AC / DC Multi-Air-Gap Magnetoresistive Current Sensor and Current Measurement Method

Abstract

The present invention provides an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method. The AC / DC multi-air-gap magnetoresistive current sensor is a magnetoelectric conversion unit configured to acquire a magnetic field signal of a target energized wire through which a current to be measured flows, convert the magnetic field signal into an electrical signal, and output the electrical signal to a signal processing unit. The magnetoelectric conversion unit adopts a multi-air-gap sub-band closed-loop core structure. A signal processing unit configured to perform amplification processing on the electrical signal and then output the electrical signal to a feedback compensation unit. A feedback compensation unit configured to adjust a feedback current based on the amplified voltage signal so that a new type of magnetoresistive element can always operate with zero magnetic flux, measure the feedback current value, obtain the current value to be measured based on the feedback current value, and output the current value to be measured.

Description

Technical Field

[0001] (Cross - reference to related applications) This invention claims the priority of a Chinese patent application with the application number 202310762174.0 and the invention title "AC - DC Multi - Air - Gap Magnetoresistive Current Sensor and Current Measurement Method", which was filed with the Chinese Patent Office on June 26, 2023, and all the contents of the Chinese patent application are incorporated into this invention by reference.

[0002] This invention relates to the field of electrical measurement technology, specifically to an AC - DC multi - air - gap magnetoresistive current sensor and a current measurement method.

Background Art

[0003] The new power system is equipped with a high proportion of renewable energy and a high proportion of power electronic equipment. High - voltage and large - current signals contain complex components such as commercial frequency, harmonics, and direct current, showing characteristics of wide dynamic range, strong randomness, and strong time - variability. However, existing mainstream current sensors have difficulty simultaneously meeting the measurement requirements of current signals in terms of accuracy, wide dynamic characteristics, etc. in a complex environment. The mainstream current measurement device for the neutral line of the high - voltage direct - current power transmission system is a zero - flux type direct - current converter, which is difficult to measure high - frequency harmonics and has poor insulation performance. Hall current sensors are often used to connect solar power generation to the power grid, but their accuracy is limited and they are easily affected by environmental interferences such as temperature. In recent years, new high - sensitivity magnetoresistive sensing technologies have been gradually applied, but there are problems such as low anti - interference ability, conductor eccentricity error, and consistency of frequency response. Also, due to the influence of the hysteresis effect of the iron core, the linear range and accuracy are limited.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In view of this, an object of the present invention is to solve problems such as low anti-interference ability, conductor eccentricity error, frequency response consistency, and influence of the hysteresis effect of the iron core in existing sensing technologies, and to propose an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method.

Means for Solving the Problems

[0005] According to a first aspect, an embodiment of the present invention provides an AC / DC multi-air-gap magnetoresistive current sensor. The AC / DC multi-air-gap magnetoresistive current sensor is a magnetoelectric conversion unit configured to acquire a magnetic field signal of a target energized wire through which a current to be measured flows, convert the magnetic field signal into an electrical signal, and then output it to a signal processing unit. It includes an iron core and N (N≥3 and N is a positive integer) new-type magnetoresistive elements connected in parallel. N air-gap openings are symmetrically provided in the iron core, and the N new-type magnetoresistive elements are respectively arranged at the centers of the N air-gap openings. It further includes a signal processing unit configured to perform amplification processing on the electrical signal output by the magnetoelectric conversion unit and then output it to a feedback compensation unit, and based on the amplified voltage signal output by the signal processing unit, adjust the feedback current so that the new-type magnetoresistive element can always operate with zero magnetic flux, measure the feedback current value, obtain the current value to be measured based on the feedback current value, and output the current value to be measured. It also includes a feedback compensation unit.

[0006] Furthermore, the iron core is a circular magnetic flux collecting ring, and a feedback winding is evenly wound. The magnetoelectric conversion unit further includes a power supply circuit used to supply power by connecting to each of the N new-type magnetoresistive elements. When the target energized wire through which the current to be measured flows is arranged at the center of the iron core, the N new-type magnetoresistive elements are used to acquire the magnetic field signal of the target energized wire through which the current to be measured flows, convert the magnetic field signal into an electrical signal, and then output it to the signal processing unit.

[0007] Furthermore, the N novel magnetoresistive elements acquire a magnetic field signal of a target current-carrying wire through which a current to be measured flows, convert the magnetic field signal into an electrical signal, and then output the signal to a signal processing unit. This includes: obtaining the input voltage V of each novel magnetoresistive element by the following formula: i where: [Number] K i is the sensitivity of the i-th novel magnetoresistive element, I i is the control current of the i-th novel magnetoresistive element, B in is the primary magnetic field, and B c is the compensation magnetic field generated by the feedback current. Based on the input voltage of each novel magnetoresistive element, the combined voltage of the N novel magnetoresistive elements is obtained by equivalent circuit synthesis of parallel capacitors, and the combined voltage is output to the signal processing unit.

[0008] Furthermore, the novel magnetoresistive element is a tunnel magnetoresistive element.

[0009] Furthermore, the signal processing unit includes a detection circuit with an instrumentation amplifier configured with three op-amps, which is configured to amplify the voltage signal output by the magnetoelectric conversion unit and then output it to a feedback compensation unit; an interference suppression circuit used for an element performance error correction circuit and a filter circuit, where the element performance error correction circuit is configured to generate an adjustment current based on the voltage signal output by the magnetoelectric conversion unit, and the filter circuit is configured to filter the high-frequency magnetic field signal coupled by the novel magnetoresistive element to ensure low-pass characteristics; and a multi-band feedback circuit including a plurality of dynamic output feedback control circuits, which is used to ensure the consistency of transmission characteristics of different frequencies, and each of the plurality of dynamic output feedback control circuits has a finite frequency band.

[0010] Furthermore, the feedback compensation unit includes a feedback winding uniformly wound around the iron core and configured to conduct a feedback current, a drive circuit 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 and is in the opposite direction to the primary magnetic field, and an output circuit configured to measure the feedback current value, determine a measured current value based on the feedback current value, and output the measured current value.

[0011] Furthermore, determining the measured current value based on the feedback current value includes dividing the feedback current value by the coil turns ratio to obtain the measured current value.

[0012] Furthermore, the AC / DC multi-air-gap magnetoresistive current sensor further includes an annular housing for mounting an iron core around which the feedback winding is wound and N newly developed magnetoresistive elements connected in parallel.

[0013] Furthermore, the annular housing achieves voltage insulation using an insulating layer.

[0014] According to a second aspect, an embodiment of the present invention further provides a current measurement method, which includes using the AC / DC multi-air-gap magnetoresistive current sensor according to each of the above embodiments to measure the measured current of a target energized wire, determining the measured current value, and outputting the measured current value, where the target energized wire is disposed at the center of the iron core of the AC / DC multi-air-gap magnetoresistive current sensor.

Advantages of the Invention

[0015] In the AC / DC multi-air-gap magnetoresistive current sensor and the current measurement method according to the embodiments of the present invention, the AC / DC multi-air-gap magnetoresistive current sensor adopts a multi-air-gap sub-band closed-loop iron core structure to improve the measurement performance of the current sensor, break through the problem of achieving both high-precision AC / DC current measurement and wide frequency range, provide technical guidance for the development and application of high-voltage and large-current measurement devices, and promote the technical improvement of high-voltage and large-current measurement devices.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0017] Hereinafter, exemplary embodiments of the present invention will be introduced with reference to the drawings. However, the present invention is not limited to the embodiments described herein and can be implemented in various forms. These embodiments are provided to fully and completely disclose the present invention and appropriately convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not for limiting the present invention. In the drawings, the same reference numerals are used for the same unit / element.

[0018] Unless otherwise defined, the terms (including scientific terms) used herein have meanings generally understood by those skilled in the art. And, as can be understood, terms defined in commonly used dictionaries should be understood to have consistent meanings in the context of the relevant art and should not be understood in an idealized or overly formal sense.

[0019] Fig. 1 shows an exemplary structural diagram of the AC / DC multi-air-gap magnetoresistive current sensor according to an embodiment of the present invention.

[0020] As shown in Fig. 1, the AC / DC multi-air-gap magnetoresistive current sensor is A magnetoelectric conversion unit 100 is provided, which is configured to acquire a magnetic field signal of a target energized wire 400 through which a current to be measured flows, convert the magnetic field signal into an electrical signal, and output the electrical signal to a signal processing unit 200. The magnetoelectric conversion unit 100 includes an iron core 101 and N (N≥3 and N is a positive integer) novel magnetoresistive elements 102 connected in parallel. N air gap openings 104 are symmetrically provided in the iron core 101, and the N novel magnetoresistive elements 102 are respectively arranged at the centers of the N air gap openings 104.

[0021] Furthermore, the iron core 101 is a circular magnetic flux collecting ring, and a feedback winding 301 is uniformly wound around the iron core 101. The magnetoelectric conversion unit further includes a power supply circuit 103 used to supply power by connecting to each of the N novel magnetoresistive elements 102.

[0022] When the target energized wire 400 through which the current to be measured flows is arranged at the center of the iron core 101, the N novel magnetoresistive elements 102 are used to acquire the magnetic field signal of the target energized wire 400 through which the current to be measured flows, convert the magnetic field signal into an electrical signal, and then output the electrical signal to the signal processing unit 200.

[0023] The above embodiments adopt a multi-air-gap sub-band closed-loop iron core structure, avoid the high interference sensitivity of the annular array current sensor due to the magnetic flux collecting effect of the iron core, avoid the wire eccentricity and non-uniform winding error of the single-air-gap iron core structure by the multi-air-gap, and avoid the hysteresis effect of the iron core by the zero magnetic flux closed-loop structure.

[0024] Furthermore, the fact that the N novel magnetoresistive elements acquire the magnetic field signal of the target energized wire through which the current to be measured flows, convert the magnetic field signal into an electrical signal, and then output the electrical signal to the signal processing unit is to obtain the input voltage V of each novel magnetoresistive element according to the following calculation formula (1), i whereby

Equation

[0025] Furthermore, the novel magnetoresistive element is a tunneling magnetoresistance (TMR) element.

[0026] The above embodiments employ novel magnetoresistive elements such as TMR, and have advantages such as high sensitivity and a wide frequency response range.

[0027] The signal processing unit 200 performs amplification processing on the electrical signal output by the magnetoelectric conversion unit 100, and then outputs it to the feedback compensation unit 300.

[0028] Furthermore, the signal processing unit 200 includes a detection circuit 201, an interference suppression circuit 202, and a multi-band feedback circuit 203.

[0029] The detection circuit 201 includes an instrumentation amplifier configured with three operational amplifiers. The detection circuit 201 amplifies the voltage signal output by the magnetoelectric conversion unit and then outputs it to the feedback compensation unit.

[0030] The interference suppression circuit 202 is used for the element performance error correction circuit and the filter circuit. The element performance error correction circuit generates an adjustment current based on the voltage signal output by the magnetoelectric conversion unit. The filter circuit filters the high-frequency magnetic field signal coupled by the novel magnetoresistive element in order to ensure low-pass characteristics.

[0031] The multi-band feedback circuit 203 includes several dynamic output feedback control circuits and is used to ensure the matching of transmission characteristics at different frequencies. Each of the dynamic output feedback control circuits has a finite frequency band.

[0032] The detection circuit amplifies the weak output voltage with a small amplitude of the TMR element and is used to perform processes such as calculation and filtering. The detection circuit is mainly composed of an instrumentation amplifier with a three-op amp configuration, and its REF terminal is grounded to maintain a low source impedance. A zero adjustment circuit is designed in the detection circuit. Two high-precision adjustable resistors are connected in series between two equivalent resistors, and a voltage follower is formed as a buffer using a high-precision op amp. The positive input terminal of the high-precision op amp is connected to the intermediate terminal of the high-precision adjustable resistor, and its output is used as the zero adjustment voltage output.

[0033] The interference suppression circuit includes an element performance error correction circuit and a filter circuit. The compensation method for element performance error correction based on the signal injection method is to identify the excitation signal from the current detected by the TMR element according to specific waveform characteristics through a decomposition unit, calculate the overall gain of the magnetic sensor measurement circuit, determine the change in the measurement characteristics of the magnetoresistive chip, and is used to generate an adjustment current. The filter circuit is used to filter the high-frequency magnetic field signals that may be coupled to ensure low-pass characteristics. The filter circuit employs a second-order Butterworth low-pass filter based on a high-precision op amp.

[0034] The multi-band feedback circuit is designed based on a split frequency band feedback mechanism. In the sensor circuit, the differences in the responses of current signals in different frequency ranges from low frequency to high frequency are determined, and for different frequency regions, a plurality of dynamic output feedback control circuits with finite frequency bands (i.e., each of the dynamic output feedback control circuits has a finite frequency band) are designed to ensure the matching of transmission characteristics at different frequencies.

[0035] The above embodiments adopt a multi-physics interference suppression method, correct zero drift in a detection circuit including zero drift correction, correct the error of element performance with an element error correction compensation circuit module based on the signal injection method, and filter the electromagnetic interference signals that may be coupled with an electromagnetic interference filter. Adopt a split frequency band feedback mechanism to ensure the consistency of the transmission characteristics of different frequencies.

[0036] The feedback compensation unit 300 is configured to adjust the feedback current based on the amplified voltage signal output by the signal processing unit 200 so that the new magnetoresistive element can always operate with zero magnetic flux, measure the feedback current value, obtain the measured current value based on the feedback current value, and output the measured current value.

[0037] Furthermore, the feedback compensation unit 300 includes a feedback winding 301, a drive circuit 302, and an output circuit 303.

[0038] The feedback winding 301 is uniformly wound around the iron core and is configured to conduct a feedback current.

[0039] The drive 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 is in the opposite direction.

[0040] The output circuit 303 is configured to measure the feedback current value, obtain the measured current value based on the feedback current value, and output the measured current value.

[0041] Furthermore, obtaining the measured current value based on the feedback current value includes dividing the feedback current value by the coil turns ratio to obtain the measured current value.

[0042] The amplified output voltage drives a push-pull transistor and outputs a feedback current I to a compensation coil wound around the iron core cAdjust it so that the compensation magnetic field has the same magnitude as the primary magnetic field and is in the opposite direction, and operate the TMR element always near zero magnetic flux. At this time, I c and the primary current I in The ratio to is the ratio of the number of coil turns. Then, by measuring the resistance, the voltage of the feedback current I c is measured, and the measurement result of I in can be obtained. At this time, the magnitude of the actual magnetic field on the sensor is the difference between the external magnetic field and the feedback magnetic field, and the sensor actually operates within a very small magnetic field range.

[0043] Furthermore, the AC-DC multi-air-gap magnetoresistive current sensor further includes an iron core around which a feedback winding is wound and a ring-shaped housing for mounting N newly developed magnetoresistive elements connected in parallel. The ring-shaped housing achieves voltage insulation using a ring-shaped insulating layer of a special process.

[0044] Furthermore, the ring-shaped housing achieves voltage insulation using an insulating layer.

[0045] FIG. 2 shows an exemplary structural diagram of the housing of the AC-DC multi-air-gap magnetoresistive current sensor according to an embodiment of the present invention. As shown in FIG. 2, the ring-shaped housing, the iron core around which the feedback winding is wound, and the N newly developed magnetoresistive elements mounted inside the ring-shaped housing can form a sensing ring. The inside of the sensing ring achieves voltage insulation by a ring-shaped insulating layer of a special process, and the power supply and the secondary circuit can realize current sensing on the low voltage side.

[0046] By adopting the ring-shaped housing, the insulation performance of the sensor is guaranteed.

[0047] The above embodiments provide an AC-DC multi-air-gap magnetoresistive current sensor, adopt a multi-air-gap sub-band closed-loop iron core structure to improve the measurement performance of the current sensor, break through the problem of achieving both high-precision AC-DC current measurement and wide frequency range, provide technical guidance for the development and application of high-voltage large-current measurement equipment, and promote the technical improvement of high-voltage large-current measurement equipment.

[0048] An embodiment of the present invention further provides a current measurement method, which employs the AC-DC multi-air-gap magnetoresistive current sensor according to each of the above embodiments to measure the measured current of the target energized wire, obtain the measured current value, and output the measured current value. Here, the target energized wire is arranged at the center of the core of the AC-DC multi-air-gap magnetoresistive current sensor.

[0049] The embodiments of the present invention design an AC-DC multi-air-gap magnetoresistive current sensor and a current measurement method, avoid the high interference sensitivity of the annular array current sensor, reduce the influence of errors such as wire eccentricity and external interference, avoid the hysteresis effect of the core, and can break through the problem of achieving both high precision and wide frequency range in high-voltage and large-current DC measurement.

[0050] The AC-DC multi-air-gap magnetoresistive current sensor mainly includes a magnetoelectric conversion unit, a signal processing unit, and a feedback compensation unit.

[0051] The magnetoelectric conversion unit is composed of a core, four TMR elements, and a power supply circuit. Here, the core is circular, the cross-section is square, and it is made of an iron-based nanocrystalline alloy or permalloy material. A feedback winding is uniformly wound around the core, and four air-gap openings are symmetrically arranged on the core.

[0052] The four TMR elements of the magnetoelectric conversion unit are respectively installed at the centers of the four air gaps of the core. When the core is placed on the energized wire through which the measured current I_in flows, the calculation formula for the input voltage of each TMR element can refer to the aforementioned formula (1).

[0053] Since the energized wire may not be located at the center of the core, the primary magnetic fields respectively induced by the primary current in the air gaps are different. At the i-th TMR element, the total magnetic field formed by the primary magnetic field and the feedback magnetic field in the air gap

Chemical formula

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[0054] The power supply circuit of the magnetoelectric conversion unit selects an LDO (Low Dropout Regulator) chip as the power supply for the TMR element, uses a 2.2 μF small ceramic output capacitor to maintain the stability of the fixed output voltage, and supplies power to the four TMR elements. Here, a temperature drift error correction and compensation circuit based on a thermistor is designed, and an in-phase proportional amplification circuit is configured with a negative temperature coefficient thermistor to adjust the power supply voltage of the TMR sensing chip when the temperature changes.

[0055] The signal processing unit is composed of a detection circuit, an interference suppression circuit, and a multi-band feedback circuit. The detection circuit is used to amplify the weak output voltage with a small amplitude of the TMR element and perform processes such as calculation and filtering. The detection circuit is mainly composed of an instrumentation amplifier with a three-opamp configuration, and its REF terminal is grounded to maintain a low source impedance. A zero adjustment circuit is designed for the detection circuit. Two high-precision adjustable resistors are connected in series between two equivalent resistors, and a voltage follower is formed as a buffer using a high-precision opamp. The positive input terminal of the high-precision opamp is connected to the intermediate terminal of the high-precision adjustable resistor, and its output is used as the zero adjustment voltage output.

[0056] The interference suppression circuit of the signal processing unit includes an element performance error correction circuit and a filter circuit. The compensation method for element performance error correction based on the signal injection method identifies the excitation signal from the current detected by the TMR element according to specific waveform characteristics through a decomposition unit, calculates the overall gain of the magnetic sensor measurement circuit, determines the change in the measurement characteristics of the magnetoresistive chip, and is used to generate an adjustment current. The filter circuit is used to filter the high-frequency magnetic field signal that may be coupled in order to ensure the low-pass characteristic, and the filter circuit employs a second-order Butterworth low-pass filter constructed based on a high-precision operational amplifier.

[0057] The multi-band feedback circuit of the signal processing unit is designed based on the split frequency band feedback mechanism. In the sensor circuit, based on the difference in the responses of current signals at different frequencies, multiple dynamic output feedback control circuits (each dynamic output feedback control circuit has a finite frequency band) are designed with the goal of ensuring the consistency of the transmission characteristics at different frequencies from low frequency to high frequency signal.

[0058] The feedback compensation unit is composed of a drive circuit, a feedback winding, and an output resistor. The amplified output voltage drives a push-pull transistor, and the transistor outputs a feedback current to the compensation coil.

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Mathematical formula

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[0059] The design scheme of the external structure of the current sensor is to design the magnetoelectric conversion part as a sensing ring based on the above high-voltage DC quantum tunneling magnetoresistive current sensing method. Inside the sensing ring, voltage insulation is achieved by a special process annular insulating layer, and the power supply and the secondary circuit realize current sensing on the low-voltage side.

[0060] The present invention designs an AC / DC multi-air-gap magnetoresistive current sensor and a current measurement method, and includes the following technical solutions.

[0061] (1) Multi - air - gap sub - band closed - loop core structure: By the magnetic flux concentrating effect of the core, the high interference sensitivity of the circular array current sensor is avoided; by the multi - air - gap, the wire eccentricity and non - uniform winding error of the single - air - gap core structure are avoided; and by the zero - magnetic - flux closed - loop structure, the hysteresis effect of the core is avoided.

[0062] (2) Multiphysics interference suppression method: The temperature drift error is corrected by a power supply with a temperature drift error correction and compensation circuit, the zero - drift is corrected by a detection circuit including zero - drift correction, the error of the element performance is corrected by an element error correction and compensation circuit module based on the signal injection method, and the electromagnetic field interference signals that may be coupled are filtered by an electromagnetic field interference filter.

[0063] (3) Sub - band feedback mechanism: Ensure the consistency of transmission characteristics at different frequencies.

[0064] (4) External structure design with an annular insulating layer: Ensure the insulation performance of the sensor.

[0065] Through the above - mentioned technical solutions, the measurement performance of the quantum - tunneling magnetoresistive current sensor is improved, the problem of achieving both high - precision AC and DC current measurement and wide - frequency - range compatibility is broken through, technical guidance for the development and application of high - voltage and large - current measurement equipment is provided, and the technical improvement of high - voltage and large - current measurement equipment is promoted.

[0066] The present invention provides an AC - DC multi - air - gap magnetoresistive current sensor, mainly comprising a magnetoelectric conversion unit, a signal processing unit, and a feedback compensation unit.

[0067] The magnetoelectric conversion unit is composed of a core, a power supply circuit, and four TMR elements. Here, the core is circular, the cross - section is square, made of an iron - based nanocrystalline alloy or permalloy material, a feedback winding is uniformly wound around the core, four air - gap openings are symmetrically arranged on the core, and the four TMR elements are respectively arranged at the centers of the four air - gaps of the core. The synthesized output voltage of the TMR element is input to the signal processing unit.

[0068] The power supply circuit of the magnetoelectric conversion unit selects an LDO chip as the power supply for the TMR element, uses a 2.2 μF small ceramic output capacitor to maintain the stability of the fixed output voltage, and supplies power to four TMR elements. Here, a temperature drift error correction and compensation circuit based on a thermistor is designed, and a non-inverting proportional amplifier circuit is formed by a negative temperature coefficient thermistor to adjust the power supply voltage of the TMR sensing chip when the temperature changes.

[0069] The signal processing unit is composed of a detection circuit, an interference suppression circuit, and a multi-band feedback circuit. The detection circuit amplifies the weak output voltage with a small amplitude of the TMR element and is used for processing such as calculation and filtering. The detection circuit is mainly composed of an instrumentation amplifier with a three-op amp configuration, and its REF terminal is grounded to maintain a low source impedance. A zero adjustment circuit is designed for the detection circuit. Two high-precision adjustable resistors are connected in series between two equivalent resistors, and a voltage follower is formed as a buffer using a high-precision op amp. The positive input terminal of the high-precision op amp is connected to the intermediate terminal of the high-precision adjustable resistor, and its output is used as the zero adjustment voltage output.

[0070] The interference suppression circuit includes an element performance error correction circuit and a filter circuit. The compensation method for element performance error correction based on the signal injection method is to identify the excitation signal from the current detected by the TMR element according to specific waveform characteristics through a decomposition unit, calculate the overall gain of the magnetic sensor measurement circuit, determine the change in the measurement characteristics of the magnetoresistive chip, and is used to generate an adjustment current. The filter circuit is used to filter out high-frequency magnetic field signals that may be coupled to ensure low-pass characteristics. The filter circuit adopts a second-order Butterworth low-pass filter built based on a high-precision op amp.

[0071] The multi-band feedback circuit is designed based on a split-frequency band feedback mechanism. In the sensor circuit, based on the difference in the responses of current signals at different frequencies, multiple dynamic output feedback control circuits are designed with the goal of ensuring the consistency of transmission characteristics at different frequencies from low to high frequency signals. Each dynamic output feedback control circuit corresponds to a finite frequency band.

[0072] The feedback compensation unit is composed of a drive circuit, a feedback winding, and an output resistor. The amplified output voltage drives a push-pull transistor, and the transistor outputs a feedback current I_c to the compensation coil. At this time, the actual magnitude of the magnetic field on the sensor is the difference between the external magnetic field and the feedback magnetic field. At this time, when measuring the feedback current using Ohm's law, the measured current can be obtained using the ratio of the compensation coil.

[0073] The design scheme of the external structure of the current sensor is to design the magnetoelectric conversion unit as a sensing ring based on the above high-voltage DC quantum tunneling magnetoresistive current sensing method. Inside the sensing ring, voltage insulation is achieved by a special process annular insulating layer, and the power supply and the secondary circuit realize current sensing on the low-voltage side.

[0074] The present invention has been described with reference to several embodiments. However, as is known to those skilled in the art, other embodiments of the present invention other than those described above are also included within the scope of the present invention as limited by the appended claims.

[0075] In general, all terms used in the claims are to be construed according to their ordinary meaning in the technical field, unless otherwise defined. Any reference to "one / the / said [device, component, etc.]" is to be explicitly construed as an example of at least one of the said device, component, etc., unless otherwise defined. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless otherwise defined.

[0076] Those skilled in the art will understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can adopt the form of completely hardware embodiments, completely software embodiments, or embodiments combining software and hardware. Furthermore, the present invention can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0077] The present invention will be described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It will be understood that each process and / or block in the flowchart and / or block diagram, and combinations of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. To generate one machine, by providing these computer program instructions to the processor of a general-purpose computer, a dedicated computer, an embedded processor, or other programmable data processing device, instructions executed by the processor of the computer or other programmable data processing device are caused to generate an apparatus for performing the functions specified in one or more processes of the flowchart and / or one or more blocks of the block diagram.

[0078] These computer program instructions can also be stored in a computer-readable memory that causes a computer or other programmable data processing device to operate in a specific manner, and a product including instruction means for embodying the functions specified in one or more processes of the flowchart and / or one or more blocks of the block diagram is generated by the instructions stored in the computer-readable memory.

[0079] These computer program instructions can be loaded into a computer or other programmable data processing apparatus to cause the computer or other programmable apparatus to perform a series of operational steps to generate a process implemented on the computer, whereby the instructions executed on the computer or other programmable apparatus provide steps for embodying the functions specified in one or more processes of the flowchart and / or one or more blocks of the block diagram.

[0080] Finally, it should be noted that the above embodiments are only for explaining the technical solutions of the present invention and are not limitations thereto. Although the present invention has been described in detail with reference to the above embodiments, as can be understood by those skilled in the art, still, the specific embodiments of the present invention can be modified or replaced by the same party, and any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should all be included within the protection scope of the claims of the present invention.

Industrial Applicability

[0081] In an embodiment of the present invention, the magnetoelectric conversion unit is configured to acquire a magnetic field signal of a target energized wire through which a measured current flows, convert the magnetic field signal into an electrical signal and output it to the signal processing unit. The magnetoelectric conversion unit adopts a multi-air-gap sub-band closed-loop core structure. The signal processing unit is configured to perform an amplification process on the electrical signal and then output it to the feedback compensation unit. The feedback compensation unit is configured to adjust a feedback current based on the amplified voltage signal so that a new type of magnetoresistive element can always operate with zero magnetic flux, measure the feedback current value, obtain a measured current value based on the feedback current value, and output the measured current value. In this way, the AC / DC multi-air-gap magnetoresistive current sensor adopts a multi-air-gap sub-band closed-loop core structure to improve the measurement performance of the current sensor, break through the problem of achieving both high-precision AC / DC current measurement and wide frequency range, provide technical guidance for the development and application of high-voltage and large-current measurement devices, and promote the technical improvement of high-voltage and large-current measurement devices.

Claims

1. A multi - air - gap magnetoresistive current sensor for AC and DC, comprising: A magnetoelectric conversion unit configured to acquire a magnetic field signal of a target current - carrying wire through which a current to be measured flows, convert the magnetic field signal into an electrical signal, and output the electrical signal to a signal processing unit. The magnetoelectric conversion unit includes an iron core and N (N≥3 and N is a positive integer) newly - type magnetoresistive elements connected in parallel. N air - gap openings are symmetrically provided in the iron core, and the N newly - type magnetoresistive elements are respectively arranged at the centers of the N air - gap openings. A signal processing unit configured to perform an amplification process on the electrical signal output by the magnetoelectric conversion unit and then output the amplified signal to a feedback compensation unit. A feedback compensation unit configured to adjust a feedback current based on the amplified voltage signal output by the signal processing unit so that the newly - type magnetoresistive element can always operate with zero magnetic flux, measure the feedback current value, obtain the current value to be measured based on the feedback current value, and output the current value to be measured. The multi - air - gap magnetoresistive current sensor for AC and DC comprises the above components.

2. The iron core is a circular magnetic flux - collecting ring, and a feedback winding is uniformly wound thereon. The magnetoelectric conversion unit further includes a power supply circuit used to supply power by connecting to each of the N newly - type magnetoresistive elements. When the target current - carrying wire through which the current to be measured flows is arranged at the center of the iron core, the N newly - type magnetoresistive elements are used to acquire the magnetic field signal of the target current - carrying wire through which the current to be measured flows, convert the magnetic field signal into an electrical signal, and then output the electrical signal to the signal processing unit. The multi - air - gap magnetoresistive current sensor for AC and DC according to Claim 1.

3. The act that the N newly - type magnetoresistive elements acquire the magnetic field signal of the target current - carrying wire through which the current to be measured flows, convert the magnetic field signal into an electrical signal, and then output the electrical signal to the signal processing unit includes: The input voltage V of each novel magnetoresistive element is obtained by the following equation, ｉ which is as follows. 【Number 11】 K ｉ is the sensitivity of the i-th novel magnetoresistive element, and I ｉ is the control current of the i-th novel magnetoresistive element, B ｉｎ is the primary magnetic field, and B ｃ is the compensation magnetic field generated by the feedback current, and Based on the input voltage of each newly - type magnetoresistive element, obtaining the combined voltage of the N newly - type magnetoresistive elements by equivalent circuit synthesis of parallel capacitors, and outputting the combined voltage to the signal processing unit. The multi - air - gap magnetoresistive current sensor for AC and DC according to Claim 2.

4. The newly - type magnetoresistive element is a tunnel magnetoresistive element. The multi - air - gap magnetoresistive current sensor for AC and DC according to Claim 2.

5. The signal processing unit is a detection circuit including an instrumentation amplifier with a three-op amp configuration, which is configured to amplify the voltage signal output by the magnetoelectric conversion unit and then output it to the feedback compensation unit. an interference suppression circuit used for the element performance error correction circuit and the filter circuit. The element performance error correction circuit is configured to generate an adjustment current based on the voltage signal output by the magnetoelectric conversion unit, and the filter circuit is configured to filter the high-frequency magnetic field signal coupled by the new magnetoresistive element to ensure the low-pass characteristic. a multi-band feedback circuit including a plurality of dynamic output feedback control circuits, which is used to ensure the consistency of the transmission characteristics of different frequencies. Each of the plurality of dynamic output feedback control circuits has a finite frequency band. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2.

6. The feedback compensation unit is a feedback winding uniformly wound around the iron core and configured to carry a feedback current. a drive circuit 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 is in the opposite direction. an output circuit configured to measure the feedback current value, obtain the measured current value based on the feedback current value, and output the measured current value. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 2.

7. Obtaining the measured current value based on the feedback current value includes dividing the feedback current value by the coil turn ratio to obtain the measured current value. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 6.

8. The AC / DC multi-air-gap magnetoresistive current sensor further includes an annular housing for mounting an iron core around which the feedback winding is wound and N newly developed magnetoresistive elements connected in parallel. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 6.

9. The annular housing achieves voltage insulation using an insulating layer. The AC / DC multi-air-gap magnetoresistive current sensor according to claim 8.

10. A current measurement method, which includes using the AC / DC multi-air-gap magnetoresistive current sensor according to any one of claims 1 to 9 to measure the current to be measured of a target energized wire, obtaining a value of the current to be measured, and outputting the value of the current to be measured, wherein the target energized wire is arranged at the center of the core of the AC / DC multi-air-gap magnetoresistive current sensor.

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