Hall current sensor based on tunnel magnetoresistance composite correction

Abstract

The invention provides a Hall current sensor based on tunnel magnetoresistance composite correction, and the sensor comprises an annular supporting structure which is used for sleeving the periphery of a to-be-measured circular-section conductor; the TMR sensors are mounted on the annular supporting structure and are symmetrically distributed around the conductor; the current Hall sensor is located on an adjacent plane; the TMR sensor comprises a high-permeability magnetic shunt and a tunnel magnetoresistor TMR; the differential detection circuit is used for carrying out differential processing on output signals of the TMR sensors at symmetrical positions; and the data processing unit is electrically connected with the TMR sensor and the current Hall sensor. The tunnel magnetoresistors and the Hall sensor are arranged in adjacent planes, and on the premise that sampling of the Hall sensor is not affected, the inertial delay characteristic of the tunnel magnetoresistors in the adjacent planes is used for capturing current transient changes and detecting weak magnetic field changes, and a phase correction time reference is provided for inherent phase delay of the Hall sensor.

Description

Technical Field

[0001] This invention relates to the field of current detection sensor technology, and specifically to a Hall current sensor based on tunnel magnetoresistive composite correction. Background Technology

[0002] In nuclear fusion devices (such as tokamak), closed-loop power supply control is crucial for controlling plasma equilibrium and configuration. Operating in strong magnetic fields and high current environments demands extremely high accuracy in current sampling and low phase delay. In such environments, Hall effect current sensors, with their electrical isolation, wide measurement range, and interference resistance, along with their progressive degradation characteristics, have consistently been the mainstream choice for measuring power supply current in nuclear fusion devices, ensuring reliability. The Hall effect element operates by generating voltage through the deflection of charge carriers under the Lorentz force. However, the migration speed of charge carriers in semiconductor materials has an upper limit, resulting in physical delay. This can easily create a vicious cycle of "delay-deviation amplification" in closed-loop power supply control. In strong magnetic fields, misalignment of the Hall effect element's installation position will degrade the linearity of the Hall output. Furthermore, changes in radiation can cause sensitivity drift in the Hall effect element, posing a challenge to the long-term stable operation of the power supply system.

[0003] The physical essence of tunnel magnetoresistive (TMR) is the electron tunneling process. Its extremely low inertial delay (timescale on the femtosecond level) enables TMR to accurately capture transient changes in current. The sensitivity of TMR is 100-1000 times that of Hall elements, and the signal-to-noise ratio is ≥60dB under weak magnetic fields. This makes TMR more capable of capturing and detecting weak magnetic field changes in real time compared to Hall elements. TMR can achieve differential measurement through a ring-shaped symmetrical layout. The current conductor should coincide with the axis of the magnetic ring. When the installation position is off-center, the magnitude of the magnetic field change of the symmetrical elements is equal and the direction is opposite. The differential output can cancel the influence of the deviation, thus providing a magnetic field reference for the current Hall and compensating for the stringent installation accuracy requirements of Hall sampling. TMR has better zero magnetic field output drift (≤1mV / ℃) and hysteresis (≤0.1%) than Hall, which can provide a stable calibration reference for Hall and suppress accuracy drift during long-term use. In nuclear fusion engineering, current detection devices need to meet the requirement of degraded operation after single-point failure of current detection. Under extreme conditions, TMR may cause breakdown of the magnetic tunnel junction barrier layer and suffer irreversible damage, making it difficult to meet the reliability requirements and unsuitable as an independent main current detection device. Therefore, it is essential to provide a Hall current sensor based on tunnel magnetoresistive composite correction that meets the safety specifications for power current detection in nuclear fusion devices and improves current detection performance to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a Hall current sensor based on tunnel magnetoresistive composite correction, suitable for the power safety and control requirements of nuclear fusion devices. It aims to utilize existing tunnel magnetoresistive (TMR) and magnetic shunt technologies to apply the TMR in a strong magnetic field environment (attenuating to the linear region), thereby reducing the output linearity degradation caused by Hall current installation deviations and improving measurement accuracy; it also reduces the phase delay of large current measurements due to the Hall effect itself, improving the dynamic control performance of the fusion power system. The specific technical solution is as follows:

[0005] A Hall current sensor based on tunnel magnetoresistive composite correction includes:

[0006] A ring-shaped support structure, which is used to be fitted around the conductor with a circular cross-section to be measured;

[0007] Multiple TMR sensors are mounted on the annular support structure and symmetrically distributed around the conductor;

[0008] At least one current Hall sensor is located in an adjacent plane;

[0009] The TMR sensor includes a high permeability magnetic shunt and a tunneling magnetoresistive (TMR) sensor, with the high permeability magnetic shunt adjacent to the TMR sensor.

[0010] A differential detection circuit is used to perform differential processing on the output signal of the TMR sensor located at a symmetrical position to obtain a differential output signal;

[0011] And a data processing unit, which is electrically connected to the TMR sensor and the current Hall sensor.

[0012] The present invention has the following beneficial effects:

[0013] High-precision and low-phase-delay control of current in the power supply of nuclear fusion devices (such as tokamaks) is crucial for accurately controlling plasma equilibrium and configuration, and current detection is a prerequisite for current control. In strong magnetic field and high-current environments, Hall current sensors, with their electrical isolation, wide measurement range, and anti-interference capabilities, as well as their progressive degradation characteristics (performance decreases slowly, continuously, and predictably over time), remain a reliable choice for current measurement in nuclear fusion device power supplies. However, Hall sensors suffer from inherent physical delays due to the limited migration speed of charge carriers in semiconductors, leading to a vicious cycle of "delay-deviation amplification" in the power supply closed-loop control—a performance drawback of Hall sensors. Other sensors, such as Rogowski coil current sensors and magneto-optical current sensors, are ill-suited to handle the complex operating conditions of nuclear fusion devices and ensure system safety and reliability. Therefore, despite these performance limitations, Hall sensors remain the mainstream choice for current measurement in the power supply systems of nuclear fusion devices.

[0014] The present invention employs a Hall current sensor based on tunnel magnetoresistive composite correction, which can significantly reduce the influence of Hall sensor sampling phase delay and reduce magnetic field deviation caused by positional deviation during Hall installation, thereby greatly improving the performance of Hall sensor and enhancing the accuracy of power control in nuclear fusion devices.

[0015] An innovative composite layout structure is adopted, in which the tunnel magnetoresistive and Hall sensor are arranged in adjacent planes. Without affecting the sampling of the Hall sensor, the extremely low inertial delay (femtosecond level) of the tunnel magnetoresistive in the adjacent plane is used to accurately capture transient changes in current and detect weak changes in magnetic field, providing a phase correction time reference for the inherent phase delay of the Hall sensor.

[0016] Since the tunnel magnetoresistive field itself cannot meet the requirements for degraded operation after a single-point failure of the current detection in nuclear fusion engineering, an innovative magnetic shunt design is used to utilize the sensitivity coefficient of the tunnel magnetoresistive field relative to the current Hall effect. This design attenuates the strong magnetic field according to a specific ratio, ensuring that the tunnel magnetoresistive sensitive element operates within the linear range.

[0017] In strong magnetic field environments, misalignment of the installation position of high-current Hall elements can lead to a deterioration in the linearity of Hall output. The innovative use of a tunnel magnetoresistive ring structure and a cross-shaped symmetrical layout for differential measurement ensures that the magnetic field changes detected by the symmetrical tunnel magnetoresistive elements are equal in magnitude but opposite in direction. The differential output cancels out the influence of the deviation, thereby providing installation deviation compensation for Hall detection and improving detection accuracy. Attached Figure Description

[0018] Figure 1 This is a flowchart of the structural design and signal processing of the present invention;

[0019] Figure 2 This is the TMR differential output circuit diagram. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0021] like Figure 1As shown, this invention provides a Hall current sensor based on tunnel magnetoresistive composite correction, comprising: a ring support structure for mounting around a conductor with a circular cross-section to be measured; multiple TMR sensors mounted on the ring support structure and symmetrically distributed around the conductor, preferably four in a cross-shaped symmetrical arrangement; at least one current Hall sensor located in an adjacent plane; the TMR sensor includes a high permeability magnetic shunt and a tunnel magnetoresistive TMR, the high permeability magnetic shunt being adjacent to the tunnel magnetoresistive TMR and used to guide most of the magnetic field generated by the conductor to flow along the high permeability magnetic shunt, allowing only a portion of the magnetic field to act on the tunnel magnetoresistive TMR, thereby weakening the magnetic field strength flowing through the tunnel magnetoresistive TMR and preventing magnetic saturation of the tunnel magnetoresistive TMR; a differential detection circuit for differentially processing the output signal of the TMR sensor located in symmetrical positions to obtain a differential signal that reflects the magnetic field of the measured current and suppresses common-mode interference; and a data processing unit electrically connected to the TMR sensor and the current Hall sensor.

[0022] The high-permeability magnetic shunt is made of a soft magnetic material with high permeability and moderate saturation flux density. It is arranged close to and parallel to the tunnel magnetoresistive (TMR), and its shape is adapted to the cross-section of the TMR. It is in contact with the magnetic core of the magnetic ring. When the magnetic field generated by the conductor current enters the high-permeability magnetic shunt, most of the magnetic field forms a closed magnetic circuit along the high-permeability magnetic shunt, and a small part of the magnetic field forms a closed magnetic circuit along the tunnel magnetoresistive (TMR). This limits the magnetic field strength of the tunnel magnetoresistive (TMR) to its linear operating range.

[0023] The differential detection circuit subtracts the outputs of a pair of symmetrically arranged TMR sensors in the vertical direction to obtain a first differential signal; and subtracts the outputs of a pair of symmetrically arranged TMR sensors in the horizontal direction to obtain a second differential signal. The first differential signal and the second differential signal are used together to calculate the magnetic field generated by the measured current and the conductor eccentricity deviation. The common-mode interference magnetic field is canceled in the differential operation, while the magnetic field signal of the measured current is enhanced in the differential result.

[0024] like Figure 1 As shown, the ring-shaped support structure uses a permanent magnet ring to construct a closed magnetic field loop, confining the magnetic field generated by the conductor current within the core of the permanent magnet ring to prevent magnetic field leakage. The radius of the magnetic field is determined accordingly. Below, the Hall element detects a magnetic field proportional to the current; the Hall element is located in the air gap of the magnetic core, and the subsequent stage is connected to the output sampling circuit. The magnetic field strength B within the magnetic ring is formed by the conduction current; the radius of the magnetic field is... .

[0025] The plane of the permanent magnet ring where the tunnel magnetoresistive resistor (TMR) is located is perpendicular to the conductor, and the axis of the permanent magnet ring coincides with the conductor. Four tunnel magnetoresistive resistors (TMR1-4) are set up, located at the left and right ends and the top and bottom vertices of the permanent magnet ring, respectively, in a cross-shaped symmetrical arrangement.

[0026] The high permeability magnetic shunt is located on both sides of the tunnel magnetoresistive (TMR), placed in parallel, and its top is connected to the magnetic core of the permanent magnet ring. It uses the high permeability to absorb the magnetic field and separate the magnetic field from the TMR. The whole is embedded in the ferrite substrate to form a closed magnetic circuit.

[0027] A permalloy magnetic bridge is used for magnetic shunting in the high-permeability magnetic circuit. The permalloy magnetic bridge is located on both sides of the tunnel magnetoresistive (TMR). According to Ohm's law of magnetism, the magnetic flux flowing through the permalloy magnetic bridge and the TMR is inversely proportional to their respective magnetic reluctances. Therefore, by selecting a low-resistance permalloy magnetic bridge to shun the magnetic field in the permanent magnet ring, the strong magnetic field is attenuated to a specific ratio before flowing through the TMR, thus allowing the TMR to operate in a strong magnetic field environment and achieve linear output. In the magnetic shunting design, to improve measurement accuracy, the Crocus CT100 TMR model is selected, with a linear error of <0.5% within ±20mT. The magnetic shunting ratio between the TMR and the permalloy magnetic bridge is set to 1:99.

[0028] According to Ohm's law of magnetism: , It is a magnetomotive force. For magnetic reluctance, For magnetic flux, the magnetomotive force of parallel branches is equal ( , The magnetomotive force of a high-permeability magnetic shunt permalloy magnetic bridge is... (This refers to the tunnel magnetoresistance (TMR) magnetomotive force), therefore... , For high-permeability magnetic shunts, the permalloy magnetic bridge flux is used. For tunnel magnetoresistive (TMR) flux, For high permeability magnetic shunt permalloy magnetic bridge reluctance, The TMR (tunnel magnetoresistance) is calculated using the following formula: ,in The length of the magnetic circuit. Permeability, For the cross-sectional area, the ratio of the tunnel magnetoresistive TMR to the permalloy magnetic bridge is set to 1:99. , The length of the TMR magnetic circuit is given. The permeability of the tunnel magnetoresistance (TMR). The cross-sectional area of ​​the tunnel magnetoresistive (TMR) is given. The length of the permalloy magnetic bridge magnetic circuit. The permeability of the permalloy magnetic bridge. The cross-sectional area of ​​the permalloy magnetic bridge is given; the magnetic bridge is selected from permalloy (Ni-Fe alloy 1J85). TMR paired with a ceramic substrate, According to the relationship between magnetic flux and magnetic field The magnetic field is diverted to the tunnel magnetoresistive (TMR) region. , This refers to the magnetic field at the tunnel magnetoresistance (TMR). Design the total magnetic field inside the permanent magnet ring. (Corresponding to a maximum current of 100kA), T stands for Tesla, which is the unit of magnetic flux density. It meets the linear operating range (±20mT) of Crocus CT100 and has no risk of saturation.

[0029] like Figure 2 As shown, the differential output circuit utilizes a symmetrically matched TMR sensor for output, suppressing synchronous changes caused by temperature, installation deviations, etc., and extracting the differential mode signal to reflect changes in the magnetic field. The TMR sensor adopts an open-loop structure to directly output the resistance signal, reducing response delay, avoiding high-frequency loop oscillation, and reducing system power consumption. TMR1 and TMR3 are symmetrical in the vertical direction, and their output voltages are respectively... , TMR2 and TMR4 are symmetrical in the horizontal direction. Let their output voltages be respectively... , In the circuit , , , , , All are sampling resistors, differential output. satisfy: Differential output satisfy: The tunnel magnetoresistance (TMR) characteristics are consistent, that is... , Zero magnetic field output, For tunnel magnetoresistive (TMR) sensitivity, It is a magnetic field. , , , These are the magnetic fields of the tunnel magnetoresistance TMR1, TMR2, TMR3, and TMR4, respectively. When common-mode interference exists (such as temperature-induced interference),... Synchronous drift ),have: , , , Vertical tunnel magnetoresistive differential output That is, the common-mode interference ΔV0 is canceled out, and only the magnetic field differential-mode signal is retained. Horizontal tunnel magnetoresistive differential output That is, the common-mode interference ΔV0 is canceled out, and only the magnetic field differential-mode signal is retained. .

[0030] Take the distance between the tunnel magnetic resistance and the center of the conductor The conductor's center shifted due to installation misalignment. This makes the distance from the center of the conductor... The tunnel magnetoresistance magnetic field is The magnetic field at the symmetrical tunnel magnetoresistance is Reverse equal change The distance between the tunnel magnetoresistance and the center of the conductor Magnetic field at time The difference in magnetic field introduced by the installation position deviation.

[0031] There is a magnetic field difference when the current Hall effect is installed with a deviation compared to when there is no installation deviation. (During Hall installation deviation, the axis of the current conductor under test, the current Hall, and the magnetic ring containing the tunnel magnetoresistor do not coincide.) The tunnel magnetoresistor (TMR) and the Hall are installed on adjacent planes and are coaxial, with the same magnetic ring radius. The difference in the magnetic field of the tunnel magnetoresistor is... Difference between current and Hall magnetic field Proportional, with , ( (The spatial coupling coefficient, calibrated experimentally), when the conductor and the magnetic ring axis are not coincident, the tunnel magnetoresistive output voltage difference is [value missing]. The difference between the current and the Hall magnetic field was obtained. , For tunnel magnetoresistive (TMR) sensitivity; the actual Hall output needs to eliminate the influence of the bias magnetic field, and the corrected Hall output amplitude is as follows: , This is the actual output voltage of the Hall effect sensor. To adjust the Hall output amplitude for Hall sensitivity.

[0032] TMR is based on the tunneling magnetoresistance effect. Since electron tunneling is inertial, the tunneling magnetoresistance response can be considered an ideal, time-delay-free reference. It is calculated separately using signal processing circuits. and And calculate the phase difference value. This is the output voltage of the tunnel magnetoresistive (TMR) system. The output voltage of the Hall element is [value], and the phase difference between the two is [value]. Based on the relationship between the phase difference and time delay of a sinusoidal signal: Therefore: , The angular frequency of the current signal. The output time-domain correction model considering the Hall lag time is as follows: After phase and amplitude correction, the Hall theoretical output value is obtained as follows: .

Claims

1. A Hall current sensor based on tunnel magnetoresistive composite correction, characterized in that, include: A ring-shaped support structure, which is used to be fitted around the conductor with a circular cross-section to be measured; Multiple TMR sensors are mounted on the annular support structure and symmetrically distributed around the conductor; At least one current Hall sensor is located in an adjacent plane; The TMR sensor includes a high permeability magnetic shunt and a tunneling magnetoresistive (TMR) sensor, with the high permeability magnetic shunt adjacent to the TMR sensor. A differential detection circuit is used to perform differential processing on the output signal of the TMR sensor located at a symmetrical position to obtain a differential output signal; It also includes a data processing unit, which is electrically connected to the differential detection circuit to perform signal processing.

2. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The high permeability magnetic branch is made of soft magnetic material with high permeability and moderate saturation magnetic flux density. It is arranged close to the tunnel magnetoresistive rheostat (TMR) and parallel to the TMR. Its shape is adapted to the cross-section of the TMR and it is in contact with the magnetic core of the magnetic ring.

3. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The preferred number of TMR sensors is four, arranged in a cross-shaped symmetrical configuration.

4. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The ring-shaped support structure uses a permanent magnet ring.

5. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 4, characterized in that, include: The high permeability magnetic shunt is located on both sides of the tunnel magnetoresistive (TMR), placed in parallel and with its top end connected to the magnetic core of the permanent magnet ring. The high permeability magnetic shunt and the TMR separate the magnetic fields and are embedded in the ferrite substrate to form a closed magnetic circuit.

6. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The high permeability magnetic shunt uses a permalloy magnetic bridge.

7. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The tunnel magnetoresistive (TMR) model selected is Crocus CT100, which has a linearity error of <0.5% within a range of ±20mT, and the magnetic field splitting ratio is set to 100:

1.

8. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, include: The differential detection circuit subtracts the outputs of a pair of symmetrically arranged TMR sensors, TMR1 and TMR3, located in the vertical direction to obtain the first differential signal. The second differential signal is obtained by subtracting the outputs of a pair of symmetrically arranged TMR sensors, TMR2 and TMR4, located in the horizontal direction. The first differential signal and the second differential signal are used to calculate the magnetic field generated by the measured current and the conductor eccentricity deviation.

9. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 1, characterized in that, Vertical differential output signal ,in, For tunnel magnetoresistive (TMR) sensitivity, , These are the magnetic fields of the tunnel magnetoresistive TMR1 and TMR3, respectively; the horizontal differential output signal. , , The magnetic fields of the tunnel magnetoresistive TMR2 and TMR4 are respectively used. The differential output of the tunnel magnetoresistive force due to the installation offset is calculated by vector summation of the horizontal and vertical double differences. .

10. A Hall current sensor based on tunnel magnetoresistive composite correction according to claim 9, characterized in that, The output of the current Hall sensor after delay correction is: ； in, This is the actual output value of the Hall effect sensor. Hall sensitivity, For tunnel magnetoresistive (TMR) sensitivity, The Hall lag time, This is a tunnel magnetoresistive differential output. is the spatial coupling coefficient.

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