Fluxgate current sensor iron core structure

Abstract

The present invention provides a fluxgate current sensor core structure. The core of the negative feedback circuit includes a core frame; the core frame is formed by stacking a plurality of iron core sheets along the flow direction of the measured current. It can not only reduce the heat generation of the negative feedback core and improve the overall performance stability of the sensor during high-frequency current testing, but also maximize the anti-external magnetic performance and improve the accuracy of the probe.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a core structure of a fluxgate current sensor. Background Art

[0002] Please refer to Figure 1 , Figure 1 which shows the equivalent schematic diagram of a fluxgate current sensor. Conventionally, a general fluxgate current sensor directly uses a piece of permalloy as the core of the negative feedback circuit. Thus, in the case where the primary measured current is high-frequency, due to the high-frequency eddy magnetic field generated by the primary high-frequency current, it will cause the permalloy core to heat up, affecting the test accuracy; in addition, the core magnetic resistance of the existing fluxgate current sensor is relatively low. In an external magnetic field, a part of the magnetic force lines will pass through the probe of the fluxgate, and the fluxgate is relatively sensitive to the external magnetic field, thus causing the feedback circuit to malfunction, resulting in relatively weak anti-external magnetic performance of the fluxgate current sensor. Summary of the Invention

[0003] In view of the above problems, this application provides a core structure of a fluxgate current sensor, which can reduce the eddy magnetic field and the core heating, and can also increase the magnetic resistance of the feedback magnetic circuit and improve the anti-external magnetic performance.

[0004] To achieve the above object, the inventor provides a fluxgate current sensor, and the core of the negative feedback circuit includes a core frame; the core frame is formed by stacking a plurality of iron chips along the flow direction of the measured current.

[0005] Different from the prior art, the above technical solution designs the core of the negative feedback circuit into a core frame formed by stacking a plurality of iron chips along the flow direction of the measured current, thereby reducing the eddy magnetic field and further reducing the heating.

[0006] In some embodiments, the plurality of iron chips are connected by an adhesive method.

[0007] In some embodiments, the core frame includes a first core and a second core; the first core and the second core enclose the core frame having two through holes; the two through holes communicate with each other.

[0008] In some embodiments, both the first core and the second core are bow-shaped.

[0009] In some embodiments, the probe of the negative feedback circuit is located in one of the through holes of the core frame.

[0010] In some embodiments, the first core and the second core overlap in the through hole without the probe.

[0011] In some embodiments, the core further includes a third core bar; the third core bar is located at the top of the core frame.

[0012] In the above embodiments, by providing the third iron core bar, the magnetic resistance of the feedback magnetic circuit can be increased, and the interference of the external magnetic field on the probe can be reduced.

[0013] In some embodiments, the length of the third iron core does not exceed the top of the iron core frame.

[0014] In some embodiments, an adhesive is provided between the third iron core and the top of the iron core frame.

[0015] In some embodiments, the adhesive corresponds to the top of the first iron core, or the adhesive corresponds to the top of the second iron core, or the adhesive corresponds to the top of the iron core frame.

[0016] The relevant descriptions in the above invention content are only an overview of the technical solutions of this application. In order to enable those of ordinary skill in the art to more clearly understand the technical solutions of this application, and then can be implemented according to the content recorded in the text of the specification and the drawings, and in order to make the above objects, other objects, features and advantages of this application more easily understood, the following is described in conjunction with the specific embodiments of this application and the drawings. Description of the Drawings

[0017] The drawings are only used to illustrate the principles, implementation methods, applications, features, effects, etc. of the specific embodiments of this application and other related contents, and should not be considered as a limitation to this application.

[0018] In the drawings of the specification:

[0019] Figure 1 shows the equivalent schematic diagram of the fluxgate current sensor;

[0020] Figure 2 shows the side view of the iron core frame of the negative feedback circuit in a fluxgate current sensor of an embodiment;

[0021] Figure 3 shows the front view of the iron core frame of a fluxgate current sensor provided in this embodiment;

[0022] Figure 4 (a)-(b) show the left side view and the right side view of the iron core frame of a fluxgate current sensor provided in this embodiment respectively;

[0023] Figure 5 shows the front view of the iron core structure of a fluxgate current sensor of an embodiment Figure 1 ;

[0024] Figure 6 shows the front view of the iron core structure of a fluxgate current sensor of an embodiment Figure 2 ;

[0025] Figure 7 It is a front view of the iron core structure of a fluxgate current sensor showing an embodiment Figure 3 ;

[0026] Figure 8 It is a front view of the iron core structure of a fluxgate current sensor showing an embodiment Figure 4 。

[0027] The reference numerals involved in the above-mentioned drawings are explained as follows:

[0028] 1. Iron core frame; 2. Iron core sheet; 3. First iron core; 4. Second iron core; 5. Through hole;

[0029] 6. Probe; 7. Measured current; 8. Third iron core bar; 9. Top; 10. Adhesive. Specific embodiments

[0030] To illustrate in detail the possible application scenarios, technical principles, specific implementable solutions, achievable purposes and effects of the present application, the following is a detailed description in conjunction with the specific embodiments listed and with reference to the drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and thus are only examples and cannot be used to limit the protection scope of the present application.

[0031] Referring to "embodiment" in this document means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it particularly limited to its independence or relevance to other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0032] Unless otherwise defined, the meanings of the technical terms used in this document are the same as those commonly understood by those skilled in the technical field to which the present application belongs; the use of the relevant terms in this document is only for describing specific embodiments and is not intended to limit the present application.

[0033] In the description of the present application, the phrase "and / or" is an expression used to describe the logical relationship between objects, indicating that there can be three relationships. For example, A and / or B means: there is A, there is B, and there is both A and B at the same time. In addition, the character " / " in this document generally represents an "or" logical relationship between the associated objects before and after.

[0034] In this application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantitative, primary-secondary, or sequential relationship between these entities or operations.

[0035] Without further limitation, in this application, the expressions such as "comprising", "including", "having", or other similar expressions used in a statement are intended to cover non-exclusive inclusion. These expressions do not exclude the possibility that there may be additional elements in the process, method, or product including the said elements. Thus, a process, method, or product including a series of elements may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to this process, method, or product.

[0036] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceeding", etc. are understood not to include the recited number; expressions such as "above", "below", "within", etc. are understood to include the recited number. In addition, in the description of the embodiments of this application, the meaning of "a plurality of" is two or more (including two). Similar expressions related to "multiple", such as "multiple groups", "multiple times", etc., are understood in the same way, unless otherwise specifically defined.

[0037] In the description of the embodiments of this application, spatial-related expressions such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiment or the drawing. This is only for the convenience of describing the specific embodiments of this application or facilitating the understanding of the reader, rather than indicating or implying that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of this application.

[0038] Unless otherwise clearly specified or limited, in the description of the embodiments of this application, expressions such as "installed", "connected", "coupled", "fixed", "set", etc. should be understood in a broad sense. For example, the said "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art to which this application pertains, the specific meaning of the above expressions in the embodiments of this application can be understood according to specific circumstances.

[0039] Please refer toFigure 2 , Figure 2 is a side view of the iron core frame of the negative feedback circuit in a fluxgate current sensor according to an embodiment. As Figure 2 shown, the iron core of the negative feedback circuit in the fluxgate current sensor of this embodiment includes an iron core frame 1; the iron core frame 1 is formed by stacking a plurality of iron core chips 2 along the direction of the measured current.

[0040] Different from directly using a single Permalloy sheet as the iron core in the negative feedback circuit of the prior art, in this embodiment, more than two iron core chips are stacked to obtain the iron core frame through which the measured current flows; since the iron core structure is divided into several sheets, the beneficial effects of reducing the eddy magnetic field and decreasing the iron core heating degree can be obtained.

[0041] Optionally, the plurality of iron core chips can be connected by an adhesive method, or a double-sided adhesive,; preferably connected by an adhesive method to make the Permalloy into a whole.

[0042] Optionally, the material of the iron core chip can be Permalloy or a high-permeability magnetic core material such as silicon steel sheet; preferably Permalloy is used to have a small hysteresis effect and make the zero-drift error of the fluxgate current sensor smaller.

[0043] Optionally, the adhesive can be AB glue or a double-sided adhesive such as brown glue; preferably AB glue is used to facilitate assembly.

[0044] Please refer to Figure 3 and Figure 4 (a)-(b), Figure 3 is a front view of the iron core frame of a fluxgate current sensor provided by this embodiment; Figure 4 (a)-(b) are respectively a left side view and a right side view of the iron core frame of a fluxgate current sensor provided by this embodiment. As Figure 3 shown, on the basis of the Figure 1 embodiment, the specific structure of the iron core frame 1 is further defined:

[0045] The iron core frame 1 includes a first iron core 3 and a second iron core 4; the first iron core 3 and the second iron core 4 enclose the iron core frame having two through holes 5; the two through holes 5 communicate with each other; the probe 6 of the negative feedback circuit is located in one of the through holes of the iron core frame. The left and right side views of the iron core frame 1 of this embodiment are as Figure 4 shown, wherein, Figure 4 (a) is the left side view of the iron core frame, that is, the side view of the second iron core 4; Figure 4 (b) is the right side view of the iron core frame, that is, the side view of the first iron core 3.

[0046] It can be understood that the iron core frame 1 is similar to a gourd-shaped structure. The first iron core 3 and the second iron core 4 can be respectively the left and right parts of the iron core frame 1, or the upper and lower parts, preferably the left and right parts.

[0047] In this embodiment, considering the sensitivity of the probe 6, by designing the iron core into a frame structure with two through holes 5, and placing the probe 6 in one of the through holes, so as to shield the influence of the external magnetic field on the probe as much as possible and improve the anti-external magnetic ability.

[0048] The structures of the first iron core 3 and the second iron core 4 can be diverse, such as bow-shaped, "3"-shaped, etc.

[0049] As a preferred embodiment of this embodiment, as Figure 2 shown, both the first iron core 3 and the second iron core 4 are bow-shaped; in the iron core frame 1 formed by two bow-shaped iron cores, the square through hole above is smaller than the square through hole below; the probe 6 is located in the square through hole above. The iron core frame of this structure can not only reduce the eddy magnetic field based on the segmentation structure and reduce the iron core heating; but also can shield the influence of the external magnetic field on the probe to a certain extent and improve the anti-external magnetic ability.

[0050] Optionally, the first iron core 3 and the second iron core 4 overlap in the through hole without the probe, that is, the lower through hole, as Figure 3 shown. That is, in Figure 3 the top view corresponding to the front view, the lowermost cross bar of the first iron core and the lowermost cross bar of the second iron core overlap in the top view. Such a design can facilitate installation during production.

[0051] Please refer to Figure 5 , Figure 5 which is a front view showing the iron core structure of a fluxgate current sensor in an embodiment Figure 1 . As Figure 5 shown, based on the Figure 2 embodiment, the iron core of this embodiment further includes a third iron core bar 8 to further improve the anti-external magnetic performance.

[0052] Specifically, the third iron core bar 8 is located at the top 9 of the iron core frame 1. That is, on the side close to the probe. The third iron core bar 8 is perpendicular to the direction of the through hole 5 in the iron core frame 1.

[0053] In this embodiment, the setting of the third iron core bar 8 can guide part of the magnetic force lines of the external magnetic field to flow through the third iron core bar 8 in a direction away from the probe 6, so as to reduce the magnetic force lines of the external magnetic field reaching the probe 6 to a certain extent, thereby improving the anti-external magnetic performance.

[0054] In some specific embodiments of this embodiment, the length of the third iron core 8 does not exceed the top 9 of the iron core frame 1. That is, in Figure 5 the top view corresponding to the front view, both ends of the third iron core bar 8 do not exceed the top of the iron core frame. Preferably, as Figure 4 shown, the length of the third iron core bar 8 is equal to the length of the top 9 of the iron core frame 1, so that while maximizing the guidance of the external magnetic field lines away from the probe, the overall structure of the iron core can be made more regular.

[0055] Please refer to Figures 6 to 8 , Figure 6 which is a front view showing the iron core structure of a fluxgate current sensor according to an embodiment; Figure 2 ; Figure 7 which is a front view showing the iron core structure of a fluxgate current sensor according to an embodiment; Figure 3 ; Figure 8 which is a front view showing the iron core structure of a fluxgate current sensor according to an embodiment. Figure 4 . As Figures 6 to 8 shown, on the basis of Figure 5 the embodiment, an adhesive 10 is added between the third iron core bar 8 and the top 9 of the iron core frame 1. By means of the adhesive 10, the magnetic resistance of the negative feedback magnetic circuit is increased, and based on the bypass principle of the external magnetic field, the magnetic field lines reaching the probe are further reduced, thereby further improving the anti-external magnetic ability of the fluxgate.

[0056] Specifically, for the fluxgate current sensor of this embodiment, an adhesive 10 is also provided between the third iron core bar 8 and the top 9 of the iron core frame 1 to form an adhesive layer in the iron core.

[0057] Optionally, the adhesive 10 can be a cloth tape or a thin sheet of non-magnetic material; preferably a cloth tape such as 3M Mylar coil tape.

[0058] There are various specific distribution methods of the adhesive:

[0059] As an optional specific embodiment, as Figure 6 shown, the adhesive 10 corresponds to the top of the first iron core 3, that is, the adhesive layer completely covers the top of the first iron core 3.

[0060] As an optional specific embodiment, as Figure 7 shown, the adhesive 10 corresponds to the top of the second iron core 4, that is, the adhesive layer completely covers the top of the second iron core 4.

[0061] As a preferred specific embodiment, as Figure 8 shown, the adhesive 10 corresponds to the top 9 of the iron core frame 1, that is, the adhesive layer completely covers the entire top 9 of the iron core frame 1.

[0062] All the above specific distribution methods of the adhesive layer can increase the magnetic resistance of the negative feedback magnetic circuit, thereby further reducing the magnetic force lines of the external magnetic field reaching the probe on the basis of the Figure 5 embodiment, and further improving the performance of resisting external magnetism. Among them, the above preferred specific embodiments will achieve the best results.

[0063] Optionally, the thickness of the adhesive layer is 0.1-0.5 mm.

[0064] Next, the present embodiment is verified by magnetic force intensity calculation:

[0065] A part of the external magnetic field Bin passes through the third iron core strip, and this part of the magnetic induction intensity is denoted as Bout. Another part reaches the gap and then reaches the probe, resulting in malfunction. This part of the magnetic induction intensity is denoted as Boffset. It can be understood that Figures 6 to 8 in the external magnetic field Bin, the magnetic induction intensity of the part with the upper arrow is Bout; the magnetic induction intensity of the part with the lower arrow is Boffset. Let the number of magnetic force lines of the first iron core, the second iron core and the third iron core strip be Nin, Nout and Noffset respectively; let the cross-sectional areas be Sin, Sout and Snotape respectively. Then Bin = Bout + Boffset;

[0066] Therefore, when the adhesive layer is not provided, Boffset_notape = Noffset / Snotape;

[0067] When the adhesive layer is provided, Boffset_havetape = Noffset / (Snotape + Stape);

[0068] Boffset_havetape - Boffset_notape = Noffset * (-Stape / Snotape^2);

[0069] It can be obtained from the above formula that when the cross-sectional area thickness of the iron core is 0.5 mm and the thickness of the adhesive layer is 0.1 mm, the malfunction caused by the external magnetic field will be significantly reduced; the best thickness of the adhesive tape is between 0.1 mm and 0.5 mm.

[0070] It can be seen that the setting of the adhesive layer can further increase the magnetic resistance of the feedback magnetic circuit compared with the case where the adhesive layer is not provided, reduce the influence of the magnetic force lines of the external magnetic field passing through the probe on the accuracy of the probe, and thus improve the anti-external magnetic ability.

[0071] The fluxgate current sensor provided by the present invention can not only reduce the heating of the negative feedback iron core and improve the overall performance stability of the sensor during high-frequency current testing; but also can maximize the anti-external magnetic performance and improve the accuracy of the probe.

[0072] Finally, it should be noted that although the above embodiments have been described in the text and drawings of the specification of the present application, the patent protection scope of the present application cannot be limited thereby. Any technical solution obtained by equivalent structure or equivalent process substitution or modification based on the substantial concept of the present application and using the content recorded in the text and drawings of the specification of the present application, as well as any technical solution directly or indirectly implemented in other related technical fields by the technical solutions of the above embodiments, are all included in the patent protection scope of the present application.

Claims

1. A core structure of a fluxgate current sensor, characterized in that, The iron core of the negative feedback circuit includes an iron core frame; the iron core frame is formed by stacking a plurality of iron core sheets along the flow direction of the measured current; The plurality of iron core sheets are connected by an adhesive method; The iron core frame includes a first iron core and a second iron core; the first iron core and the second iron core enclose the iron core frame with two through holes; the two through holes communicate with each other; the probe of the negative feedback circuit is located in one of the through holes of the iron core frame; the first iron core and the second iron core overlap in the through hole without the probe; the iron core further includes a third iron core strip; the third iron core strip is located at the top of the iron core frame.

2. The core structure of a fluxgate current sensor according to claim 1, characterized in that, Both the first iron core and the second iron core are bow-shaped.

3. The core structure of a fluxgate current sensor according to claim 1, characterized in that, The length of the third iron core does not exceed the top of the iron core frame.

4. The core structure of a fluxgate current sensor according to claim 1, characterized in that, An adhesive is provided between the third iron core and the top of the iron core frame.

5. The core structure of a fluxgate current sensor according to claim 4, characterized in that, The adhesive corresponds to the top of the first iron core, or the adhesive corresponds to the top of the second iron core, or the adhesive corresponds to the top of the iron core frame.

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