Design method of wide-range current sensor based on magnetism induction effect and sensor

Abstract

A kind of design method and sensor of wide-range current sensor based on magnetomotive effect, in the method, magnetomotive body is provided and the magnetomotive body is arranged between energized conductor and magnetic field sensor sensing chip;The magnetic flux density at the position of the magnetic field sensor sensing chip is reduced by the magnetomotive effect of the magnetomotive body, so that the magnetic field sensor sensing chip remains linear response in wide current range, and wide-range current measurement is realized.By the action of high magnetic permeability magnetomotive body, the magnetic flux density at the position of TMR sensing chip is significantly weakened, so that the sensor magnetic saturation phenomenon is effectively delayed.The method significantly widens the current measurement range of the sensor under the premise of maintaining small size, and realizes the breakthrough of traditional TMR current sensor in wide-range measurement field.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a design method and sensor for a large-range current sensor based on the magnetization effect. Background Technology

[0002] In recent years, with the rapid development of new power systems such as large-capacity AC / DC hybrid transmission and distribution and distributed multi-energy intelligent networking, the demand for operation monitoring of high-power systems in my country's industrial applications and urban power grids has become increasingly urgent. Current sensing and measurement devices in various nodes and switching equipment of the power system are facing new demands and challenges that are completely different from traditional scenarios. Traditional large-range detection methods for large currents (>1 kA) have certain limitations in terms of application scenarios and performance. Intrusive measurement with shunts causes serious heat generation under high current; Rogowski coils and current transformers are bulky and cannot measure DC; fiber optic current sensors, although having excellent performance, are complex in structure and expensive, making them unsuitable for large-scale use; Hall current sensors are sensitive to the environment and have poor sensitivity and linearity. In recent years, current sensors based on the tunnel magnetoresistance (TMR) effect, with their high sensitivity, low power consumption, and excellent small-size integration potential, have been regarded as an ideal solution for the next generation of current sensors, and are expected to meet the comprehensive requirements of non-invasive, large-range, AC / DC compatible, low-cost, small-size, and wide-bandwidth large current sensing.

[0003] Current research on TMR current sensors, besides exploring micro / nano fabrication processes and innovating the performance of their internal magnetoresistive materials, primarily focuses on the design of traditional non-invasive TMR current sensors. This research mainly involves innovatively combining the design principles of magnetic concentrators, arrays, open-loop, and closed-loop designs to adapt to different current detection needs. A TMR current sensing scheme with three metal shielding arcs has been used to measure large currents in gas-insulated switchgear. Studies show that for a 1 kA current measurement, the sensor's response deviation is 0.83%, demonstrating good noise immunity and linearity. However, this method is limited to current measurements with fixed conductors, resulting in low flexibility. Magnetic concentrators increase the magnetic field strength of the TMR sensing unit at the air gap to improve current measurement sensitivity through the magnetic concentrator effect. Open-loop array structures increase the sensor's anti-interference capability by evenly distributing the error. However, due to the material properties of TMR sensors, their linear magnetic field range is typically less than 0.1 T. When the magnetic field exceeds this range, a non-linear output attenuation occurs, increasing the measurement error. Therefore, the saturation problem caused by the large magnetic field generated by large currents makes it difficult for TMR current sensors using traditional magnetic field concentrators and open-loop array designs to exceed the 1 kA range within a practical volume. For example, under a current of 10 kA, according to the formula for the magnetic field distribution around an infinitely long straight conductor: B = µ0I / 2πr, it can be seen that to avoid saturation of the TMR sensor chip, the radius r of its distance from the center of the conductor must be greater than 20 cm. This means that to measure 10 kA within the linear response range of 0.1 T of the TMR current sensor, the diameter of the array current sensor would be 40 cm, resulting in an extremely large volume that is no longer practical. While closed-loop negative feedback can extend the linear range of the TMR sensor to some extent, achieving the zero flux principle under the large magnetic field caused by a large current requires extremely high feedback power consumption, still making large current measurement impossible. Therefore, although the TMR current sensor has significant advantages in sensitivity, power consumption, and integration, the inherent flaws in existing design methods mean that it remains a blank in the field of large current measurement above the kA level, with a severely limited range.

[0004] Existing sensor technologies have limited measurement ranges and cannot meet the requirements for high-current measurements above the kA level: Existing TMR current sensors are limited by the linear magnetic field range of the material (typically <0.1 T), and are prone to saturation under high currents, leading to a significant increase in measurement errors. For example, to avoid saturation at 10 kA current, the sensor diameter needs to be over 40 cm, which is too large and impractical, and the design principle has inherent flaws. Traditional designs such as magnetic rings and open-loop arrays can improve sensitivity or anti-interference capabilities, but they cannot fundamentally solve the saturation problem under large magnetic fields, making it difficult to achieve a large range while maintaining a small size. Closed-loop feedback methods have high power consumption and are difficult to implement practically: Although closed-loop negative feedback can extend the linear range, it requires extremely high power consumption to achieve "zero magnetic flux" under high currents, making it unsuitable for practical high-current measurement scenarios. There is a gap in existing technology in the field of high-current measurement; currently, there is no TMR current sensor solution that can achieve small size, high accuracy, and low power consumption above the kA level.

[0005] The information disclosed in the background section is only for enhancing the understanding of the background of this invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] This invention provides a design method and sensor for a large-range current sensor based on the magnetization effect, which significantly expands the current measurement range while maintaining a small sensor size.

[0007] A design method for a large-range current sensor based on the magnetization effect includes:

[0008] A magnet is provided and the magnet is disposed between a current-carrying conductor and a magnetic field sensor chip;

[0009] The magnetic flux density at the location of the magnetic field sensor chip is reduced by the magnetic attraction effect of the magnetizer, so that the magnetic field sensor chip can maintain a linear response over a wide current range and realize large-range current measurement.

[0010] In the aforementioned design method for a large-range current sensor based on the magnetizing effect, the formula for calculating the magnetic flux gain k of the magnetizing effect is as follows:

[0011] Where B1 represents the magnetic induction intensity generated by the current-carrying conductor at the location of the magnetic field sensor chip when no magnet is used, and B2 represents the magnetic induction intensity of the current-carrying conductor at the location of the magnetic field sensor chip when a magnet is used.

[0012] In the design method of a large-range current sensor based on the magnetizing effect, the parameters of the magnetizing body, including the inner radius d1, outer radius d2, thickness d3, and radian θ, satisfy the following conditions:

[0013] As the width of the magnet, δd = d2 - d1, increases, the magnetic reluctance, R... m As the magnetic field strength decreases, the magnetic field gain k decreases, and the saturation current increases.

[0014] As the thickness d3 of the magnet increases, the magnetic reluctance R m As the magnetic field strength decreases, the magnetic circuit gain k decreases;

[0015] Increasing the arc θ of the magnetizer reduces the air gap, enhancing the magnetizing effect at the inner probe point and decreasing the magnetic circuit gain k.

[0016] In the design method of a large-range current sensor based on the magnetizing effect, the magnets are arranged in a ring with uniform intervals of 120° to form a three-array structure.

[0017] In the design method of a large-range current sensor based on the magnetizing effect, the magnet is made of cobalt-based amorphous alloy with an inner radius of 35 mm, an outer radius of 50 mm, a thickness of 15 mm, and an arc of 45°.

[0018] In the aforementioned design method for a large-range current sensor based on the magnetization effect, the magnetic field sensor includes a TMR current sensor, a Hall sensor, an AMR sensor, and a GMR magnetic field sensor.

[0019] In the aforementioned design method for a large-range current sensor based on the magnetizing effect, the TMR sensing chip is arranged 32 mm away from the center of the current-carrying conductor from the inner side of the center of the magnetizing body. The three TMR sensing chips form a ring array and are connected in parallel. The three magnetizing bodies of the TMR sensing chips are arranged in a ring to form a three-array structure.

[0020] A current sensor, characterized in that it is constructed via the aforementioned large-range current sensor design method based on the magnetizing effect.

[0021] The current sensor has a diameter of 15 cm, a range of 30 kA, and a relative measurement error of less than ±0.8%.

[0022] In the current sensor, the ring array of the magnetic field sensor chip is fed into the AD sampling after differential amplification and signal conditioning, and the data is processed by the MCU to finally output the measured current value.

[0023] Compared with existing technologies, this invention has the following advantages: By creating a "negative flux gain" around a high-permeability magnet, this invention significantly reduces the magnetic flux density at the TMR sensor chip, effectively delaying saturation and breaking through the range limitations of traditional TMR sensors. It achieves large-range measurement in a small volume: Achieving a large range of 30 kA in a sensor with a diameter of only 15 cm, balancing high integration and practicality, and solving the problem of excessively large size in traditional designs. It combines high precision and low error: The relative measurement error is less than ±0.8% within the range of 0.1–31 kA, maintaining good measurement accuracy while ensuring a large range. It is applicable to various magnetic field sensors and array numbers: The magnetizing effect design concept is not limited to TMR sensors but can also be extended to other magnetic field sensors such as Hall effect, AMR, and GMR. Furthermore, different array numbers can be used according to current measurement requirements, demonstrating good technical versatility. It enhances anti-interference capabilities: The magnet also has a magnetic field shielding effect, improving the sensor's anti-interference performance in complex electromagnetic environments. Attached Figure Description

[0024] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0025] In the attached diagram:

[0026] Figure 1 This is a schematic diagram of a three-array large-range TMR current sensor designed based on the magnetization effect according to the present invention;

[0027] Figure 2 This is a physical image of the three-array large-range TMR high-current sensor of the present invention;

[0028] Figure 3 This is a schematic diagram of the magnetizing effect of the present invention. Figure 3 (a) Schematic diagram of the conceptual model of magnetic flux density change due to magnetization effect. Figure 3 (b) Schematic diagram of the equivalent model of the magnetic circuit principle of the magnetic attraction effect;

[0029] Figure 4 This is a schematic diagram of the simulation model of the three-array magnet for finite element magnetic field analysis of this invention. Figure 4 (a) Three-dimensional view, Figure 4 (b) Two-dimensional view;

[0030] Figure 5This is a schematic diagram of the magnetic field simulation results of the three-array magnetizer of the present invention;

[0031] Figure 6 This is a schematic diagram showing the comparison of magnetic flux density and magnetic flux gain calculation results at position a of the cut-off line in this invention, with and without a magnetizing element.

[0032] Figure 7 This is a schematic diagram illustrating the effect of changes in the magnet structure parameters on the magnetic circuit gain and saturation of the present invention.

[0033] Figure 8 This is a schematic diagram of the measurement results of the large-range TMR current sensor of the present invention under a large current of 28 kA;

[0034] Figure 9 This is a schematic diagram showing the measurement output and relative error of the large-range TMR current sensor of the present invention. Figure 9 (a) 0-1kA; Figure 9 Medium (b) 1-31 kA.

[0035] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0036] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0037] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0038] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0039] like Figures 1 to 9 As shown, the design method for a large-range current sensor based on the magnetization effect includes the following steps:

[0040] A magnet is provided and the magnet is disposed between a current-carrying conductor and a magnetic field sensor chip;

[0041] The magnetic flux density at the location of the magnetic field sensor chip is reduced by the magnetizing effect of the magnetizer, allowing the magnetic field sensor chip to maintain a linear response over a large current range, thus enabling large-range current measurement. In the current sensor, the large range refers to measuring currents greater than 1 kA.

[0042] In a preferred embodiment of the design method for a large-range current sensor based on the magnetizing effect, the magnetic flux gain k of the magnetizing effect is preferably calculated using the following formula:

[0043] Where B1 represents the magnetic induction intensity generated by the current-carrying conductor at the location of the magnetic field sensor chip when no magnet is used, and B2 represents the magnetic induction intensity of the current-carrying conductor at the location of the magnetic field sensor chip when a magnet is used.

[0044] In a preferred embodiment of the design method for a large-range current sensor based on the magnetizing effect, the parameters of the magnetizing body, including the inner radius d1, outer radius d2, thickness d3, and radian θ, satisfy the following conditions:

[0045] As the width of the magnet, δd = d2 - d1, increases, the magnetic reluctance, R... m As the magnetic field strength decreases, the magnetic field gain k decreases, and the saturation current increases.

[0046] As the thickness d3 of the magnet increases, the magnetic reluctance R m As the magnetic field strength decreases, the magnetic circuit gain k decreases;

[0047] Increasing the arc θ of the magnetizer reduces the air gap, enhancing the magnetizing effect at the inner probe point and decreasing the magnetic circuit gain k.

[0048] In a preferred embodiment of the design method for a large-range current sensor based on the magnetizing effect, the magnets are arranged in a ring at uniform intervals of 120° to form a three-array structure.

[0049] In a preferred embodiment of the design method for a large-range current sensor based on the magnetizing effect, the magnetizing body is made of a cobalt-based amorphous alloy with an inner radius of 35 mm, an outer radius of 50 mm, a thickness of 15 mm, and an arc of 45°.

[0050] In a preferred embodiment of the design method for a large-range current sensor based on the magnetization effect, the magnetic field sensor includes a TMR current sensor, a Hall sensor, an AMR sensor, and a GMR magnetic field sensor.

[0051] In a preferred embodiment of the design method for a large-range current sensor based on the magnetizing effect, the TMR sensing chip is arranged 32 mm away from the center of the current-carrying conductor from the inner side of the center of the magnetizing body. The three TMR sensing chips form a ring array and are connected in parallel. The three magnetizing bodies of the TMR sensing chips are arranged in a ring to form a three-array structure.

[0052] A current sensor is constructed using the aforementioned large-range current sensor design method based on the magnetizing effect.

[0053] The current sensor has a diameter of 15 cm, a range of 30 kA, and a relative measurement error of less than ±0.8%.

[0054] In the current sensor, the ring array of the magnetic field sensor chip is fed into the AD sampling after differential amplification and signal conditioning, and the data is processed by the MCU to finally output the measured current value.

[0055] In one embodiment, the method significantly reduces the magnetic flux density B at the location of the TMR sensor under high current by shunting the magnetic flux of the magnet, thereby greatly improving the linear measurement range of the sensor and providing a new technical route and methodological strategy for the design of large-range TMR current sensors.

[0056] The structural principle diagram of the three-array large-range TMR current sensor designed based on the magnetization effect of this invention is shown below. Figure 1 As shown. The magnetizing element is made of a cobalt-based amorphous alloy with high magnetic permeability. Three magnetizing elements are evenly spaced at 120° intervals, with an arc of 45°. The inner radius d1 = 35 mm, the outer radius d2 = 50 mm, and the thickness d3 = 15 mm. The TMR sensor chip is positioned 32 mm from the center of the conductor, inside the center of the magnetizing element. The three TMR linear magnetic field sensor chips are connected in parallel in a ring array. The output is differentially amplified and signal-conditioned before being input to an AD converter for sampling. The MCU processes the data and finally outputs the measured current value. The reliable fixation of the magnetizing element and the TMR sensor position directly determines the long-term stability of the sensor's measurement performance. Therefore, this invention uses an integrated slot on the PCB circuit board to prevent the magnetizing element from shifting during operation, ensuring the relative fixation of the TMR sensor chip and the magnetizing element. The final packaged large-range TMR current sensor is shown in the following figure. Figure 2 As shown, the conductor can be snapped into the center of the sensor. This sensor has a diameter of only 15 cm, a range of 30 kA, and a relative error of less than 1%. The following details the principle of the magnetization effect, simulation analysis, and the actual measurement output curve of the sensor.

[0057] The magnetic flux gain k is defined as a parameter to represent the magnitude of the magnetizing effect, and its calculation formula is as follows:

[0058] (1)

[0059] Where B1 represents the magnetic flux density generated by the current-carrying conductor at the TMR sensor chip location without the use of a magnetizer; B2 represents the magnetic flux density at the TMR sensor chip location with the use of a magnetizer. When B2 is less than B1, the magnetic flux density at the TMR sensor chip location is reduced compared to the magnetic flux density in a traditional open-loop array design without a magnetizer. Under the fixed saturation magnetic field conditions of the TMR sensor chip, this increases the linear measurement current range of the TMR sensor chip, and the magnetizing effect occurs.

[0060] The magnetizing effect of the magnetizing body is further analyzed and derived using magnetic circuit theory. In a linear magnetic circuit with constant permeability, magnetic circuit theory and circuit theory share similarities. A simplified current-carrying conductor generates a uniform and parallel magnetic field with magnetic flux density B1 in a certain vacuum region. The relationship between the magnetic flux and magnetic flux density in this region is expressed as:

[0061] (2)

[0062] Where Φ represents magnetic flux, H represents magnetic field strength, F represents magnetomotive force, µ0 is the permeability of air, l is the length of the magnetic path, and S is the normal cross-sectional area of ​​the magnetic path. F acts as the driving force of the magnetic field, similar to voltage in a circuit; magnetic flux (Φ) represents the total magnetic flux flowing through the magnetic path, similar to current; and the magnetic reluctance (R) that opposes the magnetic flux through the magnetic path... m Similar to a resistor, its expression is:

[0063] (3)

[0064] Where l is the length of the magnetic circuit, µ is the permeability of the material placed in the magnetic circuit, and S is the normal cross-sectional area of ​​the magnetic circuit. For example... Figure 3 As shown in (a), when a rectangular magnet is placed in the center of the region, with air domains of equal length and width above and below, according to the linear magnetic circuit theory and formula (3), the magnetic reluctance R MFD With two R air Parallel connection, such as Figure 3 As shown in (b). Due to the cobalt-based amorphous alloy of the magnet having a permeability μ r Since the magnetic reluctance R is much greater than the permeability μ0 of air, and their magnetic circuit l and cross-sectional area S are the same, then their magnetic reluctance R... MFD Much smaller than R air Therefore Φ MCF >Φ airAccording to the law of conservation of magnetic flux, when the magnetic flux density in a magnet increases, the magnetic flux density in the air above and below it must decrease. This invention defines this phenomenon as the magnetizing effect. It can be seen that when a high-permeability magnet is placed in a magnetic field, its internal magnetic flux density increases, but the magnetizing effect disperses the magnetic flux density around the position of the magnet perpendicular to the magnetic field direction, ensuring the conservation of magnetic flux throughout the entire region.

[0065] In the air domain, the gain B2 with a magnet is less than the gain B1 without a magnet. At this point, the magnetic flux density gain k < 0, which is negative and can also be called negative magnetic flux density gain. The smaller k is, the stronger the magnetizing effect; the larger k is, the weaker the magnetizing effect. However, k cannot be greater than or equal to 0; it can only approach 0 infinitely. Therefore, utilizing the negative magnetic circuit gain characteristic based on the magnetizing effect, magnets can be designed in environments with large magnetic fields generated by large currents to mitigate TMR sensor chip saturation and achieve a larger current measurement range in a small volume.

[0066] Finite element method (FEM) simulation was used to further analyze the influence of the structural parameters of the magnetizer on the magnetizing effect under the large magnetic field generated by a large current in a current-carrying conductor. The constructed three-dimensional simulation model is as follows: Figure 4 As shown, the cross-section of the magnet is perpendicular to the normal of the annular magnetic field generated by the conductor. d1 and d2 are the inner and outer radii of the magnet, respectively. δd = d2 - d1 is the width of the magnet. θ is the radian of the center of the magnet, the size of which affects the size of the air gap between the three arrays of magnets. d3 is the thickness of the magnet.

[0067] When the current in the circular conductor is 10 kA, θ = 45°, d1 = 35 mm, d2 = 50 mm, and d3 = 15 mm, the simulated magnetic flux density results are as follows: Figure 5 As shown, the comparison of magnetic flux density with and without a magnet at the one-dimensional slit a and the calculated magnetic flux gain are as follows: Figure 6 As shown, the results indicate that, due to the magnetizing effect, the magnetic flux density at distances of 25 mm-35 mm and 50 mm-70 mm from the conductor center is significantly lower than the magnetic field strength without a magnet. The magnetic flux gain k is negative, and the magnetizing effect is more pronounced the closer to the magnet. There is no significant difference in the magnetizing effect between the inner and outer sides of the magnet. Therefore, the TMR sensor chip can be placed inside the magnet to reduce the sensor size. At the same time, the magnet has a magnetic field shielding effect, which can increase the anti-interference capability of the TMR sensor chip. The location of the magnet at 35 mm-50 mm from the conductor center shows a significantly higher magnetic flux density than without a magnet. These results further verify the magnetic circuit theory and magnetizing effect mentioned in the above magnetic circuit theory analysis.

[0068] With d1 = 35 mm kept constant, the shape parameters d2, d3, and θ of the magnet were varied to investigate their impact on the magnetic circuit gain. A magnetic field probe, representing the TMR sensor chip, was positioned 32 mm from the center of the conductor. The magnetic circuit gain at this location, with and without the magnet, was calculated. The results are as follows: Figure 7 As shown, when the magnet is not saturated and the magnetic field is low frequency, its effective permeability can be considered constant. At this time, the magnetic circuit gain is constant, and the magnetic field at the sensor location is proportional to the magnitude of the measured current. When the magnet is saturated, the effective permeability decreases significantly, the magnetic reluctance increases accordingly, the magnetizing effect weakens, and the magnetic circuit gain k increases and tends to 0.

[0069] Simulation results show that changes in the spatial magnetic circuit and magnetic reluctance lead to variations in the strength of the magnetizing effect and the shift in the saturation current. Increasing the width d2 and thickness d3 of the magnetizer increases the core cross-sectional area S and the magnetic reluctance R. m Decreasing the radius θ of the magnetizer enhances the magnetizing effect, reduces the magnetic circuit gain k, and increases the saturation current. Increasing the radius θ of the magnetizer leads to a smaller air gap, making the magnetizer more prone to saturation, but it also reduces magnetic reluctance and enhances the magnetizing effect at the inner probe point, thus decreasing the magnetic circuit gain k. Since the magnetic field generated by a circular conductor is inversely proportional to its distance from the center, the strength of the magnetizing effect and the shift of the saturation point do not change linearly with the structural parameters of the magnetizer. Therefore, when designing a current sensor using this principle, it is necessary to comprehensively consider the material properties of the magnetizer and the number of arrays to achieve a balance between the sensor's target range, sensitivity, and size.

[0070] To verify the performance of the TMR high-current sensor based on the magnetization effect, the sensor's measurement output when the peak half-wave current of the current-carrying conductor is 28kA is as follows: Figure 8 As shown. The linear output and relative measurement error of the TMR high-current sensor under small currents of 0-1 kA and large currents of 1 kA-31 kA are as follows. Figure 9 (a) and Figure 9 As shown in (b). The results show that the TMR current sensor developed based on the magnetization effect of this invention has a relative measurement error of less than ±0.8% under currents of 0.1-31 kA. The measurement error increases when the measured current is less than 100 A, and the measurement error is 5% at 30 A.

[0071] Furthermore, this invention fundamentally solves the range limitation problem faced by TMR current sensors in the field of high-current measurement through the "magnetizing effect." Specifically, this technology uses a high-permeability magnet (such as a cobalt-based amorphous alloy) placed between the current-carrying conductor and the TMR sensor chip. Utilizing the negative flux gain characteristic in magnetic circuit theory, it significantly reduces the magnetic flux density at the location of the TMR sensor chip. According to magnetic circuit theory, the magnetic reluctance of the high-permeability magnet is much smaller than that of air, causing the magnetic flux to concentrate inside the magnet. The magnetic flux density around the position perpendicular to the magnetic field direction of the magnet decreases accordingly, forming a "negative flux density gain." This magnetizing effect allows the TMR sensor chip to remain within the linear magnetic field range even under high current, effectively delaying the sensor's magnetic saturation phenomenon. By rationally designing the geometric parameters of the magnet (inner radius d1, outer radius d2, thickness d3, and radian θ), the magnitude of the magnetic circuit gain k can be precisely controlled: increasing the width δd and thickness d3 of the magnet reduces the magnetic reluctance R. m The increased radian angle θ, while making the magnetizer more prone to saturation, reduces magnetic reluctance and enhances the magnetizing effect at the inner probe point. This invention employs a three-array structure design, with three magnetizers evenly spaced at 120° intervals. The TMR sensor chip is positioned 32 mm from the center of the conductor, inside the center of the magnetizer. This allows for a large-range measurement of 30 kA with a sensor diameter of only 15 cm, with a relative error of less than ±0.8%. Compared to traditional magnetic ring designs (requiring a diameter of over 40 cm to measure 10 kA current) and closed-loop negative feedback methods (requiring extremely high feedback power consumption under high current), this technical solution achieves high-precision measurement of currents above the kA level while maintaining a small size, breaking through the technical bottleneck of TMR sensors in the field of high-current measurement. Furthermore, the magnetic shielding effect of the magnetizer enhances the sensor's anti-interference capability in complex electromagnetic environments, giving the design good versatility and scalability, and allowing it to be extended to large-range current measurement applications of other magnetic field sensors such as Hall effect, AMR, and GMR.

[0072] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A design method for a large-range current sensor based on the magnetization effect, characterized in that, Includes the following steps: A magnet is provided and the magnet is disposed between a current-carrying conductor and a magnetic field sensor chip; The magnetic flux density at the location of the magnetic field sensor chip is reduced by the magnetic attraction effect of the magnetizer, so that the magnetic field sensor chip can maintain a linear response over a wide current range and realize large-range current measurement.

2. The design method for a large-range current sensor based on the magnetizing effect as described in claim 1, characterized in that, Preferably, the formula for calculating the magnetic flux gain k of the magnetizing effect is: Where B1 represents the magnetic induction intensity generated by the current-carrying conductor at the location of the magnetic field sensor chip when no magnet is used, and B2 represents the magnetic induction intensity of the current-carrying conductor at the location of the magnetic field sensor chip when a magnet is used.

3. The design method for a large-range current sensor based on the magnetizing effect according to claim 1, characterized in that, The parameters of the magnetizer, including the inner radius d1, outer radius d2, thickness d3, and radian θ, are designed to meet the following conditions: As the width of the magnet, δd = d2 - d1, increases, the magnetic reluctance, R... m As the magnetic field strength decreases, the magnetic field gain k decreases, and the saturation current increases. As the thickness d3 of the magnet increases, the magnetic reluctance R m As the magnetic field strength decreases, the magnetic circuit gain k decreases; Increasing the arc θ of the magnetizer reduces the air gap, enhancing the magnetizing effect at the inner probe point and decreasing the magnetic circuit gain k.

4. The design method for a large-range current sensor based on the magnetizing effect as described in claim 1, characterized in that, The magnets are arranged in a ring at uniform intervals of 120°, forming a three-array structure.

5. The design method for a large-range current sensor based on the magnetizing effect according to claim 1, characterized in that, The magnet is made of cobalt-based amorphous alloy with an inner radius of 35 mm, an outer radius of 50 mm, a thickness of 15 mm, and an arc of 45°.

6. The design method for a large-range current sensor based on the magnetizing effect according to claim 1, characterized in that, Magnetic field sensors include TMR current sensors, Hall effect sensors, AMR sensors, and GMR magnetic field sensors.

7. The design method for a large-range current sensor based on the magnetizing effect according to claim 1, characterized in that, The TMR sensor chip is positioned 32 mm from the center of the current-carrying conductor, inside the center of the magnet. The three TMR sensor chips form a ring array and are connected in parallel. The three magnets that are aligned with the TMR sensor chips are arranged in a ring to form a three-array structure.

8. A current sensor, characterized in that, It is constructed by any one of the magnetic attraction effect-based large-range current sensor design methods according to claims 1-7.

9. The current sensor according to claim 8, characterized in that, The current sensor has a diameter of 15 cm, a range of 30 kA, and a relative measurement error of less than ±0.8%.

10. The current sensor according to claim 8, characterized in that, The ring array of the magnetic field sensor chip is fed into an AD sampler after differential amplification and signal conditioning. The data is then processed by the MCU, and the measured current value is finally output.

Images