CN205482768U - Detection circuit for displacement sensor - Google Patents
Detection circuit for displacement sensor Download PDFInfo
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- CN205482768U CN205482768U CN201521002203.0U CN201521002203U CN205482768U CN 205482768 U CN205482768 U CN 205482768U CN 201521002203 U CN201521002203 U CN 201521002203U CN 205482768 U CN205482768 U CN 205482768U
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Abstract
The utility model provides a pair of detection circuit for displacement sensor, the built -in coil equivalence of sensor is internal resistance RL and the series connection of inductance L, other end ground connection was connected to one end after current -limiting resistor R, internal resistance RL, inductance L and sampling resistor RS established ties with pulse generation modules, detecting element detects the voltage at sampling resistor RS both ends or flows through sampling resistor RS's electric current. The utility model discloses an establish displacement sensor physical model, build the internal resistance RL of the built -in coil of the direct real -time calculation sensor of detection circuitry, and according to coil internal resistance real -time calculation sensor inductance L, the internal resistance RL who isolates through the judgement, judge the operating condition of sensor, because testing process inductance L calculates with internal resistance RL's separation to go on in real time, do not need the outer resource of increase just can provide in the real -time supervision of system function (BIT), very big degree has reduced complexity, improve the reliability and reduced the consumption.
Description
Technical field
This utility model relates to sensor detecting field, is specifically related to the testing circuit of a kind of displacement transducer.
Background technology
Tradition displacement detecting mechanism is that mechanically-based formula microswitch realizes, scaling loss easy to wear by mechanical contact；Yi Yin
Liquid and dust pollution and lost efficacy；Position-limit mechanism need to be equipped with；The defect factors restrictions such as press device fatiguability inefficacy, based on fine motion
Traditional displacement detecting mechanism of switch is gradually substituted by detection technique based on inductive displacement transducer, to obtain key displacements
The high reliability of testing agency and high precision test.Such technology is widely used in industrial circle, and is gradually expanded to the army and the people
With key position detections such as the landing-gear system of aviation aircraft, wing-folding system, brake system, hatch door, radomes
Mechanism and warship oceangoing ship equipment field.
Displacement detecting technology based on inductive proximity sensor is at industrial circle, all with the form of inductance approach switch
Application, and essentially active electrical eddy current type.Operationally, operating frequency is high, to external radiation high frequency magnetic field also for such proximity switch
Producing the electric field that energy is higher so that the Electro Magnetic Compatibility of such proximity switch is poor, simultaneously because of its operation principle, sensor is built-in
All there is temperature sensitive factor in coil and circuit structure, causes such proximity switch ambient temperature to adapt to ability, it is impossible to meet
Use requirement under rugged surrounding temperature and complex electromagnetic fields environment so that such technology in aviation and weaponry field
Application is restricted.
In order to meet the use requirement under adverse circumstances, France's Crouzet and Ke Rui company of the U.S. release non-current vortex successively
Inductance approach switch, because of its low operating frequency, low-power consumption, the feature product of all-metal sealing has good Electro Magnetic Compatibility
And contamination resistance.The product that two companies release all at the probe internally provided coil of product, tested metal target close to and
During popping one's head in away from proximity switch, the inductance value of proximity switch internal coil changes, by building analog or digital
Coil inductance variable quantity is processed as measurable signal of telecommunication by circuit, and according to change correspondence output close to and away from switch letter
Number.Detection method selected by two companies is all by probe coil is applied pumping signal, feeds back according to the excitation of coil
Signal extraction inductance coil variable quantity, including coil discharge and recharge time constant and phase contrast.But in proximity switch probe coil
Capacitance-resistance easily changes, in analog detecting method can not be rejected while extracting coil discharge and recharge time constant because of temperature impact
The impact of resistance.Digital Detecting Method extracts voltage by algorithm and current and phase difference calculates and reject Coil resistance, thus reaches
The purpose of suppression temperature drift, but algorithm structure causes, and such technology poor real, structure are complicated, reliability is low.
Because traditional method can not respectively obtain cell winding inductance value and internal resistance value accurately, cause the prior art cannot
Realizing at system real time monitoring function (BIT), inductance detection precision low causing can only identify that connecing of tested metal target is proximal and distal
From state, it is impossible to the displacement information that accurate output is quantitative.
Utility model content
For solving above-mentioned technical problem, this utility model provides the testing circuit of a kind of displacement transducer, and this displacement passes
The testing circuit of sensor, by simple circuit structure, signal extraction and filtering policy, uses simple calculating to efficiently solve
Current art resistance to ambient temperature capability difference and the problem that the accurate inductance value of cell winding cannot be obtained.
This utility model is achieved by the following technical programs.
The testing circuit of a kind of displacement transducer that this utility model provides, including impulse generating unit, detector unit, limit
Leakage resistance R, sensor internal coil and sample resistance RS, described sensor internal coil is equivalent to internal resistance RLConnect with inductance L,
Described current-limiting resistance R, internal resistance RL, inductance L and sample resistance RSAfter series connection, one end is connected with impulse generating unit, other end ground connection；
Described detector unit detection sample resistance RSThe voltage at two ends or flow through sample resistance RSElectric current.
Described detector unit is that analog-digital converter, current sense amplifier, current sensor etc. can will flow through sampling electricity
The electric current of resistance RS or its both end voltage are converted into the circuit of digital quantity.
Described impulse generating unit is digital signal processor DSP, single-chip microprocessor MCU, single-chip digital frequency synthesis chip
DDS, programmable logic device (CPLD)/FPGA, risc microcontroller ARM etc. can produce the circuit of pulse signal.
The detection method of the testing circuit of a kind of displacement transducer, comprises the following steps:
(1) use impulse generating unit output drive pulse to testing circuit；
(2) detector unit measures sample resistance RSThe voltage at two ends also converses and flows through sample resistance RSElectric current, or directly
Measurement flows through sample resistance RSElectric current；
(3) sample resistance R is flowed through by detectSElectric current can draw the electric current of flows through sensor coil, set up electricity
The single order zero state response function of sense coil, and according to flowing through the change of coil current under unit interval variable quantity, solve respectively
Go out Coil resistance RLAnd coil inductance L；
(4) internal resistance R is setLSpan and the excursion of inductance L；
(5) metal target range sensor sensitive surface change in displacement situation is judged according to the change of the inductance L detected.
Also include step (6): according to the internal resistance R detectedLValue judge the duty of sensor.
By zero moment i in described step (3)(0+)=i(0-)=0, the response of circuit is zero state response；Flow through coil and take
Sample resistance RSElectric current be:
Wherein, imFor loop maximum current, τ is time constant；
T, detector unit detection flows through sample resistance RSElectric current itOr detect its both end voltage U1, can be flow through
The electric current of sample resistance is:
Individual through (3～5)τAfter time, exciter response convergence terminates；The electric current flowing through coil reaches maximum im, detection is single
Unit detects and flows through sample resistance RSElectric current imOr detect its both end voltage U2, can obtain flowing through the maximum current of sample resistance
For:
Formula (2), formula (3) and formula (4) are substituted into formula (1), and arrangement obtains
In equation (5), Um、RS, R, t be known quantity, U1、U2Obtained, by solving equation by detector unit sampling
Obtain cell winding inductance L and internal resistance RL。
In described step (5) when inductance L is more than threshold value Ga set, it is believed that measured target is close；When inductance L is less than
Set threshold value Gd time, it is believed that measured target away from.
Internal resistance R in described step (6)LValue more than the higher limit of its span time, then judge that cell winding is disconnected
Line state；Internal resistance RLValue less than the lower limit of its span time, then judge that cell winding is short-circuit condition.
The beneficial effects of the utility model are: by setting up displacement transducer physical model, build testing circuit direct
Calculate the internal resistance R of sensor internal coil in real timeL, and sensors inductance L is calculated in real time according to Coil resistance, separated by judgement
Internal resistance R outL, it is judged that the duty of sensor, due to detection process inductance L and internal resistance RLSeparation calculate be to enter in real time
Row, it is not required to increase extra resource and just can be provided in system real-time BIT monitoring function, high degree reduces complicated journey
Degree, improves reliability and reduces power consumption；By inductance L and internal resistance RLVariation of ambient temperature is avoided to testing result after separation
Impact so that this utility model do not use in-55～+125 DEG C of temperature ranges under any temperature-compensating measure premise obtain
While higher displacement detecting precision, it is provided that in system real time monitoring function (BIT) and accurate quantitative displacement information output
Function.
Accompanying drawing explanation
Fig. 1 is this utility model theory diagram；
Fig. 2 is sensor equivalent circuit model；
Fig. 3 is sensor excitation signal pulse signal schematic diagram；
Fig. 4 is different displacement lower sensor coil single order zero state response curves；
The schematic diagram of the response curve of analog-digital converter sampling when Fig. 5 is 4mm；
The schematic diagram of the response curve of analog-digital converter sampling when Fig. 6 is 6mm.
Detailed description of the invention
The technical solution of the utility model is described further below, but claimed scope is not limited to described.
The testing circuit of a kind of displacement transducer as shown in Figure 1, including impulse generating unit, detector unit, current limliting electricity
Resistance R, sensor internal coil and sample resistance RS, described sensor internal coil is equivalent to internal resistance RLConnect with inductance L, described
Current-limiting resistance R, internal resistance RL, inductance L and sample resistance RSAfter series connection, one end is connected with impulse generating unit, other end ground connection；Described
Detector unit detection sample resistance RSThe voltage at two ends or flow through sample resistance RSElectric current.Described detector unit is analog digital conversion
Device, current sense amplifier, current sensor etc. can will flow through sample resistance RSElectric current or its both end voltage be converted into number
The circuit of word amount.Described impulse generating unit be digital signal processor DSP, single-chip microprocessor MCU, Digital Frequency Synthesize chip DDS,
Programmable logic device (CPLD)/FPGA, risc microcontroller ARM etc. can produce the circuit of pulse signal.
Sensor internal coil equivalent model is as in figure 2 it is shown, by ideal inductance L and internal resistance RLSeries connection and with parasitic capacitance Cp
In parallel and constitute, and parasitic capacitance Cp is the least, can ignore, thus can by sensor internal coil physical model directly etc.
Effect is ideal inductance L and internal resistance RLCascade.Owing to coil uses enamel-covered wire coiling to form, with variation of ambient temperature, paint
The resistivity of envelope curve material changes, and causes Coil resistance RLChange, and winding inductance quantity L by below equation approximate to
Go out:
In formula: N is coil turn；μ0For permeability of vacuum；A is air gap net sectional area；δ is air gap thickness, in formula
Four parameters are the most insensitive to temperature, therefore probe coil inductance value does not changes with variation of ambient temperature.
Described impulse generating unit output pulse buffered circuit output drive signal.
The detection method of the testing circuit of a kind of displacement transducer, comprises the following steps:
(1) use impulse generating unit output drive signal to current-limiting resistance R；Pulse generating circuit is through current-limiting resistance R
Afterwards to sensor internal coil and sample resistance RSThe series loop constituted applies single order excitation.
(2) detector unit sample streams sampled resistance RSElectric current or sample resistance RSThe voltage at two ends.
(3) by flowing through sample resistance RSCurrent value calculate the internal resistance R of sensor internal coilL；Flow through sample resistance RS
Electric current equal to flowing through the electric current of inductance coil, by detection sample resistance RSElectric current can indirect detection flows through sensor coil
Electric current, set up the single order zero state response function of inductance coil, according to the change flowing through coil current under unit interval variable quantity
Change, solve Coil resistance R respectivelyLAnd coil inductance L.
Zero moment i(0+)=i(0-)=0, the response of circuit is zero state response.The electric current flowing through coil and sample resistance is:
Wherein, imFor loop maximum current, τ is time constant.
T, detector unit is to sample resistance RSBoth end voltage carries out sampling and obtains voltage U1, can obtain flowing through sampling electricity
The electric current of resistance is:
After (3～5) individual τ time, exciter response convergence terminates.The electric current flowing through coil reaches maximum im, detection
Unit is again to sample resistance RSBoth end voltage carries out sampling and obtains voltage U2, can obtain flowing through sample resistance RSMaximum current be:
Formula (2), formula (3) and formula (4) are substituted into formula (1), and arrangement obtains
In equation (5), Um、RS, R, t be known quantity, U1、U2Obtained by analog-digital converter sampling, by solving equation be
Available cell winding inductance L and Coil resistance RL.Change identification metal target according to cell winding inductance value L is to passing
The change in displacement of sensor inductive probe.
(4) internal resistance R is setLSpan and the variable quantity distribution of inductance L；The wherein internal resistance R of cell windingL
=enamel-covered wire length l × resistivity of material ρ, the most given enamel-covered wire resistivity is at room temperature 20 DEG C, and enamel-covered wire is made
Cu alloy material temperature coefficient of resistivity α R (20～100 DEG C)=27 × 10-4/ DEG C, along with variations in temperature enamel-covered wire material
Resistivity changes, and causes the internal resistance R of cell windingLChange, may determine that in full temperature according to resistivity of material variable quantity
In the range of degree, interior group of RLSpan is (Rt1～Rt2)。
(5) metal target range sensor sensitive surface change in displacement situation is judged according to the change of the inductance L detected.
When inductance L is more than threshold value Ga set, it is believed that measured target is close；When inductance L is less than threshold value Gd set, it is believed that
Measured target away from.
By formula:
In formula:
L: winding inductance quantity；
N: coil turn；
μ0: permeability of vacuum；
S: effective air gap area；
D: air gap thickness；
RL: coil direct current equivalent resistance；
ρ is coil varnish envelope curve resistivity of material；
L is coil varnish envelope curve length.
Understand, inductance L be the most only relevant to after determining coil turn and effective coil area tested metal target away from
Displacement d from sensor sensing face；After coil turn and coil diameter determine, enamel-covered wire length determines the most therewith, in coil
Resistance RLSize is relevant to resistivity of material ρ influenced by ambient temperature, and this utility model is i.e. according to the change of detection winding inductance quantity L
Change the change determining metal target range sensor sensitive surface displacement d, and real-time judge Coil resistance RLSize judges to pass
The duty (real-time BIT) of sensor.
(6) according to the internal resistance R detectedLValue judge the duty of sensor.Can be real owing to calculating through over-sampling
Time be accurately obtained internal resistance RL, as the R actually obtainedLValue is beyond (Rt1～Rt2) scope, then it is assumed that coil breaks down, particularly as follows:
Work as RLMore than Rt2Time, coil open circuit；Work as RLLess than Rt1Time, coil short.
Embodiment:
With all-metal sealing inductive displacement transducer as example, of the present utility model embodiment it is discussed in detail:
The internal resistance R of nominal coil at this sensor room temperature 20 DEG CLFor (12～14) Ω, when ambient temperature is in (-55～+70)
Between DEG C during change, Coil resistance RLTemperature drift distribution is (10～16) Ω.When target displacement is 4mm, coil nominal electricity
Sensibility reciprocal L isWorking sensor is in proximity state；When metal target displacement is 6mm, winding inductance quantity is relative to 4mm electricity
Sensitivity changes amount is distributed in (80～120) μ H, and working sensor is away from state.
Based on These parameters, it is contemplated that this utility model launches interference and self capacity of resisting disturbance, set coil zero state
Response maximum excitation voltage UmValue is 2V DC, is 47 Ω by current-limiting resistance R value, sample resistance RSValue is 100 Ω, sensing
The maximum through-flow about 12.5mA of device coil.After pumping signal is buffered, output (0～2) V as shown in Figure 3, frequency 500Hz, account for
The empty pulse signal than 20%, encourages in cell winding and sample resistance R after current-limiting resistance R current limlitingSThe series connection constituted is returned
Road, obtains response curve as shown in Figure 4.
Use 12 analog-digital converters to carry out voltage sample, be 4095 to the maximum, respective pulses maximum voltage 2V.
As it is shown in figure 5, when target is away from sensor sensing face 4mm, obtain voltage U at t=25us instance sample1Digital quantity
Being 1407, corresponding voltage value is 687.2mV, terminates post-sampling in response and obtains U2Digital quantity is 2563, and corresponding voltage value is
1.252V, formula (5) Equation for Calculating be given obtains coil inductance L=5.016mH, Coil resistance RL=12.73 Ω.
As shown in Figure 6, when target is away from sensor sensing face 6mm, voltage U is obtained at t=25us instance sample1Digital quantity
Being 1424, corresponding voltage value is 695.5mV, terminates post-sampling in response and obtains U2Digital quantity is 2557, and corresponding voltage value is
1.253V, formula (5) Equation for Calculating be given obtains coil inductance L=4.926mH, Coil resistance RL=12.58 Ω.Relatively
It is 90 μ H in 4mm inductance L variable quantity.
This utility model, by setting up displacement transducer physical model, is built testing circuit and is calculated the most in real time in sensor
Put the internal resistance R of coilL, for the duty of monitoring sensor in real time, and calculate sensors inductance in real time according to Coil resistance
L, it is judged that the positional information of measured target；Due to detection process inductance L and internal resistance RLSeparate calculate carry out in real time, not
Needing to increase extra resource and just can be provided in system real time monitoring function (BIT), high degree reduces complexity in circuits,
Improve reliability and reduce power consumption；By inductance L and internal resistance RLVariation of ambient temperature is avoided to testing result after separation
Impact so that this utility model does not use in-55～+125 DEG C of temperature ranges and obtains relatively under any temperature-compensating measure premise
While high displacement detecting precision, it is provided that in system real time monitoring function (BIT) and accurate quantitative displacement information output work
Energy.
Claims (3)
1. a testing circuit for displacement transducer, built-in including impulse generating unit, detector unit, current-limiting resistance R, sensor
Coil and sample resistance RS, described sensor internal coil is equivalent to internal resistance RLConnect with inductance L, it is characterised in that: described current limliting
Resistance R, internal resistance RL, inductance L and sample resistance RSAfter series connection, one end is connected with impulse generating unit, other end ground connection；Described detection
Unit detection sample resistance RSThe voltage at two ends or flow through sample resistance RSElectric current.
2. the testing circuit of displacement transducer as claimed in claim 1, it is characterised in that: described detector unit is analog digital conversion
Device, current sense amplifier or current sensor.
3. the testing circuit of displacement transducer as claimed in claim 1, it is characterised in that: described impulse generating unit is numeral
Signal processor DSP, single-chip microprocessor MCU, single-chip digital frequency synthesis chip DDS, programmable logic device (CPLD)/FPGA or RISC
Microprocessor ARM.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521002203.0U CN205482768U (en) | 2015-12-07 | 2015-12-07 | Detection circuit for displacement sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201521002203.0U CN205482768U (en) | 2015-12-07 | 2015-12-07 | Detection circuit for displacement sensor |
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| CN205482768U true CN205482768U (en) | 2016-08-17 |
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| CN201521002203.0U Expired - Fee Related CN205482768U (en) | 2015-12-07 | 2015-12-07 | Detection circuit for displacement sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105387796A (en) * | 2015-12-07 | 2016-03-09 | 贵州新安航空机械有限责任公司 | Detection circuit of induction type displacement sensor and detection method of detection circuit |
| CN106404034A (en) * | 2016-08-21 | 2017-02-15 | 陕西华燕航空仪表有限公司 | Eddy-current-type proximity-sensor online self-checking method and self-checking circuit |
| CN110470205A (en) * | 2019-08-13 | 2019-11-19 | 森泰英格（成都）数控刀具股份有限公司 | The method of passive coil induction detection automatic identification knife handle |
-
2015
- 2015-12-07 CN CN201521002203.0U patent/CN205482768U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105387796A (en) * | 2015-12-07 | 2016-03-09 | 贵州新安航空机械有限责任公司 | Detection circuit of induction type displacement sensor and detection method of detection circuit |
| CN105387796B (en) * | 2015-12-07 | 2017-12-22 | 贵州新安航空机械有限责任公司 | The detection circuit and its detection method of a kind of inductive displacement transducer |
| CN106404034A (en) * | 2016-08-21 | 2017-02-15 | 陕西华燕航空仪表有限公司 | Eddy-current-type proximity-sensor online self-checking method and self-checking circuit |
| CN106404034B (en) * | 2016-08-21 | 2019-11-29 | 陕西华燕航空仪表有限公司 | A kind of electric vortex type proximity sensor On-line self-diagnosis method and self-checking circuit |
| CN110470205A (en) * | 2019-08-13 | 2019-11-19 | 森泰英格（成都）数控刀具股份有限公司 | The method of passive coil induction detection automatic identification knife handle |
| CN110470205B (en) * | 2019-08-13 | 2021-07-09 | 森泰英格（成都）数控刀具股份有限公司 | Method for automatically identifying knife handle through passive coil induction detection |
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|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160817 Termination date: 20191207 |
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| CF01 | Termination of patent right due to non-payment of annual fee |