Device for measuring intensity of electric current along elongate electrical conductor and method for compensating for effect of position of elongate electrical conductor on measurement

Abstract

An apparatus for measuring an intensity of an electrical current along an elongate electrical conductor and a method for compensating for an effect of a position of an elongate electrical conductor on the measurement are provided.

Description

Technical Field

[0001] The present invention relates to an apparatus for measuring the intensity of a current along a slender electrical conductor, and a method for compensating for the influence of the position of the slender electrical conductor on the measurement. Background Technology

[0002] When measuring the intensity of current along a slender conductor using a magnetic field sensor, the accuracy of the measurement depends on the position of the conductor relative to the sensor. Summary of the Invention

[0003] This invention enriches the prior art in this respect because it allows for consideration of relative positions and therefore eliminates the need for pre-defined relative positions.

[0004] The method according to the invention includes providing a magnetically permeable structure that surrounds an electrical conductor and has a cross-section having a mirror-symmetric axis, or at least a cross-section having a mirror-symmetric axis in the region surrounding the electrical conductor, wherein the longitudinal axis of the segment of the electrical conductor surrounded by the magnetically permeable structure is preferably perpendicular to the mirror-symmetric axis, and measuring the magnetic field strength at two locations offset from each other parallel to the mirror-symmetric axis, and using the magnetic field strength to compensate for the effect of the offset of the electrical conductor parallel to the mirror-symmetric axis on the measurement of the strength of the current along the electrical conductor.

[0005] The term "magnetic structure" as used herein in the specification and claims should be understood in particular as a structure made of a magnetically conductive material, such as a structure made of a ferromagnetic material like μ metal. Furthermore, the description of a magnetically conductive structure "enclosing an electrical conductor" as used in the specification and claims should be understood in particular as a magnetically conductive structure having a concave region through which the electrical conductor extends.

[0006] Furthermore, the description in the specification and claims of a magnetically conductive structure "having a mirror-symmetric axis in its cross-section at least in the region surrounding the electrical conductor" should be understood in particular as a magnetically conductive structure having a segment in its cross-section through which the electrical conductor extends and which segment is mirror-symmetric about the mirror-symmetric axis. The mirror-symmetric axis may extend (substantially) through the center of the magnetically conductive structure. The segment may be rectangular, square, elliptical, or circular. The electrical conductor may extend through the center of the segment.

[0007] Furthermore, the phrase "compensating for the effect of the offset of the conductor parallel to the mirror axis of symmetry on the measurement of the current intensity along the conductor" used in the specification and claims should be understood in particular as using a correction factor that allows the measured field strength to be mapped to, for example, the current intensity obtained through calibration measurements. Here, multiple calibration measurement sequences can be provided, each based on a different offset and each sequence including a different current intensity. By selecting the closest calibration measurement sequence, the value of the correction factor can be reduced.

[0008] The region surrounding the electrical conductor with a cross-section having a mirror-symmetric axis may include more than 50%, 75%, or 90% of the cross-sectional area of ​​the magnetically conductive structure. If the region includes 100% of the cross-sectional area of ​​the magnetically conductive structure, then the cross-section of the (entire) magnetically conductive structure has a mirror-symmetric axis.

[0009] A magnetically permeable structure can partially cover an electrical conductor.

[0010] This makes it possible to install magnetic structures without (temporarily) disconnecting the wires formed by electrical conductors.

[0011] The magnetically conductive structure can have a U-shaped cross-section.

[0012] The magnetic structure can be equipped with a housing with a V-shaped groove in its cross-section, through which an electrical conductor extends.

[0013] The V-shaped recess makes it easier to center the conductor in the magnetic structure by pressing the conductor toward the tapered end of the recess.

[0014] To create a calibration measurement sequence, an insert with one or more guides (e.g., one or more openings) can be arranged in a U-shaped or V-shaped recess, wherein the offset of an electrical conductor extending through the recess parallel (and perpendicular) to the axis of mirror symmetry can be set by the one or more guides.

[0015] This method can also measure the magnetic field strength at two locations that are mirror-symmetric about the axis of mirror symmetry, and use the magnetic field strength to compensate for the effect of the offset of the electric conductor perpendicular to the axis of mirror symmetry on the measurement.

[0016] Therefore, accurate measurements can be performed even if the electrical conductor is not centered.

[0017] The method may also include compensating for the effects of the magnetic interference field by adding the magnetic field strength at each of two locations offset from each other at a position parallel to the axis of mirror symmetry to the magnetic field strength at the respective mirror-symmetric location.

[0018] For example, two pairs of mirror-symmetrically arranged sensors can be used, and the influence of the interference field on the offset of the detected conductor from the mirror symmetry axis can be reduced by adding the magnetic field strength of each pair.

[0019] The device according to the invention includes a magnetically conductive structure surrounding an electrical conductor, and its cross-section has a mirror-symmetric axis, or its cross-section has a mirror-symmetric axis at least in the region surrounding the electrical conductor, wherein the longitudinal axis of the segment of the electrical conductor surrounded by the magnetically conductive structure is preferably perpendicular to the mirror-symmetric axis. The device also includes a first magnetic field sensor and a second magnetic field sensor, wherein these magnetic field sensors are offset from each other or arranged mirror-symmetrically about the mirror-symmetric axis.

[0020] As mentioned earlier, the measurements from these sensors can be used not only to account for the conductor's offset perpendicular to the axis of symmetry, but also to compensate for interference effects when considering the conductor's offset parallel to the axis of symmetry. It should be understood that if both offsets perpendicular to and parallel to the axis of symmetry exist, both can be considered when measuring current intensity.

[0021] The region of a cross-section with a mirror-symmetric axis surrounding an electrical conductor may include more than 50%, 75%, or 90% of the cross-sectional area of ​​the magnetically conductive structure.

[0022] A magnetically permeable structure can partially cover an electrical conductor.

[0023] The magnetically conductive structure can have a U-shaped cross-section.

[0024] The magnetic structure may be equipped with a housing having a V-shaped groove in its cross-section, through which an electrical conductor extends.

[0025] Magnetic field sensors can be designed to measure the magnetic field strength on a surface facing an electrical conductor that is perpendicular to a magnetically conductive structure.

[0026] The device may also include a third magnetic field sensor, wherein the first and second magnetic field sensors are arranged in a mirror-symmetric manner about a mirror-symmetric axis, and the third magnetic field sensor is arranged offset relative to the first magnetic field sensor, parallel to the mirror-symmetric axis.

[0027] The device may also include a fourth magnetic field sensor, wherein the third and fourth magnetic field sensors are arranged in a mirror-symmetric manner about a mirror-symmetric axis, and the fourth magnetic field sensor is arranged offset relative to the second magnetic field sensor, parallel to the mirror-symmetric axis.

[0028] The device may also include a fifth magnetic field sensor, wherein the fifth magnetic field sensor is arranged offset relative to the first and third magnetic field sensors, parallel to the axis of mirror symmetry.

[0029] The device may also include a sixth magnetic field sensor, wherein the fifth and sixth magnetic field sensors are arranged in a mirror-symmetric manner about a mirror-symmetric axis, and the sixth magnetic field sensor is arranged offset relative to the second and third magnetic field sensors, parallel to the mirror-symmetric axis.

[0030] By using paired measurements, as previously described, the effect of interference fields on the offset of the detected conductor parallel to the mirror symmetry axis can be reduced.

[0031] Furthermore, it goes without saying that the features described in conjunction with the apparatus can also be the features of the method, and vice versa. Attached Figure Description

[0032] The invention will then be described in detail with reference to the accompanying drawings, in which:

[0033] Figure 1 A schematic diagram of the apparatus according to the invention based on the first embodiment is shown;

[0034] Figure 2 A schematic diagram of the apparatus according to the invention according to a second embodiment is shown;

[0035] Figure 3 A schematic diagram of the apparatus according to the invention according to a third embodiment is shown;

[0036] Figure 4 A schematic diagram of the apparatus according to the invention based on the fourth embodiment is shown;

[0037] Figure 5 A schematic diagram of the apparatus according to the invention according to the fifth embodiment is shown;

[0038] Figure 6 A schematic diagram of the apparatus according to the invention according to the sixth embodiment is shown;

[0039] Figure 7 A flowchart illustrating a method for compensating for the effect of the position of a slender electrical conductor on the intensity of the current along the conductor as measured by a magnetic field sensor;

[0040] Figure 8 An exemplary curve is shown for determining the offset of an electrical conductor from the axis of mirror symmetry;

[0041] Figure 9 An exemplary curve is shown to compensate for the effect of the offset of the electrical conductor parallel to the mirror symmetry axis on the measurement;

[0042] Figure 10 An exemplary curve is shown for determining the transverse offset of an electrical conductor from the axis of mirror symmetry; and

[0043] Figure 11An exemplary curve is shown to compensate for the effect of the offset of the electrical conductor transverse to the mirror symmetry axis on the measurement.

[0044] Here, elements that are the same or have similar functions are identified by the same reference numerals. Detailed Implementation

[0045] Figure 1 A cross-sectional view of a device 10 according to the invention is shown. The device 10 includes a magnetically conductive structure 12. The magnetically conductive structure 12 surrounds an electrical conductor 14 having a circular cross-section. It is to be understood that the invention is not limited to a conductor 14 having a circular cross-section. For example, the conductor 14 may also have a triangular or quadrilateral cross-section.

[0046] The magnetically conductive structure 12 has a U-shaped cross-section. This U-shaped cross-section has a mirror-symmetric axis A, which is perpendicular to the longitudinal extension of the electrical conductor 14. The magnetically conductive structure 12 is also equipped with a housing 16. The cross-section of the housing 16 has a V-shaped groove through which the electrical conductor 14 extends. Thus, the electrical conductor 14 is centered relative to the legs of the magnetically conductive structure 12.

[0047] The device 10 also includes two magnetic field sensors 18 and 20, which are arranged offset from each other parallel to the mirror symmetry axis A. Here, the field strength measured in the horizontal direction by the magnetic field sensors 18 and 20 depends on the diameter of the magnetic conductor 14, thereby determining the offset of the center of the conductor 14 along the mirror symmetry axis A relative to the nearest available calibration curve. The values ​​of the calibration curve can then be used, with the aid of a correction factor, to determine the intensity of the current through the conductor 14.

[0048] like Figure 2 As shown, the groove can also be U-shaped, and the lack of a mechanism for centering the conductor 14 can be compensated by providing an additional sensor 22, in which the magnetic field sensors 20 and 22 are arranged mirror-symmetrically about the axis of mirror symmetry. This is because the field strength measured by the magnetic field sensors 20 and 22 perpendicular to the surface of the magnetically conductive structure 12 will only be equal when the electric conductor 14 extends through the axis of mirror symmetry A.

[0049] like Figure 3 and Figure 4 As shown, Figure 1 and Figure 2The illustrated device 10 may be equipped with two or one additional magnetic field sensors 22 and 24, resulting in two pairs of magnetic field sensors 18 and 20 and 24 and 22 arranged offset from each other parallel to the axis of mirror symmetry A. By using the measurements of 18 and 20 and 24 and 22 from the magnetic field sensors, as previously described, the influence of interference fields on the offset of the detection conductor 12 parallel to the axis of mirror symmetry A can be reduced.

[0050] like Figure 5 and Figure 6 As shown, additional magnetic field sensors 26 and 28 can be provided, thereby further reducing the positioning requirements of the electric conductor 14 or further improving the robustness against the influence of magnetic interference fields.

[0051] Figure 7 A flowchart of the method according to the present invention is shown. The method begins in step 30, which provides a magnetically conductive structure 12 that surrounds an electrical conductor 14, and whose cross-section perpendicular to the longitudinal direction of the electrical conductor 14 has a mirror-symmetric axis A. The method then continues in step 32, which measures the magnetic field strength at two locations offset parallel to the mirror-symmetric axis A, and uses the magnetic field strength to compensate for the effect of the offset of the electrical conductor 14 parallel to the mirror-symmetric axis A on the measurement.

[0052] exist Figure 8 In the example device 10, the relationship between the offset of the electrical conductor 14 parallel to the mirror symmetry axis A and the ratio of the magnetic field strength at two positions offset from the mirror symmetry axis A is plotted. Therefore, the offset can be determined from the ratio of the magnetic field strength at the two positions offset from the mirror symmetry axis A. Based on this offset, subsequent steps can be performed as follows: Figure 9 As shown, the correction factor is determined. By applying the correction factor to a magnetic field strength, a corrected magnetic field strength can be determined.

[0053] like Figure 10 As shown, the offset of the electric conductor 14 relative to the mirror symmetry axis A can be determined by the ratio of the magnetic field strength at two positions arranged mirror-symmetrically about the mirror symmetry axis A. Then, as... Figure 11 As shown, the magnetic field strength that will be measured when the conductor 14 is not offset relative to the mirror symmetry axis A can be inferred from the calibration curve based on the determined offset.

[0054] List of reference numerals

[0055] 10 devices

[0056] 12 structure

[0057] 14 conductors

[0058] 16-shell

[0059] 18 sensors

[0060] 20 sensors

[0061] 22 sensors

[0062] 24 sensors

[0063] 26 sensors

[0064] 28 sensors

[0065] 30 steps

[0066] 32 steps

Claims

1. A method for compensating for the influence of the position of an elongated electrical conductor (14) on the intensity of a current along the electrical conductor (14) measured by a magnetic field sensor, comprising: Provided (30) a magnetically conductive structure (12) surrounding an electrical conductor (14) and the cross-section of the magnetically conductive structure having a mirror-symmetric axis (A), or the cross-section of the magnetically conductive structure having a mirror-symmetric axis (A) at least in the region surrounding the electrical conductor (14), wherein the longitudinal axis of the segment of the electrical conductor (14) surrounded by the magnetically conductive structure (12) is preferably perpendicular to the mirror-symmetric axis (A); and The magnetic field strength (32) is measured at two locations offset from each other parallel to the mirror symmetry axis (A), and the magnetic field strength is used to compensate for the effect of the offset of the electric conductor (14) parallel to the mirror symmetry axis (A) on the measurement.

2. The method according to claim 1, wherein, The region of the cross section surrounding the electrical conductor (14) with a mirror-symmetric axis (A) includes more than 50%, more than 75%, or more than 90% of the cross-sectional area of ​​the magnetically conductive structure (12).

3. The method according to claim 1 or 2, wherein, The magnetic structure (12) only partially covers the electrical conductor (14).

4. The method according to any one of claims 1 to 3, wherein, The magnetically conductive structure (12) has a U-shaped cross-section.

5. The method according to claim 4, wherein, The magnetic structure (12) is equipped with a housing (16) having a V-shaped groove in its cross-section, and the electrical conductor (14) extends through the V-shaped groove.

6. The method according to any one of claims 1 to 5, further comprising: The magnetic field strength is measured at two locations that are mirror-symmetric about the axis of mirror symmetry (A), and the magnetic field strength is used to compensate for the effect of the offset of the electric conductor (14) perpendicular to the axis of mirror symmetry (A) on the measurement.

7. The method of claim 6, further comprising: The influence of the magnetic interference field is compensated by adding the magnetic field strength at each of the two positions offset from each other at the two positions parallel to the axis of mirror symmetry (A) to the magnetic field strength at the respective mirror symmetric position.

8. A device (10) for measuring the intensity of a current along a slender electrical conductor (14), comprising: A magnetically conductive structure (12) surrounds an electrical conductor (14), and the cross-section of the magnetically conductive structure has a mirror axis of symmetry, or the cross-section of the magnetically conductive structure has a mirror axis of symmetry (A) at least in the region surrounding the electrical conductor (14), wherein the longitudinal axis of the segment of the electrical conductor surrounded by the magnetically conductive structure (12) is preferably perpendicular to the mirror axis of symmetry; First magnetic field sensors (18, 20, 22, 26, 28); and Second magnetic field sensors (18, 20, 22, 26, 28); These magnetic field sensors (18, 20, 22, 26, 28) are offset from each other or arranged in a mirror symmetry about the axis of mirror symmetry (A).

9. The apparatus (10) according to claim 8, wherein, The region of the cross section surrounding the electrical conductor (14) with a mirror-symmetric axis (A) includes more than 50%, more than 75%, or more than 90% of the cross-sectional area of ​​the magnetically conductive structure (12).

10. The apparatus (10) according to claim 8 or 9, wherein, The magnetic structure (12) only partially covers the electrical conductor (14).

11. The apparatus (10) according to any one of claims 8 to 10, wherein, The magnetically conductive structure (12) has a U-shaped cross-section.

12. The apparatus (10) according to claim 11, wherein, The magnetic structure (12) is equipped with a housing (16) having a V-shaped groove in its cross-section, and an electrical conductor (14) extending through the V-shaped groove.

13. The apparatus (10) according to claim 11 or 12, wherein, The magnetic field sensors (18, 20, 22, 26, 28) are designed to measure the magnetic field strength on the surface of the magnetically conductive structure (12) facing the electrical conductor (14).

14. The apparatus (10) according to any one of claims 8 to 13, further comprising: Third magnetic field sensors (18, 20, 22, 26, 28); The first magnetic field sensor (18, 20, 22, 26, 28) and the second magnetic field sensor (18, 20, 22, 26, 28) are arranged symmetrically about the mirror symmetry axis (A); and The third magnetic field sensor (18, 20, 22, 26, 28) is arranged offset relative to the first magnetic field sensor (18, 20, 22, 26, 28) along the mirror symmetry axis (A).

15. The apparatus (10) according to claim 14, further comprising: Fourth magnetic field sensor (18, 20, 22, 26, 28); The third magnetic field sensor (18, 20, 22, 26, 28) and the fourth magnetic field sensor (18, 20, 22, 26, 28) are arranged symmetrically about the mirror symmetry axis (A); and The fourth magnetic field sensor (18, 20, 22, 26, 28) is arranged offset relative to the second magnetic field sensor (18, 20, 22, 26, 28) along the mirror symmetry axis (A).

16. The apparatus (10) according to claim 15, further comprising: Fifth magnetic field sensor (18, 20, 22, 26, 28); The fifth magnetic field sensor (18, 20, 22, 26, 28) is arranged offset relative to the first and third magnetic field sensors (18, 20, 22, 26, 28) along the mirror symmetry axis (A).

17. The apparatus (10) according to claim 16, further comprising: The sixth magnetic field sensor (18, 20, 22, 26, 28); The fifth magnetic field sensor (18, 20, 22, 26, 28) and the sixth magnetic field sensor (18, 20, 22, 26, 28) are arranged symmetrically about the mirror symmetry axis (A); and The sixth magnetic field sensor (18, 20, 22, 26, 28) is arranged offset relative to the second and third magnetic field sensors (18, 20, 22, 26, 28) along the mirror symmetry axis (A).

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