Method for current measurement by proportional magnetic field measurements in current carrying conductors

Abstract

Method for measuring a current applied to an electrical conductor. At least one non-conductive region is inserted in the conductor, separating the conductor in a main current path and at least one sense current path. The sense current path carries a proportion of the total current applied to the electrical conductor. A magnetic field sensor senses a magnetic field in the area of the sense current path.

Description

[0001] Methode Electronics Malta Ltd. 26154 / 23

[0002] Method for current measurement by proportional magnetic field measurements in current carrying conductors

[0003] Technical field

[0004] The present disclosure refers to a method for measuring a current applied to an electrical conductor .

[0005] Background art

[0006] US 2021 / 0048454 Al discloses an integrated current-measuring apparatus including a printed circuit board . The printed circuit board is designed as a shunt resistor . It includes a resistive element which has a present resistance and terminals extending from both sides of the resistive element . The resistor is attached to a bottom surface of the printed circuit board . A hall sensor is mounted on a top surface of the printed circuit board to face the shunt resistor with the printed circuit board being imposed between the hall sensor and the shunt resistor .

[0007] The measurement of current in electrical devices is commonly done to measure a load and / or a performance of a device .

[0008] Such a measurement may be performed directly in an electronic appliance by using sense resistors .

[0009] However , as current values rise , the sense resistors tend not to provide the required galvanic isolation needed for a number of safety requirements .

[0010] The current may instead be measured indirectly . The indirect measurement can be done by sensing a magnetic field of a current carrying conductor .

[0011] An indirect measurement of the current includes sensing the magnetic field of the current carrying conductor . The indirect measurement is particularly useful if high current values are present and a good isolation is required .

[0012] A magnetic field produced by the current carrying conductor can be measured in a variety of different ways . Methode Electronics Malta Ltd, 26154 / 23

[0013] However, cases occur , in which the high magnetic field exceeds a given limit of the magnetic sensing element .

[0014] There are various ways of measuring the magnetic fields produced by the current carrying conductor but , in some cases , the magnetic field exceeds the limits of the - magnetic sensing element . This can lead to the fact that the sensor is unable to measure currents beyond its operating range .

[0015] Detailed description

[0016] The present disclosure provides an apparatus and method for measuring a current applied to an electrical conductor .

[0017] In some example embodiments , at least one non-conductive region is inserted in the conductor, separating the conductor in a main current path and at least one sense current path . The sense current path carries a proportion of the total current applied to the electrical conductor .

[0018] A magnetic field is created, when the current is applied to the conductor , A magnetic field sensor senses the created magnetic field in the area of the sense current path .

[0019] Current carrying conductor

[0020] The current carrying conductor is an electrically conductive body .

[0021] The current carrying conductor conducts current .

[0022] A so-called electrical conductivity allows the current to flow through the current carrying conductor .

[0023] The current carrying conductor is generally manufactured from at least one metal . Among other metals , the current carrying conductor may be made from copper .

[0024] The current carrying conductor can also comprise an alloy of a variety of metals .

[0025] In some embodiments , the current carrying conductor can be a busbar . The busbar can be made of a rectangular flat metal body . The busbar may be a flat stripe . It may al so be provided as a solid bar or a rod . Busbars can be formed in a number of different shapes . Methode Electronics Malta Ltd. 26154 / 23

[0026] Exemplary, but not exclusively, the busbar can be made of a rectangular flat metal body . The busbar can be a flat stripe . It can also be provided as a solid bar or a rod . Busbars can be formed in a number of different shapes .

[0027] The busbar is made for distributing high current power . The busbar usually has sufficient stiffness . The busbar may be sufficiently stiff or rigid to support its own weight . The busbar may also be sufficiently stiff or rigid to support forces imposed by mechanical vibration as well as accumulated precipitation in outdoor exposures .

[0028] In embodiments , the busbar is composed of copper , brass or aluminium.

[0029] A current flowing through the current carrying conductor generates a magnetic field . The magnetic field runs perpendicular to the current flowing through the current carrying conductor .

[0030] The magnitude of the magnetic field is proportional to the amount of current flowing through the current carrying conductor .

[0031] The radiant of the magnetic field is influenced by the geometry of the current carrying conductor .

[0032] The main current carrying conductor is referred to in more detail below .

[0033] Non-conductive region arranged in the current carrying conductor

[0034] In embodiments , the current carrying conductor has at least a bore , which is an example of a non-conductive region .

[0035] The current carrying conductor is electrically j oined on both sides of the non-conductive region .

[0036] The non-conductive region can be a gap arranged in the conductor .

[0037] The non-conductive region can be filled with any kind of material . The material of the non-conductive region may comprise magnetic or nonmagnetic materials .

[0038] In the following, it is assumed that one non-conductive region is inserted into the busbar .

[0039] The non-conductive region separates the busbar into a main current path and at least one separate sense current path .

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[0041] There is one magnetic field created around the main current path . Another magnetic field is created around the separate sense current path .

[0042] It goes without saying that next to the main current path one or more sense current paths can be arranged .

[0043] The arrangement of one single non-conductive region leads to two separate magnetic fields .

[0044] The non-conductive region can be placed in the centre of the current carrying conductor . It goes without saying that the non-conductive region can also be positioned off-centre in the current carrying conductor .

[0045] At least one non-conductive region is arranged in the current carrying conductor . By way of example, in the following it is assumed that one non-conductive region splits the current carrying conductor into different parts .

[0046] In the non-conductive region, the magnetic field runs perpendicular to the current flowing through the current carrying conductor .

[0047] The non-conductive region arranged in the current carrying conductor separates the total current so that at least one portion of the total current flows through at least one separate sense current path .

[0048] Main current path and separate sense current path

[0049] The non-conductive region separates at least one sense current path from the main current path of the conductor .

[0050] Each sense current path carries a proportion of a total current of the electrical conductor .

[0051] A separate sense current path of the current carrying conductor is a path, spatially separated from the main current carrying conductor .

[0052] Electrically two or more sense current paths can run parallel to the main current path .

[0053] Electrically the at least two sense current paths can run parallel to each other .

[0054] Each current path carries a smaller proportion of the total current carried by a non-separated main current carrying conductor .

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[0057] The sense current path can be referred to as a lower sense current path .

[0058] Several proportional sense current paths can be arranged next to each other .

[0059] The current carried by a sense current path is a ratio of the total current carried by the main current carrying conductor .

[0060] Thus , the sense current path produces a smaller proportion of the total magnetic field produced by the main current carrying conductor .

[0061] The reduced current carried by the sense current path can be set to a level compatible to the magnetic sensing element .

[0062] The main current path may be used for sensing the current . The magnetic field is reduced by separating a sense current path from the main current path through the non-conductive region .

[0063] Magnetic field sensor

[0064] The magnetic field sensor measures the magnetic field generated by the current flowing through the current carrying conductor .

[0065] The magnetic field sensor senses the created magnetic field in the area of the sense current path .

[0066] The magnetic field sensor measuring the magnetic field generated by the current flowing through the current carrying conductor, can be a Hall effect sensor . The current sensor can also be a flux gate sensor or a magneto-resistive current sensor .

[0067] It goes without saying that the magnetic field sensor can also be any other sensor measuring a magnetic field .

[0068] The sensor can be a semiconductor current sensor arranged in a hole of the conductor .

[0069] Detailed Embodiments

[0070] According to an embodiment of the present disclosure, the conductor is a busbar .

[0071] In another embodiment, the conductor comprises at least two regions with uniform current density .

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[0074] In some embodiments, the conductor comprises at least two regions with uniform current density .

[0075] One of the regions can be a non-conductive region consisting of magnetic material .

[0076] According to yet another embodiment of the invention, the non-conductive region is arranged in the centre of the body .

[0077] Embodiments show that the sense current path run parallel to each other . The sense current path can also run parallel to the main current path .

[0078] Advantages

[0079] Standard magnetic field sensors can be applied over any current range .

[0080] The sense current path can be adapted to any application .

[0081] By way of example , an approach according to this disclosure can be applied to highly sensitive magnetic field sensors .

[0082] The sense current path provides a high resolution current measurement .

[0083] The current disclosure allows an application for current values that are not subj ect to any limit . The sensitivity of magnetometers known in the art often limits the range of application to low current measurements . Typically, low current measurements performed by magnetometers known in the art often range about -200A .

[0084] Advantageously, the approaches of the present disclosure improve the immunity of a current magnetic field sensor relative to background magnetic fields .

[0085] Drawings

[0086] Further examples and advantageous embodiments are described in more detail below by means of the following figures . The figures show :

[0087] Fig . 1 an axial view of a magnetic flux surrounding a single current carrying conductor , with theoretical measurement guide points 24 in all ,

[0088] Fig . 2 a magnetic field strength along a straight line , at a distance above the conductor surface . On a line interconnection three Methode Electronics Malta Ltd, 26154 / 23 of the aligned measurement guide points represent the measurement line A to B

[0089] Fig. 3 a magnetic field strength normal to the measurement line,

[0090] Fig . 4 a magnetic field strength tangential to the measurement line and magnetic field,

[0091] Fig . 5 an axial view of the magnetic flux surrounding a current carrying conductor with a non-conductive region, in the region C2,

[0092] Fig . 6 a normal flux along the width of the conductor in Fig. 5,

[0093] Fig . 7 the tangential field strength measure for the conductor of Fig. 5,

[0094] Fig . 8 a field plot created to illustrate a tangential field strength of a region C3,

[0095] Fig . 9 a field plot created to illustrate a tangential field strength of a another region Cl,

[0096] Fig. 10 a current carrying conductor with a non-conductive region created by a gap, and

[0097] Fig. 11 a conductor (busbar) showing a non-conductive region.

[0098] The Y-axis of the coordinate system of the Fig. 2, 3, 4, 6, 7, 8 and 9 shows mT -values (millitesla) .

[0099] The X-axis of the coordinate system of the Fig. 2, 3, 4, 6, 7, 8 and 9 shows length-values in mm (Millimetre) . Along the measurement line between points A and B.

[0100] Fig. 1 shows an axial view of a magnetic flux.

[0101] Fig. 1 represents a magnetic flux surrounding a single current carrying conductor .

[0102] The single current carrying conductor is composed of connected regions Cl, C2, C3.

[0103] In the Fig. 1 the connected regions Cl, C2, C3 have a uniform current density in all regions.

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[0105] By way of example , Fig . 1 represents a single solid conductor with a cross section . The cross section can be 4mm by 50mm . It goes without saying that other values can be applied as well .

[0106] In Fig . 2 the magnetic field strength is shown along a straight line . The straight line stretches from a given point A at 0mm to a given point B at 45mm . It goes without saying that other values can be applied as well .

[0107] The measurement line of Fig . 2 is shown in a free space . The space ranges about 3mm from the surface of the conductor . It goes without saying that other values can be applied as well .

[0108] By way of example, in the Fig . 2 the field strength has the value of 21mT . Across the width of the conductor peaks are shown in the vicinity of the conductor ends .

[0109] Fig . 3 represents the magnetic field strength normal to the measurement line . The magnetic field strength is measured from 3mm above the conductor .

[0110] The magnetic field strength of Fig . 3 stretches between a point A and a point B . The magnetic field strength stretching between the points A and B can be expected with the flux circulating the conductor in an anticlockwise direction .

[0111] The flux vector around point A is at 0mm . The vector stretches to the right and is negative in magnitude .

[0112] In Fig . 3 the magnetic flux around point B is at 45mm . It runs in the positive direction . As expected the flux direction rotates through 180 degrees across the width of the conductor .

[0113] The magnetic field strength curve of Fig . 4 is tangential to the measurement line .

[0114] The magnetic field strength curve stretches 3mm above the conductor .

[0115] The magnetic field strength curve stretches between a point A and a point B . The magnetic field strength stretching between the points A and B can be expected with a flux circulating the conductor in an anti-clockwise direction .

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[0118] In Fig . 4 the tangential flux vector around point A is at 0 mm, meaning the tangential flux vector is low in magnitude .

[0119] The magnetic flux around point B is at 45mm, meaning it also has a low value .

[0120] As expected, in Fig . 4 the tangential flux magnitude rises to a maximum.

[0121] The maximum is set around a mid-point across the width of the conductor .

[0122] Fig . 5 shows an axial view of Magnetic flux surrounding a single current carrying conductor .

[0123] The single current carrying conductor of Fig . 5 is composed of connected regions Cl , C2 , C3 with uniform current density in regions Cl and C3 .

[0124] In Fig . 5 region C2 is a so-called non-conductive region .

[0125] By way of example, Fig . 5 shows a conductor with a cross section of 4mm by 50mm . The conductor has regions Cl 4 x 30 , C2 4 x 5 and C3 is 4 x 10 . It goes without saying that other values can also be applied .

[0126] A raw conductor as shown in Fig . 5 can be used to manufacture the conductor (busbar ) , which has a non-conductive region . The raw conductor has a continuous shape across its width . The raw conductor has the continuous shape in another plane above and below the section shown in Fig . 5 .

[0127] To create the conductor (busbar) , provided with a non-conductive region, > a non-conductive region of undefined length or shape is arranged in the raw conductor (busbar ) . The non-conductive region arranged in the raw conductor (busbar ) can be formed by a slot or a gap or a bore arranged in the raw conductor . It goes without saying that the non-conductive region ( e . g . slot or a gap or a bore ) can also have a different geometric shape .

[0128] In the disclosure of Fig . 5 the non-conductive region ( e . g . slot or a gap or a bore ) is filled with any kind of material . The material of the non-conductive region may comprise magnetic or non-magnetic materials .

[0129] In the example of Fig . 5 the magnetic flux circulating the two conducting regions Cl and C3 is created in proportion to the currents flowing in Cl and C3 .

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[0132] Fig . 5 shows the interactions between the flux of the regions Cl , C3 and the non-conductive region C2 .

[0133] Fig . 6 shows the normal flux along the width of the conductor as shown in Fig . 5 . The normal flux is measured along a straight sense current path between point A and Point B .

[0134] The region ranging between 30mm and 35mm coincides with the non-conductive region .

[0135] For the conductor shown in Fig . 5 the tangential field strength measured along the line from point A to point B shows two distinct regions in Fig . 7 .

[0136] In Fig . 7 the mid of the 30mm section Cl shows a field strength of around 20mT, wherein in Fig . 7 the field strength around the 10mm Section C3 has a peak at 15mT .

[0137] In the example of Fig . 6 the flux produced around the region Cl interacts with the flux of the region C3 . Thus , due to the current density a filed strength is produced higher than that of C3 alone .

[0138] Following the example of Fig . 8 a current cannot pass through region C3 alone . The field plot of Fig . 8 illustrates the tangential field strength of region C3 above its mid-point at 40mm .

[0139] The field strength ranges about 12 . 5mT . In the example of Fig . 8 , the conductor contributes 12 . 5mT of the 15mT as observed in Figure 7 at the 40mm location .

[0140] Following the example of Fig . 9 a current cannot pass through region Cl alone . The field plot of Fig . 9 illustrates the tangential field strength of regions Cl and C3 . In Fig . 9 the field strength is 20mT at 15mm and around 2 . 5mT at 40mm .

[0141] The corresponding part of the conductor contributes 2 . 5mT of the 15mT as observed in Fig . 7 at the 40mm location .

[0142] The sum of the two conducting elements reaches a total of 15mT as observed at 40mm in Figure 7 .

[0143] Fig . 10 shows a current carrying conductor with an aperture to create proportional current flow and magnetic fields .

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[0146] In the example of Fig. 10, the conductor has a rectangular shape with a linear aperture. It goes without saying that the conductor can also have other geometrical shapes. The conductor is joined effectively either side of the aperture.

[0147] In Fig. 10 IT represents the total current in the conductor.

[0148] Both II and 12 represent proportional currents, whereas FT is the total magnetic field as a result of the total current in the conductor IT.

[0149] In Fig. 10 Fl and F2 stand for magnetic fields as a result of the proportional currents II and 12, respectively.

[0150] In the Fig. 10 a non-conductive region slot extends along the length of the current carrying conductor.

[0151] The slot represents the non-conductive region arranged in the measurement region of the current carrying conductor.

[0152] In the Fig. 10 the slot (bore) penetrates the thickness of the material of the current carrying conductor.

[0153] The non-conductive region of Fig. 10 having the form of a slot can consist of any kind of magnetic or non-magnetic materials.

[0154] The non-conductive region (slot) separates the current carrying conductor of Fig. 10 into a main current carrying conductor and one separate sense current paths .

[0155] The arrangement of the non-conductive region (slot) of Fig. 10 leads to two separate magnetic fields Fl and F2.

[0156] There is one magnetic field Fl created around the main current carrying conductor. Another magnetic field F2 is created around the separate sense current path.

[0157] Thus, in the arrangement of Fig. 10 one single non-conductive region (slot) leads to two separate but proportional magnetic fields Fl and F2.

[0158] The magnetic field F2 is the result of the current 12 flowing through the separate sense current path of the current carrying conductor.

[0159] In the Fig. 10 the magnetic field Fl is the result of the current II flowing through the main current carrying conductor.

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[0162] The magnetic fields Fl and F2 sum up to the total magnetic field FT . The total magnetic field FT is the result of the total current IT flowing through the current carrying conductor .

[0163] Magnetic fields Fl and F2 run perpendicular through the single non- conductive region ( slot ) of the current carrying conductor, respectively .

[0164] In the areas of the current carrying conductor that are not separated by the non-conductive region ( slot ) , the FT magnetic field runs at right angles around the current carrying conductor .

[0165] Fig . 11 shows a conductor (busbar) 12 having a non-conductive region 11 .

[0166] A non-conductive region 11 is inserted in the conductor (busbar ) 12 . The non-conductive region 11 separates the conductor 12 in a main current path 13 and at least one sense current path 14 . The sense current path 14 carries a proportion of the total current 15 applied to the electrical conductor 12 .

[0167] A magnetic field is created, when the current 15 is applied to the conductor 12 . The magnetic field sensor 10 senses the created magnetic field 18 in the area of the sense current path 14 .

[0168] The current carrying conductor 12 is an electrically conductive body carrying current 15 .

[0169] The current 15 flowing through the current carrying conductor 12 generates a magnetic field . The magnetic field runs perpendicular to the current 15 flowing through the current carrying conductor 12 .

[0170] The current carrying conductor 12 has one bore 16 . The bore 16 is the non-conductive region 11 .

[0171] The non-conductive region 11 is shown as a bore 16 arranged in the conductor (busbar ) 12 .

[0172] The non-conductive region 11 is filled with any kind of material (not shown) .

[0173] The non-conductive region 11 of Fig . 11 separates the conductor (busbar ) 12 into a main current path 13 and a separate sense current path 14 . Methode Electronics Malta Ltd, 26154 / 23

[0174] The arrangement of the non-conductive region 11 leads to two separate magnetic fields 17 and 18 .

[0175] One magnetic field 17 is created around the main current path 13 . Another magnetic field 18 is created around the sense current path 14 .

[0176] The arrangement of one single non-conductive region 11 in the conductor (busbar ) 12 leads to two separate magnetic fields 17 , 18 .

[0177] In the non-conductive region 11 of the conductor (busbar ) 12 , the separate magnetic fields 17 , 18 run perpendicular to the current 15 flowing through the current carrying conductor (busbar) 12 .

[0178] The magnetic fields 17 , 18 concentrate towards the centre of the bore 16 of the current carrying conductor (busbar ) 12 .

[0179] The non-conductive region 11 arranged in the current carrying conductor (busbar) 12 separates the total current 15 so that at least one portion of the total current 15 flows through the separate sense current path 14 .

[0180] In the example shown in Fig . 11 the sensor 10 (e . g . magnetic field sensor ) is arranged in a stable position relative to the conductor 12 so that the sensor 10 measures the separate magnetic field 18 of the sense current path 14 .

[0181] In other words , the magnetic field sensor 10 senses the created magnetic field 18 in the area of the sense current path 14 .

[0182] The non-conductive region 11 consisting of magnetic material ( not shown) .

[0183] The sense current paths 14 of the current carrying conductor (busbar) 12 runs parallel to the main current path 13 .

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[0186] List of references

[0187] IT total current

[0188] 11 proportional current

[0189] 12 proportional current

[0190] FT total magnetic field

[0191] Fl magnetic field

[0192] F2 magnetic field

[0193] 10 sensor

[0194] 11 non-conductive region

[0195] 12 conductor / busbar

[0196] 13 main current path

[0197] 14 sense current path

[0198] 15 current

[0199] 16 bore

[0200] 17 separate magnetic field

[0201] 18 separate magnetic field

[0202] 14

[0203] Dll / 26

Claims

Methode Electronics Malta Ltd. 26154 / 23Claims1 . Method for measuring a current applied to an electrical conductor , wherein at least one non-conductive region is inserted in the conductor, separating the conductor in a main current path and at least one sense current path, wherein the sense current path carries a proportion of the total current applied to the electrical conductor, and wherein a magnetic field sensor senses a magnetic field in the area of the sense current path .2 . Method for measuring a current according to claim 1 characterized in that the conductor is a busbar .3 . Method for measuring a current according to claim 1 characterized in that the current is applied to the conductor comprising at least two regions with uniform current density .4 . Method for measuring a current according to claim 1 characterized in that the sense current paths created by inserting the non- conductive region in the conductor, run parallel to each other .5 . Method for measuring a current according to claim 1 , characterized in that the sense current path is created by inserting the non- conductive region in the conductor .15Dll / 26

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