CN108955933A - A kind of measuring circuit and parameter selection method improving rail temperature measurement accuracy - Google Patents
A kind of measuring circuit and parameter selection method improving rail temperature measurement accuracy Download PDFInfo
- Publication number
- CN108955933A CN108955933A CN201810930631.1A CN201810930631A CN108955933A CN 108955933 A CN108955933 A CN 108955933A CN 201810930631 A CN201810930631 A CN 201810930631A CN 108955933 A CN108955933 A CN 108955933A
- Authority
- CN
- China
- Prior art keywords
- circuit
- resistance
- operational amplification
- thermal resistance
- connection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
- G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
The invention discloses a kind of measuring circuits and parameter selection method for improving rail temperature measurement accuracy, circuit includes: that three output ends of three output thermal resistance R are respectively provided with lead resistance r1, r2 and r3, three-wire system bridge circuit includes resistance R1, R2, R3 and R4 of annular connection, the wherein points of common connection ground connection of points of common connection connection the reference power source E, R3 and R4 of R1 and R2；The end A of three output thermal resistance R is connect by r1 with R1, and the end A of three output thermal resistance R also passes through r2 and the positive input terminal of operational amplification circuit connects, and the end B of three output thermal resistance R is connect by r3 with R4；The points of common connection of R2 and R3 is also connect with the negative input end of operational amplification circuit.The present invention does not need the value of measurement sensor lead and contact resistance, can greatly reduce lead and contact resistance bring measurement error, promotes the precision, stability and anti-interference ability of Acquisition Circuit, also simplifies in-site installation process.
Description
Technical field
The present invention relates to field of rail detection more particularly to a kind of measuring circuits and ginseng for improving rail temperature measurement accuracy
Number choosing method.
Background technique
Railway Environment situation is complicated, wireless solution limited by Railway Environment (mounting means --- may cause driving and pacify
Full problem, wireless transmission --- interference, train shielding interference are more on railway, and power supply --- railway electricity is special line, and waterproof is dust-proof
Etc.), therefore the mode that sensor is mutually separated with acquisition equipment is generallyd use, sensor is fixed on rail with fixture, is acquired
Equipment is mounted on by railway outside safe distance, can make acquisition system and railway track electrical isolation in this way, and guarantee will not be because of
The factors such as sensor falls off, electromagnetic interference bring harm to railway operation.
However, in the above-mentioned framework separated using usual sensor with acquisition equipment, sensor lead when due to installation
Length thickness this be that site operation determines that and resistance brought by the length thickness of lead is inconsistent, this results in temperature
The reduction of measurement accuracy.Longer sensor lead and contact impedance can bring biggish error to measurement, while compared with long lead
Also environmental disturbances can be allowed more significant.Specifically, the resistance of lead can directly result in the overall offset of measurement temperature, due to lead
The resistance value of resistance is uncertain, so the overall offset of measurement temperature is also just uncertain, it is as a result exactly measurement accuracy reduction.
After the traditional measurement method of the prior art is direct measurement, then lead and the corresponding temperature value of contact resistance are subtracted,
This mode must all measure lead and contact resistance value in each installation, and execute-in-place is very inconvenient, and be easy to be measured
The precision of instrument and the supervisor of survey crew, which realize, to be influenced, and causes measurement error huge.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide a kind of measurements for improving rail temperature measurement accuracy
Circuit and parameter selection method solve the prior art.
The purpose of the present invention is achieved through the following technical solutions: a kind of measurement improving rail temperature measurement accuracy
Circuit, including three output thermal resistance R, three-wire system bridge circuit and operational amplification circuit；
Three output ends of the three output thermal resistance R are respectively provided with lead resistance r1, r2 and r3, the three-wire system
Bridge circuit includes resistance R1, R2, R3 and R4 of annular connection, and wherein the points of common connection of R1 and R2 connects reference power source E, R3
It is grounded with the points of common connection of R4；Wherein, R2=R3, and when three-wire system bridge circuit balance, (R1+r1+r2)·R3=(R4
+r2+r3+R)·R2；
The end A of three output thermal resistance R is connect by r1 with R1, and the end A of three output thermal resistance R also passes through r2 and operation amplifier
The positive input terminal of circuit connects, and the end B of three output thermal resistance R is connect by r3 with R4；The points of common connection of R2 and R3 also with fortune
Calculate the negative input end connection of amplifying circuit；
The output end of operational amplification circuit exports measuring signal.
Further, the model PT100 of the three output thermal resistance R.
Further, described lead resistance r1, r2 and r3 are equal in magnitude.
Further, the measuring circuit further includes common-mode signal suppression circuit, for the common-mode signal production to input
Raw filtering inhibiting effect；The common-mode signal suppression circuit includes the positive input terminal and negative input for being connected to operational amplification circuit
Capacitor C1 between end.
Further, the measuring circuit further include be respectively arranged at operational amplification circuit positive input terminal it is first low
Bandpass filter circuit and be set to operational amplification circuit negative input end the second low-pass filter circuit.
Further, first low-pass filter circuit includes R5, C2 and C4, and wherein one end of R5 is connect with r2, R5
Other end connect respectively with one end of the positive input terminal of operational amplification circuit, one end of C2, C4, the other end and C4 of C2
Other end ground connection；Second low-pass filter circuit includes R6, C3, C5, and wherein one end of R6 connects with R2 and R3 respectively
It connecing, the other end of R6 is connect with one end of the negative input end of operational amplification circuit, one end of C3, C5 respectively, and other the one of C3
The other end of end and C5 are grounded.
The present invention also provides a kind of parameter selection method of the measuring circuit of raising rail temperature measurement accuracy, packets
Include following steps:
S1: it determines the range of the rail temperature of actual needs measurement, and determines three output thermal resistance R's according to the range
Resistance value range；
S2: according to the complexity for the resistance value for finding actual resistance and consider centainly fault-tolerant, select basic point, obtain and exist
The resistance value size of three output thermal resistance R when basic point；Wherein when being in basic point, the three-wire system bridge circuit is in equilibrium-like
State；
S3: according to R2=R3With (the R when three-wire system bridge circuit balances1+r1+r2)·R3=(R4+r2+r3+R)·R2's
The versatile smart resistance that condition, the actual size of lead resistance r1, r2 and r3 and consideration can be bought, carries out three-wire system
The selection of bridge circuit resistance sizes: the size of R2 and R3 is chosen first, and according to the resistance value of the three output thermal resistance R in basic point
The size of size selection resistance R1 and R4；
S4: it according to the size of resistance R1, R2, R3 and R4 of selection, obtains maximum in the range of the rail temperature at this time
The voltage swing of the input terminal of operational amplification circuit when value and/or minimum value；
S5: according to the sample range of subsequent A/D converter circuit, the amplification factor of operational amplification circuit is determined.
Further, the method further include:
S6: considering the low-pass filtering bandwidth range of operational amplification circuit input end signal input, and selection is set to operation and puts
The parameter of the low-pass filter circuit of big circuit input end.
Further, the method further include:
S7: the parameter for the elimination common-mode signal capacitor being set between two input terminals of operational amplification circuit is chosen.
Further, it is generally the case that described lead resistance r1, r2 and the r3 is equal in magnitude, therefore in step s3 without
The actual size of lead resistance r1, r2 and r3 need to be obtained.
The beneficial effects of the present invention are:
(1) present invention uses the horizontal bridge circuit of three-wire system, does not need the value of measurement sensor lead and contact resistance,
In the case of specific circuit parameter, lead and contact resistance bring measurement error can be greatly reduced, promotes Acquisition Circuit
Precision, stability and anti-interference ability, also simplify in-site installation process.
(2) circuit structure of the invention can be eliminated or be substantially reduced and influence brought by sensor lead resistance, and
And the particular electrical circuit parameter performance in work-in parameters choosing method can be more preferable, (needs basis without using the compensation resistance of periphery
The installation requirements at scene are adjusted) it compensates to eliminate the influence of sensor lead resistance.
(3) parameter selection method of the invention, so that the present invention is used exclusively for adjusting the circuit of zero point and full scale, by
Circuit parameter is assured that, when a circuit is after application environment and technical indicator determine, circuit parameter determines that.And show
Have technology need according to the actual situation on site (for example, by using the lead of different length thicknesses), need to adjust compensation resistance to
Eliminate lead error.
(4) present invention has filtering inhibiting effect (capacitor C1 inhibits common-mode signal) to input common-mode signal, and to input
AC signal has filtering inhibiting effect, and (R5, C2, C4 play low-pass filtering to amplifier positive input terminal signal, and R6, C3, C5 are negative to amplifier
Input end signal plays low-pass filtering).
(5) device needed for is few, at low cost, circuit be welded after there is no need to have adjusted, can direct batch application.
Detailed description of the invention
Fig. 1 is circuit connection diagram of the present invention；
Fig. 2 is horizontal electric bridge schematic diagram.
Specific embodiment
Technical solution of the present invention is clearly and completely described with reference to the accompanying drawing, it is clear that described embodiment
It is a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill people
Member's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that belong to "center", "upper", "lower", "left", "right", "vertical",
The direction of the instructions such as "horizontal", "inner", "outside" or positional relationship be based on direction or positional relationship described in attached drawing, merely to
Convenient for description the present invention and simplify description, rather than the device or element of indication or suggestion meaning must have a particular orientation,
It is constructed and operated in a specific orientation, therefore is not considered as limiting the invention.In addition, belonging to " first ", " second " only
For descriptive purposes, it is not understood to indicate or imply relative importance.
In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, belong to " installation ", " phase
Even ", " connection " shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or be integrally connected；It can
To be mechanical connection, it is also possible to be electrically connected；It can be directly connected, can also can be indirectly connected through an intermediary
Connection inside two elements.For the ordinary skill in the art, above-mentioned term can be understood at this with concrete condition
Concrete meaning in invention.
As long as in addition, the non-structure each other of technical characteristic involved in invention described below different embodiments
It can be combined with each other at conflict.
Embodiment 1
A kind of measuring circuit improving rail temperature measurement accuracy, the circuit are used to measure rail iron by wired mode
Three output thermal resistance R of the temperature data of rail, the measuring circuit are held on rail, and rest part passes through measurement route.Specifically
Ground, as shown in Figure 1, a kind of measuring circuit for improving rail temperature measurement accuracy includes three output thermal resistance R, three-wire system electric bridge electricity
Road and operational amplification circuit；Three output ends of the three output thermal resistance R are respectively provided with lead resistance r1, r2 and r3, institute
The three-wire system bridge circuit stated includes resistance R1, R2, R3 and R4 of annular connection, and wherein the points of common connection of R1 and R2 connects ginseng
Examine the points of common connection ground connection of power supply E, R3 and R4；Wherein, R2=R3, and when three-wire system bridge circuit balance, (R1+r1+
r2)·R3=(R4+r2+r3+R)·R2；The end A of three output thermal resistance R is connect by r1 with R1, and the end A of three output thermal resistance R is also
It is connected by the positive input terminal of r2 and operational amplification circuit, the end B of three output thermal resistance R is connect by r3 with R4；R2's and R3
Points of common connection is also connect with the negative input end of operational amplification circuit；The output end of operational amplification circuit exports measuring signal.
In the prior art, after the traditional measurement method of the prior art is direct measurement, then lead and contact resistance are subtracted
Corresponding temperature value, this mode must all measure lead and contact resistance value in each installation, and execute-in-place is very inconvenient, and
Being easy to be realized by the precision of measuring instrument and the supervisor of survey crew influences, and causes measurement error huge.
And in the present embodiment, using the horizontal bridge circuit of three-wire system, do not need measurement sensor lead and contact resistance
Value can greatly reduce lead and contact resistance bring measurement error in specific circuit parameter, promotion is adopted
Precision, stability and the anti-interference ability of collector, also simplify in-site installation process.
Specifically, following the description limits the model PT100 of the three output thermal resistance R, remaining may be implemented three defeated
Thermal resistance R may be incorporated for replacing out.
Horizontal electric bridge belongs to one kind of unbalanced electric bridge, as shown in Fig. 2, R1=RX、R2=R3, and R1≠R2, electric at this time
Bridge balance, exports pressure difference U0It is 0.
Unbalanced electric bridge usually has voltage output and power output both of which.In acquisition system, since electric bridge is defeated
The impedance that outlet accesses device is all higher, so generally using voltage output mode.
It can be obtained by Fig. 2, in the case where bridge output access device input impedance levels off to infinite:
Enable RX=RX0+ Δ R, RXFor measured resistance, RX0For its initial value, Δ R is its resistance change, can by formula (1)
To obtain:
For horizontal electric bridge, formula (2) can be simplified are as follows:
It can be obtained by formula (3), work as RX0When sufficiently large, output voltage values U0It is in a linear relationship with resistance change Δ R.
And accordingly, the present embodiment is using the horizontal bridge circuit of three-wire system described in Fig. 1.When bridge balance, (R1
+r1+r2)·R3=(R4+r2+r3+RPT100)·R2, wherein r1、r2、r3For PT100 sensor lead, and in r1=r2=r3=r
In the case where (usual situation), from the characteristic of horizontal electric bridge: R1=R4+RPT100=RX。
Then export horizontal bridge output voltage are as follows:
Resistance delta Δ R is introduced, can be obtained by formula (4):
Wherein, RX0=R1=(R4The reference resistance of+PT100), the reference resistance of PT100 is selected according to practical situations
It takes.
It can be obtained by formula (5), work as RX0When value is larger, Δ R resistance change is smaller, (r refers to sensing lead resistance r
Device single ended leads impedance, it is 2r that sensor both ends lead, which brings impedance into, in practical application) there will not be too big shadow to output voltage
Ring (in practical applications, usual r does not exceed 3 Ω under extreme case less than 1 Ω).
Furthermore it is preferred that as shown in Figure 1, in the present embodiment, the measuring circuit further includes that common-mode signal inhibits electricity
Road, for generating filtering inhibiting effect to the common-mode signal of input；The common-mode signal suppression circuit includes being connected to operation
Capacitor C1 between the positive input terminal and negative input end of amplifying circuit.
It is preferred that as shown in Figure 1, in the present embodiment, the measuring circuit further includes being respectively arranged at operation
First low-pass filter circuit of the positive input terminal of amplifying circuit and be set to operational amplification circuit negative input end it is second low
Bandpass filter circuit.
Specifically, as shown in Figure 1, first low-pass filter circuit includes R5, C2 and C4, wherein one end of R5 and r2
Connection, the other end of R5 are connect with one end of the positive input terminal of operational amplification circuit, one end of C2, C4 respectively, and C2 is in addition
The other end of one end and C4 ground connection；Second low-pass filter circuit includes R6, C3, C5, wherein one end of R6 respectively with
R2 is connected with R3, and the other end of R6 is connect with one end of the negative input end of operational amplification circuit, one end of C3, C5 respectively, C3
Other end and C5 other end ground connection.
Embodiment 2
Realization based on the above embodiment, the present embodiment also provide a kind of survey of raising rail temperature measurement accuracy
The parameter selection method of circuit is measured, this method is for selecting the value of each component in above-mentioned measuring circuit.Including with
Lower step:
S1: it determines the range of the rail temperature of actual needs measurement, and determines three output thermal resistance R's according to the range
Resistance value range.
Specifically, in the present embodiment, the range of rail temperature is at -40 DEG C~+100 DEG C.
Wherein, the minimum temperature point of usually measurement temperature is known as the zero point (AD of corresponding operational amplification circuit output end connection
The minimum voltage of sample range), maximum temperature point is known as full scale (the AD sample range of corresponding operational amplification circuit output end connection
Ceiling voltage).But in actually reference, to promote precision, it will usually which there are certain surpluses.For example, AD sample range be 0~
4.5V, then practical zero point can be located at 0.1V or so, 4.4V or so can be arranged in full scale.
When the range of rail temperature is at -40 DEG C~+100 DEG C, corresponding PT100 resistance value is the Ω of 84.27 Ω~138.51.
S2: according to the complexity for the resistance value for finding actual resistance and consider centainly fault-tolerant, basic point is scheduled on smaller
At the stated range minimum of the rail temperature, the resistance value size of the three output thermal resistance R in basic point is obtained；Wherein when in base
When point, the three-wire system bridge circuit is in equilibrium state.
Therefore in the present embodiment, -43 DEG C of corresponding 83.08 Ω of resistance value are chosen as basic point.
According to the formula (5) and follow-up test data provided from embodiment 1 it is found that error theory is 0 in basic point, from
Base point temperature is remoter, and accumulated error is bigger.So to be located at -40 DEG C of corresponding 84.27 Ω most ideal for basic point, but actually it is difficult to look for
To the resistance of this resistance value, and consider certain error tolerance, therefore basic point is scheduled on -43 DEG C.
And if by basic point choice in measurement temperature range central point, the measured temperature at central point both ends has accumulation
Error, but compared with basic point is located at one end, accumulated error will reduce half, and amplifier rear end needs to add off-centre circuit or direct
Select the AD converter that can sample positive and negative values.
S3: according to R2=R3With (the R when three-wire system bridge circuit balances1+r1+r2)·R3=(R4+r2+r3+R)·R2's
The versatile smart resistance that condition, the actual size of lead resistance r1, r2 and r3 and consideration can be bought, carries out three-wire system
The selection of bridge circuit resistance sizes: the size of R2 and R3 is chosen first, and according to the resistance value of the three output thermal resistance R in basic point
The size of size selection resistance R1 and R4.
Specifically, because being horizontal electric bridge R2=R3, R1+r1=R4+r3+PT100, in order to reduce circuit band itself
The error come, the value of R2 and the value of R1+r1 are unable to that difference is too big, and consider the versatile smart resistance that can be bought, therefore select
Take R2=R3=1k Ω.
And for the size of resistance R1 and R4, choose R1=825 Ω, R4=908 Ω, such R4-R1=908 Ω -825 Ω
=83 Ω, the resistance value (PT100 is 83.08 Ω in -43 DEG C of corresponding resistance values) of PT100 when just corresponding to -43 DEG C of basic point,
When basic point, electric bridge is in equilibrium state, and error zero, as the resistance value of PT100 becomes larger (i.e. temperature raising), electric bridge is in non-flat
Weighing apparatus state, cumulative errors can be also gradually increased, and be that (theories integration that error is gradually increased is formula to error maximum at 100 DEG C
(5))。
When basic point is selected, after circuit parameter is selected, entire circuit volume zero point is also just fixed, does not need to adjust again.
S4: it according to the size of resistance R1, R2, R3 and R4 of selection, obtains maximum in the range of the rail temperature at this time
The voltage swing of the input terminal of operational amplification circuit when value.
Output voltage (being 100 DEG C herein) when obtaining bridge measurement maximum temperature, in the present embodiment, bridge measurement is most
Output voltage is 0.0725V when high-temperature.
S5: according to the sample range of subsequent A/D converter circuit, the amplification factor of operational amplification circuit is determined.
After zero point determines, output voltage (being 100 DEG C herein) × amplifier is amplified when full scale=bridge measurement maximum temperature
Multiple, output voltage is 0.0725V × amplifier amplification factor 62=4.495V when bridge measurement maximum temperature, meets AD converter
The voltage sample range of 0~4.5V, so directly giving amplification factor 62.
Since operational amplification circuit belongs to the prior art, its structure is not repeated.
More preferably, in the present embodiment, the method further include:
S6: considering the low-pass filtering bandwidth range of operational amplification circuit input end signal input, and selection is set to operation and puts
The parameter of the low-pass filter circuit of big circuit input end.
For the first low-pass filter circuit and the second low-pass filter circuit of preferred embodiment in embodiment 1, R5, R6, C2,
The value of C3, C4, C5 choose the main low-pass filtering bandwidth range for considering the input of amplifier input end signal, choose R5=R6=10k
Ω, C2=C3=0.1uF, C4=C5=4.7Uf, mainly since temperature is slow variation, corresponding voltage signal is more steady, institute
Will have inhibition to AC signal.
More preferably, in the present embodiment, the method further include:
S7: the parameter for the elimination common-mode signal capacitor being set between two input terminals of operational amplification circuit is chosen.
And C1=0.001uF is general elimination common-mode signal capacitor.
More preferably, in the present embodiment, it is generally the case that described lead resistance r1, r2 and the r3 is equal in magnitude, therefore
It is not necessarily to obtain the actual size of lead resistance r1, r2 and r3 in step S3.
According to the above parameter, (sensor single-ended resistive r < 1 Ω, when 0.2 square of 10 meters of length of copper wire in practical applications
About 0.86 Ω of resistance), less than 0.2 DEG C of measurement accuracy (having corresponding data in book of telling somebody what one's real intentions are) has been able to meet practical application.
In addition, in order to guarantee measurement accuracy and anti-interference ability, can according to actual application environment in the following ways into
One step promotes circuit performance:
(1)R1And R2Value difference it is not small as far as possible, can guarantee that electric bridge two-arm impedance is consistent in this way, to power supply and external disturbance
Anti-performance access great promotion.
(2)R1Value choose it is suitable, it is too small not only to increase circuit power consumption, but also increase the accumulated error of measurement；Too
The measurement accumulated error of circuit can be reduced greatly, but rear end amplifier amplification factor increases, single-stage amplification is difficult to meet the requirements, and needs
Multistage amplifier circuit, while can also bring the noise of circuit itself into.
(3) OP amplifier in rear end can use instrument amplifier according to specific requirements, further promote the anti-interference of circuit
Ability.Reference power source E can further promote the stability and precision of temperature acquisition access using high-precision reference power source.
(4) temperature measurement range is reduced, accumulated error can be reduced.Thus thought can be by R1Change high-precision number electricity into
Position device, divides temperature section that basic point is arranged, and improving measurement accuracy reduces accumulated error.
(5) by basic point choice in measurement temperature range central point, the measured temperature at central point both ends has accumulation and misses
Difference, but compared with basic point is located at one end, accumulated error will reduce half, and amplifier rear end needs to add off-centre circuit or directly choosing
With the AD converter that can sample positive and negative values.
Embodiment 3
The present embodiment has built corresponding measuring circuit according to the parameter selected in embodiment 2, and obtains to data,
Specifically:
The usual measurement range of rail temperature at -40 DEG C~+100 DEG C, corresponding PT100 resistance value be 84.27 Ω~
138.51 Ω choose -43 DEG C of corresponding 83.08 Ω of resistance value as basic point, and in this, electric bridge is in balance.Enable wherein R1
=825 Ω, R2=R3=1k Ω, R4=908 Ω, R5=R6=10k Ω, C1=0.001uF, C2=C3=0.1uF, C4=C5=
4.7uF, reference power source E=5V, AD converter digit is 16, sampled voltage range is 4.5V.It can according to formula (3), (5)
, horizontal electric bridge output voltage values U0It is as shown in the table:
| Temperature (DEG C) | R=0 Ω | R=0.25 Ω | R=0.5 Ω | R=1 Ω | R=3 Ω | R=5 Ω |
| -40 | 0.00055 | 0.00055 | 0.00055 | 0.00055 | 0.00055 | 0.00055 |
| 20 | 0.01081 | 0.01081 | 0.01081 | 0.01080 | 0.01078 | 0.01076 |
| 0 | 0.02147 | 0.02146 | 0.02146 | 0.02145 | 0.02140 | 0.02135 |
| 20 | 0.03196 | 0.03196 | 0.03195 | 0.03193 | 0.03186 | 0.03179 |
| 40 | 0.04232 | 0.04231 | 0.04230 | 0.04227 | 0.04218 | 0.04209 |
| 60 | 0.05252 | 0.05251 | 0.05249 | 0.05246 | 0.05235 | 0.05224 |
| 80 | 0.06259 | 0.06257 | 0.06255 | 0.06252 | 0.06239 | 0.06225 |
| 100 | 0.07250 | 0.07248 | 0.07247 | 0.07243 | 0.07227 | 0.07212 |
The horizontal electric bridge output voltage values U of table 1-0
By horizontal bridge output voltage U0It is amplified in the effective acquisition voltage range of AD converter by amplifier OP, U
=KU0, wherein K is amplifier amplification factor.According to parameter above, K=62 here.Then the value of AD converter collection voltages U is such as
Shown in following table:
| Temperature (DEG C) | R=0 Ω | R=0.25 Ω | R=0.5 Ω | R=1 Ω | R=3 Ω | R=5 Ω |
| -40 | 0.034 | 0.034 | 0.034 | 0.034 | 0.034 | 0.034 |
| 20 | 0.671 | 0.670 | 0.670 | 0.670 | 0.668 | 0.667 |
| 0 | 1.331 | 1.331 | 1.330 | 1.330 | 1.327 | 1.324 |
| 20 | 1.982 | 1.981 | 1.981 | 1.980 | 1.975 | 1.971 |
| 40 | 2.624 | 2.623 | 2.622 | 2.621 | 2.615 | 2.610 |
| 60 | 3.256 | 3.255 | 3.255 | 3.253 | 3.246 | 3.239 |
| 80 | 3.880 | 3.879 | 3.878 | 3.876 | 3.868 | 3.860 |
| 100 | 4.495 | 4.494 | 4.493 | 4.490 | 4.481 | 4.471 |
Table 2-AD converter collection voltages value U
Can be obtained by Tables 1 and 2: in the case where lead impedance is constant, with the raising of measurement temperature, measurement error is gradually
Increase；And in the case where temperature-resistant, lead impedance is gradually increased, and measurement error is gradually increased.
Therefore, in 100 DEG C far from basic point (i.e. bridge balance point), the error of measurement is maximum；At 0 DEG C of close basic point
When, measurement error very little is close to zero.
After the value of AD converter collection voltages U is quantified by AD and it is converted into corresponding temperature value T, as a result such as following table institute
Show:
| 100℃ | R=0 Ω | R=0.25 Ω | R=0.5 Ω | R=1 Ω | R=3 Ω | R=5 Ω |
| AD value (16bit) | 65463 | 65449 | 65434 | 65390 | 65259 | 65113 |
| T(℃) | 100.00 | 99.97 | 99.94 | 99.84 | 99.55 | 99.23 |
| ΔT(℃) | 0 | 0.03 | 0.06 | 0.16 | 0.45 | 0.77 |
| T(℃) | 0 | 1.25 | 2.5 | 5 | 15 | 25 |
The corresponding temperature value T of table 3- conversion
In table 3, Δ T is indicated to bring lead resistance into and is not brought between lead resistance the difference for measuring temperature, T intorIt indicates
(in -40 DEG C~+100 DEG C temperature sections, 0.4 Ω is close for sensor double end and the corresponding temperature value of contact resistance when directly measuring
Like 1 DEG C corresponding).
Therefore it can be obtained by table 3, using circuit structure provided by the above embodiment and circuit parameter, (r < 1 in general
Ω), the worst error of measurement is no more than 0.2 DEG C, and in the limiting case (Ω of r < 3), measurement worst error is not more than 0.5
℃.The temperature value T introduced with conducting wire when directly measuring and contact resistancerIt compares, measurement error greatly reduces.
Obviously, the above embodiments are merely examples for clarifying the description, and does not limit the embodiments, right
For those of ordinary skill in the art, can also make on the basis of the above description other it is various forms of variation or
It changes.There is no necessity and possibility to exhaust all the enbodiments.And thus amplify out it is obvious variation or
It changes still within the protection scope of the invention.
Claims (10)
1. a kind of measuring circuit for improving rail temperature measurement accuracy, it is characterised in that: including three output thermal resistance R, three-wire system
Bridge circuit and operational amplification circuit；
Three output ends of the three output thermal resistance R are respectively provided with lead resistance r1, r2 and r3, the three-wire system electric bridge
Circuit includes resistance R1, R2, R3 and R4 of annular connection, and wherein the points of common connection of R1 and R2 connects reference power source E, R3 and R4
Points of common connection ground connection；Wherein, R2=R3, and when three-wire system bridge circuit balance, (R1+r1+r2)·R3=(R4+r2+
r3+R)·R2；
The end A of three output thermal resistance R is connect by r1 with R1, and the end A of three output thermal resistance R also passes through r2 and operational amplification circuit
Positive input terminal connection, the ends B of three output thermal resistance R are connect by r3 with R4；The points of common connection of R2 and R3 is also put with operation
The negative input end connection of big circuit；
The output end of operational amplification circuit exports measuring signal.
2. a kind of measuring circuit for improving rail temperature measurement accuracy according to claim 1, it is characterised in that: described
The model PT100 of three output thermal resistance R.
3. a kind of measuring circuit for improving rail temperature measurement accuracy according to claim 1, it is characterised in that: described
Lead resistance r1, r2 and r3 are equal in magnitude.
4. a kind of measuring circuit for improving rail temperature measurement accuracy according to claim 1, it is characterised in that: described
Measuring circuit further includes common-mode signal suppression circuit, for generating filtering inhibiting effect to the common-mode signal of input；Described is total to
Mould signal suppression circuit includes the capacitor C1 being connected between the positive input terminal of operational amplification circuit and negative input end.
5. a kind of measuring circuit for improving rail temperature measurement accuracy according to claim 1, it is characterised in that: described
Measuring circuit further includes being respectively arranged at the first low-pass filter circuit of the positive input terminal of operational amplification circuit and being set to fortune
Calculate the second low-pass filter circuit of the negative input end of amplifying circuit.
6. a kind of measuring circuit for improving rail temperature measurement accuracy according to claim 5, it is characterised in that: described
First low-pass filter circuit includes R5, C2 and C4, and wherein one end of R5 is connect with r2, the other end of R5 respectively with operation amplifier
One end connection of the positive input terminal of circuit, one end of C2, C4, the other end of C2 and the other end ground connection of C4；Described
Two low-pass filter circuits include R6, C3, C5, and wherein one end of R6 is connect with R2 and R3 respectively, the other end of R6 respectively with fortune
Calculate one end connection of the negative input end of amplifying circuit, one end of C3, C5, the other end of C3 and the other end ground connection of C5.
7. a kind of parameter of the measuring circuit of raising rail temperature measurement accuracy as described in any one of claim 1~6
Choosing method, it is characterised in that: the following steps are included:
S1: determining the range of the rail temperature of actual needs measurement, and the resistance of three output thermal resistance R is determined according to the range
It is worth range；
S2: according to the complexity for the resistance value for finding actual resistance and consider centainly fault-tolerant, select basic point, obtain in basic point
When three output thermal resistance R resistance value size；Wherein when being in basic point, the three-wire system bridge circuit is in equilibrium state；
S3: according to R2=R3With (the R when three-wire system bridge circuit balances1+r1+r2)·R3=(R4+r2+r3+R)·R2Condition,
The versatile smart resistance that the actual size of lead resistance r1, r2 and r3 and consideration can be bought carries out three-wire system electric bridge electricity
The selection of road resistance sizes: the size of R2 and R3 is chosen first, and is selected according to the resistance value size of the three output thermal resistance R in basic point
Take the size of resistance R1 and R4；
S4: according to the size of resistance R1, R2, R3 and R4 of selection, obtain at this time the range maximum value of the rail temperature and/
Or when minimum value the input terminal of operational amplification circuit voltage swing；
S5: according to the sample range of subsequent A/D converter circuit, the amplification factor of operational amplification circuit is determined.
8. parameter selection method according to claim 7, it is characterised in that: the method further include:
S6: considering the low-pass filtering bandwidth range of operational amplification circuit input end signal input, and selection is set to operation amplifier electricity
The parameter of the low-pass filter circuit of road input terminal.
9. parameter selection method according to claim 7, it is characterised in that: the method further include:
S7: the parameter for the elimination common-mode signal capacitor being set between two input terminals of operational amplification circuit is chosen.
10. parameter selection method according to claim 7, it is characterised in that: under normal conditions, the lead resistance
R1, r2 and r3 are equal in magnitude, therefore are not necessarily to obtain the actual size of lead resistance r1, r2 and r3 in step s3；And in order to
Circuit bring error itself is reduced, it is too big that the value of R2 and the value of R1+r1 are unable to difference.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810930631.1A CN108955933B (en) | 2018-08-15 | 2018-08-15 | Measuring circuit for improving temperature measurement precision of steel rail and parameter selection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810930631.1A CN108955933B (en) | 2018-08-15 | 2018-08-15 | Measuring circuit for improving temperature measurement precision of steel rail and parameter selection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108955933A true CN108955933A (en) | 2018-12-07 |
| CN108955933B CN108955933B (en) | 2021-06-04 |
Family
ID=64470385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810930631.1A Active CN108955933B (en) | 2018-08-15 | 2018-08-15 | Measuring circuit for improving temperature measurement precision of steel rail and parameter selection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108955933B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113176004A (en) * | 2021-04-26 | 2021-07-27 | 精进电动科技股份有限公司 | Temperature measurement circuit and motor controller |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2692646Y (en) * | 2003-09-29 | 2005-04-13 | 中兴通讯股份有限公司 | Thermoresistor temp measuring circuit |
| CN202748160U (en) * | 2012-08-24 | 2013-02-20 | 石家庄国耀电子科技有限公司 | Anti-interference temperature sampling circuit |
| CN203224306U (en) * | 2013-01-16 | 2013-10-02 | 燕山大学 | Single-chip microcomputer control-based intelligent flat-panel acquisition system for thermal electromotive force |
| CN104344908A (en) * | 2013-08-02 | 2015-02-11 | 上海微电子装备有限公司 | Three-wire-system thermal resistor measuring circuit |
| CN204270093U (en) * | 2014-09-12 | 2015-04-15 | 株洲电力机车厂长河机电产品开发公司 | A kind of temperature monitor |
| CN204575212U (en) * | 2015-04-14 | 2015-08-19 | 中国广州分析测试中心 | A kind of electric thermo-couple temperature metering circuit |
| CN105371976A (en) * | 2014-08-20 | 2016-03-02 | 哈尔滨理大晟源科技开发有限公司 | Thermal resistance temperature measuring device and temperature measuring method |
| CN106872173A (en) * | 2017-04-28 | 2017-06-20 | 北京新能源汽车股份有限公司 | A kind of motor temperature sampling circuit fault detection method and detection circuit |
| CN207472443U (en) * | 2017-12-05 | 2018-06-08 | 深圳市康必达控制技术有限公司 | Multichannel three-wire system resistance temperature measurement circuit |
-
2018
- 2018-08-15 CN CN201810930631.1A patent/CN108955933B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2692646Y (en) * | 2003-09-29 | 2005-04-13 | 中兴通讯股份有限公司 | Thermoresistor temp measuring circuit |
| CN202748160U (en) * | 2012-08-24 | 2013-02-20 | 石家庄国耀电子科技有限公司 | Anti-interference temperature sampling circuit |
| CN203224306U (en) * | 2013-01-16 | 2013-10-02 | 燕山大学 | Single-chip microcomputer control-based intelligent flat-panel acquisition system for thermal electromotive force |
| CN104344908A (en) * | 2013-08-02 | 2015-02-11 | 上海微电子装备有限公司 | Three-wire-system thermal resistor measuring circuit |
| CN105371976A (en) * | 2014-08-20 | 2016-03-02 | 哈尔滨理大晟源科技开发有限公司 | Thermal resistance temperature measuring device and temperature measuring method |
| CN204270093U (en) * | 2014-09-12 | 2015-04-15 | 株洲电力机车厂长河机电产品开发公司 | A kind of temperature monitor |
| CN204575212U (en) * | 2015-04-14 | 2015-08-19 | 中国广州分析测试中心 | A kind of electric thermo-couple temperature metering circuit |
| CN106872173A (en) * | 2017-04-28 | 2017-06-20 | 北京新能源汽车股份有限公司 | A kind of motor temperature sampling circuit fault detection method and detection circuit |
| CN207472443U (en) * | 2017-12-05 | 2018-06-08 | 深圳市康必达控制技术有限公司 | Multichannel three-wire system resistance temperature measurement circuit |
Non-Patent Citations (2)
| Title |
|---|
| 任殿慧等: "一种铂电阻测温电路的非线性校正方法", 《电子器件》 * |
| 牟晓光等: "智能型二线制温度变送器", 《哈尔滨商业大学学报（自然科学版）》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113176004A (en) * | 2021-04-26 | 2021-07-27 | 精进电动科技股份有限公司 | Temperature measurement circuit and motor controller |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108955933B (en) | 2021-06-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105547126A (en) | Eddy current displacement sensor | |
| CN110687347A (en) | Hall current sensor with temperature compensation and temperature compensation method thereof | |
| CN109541291B (en) | Wide-temperature high-precision multi-path current acquisition system | |
| US20140333290A1 (en) | Method for Improving Common Mode Rejection in a Rogowski Coil-Based Circuit | |
| CN110672902A (en) | Magnetic field gathering assembly, non-contact leakage current measuring device and measuring method | |
| CN205537488U (en) | Eddy current displacement sensor | |
| CN108955933A (en) | A kind of measuring circuit and parameter selection method improving rail temperature measurement accuracy | |
| CN104916083A (en) | Internet of things based intelligent combustible gas inspection detector and calibration method thereof | |
| CN114594305A (en) | Differential non-contact voltage sensor | |
| CN108732414B (en) | Current sensor and circuit breaker | |
| CN211206616U (en) | Hall current sensor with temperature compensation | |
| CN108195480A (en) | A kind of high-precision temperature detection circuit | |
| CN111707869A (en) | High-resistance measuring device capable of automatically adjusting wide measuring range | |
| CN201096843Y (en) | Detection device for measuring metal conductivity instrument based on backset phase | |
| CN206740279U (en) | A kind of pressure measurement circuitry | |
| CN102080994A (en) | Isolated measurement technology of strain bridge circuit | |
| CN113820029A (en) | PT100 temperature acquisition circuit for acquisition terminal | |
| CN114483635A (en) | Magnetic bearing system, compressor and air conditioner | |
| CN212179985U (en) | High-temperature electromagnetic flowmeter | |
| CN104569906B (en) | A kind of three-phase intelligent ammeter nonlinear load accurate measurement analysis design method | |
| CN103575200A (en) | High-accuracy intelligent displacement sensor | |
| CN203642941U (en) | Multipath sensing single-channel constant current measuring device | |
| CN203191103U (en) | Environment analog quantity acquisition module | |
| CN211236012U (en) | High-precision alternating-current measurement frequency response compensation circuit | |
| CN212134803U (en) | Wide-range high-precision voltage measuring device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |