Broadband weak current sensing method and system for distribution network voltage inversion

Abstract

The invention provides a broadband weak current sensing method and system for distribution network voltage inversion. The system comprises a tunneling reluctance magnetic core, a feedback coil, an open magnetic ring, a sampling resistor and a feedback conditioning circuit. One side, close to the feedback conditioning circuit, of the open magnetic ring is provided with an opening; the number of the tunneling magnetic resistance magnetic cores is two, and the two tunneling magnetic resistance magnetic cores are symmetrically arranged with the center of the opening of the opening magnetic ring as the symmetry point and used for obtaining two current data with opposite sensitivity directions. The two tunneling magnetic resistance magnetic cores are connected with one end of the feedback conditioning circuit, and the other end of the feedback conditioning circuit is sequentially connected with the feedback coil and the sampling resistor; according to the invention, two pieces of tunneling magnetic resistance magnetic cores are symmetrically arranged in the current sensor, so that feedback current data with opposite sensitivity directions are obtained, high-precision induction current output data are obtained after offset voltage and temperature drift correction, and high-precision data support can be provided for subsequent voltage inversion and related work.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric power system current measurement, and in particular relates to a broadband weak current sensing method and system for distribution network voltage inversion. Background Art

[0002] With the access of large-scale wind power, distributed photovoltaic and other new energy sources to the distribution network and the large-scale construction of rail transit, the degree of power electronics in the distribution and power supply system has increased rapidly. The high degree of power electronics and strong nonlinear characteristics make the power disturbance phenomenon in the power grid complicated. The switching frequency of power electronic components is high, and the harmonics injected into the power grid by the converter extend to high frequency. A large number of equipment in the distribution network have significant frequency-varying characteristics, and the loss and discharge characteristics of electrical equipment are closely related to the voltage and waveform. The impedance changes sharply with the increase of frequency. Under the influence of broadband disturbance, the dielectric loss increases, causing the equipment to heat up and the insulation to age faster, which in turn affects the reliability of the equipment. Therefore, accurate perception of the broadband voltage characteristics of the distribution network is an important parameter for characterizing the transient fault information of the distribution network and supporting the perception and control of the distribution and power supply. At present, the new broadband voltage perception method can realize indirect measurement from voltage to current and then to the distribution network voltage through the non-contact perception of the grounding current of the capacitive equipment and the broadband current-voltage inversion mechanism, and obtain the broadband voltage characteristics, which has the outstanding advantages of not changing the primary wiring and high safety.

[0003] The existing non-contact current sensing method senses the current based on the tunneling magnetoresistance effect. However, the induced current data obtained by the tunneling magnetoresistance current sensor contains an offset caused by temperature changes and an offset caused by the offset voltage when the measuring device itself is working. These two offsets are difficult to correct directly in the induced current data, which leads to the problem of distortion in the accuracy of the measured current data. In addition, the current measurement accuracy of the current sensor based on the tunneling magnetoresistance core is also affected by the physical properties of the tunneling magnetoresistance core itself. The higher the measurement accuracy, the higher the influence of the physical properties of the tunneling magnetoresistance core on the measurement accuracy. At present, there is no clear solution to screen the tunneling magnetoresistance core based on the measurement accuracy. Finally, due to the lack of high-precision non-contact current sensing data, there is still room for improvement in the accuracy of the non-contact inversion voltage value in the existing technology. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention proposes a dual tunneling magnetoresistive core current sensor, comprising: a tunneling magnetoresistive core, a feedback coil, an open magnetic ring, a sampling resistor and a feedback conditioning circuit; the open magnetic ring has an opening on a side close to the feedback conditioning circuit; the tunneling magnetoresistive core is composed of two pieces, and the two tunneling magnetoresistive cores are symmetrically arranged with the center of the opening of the open magnetic ring as a symmetry point, so as to obtain two current data with opposite sensitivity directions;

[0005] The two tunneling magnetoresistive cores are connected to one end of the feedback conditioning circuit, the other end of the feedback conditioning circuit is connected to the feedback coil and the sampling resistor in sequence, the feedback coil is wound on the open magnetic ring, and the sampling resistor is grounded.

[0006] Preferably, the feedback conditioning circuit includes a three-stage operational amplifier instrumentation amplifier and a differential summing circuit, the two tunneling magnetoresistive cores are connected to one end of the three-stage operational amplifier instrumentation amplifier, the other end of the three-stage operational amplifier instrumentation amplifier is connected to one end of the differential summing circuit, and the other end of the differential summing circuit is connected to the feedback coil.

[0007] Based on the same inventive concept, the present invention application also provides a method for selecting a dual tunneling magnetoresistive core current sensor, comprising:

[0008] Get the accuracy range of the data to be tested;

[0009] Based on the passing noise analysis mechanism and the wideband selection mechanism, determining the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured;

[0010] Based on the tunneling magnetoresistive core parameters, determining a dual tunneling magnetoresistive core current sensor;

[0011] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0012] Preferably, the tunneling magnetoresistive core parameters include: resistance of the tunneling magnetoresistive core, a parasitic voltage value range, and a normalized noise spectrum density value range.

[0013] Preferably, the accuracy range of the data to be measured includes: the minimum current value of the data to be measured, the upper frequency limit value of the data to be measured, and the lower frequency limit value of the data to be measured; the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the wideband selection mechanism include:

[0014] Based on the minimum current value of the data to be measured, the minimum magnetic field value at the tunneling magnetoresistive core is simulated and calculated using simulation software;

[0015] Based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured, the normalized noise spectrum density value range of the tunneling magnetoresistive core is calculated through a noise analysis mechanism;

[0016] Based on the upper frequency limit of the data to be measured, the resistance and parasitic voltage value ranges of the tunneling magnetoresistive core are calculated through a wide-band selection mechanism.

[0017] Preferably, the calculation of the normalized noise spectrum density value range of the tunneling magnetoresistive core based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured, and the lower frequency limit value of the data to be measured by a noise analysis mechanism includes:

[0018] Calculating the background noise peak value of the tunneling magnetoresistive core based on the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured;

[0019] Based on the minimum magnetic field value at the tunneling magnetoresistive core and the background noise peak value of the tunneling magnetoresistive core, a noise analysis mechanism is adopted to obtain a value range of a normalized noise spectrum density of the tunneling magnetoresistive core.

[0020] Preferably, the noise analysis mechanism is expressed as follows:

[0021]

[0022] Among them, E f The peak value of the background noise of the tunnel magnetoresistive core is affected; e fnorm is the normalized noise spectrum density of the tunneling magnetoresistive core; f H is the upper limit of the frequency of the data to be tested; f L is the lower limit of the frequency of the data to be measured; B1 is the minimum magnetic field value at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model;

[0023] The broadband selection mechanism is expressed as follows:

[0024]

[0025] Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H is the upper limit of the frequency of the data to be tested.

[0026] Based on the same inventive concept, the present invention also provides a selection system for a dual tunneling magnetoresistive core current sensor, comprising:

[0027] Data acquisition module: used to obtain the accuracy range of the data to be tested;

[0028] Parameter determination module: used to determine the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the wide-band selection mechanism;

[0029] A current sensor selection module: used to determine a dual tunneling magnetoresistive core current sensor based on the tunneling magnetoresistive core parameters;

[0030] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0031] Preferably, the tunneling magnetoresistive core parameters include: resistance of the tunneling magnetoresistive core, a parasitic voltage value range, and a normalized noise spectrum density value range.

[0032] Preferably, the accuracy range of the data to be measured includes: a minimum current value of the data to be measured, an upper frequency limit value of the data to be measured, and a lower frequency limit value of the data to be measured;

[0033] The parameter determination module comprises:

[0034] A simulation calculation submodule: used to simulate and calculate the minimum magnetic field value at the tunneling magnetoresistive core using simulation software based on the minimum current value of the data to be measured;

[0035] Noise analysis submodule: used to calculate the normalized noise spectrum density value range of the tunneling magnetoresistive core through a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured;

[0036] Broadband selection mechanism submodule: used to calculate the resistance and parasitic voltage value range of the tunneling magnetoresistive core through a broadband selection mechanism based on the upper frequency limit of the data to be measured.

[0037] Preferably, the noise analysis submodule includes:

[0038] A background noise peak value calculation unit: specifically used to calculate the background noise peak value of the tunneling magnetoresistive core based on the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured;

[0039] Normalized noise spectrum density calculation unit: specifically used to obtain the value range of the normalized noise spectrum density of the tunneling magnetoresistive core by adopting a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core and the background noise peak value of the tunneling magnetoresistive core.

[0040] Preferably, the noise analysis mechanism is expressed as follows:

[0041]

[0042] Among them, E f The peak value of the background noise of the tunnel magnetoresistive core is affected; e fnorm is the normalized noise spectrum density of the tunneling magnetoresistive core; f H is the upper limit of the frequency of the data to be tested; f L is the lower limit of the frequency of the data to be measured; B1 is the minimum magnetic field value at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model;

[0043] The broadband selection mechanism is expressed as follows:

[0044]

[0045] Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H is the upper limit of the frequency of the data to be tested.

[0046] Based on the same inventive concept, the present invention also provides a broadband weak current sensing method for distribution network voltage inversion, comprising:

[0047] The feedback current is processed into two current data with opposite sensitivity directions through a dual tunnel magnetoresistive core current sensor;

[0048] According to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, a composite offset voltage correction is performed on the two current data with opposite sensitivity directions to obtain standard feedback current data;

[0049] Inputting the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal;

[0050] Based on historical experimental current sensing output signal data, temperature drift compensation is performed on the current sensing output signal to obtain a high-precision current sensing output signal;

[0051] Based on the high-precision current sensing output signal, a non-contact wideband high-precision voltage value of the distribution network is obtained through voltage inversion;

[0052] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0053] Preferably, the method of performing composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data includes:

[0054] According to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, the current data in the two sensitivity directions are corrected for the core offset voltage to obtain the corrected current data in the two sensitivity directions;

[0055] Based on the corrected current data in the two sensitivity directions, a circuit offset voltage correction is performed through a differential summation algorithm to obtain standard feedback current data.

[0056] Preferably, the current data in the two sensitivity directions are corrected for core offset voltage according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain the corrected current data in the two sensitivity directions, including:

[0057] Based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, and according to the offset voltage calculation formula corresponding to the tunneling magnetoresistive core, estimating the offset voltage value of the tunneling magnetoresistive core;

[0058] According to the offset voltage value of the tunnel magnetoresistive core, the current data in the two sensitivity directions are corrected for the core offset voltage to obtain the corrected current data in the two sensitivity directions.

[0059] Preferably, the historical experimental current sensing output signal data includes: a plurality of experimental output signal values ​​and output signal standard values; based on the historical experimental current sensing output signal data, the current sensing output signal is subjected to temperature drift compensation to obtain a high-precision current sensing output signal, including:

[0060] Based on the current temperature value, determine several experimental output signal values ​​and standard output signal values ​​at the current temperature;

[0061] Based on a plurality of experimental output signal values ​​and a standard output signal value at the current temperature, calculating an average value of a plurality of differences between the experimental output signal value and the standard output signal value;

[0062] Determine a temperature drift correction factor corresponding to the current temperature based on the average value;

[0063] Based on the temperature drift correction factor corresponding to the current temperature, the temperature drift compensation is performed on the current sensing output signal to obtain a high-precision current sensing output signal.

[0064] Preferably, the current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual-tunneling magnetoresistive core current sensor, combined with the output characteristics of the designed circuit in the dual-tunneling magnetoresistive core current sensor.

[0065] Preferably, the designed circuit output characteristics include: a circuit gain of a signal processing unit and a circuit gain of an out-of-loop adjustment unit; the current sensing output signal includes: a current output signal and a voltage output signal;

[0066] The expression of the current sensing model is as follows:

[0067]

[0068] V2=K2V1=K2I3R0

[0069] I1=NI3+σ

[0070] Among them, I3 is the standard feedback current data; I1 is the measured current; I2 is the current output signal; S is the sensitivity of the dual tunneling magnetoresistive core current sensor; K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the dual tunneling magnetoresistive core current sensor; R0 is the resistance of the dual tunneling magnetoresistive core current sensor; V1 is the closed-loop output voltage; V2 is the voltage output voltage; σ is the measurement error.

[0071] Based on the same inventive concept, the present invention also provides a non-contact broadband weak current sensing system for distribution network voltage inversion, comprising:

[0072] Feedback current acquisition module: used to process the feedback current into two current data with opposite sensitivity directions through a dual tunneling magnetoresistive core current sensor;

[0073] Composite offset voltage correction module: used to perform composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data;

[0074] Current sensing module: used to input the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal;

[0075] Temperature drift compensation module: used to perform temperature drift compensation on the current sensing output signal based on historical experimental current sensing output signal data to obtain a high-precision current sensing output signal;

[0076] Voltage inversion module: used to obtain a non-contact broadband high-precision voltage value of the distribution network through voltage inversion based on the high-precision current sensing output signal;

[0077] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0078] Preferably, the composite offset voltage correction module includes:

[0079] A core offset voltage correction submodule: used to perform core offset voltage correction on the current data in the two sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, so as to obtain corrected current data in the two sensitivity directions;

[0080] Circuit offset voltage correction submodule: used to perform circuit offset voltage correction based on the corrected current data in the two sensitivity directions through a differential summation algorithm to obtain standard feedback current data.

[0081] Preferably, the magnetic core offset voltage correction submodule includes:

[0082] A core offset voltage estimation unit: used to estimate the offset voltage value of the tunneling magnetoresistive core based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor and according to the offset voltage calculation formula corresponding to the tunneling magnetoresistive core;

[0083] A core voltage correction unit is used to perform core offset voltage correction on the current data in the two sensitivity directions according to the offset voltage value of the tunnel magnetoresistive core, so as to obtain corrected current data in the two sensitivity directions.

[0084] Preferably, the historical experimental current sensing output signal data includes: a number of experimental output signal values ​​and output signal standard values;

[0085] The temperature drift compensation module comprises:

[0086] Standard value determination unit: used to determine several experimental output signal values ​​and standard output signal values ​​at the current temperature based on the current temperature value;

[0087] A difference calculation unit is used to calculate an average value of a plurality of differences between the experimental output signal value and the standard output signal value based on a plurality of experimental output signal values ​​and a standard output signal value at the current temperature;

[0088] A temperature drift correction factor determination unit: used to determine a temperature drift correction factor corresponding to the current temperature based on the average value;

[0089] A temperature drift correction unit is used to perform temperature drift compensation on the current sensing output signal based on the corresponding temperature drift correction factor at the current temperature to obtain a high-precision current sensing output signal.

[0090] Preferably, the current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual-tunneling magnetoresistive core current sensor, combined with the output characteristics of the designed circuit in the dual-tunneling magnetoresistive core current sensor.

[0091] Preferably, the designed circuit output characteristics include: a circuit gain of a signal processing unit and a circuit gain of an out-of-loop adjustment unit; the current sensing output signal includes: a current output signal and a voltage output signal;

[0092] The expression of the current sensing model is as follows:

[0093]

[0094] V2=K2V1=K2I3R0

[0095] I1=NI3+σ

[0096] Among them, I3 is the standard feedback current data; I1 is the measured current; I2 is the current output signal; S is the sensitivity of the dual tunneling magnetoresistive core current sensor; K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the dual tunneling magnetoresistive core current sensor; R0 is the resistance of the dual tunneling magnetoresistive core current sensor; V1 is the closed-loop output voltage; V2 is the voltage output voltage; σ is the measurement error.

[0097] Based on the same inventive concept, the present invention also provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0098] The memory is used to store one or more programs;

[0099] When the one or more programs are executed by the at least one processor, a method for selecting a dual-tunneling magnetoresistive core current sensor as described in any of the preceding items, or a wide-band weak current sensing method for distribution network voltage inversion as described in any of the preceding items is implemented.

[0100] Based on the same inventive concept, the present invention also provides a readable storage medium having an execution program stored thereon. When the execution program is executed, it implements a method for selecting a dual-tunneling magnetoresistive core current sensor as described in any of the preceding items, or a wide-band weak current sensing method for distribution network voltage inversion as described in any of the preceding items.

[0101] Compared with the closest prior art, the present invention has the following beneficial effects:

[0102] The present invention provides a dual tunneling magnetoresistive core current sensor including: a tunneling magnetoresistive core, a feedback coil, an open magnetic ring, a sampling resistor and a feedback conditioning circuit; the open magnetic ring has an opening on one side close to the feedback conditioning circuit; the tunneling magnetoresistive core is composed of two pieces, and the two tunneling magnetoresistive cores are symmetrically arranged with the center of the opening of the open magnetic ring as a symmetric point, so as to obtain two current data with opposite sensitivity directions; the two tunneling magnetoresistive cores are connected to one end of the feedback conditioning circuit, and the other end of the feedback conditioning circuit is connected to the feedback coil and the sampling resistor in turn, the feedback coil is wound on the open magnetic ring, and the sampling resistor is grounded. The present invention can obtain two current data with opposite sensitivity directions through two tunneling magnetoresistive cores. Although the current directions in the current data are opposite, the directions of the temperature drift offset and the offset voltage offset remain unchanged, and then the offset can be offset by calculation, thereby obtaining high-precision current data; in addition, the dual tunneling magnetoresistive core current sensor also has the advantages of non-contact measurement, high precision, small size, easy installation and low cost.

[0103] The present invention provides a method for selecting a dual tunneling magnetoresistive core current sensor, comprising: obtaining the accuracy range of the data to be measured; determining the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on a noise analysis mechanism and a broadband selection mechanism; determining a dual tunneling magnetoresistive core current sensor based on the tunneling magnetoresistive core parameters; wherein the dual tunneling magnetoresistive core current sensor is the current sensor as described above. The present invention provides a method for selecting a tunneling magnetoresistive core based on a noise analysis mechanism and a broadband selection mechanism, which can determine the corresponding physical performance parameter range of the tunneling magnetoresistive core according to the accuracy range of the data to be measured, select the tunneling magnetoresistive core according to the parameter range, ensure the accuracy of broadband weak current perception and the wide measurement frequency range, improve the current perception accuracy, meet the needs of broadband high-precision current perception in the distribution network, and provide reliable current perception data for broadband voltage inversion in the distribution network.

[0104] The present invention provides a broadband weak current sensing method for distribution network voltage inversion, comprising: processing the feedback current into two current data with opposite sensitivity directions through a dual tunneling magnetoresistive core current sensor; performing composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data; inputting the standard feedback current data into a pre-constructed current sensing model to obtain a current sensing output signal; based on historical experimental current sensing output signal data, performing temperature drift compensation on the current sensing output signal to obtain a high-precision current sensing output signal; based on the high-precision current sensing output signal, obtaining a non-contact broadband high-precision voltage value of the distribution network through voltage inversion; wherein the dual tunneling magnetoresistive core current sensor is the current sensor described above. The present invention performs composite offset voltage correction and temperature drift compensation on two acquired feedback current data with opposite sensitivity directions, fully considers the physical properties of the measuring device itself, and corrects the offset caused by temperature change and the offset voltage caused by the magnetic core and the circuit based on the physical properties of the current sensor itself, thereby obtaining high-precision current sensing data. After that, the high-precision current sensing output signal is input into the inversion model to obtain high-precision voltage inversion data, thereby solving the problem in the prior art that high-precision voltage inversion data cannot be obtained due to the lack of high-precision non-contact current sensing data. At the same time, the high-precision non-contact current sensing data and high-precision voltage inversion data obtained by the method provided by the present invention provide a reliable data basis for broadband disturbance analysis of distribution networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Figure 1 A schematic diagram of the structure of a dual-tunneling magnetoresistive core current sensor provided by the present invention;

[0106] Figure 2 A schematic flow chart of a method for selecting a dual-tunneling magnetoresistive core current sensor provided by the present invention;

[0107] Figure 3 A structural schematic diagram of a selection system for a dual-tunneling magnetoresistive core current sensor provided by the present invention;

[0108] Figure 4 It is a flow chart of a broadband weak current sensing method for distribution network voltage inversion according to the present invention;

[0109] Figure 5 A schematic diagram of a closed-loop magnetic balance current sensing model of tunneling magnetoresistance (TMR) provided by the present invention;

[0110] Figure 6 A schematic diagram of a tunneling magnetoresistance (TMR) temperature compensation model provided by the present invention;

[0111] Figure 7 A schematic diagram of the principle of broadband voltage inversion measurement of a distribution network based on current sensing of capacitive devices provided by the present invention;

[0112] Figure 8 A schematic diagram of an equivalent model for the broadband voltage inversion measurement of a distribution network with capacitive device current sensing provided by the present invention;

[0113] Fig. 9 A schematic diagram of the structure of a non-contact broadband weak current sensing system for distribution network voltage inversion provided by the present invention;

[0114] Fig.10 A schematic diagram of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0115] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0116] Embodiment 1:

[0117] The present invention provides a dual-tunneling magnetoresistive core current sensor, specifically Figure 1 As shown, it includes: a tunneling magnetoresistive core, a feedback coil, an open magnetic ring, a sampling resistor and a feedback conditioning circuit; it is characterized in that the open magnetic ring has an opening on a side close to the feedback conditioning circuit; the tunneling magnetoresistive core is composed of two pieces, and the two tunneling magnetoresistive cores are symmetrically arranged with the center of the opening of the open magnetic ring as the symmetry point, so as to obtain two current data with opposite sensitivity directions;

[0118] The two tunneling magnetoresistive cores are connected to one end of the feedback conditioning circuit, and the other end of the feedback conditioning circuit is connected to the feedback coil and the sampling resistor in sequence. The feedback coil is wound on the open magnetic ring, and the sampling resistor is grounded. Figure 1 Indicated as GND.

[0119] Specifically, two dual tunneling magnetoresistance (TMR) cores are connected to one end of the feedback conditioning circuit, and the other end of the feedback conditioning circuit is connected to the feedback coil and the sampling resistor in sequence. In one implementation, the feedback conditioning circuit includes a three-stage operational amplifier instrumentation amplifier and a differential summing circuit, the two tunneling magnetoresistance cores are connected to one end of the three-stage operational amplifier instrumentation amplifier, the other end of the three-stage operational amplifier instrumentation amplifier is connected to one end of the differential summing circuit, and the other end of the differential summing circuit is connected to the feedback coil. In a specific embodiment of the present invention, the three-stage operational amplifier instrumentation amplifier differential summing circuit is used as a pre-stage sampling single path to achieve dual induction current summing to offset part of the offset voltage and voltage temperature drift and enhance sensitive signals. When constructing the feedback conditioning circuit, it is necessary to first perform debugging and matching to obtain the optimal common mode rejection ratio of the differential summing circuit and the sampling circuit.

[0120] The two selected dual tunneling magnetoresistance (TMR) cores have the same performance, so that two current data with opposite sensitivity directions can be obtained. The cores are installed at the opening of the open magnetic ring through a printed circuit board (PCB). In a specific embodiment of the present invention, the two dual tunneling magnetoresistance (TMR) cores are respectively located at symmetrical positions of the core cross section, and the sensitivity directions of the two dual tunneling magnetoresistance (TMR) cores are opposite. In the present invention application, the current data obtained by the two dual tunneling magnetoresistance (TMR) cores are opposite in direction, but the offset generated by the temperature drift and the offset generated by the offset voltage in the measured current data remain unchanged. Then, in the subsequent calculation, the offset can be offset by the differential summation algorithm, thereby obtaining higher-precision current data.

[0121] Among the existing non-contact current sensing methods, the Rogowski coil is suitable for measuring large currents, the Hall current sensor is greatly affected by temperature, and the fluxgate current sensor is one of the most accurate magnetic field sensors today, but it is expensive; the tunneling magnetoresistive current sensor senses current based on the tunneling magnetoresistive effect, and has the advantages of high precision, large measurement current and frequency range, small size, and low cost. It is suitable for the current of capacitive equipment in the distribution network, but high-accuracy and high-fidelity current sensing based on tunneling magnetoresistive is still a difficulty in current research. The dual tunneling magnetoresistive core current sensor provided by the present invention can obtain two current data with opposite sensitivity directions through two tunneling magnetoresistive cores, and calculate the current data distortion problem caused by the offset caused by the temperature difference and the offset voltage through the differential summation algorithm, thereby obtaining high-fidelity current data. Compared with the prior art, the present invention takes into account the physical properties of the measuring device itself, and provides a non-contact current sensor with simple structure, high precision, small size, easy installation, low cost and high practicality.

[0122] Embodiment 2:

[0123] Based on the same inventive concept, the present invention also provides a method for selecting a dual tunneling magnetoresistive core current sensor. The specific method flow chart is as follows: Figure 2 As shown, including:

[0124] Step 21: Obtain the accuracy range of the data to be tested;

[0125] Step 22: Determine the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the broadband selection mechanism;

[0126] Step 23: Determine a dual tunneling magnetoresistive core current sensor based on the tunneling magnetoresistive core parameters;

[0127] The dual tunneling magnetoresistive core current sensor is the current sensor described in Example 1 of the present application.

[0128] The present invention mainly determines the value range of each relevant parameter of the tunneling magnetoresistive core based on the measurement accuracy range of the data to be measured, and then determines the corresponding dual tunneling magnetoresistive core current sensor according to the value range. Specifically, in step 21, the accuracy range of the data to be measured includes the upper and lower limits of the current range, the upper and lower limits of the frequency range, etc. In a specific embodiment of the present invention, the accuracy range of the data to be measured includes one or more of the following: the minimum current value of the data to be measured, the upper limit value of the frequency of the data to be measured, and the lower limit value of the frequency of the data to be measured.

[0129] Step 22, specifically, the tunneling magnetoresistive core parameters include: the resistance of the tunneling magnetoresistive core, the parasitic voltage value range, and the normalized noise spectrum density value range.

[0130] First, based on the minimum current value of the data to be tested, the minimum magnetic field value at the tunneling magnetoresistive core is simulated and calculated. In a specific embodiment provided in the present invention application, simulation software, such as CTS Studio, Multisim and other simulation software, is used to perform simulation calculations based on the current sensing model used in the test. The minimum value of the measured current range is set, and the magnetic field size B1 at the tunneling magnetoresistive core is obtained through the simulation software. Specifically, taking a measured current of 10mA as an example, the magnetic field size obtained by simulation at the core is 0.0025Oe.

[0131] For the noise analysis mechanism, the present invention analyzes by the ratio between the local noise peak and the magnetic field. The background noise usually refers to the inherent and unavoidable noise level inside the current sensor when there is no external signal input. The magnetic field is usually used to describe the strength of the magnetic field on the magnetic material or current. Calculating the ratio between the background noise peak and the magnetic field value is actually a measure of the strength of the magnetic field signal relative to the background noise of the current sensor. The smaller the ratio of the two, the higher the signal clarity or detectability. In the present invention, the physical performance of the current sensor is guaranteed to meet the standard by setting the ratio of the background noise peak to the magnetic field value to be less than the measurement accuracy of the current sensing model. In one implementation of the present invention, based on the minimum magnetic field value at the tunneling magnetoresistive core and the measurement accuracy of the current sensing model, the minimum background peak can be calculated, and then based on the minimum background peak, the upper frequency limit of the data to be measured and the lower frequency limit of the data to be measured, the minimum value of the normalized noise spectrum density of the tunneling magnetoresistive core is calculated. Finally, based on the minimum value of the normalized noise spectrum density, the parameter range that meets the requirements of the tunneling magnetoresistive core is determined, and finally the selection is performed.

[0132] Specifically, firstly, the peak value of the background noise impact of the tunnel magnetoresistive core is calculated using formula (3).

[0133]

[0134] Among them, F f is the peak value of the background noise of the tunnel magnetoresistive core, e fnorm is the normalized noise spectral density, f H is the upper limit of the measurement frequency, f L The lower limit of the measurement frequency.

[0135] In a specific embodiment of the present invention, f L Take 50Hz, f H Take 30kHz, the normalized noise spectral density e of different tunneling magnetoresistive cores fnorm The values ​​are different. Taking the tunneling magnetoresistance (TMR) chip with a noise of 10nT / rtHz@1Hz as an example, its low noise peak impact amount is 24.287nT.

[0136] The peak value E is affected by the magnetic field B1 at the core and the background noise of the tunnel magnetoresistive core. f Convert to the same unit of measurement, such as nT or Oe, then B1 and E f The following requirements should be met:

[0137]

[0138] Among them, E f is the background noise impact peak of the tunneling magnetoresistive core; B1 is the magnetic field size at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model used in the test. In a specific embodiment of the present invention, a tunneling magnetoresistive (TMR) closed-loop magnetic balance current sensing model is used. Through the above noise analysis mechanism, the normalized noise spectrum density value range of the tunneling magnetoresistive core is obtained by formula (4).

[0139] In a specific embodiment of the present invention, the values ​​of the parameters are: B1 = 0.0025Oe = 250nT, the measurement accuracy of the S1 current sensing model is 1%, then E f The peak value of the background noise impact cannot exceed 2.5nT, and the normalized noise spectrum density e of the tunnel magnetoresistive core is required to be fnorm The value shall not exceed 1nT / rtHz@1Hz.

[0140] Afterwards, based on the upper frequency limit value of the data to be measured, the resistance and parasitic voltage value ranges of the tunneling magnetoresistive core are calculated through a wideband selection mechanism; similarly, based on the wideband selection mechanism proposed in the present invention, knowing the physical performance parameters of the tunneling magnetoresistive core, it is possible to calculate the bandwidth range that the tunneling magnetoresistive core can measure, and then calculate the corresponding bandwidth range for tunneling magnetoresistive cores of different models, and it is also possible to select a tunneling magnetoresistive core that meets the requirements according to the required measurement bandwidth range.

[0141] Specifically, the broadband selection mechanism mainly uses the resistance and parasitic capacitance of the tunneling magnetoresistive core for calculation. Considering the limitations of the circuit and the device itself on the frequency range, the physical performance of the broadband weak current sensing module is defined to satisfy the following formula:

[0142]

[0143] Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H The upper limit of the measurement frequency.

[0144] In a specific embodiment of the present invention, f H30kHz is taken to ensure the measurement bandwidth of the wide-band weak current sensor, and K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor.

[0145] The present invention introduces noise analysis and broadband selection mechanism, based on the peak calculation of the core background noise and the tunneling magnetoresistance core selection technology based on the physical characteristics of the core, to ensure the accuracy of broadband weak current perception and a wide measurement frequency range, which can effectively improve the performance of the test device at the physical level, thereby improving the accuracy of the measurement data. The prior art does not consider the impact level that the higher the accuracy of the data to be measured, the greater the impact of the physical properties of the device on the test accuracy. The present invention provides a current sensor selection method through a noise analysis mechanism and a broadband selection mechanism, which has a driving effect on the work of obtaining high-precision measurement data for the test device.

[0146] Embodiment 3:

[0147] Based on the same inventive concept, the present invention also proposes a selection system for a dual tunneling magnetoresistive core current sensor, the structure of which is as follows: Figure 3 As shown, including:

[0148] Data acquisition module: used to obtain the accuracy range of the data to be tested;

[0149] Parameter determination module: used to determine the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the wide-band selection mechanism;

[0150] A current sensor selection module: used to determine a dual tunneling magnetoresistive core current sensor based on the tunneling magnetoresistive core parameters;

[0151] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0152] Preferably, the tunneling magnetoresistive core parameters include: resistance of the tunneling magnetoresistive core, a parasitic voltage value range, and a normalized noise spectrum density value range.

[0153] Preferably, the accuracy range of the data to be measured includes: a minimum current value of the data to be measured, an upper frequency limit value of the data to be measured, and a lower frequency limit value of the data to be measured;

[0154] The parameter determination module comprises:

[0155] A simulation calculation submodule: used to simulate and calculate the minimum magnetic field value at the tunneling magnetoresistive core using simulation software based on the minimum current value of the data to be measured;

[0156] Noise analysis submodule: used to calculate the normalized noise spectrum density value range of the tunneling magnetoresistive core through a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured;

[0157] Broadband selection mechanism submodule: used to calculate the resistance and parasitic voltage value range of the tunneling magnetoresistive core through a broadband selection mechanism based on the upper frequency limit of the data to be measured.

[0158] Preferably, the noise analysis submodule includes:

[0159] A background noise peak value calculation unit: specifically used to calculate the background noise peak value of the tunneling magnetoresistive core based on the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured;

[0160] Normalized noise spectrum density calculation unit: specifically used to obtain the value range of the normalized noise spectrum density of the tunneling magnetoresistive core by adopting a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core and the background noise peak value of the tunneling magnetoresistive core.

[0161] Preferably, the noise analysis mechanism is expressed as follows:

[0162]

[0163] Among them, E f The peak value of the background noise of the tunnel magnetoresistive core is affected; e fnorm is the normalized noise spectrum density of the tunneling magnetoresistive core; f H is the upper limit of the frequency of the data to be tested; f L is the lower limit of the frequency of the data to be measured; B1 is the minimum magnetic field value at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model;

[0164] The broadband selection mechanism is expressed as follows:

[0165]

[0166] Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H is the upper limit of the frequency of the data to be tested.

[0167] The present invention provides a selection system for a dual tunneling magnetoresistive core current sensor. Based on the peak value calculation of the core background noise and the tunneling magnetoresistive (TMR) core selection technology based on the physical characteristics of the core, simulation software can be used to obtain the parameter value range of the tunneling magnetoresistive (TMR) core for wide-band weak current sensing that meets the measurement accuracy, thereby providing a selection system based on the physical characteristics of the core, which can effectively improve the measurement accuracy of the dual tunneling magnetoresistive core current sensor.

[0168] Embodiment 4:

[0169] Based on the same inventive concept, the present invention also provides a broadband weak current sensing method for distribution network voltage inversion. The specific method flow chart is as follows: Figure 4 As shown, including:

[0170] Step 41: Processing the feedback current into two current data with opposite sensitivity directions through a dual tunneling magnetoresistive core current sensor;

[0171] Step 42: performing composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data;

[0172] Step 43: inputting the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal;

[0173] Step 44: Based on historical experimental current sensing output signal data, temperature drift compensation is performed on the current sensing output signal to obtain a high-precision current sensing output signal;

[0174] Step 45: Based on the high-precision current sensing output signal, a distribution network contactless broadband high-precision voltage value is obtained by voltage inversion;

[0175] Wherein, the dual tunneling magnetoresistive core current sensor is any one of the current sensors mentioned above.

[0176] Before step 41, a tunneling magnetoresistance (TMR) closed-loop magnetic balance current sensing model is first constructed. For high-precision broadband weak current sensing, the basic working principle is: based on the closed-loop magnetic balance structure, the measured current passes through the center of the magnetic flux collection coil and generates a magnetic field at the air gap; a feedback coil is introduced, and the feedback current is adjusted by measuring the small magnetic field changes generated by the measured current so that the magnetic field at the tunneling magnetoresistance core reaches equilibrium, and then the magnitude of the measured current is calculated by measuring the magnitude of the feedback current.

[0177] The tunneling magnetoresistance (TMR) closed-loop magnetic balance current sensing model constructed by the present invention is as follows: Figure 5As shown, it specifically includes: a magnetic field information acquisition unit based on a tunneling magnetoresistive core, a signal processing unit, a sampling feedback unit, an out-of-loop adjustment unit, and a signal output unit. The overall design is based on the idea of ​​developing a closed-loop structure based on tunneling magnetoresistance. The feedback current is adjusted by adjusting the closed-loop feedback unit until the magnetic field at the tunneling magnetoresistive core reaches equilibrium. The feedback current data at this time is collected by the tunneling magnetoresistive (TMR) magnetic field acquisition unit. After the feedback current data passes through the signal processing unit and the out-of-loop adjustment unit, the current sensing output signal is output. Among them, the magnetic field information acquisition unit based on the tunneling magnetoresistive core, in a specific embodiment of the present invention, is any of the aforementioned dual tunneling magnetoresistive core current sensors, and the feedback current is processed into two current data with opposite sensitivity directions, which are used for subsequent temperature drift correction and offset voltage correction to obtain high-precision standard feedback current data.

[0178] Step 41, specifically, the feedback current is processed into two current data with opposite sensitivity directions through the dual tunneling magnetoresistive core current sensor. In this set of current data with opposite sensitivity directions, the direction of the current offset remains unchanged, but the current direction is opposite. The deviation caused by the measuring device itself can be eliminated through differential summation calculation, thereby achieving the technical effect of improving data accuracy.

[0179] Step 42, specifically, based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, a composite offset voltage correction is performed on the current data with two opposite sensitivity directions. The composite offset voltage correction is mainly divided into two parts. The first aspect is to perform voltage correction on the offset caused by the tunneling magnetoresistive core. After that, the second part is to perform voltage correction on the offset caused by the conditioning feedback circuit through a differential summation algorithm, thereby obtaining high-precision standard feedback current data. Specifically, in the present invention, an analog zeroing module can be used to balance the offset voltage using a level, and the level provided by a potentiometer can be used. The offset voltage range can be calculated to obtain the maximum value through the specification.

[0180] In a specific embodiment of the present disclosure, if the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor is a bridge tunneling magnetoresistive (TMR) core, the offset voltage can be calculated by referring to the specification sheet, and the calculation formula is as follows:

[0181]

[0182] Among them, U is the offset voltage of the bridge tunnel magnetoresistance (TMR) core, R1, R2, R3 and R4 are the resistance values ​​of the four resistors in the bridge tunnel magnetoresistance (TMR) core, and V is the voltage across the bridge tunnel magnetoresistance (TMR) core. Afterwards, according to the offset voltage calculated above, the core offset voltage correction is performed on the two current data with opposite sensitivity directions.

[0183] Specifically, the second part corrects the offset caused by the conditioning feedback circuit, and according to the dual core summing temperature drift compensation mechanism, based on the current data in the two sensitivity directions after the correction, the circuit offset voltage is corrected through the differential summation algorithm to obtain standard feedback current data. In this process, the current data in the two sensitivity directions after the core correction has already corrected the voltage offset caused by the core, as well as the voltage offset caused by the feedback conditioning circuit and the temperature offset caused by the temperature. These current offsets have always existed in the acquired current data and will not change direction due to changes in the current direction. Therefore, by performing differential summation calculations on the current data in the two sensitivity directions after the correction, part of the offset voltage and voltage temperature drift can be offset, the sensitive signal can be enhanced, and the accuracy of the acquired current data can be improved, and finally the standard feedback current data can be obtained.

[0184] The present invention performs composite offset voltage correction on two current data with opposite sensitivity directions, thereby eliminating some offsets caused by the current sensor itself and improving the accuracy of the acquired current data.

[0185] Step 43, specifically, input the standard feedback current data into a pre-constructed current sensing model to obtain a current sensing output signal. Wherein, the current sensing model is a mathematical model constructed based on the physical properties of the tunneling magnetoresistance (TMR) closed-loop magnetic balance current sensing model constructed in step 41, and the current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual tunneling magnetoresistance core current sensor, combined with the output characteristics of the circuit designed in the dual tunneling magnetoresistance core current sensor. In the present invention, based on the current data corrected by the composite offset voltage, a current sensing output signal is obtained through the current sensing model. Wherein, the output signal includes: a current output signal and a voltage output signal.

[0186] If the current signal is used as the output, I1 is marked as the measured current, and I2 is the current output signal, then the relationship between the two is:

[0187]

[0188] Among them, I1 is the measured current; I2 is the current output signal; R0 is the sum of the coil resistance of the closed-loop magnetic balance structure, the sampling resistance and the stray resistance, S is the sensitivity of the dual tunneling magnetoresistive core, K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the current sensor of the dual tunneling magnetoresistive core; σ is the measurement error.

[0189] If the voltage signal is used as the output, I1 is marked as the measured current, V1 is the closed-loop output voltage, V2 is the voltage output signal, and the relationship between V2 and I1 is:

[0190] V2=K2V1=K2I3R0

[0191] I1=NI3+σ (2)

[0192] Among them, V1 is the closed-loop output voltage; V2 is the voltage output signal; R0 is the sum of the sampling resistor and the stray resistance in the current sensing model, K2 is the circuit gain of the out-of-loop adjustment unit, I1 is the measured current; I3 is the standard feedback current data, N is the number of turns of the feedback coil, and σ is the measurement error. Among them, σ, according to the broadband voltage sensing requirements of the distribution network, can be 1%-1.5%, that is, the value range of σ is 0.01*I2 to 0.015*I2; the number of turns N, the circuit gain K1 and K2 affect the final output ratio. Generally, the three values ​​are comprehensively considered. In this specific embodiment, the output voltage corresponding to the measured current of 10mA is 1V to meet the output ratio of 1:100, and it can also be adjusted to other ratios.

[0193] Step 44 specifically includes: determining a number of experimental output signal values ​​and a standard output signal value at the current temperature based on the current temperature value; calculating an average value of a number of differences between the experimental output signal value and the standard output signal value based on the number of experimental output signal values ​​and the standard output signal value at the current temperature; determining a corresponding temperature drift correction factor at the current temperature based on the average value; and performing temperature drift compensation on the current sensing output signal based on the corresponding temperature drift correction factor at the current temperature to obtain a high-precision current sensing output signal.

[0194] To set the correction value between a specific temperature and a specific measurement value:

[0195] C i,j =[T i ,Z j ]

[0196] Among them, C i,j Indicates the correction factor for the current temperature and measured value, T i Indicates temperature, Z j Indicates the measured value.

[0197] In a specific embodiment of the present invention, digital compensation can be performed for the correction of temperature drift by using a table lookup method. A lookup table is established based on empirical data. The relationship between temperature change and output of the tunneling magnetoresistance (TMR) current sensor is collected in large quantities based on experimental data. The tunneling magnetoresistance (TMR) current sensor is tested in large quantities to obtain the average offset value at the temperature and measured value. Taking the room temperature of 25 degrees as the benchmark, a small amount of offset will occur in the measured value at different temperatures, and then the correction factor is determined.

[0198] In a specific embodiment provided by the present invention, temperature drift compensation and offset voltage correction can be achieved by the following temperature compensation model, such as Figure 6 As shown in the figure, the temperature compensation model mainly includes: TMR magnetic field acquisition unit, differential amplifier, summing circuit, analog zero adjustment module, temperature sensor, digital compensation module and output module. Among them, the analog zero adjustment module is used to correct the offset voltage, the digital compensation module is used to correct the temperature drift, and finally the high-precision induction current output data is calculated in the summing circuit and outputted.

[0199] After the current sensing output signal is compensated for temperature drift by the correction factor, a high-precision current sensing output signal is obtained. Through step 44, the correction of the sensing current data is completed, and the measured feedback data is corrected from two aspects: offset voltage and temperature drift. Compared with the prior art that does not consider the influence of these two aspects, the physical properties of the measuring device itself are fully considered, and the offset caused by temperature change and the offset voltage caused by the magnetic core and circuit are corrected based on the physical properties of the current sensor itself, which can effectively improve the accuracy of the measurement data.

[0200] Step 45, specifically, based on the high-precision current sensing output signal, voltage inversion is performed through a distribution network broadband voltage inversion model based on current sensing of capacitive devices to obtain a distribution network contactless broadband high-precision voltage value. Figure 7 As shown in the figure, it is a distribution network broadband voltage inversion measurement principle based on capacitive device current sensing. Through the tunneling magnetoresistance (TMR) broadband weak current sensing module, the induced current data is obtained, and the broadband voltage output is finally obtained through digital inversion and analog inversion. Figure 7 middle Represents the electric field strength in space, represents the leakage current of the capacitor device, B represents the magnetic field generated by the leakage current, Represents the impedance of a capacitive device.

[0201] Among them, the distribution network broadband voltage inversion model based on capacitive device current sensing is to convert the capacitive device into an RC circuit model with several branches, such as Figure 8 As shown, the capacitive devices are equivalent to: capacitor C1 and resistor R1, capacitor C2 and resistor R2, capacitor C n With resistor R n The circuit model of multiple branches formed in series. At the same time, the construction of the model also takes into account the polarization characteristics, where R0 is the lossy polarization equivalent impedance of several branches of capacitive equipment, C0 is the number of capacitive equipment, U is the voltage across the capacitive equipment of the distribution network, and I is the current.

[0202] Specifically, the broadband voltage inversion model of the distribution network based on current sensing of capacitive devices constructed by the present invention uses the tunneling magnetoresistance (TMR) current sensing output as the input of the inversion model to invert the broadband voltage information of the distribution network. The expression of the broadband voltage inversion model of the distribution network based on current sensing of capacitive devices is as follows, which represents the physical relationship between the voltage U across the capacitive device and the total current I flowing through the capacitive device:

[0203]

[0204] Among them, U is the voltage across the capacitive device of the distribution network; I is the high-precision current data; R is the equivalent impedance of the capacitive device; C is the equivalent geometric capacitance of the capacitive device; R0 is the lossy polarization equivalent impedance of several branches of the capacitive device; C0 is the lossy polarization equivalent geometric capacitance of several branches of the capacitive device; j is an imaginary unit; ω is the angular velocity.

[0205] Specifically, in a specific embodiment of the present invention, the number of model branches is related to the measurement frequency range, and the number of saturated branches can be obtained by fitting through a fitting method. The model can be implemented through algorithm-based digital inversion or circuit-based simulation.

[0206] Table 1 shows the test results of the broadband weak current sensor.

[0207]

[0208]

[0209] Table 1

[0210] The load types of the distribution network are complex, the power quality is poor, and the harmonic and higher harmonic content is much higher than that of the high-voltage power grid. Among the existing non-contact current sensing methods, the Rogowski coil is suitable for measuring large currents, the Hall current sensor is greatly affected by temperature, and the fluxgate current sensor is one of the most accurate magnetic field sensors today, but it is expensive; the tunneling magnetoresistive current sensor senses current based on the tunneling magnetoresistive effect, and has the advantages of high accuracy, large measurement current and frequency range, small size, and low cost. It is suitable for the inverse measurement of current to voltage of capacitive equipment in the distribution network. Among the existing voltage sensing methods, the electromagnetic voltage transformer has a small dynamic range and large high-frequency measurement errors; the resistor and capacitor voltage divider needs to be connected to the primary equipment loop, and the installation and deployment are complicated; the measurement accuracy of the piezoelectric electric field sensor and the electro-optical electric field sensor is easily affected by the deployment location and environment. Through non-contact sensing of the grounding current of capacitive equipment and the wide-band current-voltage inversion mechanism, indirect measurement from voltage to current and then to distribution network voltage can be achieved to obtain wide-band voltage characteristics. It has outstanding advantages such as no change in primary wiring and high safety. It is a new and efficient wide-band voltage sensing method. However, this method is based on accurate and efficient non-contact current sensing. The grounding current of capacitive equipment in the distribution network is generally referred to as milliampere level, requiring a frequency measurement range of up to 30kHz, and safety and reliability issues need to be considered at the same time.

[0211] In view of the problems existing in the above-mentioned prior art, the present invention proposes a non-contact broadband weak current sensing method based on tunneling magnetoresistance to provide accurate current parameters for broadband voltage inversion. The non-contact broadband weak current sensing method is based on the closed-loop structure design based on tunneling magnetoresistance, and introduces noise analysis and broadband selection mechanism to screen the physical properties of the dual tunneling magnetoresistance core, thereby ensuring broadband and sensing accuracy. After that, the offset voltage and temperature drift are adjusted and compensated based on the dual core summation temperature drift compensation mechanism to ensure measurement accuracy, which can provide non-contact, high-precision, broadband current sensing signals for broadband voltage inversion of distribution network. In addition, it also has technical characteristics such as small size, easy installation and low cost. Finally, the present invention considers the practical difficulties of broadband voltage sensing in distribution network application, takes broadband weak current sensing of capacitive equipment in distribution network as a premise, proposes an equivalent physical model of capacitive equipment, gives the current-voltage inversion relationship, and obtains broadband (10kHz) voltage information, providing a basis for broadband disturbance analysis of distribution network.

[0212] Embodiment 5:

[0213] Based on the same inventive concept, the present invention also proposes a broadband weak current sensing system for distribution network voltage inversion. The system structure is as follows: Fig. 9 As shown, including:

[0214] Feedback current acquisition module: used to process the feedback current into two current data with opposite sensitivity directions through a dual tunneling magnetoresistive core current sensor;

[0215] Composite offset voltage correction module: used to perform composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data;

[0216] Current sensing module: used to input the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal;

[0217] Temperature drift compensation module: used to perform temperature drift compensation on the current sensing output signal based on historical experimental current sensing output signal data to obtain a high-precision current sensing output signal;

[0218] Voltage inversion module: used to obtain a non-contact broadband high-precision voltage value of the distribution network through voltage inversion based on the high-precision current sensing output signal;

[0219] Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor as described above.

[0220] Preferably, the composite offset voltage correction module includes:

[0221] A core offset voltage correction submodule: used to perform core offset voltage correction on the current data in the two sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, so as to obtain corrected current data in the two sensitivity directions;

[0222] Circuit offset voltage correction submodule: used to perform circuit offset voltage correction based on the corrected current data in the two sensitivity directions through a differential summation algorithm to obtain standard feedback current data.

[0223] Preferably, the magnetic core offset voltage correction submodule includes:

[0224] A core offset voltage estimation unit: used to estimate the offset voltage value of the tunneling magnetoresistive core based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor and according to the offset voltage calculation formula corresponding to the tunneling magnetoresistive core;

[0225] A core voltage correction unit is used to perform core offset voltage correction on the current data in the two sensitivity directions according to the offset voltage value of the tunnel magnetoresistive core, so as to obtain corrected current data in the two sensitivity directions.

[0226] Preferably, the historical experimental current sensing output signal data includes: a number of experimental output signal values ​​and output signal standard values;

[0227] The temperature drift compensation module comprises:

[0228] Standard value determination unit: used to determine several experimental output signal values ​​and standard output signal values ​​at the current temperature based on the current temperature value;

[0229] A difference calculation unit is used to calculate an average value of a plurality of differences between the experimental output signal value and the standard output signal value based on a plurality of experimental output signal values ​​and a standard output signal value at the current temperature;

[0230] A temperature drift correction factor determination unit: used to determine a temperature drift correction factor corresponding to the current temperature based on the average value;

[0231] A temperature drift correction unit is used to perform temperature drift compensation on the current sensing output signal based on the corresponding temperature drift correction factor at the current temperature to obtain a high-precision current sensing output signal.

[0232] Preferably, the current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual-tunneling magnetoresistive core current sensor, combined with the output characteristics of the designed circuit in the dual-tunneling magnetoresistive core current sensor.

[0233] Preferably, the designed circuit output characteristics include: a circuit gain of a signal processing unit and a circuit gain of an out-of-loop adjustment unit; the current sensing output signal includes: a current output signal and a voltage output signal;

[0234] The expression of the current sensing model is as follows:

[0235]

[0236] V2=K2V1=K2I3R0

[0237] I1=NI3+σ

[0238] Among them, I3 is the standard feedback current data; I1 is the measured current; I2 is the current output signal; S is the sensitivity of the dual tunneling magnetoresistive core current sensor; K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the dual tunneling magnetoresistive core current sensor; R0 is the resistance of the dual tunneling magnetoresistive core current sensor; V1 is the closed-loop output voltage; V2 is the voltage output voltage; σ is the measurement error.

[0239] The present invention provides a non-contact, broadband, weak current sensing system for distribution network voltage inversion. The system performs composite offset voltage correction and temperature drift compensation on two feedback current data with opposite sensitivity directions, fully considers the physical properties of the measuring device itself, corrects the offset caused by temperature change and the offset voltage caused by a magnetic core and a circuit based on the physical properties of the current sensor itself, obtains high-precision induced current data, and then performs voltage inversion based on the high-precision current data to further obtain high-precision voltage information, thereby providing a sensing system for high-precision voltage inversion data.

[0240] Example 6

[0241] like Fig.10 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0242] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or a corresponding function, so as to implement a selection method of a dual-tunneling magnetoresistive core current sensor in the above-mentioned embodiment, or a step of a broadband weak current sensing method for distribution network voltage inversion.

[0243] Example 7

[0244] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in electronic devices and, of course, extended storage media supported by electronic devices. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage. The processor loads and executes one or more instructions stored in the storage medium, which can realize a selection method of a dual tunneling magnetoresistive core current sensor in the above embodiment, or a step of a broadband weak current sensing method for distribution network voltage inversion.

[0245] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0246] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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 generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0247] These computer program instructions may also be stored in a computer-readable memory capable of directing 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 an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0248] 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, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0249] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A dual tunneling magnetoresistive core current sensor comprising: A tunneling magnetoresistive core, a feedback coil, an open magnetic ring, a sampling resistor and a feedback conditioning circuit; characterized in that the open magnetic ring has an opening on a side close to the feedback conditioning circuit; the tunneling magnetoresistive core is composed of two pieces, and the two pieces of tunneling magnetoresistive cores are symmetrically arranged with the center of the opening of the open magnetic ring as the symmetry point, so as to obtain two current data with opposite sensitivity directions; The two tunneling magnetoresistive cores are connected to one end of the feedback conditioning circuit, the other end of the feedback conditioning circuit is connected to the feedback coil and the sampling resistor in sequence, the feedback coil is wound on the open magnetic ring, and the sampling resistor is grounded.

2. The current sensor according to claim 1, characterized in that: The feedback conditioning circuit includes a three-stage operational amplifier instrumentation amplifier and a differential summing circuit, the two tunneling magnetoresistive cores are connected to one end of the three-stage operational amplifier instrumentation amplifier, the other end of the three-stage operational amplifier instrumentation amplifier is connected to one end of the differential summing circuit, and the other end of the differential summing circuit is connected to the feedback coil.

3. A method for selecting a dual tunneling magnetoresistive core current sensor, characterized in that: include: Get the accuracy range of the data to be tested; Based on the passing noise analysis mechanism and the wideband selection mechanism, determining the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured; Based on the tunneling magnetoresistive core parameters, determining a dual tunneling magnetoresistive core current sensor; Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor described in claims 1-2.

4. The method according to claim 3, characterized in that The tunneling magnetoresistive core parameters include: the resistance of the tunneling magnetoresistive core, the parasitic voltage value range and the normalized noise spectrum density value range.

5. The method according to claim 4, characterized in that The accuracy range of the data to be measured includes: the minimum current value of the data to be measured, the upper frequency limit value of the data to be measured, and the lower frequency limit value of the data to be measured; the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the wideband selection mechanism include: Based on the minimum current value of the data to be measured, the minimum magnetic field value at the tunneling magnetoresistive core is simulated and calculated using simulation software; Based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured, the normalized noise spectrum density value range of the tunneling magnetoresistive core is calculated through a noise analysis mechanism; Based on the upper frequency limit of the data to be measured, the resistance and parasitic voltage value ranges of the tunneling magnetoresistive core are calculated through a wide-band selection mechanism.

6. The method according to claim 5, characterized in that The calculation of the normalized noise spectrum density value range of the tunneling magnetoresistive core based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured, and the lower frequency limit value of the data to be measured by a noise analysis mechanism includes: Calculating the background noise peak value of the tunneling magnetoresistive core based on the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured; Based on the minimum magnetic field value at the tunneling magnetoresistive core and the background noise peak value of the tunneling magnetoresistive core, a noise analysis mechanism is adopted to obtain a value range of a normalized noise spectrum density of the tunneling magnetoresistive core.

7. The method according to claim 6, characterized in that The noise analysis mechanism is expressed as follows: Among them, E f The peak value of the background noise of the tunnel magnetoresistive core is affected; e fnorm is the normalized noise spectrum density of the tunneling magnetoresistive core; f H is the upper limit of the frequency of the data to be tested; f L is the lower limit of the frequency of the data to be measured; B1 is the minimum magnetic field value at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model; The broadband selection mechanism is expressed as follows: Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H is the upper limit of the frequency of the data to be tested.

8. A selection system for a dual tunneling magnetoresistive core current sensor, characterized in that: include: Data acquisition module: used to obtain the accuracy range of the data to be tested; Parameter determination module: used to determine the tunneling magnetoresistive core parameters that meet the accuracy range of the data to be measured based on the passing noise analysis mechanism and the wide-band selection mechanism; A current sensor selection module: used to determine a dual tunneling magnetoresistive core current sensor based on the tunneling magnetoresistive core parameters; Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor described in claims 1-2.

9. The system according to claim 8, characterized in that The tunneling magnetoresistive core parameters include: the resistance of the tunneling magnetoresistive core, the parasitic voltage value range and the normalized noise spectrum density value range.

10. The system according to claim 9, characterized in that The accuracy range of the data to be measured includes: the minimum current value of the data to be measured, the upper frequency limit value of the data to be measured, and the lower frequency limit value of the data to be measured; The parameter determination module comprises: A simulation calculation submodule: used to simulate and calculate the minimum magnetic field value at the tunneling magnetoresistive core using simulation software based on the minimum current value of the data to be measured; Noise analysis submodule: used to calculate the normalized noise spectrum density value range of the tunneling magnetoresistive core through a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core, the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured; Broadband selection mechanism submodule: used to calculate the resistance and parasitic voltage value range of the tunneling magnetoresistive core through a broadband selection mechanism based on the upper frequency limit of the data to be measured.

11. The system according to claim 10, characterized in that The noise analysis submodule includes: A background noise peak value calculation unit: specifically used to calculate the background noise peak value of the tunneling magnetoresistive core based on the upper frequency limit value of the data to be measured and the lower frequency limit value of the data to be measured; Normalized noise spectrum density calculation unit: specifically used to obtain the value range of the normalized noise spectrum density of the tunneling magnetoresistive core by adopting a noise analysis mechanism based on the minimum magnetic field value at the tunneling magnetoresistive core and the background noise peak value of the tunneling magnetoresistive core.

12. The system according to claim 8, characterized in that The noise analysis mechanism is expressed as follows: Among them, E f The peak value of the background noise of the tunnel magnetoresistive core is affected; e fnorm is the normalized noise spectrum density of the tunneling magnetoresistive core; f H is the upper limit of the frequency of the data to be tested; f L is the lower limit of the frequency of the data to be measured; B1 is the minimum magnetic field value at the tunneling magnetoresistive core; S1 is the measurement accuracy of the current sensing model; The broadband selection mechanism is expressed as follows: Where K is the gain factor of the first-order low-pass filter of the dual tunneling magnetoresistive core current sensor, R MTJ is the resistance of the tunneling magnetoresistive core, C TMR is the parasitic capacitance of the tunneling magnetoresistive core, f H is the upper limit of the frequency of the data to be tested.

13. A broadband weak current sensing method for distribution network voltage inversion, characterized in that: include: The feedback current is processed into two current data with opposite sensitivity directions through a dual tunnel magnetoresistive core current sensor; According to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, a composite offset voltage correction is performed on the two current data with opposite sensitivity directions to obtain standard feedback current data; Inputting the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal; Based on historical experimental current sensing output signal data, temperature drift compensation is performed on the current sensing output signal to obtain a high-precision current sensing output signal; Based on the high-precision current sensing output signal, a non-contact wideband high-precision voltage value of the distribution network is obtained through voltage inversion; Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor described in claims 1-2.

14. The method according to claim 13, characterized in that The method of performing composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data includes: According to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, the current data in the two sensitivity directions are corrected for the core offset voltage to obtain the corrected current data in the two sensitivity directions; Based on the corrected current data in the two sensitivity directions, a circuit offset voltage correction is performed through a differential summation algorithm to obtain standard feedback current data.

15. The method according to claim 14, characterized in that According to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, the current data in the two sensitivity directions are corrected for the core offset voltage to obtain the corrected current data in the two sensitivity directions, including: Based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, and according to the offset voltage calculation formula corresponding to the tunneling magnetoresistive core, estimating the offset voltage value of the tunneling magnetoresistive core; According to the offset voltage value of the tunnel magnetoresistive core, the current data in the two sensitivity directions are corrected for the core offset voltage to obtain the corrected current data in the two sensitivity directions.

16. The method according to claim 15, characterized in that The historical experimental current sensing output signal data includes: a plurality of experimental output signal values ​​and output signal standard values; based on the historical experimental current sensing output signal data, the current sensing output signal is subjected to temperature drift compensation to obtain a high-precision current sensing output signal, including: Based on the current temperature value, determine several experimental output signal values ​​and standard output signal values ​​at the current temperature; Based on a plurality of experimental output signal values ​​and a standard output signal value at the current temperature, calculating an average value of a plurality of differences between the experimental output signal value and the standard output signal value; Determine a temperature drift correction factor corresponding to the current temperature based on the average value; Based on the temperature drift correction factor corresponding to the current temperature, the temperature drift compensation is performed on the current sensing output signal to obtain a high-precision current sensing output signal.

17. The method according to any one of claims 13 to 16, characterized in that: The current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual-tunneling magnetoresistive core current sensor, combined with the output characteristics of the designed circuit in the dual-tunneling magnetoresistive core current sensor.

18. The method according to claim 17, characterized in that The designed circuit output characteristics include: the circuit gain of the signal processing unit and the circuit gain of the out-of-loop adjustment unit; the current sensing output signal includes: a current output signal and a voltage output signal; The expression of the current sensing model is as follows: V2=K2V1=K2I3R0 I1=NI3+σ Among them, I3 is the standard feedback current data; I1 is the measured current; I2 is the current output signal; S is the sensitivity of the dual tunneling magnetoresistive core current sensor; K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the dual tunneling magnetoresistive core current sensor; R0 is the resistance of the dual tunneling magnetoresistive core current sensor; V1 is the closed-loop output voltage; V2 is the voltage output voltage; σ is the measurement error.

19. A broadband weak current sensing system for distribution network voltage inversion, characterized in that: include: Feedback current acquisition module: used to process the feedback current into two current data with opposite sensitivity directions through a dual tunneling magnetoresistive core current sensor; Composite offset voltage correction module: used to perform composite offset voltage correction on the two current data with opposite sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor to obtain standard feedback current data; Current sensing module: used to input the standard feedback current data into a pre-built current sensing model to obtain a current sensing output signal; Temperature drift compensation module: used to perform temperature drift compensation on the current sensing output signal based on historical experimental current sensing output signal data to obtain a high-precision current sensing output signal; Voltage inversion module: used to obtain a non-contact broadband high-precision voltage value of the distribution network through voltage inversion based on the high-precision current sensing output signal; Wherein, the dual tunneling magnetoresistive core current sensor is the current sensor described in claims 1-2.

20. The system according to claim 19, characterized in that The composite offset voltage correction module comprises: A core offset voltage correction submodule: used to perform core offset voltage correction on the current data in the two sensitivity directions according to the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor, so as to obtain corrected current data in the two sensitivity directions; Circuit offset voltage correction submodule: used to perform circuit offset voltage correction based on the corrected current data in the two sensitivity directions through a differential summation algorithm to obtain standard feedback current data.

21. The system according to claim 20, characterized in that The core offset voltage correction submodule comprises: A core offset voltage estimation unit: used to estimate the offset voltage value of the tunneling magnetoresistive core based on the equivalent circuit structure and resistance value of the tunneling magnetoresistive core in the dual tunneling magnetoresistive core current sensor and according to the offset voltage calculation formula corresponding to the tunneling magnetoresistive core; A core voltage correction unit is used to perform core offset voltage correction on the current data in the two sensitivity directions according to the offset voltage value of the tunnel magnetoresistive core, so as to obtain corrected current data in the two sensitivity directions.

22. The system according to claim 19, characterized in that The historical experimental current sensing output signal data includes: a number of experimental output signal values ​​and output signal standard values; The temperature drift compensation module comprises: Standard value determination unit: used to determine several experimental output signal values ​​and standard output signal values ​​at the current temperature based on the current temperature value; A difference calculation unit is used to calculate an average value of a plurality of differences between the experimental output signal value and the standard output signal value based on a plurality of experimental output signal values ​​and a standard output signal value at the current temperature; A temperature drift correction factor determination unit: used to determine a temperature drift correction factor corresponding to the current temperature based on the average value; A temperature drift correction unit is used to perform temperature drift compensation on the current sensing output signal based on the corresponding temperature drift correction factor at the current temperature to obtain a high-precision current sensing output signal.

23. The system according to claims 19-22, characterized in that The current sensing model is constructed based on the sensitivity, feedback coil and resistance of the dual-tunneling magnetoresistive core current sensor, combined with the output characteristics of the designed circuit in the dual-tunneling magnetoresistive core current sensor.

24. The system according to claim 23, characterized in that The designed circuit output characteristics include: the circuit gain of the signal processing unit and the circuit gain of the out-of-loop adjustment unit; the current sensing output signal includes: a current output signal and a voltage output signal; The expression of the current sensing model is as follows: V2=K2V1=K2I3R0 I1=NI3+σ Among them, I3 is the standard feedback current data; I1 is the measured current; I2 is the current output signal; S is the sensitivity of the dual tunneling magnetoresistive core current sensor; K1 is the circuit gain of the signal processing unit; K2 is the circuit gain of the out-of-loop adjustment unit; N is the number of turns of the feedback coil of the dual tunneling magnetoresistive core current sensor; R0 is the resistance of the dual tunneling magnetoresistive core current sensor; V1 is the closed-loop output voltage; V2 is the voltage output voltage; σ is the measurement error.

25. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a method for selecting a dual-tunneling magnetoresistive core current sensor as described in any one of claims 3 to 7, or a wide-band weak current sensing method for distribution network voltage inversion as described in any one of claims 8 to 13 is implemented.

26. A readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a selection method for a dual-tunneling magnetoresistive core current sensor as described in any one of claims 3 to 7, or a wide-band weak current sensing method for distribution network voltage inversion as described in any one of claims 8 to 13 is implemented.

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