Alternating current / direct current multi-air-gap magnetoresistive current sensor and current measurement method

Abstract

The present invention provides an alternating current / direct current multi-air-gap magnetoresistive current sensor and a current measurement method. The alternating current / direct current multi-air-gap magnetoresistive current sensor comprises: a magnetic-to-electric conversion unit used for acquiring a magnetic field signal of a target current-carrying wire to which a current to be measured is introduced, converting the magnetic field signal into an electric signal and then outputting the electric signal to a signal processing unit, wherein the magnetic-to-electric conversion unit uses a multi-air-gap band-based closed-loop iron core type structure; the signal processing unit used for amplifying the electric signal and then outputting the electric signal to a feedback compensation unit; and the feedback compensation unit used for adjusting a feedback current on the basis of the amplified voltage signal to enable a novel magnetoresistive element to always work at zero magnetic flux, measuring the value of the feedback current, on the basis of the value of the feedback current, obtaining the value of the current to be measured, and outputting the value of the current to be measured. According to the alternating current / direct current multi-air-gap magnetoresistive current sensor and the current measurement method provided by the embodiments of the present invention, the measurement performance of the current sensor is improved and the problem of the difficulty in achieving both high accuracy and a wide frequency domain of alternating current / direct current measurement is solved.

Description

AC / DC multi-air-gap magnetoresistive current sensor and current measurement method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present invention claims priority to Chinese patent application No. 202310762174.0 filed with the Patent Office of China on June 26, 2023, entitled “AC / DC MULTI-AIR-GAP MAGNETORESISTANCE CURRENT SENSOR AND CURRENT MEASUREMENT METHOD”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of electrical measurement technology, and in particular to an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method. Background Art

[0004] New power systems feature a high proportion of renewable energy and power electronic equipment. High voltage and large currents contain complex components such as power frequency, harmonics, and DC, exhibiting wide dynamic, highly random, and time-varying characteristics. However, existing mainstream current sensors struggle to simultaneously address the accuracy and wide dynamic characteristics of current signals in complex environments. The mainstream current measurement device on the neutral line of a high-voltage direct current transmission system is a zero-flux DC current transformer, which has difficulty measuring high-frequency harmonics and suffers from poor insulation performance. Hall effect current sensors are often used for photovoltaic grid access, but they have limited accuracy and are susceptible to environmental interference such as temperature. In recent years, new, highly sensitive magnetoresistive sensing technologies have gradually gained application, but they suffer from poor anti-interference capabilities, conductor eccentricity errors, and frequency response consistency. Furthermore, they are affected by the hysteresis effect of the iron core, resulting in limited linear range and accuracy.

[0005] Summary of the Invention

[0006] In view of this, the present invention proposes an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method, aiming to solve the problems of poor anti-interference ability, conductor eccentricity error, frequency response consistency, and iron core hysteresis effect of existing sensing technologies.

[0007] In the first aspect, an embodiment of the present invention provides an AC / DC multi-air-gap magnetoresistive current sensor, which includes: a magnetoelectric conversion unit for obtaining a magnetic field signal of a target current-carrying conductor carrying a current to be measured, and converting the magnetic field signal into an electrical signal and outputting it to a signal processing unit, wherein the magnetoelectric conversion unit includes an iron core and N new magnetoresistive elements connected in parallel, N air gap openings are symmetrically arranged on the iron core, and the N new magnetoresistive elements are respectively located at the centers of the N air gap openings, N ≥ 3 and N is a positive integer; a signal processing unit for amplifying the electrical signal output by the magnetoelectric conversion unit and outputting it to a feedback compensation unit; a feedback compensation unit for adjusting the feedback current according to the amplified voltage signal output by the signal processing unit so that the new magnetoresistive element always operates at zero magnetic flux, measuring the feedback current value, and obtaining and outputting the current value to be measured according to the feedback current value.

[0008] Furthermore, the iron core is a circular magnetic ring and is evenly wound with a feedback winding. The magneto-electric conversion unit also includes a power supply circuit, which is used to be connected to the N new magnetoresistive elements for power supply. When the target current-carrying conductor carrying the current to be measured is placed at the center of the iron core, the N new magnetoresistive elements are used to obtain the magnetic field signal of the target current-carrying conductor carrying the current to be measured, and convert the magnetic field signal into an electrical signal and output it to the signal processing unit.

[0009] Furthermore, N new magnetoresistive elements are used to obtain the magnetic field signal of the target current-carrying wire with the current to be measured, and convert the magnetic field signal into an electrical signal and output it to the signal processing unit, including: using the following formula to obtain the input voltage V of each new magnetoresistive element i : V i =K i I i (B in -B c );

[0010] Among them, K i is the sensitivity of the i-th new magnetoresistive element, I i is the control current of the i-th new magnetoresistive element, B in and B c The compensation magnetic fields are generated by the original magnetic field and feedback current on the primary side respectively; based on the input voltage of each new magnetoresistive element, the equivalent circuit of the parallel capacitor is synthesized to obtain the combined voltage of N new magnetoresistive elements, and the combined voltage is output to the signal processing unit.

[0011] Furthermore, the novel magnetoresistive element is a tunneling magnetoresistive element.

[0012] Furthermore, the signal processing unit includes: a detection circuit, including a three-op-amp instrumentation amplifier, which is used to amplify the voltage signal output by the magnetoelectric conversion unit and output it to the feedback compensation unit; an interference suppression circuit, which is used for the component performance error correction circuit and the filtering circuit, wherein the component performance error correction circuit is used to generate an adjustment current according to the voltage signal output by the magnetoelectric conversion unit, and the filtering circuit is used to filter the high-frequency magnetic field signal coupled by the new magnetoresistive element to ensure low-pass characteristics; a multi-band feedback circuit, including several dynamic output feedback control circuits with limited frequency bands, which are used to ensure that the transmission characteristics of different frequencies are consistent.

[0013] Furthermore, the feedback compensation unit includes: a feedback winding, evenly wound on the iron core, for allowing feedback current to pass through; a driving circuit, for adjusting the feedback current output to the feedback winding according to the amplified voltage signal output by the signal processing unit, so that the compensation magnetic field is the same magnitude as the primary magnetic field and has an opposite direction; an output circuit, for measuring the feedback current value, and obtaining and outputting the current value to be measured according to the feedback current value.

[0014] Further, obtaining the current value to be measured according to the feedback current value includes: dividing the feedback current value by the coil turns ratio to obtain the current value to be measured.

[0015] Furthermore, the AC / DC multi-air-gap magnetoresistive current sensor further includes an annular housing for carrying an iron core wound with a feedback winding and N new magnetoresistive elements connected in parallel.

[0016] Furthermore, the annular housing uses an insulating layer to achieve voltage insulation.

[0017] In a second aspect, an embodiment of the present invention further provides a current measurement method, which uses the AC / DC multi-gap magnetoresistive current sensor provided by each of the above embodiments to measure the current to be measured of the target current-carrying conductor, obtain and output the current value to be measured; wherein, the target current-carrying conductor is at the center of the iron core of the AC / DC multi-gap magnetoresistive current sensor.

[0018] The embodiments of the present invention provide an AC / DC multi-gap magnetoresistive current sensor and a current measurement method. The AC / DC multi-gap magnetoresistive current sensor adopts a multi-gap frequency-band closed-loop iron core structure, which improves the measurement performance of the current sensor, overcomes the difficulty of balancing high accuracy and wide frequency domain in AC / DC current measurement, provides technical guidance for the development and application of high-voltage and high-current measurement equipment, and promotes the technical upgrading of high-voltage and high-current measurement equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 shows a schematic structural diagram of an AC / DC multi-air-gap magnetoresistive current sensor according to an embodiment of the present invention;

[0020] FIG2 shows a schematic structural diagram of a housing of an AC / DC multi-air-gap magnetoresistive current sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0022] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0023] FIG1 shows a schematic structural diagram of an AC / DC multi-air-gap magnetoresistive current sensor according to an embodiment of the present invention.

[0024] As shown in FIG1 , the AC / DC multi-air-gap magnetoresistive current sensor includes:

[0025] The magnetoelectric conversion unit 100 is used to obtain the magnetic field signal of the target current-carrying conductor 400 through which the current to be measured flows, and convert the magnetic field signal into an electrical signal and output it to the signal processing unit 200, wherein the magnetoelectric conversion unit 100 includes an iron core 101 and N parallel new magnetoresistive elements 102, N air gap openings 104 are symmetrically arranged on the iron core 101, and the N new magnetoresistive elements 102 are respectively located at the center of the N air gap openings 104, N ≥ 3 and N is a positive integer.

[0026] Furthermore, the iron core 101 is a circular magnetic concentrator ring and is evenly wound with the feedback winding 301. The magnetoelectric conversion unit further includes a power supply circuit 103 for connecting to the N novel magnetoresistive elements 102 for power supply.

[0027] When the target current-carrying conductor 400 carrying the current to be measured is placed at the center of the iron core 101, the N new magnetoresistive elements 102 are used to obtain the magnetic field signal of the target current-carrying conductor 400 carrying the current to be measured, and convert the magnetic field signal into an electrical signal and output it to the signal processing unit 200.

[0028] The above embodiment adopts a multi-air-gap frequency-band closed-loop iron core structure, that is, the high interference sensitivity of the ring array current sensor is avoided by the magnetic concentration effect of the iron core, the wire eccentricity and non-uniform winding error of the single-air-gap iron core structure are avoided by multiple air gaps, and the iron core hysteresis effect is avoided by the zero magnetic flux closed-loop structure.

[0029] Furthermore, N novel magnetoresistive elements are used to obtain magnetic field signals of a target current-carrying conductor through which the current to be measured flows, and convert the magnetic field signals into electrical signals and output them to a signal processing unit, including:

[0030] The input voltage V of each new magnetoresistive element is obtained using the following formula (1): i : V i =K i I i (B in -B c ) (1)

[0031] Among them, K i is the sensitivity of the i-th new magnetoresistive element, I i is the control current of the i-th new magnetoresistive element, B in and B c are the compensation magnetic fields generated by the original magnetic field on the primary side and the feedback current respectively;

[0032] Based on the input voltage of each new magnetoresistive element, the combined voltage of N new magnetoresistive elements is obtained by synthesizing the equivalent circuit of the parallel capacitor, and the combined voltage is output to the signal processing unit.

[0033] Furthermore, the novel magnetoresistive element is a tunneling magnetoresistive (TMR) element.

[0034] The above embodiments use new magnetoresistive elements such as TMR, which have advantages such as high sensitivity and wide frequency response range.

[0035] The signal processing unit 200 is used to amplify the electrical signal output by the magnetoelectric conversion unit 100 and output it to the feedback compensation unit 300 .

[0036] Furthermore, the signal processing unit 200 includes:

[0037] The detection circuit 201 includes a three-op-amp instrumentation amplifier, which is used to amplify the voltage signal output by the magnetoelectric conversion unit and output it to the feedback compensation unit;

[0038] Interference suppression circuit 202, used for component performance error correction circuit and filter circuit, wherein the component performance error correction circuit is used to generate a regulating current according to the voltage signal output by the magnetoelectric conversion unit, and the filter circuit is used to filter the high-frequency magnetic field signal coupled by the novel magnetoresistive element to ensure low-pass characteristics;

[0039] The multi-band feedback circuit 203 includes several dynamic output feedback control circuits with limited frequency bands, and is used to ensure that the transmission characteristics of different frequencies are consistent.

[0040] The detection circuit is used to amplify the weak output voltage of the TMR element with a small amplitude for calculation and filtering. It is mainly composed of a three-op-amp instrumentation amplifier. Its REF pin is grounded to maintain a very low source impedance. A zero adjustment circuit is designed in the detection circuit. A precision adjustable resistor is connected in series between two equal-value resistors. A precision operational amplifier is used to form a voltage follower as a buffer. The positive input of the precision operational amplifier is connected to the middle pin of the precision adjustable resistor, and its output is used as the zero adjustment voltage output.

[0041] The interference suppression circuit includes component performance error correction and filtering circuits. The component performance error correction and compensation method based on the signal injection method uses a decomposition unit to identify the excitation signal from the current detected by the TMR element based on the specific waveform characteristics. This is used to calculate the overall gain of the magnetic sensor measurement circuit and determine the change in the measurement characteristics of the magnetic resistor chip, thereby generating a regulating current. The filtering circuit is used to filter out any high-frequency magnetic field signals that may be coupled to ensure low-pass characteristics. The filtering circuit uses a second-order Butterworth low-pass filter built with a precision operational amplifier.

[0042] The multi-band feedback circuit is designed based on the frequency-band feedback mechanism to determine the difference in the response of current signals in different frequency ranges from low frequency to high frequency in the sensor circuit. Multiple dynamic output feedback control circuits with limited frequency bands are designed for different frequency domains to ensure that the transmission characteristics of different frequencies are consistent.

[0043] The above embodiment adopts a multi-physical field interference suppression method, corrects zero drift through a detection circuit containing zero drift correction, corrects component performance errors through a component error correction and compensation circuit module based on a signal injection method, and filters possible coupled electromagnetic field interference signals through an electromagnetic field interference filter; and adopts a frequency band feedback mechanism to ensure the consistency of transmission characteristics of different frequencies.

[0044] The feedback compensation unit 300 is used to adjust the feedback current according to the amplified voltage signal output by the signal processing unit 200 so that the new magnetoresistive element always operates at zero flux, measure the feedback current value, and obtain and output the current value to be measured based on the feedback current value.

[0045] Furthermore, the feedback compensation unit 300 includes:

[0046] The feedback winding 301 is evenly wound around the iron core and is used to pass the feedback current;

[0047] The driving circuit 302 is configured to adjust the feedback current output to the feedback winding according to the amplified voltage signal output by the signal processing unit, so that the compensation magnetic field has the same magnitude as the primary magnetic field and has an opposite direction;

[0048] The output circuit 303 is used to measure the feedback current value, and obtain and output the current value to be measured according to the feedback current value.

[0049] Furthermore, the current value to be measured is obtained according to the feedback current value, including:

[0050] Divide the feedback current value by the coil turns ratio to obtain the current value to be measured.

[0051] The amplified output voltage drives the push-pull transistor to adjust the feedback current I output to the compensation coil wound on the iron core. c , so that the compensation magnetic field is the same size as the primary magnetic field and opposite in direction, so that the TMR element always works near zero magnetic flux, at this time I c With the primary current I in The ratio is the ratio of the number of coil turns. Then, by measuring the resistance, the feedback current I is measured. c As the voltage on the in At this time, the actual magnetic field on the sensor is the difference between the external magnetic field and the feedback magnetic field. The sensor actually works in a very small magnetic field range.

[0052] Furthermore, the AC / DC multi-air-gap magnetoresistive current sensor also includes an annular housing for carrying an iron core wound with a feedback winding and N new magnetoresistive elements connected in parallel. The annular housing uses a special process annular insulation layer to achieve voltage insulation.

[0053] Furthermore, the annular housing adopts an insulating layer to achieve voltage insulation.

[0054] Figure 2 shows a schematic diagram of the housing structure of an AC / DC multi-gap magnetoresistive current sensor according to an embodiment of the present invention. As shown in Figure 2, the annular housing, the iron core with the feedback winding, and N parallel-connected novel magnetoresistive elements contained within it form a sensing ring. A specially engineered annular insulation layer within the sensing ring provides voltage isolation, while the power supply and secondary circuit implement current sensing on the low-voltage side.

[0055] The ring-shaped housing ensures the insulation performance of the sensor.

[0056] The above embodiment provides an AC / DC multi-air-gap magnetoresistive current sensor, which adopts a multi-air-gap frequency-band closed-loop iron core structure, improves the measurement performance of the current sensor, overcomes the difficulty of balancing high accuracy and wide frequency domain in AC / DC current measurement, provides technical guidance for the development and application of high-voltage and high-current measurement equipment, and promotes the technological upgrading of high-voltage and high-current measurement equipment.

[0057] An embodiment of the present invention also provides a current measurement method, which uses the AC / DC multi-gap magnetoresistive current sensor provided by each of the above embodiments to measure the current to be measured of the target current-carrying conductor, obtain and output the current value to be measured; wherein, the target current-carrying conductor is located at the center of the iron core of the AC / DC multi-gap magnetoresistive current sensor.

[0058] The embodiments of the present invention design an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method, which can avoid the high interference sensitivity of a ring array current sensor, reduce the influence of errors such as wire eccentricity and external interference, avoid the hysteresis effect of the iron core, and overcome the difficult problem of balancing high accuracy and wide frequency domain in high-voltage and large-current DC measurement.

[0059] The AC / DC multi-air-gap magnetoresistive current sensor mainly includes a magnetoelectric conversion part, a signal processing part and a feedback compensation part.

[0060] The magnetoelectric conversion section consists of an iron core, four TMR elements, and a power supply circuit. The iron core is circular with a square cross-section and made of an iron-based nanocrystalline alloy or Permalloy. The feedback winding is evenly wound around the core, and four air gaps are symmetrically distributed on the core.

[0061] The four TMR elements of the magnetoelectric conversion part are installed in the center of the four air gaps of the iron core. When the iron core is placed on a current-carrying conductor with the current to be measured I_in, the calculation formula for the input voltage of each TMR element can refer to the above formula (1).

[0062] Since the current-carrying conductor is not necessarily at the center of the core, the primary magnetic field induced by the primary current in the air gap is different. Let the total magnetic field formed by the primary magnetic field and the feedback magnetic field in the air gap at the i-th TMR element be B i After the circuits are connected in parallel and synthesized according to the equivalent circuit of parallel capacitors, the combined output voltage of the four TMR elements is:

[0063] The combined output voltage of the TMR elements is input to the signal processing section.

[0064] The power supply circuit of the magnetoelectric conversion part uses an LDO chip as the power supply for the TMR element and a small 2.2μF ceramic output capacitor to maintain the stability of the fixed output voltage to power the four TMR elements. A temperature drift error correction and compensation circuit based on thermistors is designed, and a common-mode proportional amplifier circuit is built using a negative temperature coefficient thermistor to adjust the supply voltage of the TMR sensor chip when the temperature changes.

[0065] The signal processing section consists of a detection circuit, an interference suppression circuit, and a multi-band feedback circuit. The detection circuit amplifies the weak, small-amplitude output voltage of the TMR element for computation and filtering. It primarily consists of a three-op-amp instrumentation amplifier, with its REF pin grounded to maintain a very low source impedance. A zero-adjustment circuit is designed within the detection circuit, connecting a precision adjustable resistor in series between two equal-value resistors. A precision operational amplifier forms a voltage follower as a buffer. The positive input of the precision operational amplifier is connected to the middle pin of the precision adjustable resistor, and its output serves as the zero-adjustment voltage.

[0066] The interference suppression circuitry in the signal processing section includes component performance error correction and filtering circuits. The component performance error correction and compensation method, based on the signal injection method, uses a decomposition unit to identify the excitation signal from the current detected by the TMR element based on its specific waveform characteristics. This is used to calculate the overall gain of the magnetic sensor measurement circuit, determine changes in the measurement characteristics of the magnetoresistive resistor chip, and thus generate a regulating current. The filtering circuit is used to filter out any high-frequency magnetic field signals that may be coupled to ensure low-pass characteristics. The filtering circuit uses a second-order Butterworth low-pass filter built with a precision operational amplifier.

[0067] The multi-band feedback circuit of the signal processing part is designed according to the frequency-band feedback mechanism. Based on the difference in the response of current signals of different frequencies in the sensor circuit, the optimization goal is to ensure the consistency of the transmission characteristics of different frequencies from low-frequency to high-frequency signals, and design multiple dynamic output feedback control circuits with limited frequency bands.

[0068] The feedback compensation part consists of the drive circuit, feedback winding and output resistor. The amplified output voltage drives the push-pull transistor, and the transistor outputs the feedback current I c To the compensation coil. When the measurement range is not exceeded, the magnetic field generated by the output current of the operational amplifier and transistor working in the linear region is the same in magnitude and opposite in direction to the measured magnetic field. The feedback winding receives the output of the transistor, which makes B c is the magnetic field induced by the feedback current:

[0069] Among them I c is the feedback current, N2 is the number of turns of the compensation coil. When the compensation magnetic field and the original magnetic field cancel each other out and reach zero magnetic flux, that is:

[0070] At this time, N2I c =I in , that is I c With the primary current I in The ratio is the ratio of the number of coil turns. Then the feedback current I is measured by Ohm's law. c , we get the determination I inAt this time, the actual magnetic field on the sensor is the difference between the external magnetic field and the feedback magnetic field. The sensor actually works in a very small magnetic field range.

[0071] The external structure design of the current sensor is as follows: based on the above-mentioned high-voltage DC quantum tunneling magnetoresistive current sensing method, the magnetoelectric conversion part is designed as a sensing ring. The voltage insulation is achieved inside the sensing ring through a special process annular insulation layer, and the power supply and secondary circuit realize current sensing on the low-voltage side.

[0072] The present invention designs an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method, which include the following technical solutions:

[0073] (1) Multi-gap frequency-band closed-loop iron core structure: The high interference sensitivity of the ring array current sensor is avoided by the iron core magnetic concentration effect, the conductor eccentricity and non-uniform winding error of the single air gap iron core structure are avoided by multiple air gaps, and the iron core hysteresis effect is avoided by the zero magnetic flux closed-loop structure;

[0074] (2) Multi-physics interference suppression method: The temperature drift error is corrected by the power supply with a temperature drift error correction and compensation circuit, the zero drift is corrected by the detection circuit with a zero drift correction, the component performance error is corrected by the component error correction and compensation circuit module based on the signal injection method, and the electromagnetic interference signal that may be coupled is filtered by the electromagnetic interference filter;

[0075] (3) Frequency band feedback mechanism: ensures the consistency of transmission characteristics at different frequencies;

[0076] (4) External structure design with an annular insulation layer: ensures the insulation performance of the sensor.

[0077] Through the above technical solutions, the measurement performance of quantum tunneling magnetoresistive current sensors can be improved, and the difficulty of balancing high accuracy and wide frequency domain in AC and DC current measurement can be overcome. This will provide technical guidance for the development and application of high-voltage and high-current measurement equipment and promote the technological upgrading of high-voltage and high-current measurement equipment.

[0078] The present invention provides an AC / DC multi-air-gap magnetoresistive current sensor, which mainly comprises a magnetoelectric conversion part, a signal processing part and a feedback compensation part.

[0079] The magnetoelectric conversion section consists of an iron core, a power supply circuit, and four TMR elements. The iron core is circular with a square cross-section and made of an iron-based nanocrystalline alloy or Permalloy. The feedback winding is evenly wound around the core, and four air gaps are symmetrically distributed throughout the core. The four TMR elements are mounted at the center of each of the four air gaps. The combined output voltage of the TMR elements is fed into the signal processing section.

[0080] The power supply circuit of the magnetoelectric conversion part uses an LDO chip as the power supply for the TMR element and a small 2.2μF ceramic output capacitor to maintain the stability of the fixed output voltage to power the four TMR elements. A temperature drift error correction and compensation circuit based on thermistors is designed, and a common-mode proportional amplifier circuit is built using a negative temperature coefficient thermistor to adjust the supply voltage of the TMR sensor chip when the temperature changes.

[0081] The signal processing section consists of a detection circuit, an interference suppression circuit, and a multi-band feedback circuit. The detection circuit amplifies the weak, small-amplitude output voltage of the TMR element for computation and filtering. It primarily consists of a three-op-amp instrumentation amplifier, with its REF pin grounded to maintain a very low source impedance. A zero-adjustment circuit is designed within the detection circuit, connecting a precision adjustable resistor in series between two equal-value resistors. A precision operational amplifier forms a voltage follower as a buffer. The positive input of the precision operational amplifier is connected to the middle pin of the precision adjustable resistor, and its output serves as the zero-adjustment voltage.

[0082] The interference suppression circuit includes component performance error correction and filtering circuits. The component performance error correction and compensation method based on the signal injection method uses a decomposition unit to identify the excitation signal from the current detected by the TMR element based on the specific waveform characteristics. This is used to calculate the overall gain of the magnetic sensor measurement circuit and determine the change in the measurement characteristics of the magnetic resistor chip, thereby generating a regulating current. The filtering circuit is used to filter out any high-frequency magnetic field signals that may be coupled to ensure low-pass characteristics. The filtering circuit uses a second-order Butterworth low-pass filter built with a precision operational amplifier.

[0083] The multi-band feedback circuit is designed according to the frequency-band feedback mechanism. Based on the difference in the response of current signals of different frequencies in the sensor circuit, the dynamic output feedback control circuits of multiple limited frequency bands are designed with the optimization goal of ensuring the consistency of the transmission characteristics of different frequencies from low-frequency to high-frequency signals.

[0084] The feedback compensation circuit consists of a drive circuit, feedback winding, and output resistor. The amplified output voltage drives the push-pull transistor, which then outputs feedback current I_c to the compensation coil. The actual magnetic field on the sensor is the difference between the external magnetic field and the feedback magnetic field. The feedback current is measured using Ohm's law, and the measured current can be obtained by calculating the compensation coil ratio.

[0085] The external structure design of the current sensor is as follows: based on the above-mentioned high-voltage DC quantum tunneling magnetoresistive current sensing method, the magnetoelectric conversion part is designed as a sensing ring. The voltage insulation is achieved inside the sensing ring through a special process annular insulation layer, and the power supply and secondary circuit realize current sensing on the low-voltage side.

[0086] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0087] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / the [means, component, etc.]" are to be interpreted openly as referring to at least one instance of the means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily need to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0088] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0090] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention. Industrial Applicability

[0093] In an embodiment of the present invention, a magnetoelectric conversion unit is used to obtain a magnetic field signal from a target current-carrying conductor carrying a current to be measured, convert the magnetic field signal into an electrical signal, and then output it to a signal processing unit. The magnetoelectric conversion unit adopts a multi-gap frequency-band closed-loop iron core structure. The signal processing unit is used to amplify the electrical signal and then output it to a feedback compensation unit. The feedback compensation unit is used to adjust the feedback current based on the amplified voltage signal so that the new magnetoresistive element always operates at zero magnetic flux, measure the feedback current value, and obtain and output the current value to be measured based on the feedback current value. In this way, the AC / DC multi-gap magnetoresistive current sensor adopts a multi-gap frequency-band closed-loop iron core structure, improves the current sensor measurement performance, overcomes the difficulty of balancing high accuracy and wide frequency domain in AC / DC current measurement, provides technical guidance for the development and application of high-voltage and high-current measurement equipment, and promotes the technological upgrading of high-voltage and high-current measurement equipment.

Claims

1. An AC / DC multi-air-gap magnetoresistive current sensor, the AC / DC multi-air-gap magnetoresistive current sensor comprising: A magnetoelectric conversion unit, used for acquiring a magnetic field signal of a target current-carrying conductor through which a current to be measured flows, and converting the magnetic field signal into an electrical signal and outputting it to a signal processing unit, wherein the magnetoelectric conversion unit comprises an iron core and N new magnetoresistive elements connected in parallel, N air gap openings are symmetrically arranged on the iron core, and the N new magnetoresistive elements are respectively located at the centers of the N air gap openings, where N ≥ 3 and N is a positive integer; A signal processing unit, used to amplify the electrical signal output by the magnetoelectric conversion unit and output it to the feedback compensation unit; The feedback compensation unit is used to adjust the feedback current according to the amplified voltage signal output by the signal processing unit so that the new magnetoresistive element always operates at zero flux, measure the feedback current value, and obtain and output the current value to be measured according to the feedback current value.

2. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 1, wherein: The iron core is a circular magnetic concentrator ring and is evenly wound with a feedback winding. The magneto-electric conversion unit also includes a power supply circuit, which is used to be connected to the N novel magnetoresistive elements respectively for power supply; When the target current-carrying wire carrying the current to be measured is placed at the center of the iron core, N new magnetoresistive elements are used to obtain the magnetic field signal of the target current-carrying wire carrying the current to be measured, and convert the magnetic field signal into an electrical signal and output it to the signal processing unit.

3. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2, wherein: N novel magnetoresistive elements are used to obtain magnetic field signals of a target current-carrying wire through which a current to be measured flows, and convert the magnetic field signals into electrical signals and output them to a signal processing unit, including: The input voltage V of each new magnetoresistive element is obtained using the following formula: i : V i =K i I i (B in -B c ); Among them, K i is the sensitivity of the i-th new magnetoresistive element, I i is the control current of the i-th new magnetoresistive element, B in and B c are the compensation magnetic fields generated by the original magnetic field on the primary side and the feedback current respectively; Based on the input voltage of each new magnetoresistive element, the equivalent circuit of the parallel capacitor is synthesized to obtain N The combined voltage of the novel magnetoresistive elements is output to a signal processing unit.

4. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2, wherein: The novel magnetoresistive element is a tunneling magnetoresistive element.

5. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2, wherein: The signal processing unit comprises: A detection circuit, including a three-op-amp instrumentation amplifier, for amplifying the voltage signal output by the magnetoelectric conversion unit and outputting it to a feedback compensation unit; An interference suppression circuit is used for a component performance error correction circuit and a filter circuit, wherein the component performance error correction circuit is used to generate a regulating current according to a voltage signal output by the magnetoelectric conversion unit, and the filter circuit is used to filter a high-frequency magnetic field signal coupled by the novel magnetoresistive element to ensure a low-pass characteristic; The multi-band feedback circuit includes a plurality of dynamic output feedback control circuits of limited frequency bands, and is used to ensure that the transmission characteristics of different frequencies are consistent.

6. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2, wherein: The feedback compensation unit comprises: The feedback winding is evenly wound on the iron core and is used to pass the feedback current; A driving circuit, used for adjusting the feedback current output to the feedback winding according to the amplified voltage signal output by the signal processing unit, so that the compensation magnetic field is the same in magnitude and opposite in direction to the primary magnetic field; The output circuit is used to measure the feedback current value, and obtain and output the current value to be measured according to the feedback current value.

7. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 6, wherein: According to the feedback current value, the current value to be measured is obtained, including: The feedback current value is divided by the coil turns ratio to obtain the current value to be measured.

8. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 6, wherein: The AC / DC multi-air-gap magnetoresistive current sensor further comprises an annular housing for carrying an iron core wound with a feedback winding and N new magnetoresistive elements connected in parallel.

9. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 8, wherein: The annular housing uses an insulating layer to achieve voltage insulation.

10. A current measurement method, using the AC / DC multi-air-gap magnetoresistive current sensor as claimed in any one of claims 1 to 9 to measure the current to be measured of the target current-carrying conductor, and obtain and output the current value to be measured; wherein, The target current-carrying conductor is located at the center of the core of the AC / DC multi-air-gap magnetoresistive current sensor.

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