DEVICE FOR MEASURING THE INTENTION OF A CURRENT FLOW ALONG AN EARLY ELECTRIC CONDUCTOR AND METHOD FOR COMPENSATING FOR THE INFLUENCE OF THE POSITION OF THE EARLY ELECTRIC CONDUCTOR ON THE MEASUREMENT

Abstract

The present invention provides a device for measuring an intensity of a current flow along an elongate electric conductor, and a method for compensating an influence of a position of the elongate electric conductor on the measurement.

Description

[0001] Device for measuring the intensity of a current flow along an elongated electrical conductor and method for compensating for the influence of a position of the elongated electrical conductor on the measurement

[0002] AREA

[0003] The present invention relates to a device for measuring a strength of a current flow along an elongated electrical conductor and a method for compensating for an influence of a position of the elongated electrical conductor on the measurement.

[0004] BACKGROUND

[0005] When measuring the strength of a current flow along an elongated electrical conductor using a magnetic field sensor, the accuracy of the measurement result depends on the position of the electrical conductor relative to the sensor.

[0006] PRESENTATION OF THE INVENTION

[0007] The present invention enriches the state of the art in this regard as it allows the relative position to be taken into account and thus does not require a predetermined relative position.

[0008] A method according to the invention comprises providing a magnetically permeable structure which surrounds the electrical conductor and whose cross section has a mirror-like axis of symmetry or whose cross section has a mirror-like axis of symmetry at least in a region around the electrical conductor, wherein a longitudinal axis of a section of the electrical conductor surrounded by the permeable structure is preferably perpendicular to the mirror-like axis of symmetry, and measuring magnetic field strengths at two positions offset from one another parallel to the mirror-like axis of symmetry and using the magnetic field strengths to compensate for the influence of an offset of the electrical conductor parallel to the mirror-like axis of symmetry on the measurement of the strength of the current flow along the electrical conductor. The term "magnetically permeable structure," as used in the description and claims, is to be understood in particular as a structure made of a magnetically permeable material.For example, a structure made of a ferromagnetic material such as a mu-metal. Furthermore, a magnetically permeable structure "surrounding the electrical conductor," as used in the description and claims, is understood to mean, in particular, a magnetically permeable structure having a concave region through which the electrical conductor extends.

[0009] Furthermore, a magnetically permeable structure "whose cross-section has a mirror-like axis of symmetry at least in a region around the electrical conductor," as used in the description and claims, is understood to mean, in particular, a magnetically permeable structure whose cross-section has a section through which the electrical conductor extends and which is mirror-symmetrical to a mirror-like axis of symmetry. The mirror-like axis of symmetry can run (essentially) through a center of the magnetically permeable structure. The section can be rectangular, square, oval, or circular. The electrical conductor can extend through a center of the section.

[0010] Furthermore, the phrase "compensating for the influence of an offset of the electrical conductor parallel to the mirror symmetry axis on a measurement of the strength of the current flow along the electrical conductor," as used in the description and claims, is understood to mean, in particular, the use of a correction factor that allows measured field strengths to be mapped to current strengths obtained, for example, through calibration measurements. Several calibration measurement series can be provided, each series based on a different offset and each series comprising different current strengths. By selecting the closest calibration measurement series, the magnitude of the correction factor can be reduced.

[0011] The area of ​​the cross-section around the electrical conductor that has a mirror symmetry axis can comprise more than 50%, more than 75%, or more than 90% of the cross-sectional area of ​​the magnetically permeable structure. If the area comprises 100% of the cross-sectional area of ​​the magnetically permeable structure, the cross-section of the (entire) magnetically permeable structure has a mirror symmetry axis.

[0012] The magnetically permeable structure can only partially encompass the electrical conductor. This allows the permeable structure to be attached without (temporarily) disrupting the electrical connection formed by the electrical conductor.

[0013] The magnetically permeable structure may have a U-shaped cross-section.

[0014] The magnetically permeable structure may be provided with a housing whose cross-section has a V-shaped recess, wherein the electrical conductor extends through the V-shaped recess.

[0015] A V-shaped cutout can facilitate centering of the electrical conductor in the magnetically permeable structure by pushing the electrical conductor toward the tapered end of the cutout.

[0016] To produce the calibration measurement series, an insert with one or more guides (e.g. one or more openings) can be arranged in the U-shaped or V-shaped cutout, wherein an offset of an electrical conductor extending through the cutout parallel (and perpendicular) to the mirror symmetry axis can be specified by the one or more guides.

[0017] The method may further comprise measuring magnetic field strengths at two positions mirror-symmetrical to the mirror symmetry axis and using the magnetic field strengths to compensate for the influence of an offset of the electrical conductor perpendicular to the mirror symmetry axis on the measurement.

[0018] This allows an accurate measurement to be carried out even without centering the electrical conductor.

[0019] The method may further comprise compensating for the influence of magnetic interference fields by adding each of the magnetic field strengths at the two positions offset from each other parallel to the mirror symmetry axis with a magnetic field strength at the respective mirror-symmetric position.

[0020] For example, two pairs of mirror-symmetrically arranged sensors can be provided, and by adding the magnetic field strengths per pair, the influence of interference fields on the detection of the offset of the electrical conductor parallel to the mirror symmetry axis can be reduced. A device according to the invention comprises a magnetically permeable structure which surrounds the electrical conductor and whose cross-section has a mirror symmetry axis or whose cross-section has a mirror symmetry axis at least in a region around the electrical conductor, wherein a longitudinal axis of a section of the electrical conductor surrounded by the permeable structure is preferably perpendicular to the mirror symmetry axis, a first magnetic field sensor, and a second magnetic field sensor, wherein the magnetic field sensors are offset from one another parallel to the mirror symmetry axis or arranged mirror-symmetrically to the mirror symmetry axis.

[0021] As already explained, the measured values ​​of these sensors can be used not only to account for an offset of the electrical conductor perpendicular to the axis of symmetry, but also to compensate for interference when considering the offset of the electrical conductor parallel to the axis of symmetry. It should be understood that if an offset perpendicular to the axis of symmetry and an offset parallel to the axis of symmetry exist, both can be taken into account when measuring the current.

[0022] The area of ​​the cross-section around the electrical conductor having a mirror symmetry axis may comprise more than 50%, more than 75% or more than 90% of a cross-sectional area of ​​the magnetically permeable structure.

[0023] The magnetically permeable structure can only partially encompass the electrical conductor.

[0024] The magnetically permeable structure may have a U-shaped cross-section.

[0025] The magnetically permeable structure may be provided with a housing whose cross-section has a V-shaped recess, wherein the electrical conductor extends through the V-shaped recess.

[0026] The magnetic field sensors can be configured to measure a magnetic field strength perpendicular to a surface of the magnetically permeable structure facing the electrical conductor.

[0027] The device may further comprise a third magnetic field sensor, wherein the first magnetic field sensor and the second magnetic field sensor are arranged mirror-symmetrically to the mirror axis of symmetry, and the third magnetic field sensor is arranged offset relative to the first magnetic field sensor parallel to the mirror axis of symmetry. The device may further comprise a fourth magnetic field sensor, wherein the third magnetic field sensor and the fourth magnetic field sensor are arranged mirror-symmetrically to the mirror axis of symmetry, and the fourth magnetic field sensor is arranged offset relative to the second magnetic field sensor parallel to the mirror axis of symmetry.

[0028] The device may further comprise 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 mirror symmetry axis.

[0029] The device may further comprise a sixth magnetic field sensor, wherein the fifth magnetic field sensor and the sixth magnetic field sensor are arranged mirror-symmetrically to the mirror symmetry axis and the sixth magnetic field sensor is arranged offset relative to the second and third magnetic field sensors parallel to the mirror symmetry axis.

[0030] By using the measured values ​​of the pairs, as already explained, the influence of interference fields on the detection of the displacement of the electrical conductor parallel to the mirror symmetry axis can be reduced.

[0031] Furthermore, it is understood that the features described in connection with the device can also be features of the method and vice versa.

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is explained below in the detailed description using exemplary embodiments, with reference to drawings in which:

[0034] Fig. 1 is a schematic representation of a device according to the invention according to a first embodiment;

[0035] Fig. 2 is a schematic representation of a device according to the invention according to a second embodiment;

[0036] Fig. 3 is a schematic representation of a device according to the invention according to a third embodiment; Fig. 4 is a schematic representation of a device according to the invention according to a fourth embodiment;

[0037] Fig. 5 is a schematic representation of a device according to the invention according to a fifth embodiment;

[0038] Fig. 6 is a schematic representation of a device according to the invention according to a sixth embodiment;

[0039] Fig. 7 is a flowchart of a method for compensating for an influence of a position of an elongated electrical conductor on a measurement of a strength of a current flow along the electrical conductor by a magnetic field sensor;

[0040] Fig. 8 shows an exemplary curve for determining an offset of the electrical conductor parallel to the mirror symmetry axis;

[0041] Fig. 9 shows an exemplary curve for compensating the influence of the offset of the electrical conductor parallel to the mirror symmetry axis on the measurement;

[0042] Fig. io shows an exemplary curve for determining an offset of the electrical conductor transverse to the mirror symmetry axis; and

[0043] Fig. ii shows an exemplary curve for compensating the influence of the offset of the electrical conductor transverse to the mirror symmetry axis on the measurement.

[0044] In the drawings, identical or functionally similar elements are identified by the same reference symbols.

[0045] WAYS OF IMPLEMENTING THE INVENTION

[0046] Fig. 1 shows a cross-sectional view of a device 10 according to the invention. The device 10 comprises a magnetically permeable structure 12. The magnetically permeable structure 12 surrounds an electrical conductor 14 having a circular cross-section. It should be understood that the invention is not limited to conductors 14 with circular cross-sections. For example, the conductor 14 could also have a triangular or quadrangular cross-section.

[0047] The magnetically permeable structure 12 has a U-shaped cross-section. The U-shaped cross-section has a mirror symmetry axis A, which runs perpendicular to the longitudinal direction of the electrical conductor 14. The magnetically permeable structure 12 is further provided with a housing 16. The cross-section of the housing 16 has a V-shaped recess through which the electrical conductor 14 extends. This centers the electrical conductor 14 relative to the legs of the permeable structure 12.

[0048] The device 10 further comprises two magnetic field sensors 18 and 20, which are arranged offset from one another parallel to the mirror symmetry axis A. The field strength measured by the magnetic field sensors 18 and 20 in the horizontal direction depends on the diameter of the magnetic conductor 14, whereby the offset of the center of the electrical conductor 14 along the mirror symmetry axis A can be determined relative to the offset on which the nearest available calibration curve is based. The values ​​of the calibration curve can then be used, using a correction factor, to determine the strength of the current flow through the conductor 14.

[0049] As indicated in Fig. 2, the recess can also be U-shaped, and the lack of a device for centering the conductor 14 can be compensated for by providing an additional sensor 22 by arranging the magnetic field sensors 20 and 22 mirror-symmetrically to the mirror symmetry axis. This is because the field strengths measured by the magnetic field sensors 20 and 22 perpendicular to the surface of the magnetically permeable structure 12 are only equal when the electrical conductor 14 extends through the mirror symmetry axis A.

[0050] As shown in Fig. 3 and Fig. 4, the devices 10 shown in Fig. 1 and Fig. 2 can be provided with two or one further magnetic field sensors 22 and 24, resulting in two pairs of magnetic field sensors 18 and 20 or 24 and 22 arranged offset from one another parallel to the mirror symmetry axis, the magnetic field sensors 18 and 20 or 24 and 22 being arranged mirror-symmetrically to the mirror symmetry axis A. By using the measured values ​​of the magnetic field sensor pairs 18 and 20 or 24 and 22, as already explained, the influence of interference fields on the detection of the offset of the electrical conductor 12 parallel to the mirror symmetry axis A can be reduced.

[0051] As shown in Fig. 5 and Fig. 6, further magnetic field sensors 26 and 28 can be provided, whereby the requirements for the positioning of the electrical conductor 14 can be further reduced or the robustness against the influence of magnetic interference fields can be further increased.

[0052] Fig. 7 shows a flowchart of the method according to the invention. This begins in step 30 with the provision of the magnetically permeable structure 12, which surrounds the electrical conductor 14 and whose cross-section has the mirror symmetry axis A perpendicular to the longitudinal direction of the electrical conductor 14. The method then continues in step 32 with the measurement of magnetic field strengths at two positions offset parallel to the mirror symmetry axis A and the use of the magnetic field strengths to compensate for the influence of an offset of the electrical conductor 14 parallel to the mirror symmetry axis A on the measurement.

[0053] In Fig. 8, the offset of the electrical conductor 14 parallel to the mirror symmetry axis A is plotted against the ratio of the magnetic field strength at two positions offset parallel to the mirror symmetry axis A for an exemplary device 10. The offset can thus be determined from the ratio of the magnetic field strength at the two positions offset parallel to the mirror symmetry axis A. Based on the offset, a correction factor can then be determined, as shown in Fig. 9. By applying the correction factor to one of the magnetic field strengths, a corrected magnetic field strength can then be determined.

[0054] As shown in Fig. 10, an offset of the electrical conductor 14 relative to the mirror symmetry axis A can be determined from the ratio of the magnetic field strength at two positions arranged mirror-symmetrically relative to the mirror symmetry axis A. From the determined offset, as illustrated in Fig. 11, a calibration curve can then be used to determine the magnetic field strength that would be measured if the electrical conductor 14 were not offset relative to the mirror symmetry axis A. LIST OF REFERENCE SYMBOLS

[0055] 10 Device

[0056] 12 Structure

[0057] 14 ladders

[0058] 16 housings

[0059] 18 Sensor

[0060] 20 sensors

[0061] 22 Sensor

[0062] 24 sensors

[0063] 26 Sensor

[0064] 28 Sensor

[0065] 30 steps

[0066] 32 steps

Claims

CLAIMS 1. A method for compensating for an influence of a position of an elongated electrical conductor (14) on a measurement of a strength of a current flow along the electrical conductor (14) by a magnetic field sensor, comprising: Providing (30) a magnetically permeable structure (12) which surrounds the electrical conductor (14) and whose cross section has a mirror symmetry axis (A) or whose cross section has a mirror symmetry axis (A) at least in a region around the electrical conductor (14), wherein a longitudinal axis of a section of the electrical conductor (14) surrounded by the magnetically permeable structure (12) is preferably perpendicular to the mirror symmetry axis (A); and Measuring (32) magnetic field strengths at two positions offset from one another parallel to the mirror symmetry axis (A) and using the magnetic field strengths to compensate for the influence of an offset of the electrical 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 around the electrical conductor (14) having a mirror symmetry axis (A) comprises more than 50%, more than 75% or more than 90% of a cross-sectional area of ​​the magnetically permeable structure (12).

3. Method according to claim 1 or 2, wherein the magnetically permeable structure (12) only partially encompasses the electrical conductor (14).

4. Method according to one of claims 1 to 3, wherein the magnetically permeable structure (12) has a U-shaped cross-section. 5- Method according to claim 4, wherein the magnetically permeable structure (12) is provided with a housing (16) whose cross section has a V-shaped recess, and the electrical conductor (14) extends through the V-shaped recess.

6. The method according to any one of claims 1 to 5, further comprising: Measuring magnetic field strengths at two positions mirror-symmetrical to the mirror symmetry axis (A) and using the magnetic field strengths to compensate for the influence of an offset of the electrical conductor (14) perpendicular to the mirror symmetry axis (A) on the measurement.

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

8. A device (10) for measuring the strength of a current flow along an elongated electrical conductor (14), comprising: a magnetically permeable structure (12) which surrounds the electrical conductor (14) and whose cross section has a mirror axis of symmetry or whose cross section has a mirror axis of symmetry (A) at least in a region around the electrical conductor (14), wherein a longitudinal axis of a section of the electrical conductor surrounded by the permeable structure (12) is preferably perpendicular to the mirror axis of symmetry; a first magnetic field sensor (18, 20, 22, 26, 28); and a second magnetic field sensor (18, 20, 22, 26, 28); wherein the magnetic field sensors (18, 20, 22, 26, 28) are arranged offset from one another parallel to the mirror axis of symmetry (A) or mirror-symmetrically to the mirror axis of symmetry (A). 9- Device (10) according to claim 8, wherein the area of ​​the cross section around the electrical conductor (14) having a mirror symmetry axis (A) comprises more than 50%, more than 75% or more than 90% of a cross-sectional area of ​​the magnetically permeable structure (12).

10. Device (10) according to claim 8 or 9, wherein the magnetically permeable structure (12) only partially surrounds the electrical conductor (14).

11. Device (10) according to one of claims 8 to 10, wherein the magnetically permeable structure (12) has a U-shaped cross-section.

12. Device (10) according to claim 11, wherein the magnetically permeable structure (12) is provided with a housing (16) whose cross section has a V-shaped recess, and the electrical conductor (14) extends through the V-shaped recess.

13. Device (10) according to claim 11 or 12, wherein the magnetic field sensors (18, 20, 22, 26, 28) are arranged to measure a magnetic field strength perpendicular to a surface of the magnetically permeable structure (12) facing the electrical conductor (14).

14. Device (10) according to one of claims 8 to 13, further comprising: a third magnetic field sensor (18, 20, 22, 26, 28); wherein the first magnetic field sensor (18, 20, 22, 26, 28) and the second magnetic field sensor (18, 20, 22, 26, 28) are arranged mirror-symmetrically to the mirror symmetry axis (A); and wherein 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) parallel to the mirror symmetry axis (A). 15- Device (10) according to claim 14, further comprising: a fourth magnetic field sensor (18, 20, 22, 26, 28); wherein the third magnetic field sensor (18, 20, 22, 26, 28) and the fourth magnetic field sensor (18, 20, 22, 26, 28) are arranged mirror-symmetrically to the mirror symmetry axis (A); and wherein 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) parallel to the mirror symmetry axis (A).

16. The device (10) of claim 15, further comprising: a fifth magnetic field sensor (18, 20, 22, 26, 28); wherein the fifth magnetic field sensor (18, 20, 22, 26, 28) is offset relative to the first and third magnetic field sensors (18, 20, 22, 26, 28) parallel to the mirror symmetry axis (A).

17. The device (10) according to claim 16, further comprising: a sixth magnetic field sensor (18, 20, 22, 26, 28); wherein the fifth magnetic field sensor (18, 20, 22, 26, 28) and the sixth magnetic field sensor (18, 20, 22, 26, 28) are arranged mirror-symmetrically to the mirror symmetry axis (A); and wherein 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) parallel to the mirror symmetry axis (A).