Differential current sensor for large currents

Abstract

A magnetic core for a current sensor is described in the following. According to one exemplary embodiment, the magnetic core comprises a first core portion and a second core portion, each core portion being composed of a stack composed of a plurality of metal sheet layers. The second core portion has a first end piece which is configured such that the metal sheet layers have some longer metal sheet layers and the longer metal sheet layers protrude from the remaining shorter metal sheet layers. The first core portion has a second end piece which is configured in an opposite manner to the first end piece of the second core portion. The first core portion and the second core portion are joined together at a connection location such that the longer metal sheet layers of the first end piece and the second end piece (310) overlap at the connection location, wherein according to the exemplary embodiment the first end piece and the second end piece are designed in such a way that the overlap occurs at a number of interfaces which is at least two (in particular three) less than the number of metal sheet layers.

Description

Technical Field

[0001] This invention relates to the field of current sensors, and in particular to a differential current sensor for relatively large currents. Background Technology

[0002] In non-contact current measurement, current sensors are primarily used. These sensors analyze the magnetic field generated by the current being measured (primary current) flowing through the so-called primary conductor, thereby determining the actual current flowing in the primary conductor. Non-contact current sensors, meaning those that do not have any current contact with the primary conductor, are mainly used for high currents.

[0003] Current sensors can be designed in different ways, particularly in terms of the magnetic field sensors and magnetic modules used within them. Magnetic field sensors (also known as magnetic field probes) are primarily inductive or Hall effect-based types. Soft magnetic elements (such as magnetic cores made of soft magnetic materials) are used to focus or guide the magnetic field, and these soft magnetic elements are an important component of the magnetic module.

[0004] In the case of a so-called compensated current sensor, the magnetic field generated by a compensated current of known strength compensates for the magnetic field generated by the primary current to zero. For example, a magnetic core with a closed structure, such as a circular or rectangular ring structure (toroidal core), is used as a soft magnetic element, typically with an air gap to accommodate the magnetic field probe. The residual magnetic field remaining after incomplete compensation is measured using the magnetic field probe, and the compensated current is readjusted accordingly. In this case, the compensated current is a measure of the primary current.

[0005] These types of current sensors can also be used to measure differential current. In this case, two current-carrying primary conductors are typically guided through a magnetic core in such a way that the magnetic fields induced by the respective primary currents are destructively superimposed within the core. Therefore, the magnetic flux generated in the core is proportional to the difference between the primary currents in the two conductors, and thus, the current sensor measures the differential current. The differential current can be several orders of magnitude smaller than the primary currents flowing through the two primary conductors. Therefore, in some applications, a differential current of a few milliamperes (e.g., 10 mA) should be measured, while the primary current may be approximately 500 amperes. In this case, the ratio of the differential current to the primary current is 1:50000.

[0006] Another problem with differential current sensors is the asymmetrical arrangement of the two primary conductors (to measure the current difference) relative to the magnetic core, which can lead to local saturation in the magnetic core. Summary of the Invention

[0007] The purpose of this invention is to provide a differential current sensor that can measure very small differential currents with sufficient accuracy, even when the conductor current is very large.

[0008] The solution of the present invention to achieve the above-mentioned objective lies in the magnetic core described in this application.

[0009] The magnetic core for a current sensor is described below. According to an exemplary embodiment, the magnetic core includes a first core and a second core, each core being composed of a stack of multiple metal sheets. The second core has a first end member configured such that some of the longer metal sheets protrude from the remaining shorter metal sheets. The first core has a second end member configured in the opposite manner to the first end member of the second core. The first and second cores are joined together at a connection point such that the longer metal sheets of the first and second end members (310) overlap at the connection point, wherein, according to this exemplary embodiment, the first and second end members are structured such that overlap occurs at several interfaces, the number of which is at least two (particularly three) fewer than the number of metal sheets. This magnetic core is particularly suitable for differential and summative current sensors having two or more primary conductors.

[0010] According to another exemplary embodiment, the metal sheets in the first end member and the second end member are respectively formed into irregular comb-like structures. According to another exemplary embodiment, the proportion of the longer metal sheet of the first end member to the total cross-sectional area of ​​all metal sheets is less than 40%. Attached Figure Description

[0011] Exemplary embodiments will now be described in detail with reference to the accompanying drawings. These drawings are not necessarily to scale and these exemplary embodiments are not limited to the aspects shown. Rather, the focus is on illustrating the principles upon which these exemplary embodiments are based. Wherein: Figure 1 An example of a compensated current sensor with a fluxgate probe is illustrated with a block diagram. Figure 2 A first example of a magnetic core formed by joining two core sections is shown; Figure 3 A second example of a magnetic core formed by joining two core sections is shown; Figure 4 The design of the end pieces of a standard magnetic core is shown to enable the cores to be joined together; Figure 5 A graph illustrating the sensitivity of different differential current sensor designs; Figure 6 and Figure 7 Two exemplary configurations of the end piece of the core of an improved magnetic core, which is more suitable for differential current sensors, are shown. Figure 8 An example of another end piece with the core constructed in the opposite manner is shown; Figure 9 The cross-sectional view shows a differential current sensor with a shield assembled together. Detailed Implementation

[0012] The embodiments described herein relate to magnetic cores for use in compensation current sensors. Before discussing the various aspects of the magnetic core in detail, a brief description of the already known basic structure of compensation current sensors is provided. An example is... Figure 1 As shown in the image.

[0013] according to Figure 1 The current sensor includes a magnetic core 3 made of soft magnetic material, which is magnetically coupled to two primary windings 5a and 5b and a secondary winding / compensation winding 4. The primary winding 5a carries a primary current i. P1 The primary winding 5b carries the primary current i P2 i P1 -i P2 The difference is the differential current to be measured. Compensation winding 4 carries the compensation current i. S (Secondary current). From the primary current i P1 and i P2 The resulting magnetic flux components are destructively superimposed in the magnetic core 3; therefore, only the differential current i P1 -i P2 and secondary current i S It contributes to the entire magnetic field, which is achieved by adjusting the secondary current i S The magnetic flux generated in core 3 is adjusted to zero. This adjustment is made using a current regulator for the secondary current, which will be described later.

[0014] The differential magnetic flux is measured using a magnetic field probe 20, which includes a ferromagnetic metal strip referred to as "sensor strip 21" and a sensor coil 22 surrounding the sensor strip 21. The sensor coil 22 is connected to an analysis circuit 41, which provides a measured value B representing the magnetic flux. Different applicable analysis circuits are known and will not be described further here.

[0015] Analysis circuit 41 typically includes an oscillator that generates an excitation current i MThe excitation current is fed into sensor coil 22 and periodically magnetized by changing polarity until sensor band 21 is saturated. Based on the symmetrical, ideally rectangular hysteresis characteristic curve of sensor band 21, the asymmetry that may exist when alternating magnetization of sensor coil 22 indicates that the magnetic flux in magnetic core 3 is not zero. This asymmetry can be analyzed. The analysis circuit is coupled to current regulator 42, which regulates the secondary current i. S This causes the aforementioned asymmetry to disappear or the measured value B to (ideally) become zero. This type of magnetic field probe is also known as a fluxgate probe. Furthermore, an example is described in publication DE 10045194 A1 (corresponding to US 2004 / 0204875 A1).

[0016] In this state (measured value B is zero), the compensation current i S With differential current i P1 -i P2 Proportional, where the proportionality coefficient is related to the ratio of the number of turns in the primary windings 5a and 5b to the number of turns in the compensating winding 4. This can be measured very precisely, for example, by measuring the resistance R. S To measure the adjusted compensation current i S And based on the above ratio, the resulting measured values ​​(e.g., output voltage V) O =R S ×i S () represents the differential current i P1 -i P2 In practice, the number of turns in the primary windings 5a and 5b is usually equal to 1 (i.e., the primary conductor passes through the toroidal core).

[0017] The above concept also applies to the measurement of the sum of currents in two or more primary conductors, such as the measurement of the sum of currents in the three-phase conductors and the neutral conductor of a three-phase connection. Theoretically, this sum should be zero; therefore, a sum of currents greater than zero is also called a fault current. The differential current i mentioned above... P1 -i P2 It can also be the current difference between the phase conductor and the associated neutral conductor, which can also be called the fault current. In this regard, it should be noted that there are also compensated current sensors that operate using two magnetic field probes. Two or more compensation coils can also be used.

[0018] Another type of current sensor is the so-called open-loop current sensor, in which the compensation winding 4 is not required, and therefore the current regulator 42 is also unnecessary. In this case, the differential current i is measured directly in the air gap of the magnetic core using the magnetic field probe 20 (rather than indirectly through the compensation current). P1 -i P2(Or it could be a fault current) the field generated in core 3. The core described herein is suitable for both types of current sensors, but has certain advantages when using a differential current sensor.

[0019] Compensated current sensors can measure both DC and AC currents, with transformer coupling between the primary and secondary conductors being relevant to AC current measurement.

[0020] Figure 2 The illustration (a) shows two parts of a magnetic core 3 in an unassembled state (e.g., in a magnetic module for a differential current sensor, particularly a compensating current sensor). In this case, the two parts of the magnetic core 3 consist of two L-shaped core portions 31 and 32 (legs) with the same design, wherein each core portion may, for example, have a rectangular core cross-section (not shown in the figure). Figure 2 (As shown in the diagram). Cores 31 and 32 are essentially two rod-shaped magnetic cores, each bent at 90°. In this case, the bending points 33 and 34 can be precisely right-angled with the sharp edges or—as shown in the diagram. Figure 1 As shown—it can be arbitrarily rounded or beveled. Grooves 6 and 7 are provided on the end faces of cores 31 and 32 along the length direction L (dotted line) of the corresponding cores. When the magnetic core 3 is assembled, these grooves provide space for accommodating the magnetic field probe. In this case, grooves 6 and 7 can be designed such that they are surrounded by the core material on all sides, except for a small through-hole for the magnetic field sensor's inlet wire, or open to one or both sides.

[0021] Figure 2 The diagram (b) shows the magnetic core 3 in its assembled state. During the assembly of the magnetic core 3, the two cores 31 and 32 are arranged adjacent to each other, such that the grooves 6 and 7 of the cores 31 and 32 together form a receiving space for the magnetic field probes 20a and 20b.

[0022] In the assembled state, there is space for supplying two or more primary windings or primary conductors (see...). Figure 1 The internal opening 8 through which the first windings 5a and 5b pass. In other words, the assembled cores 31 and 32 form a closed magnetic core 3. In this case, the junction between cores 31 and 32 forms an air gap, but these air gaps have a small gap width, for example, less than 0.1 mm. An air gap generally refers to the space between two closely opposed surfaces. In this case, the gap width is the distance between the two surfaces along a perpendicular line (normal distance). The effective gap width is the distance from a non-planar structure spaced a certain distance to a planar structure.

[0023] Figure 3 The illustrations (a) and (b) in the figure show Figure 2A variation of the example shown, wherein a groove 6 is arranged only on one end face of each of the cores 31 and 32, which, in the assembled state, provides space for magnetic field probes 20a and 20b, respectively.

[0024] According to the embodiments described herein, cores 31 and 32 are made of materials having a relatively small coercive field strength H. C (e.g. H) C Materials with a hysteresis error of <0.02 A / cm are used to minimize this error. For this purpose, nickel-iron alloys with a nickel content of 72-83%, such as VCOPERM, can be used. ® 100 (H) C (≈ 0.01 A / cm), but its disadvantage is its low saturation polarization intensity. In traditional current sensors, nickel-iron alloys with higher saturation polarization intensity and greater coercive field strength are usually used, especially nickel-iron alloys with a nickel content of 45-50%, such as PERMENORM. ® 5000 V5. When using a differential current sensor, in addition to the asymmetry related to the geometry of the field distribution (e.g., due to the asymmetrical arrangement of the busbars), the field of all primary currents flowing through the sensor is inherently pre-compensated (vector summation). Therefore, the core material only needs to homogenize a portion of the superimposed magnetic flux so that the actual difference (fault current) can be measured. Thus, a lower saturation polarization intensity plays a secondary role in differential current sensors.

[0025] As described above, in the embodiments described herein, the fluxgate probe is used as a magnetic field sensor (see [link]). Figure 2 and Figure 3 Magnetic field probes (20a-b). These probes are typically used in current sensors to measure conductor current (rather than differential current). However, known fluxgate probe designs are generally not sensitive enough for differential current sensors. As mentioned earlier, magnetic field probes (in addition to the necessary sensor electronics) typically include those using magnetic materials (e.g., VITROVAC). ® A metal strip (commonly referred to as a sensor strip) is made of which a coil is wound. The material constituting the sensor strip does have a region of nonlinear magnetization, but exhibits very symmetrical hysteresis. The sensor strip is made of a relatively thin film, for example, with a thickness of 20 µm. The sensor strip is typically mounted on a coil holder, and the coil is wound around the coil holder, and thus also around the sensor strip. To improve the sensitivity of the probe, the effective cross-sectional area of ​​the sensor strip can be set larger than that of a conventional current sensor probe. This increase in cross-sectional area is achieved by increasing the thickness of the sensor strip (e.g., from 20 µm to 40 µm or greater) or by using a stack of two or more sensor strips.

[0026] The inventors discovered that simply using a sensor with a larger cross-sectional area to improve the sensitivity of the magnetic field probes 20a and 20b is insufficient; that is, it does not achieve the desired effect of higher sensitivity in the differential current sensor. Furthermore, according to the embodiments described herein, for Figure 2 or Figure 3 The magnetic core 3 shown in the simplified diagram has been improved, which will be discussed below.

[0027] Figure 4 This illustration shows the cores 31 and 32 being connected together to form a shape as shown. Figure 3 The magnetic core 3 is shown. According to... Figure 4 The cores 31 and 32 consist of multiple stacked metal sheets ( stacked sheet metal layers It is assembled from various parts. Figure 4 In the example shown in (a), the core consists of 16 stacked layers of metal sheets, wherein at the first end piece 320 of the core 32, each second layer is longer than the next by a specific distance, thereby forming a comb-like structure at the first end piece 320, which can be inserted into a corresponding comb-like structure on the end piece of the core 31. Identical comb-like structures with uniformly alternating "tooth" are provided on the opposite ends of these cores. In the joined state, the individual layers of the stacked metal sheets overlap at the connection point X (see...). Figure 3 The illustration (b) and Figure 4 As shown in Figure (b), cores 31 and 32 are composed of these layers. This type of connection is somewhat similar to, for example, finger joints used in woodworking (…). box joint In other words, the even-numbered metal sheets of core 32 overlap with the odd-numbered metal sheets of core 31 at connection point X. When the number of metal sheets is even, half of these metal sheets overlap with the corresponding metal sheet of another core. When the number of metal sheets is odd, there is one less than half. In the assembled state, the shorter metal sheet of the first end piece 320 rests its end face against the side of the adjacent metal sheet of core 31 (see...). Figure 4 (See illustration (b)).

[0028] The following will be by Yi Ru Figure 4 The toroidal magnetic core formed by the two cores 31 and 32 connected as shown is called a standard magnetic core. Furthermore, the grooves for the probe magnetic fields 20a and 20b (see...) Figure 2 and Figure 3 Adjacent to connection point X (see Figure 3 (See diagram (b)) or even extend into the connection point (see diagram (b)). Figure 2 (See illustration (b)).

[0029] Figure 5This is a graph used to describe the measured values ​​representing the sensitivity of a differential current sensor. Figure 5 The graph contains three characteristic curves, which represent the duty cycle of the modulated output signal of the current sensor as a function of the differential current to be measured, where a 50% duty cycle at the output of the current sensor indicates a differential current of 0 mA. The first characteristic curve (solid line) shows the sensitivity of the current sensor with a standard magnetic core and a standard probe (a fluxgate probe with a sensor band). The second characteristic curve (dotted line) shows the sensitivity of the current sensor with a standard magnetic core and a modified probe comprising two overlapping sensor bands (doubling the cross-sectional area). It can be seen that the sensitivity of the current sensor is only slightly affected by the modification of the described magnetic field probe (the enlargement of the effective core cross-section of the sensor band). At currents below 200 mA, the difference between the first and second characteristic curves is practically invisible in the graph.

[0030] The third characteristic curve (dashed line) shows the sensitivity of the current sensor with a probe featuring an improved magnetic core and an increased cross-section of the modified iron core (as described above). The core improvement primarily involves the connection type of the two cores 31 and 32. Different embodiments in... Figure 6 and Figure 7 As shown in the diagram. What these two variations have in common is that the comb-like structure located at the first end piece 320 of the core 32 is designed such that, when the cores are joined together, it conforms to... Figure 4 Compared to a standard magnetic core (where each second metal sheet layer overlaps with a corresponding metal sheet layer in another core), there are fewer overlapping metal sheet layers. Most of these metal sheet layers (in...) Figure 6 Of the sixteen, ten (62.5%) were in the middle. Figure 7 Of the sixteen (75%), twelve—without overlap—are attached to the side of the corresponding metal sheet of the other core with their narrower end faces. A small air gap (in the range of 100 µm) can be formed between the adjacent metal sheets at their end faces / side faces, thereby increasing the leakage flux.

[0031] In other words, in the first end piece 320 of the core 32, not every second metal sheet protrudes beyond the shorter metal sheet by a distance a; rather, less than approximately 40% of the metal sheets are longer than the remaining shorter metal sheets. Figure 6 In the example shown, six of the sixteen metal sheets (representing 37.5% of the cross-sectional area) protrude beyond the remaining shorter metal sheets. Figure 7In the example shown, four out of sixteen metal layers (i.e., 25% of the cross-sectional area) are represented. In a standard magnetic core with an even number of metal layers, 50% of the metal layers are always longer than the shorter ones. In a standard magnetic core with an odd number of metal layers, one less layer is represented. According to the exemplary embodiments described herein, with a conventional metal layer thickness of, for example, 0.2 mm to 0.5 mm, the magnetic core may consist of, for example, eight or more metal layers.

[0032] The above explanation also shows that when using a standard magnetic core with N metal layers (a regular comb-like structure with alternating protruding metal layers), there are always N-1 interfaces ( interface areas The metal sheets of cores 31 and 32 overlap at these interfaces. With a modified core, there are N-2 or fewer interfaces. Theoretically, the limiting case would be N=3 metal sheets overlapping at exactly one (N-2) interface (in the first end piece 320, the first or last metal sheet will protrude beyond the other two metal sheets by a distance a). However, overlap at a single interface is not as mechanically stable as multiple overlaps. With a core having N=4 metal sheets, if the outer two metal sheets or the inner two metal sheets in the first end piece 320 protrude beyond the other metal sheets by a distance a, overlap can occur at two interfaces (similar to...). Figure 7 (Example shown). In the case of a regular comb-like structure (standard magnetic core) with alternating protruding metal sheets, the first and third (or second and fourth) metal sheets in the first end piece 320 will protrude.

[0033] As described above, it may be advantageous if the longer metal sheets in the first end piece 320 occupy at most 40% of the total cross-sectional area of ​​the magnetic core. This maximum of 40% can be achieved precisely when using a magnetic core with N=5 metal sheets and overlapping at N-2=3 interfaces (assuming the metal sheets have the same thickness). In this case, to achieve an irregular comb-like structure, the first and fourth (or second and fifth) metal sheets are longer than the remaining metal sheets. A regular comb-like structure always exists when each second metal sheet does not alternately protrude beyond its adjacent metal sheet (see...). Figure 4 (This shows a regular structure), which also indicates that the longer metal sheets in the first end piece 320 are not arranged equidistantly (i.e., not in a regular grid). In one example, this is for overlap at six (N-2) or fewer (e.g., N-4) interfaces, where N is greater than or equal to 5 (preferably greater than or equal to 8).

[0034] Figure 8 This is a photograph of the second end piece 310 of the core 31, which is related to... Figure 7 The first end piece 320 of the core 32 shown corresponds to this. In the joined state, the following is obtained: Figure 2 The magnetic core shown. In the example shown, with sixteen metal layers, only eight interfaces will overlap. With a standard magnetic core having the same number of metal layers, there will be fifteen interfaces.

[0035] Figure 9 This is a cross-sectional view of the assembled differential current sensor, which has a magnetic core 3 composed of cores 31 and 32 as described above. The junction is located at... Figure 9 The shielding component (parts 51-54) covers (its in) Figure 9 (Located at the right rear), cores 31 and 32 are assembled together at this joint point. A circuit board 55 is located inside the housing and above the magnetic core 3, on which sensor electronics (signal conditioning device, magnetic field probe activation device, analog-to-digital converter, microcontroller, etc.) are mounted. Different applicable electronic circuits are known and will not be described further here.

[0036] exist Figure 9 In the middle, the magnetic core 3 and the compensation coil are surrounded by a shield. The compensation coil is... Figure 9 The core 3 is not visible because it is covered by a shield. This shield improves the differential current sensor's immunity to external magnetic fields, and also improves its immunity to asymmetry, particularly to asymmetric arrangements of the primary conductors. When using a differential current sensor, the latter situation inevitably occurs because two or more primary conductors must pass through the core 3 simultaneously, whereas with a "normal" current sensor, a single primary conductor can be arranged symmetrically with respect to the core 3.

[0037] exist Figure 9 In the illustrated embodiment, the shielding component includes an inner shielding ring 51 arranged along the inner circumference of the magnetic core 3, an outer shielding ring 52 arranged along the outer circumference of the magnetic core 3, an upper shielding plate 54 (top cover shielding component), and a lower shielding plate 53 (bottom shielding component). This omnidirectional shielding of the magnetic core and the compensation coil reduces the sensitivity of the differential current sensor to external (parasitic) magnetic fields. To ensure that the sensor's transmission behavior within the AC range is unaffected by the shielding component, a circumferential air gap (gap width x, see [reference]) is provided between the inner shielding ring 51 and the bottom shielding component 53. Figure 9 Therefore, the air gap extends along the inner circumference of the magnetic core 3. Alternatively, the air gap can be arranged at another location along the inner circumference of the magnetic core 3, for example, between the inner shielding ring 51 and the top cover shielding member 54, or the inner shielding ring can be divided into two parts with a circumferential air gap in between.

[0038] The shielding element can be made of, for example, Mumetall® or VAOPERM ® Made of 100% nickel-iron alloy. Combined with the aforementioned improved magnetic core, this shield enables relatively accurate differential current measurement. The shield can, for example, be positioned inside a plastic housing. This plastic housing, not shown in the figures, actually surrounds the shield on all sides (and consequently the magnetic core, compensation coil, electronic circuit board, etc.). Plastic housings are common in this type of current sensor and will not be described further here.

Claims

1. A magnetic core for a current sensor, the magnetic core comprising: The first core (31) and the second core (32), each of the cores comprising a stack of multiple metal sheets; The second core (32) has a first end piece (320) configured such that some of the metal sheets are longer metal sheets that protrude from the remaining shorter metal sheets. The first core (31) has a second end piece (310), which is constructed in the opposite manner to the first end piece (320) of the second core (32). The first core (31) and the second core (32) are joined together at the connection point, such that the longer metal sheet layers of the first end piece (320) and the second end piece (310) overlap at the connection point; and The first end piece (320) and the second end piece (310) are designed such that the overlap occurs at several interfaces, the number of which is at least two fewer than the number of metal sheets.

2. The magnetic core according to claim 1, The total cross-sectional area of ​​the longer metal sheet located at the first end piece (320) of the second core (32) is less than 40% of the cross-section of the second core (32).

3. The magnetic core according to claim 1 or 2, The stack consisting of multiple metal sheets consists of at least five metal sheets.

4. The magnetic core according to any one of claims 1 or 2, The metal sheet is made of a soft magnetic alloy with a coercive field strength of less than 0.02 A / cm.

5. The magnetic core according to any one of claims 1 or 2, In the second core (32), a groove for a magnetic field probe is provided adjacent to the connection position, the groove extending into the connection position where the overlap occurs.

6. The magnetic core according to any one of claims 1 or 2, The first core (31) and the second core (32) are constructed in the same manner.

7. The magnetic core according to any one of claims 1 or 2, The first core (31) and the second core (32) are connected at two connection points, which are designed in the same way.

8. The magnetic core according to any one of claims 1 or 2, The stack consisting of multiple metal sheets consists of at least five metal sheets; The metal sheet is made of a soft magnetic alloy, and the coercive field strength of the soft magnetic alloy is less than 0.02 A / cm. In the second core (32), a groove for a magnetic field probe is provided adjacent to the connection position, the groove extending into the connection position where the overlap occurs.

9. The magnetic core according to any one of claims 1 or 2, The stack consisting of multiple metal sheets consists of at least five metal sheets; The metal sheet is made of a soft magnetic alloy, and the coercive field strength of the soft magnetic alloy is less than 0.02 A / cm. In the second core (32), a groove for a magnetic field probe is provided adjacent to the connection position, the groove extending into the connection position where the overlap occurs; The first core (31) and the second core (32) are constructed in the same manner; The first core (31) and the second core (32) are connected at two connection points, which are designed in the same way.

10. A current sensor, comprising: According to any one of claims 1 to 9, the first core portion (31) and the second core portion (32) are joined together at two connection locations and the core has two grooves arranged adjacent to the connection locations. Two magnetic field probes are arranged in grooves in the magnetic core; as well as Two compensation windings (4) are arranged on two opposite regions of the magnetic core.

11. The current sensor according to claim 10, further comprising: A shielding element that surrounds the magnetic core on each side and also surrounds the compensating winding (4).

12. The current sensor according to claim 11, The shielding member has an air gap surrounding the inner circumference of the magnetic core.

13. The current sensor according to any one of claims 10 to 12, The current sensor is a differential current sensor or a sum current sensor with two or more primary conductors.

14. A magnetic core for a current sensor, the magnetic core comprising: The first core (31) and the second core (32), each of the cores comprising a stack of multiple metal sheets; The second core (32) has a first end piece (320) configured such that the metal sheet layer has some longer metal sheets that protrude from the remaining shorter metal sheets. The first core (31) has a second end piece (310), which is constructed in the opposite manner to the first end piece (320) of the second core (32). The first core (31) and the second core (32) are joined together at the connection point such that the longer metal sheet layers of the first end piece (320) and the second end piece (310) overlap at the connection point; and The proportion of the total cross-sectional area of ​​the longer metal sheet of the first end piece (320) in the total cross-sectional area of ​​all metal sheets is less than 40%.

15. The magnetic core according to claim 14, The metal sheet layer forms an irregular comb-like structure in the first end piece (320).

16. A magnetic core for a current sensor, the magnetic core comprising: The first core (31) and the second core (32), each of the cores comprising a stack of multiple metal sheets; The second core (32) has a first end piece (320) configured such that the metal sheet layer has some longer metal sheets, and the remaining shorter metal sheets protrude from the longer metal sheets. The first core (31) has a second end piece (310), which is constructed in the opposite manner to the first end piece (320) of the second core (32). The first core (31) and the second core (32) are joined together at a connection point such that the elongated metal sheets of the first end piece (320) and the second end piece (310) overlap at the connection point; and Each metal sheet in the first end piece (320) and the second end piece (310) forms an irregular comb-like structure.

17. The magnetic core according to claim 16, The longer metal sheets in the first end piece (320) are arranged non-equidistantly.

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