Current sensor

Abstract

The invention relates to a current sensor, and relates to the technical field of current detection. The current sensor comprises a magnetism gathering ring with an opening, a magnetic fluid and an output sampling circuit, the magnetic fluid is arranged at the opening of the magnetism gathering ring, one end of the output sampling circuit is arranged in the magnetic fluid, and a hollow structure of the magnetism gathering ring is used for allowing a conductor to be measured to penetrate through; and the output sampling circuit is used for measuring the current flowing through the conductor to be measured. The current sensor is high in magnetism gathering capability, and can improve the current measurement result.

Description

Technical Field

[0001] The present application relates to the technical field of current detection, and in particular to a current sensor. Background Art

[0002] With the development of modern electric power industry, the requirements for current sensing technology are gradually increasing, especially in the three aspects of large range, high precision and excellent linearity.

[0003] Closed-loop magnetic modulation current sensors are not prone to saturation and have good linearity, and are widely used in the power industry. However, since the magnetic ring of the closed-loop magnetic modulation current sensor has an opening, its magnetic field gathering ability is poor, resulting in inaccurate current measurement results.

[0004] Therefore, there is an urgent need for a current sensor with strong magnetic field gathering ability to improve current measurement results. Summary of the invention

[0005] Based on this, it is necessary to provide a current sensor with strong magnetic field collection ability to improve the current measurement results in response to the above technical problems.

[0006] In a first aspect, the present application provides a current sensor, which includes: a magnetic focusing ring with an opening, a magnetic fluid, and an output sampling circuit, wherein the magnetic fluid is arranged at the opening of the magnetic focusing ring, one end of the output sampling circuit is arranged in the magnetic fluid, and the hollow structure of the magnetic focusing ring is used for a conductor to be measured to pass through;

[0007] The output sampling circuit is used to measure the current flowing through the conductor to be measured.

[0008] In one embodiment, the magnetic fluid includes nano-scale magnetic particles, a base fluid, and a surfactant coated on the nano-scale magnetic solid particles.

[0009] In one embodiment, the output sampling circuit includes: a magnetic modulation chip, an operational amplifier circuit and a current sampling circuit. The magnetic modulation chip is arranged inside the magnetic fluid and is connected to the current sampling circuit through the operational amplifier circuit.

[0010] In one embodiment, the operational amplifier circuit includes an operational amplifier and a power amplifier circuit, the two input terminals of the operational amplifier are respectively connected to the two output terminals of the magnetic modulation chip, the output terminal of the operational amplifier is connected to the input terminal of the power amplifier circuit, and the output terminal of the power amplifier circuit is connected to the current sampling circuit.

[0011] In one embodiment, the power amplifier circuit includes a first triode and a second triode, the source of the first triode is connected to the source of the second triode, the drain of the first triode is connected to the positive electrode of the power supply, the gate of the first triode and the gate of the second triode are both connected to the output end of the operational amplifier, and the drain of the second triode is connected to the negative electrode of the power supply.

[0012] In one embodiment, the current sampling circuit includes a current feedback wire and a sampling resistor, wherein a first end of the current feedback wire is connected to an output end of the operational amplifier circuit, a second end of the current feedback wire is connected to a first end of the sampling resistor, and a second end of the sampling resistor is grounded;

[0013] The current feedback wire is wound on the magnetic focusing ring.

[0014] In one of the embodiments, the number of turns of the current feedback wire on the magnetic focusing ring is determined according to the magnetic focusing ring.

[0015] In one embodiment, the first end of the current feedback wire is wound from the inside of the magnetic focusing ring to the outside, and the first end of the current feedback wire is close to the magnetic fluid, and the second end of the current feedback wire is far away from the magnetic fluid.

[0016] In one embodiment, the resistance of the sampling resistor is determined based on parameter requirements of the current sensor.

[0017] In one of the embodiments, the magnetic focusing ring is made of an iron-based nanocrystalline alloy.

[0018] The above-mentioned current sensor includes a magnetic ring with an opening, a magnetic fluid and an output sampling circuit. The magnetic fluid is arranged at the opening of the magnetic ring, and one end of the output sampling circuit is arranged in the magnetic fluid. The hollow structure of the magnetic ring is used for the conductor to be measured to pass through; the output sampling circuit is used to measure the current flowing through the conductor to be measured. The current sensor fills the opening of the magnetic ring with magnetic fluid, increases the size of the magnetic field gathered in the magnetic ring, reduces the magnetic leakage phenomenon caused by the air gap generated by the opening of the magnetic ring, enables a small current change to cause a large magnetic field change, increases the measurement accuracy of the current sensor, and makes the hysteresis loop of the current sensor in its linear region, so that its linearity is improved and the noise is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] FIG1 is a schematic diagram of a topological structure of a current sensor in one embodiment;

[0021] FIG2 is a schematic diagram of a topological structure of a current sensor in one embodiment;

[0022] FIG. 3 is a schematic diagram of a topological structure of a current sensor in an embodiment.

[0023] Description of reference numerals:

[0024] 10: Current sensor;

[0025] 11: Magnetic ring;

[0026] 12: Magnetic fluid;

[0027] 13: Output sampling circuit;

[0028] 131: Magnetic modulation chip;

[0029] 132: Operational amplifier circuit;

[0030] 133: current sampling circuit;

[0031] 1321: power amplifier circuit;

[0032] U: operational amplifier;

[0033] Q1: the first transistor;

[0034] Q2: the second transistor;

[0035] 1331: current feedback wire;

[0036] R: sampling resistor;

[0037] 20: Conductor to be measured;

[0038] VCC: power supply. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0042] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0045] Before introducing the technical solution of the present application in detail, a brief introduction to the background technology of the present application is first given.

[0046] Current sensors are measuring instruments that convert measured current signals into voltage signals for output. They are widely used in the field of electrical control. With the development of the modern power industry, the requirements for current sensing technology are gradually increasing, especially in terms of large range, high precision and excellent linearity.

[0047] Traditional current sensors are divided into electromagnetic induction current sensors, resistive voltage divider current sensors 10, transformer current sensors, magnetoresistance effect current sensors, optical fiber current sensors, superconducting quantum interference device current sensors and motor current sensors. Due to cost and accuracy requirements, the current sensors commonly used in the power industry mainly use electromagnetic induction sensors, resistive voltage divider current sensors, transformer current sensors and magnetoresistance effect current sensors. Among them, magnetic modulation current sensors are very popular in the power industry due to their small size, high integration and ability to measure high-frequency current components.

[0048] There are two main structures of magnetic modulation current sensors: open loop and closed loop. The open loop magnetic modulation current sensor is easy to saturate, has low linearity and relatively low accuracy. The closed loop magnetic modulation current sensor 10 is not easy to saturate and has good linearity, but because its magnetic ring has an opening, its magnetic gathering ability is poor, resulting in high hysteresis, poor sensitivity and poor current linearity.

[0049] In response to the problems of the above-mentioned closed-loop magnetic modulation current sensor, the present application provides a current sensor 10, which fills the opening of the magnetic ring 11 with a magnetic fluid 12, thereby increasing the size of the magnetic field gathered in the magnetic ring 11, so that a small current change can cause a large magnetic field change, thereby increasing the measurement accuracy of the current sensor 10, and making the hysteresis loop of the current sensor 10 in its linear region, thereby improving its linearity. Of course, the technical solution provided in the embodiments of the present application is not limited to solving only the above-mentioned problems, and there are other technical effects. For details, please refer to the following embodiment description. Next, the technical solution of the present application is introduced in detail. Next, the specific content of the current sensor 10 is introduced in detail through specific embodiments.

[0050] In one embodiment, as shown in FIG. 1 , a current sensor 10 is provided, the current sensor 10 comprises a magnetic focusing ring 11 having an opening, a magnetic fluid 12 and an output sampling circuit 13, the magnetic fluid 12 is arranged at the opening of the magnetic focusing ring 11, one end of the output sampling circuit 13 is arranged in the magnetic fluid 12, and the hollow structure of the magnetic focusing ring 11 is used for a conductor 20 to be measured to pass through;

[0051] The output sampling circuit 13 is used to measure the current flowing through the conductor 20 to be measured.

[0052] In the embodiment of the present application, if it is necessary to measure the current of the conductor 20 to be measured, the conductor 20 to be measured can be passed through the hollow structure of the magnetic ring 11, that is, the conductor 20 to be measured is in the middle position of the current sensor 10, and at this time, the current sensor 10 can measure the current flowing through the conductor 20 to be measured. The conductor 20 to be measured can be various types of current feedback wires 1331, cables, etc. The direction of the current on the conductor to be measured can be from inside to outside, or from outside to inside.

[0053] The size of the magnetic focusing ring 11 and the size of the opening on the magnetic focusing ring 11 can be related to the processing technology and the measurement parameters required by the current sensor 10. The magnetic focusing ring 11 can be made of an iron-based nanocrystalline alloy. The iron-based nanocrystalline alloy material has a high saturation magnetic induction intensity, a low coercive force, and a high Curie temperature, and is suitable for use as a magnetic ring material. It should be noted that the magnetic focusing ring 11 is a fan-shaped ring, not a circular ring, and there is a gap on the magnetic focusing ring 11, that is, an opening on the magnetic focusing ring 11. The magnetic fluid 12 is arranged at the opening of the magnetic focusing ring 11 made of an iron-based nanocrystalline alloy, that is, the magnetic fluid 12 and the magnetic focusing ring 11 form a complete circular ring, so that the size of the magnetic field gathered in the magnetic focusing ring 11 can be increased.

[0054] In one embodiment, the magnetic fluid 12 is composed of three parts, namely, nano-scale magnetic particles, a base liquid, and a surfactant coated on the nano-scale magnetic solid particles. The magnetic fluid 12 synthesized by the three parts is sealed in the opening position of the magnetic focusing ring 11, so that the magnetic focusing ring 11 is connected from a fan-shaped ring to a circular ring, which can greatly improve the convergence effect of the magnetic focusing ring 11 on the magnetic field.

[0055] The output sampling circuit 13 may include a sampling resistor R, and the voltage across the sampling resistor R is obtained, and the ratio of the voltage across the sampling resistor R to the resistance value of the sampling resistor R is used as the current of the conductor 20 to be measured. Alternatively, in addition to the sampling resistor R, in order to improve the detection capability of the output sampling circuit 13 for smaller currents, an operational amplifier circuit 132 may be added to the output sampling circuit 13, and the operational amplifier circuit 132 is arranged between the magnetic fluid 12 and the sampling resistor R. In the process of voltage acquisition, the collected voltage signal is first amplified by the operational amplifier circuit 132, and then the voltage signal acting on the two ends of the sampling resistor R is the amplified voltage signal. The current of the conductor 20 to be measured calculated by the voltage signal is also the amplified current, and then the current value actually flowing through the conductor 20 to be measured is calculated based on the amplification factor and the calculated current of the conductor 20 to be measured.

[0056] The above-mentioned current sensor 10 comprises a magnetic focusing ring 11 with an opening, a magnetic fluid 12 and an output sampling circuit 13. The magnetic fluid 12 is arranged at the opening of the magnetic focusing ring 11, one end of the output sampling circuit 13 is arranged in the magnetic fluid 12, and the hollow structure of the magnetic focusing ring 11 is used for the conductor 20 to be measured to pass through; the output sampling circuit 13 is used to measure the current flowing through the conductor 20 to be measured. The current sensor 10 fills the opening of the magnetic focusing ring 11 with the magnetic fluid 12, increases the size of the magnetic field gathered in the magnetic focusing ring 11, reduces the magnetic leakage phenomenon caused by the air gap generated by the opening of the magnetic focusing ring 11, enables a small current change to cause a large magnetic field change, increases the measurement accuracy of the current sensor 10, and makes the hysteresis loop of the current sensor 10 in its linear region, so that its linearity is improved and the noise is reduced.

[0057] In the process of measuring the current of the conductor 20 to be measured, the current sensor 10 mainly relies on the output sampling circuit 13 to analyze the current flowing through the conductor 20 to be measured. Then, in one embodiment, referring to FIG. 2 , the output sampling circuit 13 includes: a magnetic modulation chip 131, an operational amplifier circuit 132 and a current sampling circuit 133. The magnetic modulation chip 131 is arranged inside the magnetic fluid 12 and is connected to the current sampling circuit 133 through the operational amplifier circuit 132.

[0058] If the current in the conductor 20 to be measured is small, the voltage signal to be measured needs to be amplified before current measurement. Therefore, the output sampling circuit 13 is provided with a magnetic modulation chip 131, an operational amplifier circuit 132 and a current sampling circuit 133.

[0059] In the embodiment of the present application, the magnetic modulation chip 131 is also arranged at the opening of the magnetic focusing ring 11, and the magnetic modulation chip 131 is embedded in the magnetic fluid 12, that is, the magnetic modulation chip 131 is wrapped by the magnetic fluid 12. The output end of the magnetic modulation chip 131 is connected to the input end of the operational amplifier circuit 132, the output end of the operational amplifier circuit 132 is connected to the input end of the current sampling circuit 133, and the output end of the current sampling circuit 133 outputs the current flowing through the conductor 20 to be measured.

[0060] Among them, the magnetic modulation chip 131 can be made of materials that have a magnetic modulation effect on magnetic field transformation, so that the magnetic modulation chip 131 has good performance in terms of signal-to-noise ratio, resolution, etc. It is mainly used to measure the current of the conductor 20 to be measured in the hollow structure where the magnetic focusing ring 11 is set, and convert the current into a voltage signal and transmit it to the operational amplifier circuit 132. The operational amplifier circuit 132 can be adjusted in type and size according to the selection of the magnetic modulation chip 131, and it is mainly used to amplify the voltage signal obtained by converting the current of the conductor 20 to be measured.

[0061] The output sampling circuit 13 includes: a magnetic modulation chip 131, an operational amplifier circuit 132 and a current sampling circuit 133. The magnetic modulation chip 131 is arranged inside the magnetic fluid 12 and is connected to the current sampling circuit 133 through the operational amplifier circuit 132. By arranging the magnetic modulation chip 131 in the output sampling circuit 13, the current of the conductor 20 to be measured can be accurately collected, so that the current accuracy of the magnetic modulation chip 131 corresponding to the measurement can be further increased, and the linearity can be further improved. And converted into a voltage signal, and then the voltage signal is amplified by the operational amplifier circuit 132, so that the current sampling circuit 133 can measure the smaller current flowing through the conductor 20 to be measured, thereby expanding the sampling range of the current sensor 10.

[0062] The operational amplifier circuit 132 in the output sampling circuit 13 is mainly used to amplify the voltage signal obtained by the magnetic modulation chip 131, so as to accurately measure the current of the conductor 20 to be measured later. Next, the specific content of the operational amplifier circuit 132 is described through an embodiment. As shown in FIG3 , the operational amplifier circuit 132 includes an operational amplifier U and a power amplifier circuit 1321. The two input terminals of the operational amplifier U are respectively connected to the two output terminals of the magnetic modulation chip 131, the output terminal of the operational amplifier U is connected to the input terminal of the power amplifier circuit 1321, and the output terminal of the power amplifier circuit 1321 is connected to the current sampling circuit 133.

[0063] In the embodiment of the present application, in order to realize the amplification of the voltage signal, it can be realized by an operational amplifier U and a power amplifier circuit 1321. The operational amplifier U can be a common operational amplifier U, and the non-inverting input terminal and the reverse input terminal of the operational amplifier U are both connected to the output terminal of the magnetic modulation chip 131, and the output terminal of the operational amplifier U is connected to the input terminal of the power amplifier circuit 1321.

[0064] It should be noted that the amplification factor of the operational amplifier U can be realized by the resistance value of the resistor set on the operational amplifier U. For example, a resistor can be set between the in-phase input terminal and the reverse input terminal of the operational amplifier U and the two output terminals of the magnetic modulation chip 131, and a resistor can be set between the reverse input terminal and the output terminal of the operational amplifier U. The output terminal of the power amplifier circuit 1321 is connected to the current sampling circuit 133, which is essentially to further amplify the voltage signal output by the operational amplifier U, and it can include at least two transistors.

[0065] The operational amplifier circuit 132 includes an operational amplifier U and a power amplifier circuit 1321. The two input terminals of the operational amplifier U are respectively connected to the two output terminals of the magnetic modulation chip 131, the output terminal of the operational amplifier U is connected to the input terminal of the power amplifier circuit 1321, and the output terminal of the power amplifier circuit 1321 is connected to the current sampling circuit 133. In the process of amplifying the voltage signal, the voltage signal is first amplified by the operational amplifier U, and then the voltage signal output by the operational amplifier U is further amplified by the power amplifier circuit 1321, which can improve the amplification processing accuracy of the voltage signal.

[0066] Next, the specific contents of the power amplifier circuit 1321 are introduced in detail through an embodiment. Continuing to refer to Figure 3, the power amplifier circuit 1321 includes a first transistor Q1 and a second transistor Q2. The source of the first transistor Q1 is connected to the source of the second transistor Q2, the drain of the first transistor Q1 is connected to the positive electrode of the power supply VCC, the gate of the first transistor Q1 and the gate of the second transistor Q2 are both connected to the output end of the operational amplifier U, and the drain of the second transistor Q2 is connected to the negative electrode of the power supply VCC.

[0067] The first transistor Q1 may be an NPN transistor, and the second transistor Q2 may be a PNP transistor. The power supply VCC may be a 12V power supply, and the positive electrode of the power supply VCC is the +12V power supply, and the negative electrode of the power supply VCC is the -12V power supply.

[0068] In the embodiment of the present application, referring to FIG3, when a current flows through the conductor 20 to be measured, and the current direction is the same as the current direction in FIG3, the magnetic field collecting ring 11 will generate a clockwise magnetic field, which is collected by the magnetic modulation chip 131 and output to the operational amplifier circuit 132, so that the output of the operational amplifier circuit 132 generates a high level, and the high level drives the power amplifier circuit 1321. Specifically, in the power amplifier circuit 1321, the first transistor Q1 is in the on state, and the second transistor Q2 is in the off state, so that the power amplifier circuit 1321 outputs a +12V voltage, which is added to the current feedback wire 1331 and the sampling resistor R behind, so that a current from +12V to the ground is generated in the current feedback wire 1331, and the current will induce a counterclockwise magnetic field in the magnetic field collecting ring 11, which will offset the clockwise magnetic field generated by the current in the conductor 20 to be measured, so that the magnetic field forms a closed loop.

[0069] When current flows through the conductor 20 to be measured, but the current direction is opposite to the current direction in FIG3 , a counterclockwise magnetic field is generated in the magnetic focusing ring 11. After the magnetic field is collected by the magnetic modulation chip 131, it is output to the operational amplifier circuit 132, so that the output of the operational amplifier circuit 132 generates a low level, and the low level drives the power amplifier circuit 1321. Specifically, in the power amplifier circuit 1321, the first transistor Q1 is in the off state, and the second transistor Q2 is in the on state, so that the power amplifier circuit 1321 outputs a -12V voltage, which is added to the current feedback wire 1331 and the sampling resistor R behind, so that a current from the ground to -12V is generated in the current feedback wire 1331, and the current will induce a clockwise magnetic field in the magnetic ring, which offsets the counterclockwise magnetic field generated by the current in the measured current feedback wire 1331, so that the magnetic field forms a closed loop.

[0070] That is to say, the current direction of the conductor 20 to be measured is different, and the conduction directions of the first transistor Q1 and the second transistor Q2 are completely opposite. Under the above two current directions, the negative feedback method of the magnetic field can further reduce the magnetic field, making it more difficult to achieve magnetic saturation. In addition, the current can also change the original current signal into a voltage signal by generating a voltage drop on the sampling resistor R, so that the current signal can be measured non-contactly by measuring the voltage of the sampling resistor R in the current sensor 10.

[0071] The power amplifier circuit 1321 includes a first transistor Q1 and a second transistor Q2, wherein the source of the first transistor Q1 is connected to the source of the second transistor Q2, the drain of the first transistor Q1 is connected to the positive electrode of the power supply VCC, the gate of the first transistor Q1 and the gate of the second transistor Q2 are both connected to the output end of the operational amplifier U, and the drain of the second transistor Q2 is connected to the negative electrode of the power supply VCC. The power amplifier circuit 1321 controls the on and off of the first transistor Q1 and the second transistor Q2 when the current direction of the conductor 20 to be measured is different, so as to amplify the voltage signal, thereby accurately measuring the current of the conductor 20 to be measured.

[0072] The above embodiments are all detailed descriptions of the operational amplifier circuit 132 in the output sampling circuit 13. Next, the current sampling circuit 133 in the output sampling circuit 13 is described in detail. With reference to FIG3 , the current sampling circuit 133 includes a current feedback wire 1331 and a sampling resistor R. The first end of the current feedback wire 1331 is connected to the output end of the operational amplifier circuit 132, the second end of the current feedback wire 1331 is connected to the first end of the sampling resistor R, and the second end of the sampling resistor R is grounded.

[0073] The current feedback wire 1331 is wound on the magnetic focusing ring 11 .

[0074] Among them, the number of turns of the current feedback wire 1331 on the magnetic ring 11 is determined according to the magnetic ring 11, and the first end of the current feedback wire 1331 is wound from the inside to the outside of the magnetic ring 11, and the first end of the current feedback wire 1331 is close to the magnetic fluid 12, and the second end of the current feedback wire 1331 is far away from the magnetic fluid 12.

[0075] Continuing to refer to FIG3 , the number of turns of the current feedback wire 1331 wound on the magnetic focusing ring 11 can be adjusted according to the selection of the magnetic modulation chip 131, and the size and winding direction of the current feedback wire 1331 need to be wound according to the display in FIG3 . The current feedback wire 1331 is used to feedback the current of the conductor 20 to be measured after amplification.

[0076] As can be seen from the figure, the first end of the current feedback wire 1331 is connected to the common end of the first transistor Q1 and the second transistor Q2, and is wound from the inside to the outside in sequence from the position close to the magnetic fluid 12 on the magnetic focusing ring 11. After winding, it is connected to the first end of the sampling resistor R, and the second end of the sampling resistor R is grounded.

[0077] It should be noted that the resistance of the sampling resistor R is determined based on the parameter requirements of the current sensor 10, that is, the resistance of the sampling resistor R can be changed. For example, a sliding rheostat can be used to change the resistance of the sampling resistor R, or the resistance of the sampling resistor R can be changed by replacing the sampling resistors R with different resistance values.

[0078] The above-mentioned current sampling circuit 133 includes a current feedback wire 1331 and a sampling resistor R. The first end of the current feedback wire 1331 is connected to the output end of the operational amplifier circuit 132, the second end of the current feedback wire 1331 is connected to the first end of the sampling resistor R, and the second end of the sampling resistor R is grounded; the current feedback wire 1331 is wound on the magnetic focusing ring 11. In the current sampling circuit 133, the current of the conductor 20 to be measured after the amplification process is fed back through the current feedback wire 1331, and by obtaining the voltage V0 across the sampling resistor R, the amplified voltage can be obtained, and then by mapping the amplification factor, the current flowing through the conductor 20 to be measured can be accurately obtained.

[0079] In a specific embodiment, still referring to FIG. 3 , the current sensor 10 includes: a magnetic focusing ring 11 with an opening, a magnetic fluid 12, a magnetic modulation chip 131, an operational amplifier U, a first transistor Q1, a second transistor Q2, a current feedback wire 1331 and a sampling resistor R, wherein the magnetic fluid 12 is disposed at the opening of the magnetic focusing ring 11, and the hollow structure of the magnetic focusing ring 11 is used for the conductor 20 to be measured to pass through;

[0080] The magnetic modulation chip 131 is arranged inside the magnetic fluid 12, and the two output ends of the magnetic modulation chip 131 are connected to the in-phase input end and the inverting input end of the operational amplifier U, the output end of the operational amplifier U is respectively connected to the gates of the first transistor Q1 and the second transistor Q2, and the source of the first transistor Q1 is connected to the source of the second transistor Q2, the drain of the first transistor Q1 is connected to the positive electrode of the power supply VCC, and the drain of the second transistor Q2 is connected to the negative electrode of the power supply VCC;

[0081] The common end of the first transistor Q1 and the second transistor Q2 is connected to the input end of the current feedback wire 1331, the second end of the current feedback wire 1331 is connected to the first end of the sampling resistor R, and the second end of the sampling resistor R is grounded;

[0082] The current feedback wire 1331 is wound on the magnetic focusing ring 11 , and the first end of the current feedback wire 1331 is wound from the inside of the magnetic focusing ring 11 to the outside, and the first end of the current feedback wire 1331 is close to the magnetic fluid 12 , and the second end of the current feedback wire 1331 is far away from the magnetic fluid 12 .

[0083] The above content is a further detailed description of the embodiments of the present application in combination with specific / preferred implementation methods, and it cannot be determined that the specific implementation of the embodiments of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the embodiments of the present application belong, without departing from the concept of the embodiments of the present application, it can also make several substitutions or modifications to these described implementation methods, and these substitutions or modifications should be regarded as belonging to the protection scope of the embodiments of the present application. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered as the scope recorded in this specification.

[0084] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0085] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A current sensor, characterized in that: The current sensor comprises: a magnetic focusing ring with an opening, a magnetic fluid and an output sampling circuit, wherein the magnetic fluid is arranged at the opening of the magnetic focusing ring, one end of the output sampling circuit is arranged in the magnetic fluid, and the hollow structure of the magnetic focusing ring is used for the conductor to be measured to pass through; The output sampling circuit is used to measure the current flowing through the conductor to be measured.

2. The current sensor according to claim 1, characterized in that: The magnetic fluid comprises nano-scale magnetic particles, a base liquid and a surfactant coated on the nano-scale magnetic solid particles.

3. The current sensor according to claim 1 or 2, characterized in that: The output sampling circuit includes: a magnetic modulation chip, an operational amplifier circuit and a current sampling circuit. The magnetic modulation chip is arranged inside the magnetic fluid and is connected to the current sampling circuit through the operational amplifier circuit.

4. The current sensor according to claim 3, characterized in that: The operational amplifier circuit includes an operational amplifier and a power amplifier circuit, the two input ends of the operational amplifier are respectively connected to the two output ends of the magnetic modulation chip, the output end of the operational amplifier is connected to the input end of the power amplifier circuit, and the output end of the power amplifier circuit is connected to the current sampling circuit.

5. The current sensor according to claim 4, characterized in that: The power amplifier circuit includes a first transistor and a second transistor, the source of the first transistor is connected to the source of the second transistor, the drain of the first transistor is connected to the positive electrode of the power supply, the gate of the first transistor and the gate of the second transistor are both connected to the output end of the operational amplifier, and the drain of the second transistor is connected to the negative electrode of the power supply.

6. The current sensor according to claim 3, characterized in that: The current sampling circuit comprises a current feedback wire and a sampling resistor, wherein a first end of the current feedback wire is connected to an output end of the operational amplifier circuit, a second end of the current feedback wire is connected to a first end of the sampling resistor, and a second end of the sampling resistor is grounded; The current feedback wire is wound on the magnetic focusing ring.

7. The current sensor according to claim 6, characterized in that: The number of turns of the current feedback wire on the magnetic focusing ring is determined according to the magnetic focusing ring.

8. The current sensor according to claim 6, characterized in that: The first end of the current feedback wire is wound outward from the inside of the magnetic focusing ring, and the first end of the current feedback wire is close to the magnetic fluid, and the second end of the current feedback wire is far away from the magnetic fluid.

9. The current sensor according to claim 6, characterized in that: The resistance value of the sampling resistor is determined based on parameter requirements of the current sensor.

10. The current sensor according to claim 1 or 2, characterized in that: The magnetic focusing ring is made of iron-based nanocrystalline alloy.

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