CN107121489A - A kind of alternating current field measurement instrument - Google Patents
A kind of alternating current field measurement instrument Download PDFInfo
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- CN107121489A CN107121489A CN201710235160.8A CN201710235160A CN107121489A CN 107121489 A CN107121489 A CN 107121489A CN 201710235160 A CN201710235160 A CN 201710235160A CN 107121489 A CN107121489 A CN 107121489A
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- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/83—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields
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Abstract
A kind of ac magnetic field crackle detecting instrument based on FPGA includes FPGA digital circuits, DDS driving sources, power amplification circuit, excitation coil, detection sensor, preamplifier, signal regulating panel, A/D converter circuit, key circuit and telecommunication circuit.Using control chips of the FPGA as alternating current field measurement system, the excitation source module of design frequency and phase-adjustable, design communication electromagnetic field detection sensor, signal conditioning circuit, A/D converter circuit and telecommunication circuit.The solution have the advantages that:Design the alternating current field measurement digital circuitry controlled based on fpga chip, realize alternating current field measurement instrument to the control of peripheral hardware circuit module, overcome current detection apparatus measures narrow range, measurement accuracy difference and the single shortcoming of measurement, improve the flexibility of detection and intelligent, can be applied to work high above the ground and complicated measured workpiece.
Description
Technical field
The present invention relates to a kind of detector, more particularly to a kind of alternating current field measurement instrument.
Background technology
Alternating current field measurement technology（Alternating Current Field Measurement）It is to be based on faraday
The active scanning detection technology of electromagnetic induction principle, the technology is applied to submerged structure and the sea of oil and natural gas earliest
In the Non-Destructive Testing of platform device, under water occur missing inspection in order to solve conventional lossless detection method in detection platform and fail to judge
Problem.The technology utilizes electromagnetic induction principle in workpiece for measurement surface induction alternating current, by measuring workpiece surface or near surface
Defect judges induced field formed by the disturbance of alternating current the size of defect, and then evaluates the state and property of workpiece for measurement
Energy.
Alternating current field measurement technology is the NDE centers base by department of mechanical engineering of London University in the 1980s
In AC voltage drop（ACPD）The new method of proposition.Lewis have studied the coupling of outer workpiece magnetic field and Surface field within 1988,
It is uniformly distributed based on drive surface current field and establishes ACFM（Alternating Current Field Measurement, letter
Claim ACFM）General theoretical model.External alternating current field measurement technology initial design source is the detection for welding line structure, with
The development for the technology has been widely applied to be used for the inspection of petroleum industry first at the end of other industry, the 1980s
Survey.
In actual life surface and near surface crackle for workpiece harm clearly, easily cause potential safety hazard.Gold
Category material is generally used as stressed member in real life, long-term in-service in use, in fatigue load, stress corrosion and interior
Under the influence of external environment condition, it is very easy to produce surface in stress concentration, loose, weld seam and weld heat-affected zone or near surface is split
Line.The information such as length, width, the depth of crackle can quickly, be easily and accurately detected, and then evaluate surface and near surface
Crackle, has huge practical value for the use of in-service equipment, for preventing the generation of peril significant.
The detection of face crack generally has the detection methods such as magnetic, infiltration and ultrasonic wave, is examined for the crackle containing buried depth
Survey usual effect poor, and it requires metal surface higher, it is necessary to carry out paint removal to metal surface, go clad etc. to clear up
Work, it is coarse more difficult with deep water detection in surface of test piece, considerably increase detection time and difficulty.Ray detection can be answered
For the detection of surface and near surface crackle, but so that its security is low, instrument is heavy and is very limited.Ac magnetic field
Detection is with noncontact, detection speed be fast, lift-off factor influences that small, detection sensitivity is high, the features such as can be achieved quantitatively to detect, can
It is widely used in the industries such as Aero-Space, petroleum pipeline, railway traffic and pressure vessel, has broad application prospects.
Although thering is R＆D institution to develop alternating current field measurement pertinent instruments at present in China, its application still phase
When narrow and small, measurement sensitivity and the degree of accuracy have much room for improvement.Bigger effort is still needed in terms of engineer applied, alternating-current field detection is improved
Intellectuality and detection efficiency, can be by fractional hardware circuitry software using slave computers of the FPGA as alternating current field measurement
Change design, so as to improve the flexibility of the detecting system and intelligent, and reduce design cost, the country is had applied to actual inspection
The product of survey.
The content of the invention
It is an object of the invention to provide a kind of special digital circuit based on FPGA alternating current field measurement instrument and accordingly
Hardware module, the actually detected parameter of ac magnetic field can be adjusted by key circuit, the intellectuality of detection is improved, can
Detection applied to different materials measured workpiece.
The technical solution adopted by the present invention is as follows：A kind of alternating current field measurement instrument, mainly include FPGA digital circuits,
DDS excitations source module, power amplification circuit, excitation coil, detection sensor, preamplifier, signal regulating panel, AD conversion electricity
Road, key circuit and telecommunication circuit；It is characterized in that：Instrument overall circuit design block diagram is as shown in Figure 1：FPGA control DDS excitations
The sinusoidal signal that source module is produced inputs to excitation coil after power amplification circuit, and excitation coil and detection sensor connect
Connect, excitation coil and detection sensor constitute detection probe, and detection sensor is connected with preamplifier, preamplifier and letter
Number conditioning plate is connected, and signal regulating panel is connected with A/D converter circuit, and A/D converter circuit is connected with FPGA digital circuits, key circuit
It is connected with FPGA digital circuits, FPGA digital circuits are connected with telecommunication circuit.
Further, the present invention is used as the control chip of alternating current field measurement system, design communication electromagnetism using FPGA
Field detection digital circuit, realizes control of the slave computer to hardware module.
Further, detection sensor of the invention is made up of TMR magnetoresistance effect sensors, can measure two directions
Magnetic field, produce differential signal.
Further, the input clock frequency of FPGA control signal conditioning plates of the invention, it is adaptable to which different materials are treated
Survey workpiece.
Further, FPGA of the invention controls the AD conversion of alternating current field measurement, and realizes the communication with host computer.
Further, the present invention can adjust the frequency and phase of excitation source module composite signal by key circuit.
The excitation source module that domestic most of alternating current field measurement instrument are used at present is all the signal using in the market
Generation circuit module, its control mode is relatively complicated.The DDS excitation source modules synthesized using slave computer not only reduce peripheral electricity
The space of road module, and integrated detecting system is easy to control, improves the flexibility of detecting system.Passed using TMR magnetic resistance
Sensor improves detection sensitivity as magnetic field probe, and it detects that stability is higher, without the need for reset is put, detects
Scope is wide.
The present invention can produce frequency and the sinusoidal signal of phase-adjustable using fpga chip control DDS excitation source modules, right
It can improve driving frequency to detect in the measured workpiece of nonmetallic materials；Detection sensor is reduced using magnetic resistance sensor
The area of probe, the detection range of sensor is wider, at the same it is higher than the stability of coil type detection sensor, can directly it survey
Measure the magnetic field in Bx, Bz direction；Signal conditioning circuit is by FPGA controls, it is possible to achieve the filtering of signal is detected to different frequency.
FPGA digital circuits determine actually detected mode and efficiency as the master control layer of alternating current field measurement.By changing the number
Word circuit can carry out the maintenance and upgrading of system, while by part peripheral hardware modulas, reducing ac magnetic field
The cost of detection, further improves the integration degree of instrument.
The present invention is achieved in that FPGA control high speed D/A change-over circuit synthesis sinusoidal signals, by power amplifier
Exchange electric excitation is provided to excitation coil, alternating current is induced in metal surface to be checked, alternating current runs into workpiece for measurement surface
Or the defect rear of near surface senses magnetic to deflecting in the disturbance horizontally and vertically produced of surface of test piece
, the changes of magnetic field of both direction is converted into differential signal by detection sensor, and signal tune is delivered to after amplifying through preamplifier
Manage plate processing, after signal regulating panel is filtered, deliver to high-speed AD acquisition chip collection, two paths of signals gathered through AD after with SPI
The mode of bus is transmitted to FPGA and processing in real time is transmitted to host computer processing.Verilog HDL Hardware description languages are used herein
The application specific integrated circuit of design communication electromagnetic field detection system is sayed, system includes master control layer and bottom module, and bottom module is friendship
The real-time control digital circuit of electromagnetic field detection hardware module is flowed, master control layer is system control module, including bottom module and inspection
The control of examining system.
The solution have the advantages that：Overcome current alternating current field measurement instrument and use the scarce of periphery excitation source module
Point；Overcome the cumbersome shortcoming of current alternating electromagnetic field control driving frequency；Overcome current ac magnetic field system upgrade
Difficulty, devises the alternating current field measurement digital circuit based on FPGA, by fractional hardware software implementation；Improve ac magnetic field
The flexibility of detection.Overcome the current shortcoming that alternating current field measurement instrument detection range is small, detection sensitivity is low.
Brief description of the drawings
Alternating current field measurement instrument theory diagrams of the Fig. 1 based on FPGA.
In figure, 1, DDS driving sources, 2, power amplification circuit 3, excitation coil 4, detection sensor 5, preamplifier 6,
Signal regulating panel 7, A/D converter circuit 8, FPGA digital circuits 9, telecommunication circuit 10, key circuit.
Embodiment
Below in conjunction with the accompanying drawings 1 and instantiation the present invention is described in detail.
A kind of alternating current field measurement instrument, circuit connection diagram is as shown in Figure 1：DDS driving sources 1, power amplification circuit 2, swash
Encourage coil 3, detection sensor 4, preamplifier 5, signal regulating panel 6, A/D converter circuit 7, FPGA digital circuits 8, communication electricity
Road 9 and key circuit 10.It is characterized in that：The connection DDS of FPGA digital circuits 8 driving sources 1, the same power amplification circuit of DDS driving sources 1
2 are connected, and power amplification circuit 2 is connected with excitation coil 3, and excitation coil 3 and detection sensor 4 are connected, and detection sensor 4 is the same
Put amplifier 5 to be connected, the signal regulating panel 6 of preamplifier 5 is connected, signal regulating panel 6 is connected with A/D converter circuit 7, AD conversion
Circuit 7 is connected with FPGA controls 8, and FPGA digital circuits 8 are connected with telecommunication circuit 9, and key circuit 10 is with the phase of FPGA control systems 8
Even.
Whole detecting instrument includes detection probe, preamplifier, signal regulating panel, DDS excitations source module, AD conversion electricity
Road, key circuit, FPGA digital circuits and telecommunication circuit.Wherein detection probe is made up of excitation coil and detection sensor, is used
Signal is detected in extracting；Preamplifier and signal regulating panel are handled detection signal, and preamplifier includes RC low passes
Filter circuit and magnifier, signal conditioning circuit include bandpass filtering, voltage follower, true effective value converting circuit；
DDS excitation source modules include high speed D/A change-over circuit, I/V change-over circuits and power amplification circuit, for producing ac magnetic field
The excitation of detection；A/D converter circuit carries out analog-to-digital conversion to detection signal, is digitized processing；FPGA digital circuits are used to control
Peripheral module processed, realizes the control to testing process；Key circuit can realize the control to peripheral hardware module function；Communication
Circuit completes the transmission with host computer.
The hardware circuit module of alternating current field measurement instrument is controlled by FPGA, and it is public that fpga chip employs Altera
The family chips of Cyclone IV of department, chip model is EP4CE6E22C8N.In the design process of the instrument, mainly give
The connected mode of the function that each module is realized between module.
The principle that source module is encouraged based on FPGA design is DDS (Direct Digital Frequency Systhesis)
Direct digital synthesis technique, the scope of composite signal frequency can be improved by improving DA chips digit, can also pass through design
DA digital circuits are improved.FPGA control high speed D/A change-over circuit synthesis sinusoidal signals, high speed D/A conversion chip uses DAC900,
Excitation coil is supplied to after amplifying by power amplification circuit, by key circuit can adjust synthesis sinusoidal signal frequency and
Phase, it is adaptable to the tested material of difference.
Detection sensor 4 is made up of TMR2301 magnetic resistance sensors, is placed in below excitation coil, and be disposed vertically and treat
Survey workpiece surface.The voltage signal that detection sensor is extracted is differential signal, and can be by Hz noise, nothing in detection environment
Line radio station and the influence of electrostatic interference.The preamplifier of Differential Input is designed to carry out primary suppression noise, preamplifier
Using AD8226, suppress Radio frequency interference in detection signal input port design RC low-pass filter circuits herein, while can be every
From input circuit and signal source, the detection signal after amplification is suitable for subsequent conditioning circuit processing.
Signal regulating panel designs bandwidth-limited circuit using LTC1068 chips, and its clock frequency is provided by FPGA, clock
Frequency has a fpga chip offer.Pass through the digital circuit of clock frequency needed for fpga chip control signal conditioning plate, inspection
Survey personnel only need to regulation FPGA and export and can change center frequency filtering to the clock frequency of signal regulating panel, so as to realize pair
The detection of different materials defect, it is adaptable to the detection signal of different frequency input.
A/D converter circuit is using TLC1549 chips as AD conversion chip, and TLC1549 is 10 successive approximations of single channel
Modulus conversion chip, when the operating voltage using 3.3V, its resolution ratio is 3.2mV, and the resolution ratio can meet detecting system
Demand.FPGA digital circuitries determine the process of detection, can be to alternating current field measurement by changing FPGA digital circuits
It is controlled, controls the peripheral module of alternating current field measurement, is conducive to the maintenance and upgrading of ac magnetic field.
The technological thought of embodiment of above only to illustrate the invention, every technological thought according to the present invention, in technology
Any change done on the basis of scheme, each falls within protection scope of the present invention.
Claims (6)
1. a kind of alternating current field measurement instrument, mainly includes FPGA digital circuits, DDS and encourages source module, power amplification circuit, swashs
Encourage coil, detection sensor, preamplifier, signal regulating panel, A/D converter circuit, key circuit and telecommunication circuit；Its feature
It is：The sinusoidal signal that FPGA control DDS excitation source modules are produced inputs to excitation coil, excitation line after power amplification circuit
Circle and detection sensor connection, detection sensor are connected with preamplifier, and preamplifier is connected with signal regulating panel, signal
Conditioning plate is connected with A/D converter circuit, and A/D converter circuit is connected with FPGA digital circuits, and key circuit is with FPGA digital circuit phases
Even, FPGA digital circuits are connected with telecommunication circuit.
2. alternating current field measurement instrument according to claim 1, it is characterized in that：Alternating current field measurement is used as using FPGA
The control chip of system, design communication electromagnetic field detection digital circuit realizes control of the slave computer to hardware module.
3. alternating current field measurement instrument according to claim 1, it is characterized in that：Detection sensor is by TMR magneto-resistance effects
Sensor is constituted, and can measure the magnetic field in two directions, produces differential signal.
4. alternating current field measurement instrument according to claim 1, it is characterized in that：During the input of FPGA control signal conditioning plates
Clock frequency, it is adaptable to the workpiece for measurement of different materials.
5. alternating current field measurement instrument according to claim 1, it is characterized in that：FPGA controls the AD of alternating current field measurement
Conversion, and realize the communication with host computer.
6. alternating current field measurement instrument according to claim 1, it is characterized in that：Driving source can be adjusted by key circuit
The frequency and phase of module composite signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710235160.8A CN107121489A (en) | 2017-04-12 | 2017-04-12 | A kind of alternating current field measurement instrument |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710235160.8A CN107121489A (en) | 2017-04-12 | 2017-04-12 | A kind of alternating current field measurement instrument |
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| CN107121489A true CN107121489A (en) | 2017-09-01 |
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| CN201710235160.8A Pending CN107121489A (en) | 2017-04-12 | 2017-04-12 | A kind of alternating current field measurement instrument |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107956468A (en) * | 2017-12-06 | 2018-04-24 | 中石化石油工程技术服务有限公司 | Oil-base mud electric imaging logging instrument frequency Adaptable System |
| CN108254627A (en) * | 2018-01-31 | 2018-07-06 | 杭州圣远医疗科技有限公司 | Electromagnetic field waveform signal acquires control methods and device |
| CN108458932A (en) * | 2018-04-20 | 2018-08-28 | 大连理工大学 | A method of measuring sandy gravel three axis sample local deformations of dynamic using electromagnetic induction technology |
| CN111307930A (en) * | 2020-03-31 | 2020-06-19 | 广东省特种设备检测研究院顺德检测院 | Alternating-current electromagnetic field detection probe for detecting defects of still kettle and detection system thereof |
| CN113390475A (en) * | 2021-01-29 | 2021-09-14 | 张军虎 | Multifunctional metering module and rotary metering device |
| WO2022166002A1 (en) * | 2021-02-05 | 2022-08-11 | 杭州为峰智能科技有限公司 | Anti-radio frequency interference metering module and rotation counting device |
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| US6400146B1 (en) * | 2000-09-12 | 2002-06-04 | Her Majesty The Queen In Right Of Canada As Represented By The Ministry Of Natural Resources | Sensor head for ACFM based crack detection |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107956468A (en) * | 2017-12-06 | 2018-04-24 | 中石化石油工程技术服务有限公司 | Oil-base mud electric imaging logging instrument frequency Adaptable System |
| CN108254627A (en) * | 2018-01-31 | 2018-07-06 | 杭州圣远医疗科技有限公司 | Electromagnetic field waveform signal acquires control methods and device |
| CN108458932A (en) * | 2018-04-20 | 2018-08-28 | 大连理工大学 | A method of measuring sandy gravel three axis sample local deformations of dynamic using electromagnetic induction technology |
| CN108458932B (en) * | 2018-04-20 | 2019-11-19 | 大连理工大学 | A method of utilizing electromagnetic induction technology measurement sandy gravel three axis sample local deformations of dynamic |
| CN111307930A (en) * | 2020-03-31 | 2020-06-19 | 广东省特种设备检测研究院顺德检测院 | Alternating-current electromagnetic field detection probe for detecting defects of still kettle and detection system thereof |
| CN113390475A (en) * | 2021-01-29 | 2021-09-14 | 张军虎 | Multifunctional metering module and rotary metering device |
| WO2022166002A1 (en) * | 2021-02-05 | 2022-08-11 | 杭州为峰智能科技有限公司 | Anti-radio frequency interference metering module and rotation counting device |
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Application publication date: 20170901 |