CN106950516B - A weak eddy current magnetic field measurement device and method - Google Patents
A weak eddy current magnetic field measurement device and method Download PDFInfo
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Abstract
The present invention provides a kind of weak swirl magnetic field measuring device and method, for measuring the eddy current magnetism of measurand, wherein, the device includes a screened room, a Helmholtz coil, a measurand saddle and a Magnetic Sensor are equipped in the screened room, the screened room is externally provided with a data synchronisation source, a signal source, a power amplifier and a data acquisition components；Wherein, the measurand saddle is located at the field homogeneity area of the Helmholtz coil, and the signal source and the power amplifier are sequentially connected in series between the data synchronisation source and the Helmholtz coil；The data acquisition components are connected between the data synchronisation source and the Magnetic Sensor.The present invention not only improves the measurement accuracy of eddy current magnetism, simplifies the measuring process of eddy current magnetism, but also integrally can carry out precise measurement by the eddy current magnetism to large scale system.
Description
Technical field
The present invention relates to magnetic-field measurement field more particularly to a kind of weak swirl magnetic field measuring device and methods.
Background technique
The full tensor magnetic gradient measurements system of aviation superconduction is by carrying magnetic survey equipment on airborne platform, using flying
The magnetic anomaly information as caused by magnetic mineral resources obtained in journey, to realize magnetic ore body high efficiency, high-precision over the ground
The three-dimensional localization of degree, and obtain their space distribution information., with detection efficient height, unit area operating cost is low to wait spies for it
Point is to carry out one of the important means of resource investigation and screening target prospecting area.
Because of the factor of radio shielding, electromagnetic compatibility and mechanical machinability etc., the aviation superconduction developed is opened entirely
More or less can all there be metal parts in amount magnetic gradient measurements system, and when system carries out aviation flight magnetic measurement, these
Metal parts can generate vortex because cutting earth magnetic field in flight course, survey to influence the full tensor magnetic gradient of aviation superconduction
The measurement accuracy of amount system.Because the full tensor magnetic gradient measurements system of aviation superconduction need to have very high magnetic survey accuracy of measurement (0.05nT/
M), so the vortex for needing to cut system metal parts in flight course earth magnetic field generation carries out quantitative evaluation, and
Sometimes the whirlpool cutting earth magnetic field in flight course and generating whole to the full tensor magnetic gradient measurements system of aviation superconduction is also needed
Stream carries out quantitative evaluation.
" eddy current magnetism method of measuring " in " electromechanical equipment " Chinese periodical 2011 volume 28 discloses a kind of whirlpool
Flow Measurement Method for Magnetic Field.A kind of measurement side that eddy current magnetism is generated using simulation warship swing cutting magnetic line is proposed in this article
Method, and use circle copper sheet for simple model, it proves in terms of theoretical research and test result two, is produced using coil electrifying method
Life, measurement eddy current magnetism are feasible.Although eddy current magnetism measurement may be implemented in the method that this article is announced, but disadvantage is also apparent from: its
One, measurement accuracy is influenced vulnerable to external magnetic field, is difficult to realize the measurement of weak swirl (such as < 5nT) indoors；Second, vortex
The alternating magnetic field and non-uniform magnetic-field that coil generates, to be that uniform reality is not inconsistent with the earth magnetic field actually cut, in turn
Influence the Evaluated effect of its excitation vortex；Third, the eddy current magnetism obtained only has amplitude information, but there is no phase information；Fourth,
It is both needed to adjust the parameter of its feedback system when magnetic probe changes position or replacement magnetic probe, measuring process is cumbersome；Fifth,
Measurand can not effectively measure eddy current magnetism there are when induced magnetic field.In addition, eddy current sensor currently on the market is most only
It is capable of measuring the relative quantity of eddy current magnetism, cannot achieve the precise quantification of eddy current magnetism absolute value, and can not be to large scale system
The eddy current magnetism of system carries out precise measurement.
In conclusion existing eddy current magnetism measurement method not only has that measurement accuracy is not high and measuring process is cumbersome etc. and asks
Topic, there is also can not eddy current magnetism effectively to large scale system carry out precise measurement the problems such as, and the survey in weak swirl magnetic field
Amount is most important to the aviation superconducting magnetic measuring system with strategic importance, to be guided out the design of the application.
Summary of the invention
In order to solve the limitation of existing eddy current magnetism measurement method, the present invention provide it is a kind of based on synchronous data collection and
The weak swirl magnetic field measuring device and method of Helmholtz coil not only improve the measurement accuracy of eddy current magnetism, simplify vortex
The measuring process in magnetic field, and integrally can carry out precise measurement by the eddy current magnetism to large scale system.
In order to solve the above-mentioned technical problem, one aspect of the present invention provides a kind of weak swirl magnetic field measuring device, for surveying
The eddy current magnetism of measurand is measured, which includes a screened room, is tested in the screened room equipped with a Helmholtz coil, one
Object saddle and a Magnetic Sensor, the screened room are externally provided with a data synchronisation source, a signal source, a power amplifier and a number
According to acquisition component；
Wherein, the measurand saddle is located at the field homogeneity area of the Helmholtz coil, the signal source and institute
Power amplifier is stated to be sequentially connected in series between the data synchronisation source and the Helmholtz coil；The data acquisition components connect
It connects between the data synchronisation source and the Magnetic Sensor.
Preferably, the outer wall of the screened room side is equipped with a magnetic screen pipeline for passing through outer wall setting, the function
Connection cables and the data acquisition components between rate amplifier and the Helmholtz coil and the Magnetic Sensor it
Between connection cables pass through the shielded conduit.
Preferably, the Magnetic Sensor is fluxgate or superconductive magnetometer.
Preferably, the data synchronisation source is function generator or GPS receiver.
Preferably, the signal source is function generator or digital analog converter.
Another aspect of the present invention provides a kind of weak swirl Measurement Method for Magnetic Field, and this method uses aforementioned weak swirl magnetic field
Measuring device measures the eddy current magnetism of measurand.
Further, when the induced magnetic field of the measurand is negligible, method includes the following steps:
The measurand is fixedly mounted on the measurand saddle by measurement direction, closes the magnetic cup by S11
It covers room, and the data acquisition components is controlled described in the signal source and power amplifier driving by the data synchronisation source
When Helmholtz coil, the magnetic field value of the measurement of Magnetic Sensor described in synchronous acquisition；
The measurand is removed from the screened room, closes the magnetic shield room, and pass through the data by S12
Synchronisation source controls the data acquisition components when the signal source and power amplifier drive the Helmholtz coil, synchronous
Acquire the magnetic field value of Magnetic Sensor measurement, wherein the vortex excitation that the Helmholtz coil generates in this step with
The vortex excitation generated in the step S11 is identical；
Collected magnetic field value in the step S11 is subtracted collected magnetic field value in the step S12, obtained by S13
Difference be the measurand eddy current magnetism.
Further, when the induced magnetic field of the measurand be can not ignore, method includes the following steps:
The measurand is fixedly mounted on the measurand saddle by measurement direction, closes the magnetic cup by S21
Room is covered, the measurand is sought in the Helmholtz coil and generates the induced magnetic field under very low frequencies vortex incentive environment；
S22 controls the data acquisition components by the data synchronisation source and drives in the signal source and power amplifier
When moving the Helmholtz coil, the magnetic field value of the measurement of Magnetic Sensor described in synchronous acquisition；
The measurand is removed from the screened room, closes the magnetic shield room, and pass through the data by S23
Synchronisation source controls the data acquisition components when the signal source and power amplifier drive the Helmholtz coil, synchronous
Acquire the magnetic field value of Magnetic Sensor measurement, wherein the vortex excitation that the Helmholtz coil generates in this step with
The vortex excitation generated in the step S22 is identical；
The magnetic field value collected in the step S22 is subtracted the collected magnetic in the step S23 by S24
Field value, obtained difference is the sum of eddy current magnetism and induced magnetic field of the measurand；
S25, by being adopted to the induced magnetic field obtained in the step S21 according to the frequency ratio of vortex excitation again
After sample, the eddy current magnetism is solved by algebraic operation.
Further induced magnetic field described in the step S21 is sought being achieved by the steps of:
S211 seeks the permanent magnetic field of the measurand；
S212, in the signal source output stage low frequency signal to drive the Helmholtz coil to generate ultra low yield point steel
When, pass through the magnetic field value of the measurement of Magnetic Sensor described in the data acquisition components synchronous acquisition；
Collected magnetic field value in the step S212 is subtracted permanent magnetic field obtained in the step S211, obtained by S213
To difference be the measurand induced magnetic field.
Further, permanent magnetic field described in the step S211 is sought being achieved by the steps of:
S2111 leads to when the signal source exports direct current signal to drive the Helmholtz coil to generate stationary magnetic field
Cross the magnetic field value of the measurement of Magnetic Sensor described in the data acquisition components synchronous acquisition；
S2112, makes that the direct current signal amplitude of signal source output is constant, polarity is on the contrary, by the data acquisition group
The magnetic field value of the measurement of Magnetic Sensor described in part synchronous acquisition；
S2113 is obtained again divided by 2 after being added the step S211 with collected magnetic field value in the step S212
To the permanent magnetic field of the measurand.
The invention has the advantages that can be while realizing eddy current magnetism measurement, easily by changing vortex
Driving frequency and signal processing solve the problems, such as that there are the measurements of eddy current magnetism when induced magnetic field, and synchronous data collection easy to use
Improve the precision of eddy current magnetism measurement.In addition, the data acquisition device realization by this method building is simple, easy to operate, reliably
Property it is high, be very suitable to the test in weak swirl magnetic field and large scale system entirety eddy current magnetism.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples.
Fig. 1 is the hardware structural diagram of this bright invention weak swirl magnetic field measuring device；
Fig. 2 is the measurement flow chart of weak swirl magnetic field measuring device when placing measurand；
Fig. 3 is the measurement flow chart of weak swirl magnetic field measuring device when not placing measurand；
Fig. 4 is the measurement flow chart of the permanent magnetic field of measurand；
Fig. 5 is the measurement flow chart of the induced magnetic field of measurand；
In figure: 1. magnetic shield rooms, 2. Helmholtz coils, 3. measurands, 4. measurand saddles, 5. Magnetic Sensor supports
Platform, 6. Magnetic Sensors, 7. magnetic screen pipelines, 8. data acquisition components, 9. signal sources, 10. power amplifiers, 11. data are synchronous
Source.
Specific embodiment
To be more clear the purpose of the present invention, concrete scheme and advantage, below in conjunction with specific embodiment, and referring to attached
Figure, the present invention is described in more detail.
Weak swirl magnetic field measuring device of the invention is as shown in Figure 1, include magnetic shield room 1, Helmholtz coil 2, quilt
Survey object 3, measurand saddle 4, Magnetic Sensor saddle 5, Magnetic Sensor 6, magnetic screen pipeline 7, data acquisition components 8, signal
Source 9, power amplifier 10 and data synchronisation source 11.Wherein: the outer wall of 1 side of magnetic shield room is equipped with the magnetic cup across the outer wall
Pipeline 7 is covered, Helmholtz coil 2 is placed in the central area of magnetic shield room 1, and the central area of Helmholtz coil 2 is placed
Measurand saddle 4, for the measurand saddle 4 for fixing measurand 3, the magnetic field for being at Helmholtz coil 2 is equal
Even area.Magnetic Sensor 6 is fixedly mounted on Magnetic Sensor saddle 5, and is similarly positioned in magnetic shield room 1, but its specific location can
According to the tested point of the size of measurand 3 and eddy current magnetism be selectively mounted to Helmholtz coil 2 inside or
It is external.Because of EMC Design, to prevent from interfering with each other between associated component in weak swirl magnetic field measuring device, therefore by data
Acquisition component 8, signal source 9, power amplifier 10 and data synchronisation source 11 are both placed in the outside of magnetic shield room 1, wherein counting
Magnetic Sensor 6 is connected by the coaxial cable once magnetic screen pipeline 7 according to acquisition component 8, and power amplifier 10 is by another
Coaxial cable through magnetic screen pipeline 7 connects Helmholtz coil 2.Data synchronisation source 11 is used for 8 He of synchronous data collection component
Signal source 9 is respectively connected to the sync cap of data acquisition components 8 and the external trigger of signal source 9 so that its output is divided into two
Interface.Signal source 9 is usually limited because of driving capability, can not be directly driven Helmholtz coil 2 and be generated and swash needed for Eddy current test
It encourages (such as ± 45 μ T), therefore in its output end connection power amplifier 10 to promote current driving ability.
The working principle of weak swirl magnetic field measuring device of the present invention is: generating identical vortex in Helmholtz coil 2 and swashs
In the environment of encouraging, measured in same position whether there is or not Magnetic Field when two kinds of measurand using data are synchronous, they
Algebraic step is required eddy current magnetism, and wherein premise is that the induced magnetic field of measurand should can be ignored.Concrete methods of realizing is such as
Under: Helmholtz coil 2, measurand saddle 4 and Magnetic Sensor 6 are placed first in magnetic shield room 1, wherein Helmholtz
Coil 2 can be it is three-dimensional, it with outside magnetic shield room 1 power amplifier 10 and signal source 9 be sequentially connected, and provide whirlpool together
Excitation needed for flow measurement, and Magnetic Sensor 6 often selects fluxgate or superconductive magnetometer, for obtaining the magnetic field of designated position
Information；Then outside magnetic shield room 1, the sync cap of the external trigger interface of signal source 9 and data acquisition components 8 is connected to
Data synchronisation source 11, wherein data synchronisation source 11, which can be, can provide the function generator of square wave, be also possible to that PPS letter can be provided
Number GPS receiver；Secondly, being synchronized using data synchronisation source 11 to data acquisition components 8 and signal source 9, and closing
Magnetic shield room 1 and in the case where not placing measurand, gets background magnetic field by Magnetic Sensor 6；Finally closing magnetic cup
In the case where covering room 1 and placing measurand, equally under the premise of data acquisition components 8 are synchronous with signal source 9, passed by magnetic
Sensor 6 gets the magnetic field comprising vortex, so that this magnetic field for including vortex, which is subtracted background magnetic field exactly, needs whirlpool to be requested
Flow magnetic field.
For generating the component of vortex excitation, the function with external trigger function common in the market is usually may be selected in signal source 9
Generator, such as the 33522B function generator of Keysight company, but if the background signal and eddy current magnetism signal of measurement
Ratio is excessive, the dynamic range (usually 80dB) of excessive function generator, then to guarantee to measure faint eddy current magnetism, believes
The 24 digit mode converters based on PXI bus, such as the NI4461 of NI company can be used in number source；Power amplifier 10 mainly for
9 output power of signal source is insufficient, amplifies its output signal, to drive Helmholtz coil 2 to provide and generate vortex excitation institute
The electric current needed；Helmholtz coil 2 then mainly for generation of uniform exchange variation magnetic field, wherein measurand should be placed on by
It surveys on object saddle 3, and is located in the field homogeneity area for generating the Helmholtz coil 2 of vortex excitation, so as to without distortions
The earth magnetic field that system is actually cut during simulated flight.In addition, Helmholtz coil 2 can be according to the size of measurand
It is customized, and three-dimensional Helmholtz coil can be used, so that analog practical flight attitude data, meets large scale system
Whole Eddy current test demand.
For the associated component of synchronous data collection, data synchronisation source 11, which generally selects, can provide the function generation of square wave
Device, also can choose can provide the GPS receiver of PPS signal, they make the signal for generating vortex excitation in a manner of external trigger
Source 9 is synchronous with data acquisition components 8, i.e., while making the output vortex excitation of signal source 9 by rising edge or failing edge, data
Acquisition component 8 is synchronous to start to work；Data acquisition components 8 are mainly used for being connected with Magnetic Sensor 6, acquire its output signal, with
Eddy current magnetism is calculated, it is usually customizable, 24 high-accuracy data acquisitions of the NI company based on CompactRIO platform also can be selected
System；Magnetic Sensor 6 is mainly used for obtaining the Magnetic Field of designated position, can be placed on the last of the twelve Earthly Branches according to space and the selection of magnetic field size
Mu Huozi coil 2 either internally or externally, generally selects fluxgate or superconductive magnetometer, wherein superconductive magnetometer can measure
Fainter eddy current magnetism.It is using the benefit of synchronous data collection: because the front and back of eddy current magnetism measures twice, entire measurement dress
Set only that this factor changes whether there is or not measurand, thus measurement result also only with whether there is or not this factor of measurand is related
Connection, thus the influence of the factors such as response magnetic field that negligible signal delay, surrounding objects are generated by vortex excitation.
When the induced magnetic field of measurand 3 be can not ignore, because induced magnetic field can also change with vortex pumping signal, thus
Remnant field after carrying out algebraic step with background magnetic field includes not only eddy current magnetism, but also including induced magnetic field, therefore aforementioned
Measurement method needs are modified, but measuring device need not change.For there are the measurand of induced magnetic field, modified whirlpools
Flow measuring method is: the permanent magnetic field of measurand is solved first with stationary magnetic field；Then it is motivated using the vortex of very low frequencies
Solve corresponding induced magnetic field；The induced magnetic field and vortex magnetic of measurand are finally measured according to aforementioned eddy current measuring method
The sum of, because induced magnetic field in the case where no hysteresis not with the frequency shift of driving source, therefore by the induction magnetic solved
After field carries out resampling according to the frequency ratio of vortex excitation, eddy current magnetism to be solved can be solved by algebraic operation.It has
Body implementation method is as follows: placing measurand, and the both direction phase successively generated using it in Helmholtz coil 2 first
Instead, but the same stationary magnetic field of amplitude, the algebra of two groups of measurand permanent magnetic fields and induced magnetic field is got by aforementioned device
Combination, i.e., permanent magnetic field adds induced magnetic field and permanent magnetic field to subtract induced magnetic field, so as to solve measurand by mathematical computations
Permanent magnetic field；Then the environment of very low frequencies vortex excitation (amplitude and vortex excitation to be solved are consistent) is generated in Helmholtz coil 2
Under, using data synchro measure Magnetic Sensor same measurement position output, wherein very low frequencies (such as 0.01Hz) measure
When, it should be ensured that its eddy current magnetism vortex relatively to be measured is negligible at this time, so that measurement result be made only to include induced magnetic field and permanent magnetism
, and then using the permanent magnetic field solved, the induced magnetic field of measurand is solved by algebraic manipulation；Finally in Hai Muhuo
In the environment of hereby coil 2 generates vortex excitation to be solved, according to the eddy current measuring method in aforementioned non-inductive magnetic field, magnetic sensing is recorded
Device 6 same measurement position output, because measurement result include induced magnetic field and eddy current magnetism, by the induction magnetic solved
The frequency ratio (frequency ratio that the i.e. aforementioned vortex generated twice by 2 front and back of Helmholtz coil motivates) that field is motivated according to vortex
Resampling is carried out to obtain after the induced magnetic field under vortex excitation to be solved, whirlpool to be solved can be solved by algebraic operation
Magnetic field is flowed, solution procedure is as follows: the aforementioned measurement result comprising induced magnetic field and eddy current magnetism being subtracted into resampling and is obtained only
Measurement result comprising induced magnetic field obtains eddy current magnetism.
The method that measures measurand eddy current magnetism is discussed in detail using the measuring device in Fig. 1 step by step below:
When the induced magnetic field of measurand is negligible, needs to measure whether there is or not magnetic field when measurand, there is measurand
When measurement procedure it is as shown in Figure 2, comprising: step 1 starts, i.e. the relevant preparation of development Eddy current test；Step 2, test
Device is built, i.e., builds weak swirl magnetic field measuring device according to Fig. 1, and is sequentially connected relevant cable；Step 3 places quilt
Object is surveyed, i.e., is fixedly mounted on measurand 3 on measurand saddle 4 by measurement direction；Step 4, system electrification are being closed
After closing magnetic shield room 1, synchronous data collection component 8, signal source 9, power amplifier 10 and data synchronisation source 11 are successively opened
Power supply；Step 5, running parameter setting, i.e., by eddy current magnetism testing requirement setting synchronous data collection component 8, signal source 9,
The running parameter of power amplifier 10 and data synchronisation source 11, such as sample rate, the signal source 9 of synchronous data collection component 8
The gain of the frequency and amplitude, power amplifier 10 of output signal；Step 6, simulation generate synchronous vortex excitation, that is, pass through number
According to synchronisation source 11 in a manner of external trigger, make the rising edge or failing edge and signal source 9 of 11 output signal of data synchronisation source
Output signal is synchronous, and wherein signal source 9 should work under burst mode, to generate rising edge every time in data synchronisation source 11
Or when failing edge, the magnetic field for driving Helmholtz coil 2 to generate through power amplifier 10 is also consistent, simultaneously because magnetic shield room
1 reason, the vortex excitation for acting on measurand 3 are also approximately constant；Step 7, synchronous data collection utilize Hai Muhuo
The magnetic field that hereby coil 2 the generates feature synchronous with data synchronisation source 11, the equally rising based on 11 output signal of data synchronisation source
Produce data acquisition components 8 and Helmholtz coil 2 along perhaps failing edge with the operating mode of external trigger or GPS resampling
Raw field synchronous carries out data acquisition, and wherein data acquisition components 8 select 24 based on CompactRIO platform of NI company
High Precise Data Acquisition System；Step 8 obtains magnetic measurement data, i.e., completes the measurement of Magnetic Sensor 6 in data acquisition components 8
Afterwards, the data that data acquisition components 8 measure are read.
Measurement procedure when without measurand is as shown in Figure 3, comprising: step 1 starts, i.e. development background magnetic field tests phase
The preparation of pass；Step 2 opens magnetic shield room 1, i.e., after completing measurement by Fig. 2, open the gate of magnetic shield room 1；3rd
Step removes measurand 3, i.e., measurand 3 is put into 1 outside of magnetic shield room from the shifting of measurand saddle 4；Step 4 closes screen
Room 1 is covered, that is, closes the gate of magnetic shield room 1；Step 5, running parameter setting 23, i.e., by eddy current magnetism test same in Fig. 2
Demand keeps the running parameter of synchronous data collection component 8, signal source 9, power amplifier 10 and data synchronisation source 11 not
Become；Step 6, simulation generate synchronous vortex excitation, the operating procedure vortex incentive step synchronous with the simulation generation in Fig. 2
Equally, i.e., data synchronisation source 11 in a manner of external trigger, make rising edge or the decline of 11 output signal of data synchronisation source
Edge is synchronous with the output signal of signal source 9, and wherein signal source 9 should work under burst mode, thus every in data synchronisation source 11
When secondary generation rising edge or failing edge, the magnetic field for driving Helmholtz coil 2 to generate through power amplifier 10 is also consistent, simultaneously
Due to the reason of magnetic shield room, the vortex excitation for acting on measurand 3 is also approximately constant；Step 7, synchronous data collection,
For its operating procedure as the synchronous data collection 18 in Fig. 2, i.e., the magnetic field generated using Helmholtz coil 2 is synchronous with data
The synchronous feature in source 11, equally rising edge or failing edge based on 11 output signal of data synchronisation source, with the work of external trigger
Mode or GPS resampling make the field synchronous of data acquisition components 8 and the generation of Helmholtz coil 2, wherein data acquisition group
Part 8 selects 24 High Precise Data Acquisition Systems of the NI company based on CompactRIO platform；Step 8 obtains background magnetic field, i.e.,
After the measurement that data acquisition components 8 complete Magnetic Sensor 6, the data that data acquisition components 8 measure are read, because of measurement process
In there is no measurand 3, and other test conditions are the same, therefore the data read are exactly background magnetic needed for seeking eddy current magnetism
?.
After successively completing test according to Fig. 2 and testing process shown in Fig. 3, it can be neglected in the induced magnetic field of measurand 3
In the case where slightly, the difference of the test result of the two is eddy current magnetism of the measurand 3 in 4 present position of measurand saddle.
In the case where the induced magnetic field of measurand 3 be can not ignore, the difference of the test result of above-mentioned Fig. 2 and Fig. 3, not only
Comprising eddy current magnetism, but also including induced magnetic field, therefore eddy current magnetism is sought out, induced magnetic field must be removed.In view of
Under the premise of there is no magnetic hysteresis, quilt when induced magnetic field is not actuated to very low frequencies signal with the characteristic and vortex of driving source frequency shift
The insignificant characteristic of vortex of object 3 is surveyed, therefore after solving induced magnetic field by very low frequencies driving source, according to the frequency of vortex excitation
Rate can solve eddy current magnetism to be solved than carrying out resampling by algebraic operation.
Induced magnetic field to be solved need to first obtain permanent magnetic field, and the test device for solving permanent magnetic field is also shown in FIG. 1.Quilt
The measurement procedure for surveying object permanent magnetic field is as shown in Figure 4, comprising: step 1 starts, i.e. development 3 permanent magnetic field of measurand test is related
Preparation；Step 2 places measurand, i.e., measurand 3 is fixedly mounted on measurand saddle 4 by measurement direction
On, and the gate of magnetic shield room 1 is closed, keep the stable magnetic field inside magnetic shield room；Step 3 loads stationary magnetic field, i.e., will letter
Work is arranged under DC mode in number source 9, and after its running parameter is arranged according to testing requirement, makes its output through power amplification
Device 10 drives Helmholtz coil 2 to generate constant test magnetic field；Step 4 records magnetic measurement data, i.e., in data acquisition components
After 8 complete the measurement of Magnetic Sensor 6, the data in 8 memory of data acquisition components are read, this data includes measurand induction
Magnetic field and permanent magnetic field algebraical sum；Step 5, running parameter modification, that is, modify the running parameter of signal source 9, it is made to export direct current letter
Number amplitude it is constant, but the pole reversal；Step 6, the opposite stationary magnetic field of loading direction, i.e., by the output of signal source 9 through power
Amplifier 10 drives Helmholtz coil 2 to generate constant test magnetic field, the reverse magnetic field that direction and step 3 generate；7th
Step records magnetic measurement data, i.e., after the measurement that data acquisition components 8 complete Magnetic Sensor 6, reads data acquisition components 8 and deposit
Data in reservoir, this data equally include the algebraical sum of measurand induced magnetic field and permanent magnetic field, but it includes induction magnetic
Field is contrary with step 4 measurement；Step 8 calculates permanent magnetic field, i.e., is added step 4 with the data that step 7 measures, then remove
The permanent magnetic field that can be obtained measurand 3 with 2.
Because induced magnetic field be change with external magnetic field, therefore obtain measurand 3 permanent magnetic field after, be from Fig. 2 and Fig. 3
Measurement result in remove induced magnetic field, need to obtain the induced magnetic field under corresponding excitation.The survey of measurand induced magnetic field
It is as shown in Figure 5 to measure process, comprising: step 1 starts, i.e. development 3 induced magnetic field of measurand tests relevant preparation；2nd
Step keeps measurand position constant, i.e., keeps the position in Fig. 4 measurement process constant measurand 3；Step 3 is more converted to
Number running parameter, i.e., reset signal source 9 under work burst mode, and reset relevant work by the step 5 of Fig. 2
Make parameter, but the working frequency of signal source 9 needs to be adjusted to very low frequencies, such as 0.01Hz, to eliminate eddy current magnetism in measurement process
Influence；Step 4 loads the vortex excitation of very low frequencies, i.e., the output of signal source 9 is driven Helmholtz through power amplifier 10
The test magnetic field of the generation very low frequencies of coil 2；Step 5 records magnetic measurement data, i.e., completes Magnetic Sensor 6 in data acquisition components 8
Measurement after, read 8 memory of data acquisition components in data, this data includes the very low frequencies induced magnetic field of measurand 3
With the algebraical sum of constant permanent magnetic field；Step 6 solves induced magnetic field, i.e., subtracts the test data of step 5 by Fig. 4 testing process
The permanent magnetic field of acquisition, so that it may obtain the very low frequencies induced magnetic field under the excitation of 3 step 4 of measurand；Step 7, repeatedly measurement is asked
Induced magnetic field average value, i.e., repeatedly step 4 is to step 6, and the 3 very low frequencies induced magnetic field of measurand that will acquire is averaging, to mention
High measurement accuracy.
Based on the running parameter in Fig. 2 and Fig. 3 testing process, measurand 3 is obtained according to the testing process of Fig. 4 and Fig. 5
After the induced magnetic field under corresponding excitation, include induced magnetic field and vortex magnetic in view of the measurement result by Fig. 2 and Fig. 3 testing process
, to can be transported by algebra after by carrying out resampling according to the frequency ratio of vortex excitation to the induced magnetic field solved
Calculation solves eddy current magnetism to be solved.
Particular embodiments described above has carried out further in detail the purpose of the present invention, technical scheme and beneficial effects
It describes in detail bright, it should be understood that the above is only a specific embodiment of the present invention, is not intended to restrict the invention, it is all
Within the spirit and principles in the present invention, any modification, equivalent substitution, improvement and etc. done should be included in guarantor of the invention
Within the scope of shield.
Claims (12)
1. a kind of weak swirl Measurement Method for Magnetic Field, which is characterized in that this method using a weak swirl magnetic field measuring device come
The eddy current magnetism of measurand is measured, the weak swirl magnetic field measuring device includes a screened room, is equipped in the screened room
One Helmholtz coil, a measurand saddle and a Magnetic Sensor, the screened room are externally provided with a data synchronisation source, a signal
Source, a power amplifier and a data acquisition components；Wherein, the measurand saddle is located at the magnetic of the Helmholtz coil
Field homogeneity range, the signal source and the power amplifier are sequentially connected in series in the data synchronisation source and the Helmholtz coil
Between；The data acquisition components are connected between the data synchronisation source and the Magnetic Sensor,
When the induced magnetic field of the measurand is negligible, method includes the following steps:
The measurand is fixedly mounted on the measurand saddle by measurement direction, closes the magnetic screen by S11
Room, and the data acquisition components are controlled by the data synchronisation source and drive the last of the twelve Earthly Branches in the signal source and power amplifier
When Mu Huozi coil, the magnetic field value of the measurement of Magnetic Sensor described in synchronous acquisition；
S12 removes the measurand from the screened room, closes the magnetic shield room, and synchronous by the data
Source controls the data acquisition components when the signal source and power amplifier drive the Helmholtz coil, synchronous acquisition
The magnetic field value of the Magnetic Sensor measurement, wherein the vortex that the Helmholtz coil generates in this step motivates and in institute
It is identical to state the vortex excitation generated in step S11；
Collected magnetic field value in the step S11 is subtracted collected magnetic field value in the step S12, obtained difference by S13
Value is the eddy current magnetism of the measurand.
2. weak swirl Measurement Method for Magnetic Field according to claim 1, which is characterized in that the outer wall of the screened room side
It is equipped with a magnetic screen pipeline for passing through outer wall setting, the connection between the power amplifier and the Helmholtz coil
Connection cables between cable and the data acquisition components and the Magnetic Sensor pass through the shielded conduit.
3. weak swirl Measurement Method for Magnetic Field according to claim 1, which is characterized in that the Magnetic Sensor is fluxgate
Or superconductive magnetometer.
4. weak swirl Measurement Method for Magnetic Field according to claim 1, which is characterized in that the data synchronisation source is function
Generator or GPS receiver.
5. weak swirl Measurement Method for Magnetic Field according to claim 1, which is characterized in that the signal source is function
Device or digital analog converter.
6. a kind of weak swirl Measurement Method for Magnetic Field, which is characterized in that this method using a weak swirl magnetic field measuring device come
The eddy current magnetism of measurand is measured, the weak swirl magnetic field measuring device includes a screened room, is equipped in the screened room
One Helmholtz coil, a measurand saddle and a Magnetic Sensor, the screened room are externally provided with a data synchronisation source, a signal
Source, a power amplifier and a data acquisition components；Wherein, the measurand saddle is located at the magnetic of the Helmholtz coil
Field homogeneity range, the signal source and the power amplifier are sequentially connected in series in the data synchronisation source and the Helmholtz coil
Between；The data acquisition components are connected between the data synchronisation source and the Magnetic Sensor,
When the induced magnetic field of the measurand be can not ignore, method includes the following steps:
The measurand is fixedly mounted on the measurand saddle by measurement direction, closes the magnetic screen by S21
Room seeks the measurand in the Helmholtz coil and generates the induced magnetic field under very low frequencies vortex incentive environment；
S22 controls the data acquisition components by the data synchronisation source and drives institute in the signal source and power amplifier
When stating Helmholtz coil, the magnetic field value of the measurement of Magnetic Sensor described in synchronous acquisition；
S23 removes the measurand from the screened room, closes the magnetic shield room, and synchronous by the data
Source controls the data acquisition components when the signal source and power amplifier drive the Helmholtz coil, synchronous acquisition
The magnetic field value of the Magnetic Sensor measurement, wherein the vortex that the Helmholtz coil generates in this step motivates and in institute
It is identical to state the vortex excitation generated in step S22；
The magnetic field value collected in the step S22 is subtracted the collected magnetic field value in the step S23 by S24,
Obtained difference is the sum of eddy current magnetism and induced magnetic field of the measurand；
S25, by carrying out resampling according to the frequency ratio of vortex excitation to the induced magnetic field obtained in the step S21
Afterwards, by the way that the sum of the eddy current magnetism and induced magnetic field obtained in the step S24 are subtracted the induction magnetic that resampling obtains
Field solves the eddy current magnetism.
7. weak swirl Measurement Method for Magnetic Field according to claim 6, which is characterized in that feel described in the step S21
Magnetic field is answered to seek being achieved by the steps of:
S211 seeks the permanent magnetic field of the measurand；
S212 leads to when the signal source output stage low frequency signal is to drive the Helmholtz coil to generate ultra low yield point steel
Cross the magnetic field value of the measurement of Magnetic Sensor described in the data acquisition components synchronous acquisition；
Collected magnetic field value in the step S212 is subtracted permanent magnetic field obtained in the step S211, obtained by S213
Difference is the induced magnetic field of the measurand.
8. weak swirl Measurement Method for Magnetic Field according to claim 7, which is characterized in that described in the step S211 forever
It seeks being achieved by the steps of in magnetic field:
S2111 passes through institute when the signal source exports direct current signal to drive the Helmholtz coil to generate stationary magnetic field
State the magnetic field value of the measurement of Magnetic Sensor described in data acquisition components synchronous acquisition；
S2112, makes that the direct current signal amplitude of signal source output is constant, polarity is on the contrary, same by the data acquisition components
Step acquires the magnetic field value of the Magnetic Sensor measurement；
S2113 obtains institute again divided by 2 after being added the step S211 with collected magnetic field value in the step S212
State the permanent magnetic field of measurand.
9. weak swirl Measurement Method for Magnetic Field according to claim 6, which is characterized in that the outer wall of the screened room side
It is equipped with a magnetic screen pipeline for passing through outer wall setting, the connection between the power amplifier and the Helmholtz coil
Connection cables between cable and the data acquisition components and the Magnetic Sensor pass through the shielded conduit.
10. weak swirl Measurement Method for Magnetic Field according to claim 6, which is characterized in that the Magnetic Sensor is magnetic flux
Door or superconductive magnetometer.
11. weak swirl Measurement Method for Magnetic Field according to claim 6, which is characterized in that the data synchronisation source is letter
Number generator or GPS receiver.
12. weak swirl Measurement Method for Magnetic Field according to claim 6, which is characterized in that the signal source is function hair
Raw device or digital analog converter.
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| CN111458572A (en) * | 2020-05-07 | 2020-07-28 | 中汽研汽车检验中心（天津）有限公司 | Vehicle electromagnetic field human body protection test metering system and method |
| CN111596107B (en) * | 2020-07-06 | 2022-03-08 | 扬州大学 | Electromagnetic eddy current simulation and test platform |
| CN112130217B (en) * | 2020-08-21 | 2021-08-06 | 中国地质大学（武汉） | Electrical detection system and method for angle between geometric axis and magnetic axis of coil vector magnetometer |
| CN114397615A (en) * | 2021-12-09 | 2022-04-26 | 贵州电网有限责任公司 | Magnetic field sensor calibration system |
| CN117347929A (en) * | 2023-09-26 | 2024-01-05 | 中国科学院国家空间科学中心 | A magnetic testing device and measurement method with controllable magnetic field angle |
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