CN116643077A - TMR current detection device and detection method based on standard magnetic source - Google Patents
TMR current detection device and detection method based on standard magnetic source Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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Abstract
The application discloses a TMR current detection device based on a standard magnetic source, which belongs to the field of detection and protection of power systems, and comprises: the device comprises a magnetic focusing ring with an air gap, a standard magnetic source, a first magnetic induction chip, a second magnetic induction chip, a data processing unit, a reference current generating module and a signal processing module, wherein the reference current generating module comprises a reference waveform generator, a conditioning circuit and a power amplifying circuit, and the signal processing module comprises a first differential amplifying circuit, a high-pass filter circuit and a second differential circuit. The current detection device has the effects of high precision and low cost. Meanwhile, a current detection method is also provided, and the method has strong external interference resistance and is little influenced by hysteresis.
Description
Technical Field
The application belongs to the field of detection and protection of power systems, and particularly relates to a TMR current detection device and method based on a standard magnetic source.
Background
In the operation and maintenance process of the smart grid, a series of currents need to be monitored in real time. The coverage range of the monitoring scene is wide, the amplitude of the current to be measured ranges from tens of mu A to hundreds of kA, the frequency covers direct current and power frequency to hundreds of kHz, and the traditional current transformer is difficult to realize accurate measurement. Therefore, in order to achieve accurate monitoring of the current, a high-sensitivity, high-precision sensor needs to be used.
The main method for detecting current in the current circuit system is to use a Hall sensor. The Hall sensor has the advantages of low cost, high precision and the like. But is susceptible to temperature and is subject to significant limitations when applied to outdoor scenes. And based on a tunneling magneto-resistance effect scheme, the detection of bus current is realized by monitoring a magnetic field generated by the current. The scheme is less affected by temperature, and is more suitable for a scene of outdoor weak current detection. Meanwhile, the scheme has the advantages of small volume, high sensitivity, high precision, high integrality, low power consumption, low price, capability of measuring direct current and alternating current signals and the like, and therefore has great application potential.
However, the tunneling magnetoresistance effect scheme has hysteresis effect in mechanism, so that linearity between output voltage and input magnetic field is not high, and therefore, the current sensing scheme based on the tunneling magnetoresistance effect can only be applied to occasions with low requirements on precision, which directly affects application range of the scheme. In order to improve the current detection precision, a closed loop feedback scheme is generally adopted at present, namely an additional magnetic field is generated on the magnetic collecting ring, and the additional magnetic field is equal to the magnetic field generated by the bus current in size and opposite in direction. This solution has the following hidden trouble: (1) the feedback structure leads to more complex circuit structure, improves the system cost and reduces the reliability; (2) the scheme of the feedback magnetic field leads to the limitation of the dynamic range of the system to the output of the feedback magnetic field, and meanwhile, the power consumption of the system is increased along with the increase of bus current; this will further generate more heat, which creates a potential hazard to the reliability of the system; (3) the response rate of the sensing system is limited by the closed loop feedback structure; this greatly limits its application in the power industry.
Therefore, a novel TMR precision compensation method is needed, which is simple and reliable and can be applied to a power system with severe environment.
Disclosure of Invention
Aiming at the defects in the prior art, the application provides the TMR current detection device and the TMR current detection method based on the standard magnetic source, which have strong external interference resistance and high measurement precision.
In order to achieve the above purpose, the present application adopts the following technical scheme:
a TMR current detection device based on a standard magnetic source, comprising: the device comprises a first magnetic induction chip, a second magnetic induction chip, a magnetic ring with two open air gaps, a standard magnetic source, a conductor to be tested, a reference current generation module, a signal processing module and a data processing unit, wherein the first magnetic induction chip and the second magnetic induction chip are respectively arranged at the two open air gaps of the magnetic ring, the output end of the first magnetic induction chip and the output end of the second magnetic induction chip are respectively connected with the input end of the signal processing module, the standard magnetic source is arranged on the magnetic ring, the conductor to be tested is arranged at the center of the magnetic ring, and the reference current generation module generates reference current and outputs the reference current to the standard magnetic source;
the signal processing module comprises a first differential amplifying circuit, a high-pass filter circuit and a second differential circuit, wherein the output end of the first differential amplifying circuit is connected with the input end of the high-pass filter circuit and the positive-phase input end of the second differential circuit, the output end of the high-pass filter circuit is connected with the negative-phase input end of the second differential circuit, the output end of the high-pass filter circuit and the output end of the second differential circuit are respectively connected with the two input ends of the data processing unit, and the data processing unit is used for converting analog electric signals into digital signals and calculating the current flowing on a conductor to be detected through an algorithm.
In order to optimize the technical scheme, the specific measures adopted further comprise:
further, the first magnetic induction chip, the second magnetic induction chip, the conductor to be tested and the magnetic focusing ring form a differential magnetic induction chip assembly; the current in the conductor to be tested passes through to generate a magnetic field, the magnetic field is gathered at the open air gaps through the magnetism gathering ring, and the first magnetic induction cores are respectively arranged at the two open air gapsThe magnetic field to be detected induced by the first magnetic induction chip and the second magnetic induction chip is equal in size and opposite in direction, and the output voltage of the first magnetic induction chip and the second magnetic induction chip is equal to the specific magnetic field B and the sensitivity S c The drift voltage caused by the external stray magnetic field and the reference voltage caused by the reference magnetic field have the following relation:
U 1 ＝U 01 -U G1 -S C B，
U 2 ＝U 02 +U G2 +S C B，
u in 1 、U 2 Output voltages of the first magnetic induction chip and the second magnetic induction chip respectively, U 01 、U 02 The drift voltages of the first magnetic induction chip and the second magnetic induction chip caused by external stray magnetic fields are respectively U G1 、U G2 The output voltage U of the differential magnetic induction chip component is the reference voltage generated by the first magnetic induction chip and the second magnetic induction chip due to the reference magnetic field respectively out The method comprises the following steps:
U out ＝U 2 -U 1 ＝(U 02 -U 01 )+(U G2 +U G1 )+2S C B
the first magnetic induction chip and the second magnetic induction chip are identical in model number such that:
U 01 ＝U 02
U G1 ＝U G2 ＝U G
the expression of the output voltage of the differential magnetic induction chip assembly is as follows:
U out ＝2U G +2S C B
in U G Representing the reference voltage caused by the reference magnetic field.
Further, the reference current generation module comprises a reference waveform generator, a conditioning circuit and a power amplification circuit, wherein the output end of the reference waveform generator is connected with the input end of the conditioning circuit, the output end of the conditioning circuit is connected with the input end of the power amplification circuit, and the output end of the power amplification circuit is connected with the input end of the standard magnetic source.
Further, the first differential amplifying circuit comprises a first operational amplifier A1, a second operational amplifier A2, a third operational amplifier A3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9 and a resistor R10;
one end of the resistor R1 is connected with a first electric signal of the first magnetic induction chip, and the other end of the resistor R1 is connected with a positive input end of the first operational amplifier A1; one end of the resistor R2 is connected with the second electric signal of the first magnetic induction chip, the other end of the resistor R2 is connected with the negative phase input end of the first operational amplifier A1, one end of the resistor R3 is connected with the first electric signal of the second magnetic induction chip, the other end of the resistor R3 is connected with the negative phase input end of the second operational amplifier A2, one end of the resistor R4 is connected with the positive phase input end of the second operational amplifier A2, one end of the resistor R5 is connected with the negative phase input end of the first operational amplifier A1, the other end of the resistor R5 is connected with the output end of the first operational amplifier A1, one end of the resistor R6 is connected with the negative phase input end of the second operational amplifier A2, one end of the resistor R7 is connected with the output end of the first operational amplifier A1, the other end of the resistor R7 is connected with the negative phase input end of the third operational amplifier A3, one end of the resistor R8 is connected with the negative phase input end of the third operational amplifier A3, and the other end of the resistor R9 is connected with the positive phase input end of the third operational amplifier A3.
Further, the high-pass filter circuit includes a capacitor C1 and a resistor R11, wherein one end of the capacitor C1 is used as an input end of the high-pass filter circuit and connected to an output end of the third operational amplifier A3, the other end of the capacitor C1 is used as an output end of the high-pass filter circuit and connected to one end of the resistor R11 and a first input end of the data processing unit, and the other end of the resistor R11 is grounded.
Further, the second differential circuit includes a fourth operational amplifier A4, a resistor R12, a resistor R13, and a resistor R14, where one end of the resistor R12 is connected to the output end of the third operational amplifier A3, the other end of the resistor R12 is connected to the positive phase input end of the fourth operational amplifier A4, one end of the resistor R13 is connected to the negative phase input end of the fourth operational amplifier A4, the other end of the resistor R13 is connected to the output end of the fourth operational amplifier A4, one end of the resistor R14 is connected to the output end of the high-pass filter circuit, the other end of the resistor R14 is connected to the negative phase input end of the fourth operational amplifier A4, and the output end of the fourth operational amplifier A4 is connected to the second input end of the data processing unit.
The application also provides a TMR current detection method based on the standard magnetic source, which comprises the following steps:
the output voltage of the first differential amplifying circuit is subjected to high-pass filtering processing through a high-pass filtering circuit to obtain a reference voltage signal, and then the output voltage of the first differential amplifying circuit and the reference voltage obtained through the high-pass filtering circuit are subjected to differential processing through a second differential circuit to obtain a current I passing through a conductor to be tested P Proportional voltage signal U P The data processing unit is used for processing the voltage signal obtained by the high-pass filter circuit and the current I which is obtained by the second differential circuit and passes through the conductor to be tested P Proportional voltage signal U P And D, performing digital-to-analog conversion, and calculating to obtain the current flowing on the conductor to be measured through an algorithm.
In order to optimize the technical scheme, the specific measures adopted further comprise:
further, the current flowing through the conductor to be measured is calculated by an algorithm specifically:
the current generated by the reference current generating module is I G The current passing through the conductor to be tested is I P The proportionality constant of the output voltage of the current detection device and the current value to be detected is alpha, the hysteresis effect attenuation constant of the magnetic induction chip is beta, and the reference current I of the current detection device G And output voltage U G The following relationship exists:
U G ＝αβI G ，
current I to be measured of current detecting device P And output electricityPressure U P The following relationship exists:
U P ＝αβI P ，
dividing the two to obtain the output voltage U of the current to be detected of the current detection device P Output voltage U of reference current measured by magnetic sensor G Current I generated by reference current generation module G Current I passing through the conductor to be measured P Is the relation of (a):
by a known reference voltage signal U G Current I flowing through standard magnetic source G A voltage signal U obtained by a high-pass filter circuit and a first differential circuit P Calculating the current I flowing through the conductor to be measured P Is of a size of (a) and (b).
The beneficial effects of the application are as follows:
(1) According to the characteristic that the magnetic induction chip is easy to be interfered by an external magnetic field, the two tunneling magnetic resistance magnetic induction chips of the same type are adopted to form a differential structure, so that the common mode signal interference of an external magnetic field on the magnetic induction chip is eliminated, the differential mode signal of the magnetic induction chip is enhanced, the external interference resistance of the current detection device is improved, and the measurement accuracy of a system is improved.
(2) The device adopts an open loop magnetic ring structure, compared with a closed loop feedback structure, the circuit structure of the application is relatively simple, the system cost is reduced, the dynamic range of the system is not limited by the output of a feedback magnetic field any more, the power consumption of the system is reduced, and the stability of the system is improved.
(3) Aiming at the hysteresis effect problem existing in the magnetic induction chip on the mechanism, the application adopts the standard magnetic source to calibrate the error caused by the hysteresis effect of the magnetic induction chip, and carries out analog-digital conversion and real-time algorithm processing on the voltage signal in the data processing unit, thereby compensating the hysteresis effect error and improving the measurement accuracy of the sensor.
The current detection device and the current detection method based on the standard magnetic source have the advantages of low cost, high precision, strong external interference resistance and the like, and are suitable for occasions with complex detection environments of power systems.
Drawings
FIG. 1 is a schematic view of a first construction of a current sensing apparatus according to the present application;
FIG. 2 is a schematic diagram of a second configuration of the current sensing apparatus of the present application;
fig. 3 is a circuit diagram of a differential amplifying circuit in the signal processing module of the present application.
Detailed Description
The application will now be described in further detail with reference to the accompanying drawings.
Referring to fig. 1, a TMR current detection device based on a standard magnetic source of the present application includes: the first magnetic induction chip 1, the second magnetic induction chip 2, the magnetic ring 3 with two open air gaps, the standard magnetic source 4, the conductor to be tested 5, the reference current generating module, the signal processing module and the data processing unit 11, wherein the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively arranged at the two open air gaps of the magnetic ring 3, the output ends of the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively connected with the input end of the signal processing module, the standard magnetic source 4 is arranged on the magnetic ring, the conductor to be tested 5 is arranged at the center of the magnetic ring 3, the first magnetic induction chip 1, the second magnetic induction chip 2, the magnetic ring 3 with two open air gaps and the conductor to be tested 5 form a differential magnetic induction chip assembly, the reference current generating module comprises a reference waveform generator 6, a conditioning circuit 7 and a power amplifying circuit 8, the output end of the reference waveform generator 6 is connected with the input end of the conditioning circuit 7, the output end of the conditioning circuit 7 is connected with the input end of the power amplifying circuit 8, the output end of the power amplifying circuit 8 is connected with the input end of the standard magnetic source 4, the signal processing module comprises a first differential amplifying circuit 9, a high-pass filter circuit 10 and a second differential circuit 12, the output end of the first differential amplifying circuit 9 is connected with the input end of the high-pass filter circuit 10 and the positive phase input end of the second differential circuit 12, the output end of the high-pass filter circuit 10 is connected with the negative phase input end of the second differential circuit 12, the output end of the high-pass filter circuit 10, the output end of the second differential circuit 12 and two input ends of the data processing unit 11 are connected, the data processing unit 11 is configured to convert an analog electrical signal into a digital signal and perform arithmetic processing of the signal.
Referring to fig. 1, the differential magnetic induction chip assembly of the present application is a structure composed of two first magnetic induction chips 1, second magnetic induction chips 2, to-be-measured conductors 5 and magnetic collecting rings 3 of the same type, when current passes through the to-be-measured conductors 5 to generate magnetic fields, the magnetic fields are collected at the open air gaps through the magnetic collecting rings 3, the first magnetic induction chips 1 and the second magnetic induction chips 2 are respectively placed at the two open air gaps, the to-be-measured magnetic fields induced by the two chips are equal in size and opposite in direction, and then the output voltages of the first magnetic induction chips 1 and the second magnetic induction chips 2 are equal to a specific magnetic field B, and the sensitivity S c Drift voltage U caused by external stray magnetic field 0 Reference voltage U caused by reference quasi-magnetic field G The following relationship exists: u (U) 1 ＝U 01 -U G1 -S C B，U 2 ＝U 02 +U G2 +S C B, U in 1 、U 2 Output voltages of the first magnetic induction chip 1 and the second magnetic induction chip 2, U 01 、U 02 Drift voltages caused by external stray magnetic fields of the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively U G1 、U G2 The output voltage U of the differential component is the reference voltage generated by the reference magnetic field of the first magnetic induction chip 1 and the second magnetic induction chip 2 respectively out The method comprises the following steps: u (U) out ＝U 2 -U 1 ＝(U 02 -U 01 )+(U G2 +U G1 )+2S C B, because the magnetic induction chips of the same model have basically the same characteristics, U 01 ＝U 02 ，U G1 ＝U G2 ＝U G The output voltage of the differential magnetic induction chip assembly can then be written as: u (U) out ＝2U G +2S C B。
Referring to fig. 3, the signals generated by the tunneling magneto-resistive magnetic induction module 1 are first and second electrical signals, and the signals generated by the tunneling magneto-resistive magnetic induction chip 2 are third and fourth electrical signals. The signal processing module consists of a differential amplifying circuit, a high-pass filter circuit and a differential circuit. The differential amplifying circuit is composed of a first operational amplifier A1, a second operational amplifier A2, a third operational amplifier A3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10. The positive phase input end of the first operational amplifier A1 is used as a first input end of the differential amplifying circuit, the negative phase input end of the first operational amplifier A1 is used as a second input end of the differential amplifying circuit, the positive phase input end of the second operational amplifier A2 is used as a third input end of the differential amplifying circuit, the negative phase input end of the second operational amplifier A2 is used as a fourth input end of the differential amplifying circuit, and the output end of the third operational amplifier A3 is used as an output end of the differential amplifying circuit. The positive phase input end of the first operational amplifier A1 is connected with one end of a first resistor R1, the negative phase input end of the first operational amplifier A1 is connected with one end of a second resistor R2 and one end of a fifth resistor R5, the positive phase input end of the second operational amplifier A2 is connected with one end of a fourth resistor R4, the negative phase input end of the second operational amplifier A2 is connected with one end of a third resistor R3 and one end of a sixth resistor R6, the output end of the first operational amplifier A1 is connected with the other end of the fifth resistor R5 and one end of a seventh resistor R7, the output end of the second operational amplifier A2 is connected with the other end of the sixth resistor R6 and one end of an eighth resistor R8, the positive phase input end of the third operational amplifier A3 is connected with the other end of the eighth resistor R8 and one end of the tenth resistor R10, the negative phase input end of the third operational amplifier A3 is connected with the other end of the seventh resistor R7 and one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded. The high-pass filter circuit is composed of a first capacitor C1 and an eleventh resistor R11. One end of the first capacitor C1 is used as an input end of the high-pass filter circuit, the other end of the first capacitor C1 and one end of the eleventh resistor R11 are used as output ends of the high-pass filter circuit, and the other end of the eleventh resistor R11 is grounded. The differential circuit is composed of a twelfth resistor R12, a thirteenth resistor R12, a fourteenth resistor R14, and a fourth operational amplifier A4. One end of the twelfth resistor R12 and one end of the resistor R14 are used as input ends of a differential circuit, the output end of the fourth operational amplifier A4 is used as an output end of the differential circuit, the positive input end of the fourth operational amplifier A4 is connected with the other end of the twelfth resistor R12, the negative input end of the fourth operational amplifier A4 is connected with the other end of the fourteenth resistor R14 and one end of the thirteenth resistor R13, and the output end of the fourth operational amplifier A4 is connected with the other end of the thirteenth resistor R13. The output signal of the tunneling magneto-resistance magnetic induction chip 1 is connected with the first input end and the second input end of the differential amplifying circuit, the tunneling magneto-resistance magnetic induction chip 2 is connected with the third input end and the fourth input end of the differential amplifying circuit, the output end of the differential amplifying circuit is connected with the high-pass filter circuit and the input end of the differential circuit, and the output end of the high-pass filter circuit is connected with the input end of the differential circuit and the data processing unit. In the signal processing module, a differential amplifying circuit is formed by adopting a first operational amplifier A1, a second operational amplifier A2 and a third operational amplifier A3, and signals of the tunneling magneto-resistance magnetic induction module 1 and the tunneling magneto-resistance magnetic induction module 2 are subjected to differential and proportional amplification. The first capacitor C1 and the eleventh resistor R11 are adopted to form a high-pass filter circuit, and the output signal of the differential amplifying circuit is subjected to filter processing. And finally, a fourth operational amplifier A4, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14 are adopted to form a differential circuit, and the differential amplifier circuit and the high-pass filter circuit are subjected to difference making to obtain a voltage signal.
In the present application, the current detecting device may have two structures including a magnetism collecting ring and a magnetism collecting ring.
The first structure: as shown in fig. 1, the current detection device comprises a first magnetic induction chip 1, a second magnetic induction chip 2, a magnetic ring 3 with two open air gaps, a standard magnetic source 4, a conductor 5 to be detected, a reference current generation module, a signal processing module and a data processing unit 11, wherein the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively arranged at the two open air gaps of the magnetic ring 3, the output ends of the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively connected with the input end of the signal processing module, the standard magnetic source 4 is arranged on the magnetic ring, the conductor 5 to be detected is arranged at the center of the magnetic ring 3, the reference current generation module comprises a reference waveform generator 6, a conditioning circuit 7 and a power amplification circuit 8, the output end of the reference waveform generator 6 is connected with the input end of the conditioning circuit 7, the output end of the conditioning circuit 7 is connected with the input end of the power amplification circuit 8, the signal processing module comprises a first amplification circuit 9, a high-pass filter circuit 10 and a second differential circuit 12, the output end of the first differential amplification circuit 9 is connected with the output end of the high-pass filter circuit 10 and the output end of the second differential filter circuit 10, and the output end of the second differential filter circuit 12 is connected with the two input ends of the high-pass filter circuit 10 and the second differential filter circuit 12, and the output end of the differential filter circuit is connected with the two input ends of the high-pass filter circuit 12.
As shown in fig. 2, the current detection device comprises a first magnetic induction chip 1, a second magnetic induction chip 2, a first standard magnetic source 3, a second standard magnetic source 4, a conductor 5 to be detected, a reference current generation module, a signal processing module and a data processing unit 11, wherein the first magnetic induction chip 1 and the second magnetic induction chip 2 are arranged on the same side of the conductor 5 to be detected, the output ends of the first magnetic induction chip 1 and the second magnetic induction chip 2 are respectively connected with the input end of the signal processing module, the first standard magnetic source 3 is arranged above the first magnetic induction chip 1, the second standard magnetic source 4 is arranged below the first magnetic induction chip 2, the reference current generation module comprises a reference waveform generator 6, a conditioning circuit 7 and a power amplification circuit 8, the output end of the reference waveform generator 6 is connected with the input end of the conditioning circuit 7, the output end of the conditioning circuit 7 is connected with the input end of the power amplification circuit 8, and the output end of the power amplification circuit 8 is respectively connected with the input ends of the first standard magnetic source 3 and the second standard magnetic source 4.
The current detection method of the current detection device comprises the following steps: first, the output voltage U of the first differential amplifying circuit 9 is outputted by the high-pass filter circuit 10 out The high-pass filtering process is performed to obtain a reference voltage signal, and then the output voltage U obtained by the first differential amplifying circuit 9 is outputted by the second differential circuit 12 out And the reference voltage obtained by the high-pass filter circuit 10 to obtain a current I passing through the conductor 5 to be tested P Proportional voltage signalU P Then the voltage signal obtained by the high-pass filter circuit 10 and the current I which is obtained by the second differential circuit 12 and passes through the conductor 5 to be tested are processed by the data processing unit 11 P Proportional voltage signal U P Digital-to-analog conversion and algorithm processing are performed.
In the above current detection method, the algorithm processing procedure is as follows: current I generated by reference current generation module G Current I passing through conductor 5 to be measured P The proportional constant of the output voltage of the magnetic sensor and the current value to be measured is alpha, the hysteresis effect attenuation constant of the magnetic sensor is beta, and the reference current output voltage U of the magnetic sensor G The following relationship exists: u (U) G ＝αβI G Measuring current output voltage U of magnetic sensor P The following relationship exists: u (U) P ＝αβI P The output voltage U of the current measured by the magnetic sensor can be obtained after the two are divided and arranged P Output voltage U of reference current measured by magnetic sensor G Current I generated by reference current generation module G Current I passing through the conductor to be measured P The following relationship exists:by a known reference voltage signal U G Current I flowing in standard G Voltage signal U obtained by high-pass filter circuit and differential circuit P Can calculate the I of the current flowing on the conductor to be measured P Size of the product.
It should be noted that the terms like "upper", "lower", "left", "right", "front", "rear", and the like are also used for descriptive purposes only and are not intended to limit the scope of the application in which the application may be practiced, but rather the relative relationship of the terms may be altered or modified without materially altering the teachings of the application.
The above is only a preferred embodiment of the present application, and the protection scope of the present application is not limited to the above examples, and all technical solutions belonging to the concept of the present application belong to the protection scope of the present application. It should be noted that modifications and adaptations to the application without departing from the principles thereof are intended to be within the scope of the application as set forth in the following claims.
Claims (8)
1. A TMR current detection device based on a standard magnetic source, comprising: the device comprises a first magnetic induction chip (1), a second magnetic induction chip (2), a magnetic ring (3) with two open air gaps, a standard magnetic source (4), a conductor to be detected (5), a reference current generation module, a signal processing module and a data processing unit (11), wherein the first magnetic induction chip (1) and the second magnetic induction chip (2) are respectively arranged at the two open air gaps of the magnetic ring (3), the output end of the first magnetic induction chip (1) and the output end of the second magnetic induction chip (2) are respectively connected with the input end of the signal processing module, the standard magnetic source (4) is arranged on the magnetic ring (3), the conductor to be detected (5) is arranged at the center of the magnetic ring, and the reference current generation module generates a reference current and outputs the reference current to the standard magnetic source (4);
the signal processing module comprises a first differential amplifying circuit (9), a high-pass filter circuit (10) and a second differential circuit (12), wherein the output end of the first differential amplifying circuit (9) is connected with the input end of the high-pass filter circuit (10) and the positive-phase input end of the second differential circuit (12), the output end of the high-pass filter circuit (10) is connected with the negative-phase input end of the second differential circuit (12), the output end of the high-pass filter circuit (10) and the output end of the second differential circuit (12) are respectively connected with two input ends of a data processing unit (11), and the data processing unit (11) is used for converting analog electric signals into digital signals and calculating the current flowing on a conductor (5) to be detected through an algorithm.
2. The TMR current detection device based on standard magnetic source according to claim 1, wherein the first magnetic induction chip (1), the second magnetic induction chip (2), the conductor to be detected (5) and the magnetic focusing ring (3) form a differential magnetic induction chip assembly; the conductor (5) to be tested generates a magnetic field after current passes through, the magnetic field is concentrated at the open air gaps through the magnetic concentrating ring (3), a first magnetic induction chip (1) and a second magnetic induction chip (2) are respectively placed at the two open air gaps, and the first magnetic induction coreThe magnetic fields to be detected induced by the sheet (1) and the second magnetic induction chip (2) are equal in size and opposite in direction, and the output voltage of the first magnetic induction chip (1) and the second magnetic induction chip (2) is equal to a specific magnetic field B and sensitivity S c The drift voltage caused by the external stray magnetic field and the reference voltage caused by the reference magnetic field have the following relation:
U 1 ＝U 01 -U G1 -S C B，
U 2 ＝U 02 +U G2 +S C B，
u in 1 、U 2 Output voltages of the first magnetic induction chip (1) and the second magnetic induction chip (2), U 01 、U 02 The drift voltages of the first magnetic induction chip (1) and the second magnetic induction chip (2) caused by external stray magnetic fields are respectively U G1 、U G2 The output voltage U of the differential magnetic induction chip component is the reference voltage generated by the first magnetic induction chip (1) and the second magnetic induction chip (2) due to the reference magnetic field respectively out The method comprises the following steps:
U out ＝U 2 -U 1 ＝(U 02 -U 01 )+(U G2 +U G1 )+2S C B
the first magnetic induction chip (1) and the second magnetic induction chip (2) are the same in model number, so that:
U 01 ＝U 02
U G1 ＝U G2 ＝U G
the expression of the output voltage of the differential magnetic induction chip assembly is as follows:
U out ＝2U G +2S C B
in U G Representing the reference voltage caused by the reference magnetic field.
3. The TMR current detection device based on a standard magnetic source according to claim 1, wherein the reference current generation module comprises a reference waveform generator (6), a conditioning circuit (7) and a power amplification circuit (8), an output end of the reference waveform generator (6) is connected with an input end of the conditioning circuit (7), an output end of the conditioning circuit (7) is connected with an input end of the power amplification circuit (8), and an output end of the power amplification circuit (8) is connected with an input end of the standard magnetic source (4).
4. The TMR current detection device based on a standard magnetic source according to claim 1, wherein the first differential amplification circuit (9) includes a first operational amplifier A1, a second operational amplifier A2, a third operational amplifier A3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a resistor R10;
one end of the resistor R1 is connected with a first electric signal of the first magnetic induction chip (1), and the other end of the resistor R1 is connected with a positive input end of the first operational amplifier A1; one end of the resistor R2 is connected with a second electric signal of the first magnetic induction chip (1), the other end of the resistor R2 is connected with the negative phase input end of the first operational amplifier A1, one end of the resistor R3 is connected with the first electric signal of the second magnetic induction chip (2), the other end of the resistor R3 is connected with the negative phase input end of the second operational amplifier A2, one end of the resistor R4 is connected with the positive phase input end of the second operational amplifier A2, one end of the resistor R5 is connected with the negative phase input end of the first operational amplifier A1, one end of the resistor R5 is connected with the negative phase input end of the second operational amplifier A2, the other end of the resistor R6 is connected with the output end of the second operational amplifier A2, one end of the resistor R7 is connected with the output end of the first operational amplifier A1, the other end of the resistor R7 is connected with the negative phase input end of the third operational amplifier A3, one end of the resistor R8 is connected with the negative phase input end of the third operational amplifier A3, and the other end of the resistor R8 is connected with the positive end of the third operational amplifier A9 of the third operational amplifier A2, and the other end of the resistor R9 is connected with the positive end of the third operational amplifier A3.
5. The TMR current detection device based on a standard magnetic source according to claim 4, wherein the high-pass filter circuit (10) includes a capacitor C1 and a resistor R11, one end of the capacitor C1 is connected to the output end of the third operational amplifier A3 as the input end of the high-pass filter circuit (10), the other end of the capacitor C1 is connected to one end of the resistor R11 and the first input end of the data processing unit (11) as the output end of the high-pass filter circuit (10), and the other end of the resistor R11 is grounded.
6. The TMR current detection device based on a standard magnetic source according to claim 5, wherein the second differential circuit (12) includes a fourth operational amplifier A4, a resistor R12, a resistor R13, and a resistor R14, one end of the resistor R12 is connected to the output terminal of the third operational amplifier A3, the other end of the resistor R12 is connected to the positive phase input terminal of the fourth operational amplifier A4, one end of the resistor R13 is connected to the negative phase input terminal of the fourth operational amplifier A4, the other end of the resistor R13 is connected to the output terminal of the fourth operational amplifier A4, one end of the resistor R14 is connected to the output terminal of the high-pass filter circuit (10), the other end of the resistor R14 is connected to the negative phase input terminal of the fourth operational amplifier A4, and the output terminal of the fourth operational amplifier A4 is connected to the second input terminal of the data processing unit (11).
7. A TMR current detection method based on a standard magnetic source, comprising:
the output voltage of the first differential amplifying circuit (9) is subjected to high-pass filtering processing through a high-pass filter circuit (10) to obtain a reference voltage signal, and then the output voltage of the first differential amplifying circuit (9) and the reference voltage obtained through the high-pass filter circuit (10) are subjected to differential processing through a second differential circuit (12) to obtain a current I passing through a conductor (5) to be tested P Proportional voltage signal U P The voltage signal obtained by the high-pass filter circuit (10) and the current I which is obtained by the second differential circuit (12) and passes through the conductor (5) to be tested are processed by the data processing unit (11) P Proportional voltage signal U P Performing digital-to-analog conversion, and calculating to obtain the current flowing through the conductor (5) to be measured through an algorithm.
8. The TMR current detection method based on a standard magnetic source according to claim 7, wherein the magnitude of the current flowing through the conductor (5) to be detected obtained by calculation through an algorithm is specifically:
the current generated by the reference current generating module is I G The current passing through the conductor (5) to be measured is I P The proportionality constant of the output voltage of the current detection device and the current value to be detected is alpha, the hysteresis effect attenuation constant of the magnetic induction chip is beta, and the reference current I of the current detection device G And output voltage U G The following relationship exists:
U G ＝αβI G ，
current I to be measured of current detecting device P And output voltage U P The following relationship exists:
U P ＝αβI P ，
dividing the two to obtain the output voltage U of the current to be detected of the current detection device P Output voltage U of reference current measured by magnetic sensor G Current I generated by reference current generation module G And the current I passing through the conductor (5) to be measured P Is the relation of (a):
by a known reference voltage signal U G Current I flowing through standard magnetic source G A voltage signal U obtained by a high-pass filter circuit (10) and a first differential circuit (9) P Calculating the current I flowing through the conductor to be measured P Is of a size of (a) and (b).
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