characterized in that a radial distance between the first material layer (1) and the second material layer (2) the first gap formed (10) is at least predominantly filled by a first filling material.

7. Shielding component according to one of the preceding claims, characterized in that the sheath (14) has at least a third material layer (3) which is circumferentially surrounded by the second material layer (2) and is formed from a magnetic field shielding material.

8. Shield component according to claim 7, characterized in that the third material layer (3) is spaced apart in the radial direction from the second material layer (2).

9. Shield component according to claim 8, characterized in that a second space (20) formed by the radial distance between the third material layer (3) and the second material layer (2) is at least predominantly filled by a second filling material.

10. Shielding component according to one of the preceding claims, characterized in that the shielding component (40) has a through-opening at opposite end sides for passing through the at least one current sensor (6, 7) and / or an electrical conductor in which the current is to be measured.

11. Shield component according to one of the preceding claims, characterized in that the sheath (14) has a hollow cylindrical or other rotationally symmetrical shape.

12. Shield component according to one of the preceding claims, characterized in that the material layers of the sheath (14) are arranged concentrically to each other.

13. Current measuring device (13) for non-contact current measurement in an electrical conductor, which is connected by a conductor receiving chamber (15) of the current measuring device (13) is to be passed through, wherein the current measuring device has at least one non-contact current sensor (6, 7), in particular a TMR sensor or other magnetoresistive sensor, and a screen component (4) according to one of the preceding claims, in whose receiving space (5) the at least one current sensor (6, 7) is arranged.

14. Current measuring device according to claim 13, characterized in that the current measuring device (13) has at least two spaced-apart non-contact current sensors (6, 7) which are arranged for differential current sensing in an electrical conductor passed through a space between the current sensors (6, 7).

15. Current measuring device according to one of claims 13 to 14, characterized in that the current measuring device (13) has an electrical conductor (11) for passing through the current to be detected by means of the current measuring device (13), wherein the electrical conductor (11) is arranged in the conductor receiving chamber (15) of the current measuring device (13) and has connections (12) for connecting to external electrical conductors. *****

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