A racetrack-shaped magnetic ring for a dual-range current sensor

Abstract

The present invention discloses a runway-shaped magnetic ring for a dual-range current sensor, belonging to the technical field of current sensors. The present invention has a symmetrical double "U" structure. Each side of the "U" structure includes a curved magnetic-concentrating semi-ring and two straight magnetic strips arranged at both ends of the curved magnetic-concentrating semi-ring. Air gaps are provided in the middle of the two relatively arranged straight magnetic strips, and a first magnetic-sensitive element is arranged at any one of the air gaps; a second magnetic-sensitive element is arranged in the magnetic shunt area between the center of the magnetic ring and the magnetic ring. And it is applied to a current sensor. The magnetic aggregation effect in the air gap is enhanced. By arranging the first magnetic-sensitive element here, the sensitivity and resolution of small current detection can be improved; the magnetic shunt effect between the center of the magnetic ring and the magnetic ring is better. By arranging the second magnetic-sensitive element in the magnetic shunt area, the detection range of the current sensor can be broadened. Moreover, it has higher sensitivity, better linearity, smaller volume, and better measurement stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of current sensors, and particularly relates to a dual-range runway-shaped magnetic ring for a current sensor. Background Art

[0002] Currently, the mainstream current sensors based on the magnetic effect of current mainly include Hall current sensors, giant magnetoresistive current sensors, and tunnel magnetoresistive current sensors, etc. Such sensors use magnetic sensitive elements to measure the magnetic field generated by the measured current. The working principle is as follows: Based on the theory that a magnetic focusing ring can magnetically focus the magnetic field generated by the measured current and the principle of magnetic flux continuity, an air gap is formed by opening the magnetic ring to gather the magnetic field, and then the magnetic sensitive element is placed in the air gap of the magnetic focusing ring to convert the measured magnetic signal into an electrical signal, thereby obtaining the magnitude of the measured current.

[0003] The magnetic ring plays a very important role in current sensor technology. It can be used as a magnetic focusing device to focus the magnetic field generated by the current at the air gap, increasing the magnetic induction intensity component detected by the magnetic sensitive element and improving the measurement accuracy of the magnetic field. It can also be used as a magnetic shunt device to shunt and weaken the magnetic field between the center of the magnetic ring and the magnetic ring. By finding a suitable position to place the magnetic sensitive element in this area, a large current can be shunted and measured by the magnetic sensitive element.

[0004] The single-air-gap C-shaped structure magnetic ring and the double-air-gap circular structure magnetic ring are the commonly used magnetic ring structures in traditional current sensors. For example, the magnetic ring used in the patented technology with the authorization announcement number CN209728029U is a traditional C-shaped structure. Its specific form is: a single-air-gap C-shaped structure is formed by opening an annular magnetic ring, and the magnetic field is focused at the air gap using the magnetic focusing effect, making the magnetic field at this point much larger than the magnetic field without a magnetic ring, thereby improving the resolution of small current measurement. However, the overly strong magnetic field generated by a large current easily causes the magnetic sensitive element to enter the magnetic saturation state, so it is not suitable for large-range current measurement. The magnetic focusing of the magnetic ring has a magnetic shunt effect on the magnetic field near the magnetic ring. Therefore, magnetic shunt technology can be used to shunt the magnetic field between the center of the magnetic ring and the magnetic ring to form a weaker magnetic field signal, greatly increasing the measurement range of the measured current. For example, the patented technology with the authorization announcement number CN110146737A shunts the magnetic field near the air gap based on the magnetic shunt principle to achieve an expansion of the current measurement range. However, the disadvantages are complex structure, poor flexibility in choosing the measurement position, single measurement range, and insufficient measurement accuracy for small-range currents; while the runway-shaped magnetic ring of the present invention selects a measurement point at a place with a larger space on the basis of using magnetic shunt technology, with a more stable structure. At the same time, it can measure small-range currents at the air gap, achieving a more optimized and simple structure, with better smoothness and linearity.

[0005] In view of the situation that the current measurement range is uncertain in different environments, most of the current sensors in use are single-range current sensors. To achieve dual-range current measurement, the widely used methods at present are as follows: First, use multiple current sensors, but this brings an increase in cost and the volume of the entire system, reducing the convenience brought by the current sensor itself; Second, add multiple magnetic rings in a current sensor, but the complexity of the structure not only brings difficulties in operation and production, but also the mutual interference between the magnetic rings will affect the accuracy of current measurement. For example, the two patent technologies with the authorization announcement numbers CN212872620U and CN109142837B both use two magnetic rings to form a current sensor to obtain a larger current measurement range or achieve dual-range current measurement, but both patent technologies show the complexity of the structure, affecting indicators such as the accuracy and linearity in the measurement results of the sensor while increasing the cost. And the present invention successfully realizes the current measurement of a large range and a small range on the premise of only using one magnetic ring, with extremely strong environmental applicability.

[0006] On the premise of avoiding increasing the number of sensors and magnetic rings, based on the magnetic shunt principle of a magnetic ring with an air gap, the currently used method is to place sensing chips at the magnetic shunt and magnetic aggregation points of a magnetic ring respectively, so as to carry out the dual-range measurement of current. For example, the special technology with the authorization announcement number CN114778920A uses a double-air-gap circular magnetic ring structure to achieve dual-range current measurement. However, from the measurement results, the circular magnetic ring structure has certain limitations in aspects such as magnetic shunt effect and magnetic field linearity. In view of the deficiencies reflected in the above technical solutions, the present invention proposes a racetrack-shaped magnetic ring structure for a current sensor, which has higher linearity and better magnetic shunt effect. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art solutions, the present invention provides a dual-range racetrack-shaped magnetic ring for a current sensor.

[0008] The dual-range racetrack-shaped magnetic ring described in the present invention is a symmetric double "U" type structure. Each side of the "U" type structure includes a curved magnetic-concentrating semi-circular ring and two straight magnetic strips arranged at both ends of the curved magnetic-concentrating semi-circular ring. Air gaps are provided in the middle of the two relatively arranged straight magnetic strips, and a first magnetic-sensitive element is arranged at any air gap for the current sensor to detect small-range current; a second magnetic-sensitive element is arranged in the magnetic shunt area from the center of the magnetic ring to the magnetic ring for the current sensor to detect large-range current.

[0009] Furthermore, the straight magnetic strip and the curved magnetic-concentrating semi-circular ring can be integrally formed or a split structure. In the split structure, the straight magnetic strip and the curved magnetic-concentrating semi-circular ring are assembled together into a racetrack-shaped groove with a suitable size and fixed for fitting use.

[0010] Further, the sum of the lengths of the two straight magnetic strips and the air gap width is greater than the outer diameter of the magnetic focusing semi-circular ring.

[0011] Further, the dual-range racetrack-shaped magnetic ring is made of soft magnetic materials such as silicon steel, permalloy, or iron-based amorphous.

[0012] Further, the racetrack-shaped magnetic ring is made of soft magnetic thin strip materials through a laminated structure, which can effectively reduce magnetic eddy current loss, make heat dissipate more easily, and have better stability.

[0013] When the above dual-range racetrack-shaped magnetic ring is applied to a current sensor, when measuring a small-range current, the racetrack-shaped magnetic ring shows a better magnetic focusing effect on the magnetic field signal generated in the air gap at the midpoint of the two straight magnetic strip parts of the magnetic ring for the measured current, with higher resolution and sensitivity; moreover, when measuring the same magnitude of current, the measurement result of the racetrack-shaped magnetic ring has better linearity and accuracy. When measuring a large-range current, the racetrack-shaped magnetic ring has a stronger magnetic shunt effect on the magnetic field signal between the center of the magnetic ring and the magnetic ring, thereby expanding the current detection range of the large range, and at the same time having better linearity and a smaller volume.

[0014] Compared with the traditional single-air-gap C-shaped magnetic ring and the traditional double-air-gap magnetic ring, the racetrack-shaped magnetic ring of the present invention breaks through the symmetrical magnetic circuit structure of the traditional C-shaped magnetic ring by designing a racetrack-shaped magnetic ring composed of a combination of a straight magnetic strip structure and a curved magnetic focusing semi-circular ring structure, changes the magnetic field distribution between the air gap of the magnetic ring, the magnetic ring, and the center of the magnetic ring, can obtain a larger magnetic shunt ratio and a more uniform magnetic field distribution interval, makes the magnetic shunt effect reach the best, expands the current detection range and obtains more stable magnetic field measurement performance, and gives full play to the advantages of the magnetic shunt technology. A magnetic ring air gap is provided at the center of each of the two straight magnetic strips of the racetrack-shaped magnetic ring, and a first magnetic sensitive element is provided at the center of the air gap; when measuring a small-range current, the racetrack-shaped magnetic ring shows a better magnetic focusing effect on the magnetic field signal generated in the air gap at the midpoint of the two straight magnetic strip parts of the magnetic ring for the measured current, with higher resolution and sensitivity; moreover, when measuring the same magnitude of current, the measurement result of the racetrack-shaped magnetic ring has better linearity and accuracy. A second magnetic sensitive element is provided at a suitable position with a large magnetic shunt and uniform magnetic field distribution between the racetrack-shaped magnetic ring and the center of the magnetic ring. When measuring a large-range current, the racetrack-shaped magnetic ring has a stronger magnetic shunt effect on the magnetic field signal between the center of the magnetic ring and the magnetic ring, thereby expanding the current detection range of the large range, and at the same time having better linearity and a smaller volume.

[0015] The present invention adopts a combination of a straight magnetic strip and a curved magnetic-concentrating semi-circular ring. By changing the magnetic field distribution within the magnetic ring, on the one hand, the magnetic induction intensity within the air gap of the magnetic ring can be enhanced (the magnetic-concentration effect is enhanced), and at the same time, the magnetic induction intensity from the center of the magnetic ring to the magnetic ring can be further weakened or shunted (the magnetic-shunting effect is better). When applied in a current sensor, it has the characteristics and advantages of small volume, strong practicability, low cost, and multiple beneficial effects such as magnetic concentration and magnetic shunting in a single magnetic-ring structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the racetrack-shaped magnetic-ring structure of the present invention;

[0017] Figure 2 Schematic diagram of the simulation model for testing the magnetic-concentration and magnetic-shunting positions without a magnetic ring;

[0018] Figure 3 Schematic diagram of the double-air-gap circular magnetic-ring structure;

[0019] Figure 4 Schematic diagram for testing the magnetic stability near the large-range measurement points of the racetrack-shaped magnetic ring in the embodiment;

[0020] Figure 5 Schematic diagram for testing the magnetic stability near the large-range measurement points of the double-air-gap circular magnetic ring in the embodiment;

[0021] Figure 6 Schematic diagram of the rectangular-structure magnetic-ring structure;

[0022] Figure 7 Schematic diagram of the application principle of the racetrack-shaped magnetic ring of the present invention in a current sensor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0024] A dual-range racetrack-shaped magnetic ring for a current sensor, as Figure 1 shown, is a symmetric double-"U" type structure; for the convenience of description, in the figure, the magnetic ring on each side is divided into a straight track and a curved track with a dashed line, and the straight-track part is called the straight magnetic strip (2, 5, 9, 11), and the curved-track part (1, 8) is called the curved magnetic-concentrating semi-circular ring.

[0025] At both ends of the curved magnetic-concentrating semi-circular rings (1, 8) on each side, they are respectively connected to the short sides of a magnetic-ring straight magnetic strip, forming a "U"-shaped structure. Two symmetrical double "U"-shaped structures are arranged oppositely, and an air gap is arranged in the middle of the two oppositely arranged straight magnetic strips; that is, a first air gap 3 is arranged between the first straight magnetic strip 2 and the second straight magnetic strip 5, and symmetrically, a second air gap 10 is arranged between the third straight magnetic strip 11 and the fourth straight magnetic strip 9.

[0026] Embodiment 1

[0027] In this embodiment, by arranging an exciting current wire 6 at the center of the racetrack-shaped magnetic ring as shown in Figure 1 , arranging a first magnetic-sensitive element 4 at the air gap 3 (or air gap 10), and arranging a second magnetic-sensitive element 7 in the magnetic shunt area between the magnetic-ring center and the magnetic ring, the performance of the above double-range racetrack-shaped magnetic ring is tested.

[0028] As shown in Figure 2 , when there is no magnetic ring, through Maxwell simulation test: when a current of 10 A is passed through the central exciting current wire 6, at the first magnetic-sensitive element 4 in the air gap (the original small-range magnetic-concentrating place), the measured magnetic induction intensity is about 88.4 T; when a current of 1000 A is passed through the central exciting current wire 6, at the second magnetic-sensitive element 7 which is 30 mm away from the magnetic-ring center in the X-axis direction (the original large-range magnetic shunt place), the measured magnetic induction intensity is about 6.01 mT.

[0029] Set the Figure 1 air gap width (X-axis direction) of the double-range racetrack-shaped magnetic ring shown as 6 mm, air gap length (Y-axis direction) as 10 mm, magnetic-ring height as 20 mm, magnetic-ring thickness as 10 mm, inner ring radius of the curved magnetic-concentrating semi-circular ring as 20 mm, outer ring radius as 30 mm, width of the magnetic-ring straight magnetic strip as 10 mm, and length of the magnetic-ring straight magnetic strip as 30 mm. Through Maxwell simulation test: when a current of 10 A is passed through the central exciting current wire 6, at the first magnetic-sensitive element 4 (small-range magnetic-concentrating place), the measured magnetic induction intensity is about 1046.4584 𝜇T; when a current of 1000 A is passed through the central exciting current wire 6, at the second magnetic-sensitive element 7 which is 30 mm away from the magnetic-ring center in the X-axis direction (large-range magnetic shunt place), the measured magnetic induction intensity is about 780.6451 T.

[0030] Maintaining the current flowing through the excitation current conductor of the dual-range racetrack-shaped magnetic ring in this embodiment at 1000A, the position of the large-range detection point on the X-axis was varied. When the large-range detection point was 20mm from the current center, the magnetic induction intensity at the second magnetic sensitive element was 3185.9439𝜇T. When the large-range detection point was 40mm from the center of the racetrack-shaped magnetic ring, the magnetic induction intensity at the second magnetic sensitive element was 161.7388𝜇T. On the line segment between these two endpoints, the magnetic induction intensity at the second magnetic sensitive element decreases as it approaches the inner wall of the curve.

[0031] According to the above simulation test results, compared with the case without a magnetic ring, the dual-range runway-shaped magnetic ring in this embodiment can increase the magnetic induction intensity by nearly 12 times through magnetic concentration, and can also attenuate the magnetic induction intensity by nearly 7.7 times through magnetic shunting; and when the detection point is closer to the inner wall of the magnetic ring, the attenuation multiple can reach 100 times. It can be seen that the use of the magnetic ring described in the present invention has obvious magnetic concentration and shunting effects.

[0032] For example Figure 3 The double air gap circular magnetic ring shown in the figure is tested for performance. The air gap width (X axis) of the circular magnetic ring is set to 6mm, the air gap length (Y axis) is set to 10mm, the magnetic ring height is set to 20mm, the inner ring radius of the magnetic ring is set to 50mm, and the outer ring radius is set to 60mm. The thickness of the circular magnetic ring is Figure 1 The runway-shaped magnetic ring is the same (10mm), and the outer radius is the same as half of the longest side of the runway-shaped magnetic ring (the length of the straight magnetic strip plus the outer radius of the semicircle); an excitation current conductor 6 is set at the center of the magnetic ring, and the magnetic ring air gaps 12 and 14 are set between the two symmetrical sides of the magnetic ring 13 for the current sensor to measure the small range; the large-range measurement point should be located in the magnetic shunt area between the center of the magnetic ring and the magnetic ring. In this test, it is set in the X direction, and at the same time, the distance between the large-range measurement point and the excitation current conductor of the double-gap circular magnetic ring and the runway-shaped magnetic ring is ensured to be the same. That is, both are 30 mm; a second magnetic sensitive element 7 is placed at the large-scale measurement point. When a current of 1000 A flows through the excitation current wire 6, the magnetic field measured by the second magnetic sensitive element is 3.3 mT, which is approximately 4.3 times that of the racetrack-shaped magnetic ring and is much larger than the magnetic field at this point when the racetrack-shaped magnetic ring is used. Therefore, under the same conditions, when measuring currents of the same magnitude, the racetrack-shaped magnetic ring and the traditional double-air-gap circular magnetic ring have better magnetic shunting effects, and the volume of the racetrack-shaped magnetic ring shown in the present invention is much smaller than that of the traditional double-air-gap circular magnetic ring.

[0033] The current flowing through the excitation current wire of the dual-range racetrack-shaped magnetic ring in this embodiment is kept at 1000A. When the large-range detection point is located 30mm away from the center of the racetrack-shaped magnetic ring, the magnetic induction intensity measured at the second magnetic sensitive element 7 is 780.6451𝜇T. Figure 4As shown in the figure, taking this point as the reference point, an appropriate number of test points are selected on the virtual line segment 19 in the X-axis direction near the reference point: a test point is set at 0.1 mm in the positive X-axis direction from the reference point, and the measured magnetic induction intensity is 770.7383 μT; a test point is set at 0.2 mm in the positive X-axis direction from the reference point, and the measured magnetic induction intensity is 760.8316 μT; a test point is set at 0.1 mm in the negative X-axis direction from the reference point, and the measured magnetic induction intensity is 790.5518 μT; a test point is set at 0.2 mm in the negative X-axis direction from the reference point, and the measured magnetic induction intensity is 800.4583 μT. An appropriate number of test points are selected on the virtual line segment 18 in the Y-axis direction near the reference point: a test point is set at 0.1 mm in the positive Y-axis direction from the reference point, and the measured magnetic induction intensity is 778.4572 μT; a test point is set at 0.2 mm in the positive Y-axis direction from the reference point, and the measured magnetic induction intensity is 776.2694 μT; a test point is set at 0.1 mm in the negative Y-axis direction from the reference point, and the measured magnetic induction intensity is 782.8329 μT; a test point is set at 0.2 mm in the negative Y-axis direction from the reference point, and the measured magnetic induction intensity is 785.0207 μT. Based on the above data, the variance reflecting the magnetic field stability in the Y-axis direction is calculated to be 9.5732, and the variance reflecting the magnetic field stability in the X-axis direction is 197.

[0034] As Figure 5 shown, the inner radius of the double-gap circular magnetic ring is set to 20 mm and the outer radius is set to 30 mm, that is, the outer radius length is the same as the outer radius of the magnetic flux concentrating semi-circular ring of the racetrack-shaped magnetic ring. At this time, the spatial size of the magnetic flux shunting area of the racetrack-shaped magnetic ring and the circular double-gap magnetic ring is similar in the Y-axis direction. When a current of 1000 A is passed through the exciting current wire, at the second magnetic sensor 7 (large-range detection point) located 18.7 mm away from the center of the circular magnetic ring (selecting a point where the magnetic induction intensity is close to 780.6451 μT of the racetrack-shaped magnetic ring under the same current condition), the measured magnetic induction intensity is 805.5070 T, using this point as the reference point, select appropriate test points on the Y-axis dashed line segment 21 near the reference point: a test point is set 0.1 mm from the reference point in the positive Y direction, and the measured magnetic induction intensity is 805.0151𝜇T; a test point is set 0.2 mm from the reference point in the positive Y direction, and the measured magnetic induction intensity is 796.9653𝜇T; a test point is set 0.1 mm from the reference point in the negative Y direction, and the measured magnetic induction intensity is 797.533𝜇T; a test point is set 0.2 mm from the reference point in the negative Y direction, and the measured magnetic induction intensity is 789.5590𝜇T. The variance of the Y-axis magnetic field stability is calculated to be 34.6702. The inner ring radius of the double-gap circular magnetic ring is set to 50mm and the outer ring radius is set to 60mm, that is, the length of the outer radius is the same as the longest side of the runway shape (the length of the straight magnetic strip plus the outer radius of the semicircle). At this time, the space size of the magnetic shunt area of the runway-shaped magnetic ring and the circular double-gap magnetic ring in the X-axis direction is similar. When a current of 1000A is passed through the excitation current wire, the magnetic induction intensity is measured to be 774.6493μT at the second magnetic sensitive element 7 (large-range detection point) located 43mm from the center of the circular magnetic ring (a point where the magnetic induction intensity is close to the magnetic induction intensity of the runway-shaped magnetic ring 780.6451𝜇T under the same current). Taking this point as the reference point, appropriate test points are selected near the reference point and on the X-axis dotted line segment 20: A test point was set 0.1 mm from the test point in the positive X direction, and the measured magnetic induction intensity was 761.1633 𝜇T. A test point was set 0.2 mm from the reference point in the positive X direction, and the measured magnetic induction intensity was 747.6773 𝜇T. A test point was set 0.1 mm from the reference point in the negative X direction, and the measured magnetic induction intensity was 788.1353 𝜇T. A test point was set 0.2 mm from the reference point in the negative X direction, and the measured magnetic induction intensity was 801.6213 𝜇T. The calculated variance of the X-axis, reflecting the smoothness of the magnetic field, was 363.744.

[0035] Comparing the circular double-air-gap magnetic ring and the racetrack-shaped magnetic ring of the present invention, the magnetic induction intensity variance of the magnetic ring of the present invention at the sampling point near the detection point is smaller, indicating that the magnetic field is more stable, which makes the magnetic ring have better stability and environmental adaptability when used in current sensors.

[0036] It should be noted that, for ease of description, the lengths of the inner and outer diameters of the circular double-air-gap magnetic ring in the embodiments do not include the air gap width.

[0037] Example 2

[0038] In this embodiment, set Figure 1The air gap length (Y-axis direction) of the shown double-range racetrack-shaped magnetic ring is 10 mm, the air gap width (X-axis direction) is 6 mm, the magnetic ring height is 20 mm, the magnetic ring thickness is 10 mm, the inner radius of the curved magnetic-concentrating semi-circular ring is 20 mm, the outer radius is 30 mm, the width of the straight magnetic strip of the magnetic ring is 10 mm, and the length of the straight magnetic strip of the magnetic ring is 30 mm; when a current of 600 A to 1200 A (step size is 10 A) is passed through the central excitation current wire 6, at the second magnetic sensitive element 7 which is 30 mm in the X-axis direction from the center of the measured current (at the large-range magnetic shunt), the measured magnetic induction intensity linearity is about 0.013795%.

[0039] Set Figure 3 The air gap length (Y-axis direction) of the shown circular double-air-gap magnetic ring is 10 mm, the air gap width (X-axis direction) is 6 mm, the magnetic ring height is 20 mm, the magnetic ring thickness is 10 mm, the outer radius is 60 mm, and the inner radius is 50 mm; when a current of 600 A to 1200 A (step size is 10 A) is passed through the central excitation current wire 6, at the second magnetic sensitive element 7 which is 43 mm in the X-axis direction from the center of the measured current (selecting a point where the magnetic induction intensity is close to 780.6451 μT of the racetrack-shaped magnetic ring under the same current condition) (at the large-range magnetic shunt), the measured magnetic induction intensity linearity is about 0.024695%;

[0040] Set as Figure 6 The outer length of the shown rectangular magnetic ring is 80 mm, the outer width is 60 mm, the inner length is 60 mm, the inner width is 40 mm, the magnetic ring height is 20 mm, and the magnetic ring thickness is 10 mm; the length of the long arm of the rectangle is the same as the length of the straight magnetic strip of the racetrack-shaped magnetic ring. Magnetic ring air gaps 15 and 17 are set at the center of the long arm, the air gap length (Y-axis direction) is 10 mm, and the air gap width (X-axis direction) is 6 mm; an excitation current wire 6 is set at the central symmetry point of the rectangular magnetic ring. In this embodiment, its large-range measurement point is located in the shunt area of the connection line between the center of the short arm 16 of the magnetic ring and the center of the excitation current wire 6, and the distance from the excitation current wire is 27.5 mm (selecting a point where the magnetic induction intensity is close to 780.6451 μT of the racetrack-shaped magnetic ring under the same current condition). A second magnetic sensitive element 7 is placed at the large-range measurement point. When a current of 600 A to 1200 A (step size is 10 A) is passed through the central excitation current wire 6, the measured magnetic induction intensity linearity at the second magnetic sensitive element 7 is about 0.046431%.

[0041] Comparing the linearities of the measurement results of the racetrack-shaped magnetic ring, the circular double-air-gap magnetic ring, and the rectangular magnetic ring, the racetrack-shaped magnetic ring described in the present invention has a great advantage in linearity.

[0042] It should be noted that for the convenience of description, the lengths of the inner and outer diameters of the circular double-air-gap magnetic ring involved in the embodiments do not include the air-gap width; the outer length and inner length of the rectangular magnetic ring also do not include the air-gap width.

[0043] Embodiment 3

[0044] In this embodiment, the dimensions of the double-range racetrack-shaped magnetic ring are basically the same as those in Embodiment 1. The differences are as follows: the air-gap width is different; the exciting current wire 6 is located at the center of the racetrack-shaped magnetic ring, and the set current magnitude is 10 A. The air-gap width is changed: when the air-gap width is 2 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 3138.0269 μT; when the air-gap width is 4 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 1569.5371 μT; when the air-gap width is 6 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 1046.4584 μT; when the air-gap width is 8 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 780.0508 μT.

[0045] It can be concluded that the smaller the air-gap width on the racetrack-shaped magnetic ring, the better the magnetic flux concentration effect. In the specific implementation process, factors such as the magnetic field saturation intensity of the selected magnetic sensitive chip and the thickness of the magnetic field probe inserted into the air-gap should be comprehensively considered, and the air-gap width should be selected by making a compromise. Generally, the selected width is between 2 mm and 15 mm.

[0046] Embodiment 4

[0047] In this embodiment, the dimensions of the double-range racetrack-shaped magnetic ring are basically the same as those in Embodiment 1. The differences are as follows: the magnetic ring dimensions are different; when the exciting current wire passes a current of 10 A, when the magnetic ring dimensions are an inner ring radius of 20 mm and an outer ring radius of 30 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 1046.4584 μT; when the magnetic ring dimensions are an inner ring radius of 30 mm and an outer ring radius of 40 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element is 1044.6991 μT; when the magnetic ring dimensions are an inner ring radius of 40 mm and an outer ring radius of 50 mm, the magnetic induction intensity magnitude at the first magnetic sensitive element 4 is 1045.9764 μT.

[0048] When the current passing through the excitation current wire is 1000 A, when the size of the magnetic ring is such that the inner ring radius is 20 mm, the outer ring radius is 30 mm, and the length of the straight magnetic strip is 30 mm, the magnetic induction intensity at the second magnetic sensitive element 30 mm away from the center of the wire (selecting the center of the curved magnetic focusing semi-circular ring as the measurement point) is 780.6451 μT; when the size of the magnetic ring is such that the inner ring radius is 3 mm, the outer ring radius is 40 mm, and the length of the straight magnetic strip is 40 mm, the magnetic induction intensity at the second magnetic sensitive element 40 mm away from the center of the wire (selecting the center of the curved magnetic focusing semi-circular ring as the measurement point) is 795.9005 μT; when the size of the magnetic ring is such that the inner ring radius is 40 mm, the outer ring radius is 50 mm, and the length of the straight magnetic strip is 50 mm, the magnetic induction intensity at the second magnetic sensitive element 7 at 50 mm away from the center of the wire (selecting the center of the curved magnetic focusing semi-circular ring as the measurement point) is 716.6806 μT.

[0049] It can be seen from this embodiment that: the appropriate magnetic ring size and the appropriate current detection point (the placement point of the magnetic sensitive element) can be selected according to the working range of the magnetic sensitive element and the magnitude range of the excitation current; in this embodiment, through comprehensive consideration, the inner ring radius of the magnetic ring can be from 5 mm to 50 mm, the outer ring radius of the magnetic ring can be from 15 mm to 100 mm, the small-range detection point is located at the center of the air gap, and the large-range detection point is located at the center of the curved magnetic focusing semi-circular ring.

[0050] Application Example 1

[0051] Fix and assemble the racetrack-shaped magnetic ring into the insulating mold, such as Figure 7As shown in the figure, two PCB probe boards 22 and 23 integrated with TMR sensing chips and in-situ feedback coils are inserted into the established positions (small-range measurement points and large-range measurement points), and the PCB probe boards are connected to the signal processing circuit board with FPC flexible cables. A measured current is passed through the signal wire to be measured, and its direction is perpendicular to the plane and inward, generating a vortex magnetic field in space. Most of the magnetic field is concentrated by the magnetic ring at the air gap of the magnetic ring, forming a larger magnetic field, and at the same time, a smaller magnetic field is formed at the magnetic shunt. The magnetic sensitive axes of the magnetic sensitive elements on the two probe boards are respectively the same as the main component direction of the magnetic induction intensity of the measured magnetic field at the measurement points. The magnetic sensitive elements detect the magnetic field signal and output the voltage in differential form, which is sent to the instrumentation amplifier 24 or 25 through switching devices such as relays; the instrumentation amplifier amplifies the weak differential voltage signal, and the power amplifier 26 linearly converts the voltage signal into a feedback current signal to drive the feedback coil; the feedback coil generates a reverse magnetic field to balance the magnetic field generated by the measured current, and the system finally reaches equilibrium, and the magnetic induction intensity at the detection point stabilizes at a small value. The current signal on the feedback coil is serially sampled with a power resistor 27 to convert the current signal into a voltage signal. This analog voltage signal is converted into a digital signal through the instrumentation amplifier 28 and ADC, and after being processed and calibrated by the MCU, the value of the measured current can be obtained through the value of this voltage signal. At the same time, it is output to the host computer at the PC end through SPI communication for display, so as to achieve the purpose of real-time display and monitoring of the amplitude and frequency of the measured current on the host computer.

[0052] The high-precision small-range current detection and high-stability large-range current detection described in this embodiment are realized under a single magnetic ring structure. The signals of both ranges can be measured independently or simultaneously. When traditional large-range current sensors measure small currents, the accuracy and linearity of the measurement results are insufficient; traditional small-range current sensors cannot measure large currents. This system automatically differentiates data of different ranges, that is, fuses data of large and small ranges, solving the problem of limitations in environmental applicability of two independent ranges, making full use of the advantages of high sensitivity and high resolution of the small range and the superior range performance of the large range.

[0053] This embodiment combines magnetic shunt and magnetic aggregation technologies, magnetic sensor technologies, adopts a closed-loop structure and in-situ feedback technology to cancel the magnetic field signal generated by the primary current to achieve a magnetic balance state, further improving the system work range, sensitivity, etc. And only a racetrack-shaped magnetic ring structure is used to complete the current measurement of two ranges, greatly saving cost and volume.

[0054] The dual-range racetrack-shaped magnetic ring is made of soft magnetic materials such as silicon steel, permalloy or iron-based amorphous.

[0055] The magnetosensitive element is selected from an anisotropic magnetoresistive sensing chip, a Hall sensing chip, a giant magnetoresistive sensing chip or a tunneling magnetoresistive sensing chip.

[0056] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any sense, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A dual-range runway-shaped magnetic ring for a current sensor, characterized in that: It is a symmetric double "U" - shaped structure. Each "U" - shaped structure on each side includes a curved magnetic - concentrating semi - ring and two straight magnetic strips arranged at both ends of the curved magnetic - concentrating semi - ring; an air gap is arranged between two relatively - arranged straight magnetic strips, and a first magnetic - sensitive element is arranged at any air gap for the current sensor to detect small - range currents; a second magnetic - sensitive element is arranged in the magnetic - shunting area between the center of the magnetic ring and the magnetic ring for the current sensor to detect large - range currents; the sum of the lengths of the two straight magnetic strips and the width of the air gap is greater than the outer diameter of the magnetic - concentrating semi - ring; the soft magnetic thin - strip material used for the racetrack - shaped magnetic ring is made through a laminated structure; When measuring small - range currents, the racetrack - shaped magnetic ring shows a better magnetic - concentrating effect on the magnetic - field signals generated by the measured current in the air gap at the mid - ends of the two straight - magnetic - strip parts of the magnetic ring, with higher resolution and sensitivity; moreover, when measuring currents of the same magnitude, the measurement results of the racetrack - shaped magnetic ring have better linearity and accuracy; when measuring large - range currents, the racetrack - shaped magnetic ring has a stronger magnetic - shunting effect on the magnetic - field signals between the center of the magnetic ring and the magnetic ring, thereby expanding the current - detection range of the large - range current, and at the same time having better linearity and a smaller volume.

2. The dual-range runway-shaped magnetic ring for a current sensor according to claim 1, characterized in that: The straight magnetic strip and the curved magnetic - concentrating semi - ring are integrally formed.

3. The dual-range runway-shaped magnetic ring for a current sensor according to claim 1, characterized in that: The straight magnetic strip and the curved magnetic - concentrating semi - ring are of a split - type structure.

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