CN202075059U - Novel platinum resistor temperature measurement module - Google Patents
Novel platinum resistor temperature measurement module Download PDFInfo
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- CN202075059U CN202075059U CN2011201613230U CN201120161323U CN202075059U CN 202075059 U CN202075059 U CN 202075059U CN 2011201613230 U CN2011201613230 U CN 2011201613230U CN 201120161323 U CN201120161323 U CN 201120161323U CN 202075059 U CN202075059 U CN 202075059U
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Abstract
The utility model discloses a novel platinum resistor temperature measurement module, which is characterized in that: a platinum resistor input end is connected to a constant-voltage intermediate voltage division differential input circuit; differential amplification is performed through a multi-way switch and a differential amplifying circuit; a signal which is subjected to the differential amplification is input into a double-integral A/D (Analog/Digital) conversion module to perform analog-digital conversion; a digital signal which is subjected to the analog-digital conversion is transmitted to an STM (Scanning Tunneling Microscope) singlechip; an output end of the STM singlechip is connected to a communication output end through a photoelectric isolation module and an RS485 communication circuit; and a power supply is used for supplying power for the RS485 communication circuit through a voltage DC-DC (Direct Current-Direct Current) step-down and isolation module and is connected in series with the DC-DC isolation module through the voltage DC-DC step-down and isolation module to supply power for the STM singlechip. The module has the advantages that: Pt100 and Pt1000 sensors are used, and error of a wire and error of a platinum resistor connecting wire caused by ambient temperature are compensated by using ambient temperature detection, so that high-accuracy temperature measurement is realized, and the reliability and the stability of the module are guaranteed.
Description
Technical field:
The utility model relates to a kind of novel platinum resistance temperature-measuring module.
Background technology:
Platinum resistance temperature sensor is to utilize its resistance to become certain funtcional relationship with temperature and the temperature sensor made, because its accuracy of measurement height, measurement range are big, repdocutbility and good stability etc., are widely used in the temperature survey of middle temperature (200 ℃～650 ℃) scope.The instrument of using platinum resistance measurement temperature is a lot, and connection type is various, adopts two-wire system, three-wire system, four-wire system method of attachment usually, and characteristics are respectively arranged.Two-wire system: the sensor resistance changing value be connected the output valve that the conductor resistance value constitutes sensor jointly because the additive error brought of conductor resistance makes actual measured value higher, be used for the less demanding occasion of measuring accuracy, and the length of lead is unsuitable long; Three-wire system: three sectional area of wire that require to draw and identical length with, the circuit of measuring platinum resistance generally is a unbalanced bridge, platinum resistance is as an arm resistance of electric bridge, with power end of receiving electric bridge of lead, on all the other two brachium pontis of receiving the brachium pontis at platinum resistance place respectively and being adjacent, when bridge balancing, the variation of conductor resistance to measurement result without any influence, so just eliminated the measuring error that wire line resistance brings, but be necessary for congruent arm electric bridge, otherwise can not eliminate the influence of conductor resistance fully.Adopt three-wire system can reduce the additive error that conductor resistance brings greatly, the industrial three-wire system connection that generally all adopts; Four-wire system: when measuring resistance numerical value is very little, the resistance of p-wire may be introduced obvious errors, four lines are measured and are provided steady current with two additional testing lines, two voltage drops that p-wire is measured unknown resistance in addition, under the sufficiently high condition of voltage table input impedance, electric current flows through voltage table hardly, so just can accurately measure the pressure drop on the unknown resistance, calculates resistance value.In order to realize on-the-spot applying in a flexible way, various platinum resistor temperature measuring modules release one after another.
The platinum resistance module is used now very extensive, as at the refrigerator detection line, and the detection of the heat-insulating property of building materials, the building external doors and windows heat-insulating property detects and industrial processes temperature detection or the like.Its feature is that point for measuring temperature is many, and is easy for installation, reduces construction cost, adopts low-cost plain conductor, can link to each other with host computer at a distance, realizes field bus control system.
Hyperchannel (4-8), difference input and high-precision platinum resistor temperature measuring module cost are all very high in the market.This type of temperature measurement module is in order to reach high-precision requirement, in the selection of device, adopt the chip with constant current source, bridge circuit, high precision operating amplifier, high-precision A/D and the photoelectric isolating device at a high speed of integrated chip (as the device of AD company or other brands) more.These high-grade device cost summations are up to hundreds of unit.In addition, for guaranteeing precision, generally use three-wire system and four-wire system, this class temperature measurement module reduces the input way of platinum resistance on the one hand, increases the cost that connects lead on the other hand.Copper conductor with 50 meters distances is example (1mm
2), if adopt three-wire system and four-wire system cost to increase respectively about 100 (rice) *, 1 (every meter/unit) * 8 (road)=800 yuan and 100 (rice) *, 1 (every meter/unit) * 8 (road) *, 2 (bar)=1600 yuan.
Existing temperature-measuring module adopts the difference input basically, in the module housing of standard, if adopt two-wire system, accomplishes the input of 8 tunnel difference at most; If adopt three-wire system and four-wire system, corresponding module input way is 5 the road and 4 the tunnel.
Summary of the invention:
The purpose of this utility model just provides a kind of novel low cost, high-precision platinum resistance temperature-measuring module, purpose is exactly to reduce cost to greatest extent, increase the module way, adopt two-wire system, the platinum resistance of utilizing environment temperature to detect compensating wire and environment temperature to cause connects the error of lead, realize high precision measuring temperature, guarantee its reliability and stability.
A kind of novel platinum resistance temperature-measuring module, comprise: the platinum resistance input end is connected to constant voltage intermediate section pressure reduction and divides input circuit, carry out the difference amplification through multi-way switch and differential amplifier circuit again, signal input double integration A/D modular converter after the difference amplification is carried out analog to digital conversion, give the STM single-chip microcomputer with the digital data transmission after the analog to digital conversion again, the output terminal of STM single-chip microcomputer is connected to the communication output terminal by photoelectric isolation module and RS485 telecommunication circuit; Power supply is given the power supply of RS485 telecommunication circuit by voltage DC-DC step-down isolation module, and is the power supply of STM single-chip microcomputer by voltage DC-DC step-down isolation module series connection DC-DC isolation module.
Adopt the STM single-chip microcomputer to be because its anti-electromagnetic interference capability is extremely strong,, in addition, have independent acquisition pulse width function, be convenient to precision switching time of dual integration A/D is calculated, improve precision for numeral and simulation lay the first stone altogether; Two, band hardware multiplication division can carry out a large amount of computings, and be exceedingly fast fast.
Described constant voltage intermediate section pressure reduction divides input circuit to be: the two ends of platinum resistance Rt are connected to the positive input and the reverse input end of a differential amplifier respectively by the first lead r1 and the second lead r2, positive input also connects power supply by divider resistance R3, and reverse input end is by divider resistance R4 ground connection.Rt is a platinum resistance, and r1, r2 (r1=r2=r) are that wire line resistance, R3, R4 are divider resistance, precision at least 0.1%.Computing formula is arranged: V=(Rt+2r) Vref/ (Rt+2r+R
3+ R
4) as can be known: the error that adopts the two-wire system thermometric to cause is relevant with the resistance r that connects lead, and certain when material, resistance r is relevant with the temperature of conductor length and lead, so will compensate.Method is: calibrate with upper computer software before using module, 1,2 end short circuits of the lead of platinum resistance will be connected, perhaps under lab find material identical, equal length, prismatic lead short circuit, module is at first measured environment temperature T this moment during calibration, records the magnitude of voltage V that is caused by lead then, and the above-mentioned derivation of equation goes out:
By calculating, be easy to obtain the conductor resistance value under this temperature; Utilize lead to follow temperature relation formula: r=r again
20[1+ α (T-20)] (r
20Be the resistance value of 20 ℃ of lower wires, α is a temperature coefficient of resistivity in the formula, and metal material is basic identical) obtain r
20Obviously, can obtain the resistance of lead this moment as long as know later environment temperature this moment.
Described multi-way switch and differential amplifier are to be provided with like this: constant voltage intermediate section pressure reduction divides input circuit to be connected to first multi-way switch, and the output terminal of first multi-way switch connects differential amplifier circuit, and differential amplifier circuit connects second multi-way switch again.
The input end of described second multi-way switch also is connected with zero compensation circuit and temperature collection circuit, carries out zero compensation and temperature collection.
Described power supply is the wide direct supply of 6V-40V, is 5V through the step-down of superpotential DC-DC step-down isolation module, is converted to positive and negative 5V voltage through the DC-DC isolation module again.
Described platinum resistance input end is 8 tunnel platinum resistance differential input ends.8 tunnel platinum resistance differential input ends can be arranged on the diverse location of circuit board, are provided with according to the structure of circuit board.
The utlity model has following advantage:
1, the wire jumper of realizing Pt100 and Pt1000 is selected, and module is discerned automatically, guarantees precision like this.
2, constant voltage intermediate section pressure reduction divides input, increases antijamming capability.Resistance is reasonably combined, realizes very high precision; Realize 8 tunnel inputs on the module, two-wire system is saved lead.
3, realize that automatic environment temperature detects, real-Time Compensation changes because of variation of ambient temperature causes conductor resistance.Obtain by host computer application software and corresponding operating before conductor resistance need use, but single channel or 8 road operation simultaneously obtains.
4, ambient temperature measurement point is according to circumstances chosen, and module is provided with lead-in wire.
Description of drawings:
Fig. 1 is the electrical schematic diagram of the utility model embodiment;
Fig. 2 divides the circuit diagram of input circuit for constant voltage intermediate section pressure reduction.
Embodiment
Embodiment with indefiniteness further explains, illustrates the technical program below.
A kind of novel platinum resistance temperature-measuring module, as shown in Figure 1, comprise: 8 tunnel platinum resistance input ends are connected to constant voltage and divide middle pressure reduction to divide input circuit, carry out the difference amplification through multi-way switch and differential amplifier circuit again, signal input double integration A/D modular converter after the difference amplification is carried out analog to digital conversion, give the STM single-chip microcomputer with the digital data transmission after the analog to digital conversion again, the output terminal of STM single-chip microcomputer is connected to the communication output terminal by photoelectric isolation module and RS485 telecommunication circuit; Power supply is given the power supply of RS485 telecommunication circuit by voltage DC-DC step-down isolation module, and is the power supply of STM single-chip microcomputer by voltage DC-DC step-down isolation module series connection DC-DC isolation module.
Described multi-way switch and differential amplifier are to be provided with like this: constant voltage intermediate section pressure reduction divides input circuit to be connected to first multi-way switch, and the output terminal of first multi-way switch connects differential amplifier circuit, and differential amplifier circuit connects second multi-way switch again.The input end of second multi-way switch also is connected with zero compensation circuit and temperature collection circuit.The STM single-chip microcomputer also is connected with sensor and selects part and memory portion.
Constant voltage intermediate section pressure reduction divides input circuit as shown in Figure 2, the two ends of platinum resistance Rt are connected to the positive input and the reverse input end of a differential amplifier respectively by the first lead r1 and the second lead r2, positive input also connects power supply by divider resistance R3, reverse input end is by divider resistance R4 ground connection, precision at least 0.1%.Rt is a platinum resistance, and r1, r2 (r1=r2=r) they are that wire line resistance, R3, R4 are divider resistance, are generally about 10K, and 3,4 is the module terminals terminals, the 5, the 6th, and the input end of differential amplifier, the 7th, output terminal.Computing formula is arranged: V=(Rt+2r) Vref/ (Rt+2r+R
3+ R
4) as can be known: the error that adopts the two-wire system thermometric to cause is relevant with the resistance r that connects lead, and certain when material, resistance r is relevant with the temperature of conductor length and lead, so will compensate.
Method is: calibrate with upper computer software before using module, 1,2 end short circuits of the lead of platinum resistance will be connected, perhaps under lab find material identical, equal length, prismatic lead short circuit, module is at first measured environment temperature T this moment during calibration, record the magnitude of voltage V that causes by lead then, utilize above-mentioned fortran to be:
Be easy to obtain the conductor resistance value under this temperature; Utilize formula: r=r again
20[1+ α (T-20)] (r
20Be the resistance value of 20 ℃ of lower wires, α is a temperature coefficient of resistivity in the formula, and metal material is basic identical) obtain r
20Obviously, can obtain the resistance of lead this moment as long as know later environment temperature this moment.
Environment temperature is that platinum resistance connects the environment temperature that lead is positioned in principle, if the gentle measurement point of environment can be guided to this actual environment humidity province with temperature sensor by line not a humidity province during calibration.Analyze in theory:, can ignore even resistance and the ambient temperature value of utilizing this circuit to record have error also very little to the measuring accuracy influence; And the factor that causes error is whether can reflect the actual environment temperature by the environment temperature that sensor records.If module temperature-sensitive and environment temperature are in a humidity province, then this module record temperature hardly can be because of lead length, temperature level and the error that causes, this type of situation such as refrigerator detection line all are in same workshop.But run into complicated scene unavoidably yet, and connect lead and move towards complexity, the environment temperature that may detect does not conform to the lead actual temperature, and this situation is wanted choose reasonable environment temperature point for measuring temperature, chooses the temperature spot that the meaning represented is arranged, and reduces difference as far as possible.The more for a short time temperature error that causes of difference is more little, and difference does not cause error almost can ignore very much.We might as well illustrate: the error that the environment temperature that records by module and the medial temperature of actual wire present position produce is calculated for 5 ℃, is 100 meters with length, and cross-sectional area is 1mm
2Copper conductor be example (20 ℃ of following situations), its resistance is
r＝ρ
20l/s＝0.01724×100＝1.72Ω
100 meters conductor resistances, when temperature variation 5 ℃ the time, resistance variations
Δr＝r
t-r
20＝α(25-20)R
20＝0.004×5×1.72＝0.034Ω
Following formula α is a temperature coefficient of resistivity, and except that magnesium-yttrium-transition metal, the temperature coefficient of resistivity of most simple metal all is about 0.004/ degree centigrade.
The 2 Δ r that are changed to of whole line resistance are 0.0068 Ω, and the temperature variation that causes if adopt the Pt100 thermometric is 0.17 ℃; If 0.02 ℃ of the error that employing Pt1000 thermometric causes.In the actual use, complex situations are difficult to run into like this, and general so not long distance can not cause the temperature difference so big yet; Even so also can meet the demands.By the above: this module adopts benchmark to do constant voltage, dividing potential drop in the middle of adopting, difference is imported this method can effectively eliminate synchronous undesired signal, accomplishes accurate measurement.Add initialization of calibration, automatically compensate during thermometric, can make temperature survey follow lead length, variation of ambient temperature to have nothing to do, its measuring accuracy satisfy fully industrial three-wire system standard (the three-wire system wiring has two errors to exist: the one, lead causes error in the time of imbalance, the 2nd, variation of ambient temperature is error together), reach the requirement of four-wire system.
Claims (6)
1. novel platinum resistance temperature-measuring module, it is characterized in that comprising: the platinum resistance input end is connected to constant voltage intermediate section pressure reduction and divides input circuit, carry out the difference amplification through multi-way switch and differential amplifier circuit again, signal input double integration A/D modular converter after the difference amplification is carried out analog to digital conversion, give the STM single-chip microcomputer with the digital data transmission after the analog to digital conversion again, the output terminal of STM single-chip microcomputer is connected to the communication output terminal by photoelectric isolation module and RS485 telecommunication circuit; Power supply is given the power supply of RS485 telecommunication circuit by voltage DC-DC step-down isolation module, and is the power supply of STM single-chip microcomputer by voltage DC-DC step-down isolation module series connection DC-DC isolation module.
2. novel platinum resistance temperature-measuring module according to claim 1, it is characterized in that: described constant voltage intermediate section pressure reduction divides input circuit to be: the two ends of platinum resistance Rt are connected to the positive input and the reverse input end of a differential amplifier respectively by the first lead r1 and the second lead r2, positive input also connects power supply by divider resistance R3, and reverse input end is by divider resistance R4 ground connection.
3. novel platinum resistance temperature-measuring module according to claim 1 and 2, it is characterized in that: described multi-way switch and differential amplifier are to be provided with like this: constant voltage intermediate section pressure reduction divides input circuit to be connected to first multi-way switch, the output terminal of first multi-way switch connects differential amplifier circuit, and differential amplifier circuit connects second multi-way switch again.
4. novel platinum resistance temperature-measuring module according to claim 3 is characterized in that: the input end of described second multi-way switch also is connected with zero compensation circuit and temperature collection circuit.
5. novel platinum resistance temperature-measuring module according to claim 4 is characterized in that: described power supply is the wide direct supply of 6V-40V.
6. novel platinum resistance temperature-measuring module according to claim 5 is characterized in that: described platinum resistance input end is 8 tunnel platinum resistance differential input ends.
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| CN2011201613230U CN202075059U (en) | 2011-05-20 | 2011-05-20 | Novel platinum resistor temperature measurement module |
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| CN2011201613230U CN202075059U (en) | 2011-05-20 | 2011-05-20 | Novel platinum resistor temperature measurement module |
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| CN102901579A (en) * | 2012-09-27 | 2013-01-30 | 中国科学院长春光学精密机械与物理研究所 | High-reliability, low-power-consumption and light-weight temperature acquiring system of space camera |
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| CN104316209A (en) * | 2014-11-18 | 2015-01-28 | 吉林大学 | Aircraft engine inlet temperature measuring device and measuring method thereof |
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| CN112461397A (en) * | 2020-11-26 | 2021-03-09 | 云南电网有限责任公司电力科学研究院 | Electronic thermometer for detecting field temperature of oil-immersed transformer |
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- 2011-05-20 CN CN2011201613230U patent/CN202075059U/en not_active Expired - Fee Related
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| CN102901579A (en) * | 2012-09-27 | 2013-01-30 | 中国科学院长春光学精密机械与物理研究所 | High-reliability, low-power-consumption and light-weight temperature acquiring system of space camera |
| CN102901845B (en) * | 2012-10-24 | 2013-12-11 | 华东光电集成器件研究所 | Zero compensation testing device of piezoresistive acceleration sensor |
| CN102901845A (en) * | 2012-10-24 | 2013-01-30 | 华东光电集成器件研究所 | Zero compensation testing device of piezoresistive acceleration sensor |
| CN103675470B (en) * | 2013-11-11 | 2016-02-10 | 北京控制工程研究所 | A kind of N*M dimension resistor network measurement mechanism |
| CN103675470A (en) * | 2013-11-11 | 2014-03-26 | 北京控制工程研究所 | N*M dimension resistor network measuring device |
| CN104316209A (en) * | 2014-11-18 | 2015-01-28 | 吉林大学 | Aircraft engine inlet temperature measuring device and measuring method thereof |
| CN105203220B (en) * | 2015-10-29 | 2018-03-06 | 大庆市日上仪器制造有限公司 | A kind of saturated vapor pressure constant temperature warning device |
| CN105203220A (en) * | 2015-10-29 | 2015-12-30 | 大庆市日上仪器制造有限公司 | Saturated vapor pressure constant temperature alarm device |
| CN105651412A (en) * | 2016-02-03 | 2016-06-08 | 河南柴油机重工有限责任公司 | Measurement method and measurement circuit for PT1000 temperature sensor |
| CN105651412B (en) * | 2016-02-03 | 2018-09-11 | 河南柴油机重工有限责任公司 | A kind of measurement method and measuring circuit for PT1000 temperature sensors |
| CN112154310A (en) * | 2018-05-15 | 2020-12-29 | 微芯片技术股份有限公司 | Base resistance cancellation methods and related methods, systems, and apparatus |
| US11768115B2 (en) | 2018-05-15 | 2023-09-26 | Microchip Technology Incorporated | Base resistance cancellation method and related methods, systems, and devices |
| CN109632124A (en) * | 2019-02-13 | 2019-04-16 | 深圳市赛为智能股份有限公司 | It is tethered at unmanned aerial vehicle onboard monitoring system and its monitoring method |
| WO2020164286A1 (en) * | 2019-02-13 | 2020-08-20 | 深圳市赛为智能股份有限公司 | On-board monitoring system for tethered unmanned aerial vehicle, and monitoring method therefor |
| CN109632124B (en) * | 2019-02-13 | 2024-02-27 | 深圳市赛为智能股份有限公司 | Onboard monitoring system and method for tethered unmanned aerial vehicle |
| CN113494968A (en) * | 2020-03-19 | 2021-10-12 | 长鑫存储技术有限公司 | Temperature measurement and temperature calibration method and temperature measurement system |
| CN113494968B (en) * | 2020-03-19 | 2022-11-25 | 长鑫存储技术有限公司 | Temperature measurement and temperature calibration method and temperature measurement system |
| CN112461397A (en) * | 2020-11-26 | 2021-03-09 | 云南电网有限责任公司电力科学研究院 | Electronic thermometer for detecting field temperature of oil-immersed transformer |
| CN114636484A (en) * | 2022-05-09 | 2022-06-17 | 深圳市航顺芯片技术研发有限公司 | Digital temperature sensor, chip temperature detection system and chip temperature detection method |
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| C14 | Grant of patent or utility model | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20111214 Termination date: 20140520 |