CN220137256U - Hall type high-precision open-loop current sensor - Google Patents

Abstract

The utility model relates to a Hall type high-precision open-loop current sensor. The utility model comprises a shell, wherein the shell is internally provided with: the magnetic core comprises a first magnetic core arm, a second magnetic core arm and a third magnetic core arm which is respectively connected with the first magnetic core arm and the second magnetic core arm, and a containing space suitable for penetration of a current wire to be detected is formed among the first magnetic core arm, the second magnetic core arm and the third magnetic core arm; the Hall chip is arranged in the accommodating space, a first gap is reserved between the Hall chip and the first magnetic core arm, a second gap is reserved between the Hall chip and the second magnetic core arm, and a third gap is reserved between the Hall chip and the third magnetic core arm. The utility model ensures that the magnetic field gathered by the magnetic core can be efficiently transmitted to the Hall chip, and ensures the high precision and the high linearity of the product.

Description

Hall type high-precision open-loop current sensor

Technical Field

The utility model relates to the technical field of current sensors, in particular to a Hall type high-precision open-loop current sensor.

Background

The open-loop Hall current sensor adopts a Hall effect principle, and the closed-loop Hall current sensor adopts a magnetic balance principle. The response time and accuracy of the closed loop is much better than that of the open loop. The open loop and the closed loop can monitor alternating current, the open loop is generally suitable for large current monitoring, and the closed loop is suitable for small current monitoring. The device has the advantages of small packaging size, wide measuring range, light weight, low power loss and the like.

The working process of the open-loop Hall sensor without insertion loss comprises the following steps: when the primary current (Ip) passes through a wire, a magnetic field is generated around the wire, the magnitude of the magnetic field is proportional to the current flowing through the wire, and the magnetic field is gathered by the magnetic core to be induced on the linear Hall device and is provided with a signal output. The signal is amplified by the signal amplifier and then directly output, and the output condition of the primary side current is accurately reflected by the signal output by the Hall device.

The working process of the closed-loop Hall current sensor comprises the following steps: when magnetic flux generated by the primary current IP is concentrated in the magnetic circuit through the magnetic core, the Hall device is fixed in the air gap to detect the magnetic flux, and a reverse compensation current is output through a plurality of coils wound on the magnetic core and used for counteracting the magnetic flux generated by the primary current (IP), so that the magnetic flux in the magnetic circuit is always kept to be zero. The secondary side compensation current generated by the Hall element (sensitive element) and the auxiliary circuit accurately reflects the primary side current. The output end of the sensor can output current change which accurately reflects primary side current after the processing of a special circuit.

The fluxgate sensor is a sensor for measuring a weak magnetic field by utilizing the nonlinear relation between the magnetic induction intensity and the magnetic field intensity of a high-permeability iron core in a measured magnetic field under the saturated excitation of an alternating magnetic field. The fluxgate sensor is a magnetic measuring device which is manufactured by using certain soft magnetic materials with high magnetic permeability (such as permalloy) as a magnetic core and using the subsaturation characteristic of the soft magnetic materials under the action of an alternating magnetic field and the Faraday electromagnetic induction principle. The structure of the transformer can be seen as a special transformer, and the fluxgate magnetic measurement method is to utilize the magnetic core of the special transformer, when alternating current flows through the primary coil of the transformer, the magnetic core is magnetized by alternating supersaturation excitation repeatedly, when an external magnetic field exists, the excitation becomes asymmetric, and the output signal of the transformer is modulated by the external magnetic field. The measurement of the external magnetic field can be realized by detecting the output modulation signal. The output of the fluxgate probe is mainly the second harmonic of the excitation signal, and measurement data are needed to be obtained through processing. The fluxgate sensor has the characteristics of high resolution, wide and reliable measuring weak magnetic field range, capability of directly measuring the component of the magnetic field, suitability for being used in a variable speed motion system and the like.

The existing open loop current sensor has some defects, and the defects are mainly expressed in the following three aspects:

first, the accuracy is not high. The accuracy of an open loop current sensor is affected by a variety of factors, such as the nonlinearity of the magnetic core, the temperature drift of the hall element, the noise of the circuit, etc. These factors can lead to errors and distortions in the output signal, reducing the accuracy and reliability of the measurement. To improve accuracy, the magnetic core and hall element need to be calibrated and compensated, adding complexity and cost to design and manufacture.

Second, the weak magnetic core focusing capability affects the sensitivity. The sensitivity of an open loop current sensor refers to the rate of change of the output signal with respect to the input current, which reflects the measurement range and resolution of the sensor. The sensitivity is related to the polymagnetic ability of the core, the stronger the polymagnetic ability, the higher the sensitivity. However, the saturation magnetic flux density of the magnetic core material of the existing open loop current sensor is low, resulting in weak polymagnetic capability. When the input current is larger, the magnetic core is easy to enter a saturated state, so that the output signal loses a linear relation, and the sensitivity is reduced.

Third, ferrite cores have poor low temperature characteristics. Ferrite is a common soft magnetic material and has the advantages of low cost, good frequency response, strong anti-interference capability and the like. However, ferrite has some disadvantages, one of which is poor low temperature characteristics. When the temperature decreases, the initial permeability of the ferrite may drastically decrease, resulting in a decrease in the amplitude of the output signal. This is a serious problem for open loop current sensors operating in low temperature environments, affecting their measurement performance and stability.

Disclosure of Invention

Therefore, the utility model aims to solve the technical problems that the open loop current sensor in the prior art has low precision, the magnetic core has weak magnetic focusing capability to influence the sensitivity and the ferrite magnetic core has poor low-temperature characteristic.

In order to solve the technical problems, the utility model provides a Hall type high-precision open-loop current sensor, which comprises a shell, wherein the shell is internally provided with:

the magnetic core comprises a first magnetic core arm, a second magnetic core arm and a third magnetic core arm which is respectively connected with the first magnetic core arm and the second magnetic core arm, and a containing space suitable for penetration of a current wire to be detected is formed among the first magnetic core arm, the second magnetic core arm and the third magnetic core arm;

the Hall chip is arranged in the accommodating space, a first gap is reserved between the Hall chip and the first magnetic core arm, a second gap is reserved between the Hall chip and the second magnetic core arm, and a third gap is reserved between the Hall chip and the third magnetic core arm.

In one embodiment of the present utility model, the first magnetic core arm and the second magnetic core arm are disposed in parallel, and the third magnetic core arm is disposed perpendicular to the first magnetic core arm and the second magnetic core arm, respectively.

In one embodiment of the present utility model, a first arc chamfer is formed between the first magnetic core arm and the third magnetic core arm, and a second arc chamfer is formed between the second magnetic core arm and the third magnetic core arm.

In one embodiment of the utility model, the magnetic core is a manganese zinc ferrite core.

In one embodiment of the present utility model, the first gap and the second gap are equal.

In one embodiment of the utility model, the third gap is larger than the first gap and the second gap.

In one embodiment of the utility model, the first gap and/or the second gap is 0.55±0.05mm.

In one embodiment of the present utility model, the third gap is 4.5±0.1mm.

In one embodiment of the utility model, the height of the magnetic core is 9.6±0.15mm.

In one embodiment of the utility model, the thickness of the core is 6.2±0.15mm.

Compared with the prior art, the technical scheme of the utility model has the following advantages:

according to the Hall type high-precision open-loop current sensor, the magnetic field gathered by the magnetic core can be efficiently transmitted to the Hall chip, and finally, a voltage signal in linear relation with the input current is output, so that the high precision and the high linearity of a product are ensured. The problems that the existing open-loop current sensor is low in precision, the magnetic core is weak in magnetic focusing capability, sensitivity is affected, and the ferrite magnetic core is poor in low-temperature characteristic are solved.

Drawings

In order that the utility model may be more readily understood, a more particular description of the utility model will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings.

FIG. 1 is a schematic view of the sensor of the present utility model.

Fig. 2 is a cross-sectional view taken along A-A in fig. 1.

Fig. 3 is a 3D magnetic field simulation model diagram.

Fig. 4 is a magnetic field profile of an xy section.

Fig. 5 is a magnetic field flow direction distribution diagram of xy section.

Fig. 6 is a magnetic field coordinate graph.

Description of the specification reference numerals:

1. a housing;

2. a magnetic core; 21a, a first magnetic core arm; 21b, a second magnetic core arm; 21c, a third magnetic core arm; 22. an accommodating space; 23a, a first arc chamfer; 23b, a second arc chamfer;

3. a Hall chip; 31a, a first gap; 31b, a second gap; 31c, third gap.

Detailed Description

The present utility model will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the utility model and practice it.

In the present utility model, if directions (up, down, left, right, front and rear) are described, they are merely for convenience of description of the technical solution of the present utility model, and do not indicate or imply that the technical features must be in a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the present utility model, "a plurality of" means one or more, and "a plurality of" means two or more, and "greater than", "less than", "exceeding", etc. are understood to not include the present number; "above", "below", "within" and the like are understood to include this number. In the description of the present utility model, the description of "first" and "second" if any is used solely for the purpose of distinguishing between technical features and not necessarily for the purpose of indicating or implying a relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the present utility model, unless clearly defined otherwise, terms such as "disposed," "mounted," "connected," and the like should be construed broadly and may be connected directly or indirectly through an intermediate medium, for example; the connecting device can be fixedly connected, detachably connected and integrally formed; can be mechanically connected, electrically connected or capable of communicating with each other; may be a communication between two elements or an interaction between two elements. The specific meaning of the words in the utility model can be reasonably determined by a person skilled in the art in combination with the specific content of the technical solution.

Referring to fig. 1 to 2, the hall type high-precision open-loop current sensor of the present utility model comprises a housing 1, wherein the housing 1 is internally provided with:

a magnetic core 2, where the magnetic core 2 includes a first magnetic core arm 21a, a second magnetic core arm 21b, and a third magnetic core arm 21c connected to the first magnetic core arm 21a and the second magnetic core arm 21b, and a receiving space 22 suitable for a current wire to be detected to pass through is formed between the first magnetic core arm 21a, the second magnetic core arm 21b, and the third magnetic core arm 21 c;

the hall chip 3 is disposed in the accommodating space 22, a first gap 31a (D1 in fig. 2) is left between the hall chip 3 and the first magnetic core arm 21a, a second gap 31b (D2 in fig. 2) is left between the hall chip 3 and the second magnetic core arm 21b, and a third gap 31c (D3 in fig. 2) is left between the hall chip 3 and the third magnetic core arm 21 c.

Specifically, the first magnetic core arm 21a and the second magnetic core arm 21b are disposed in parallel, and the third magnetic core arm 21c is disposed perpendicular to the first magnetic core arm 21a and the second magnetic core arm 21b, respectively.

Specifically, a first circular arc chamfer 23a is formed between the first core arm 21a and the third core arm 21c, and a second circular arc chamfer 23b is formed between the second core arm 21b and the third core arm 21 c.

Through the arrangement, the whole magnetic core 2 is of a U-shaped structure with arc chamfers, so that the utilization rate of the magnetic core 2 can be improved, magnetic leakage is reduced, and heat dissipation and installation are facilitated. The circular arc chamfer makes it smoother and more round. By the aid of the winding machine, scratches or breakage can be avoided during winding, and the integrity and reliability of the coil are protected. Meanwhile, the arc chamfer can reduce stress concentration on the surface of the magnetic core 2 and improve the mechanical strength and stability of the magnetic core 2.

Specifically, the magnetic core 2 is a manganese-zinc ferrite magnetic core 2. The material has the characteristics of wide temperature range and low loss, and the power consumption per unit volume is relatively low within the range of 25-120 ℃. Besides the characteristics of wide temperature and low loss, the material has high temperature stability of magnetic permeability, and the magnetic permeability is higher than 2000 at the low temperature of-40 ℃, so that the material is very suitable for being used outdoors and in cold places. In addition, the material also has the characteristic of high saturation magnetic induction intensity, and can be used for working occasions with direct current bias magnetic fields, so that the material has higher use value.

Specifically, the first gap 31a and the second gap 31b are equal.

Specifically, the third gap 31c is larger than the first gap 31a and the second gap 31b.

Specifically, the first gap 31a and/or the second gap 31b is 0.55±0.05mm.

Specifically, the third gap 31c is 4.5±0.1mm.

In this embodiment, the height of the magnetic core 2 is 9.6±0.15mm, and the thickness of the magnetic core 2 (i.e., the thicknesses of the first magnetic core arm 21a, the second magnetic core arm 21b, and the third magnetic arm) is 6.2±0.15mm.

After the parameters are adopted, the magnetic field collected by the magnetic core 2 can be efficiently transmitted to the Hall chip 3, and finally, voltage signals which are in linear relation with input current are output, so that the high precision and the high linearity of the product are ensured.

In this embodiment, the above-mentioned determination of the respective parameter ranges adopts a modeling placement manner. As shown in fig. 3, a model is built (such as Maxwell magnetic field simulation software) to perform magnetic field simulation, so as to determine the optimal size and shape of the magnetic core 2, and meanwhile simulate the magnetic field intensity and stability of different spatial positions of the magnetic core 2, and determine the position where the magnetic field detection unit of the linear hall chip 3 should be placed, and the hall chip 3 should be placed in a region with higher magnetic field intensity and more uniform distribution, so as to improve the detection precision and sensitivity; the hall chip 3 should be kept at a distance from the magnetic core 2 from direct contact or from mechanical stress. In the 3D magnetic field simulation model in fig. 3, a large cube represents an air layer, a long cylinder represents a current wire to be detected, and magnetic field intensity and distribution conditions at different positions are obtained through simulation analysis.

The coordinate axis is used as a reference, the magnetic field distribution of the xy section is shown in fig. 4-6, and the preferred placement position range of the hall chip 3 is determined according to the simulation result on the graph.

Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same, and although the present utility model has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications and equivalents may be made to the technical solution of the present utility model without departing from the spirit and scope of the technical solution of the present utility model, and all such modifications and equivalents are intended to be encompassed in the scope of the claims of the present utility model.

Claims (10)

1. The Hall type high-precision open-loop current sensor is characterized by comprising a shell (1), wherein the shell (1) is internally provided with:

the magnetic core (2), the magnetic core (2) comprises a first magnetic core arm (21 a), a second magnetic core arm (21 b) and a third magnetic core arm (21 c) connected with the first magnetic core arm (21 a) and the second magnetic core arm (21 b) respectively, and a containing space (22) suitable for penetrating a current wire to be detected is formed among the first magnetic core arm (21 a), the second magnetic core arm (21 b) and the third magnetic core arm (21 c);

the Hall chip (3) is arranged in the accommodating space (22), a first gap (31 a) is reserved between the Hall chip (3) and the first magnetic core arm (21 a), a second gap (31 b) is reserved between the Hall chip (3) and the second magnetic core arm (21 b), and a third gap (31 c) is reserved between the Hall chip (3) and the third magnetic core arm (21 c).

2. The hall-type high-precision open-loop current sensor according to claim 1, wherein the first magnetic core arm (21 a) and the second magnetic core arm (21 b) are arranged in parallel, and the third magnetic core arm (21 c) is arranged perpendicular to the first magnetic core arm (21 a) and the second magnetic core arm (21 b), respectively.

3. A hall-type high-precision open-loop current sensor according to claim 1, characterized in that a first circular arc chamfer (23 a) is formed between the first magnetic core arm (21 a) and the third magnetic core arm (21 c), and a second circular arc chamfer (23 b) is formed between the second magnetic core arm (21 b) and the third magnetic core arm (21 c).

4. A hall-type high precision open loop current sensor according to claim 1, characterized in that the magnetic core (2) is a manganese zinc ferrite core (2).

5. A hall-type high accuracy open loop current sensor according to claim 1, characterized in that the first gap (31 a) and the second gap (31 b) are equal.

6. A hall-type high accuracy open loop current sensor according to claim 1, characterized in that the third gap (31 c) is larger than the first gap (31 a) and the second gap (31 b).

7. A hall high precision open loop current sensor according to claim 1, characterized in that the first gap (31 a) and/or the second gap (31 b) is 0.55 ± 0.05mm.

8. A hall high precision open loop current sensor according to claim 1, characterized in that the third gap (31 c) is 4.5±0.1mm.

9. A hall-type high precision open loop current sensor according to claim 1, characterized in that the height of the magnetic core (2) is 9.6±0.15mm.

10. A hall-type high precision open loop current sensor according to claim 1, characterized in that the thickness of the magnetic core (2) is 6.2±0.15mm.