Runway-shaped magnetic ring for double-range current sensor

Abstract

The invention discloses a runway-shaped magnetic ring for a double-range current sensor, and belongs to the technical field of current sensors. The device is of a symmetrical double-U-shaped structure, and the U-shaped structure on each side comprises a curve magnetism gathering semicircular ring and two straight magnetic strips arranged at the two ends of the curve magnetism gathering semicircular ring. An air gap is formed between the two straight magnetic strips which are oppositely arranged, and a first magnetic sensitive element is arranged at any air gap; and a second magnetic sensitive element is arranged in a magnetic shunting area between the center of the magnetic ring and the magnetic ring. The magnetic sensor is applied to the current sensor, the magnetic aggregation effect in an air gap is enhanced, and the sensitivity and the resolution ratio of small current detection can be improved by arranging the first magnetic sensitive element; the magnetic shunting effect between the center of the magnetic ring and the magnetic ring is better, and the detection range of the current sensor can be widened by arranging the second magnetic sensitive element in the magnetic shunting area. And the sensitivity is higher, the linearity is better, the size is smaller, and the measurement stability is better.

Description

Technical Field

[0001] The invention belongs to the technical field of current sensors, and in particular relates to a dual-range racetrack-shaped magnetic ring used for current sensors. Background Art

[0002] At present, the mainstream current sensors based on the magnetic effect of current mainly include Hall current sensors, giant magnetoresistance current sensors and tunnel magnetoresistance current sensors. This type of sensor uses magnetic sensitive elements to measure the magnetic field generated by the measured current. The working principle is based on the theory that the magnetic field generated by the measured current can be magnetically concentrated by using a magnetic ring and the principle of magnetic flux continuity. The magnetic ring is opened to form an air gap to concentrate the magnetic field. The magnetic sensitive element is then placed in the air gap of the magnetic 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 gathering device to gather the magnetic field generated by the current at the air gap, increase the magnetic induction intensity component detected by the magnetic sensitive element, and improve the measurement accuracy of the magnetic field. It can also be used as a magnetic shunt device to shunt and weaken the magnetic field from the center of the magnetic ring to the magnetic ring. Find a suitable position in this area to place the magnetic sensitive element, so that a large current can be measured by the magnetic sensitive element through shunt.

[0004] Single-gap C-shaped magnetic ring and double-gap circular magnetic ring are 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-gap C-shaped structure is formed by opening an annular magnetic ring, and the magnetic field is gathered at the air gap by using the magnetic gathering effect, so that the magnetic field at this place is much larger than the magnetic field without the magnetic ring, thereby improving the resolution of small current measurement. However, the excessively strong magnetic field generated by a larger current can easily cause the magnetic sensitive element to enter a magnetic saturation state, so it is not suitable for large-scale current measurement. The magnetic concentration of the magnetic ring will have a magnetic shunting effect on the magnetic field near the magnetic ring. Therefore, the magnetic shunting technology can be used to shunt the magnetic field from the center of the magnetic ring to the magnetic ring, forming a weaker magnetic field signal, which greatly improves the range of the measured current. For example, the patent technology with the authorization announcement number CN110146737A is based on the magnetic shunting principle to shunt the magnetic field near the air gap, thereby expanding the current range. However, the disadvantages are complex structure, poor flexibility in selecting the measurement position, and a single range, and the measurement accuracy of small-range current is insufficient. The runway-shaped magnetic ring of the present invention selects measurement points in a larger space on the basis of utilizing the magnetic shunting technology, and the structure is more stable. At the same time, small-range current measurement can be performed at the air gap, achieving a more optimized simple structure with better stability and linearity.

[0005] In view of the situation that the current range is uncertain in different environments, most of the current sensors currently used are single-range current sensors. In order to achieve dual-range measurement of current, the methods currently widely used are: 1. Use multiple current sensors, but this brings about an increase in cost, an increase in the volume of the entire system, and reduces the convenience brought by the current sensor itself; 2. Add multiple magnetic rings to 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 patented technologies with authorization announcement numbers CN212872620U and CN109142837B both use two magnetic rings to form a current sensor to obtain a larger current measurement range or realize dual-range current measurement, but both patented technologies show structural complexity, which affects the accuracy, linearity and other indicators in the sensor measurement results while increasing costs. The present invention successfully realizes large-range and small-range current measurement under the premise of using only one magnetic ring, and has strong environmental applicability.

[0006] Under 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 a sensor chip at the magnetic shunt point and the magnetic gathering point of a magnetic ring, so as to measure the current in a dual range. 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, judging from the measurement results, the circular magnetic ring structure will have certain limitations in terms of magnetic shunt effect, magnetic field linearity, etc. In view of the shortcomings of the above technical solution, 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 of the present invention is a symmetrical double "U"-shaped structure, and each side of the "U"-shaped structure includes a curved magnetic semicircular ring and two straight magnetic strips arranged at both ends of the curved magnetic semicircular ring. An air gap is arranged between the two oppositely arranged straight magnetic strips, and a first magnetic sensitive element is arranged at any air gap for the current sensor to detect the small-range current; a second magnetic sensitive element is arranged in the magnetic shunt area between the center of the magnetic ring and the magnetic ring, which is used for the current sensor to detect the large-range current.

[0009] Furthermore, the straight magnetic strip and the curved magnetic semicircular ring can be integrally formed or in a split structure. In the split structure, the straight magnetic strip and the curved magnetic semicircular ring are assembled together into a racetrack-shaped groove of comparable size for fixed fit.

[0010] Furthermore, 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 semicircular ring.

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

[0012] Furthermore, the racetrack-shaped magnetic ring is made of a soft magnetic thin strip material through a laminated structure, so as to effectively reduce eddy current loss, dissipate heat more easily, and have better stability.

[0013] The dual-range racetrack-shaped magnetic ring is applied to the current sensor. When measuring a small-range current, the racetrack-shaped magnetic ring has a better magnetic focusing effect on the magnetic field signal generated by the measured current in the air gap at the middle end of the two straight magnetic strips of the magnetic ring, and has a higher resolution and sensitivity; and when measuring the same 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 shunting effect on the magnetic field signal from the center of the magnetic ring to the magnetic ring, thereby expanding the large-range current detection range, while having better linearity and smaller volume.

[0014] Compared with the traditional single-gap C-shaped magnetic ring and the traditional double-gap magnetic ring, the runway-shaped magnetic ring described in the present invention breaks through the symmetrical magnetic circuit structure of the traditional C-shaped magnetic ring by designing a runway-shaped magnetic ring composed of a straight magnetic strip structure and a curved magnetic semicircular ring structure, changes the magnetic field distribution between the magnetic ring air gap and the magnetic ring and the center of the magnetic ring, and can obtain a larger magnetic shunt ratio and a more uniform magnetic field distribution range, so that the magnetic shunt effect is optimized, the current detection range is expanded, and a more stable magnetic field measurement performance is obtained, giving full play to the advantages of magnetic shunt technology. A magnetic ring air gap is set at the center of each of the two straight magnetic strips of the runway-shaped magnetic ring, and a first magnetic sensitive element is set at the center of the air gap; when measuring a small-range current, the runway-shaped magnetic ring shows a better magnetic concentration effect on the magnetic field signal generated by the measured current in the air gap at the middle end of the two straight magnetic strips of the magnetic ring, and has a higher resolution and sensitivity; and when measuring currents of the same magnitude, the measurement results of the runway-shaped magnetic ring have better linearity and accuracy. A second magnetic sensitive element is arranged at a suitable position where the magnetic shunt between the runway-shaped magnetic ring and the center of the magnetic ring is large and the magnetic field distribution is uniform. When measuring a large range of current, the runway-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 large range of current detection, while having better linearity and smaller volume.

[0015] The present invention adopts a combination of straight magnetic strips and curved magnetic semicircular rings. By changing the magnetic field distribution in the magnetic ring, the magnetic induction intensity in the air gap of the magnetic ring can be enhanced (magnetic concentration effect is enhanced), and at the same time, the magnetic induction intensity between the center of the magnetic ring and the magnetic ring can be further weakened or shunted (magnetic shunting effect is better). When used in current sensors, it has the characteristics and advantages of small size, strong practicality, low cost, and multiple beneficial effects such as magnetic concentration and magnetic shunting in a magnetic ring structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the racetrack-shaped magnetic ring of the present invention; Figure 2 It is a schematic diagram of the simulation model for testing magnetic concentration and magnetic shunting positions when there is no magnetic ring; Figure 3 It is a schematic diagram of the double air gap circular magnetic ring structure; Figure 4 Schematic diagram of testing the magnetic stability near the large-range measurement point of the runway-shaped magnetic ring in the embodiment; Figure 5 Schematic diagram of testing the magnetic stability of a double-air-gap circular magnetic ring near a large-range measuring point in the embodiment; Figure 6 It is a schematic diagram of a rectangular magnetic ring structure; Figure 7 This is a schematic diagram of the application principle of the racetrack-shaped magnetic ring in the current sensor of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] A dual-range racetrack magnetic ring for current sensors, such as Figure 1 As shown, it is a symmetrical double "U"-shaped structure; for the convenience of explanation, the figure uses dotted lines to separate the straight and curved magnetic rings on each side, and the straight parts are called straight magnetic strips (2, 5, 9, 11), and the curved parts (1, 8) are called curved magnetic semicircular rings.

[0019] The two ends of the curved magnetic semicircular ring (1, 8) on each side are respectively connected to the short side of a straight magnetic strip of the magnetic ring to form a "U"-shaped structure. Two symmetrical double "U"-shaped structures are arranged opposite to each other, 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.

[0020] Example 1 In this embodiment, by Figure 1 An excitation current conductor 6 is arranged at the center of the racetrack-shaped magnetic ring, a first magnetic sensitive element 4 is arranged at the air gap 3 (or air gap 10), and a second magnetic sensitive element 7 is arranged in the magnetic shunt area from the center of the magnetic ring to the magnetic ring, and the performance of the above-mentioned dual-range racetrack-shaped magnetic ring is tested.

[0021] like Figure 2 As shown, when there is no magnetic ring, through Maxwell simulation test: when the central excitation current wire 6 is passed with a current of 10A, the magnetic induction intensity can be measured at the first magnetic sensitive element 4 in the air gap (the original small-range magnetic gathering point) to be about 88.4 T; when a current of 1000A flows through the central excitation current conductor 6, the magnetic induction intensity can be measured to be about 6.01mT at the second magnetic sensitive element 7 (the original large-range magnetic shunt position) 30mm away from the center of the magnetic ring in the X-axis direction.

[0022] set up Figure 1 The air gap width (X-axis direction) of the dual-range racetrack-shaped magnetic ring shown is 6mm, the air gap length (Y-axis direction) is 10mm, the magnetic ring height is 20mm, the magnetic ring thickness is 10mm, the inner ring radius of the curved magnetic semicircular ring is 20mm, the outer ring radius is 30mm, the magnetic ring straight magnetic strip width is 10mm, and the magnetic ring straight magnetic strip length is 30mm. Through Maxwell simulation test: when a current of 10A is passed through the central excitation current wire 6, the magnetic induction intensity can be measured at the first magnetic sensitive element 4 (small-range magnetic concentration point) to be approximately 1046.4584𝜇T; when a current of 1000A is passed through the central excitation current wire 6, the magnetic induction intensity can be measured at the second magnetic sensitive element 7 30mm away from the center of the magnetic ring in the X-axis direction (large-range magnetic shunt point) to be approximately 780.6451 T.

[0023] Keep the current in the excitation current wire of the dual-range racetrack-shaped magnetic ring in this embodiment at 1000A, and change the position of the large-range detection point on the X-axis. When the large-range detection point measurement point is 20mm away from the current center, the magnetic induction intensity at the second magnetic sensitive element is 3185.9439𝜇T; when the large-range detection point is located 40mm away from the center of the racetrack-shaped magnetic ring, the magnetic induction intensity at the second magnetic sensitive element is 161.7388𝜇T. On the line segment with these two points as endpoints, the closer to the inner wall of the curve, the smaller the magnetic induction intensity at the second magnetic sensitive element.

[0024] 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 a hundred times. It can be seen that the use of the magnetic ring described in the present invention has obvious magnetic concentration and shunting effects.

[0025] For example Figure 3 The double air gap circular magnetic ring shown in the figure is used for performance testing. The air gap width (X-axis direction) of the circular magnetic ring is set to 6mm, the air gap length (Y-axis direction) 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 racetrack-shaped magnetic ring is the same (10mm), and the outer radius length is the same as half of the longest side of the racetrack-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 symmetrical sides of the magnetic ring 13, which are used for small-range measurement of the current sensor; the large-range measurement point should be located in the magnetic shunt area from the center of the magnetic ring to the magnetic ring. This test sets it in the X direction, and at the same time ensures that the large-range measurement points of the double-air-gap circular magnetic ring and the racetrack-shaped magnetic ring are at the same distance from the excitation current conductor. That is, they are all 30mm; a second magnetic sensitive element 7 is placed at a large-range measuring point, and when a current of 1000A is passed through the excitation current wire 6, the magnetic field measured by the second magnetic sensitive element is 3.3mT, which is about 4.3 times that of the runway-shaped magnetic ring, and is much larger than the magnetic field at this point when the runway-shaped magnetic ring is used. Therefore, under the same conditions, when the runway-shaped magnetic ring and the traditional double-air-gap circular magnetic ring are measuring currents of the same magnitude, the present invention has a better magnetic shunting effect, and the volume of the runway-shaped magnetic ring shown in the present invention is much smaller than that of the traditional double-air-gap circular magnetic ring.

[0026] Keeping the current flowing through the excitation current wire of the dual-range racetrack-shaped magnetic ring in this embodiment 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, taking this point as the reference point, appropriate test points are selected near the reference point and on the X-axis dotted line segment 19: a test point is set at 0.1mm along the positive direction of the reference point, and the magnetic induction intensity is measured to be 770.7383𝜇T; a test point is set at 0.2mm along the positive direction of the reference point, and the magnetic induction intensity is measured to be 760.8316𝜇T; a test point is set at 0.1mm along the negative direction of the reference point, and the magnetic induction intensity is measured to be 790.5518𝜇T; a test point is set at 0.2mm along the negative direction of the reference point, and the magnetic induction intensity is measured to be 800.4583𝜇T. Select appropriate test points near the reference point and on the Y-axis dashed line segment 18: set a test point at 0.1mm along the Y positive direction of the reference point, and the measured magnetic induction intensity is 778.4572𝜇T; set a test point at 0.2mm along the Y positive direction of the reference point, and the measured magnetic induction intensity is 776.2694𝜇T; set a test point at 0.1mm along the Y negative direction of the reference point, and the measured magnetic induction intensity is 782.8329𝜇T; set a test point at 0.2mm along the Y negative direction of the reference point, and the measured magnetic induction intensity is 785.0207𝜇T. Based on the above data, the variance of the Y-axis reflecting the stability of the magnetic field is calculated to be 9.5732, and the variance of the X-axis reflecting the stability of the magnetic field is 197.

[0027] like Figure 5 As shown, the inner ring radius of the double air gap circular magnetic ring is set to 20mm and the outer ring radius is set to 30mm, that is, the length of the outer radius is the same as the outer radius of the semicircular ring of the curved magnetic ring of the runway-shaped magnetic ring. At this time, the space size of the magnetic shunt area of ​​the runway-shaped magnetic ring and the circular double air gap magnetic ring in the Y-axis direction is similar. When a current of 1000A is passed through the excitation current wire, the magnetic induction intensity is measured to be 805.5070 at the second magnetic sensitive element 7 (large range detection point) located 18.7mm away 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 condition) at the second magnetic sensitive element 7 (large range detection point). T, take this point as the reference point, select appropriate test points on the Y-axis dashed line segment 21 near the reference point: set a test point at 0.1mm along the Y positive direction of the reference point, and the measured magnetic induction intensity is 805.0151𝜇T; set a test point at 0.2mm along the Y positive direction of the reference point, and the measured magnetic induction intensity is 796.9653𝜇T; set a test point at 0.1mm along the Y negative direction of the reference point, and the measured magnetic induction intensity is 797.533𝜇T; set a test point at 0.2mm along the Y negative direction of the reference point, and the measured magnetic induction intensity is 789.5590𝜇T. The variance of the Y-axis reflecting the stability of the magnetic field is calculated to be 34.6702. The inner ring radius of the double air-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 air-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 away 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, select appropriate test points near the reference point and on the X-axis dotted line segment 20: A test point was set at 0.1mm along the positive direction of X, and the magnetic induction intensity was measured to be 761.1633𝜇T; a test point was set at 0.2mm along the positive direction of X at the reference point, and the magnetic induction intensity was measured to be 747.6773𝜇T; a test point was set at 0.1mm along the negative direction of X at the reference point, and the magnetic induction intensity was measured to be 788.1353𝜇T; a test point was set at 0.2mm along the negative direction of X at the reference point, and the magnetic induction intensity was measured to be 801.6213𝜇T. The variance of the X-axis direction reflecting the stability of the magnetic field is calculated to be 363.744.

[0028] Compared with 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.

[0029] It should be particularly 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.

[0030] Example 2 In this embodiment, set Figure 1The air gap length (Y-axis direction) of the dual-range racetrack-shaped magnetic ring shown is 10mm, the air gap width (X-axis direction) is 6mm, the magnetic ring height is 20mm, the magnetic ring thickness is 10mm, the inner ring radius of the curved magnetic semicircular ring is 20mm, the outer ring radius is 30mm, the magnetic ring straight magnetic strip width is 10mm, and the magnetic ring straight magnetic strip length is 30mm; when a current of 600A to 1200A (step of 10A) is passed through the central excitation current conductor 6, at the second magnetic sensitive element 7 (large-range magnetic shunt position) 30mm away from the center of the measured current in the X-axis direction, the magnetic induction intensity linearity can be measured to be approximately 0.013795%.

[0031] set up Figure 3 The circular double air-gap magnetic ring shown has an air-gap length (Y-axis direction) of 10 mm, an air-gap width (X-axis direction) of 6 mm, a magnetic ring height of 20 mm, a magnetic ring thickness of 10 mm, an outer radius of 60 mm, and an inner radius of 50 mm. When a current of 600 A to 1200 A (in steps of 10 A) is passed through the central excitation current conductor 6, at the second magnetic sensitive element 7 (large-range magnetic shunt position) 43 mm away from the center of the measured current in the X-axis direction (a point where the magnetic induction intensity is close to the magnetic induction intensity of 780.6451𝜇T of the racetrack-shaped magnetic ring under the same current condition), the linearity of the magnetic induction intensity can be measured to be approximately 0.024695%; Set as Figure 6 The rectangular magnetic ring shown has an outer length of 80mm, an outer width of 60mm, an inner length of 60mm, an inner width of 40mm, a magnetic ring height of 20mm, and a magnetic ring thickness of 10mm; the length of the rectangular long arm is consistent with the length of the straight magnetic strip of the runway-shaped magnetic ring, and magnetic ring air gaps 15 and 17 are set in the center of the long arm, and the air gap length (Y-axis direction) is 10mm, and the air gap width (X-axis direction) is 6mm; an excitation current wire 6 is set at the central symmetrical point of the rectangular magnetic ring. In this embodiment, its large-range measurement point is located on the shunt area of ​​the line connecting 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 27.5mm (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 is selected). A second magnetic sensitive element 7 is placed at a large-range measuring point. When a current of 600A to 1200A (in steps of 10A) flows through the central excitation current conductor 6, the linearity of the magnetic induction intensity measured at the second magnetic sensitive element 7 is about 0.046431%.

[0032] Comparing the linearity 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 of the present invention has a greater advantage in linearity.

[0033] 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; the outer length and inner length of the rectangular magnetic ring also do not include the air gap width.

[0034] Example 3 The size of the dual-range racetrack-shaped magnetic ring in this embodiment is basically consistent with that in Embodiment 1, with the difference that: the air gap width is different; the excitation current wire 6 is located at the center of the racetrack-shaped magnetic ring, the current is set to 10A, and the air gap width is changed: when the air gap width is 2mm, the magnetic induction intensity at the first magnetic sensitive element is 3138.0269𝜇T; when the air gap width is 4mm, the magnetic induction intensity at the first magnetic sensitive element is 1569.5371𝜇T; when the air gap width is 6mm, the magnetic induction intensity at the first magnetic sensitive element is 1046.4584𝜇T; when the air gap width is 8mm, the magnetic induction intensity at the first magnetic sensitive element is 780.0508𝜇T.

[0035] It can be concluded that the smaller the air gap width on the runway-shaped magnetic ring, the better the magnetic field concentration effect. The specific implementation process should comprehensively consider 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, and the air gap width should be selected as a compromise. The generally selected width is between 2mm and 15mm.

[0036] Example 4 The size of the dual-range runway-shaped magnetic ring in this embodiment is basically consistent with that in Embodiment 1, with the difference that: the size of the magnetic ring is different; when the current passing through the excitation current wire is 10A, when the size of the magnetic ring is an inner ring radius of 20mm and an outer ring radius of 30mm, the magnetic induction intensity at the first magnetic sensitive element is 1046.4584𝜇T; when the size of the magnetic ring is an inner ring radius of 30mm and an outer ring radius of 40mm, the magnetic induction intensity at the first magnetic sensitive element is 1044.6991𝜇T; when the size of the magnetic ring is an inner ring radius of 40mm and an outer ring radius of 50mm, the magnetic induction intensity at the first magnetic sensitive element 4 is 1045.9764𝜇T.

[0037] When the current passing through the excitation current wire is 1000A, when the magnetic ring size is an inner ring radius of 20mm, an outer ring radius of 30mm, and a straight magnetic strip length of 30mm, the magnetic induction intensity at the second magnetic sensitive element 30mm away from the center of the wire (the center of the curved magnetic semicircle ring is selected as the measuring point) is 780.6451𝜇T; when the magnetic ring size is an inner ring radius of 30mm, an outer ring radius of 40mm, and a straight magnetic strip length of 40mm, the magnetic induction intensity at the second magnetic sensitive element 40mm away from the center of the wire (the center of the curved magnetic semicircle ring is selected as the measuring point) is 795.9005𝜇T; when the magnetic ring size is an inner ring radius of 40mm, an outer ring radius of 50mm, and a straight magnetic strip length of 50mm, the magnetic induction intensity at the second magnetic sensitive element 7 50mm away from the center of the wire (the center of the curved magnetic semicircle ring is selected as the measuring point) is 716.6806𝜇T.

[0038] It can be seen from this embodiment that the appropriate magnetic ring size and the appropriate current detection point (magnetic sensitive element placement point) can be selected according to the working range of the magnetic sensitive element and the range of the excitation current. In this embodiment, through comprehensive consideration, the inner ring radius of the magnetic ring can be 5mm to 50mm, the outer ring radius of the magnetic ring can be 15mm to 100mm, 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 semicircular ring.

[0039] Application Example 1 The racetrack-shaped magnetic ring is fixedly assembled into the insulating mold, such as Figure 7As shown, two PCB probe boards 22 and 23 with integrated TMR sensor chips and in-situ feedback coils are inserted into the predetermined 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. The measured current is passed through the signal conductor 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 gathered by the magnetic ring at the air gap of the magnetic ring, forming a larger magnetic field, and at the same time forming a smaller magnetic field at the magnetic shunt. The magnetic sensitive axes of the magnetic sensitive elements on the two probe boards are respectively in the same direction as the main components of the magnetic induction intensity of the measured magnetic field at the measuring point. The magnetic sensitive elements detect the magnetic field signal and output the voltage in the form of differential, which is sent to the instrument amplifier 24 or 25 through switching devices such as relays; the instrument 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 is stabilized at a smaller value. The current signal on the feedback coil is connected in series with the sampling power resistor 27 to convert the current signal into a voltage signal. The analog voltage signal is converted into a digital signal through the instrument amplifier 28 and the ADC. After MCU data processing and calibration, the value of the current to be measured can be obtained through the value of the voltage signal. At the same time, the SPI communication is used to output to the host computer on the PC for display, so that the amplitude and frequency of the current to be measured can be displayed and monitored in real time on the host computer.

[0040] The high-precision small-range current detection and high-stability large-range current detection described in this embodiment are implemented in a single magnetic ring structure, and the signals of the two ranges can be measured independently and 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 distinguishes data of different ranges, that is, it merges large and small range data, which solves the problem that the two independent ranges have limitations in environmental applicability, and fully utilizes the advantages of high sensitivity and high resolution of the small range, while giving full play to the advantages of superior range performance of the large range.

[0041] This embodiment combines magnetic shunting and magnetic gathering technology, magnetic sensor technology, and adopts a closed-loop structure and in-situ feedback technology to offset the magnetic field signal generated by the primary current to achieve a magnetic balance state, further improving the system's operating range, sensitivity, etc. And only one racetrack-shaped magnetic ring structure is used to complete the current measurement of two ranges, greatly saving cost and volume.

[0042] The dual-range racetrack-shaped magnetic ring is made of soft magnetic materials such as silicon steel, Permalloy or iron-based amorphous.

[0043] The magnetic sensitive element is an anisotropic magnetoresistance sensor chip, a Hall sensor chip, a giant magnetoresistance sensor chip or a tunnel junction magnetoresistance sensor chip.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A dual-range racetrack-shaped magnetic ring for a current sensor, characterized in that: It is a symmetrical double "U"-shaped structure, and each side of the "U"-shaped structure includes a curved magnetic semicircular ring and two straight magnetic strips arranged at both ends of the curved magnetic semicircular ring; an air gap is arranged between the two oppositely 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, which is used for the current sensor to detect large-range current.

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

3. The dual-range racetrack-shaped magnetic ring for current sensor according to claim 1, characterized in that: The straight magnetic strip and the curved magnetic semicircular ring are split structures.

4. The dual-range racetrack-shaped magnetic ring for current sensor according to claim 1, characterized in that: 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 semicircular ring.

5. The dual-range racetrack-shaped magnetic ring for current sensor according to claim 1, characterized in that: The racetrack-shaped magnetic ring is made of soft magnetic material.

6. The dual-range racetrack-shaped magnetic ring for current sensor according to claim 5, characterized in that: The racetrack-shaped magnetic ring is made of soft magnetic thin strip material through a laminated structure.

7. Application of the dual-range racetrack-shaped magnetic ring as described in any one of claims 1 to 6 in a current sensor; when measuring small-range current, the racetrack-shaped magnetic ring exhibits a better magnetic focusing effect on the magnetic field signal generated by the measured current in the air gap at the middle end of the two straight magnetic strip parts of the magnetic ring, and has higher resolution and sensitivity; and 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 current, the racetrack-shaped magnetic ring has a stronger magnetic shunting effect on the magnetic field signal from the center of the magnetic ring to the magnetic ring, thereby expanding the large-range current detection range, while having better linearity and smaller size.

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