CN113820029A - PT100 temperature acquisition circuit for acquisition terminal - Google Patents
PT100 temperature acquisition circuit for acquisition terminal Download PDFInfo
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- CN113820029A CN113820029A CN202110067658.4A CN202110067658A CN113820029A CN 113820029 A CN113820029 A CN 113820029A CN 202110067658 A CN202110067658 A CN 202110067658A CN 113820029 A CN113820029 A CN 113820029A
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- conversion module
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- 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
- G01K7/18—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 linear resistance, e.g. platinum resistance thermometer
- G01K7/20—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 linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
- G01K7/206—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 linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit in a potentiometer circuit
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- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The invention discloses a PT100 temperature acquisition circuit for an acquisition terminal, which comprises a PT100 temperature acquisition circuit and an AD conversion module, wherein a PT100 platinum thermistor sensor adopts a three-wire connection method, a bridge circuit is adopted to measure a sampling signal, differential amplification processing is carried out on the sampling signal through operation and amplification, a voltage value is converted into a TTL digital signal from an analog quantity through the AD conversion module, the voltage adopted by the PT100 temperature acquisition circuit and the voltage adopted by an AD conversion module interface are the same voltage source, the influence caused by fluctuation of the working voltage of a system in a certain range is eliminated, and meanwhile, the sampling sensitivity is improved, so that the PT100 temperature acquisition circuit is simple in structure, low in cost, high in precision and sufficiently sensitive to temperature change perception.
Description
Technical Field
The invention relates to the technical field of temperature measurement and acquisition, in particular to a PT100 temperature acquisition circuit for an acquisition terminal.
Background
The device is generally required to monitor the temperature in real time and accurately in the field of power utilization information acquisition. Therefore, a temperature sensor meeting the requirements is required to be equipped. The PT100 platinum thermistor sensor is widely used in the temperature measurement field, and since the PT100 platinum thermistor sensor is very sensitive to temperature changes and has a small resistance value change when corresponding to the temperature changes, it needs to be used in combination with a high-precision and high-sensitive measurement circuit.
However, in the prior art, most of the conventional temperature sampling circuits formed by PT100 platinum thermal resistance sensors are complex in structure, are not sensitive enough to temperature changes, cannot sense slight temperature changes, and the working voltage of the system is affected by the environment, power supply ripple, the manufacturing process of the chip itself and the like, and often fluctuates greatly, so that the working voltage of the system fluctuates within a certain range, and the error of the working voltage of the system can cause the inaccuracy of the calculated and measured PT100 resistance value, thereby causing the measured temperature to be inaccurate.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art and provides a PT100 temperature acquisition circuit for an acquisition terminal, wherein a PT100 platinum thermistor sensor adopts a three-wire connection method, a bridge circuit is adopted to measure a sampling signal, differential amplification processing is carried out on the sampling signal through operational amplifier, a voltage value is converted into a TTL digital signal from an analog quantity through an AD conversion module, the voltage adopted by the PT100 temperature acquisition circuit and the voltage adopted by an AD conversion module interface are the same voltage source, and the PT100 temperature acquisition circuit has the advantages of simple structure, low cost, high precision and enough sensitivity for temperature change sensing.
In order to realize the purpose, the invention adopts the following technical scheme:
the utility model provides a PT100 temperature acquisition circuit for gathering terminal, this circuit includes PT100 temperature sampling circuit, AD conversion module, wherein:
the PT100 temperature sampling circuit is used for converting the resistance value of the PT100 platinum thermal resistance sensor into a voltage value and amplifying the voltage value;
the AD conversion module is used for converting the acquired output analog quantity voltage value of the sampling circuit into a TTL level digital signal;
the connection relationship is as follows: PT100I +, PT 100I-and PT 100I-COM of the PT100 platinum thermistor sensor are respectively connected with I +, I-and COM of a PT100 temperature acquisition circuit, the PT100 temperature acquisition circuit is connected with an AD conversion module through a PAT1, the AD conversion module outputs TTL level digital signals, and the system working voltage VAD simultaneously provides a voltage source for the bridge sampling circuit and the AD conversion module.
The PT100 acquisition circuit comprises a PT100 platinum thermal resistance sensor, an operational amplifier NIA, TVS protective devices VP1 and VP2, a system working voltage VAD, an output signal voltage PAT1, capacitors C1 and C2, resistors R2, R3, R4, R5, R6, R7 and R8. The connection relationship is that PT100I +, PT100I-, PT100I _ COM of a PT100 platinum thermal resistance sensor are respectively connected with I +, I-, COM of an acquisition circuit, resistors R2, R6, R1 and a thermosensitive PT100 jointly form a bridge circuit, resistors R2 and R6 divide voltage VAD to generate constant voltage V1, a resistor PT100 divides voltage VAD with a resistor R1 to generate voltage V2, resistors V1 and V2 are respectively connected in series with resistors R3 and R4 and are connected with AIN + and AIN-of an operational amplifier, AIN + of the operational amplifier is connected with a system ground through the resistor R4, AIN-of the operational amplifier is connected with a pin 1 of the operational amplifier through the resistor R7, working voltage VAD is connected with a system ground through a capacitor C1 and then connected with a pin 3 of the operational amplifier, a pin 2 of the operational amplifier is connected with the system ground, an output pin 1 of the operational amplifier is connected with one end of the resistor R8, and the other end of the resistor R8 is connected with a reference ground through a capacitor C2 and then connected with a PAT 1.
The AD conversion module comprises an input voltage PAT1, an AD conversion chip and an output signal DCAD _ OUT. The connection relationship is that the input voltage PAT1 is connected with the input pin of the AD conversion chip, and the analog voltage value obtained by sampling is output to the digital signal DCAD _ OUT through the AD conversion module.
In particular, R3 ═ R5 and R4 ═ R7, then the resistors R3, R4, R5, R7 and the operational amplifier NIA constitute a basic differential amplifier circuit.
Setting the system working voltage VAD to convert into a digital signal AD0, wherein the differential amplification factor is m, the voltage difference m & ltDelta & gt sampled by the AD conversion module is converted into a digital signal m & ltDelta & gt VAD, the number of bits of the AD conversion module is n, and the full-scale digital signal VAD0 & ltDelta & gt 2 & lt/Delta & gt corresponding to the voltage source VADn,
Both sides were approximated for VAD to know: the value of the PT100 resistor to be tested is only related to the digital signal VAD0 corresponding to the voltage source, the digital signal delta VAD corresponding to the bridge voltage difference delta V and the differential amplification factor m, so that the error caused by the fluctuation of the system working voltage VAD is eliminated, and the cost is reducedAnd the detection precision is improved.
Preferably, the operational amplifier is a TP1562A chip.
Preferably, the AD conversion module is an N76E003 chip, the internal AD is 12 bits, and the minimum resolution is 0.00122V.
The invention has the following beneficial effects:
1. the resistance value of the precision resistor used by the invention can be determined according to the temperature point or range to be measured, the high-precision resistors R2 and R6 divide the voltage to generate a constant voltage V1, the PT100 resistor and the precision resistor R1 divide the voltage to generate a voltage V2 to jointly form a bridge type measurement sampling circuit, and the bridge voltage is differentially amplified through an operational amplifier TP1562A, so that the temperature acquisition circuit can measure finer temperature change and has more sensitive characteristic to the temperature change, the invention can have the characteristic of high sensitivity, and the common-mode interference (the common-mode rejection ratio of the circuit is improved) can be inhibited and the temperature drift can be reduced.
2. Compared with the prior art, the voltage adopted by the PT100 temperature acquisition circuit and the voltage adopted by the AD conversion module interface are the same voltage source, the value of the PT100 resistor to be detected is only related to the digital signal VAD0 corresponding to the voltage source, the digital signal delta VAD corresponding to the bridge voltage difference delta V and the differential amplification factor m, and the error caused by the fluctuation of the system working voltage VAD is eliminated, so that the production cost is reduced, and the detection precision is improved.
3. The circuit of the invention adopts few devices, only consists of a PT100 resistor, an N76E003 chip, a TP1562A chip, necessary protective devices and resistance capacitors, and has the characteristics of small volume and simple structure.
Drawings
Fig. 1 is a diagram of a PT100 resistance temperature sampling and AD conversion circuit of a PT100 temperature acquisition circuit for an acquisition terminal.
Detailed Description
The present invention will be further described with reference to the accompanying drawings, and the following description is only for clearly illustrating the technical solutions of the present invention, and the protection scope of the present invention is not limited thereby.
The PT100 resistance temperature sampling and AD conversion circuit diagram of the PT100 temperature acquisition circuit for acquiring the terminal is shown as 1. PT100 acquisition circuit PT100 platinum resistance sensor, operational amplifier NIA, TVS protective device VP1 and VP2, system operating voltage VAD, output signal voltage PAT1, electric capacity C1, C2, resistance R2, R3, R4, R5, R6, R7, R8, AD conversion chip, output signal DCAD _ OUT. The connection relations of the PT100 platinum thermal resistance sensor are that PT100I +, PT 100I-PT 100I _ COM are respectively connected with I +, I-COM of the acquisition circuit, resistors R2, R6, R1 and a thermosensitive PT100 jointly form a bridge circuit, resistors R2 and R6 divide voltage VAD to generate constant voltage V1, a resistor PT100 divides voltage VAD by a resistor R1 to generate voltage V2, V1 and V2 are respectively connected with resistors R3 and R4 and AIN + and AIN-of an operational amplifier in series, the AIN + of the operational amplifier is connected with a system ground through a resistor R4, the AIN-of the operational amplifier is connected with a pin 1 of the operational amplifier through a resistor R7, the working voltage VAD is connected with a pin 3 of the operational amplifier after being connected with the system ground through a capacitor C1, a pin 2 of the operational amplifier is connected with the system ground, an output pin 1 of the operational amplifier is connected with one end of a resistor R8, the other end of the resistor R8 is connected with a reference ground through a capacitor C2 to output a voltage PAT1, a voltage PAT1 is connected with an input pin of an AD conversion chip, and the sampled analog voltage value is output by an AD conversion module to DCOUT.
In particular, R3 ═ R5 and R4 ═ R7, then the resistors R3, R4, R5, R7 and the operational amplifier NIA constitute a basic differential amplifier circuit.
Setting the system working voltage VAD to convert into a digital signal AD0, wherein the differential amplification factor is m, the voltage difference m & ltDelta & gt sampled by the AD conversion module is converted into a digital signal m & ltDelta & gt VAD, the number of bits of the AD conversion module is n, and the full-scale digital signal VAD0 & ltDelta & gt 2 & lt/Delta & gt corresponding to the voltage source VADn,
Both sides were approximated for VAD to know: the value of the PT100 resistor to be detected is only related to the digital signal VAD0 corresponding to the voltage source, the digital signal delta VAD corresponding to the bridge voltage difference delta V and the differential amplification factor m, so that the error caused by the fluctuation of the system working voltage VAD is eliminated, the cost is reduced, and the detection precision is improved.
For example, the number of times that differential amplification is required may be changed by adjusting the values of the resistors R3, R4, R5, and R7, or the values of V1 and V2 may be adjusted by adjusting the values of the resistors R1, R2, and R6.
The resistance value of the precision resistor used by the invention can be determined according to the temperature point or range to be measured, the high-precision resistors R2 and R6 divide the voltage to generate a constant voltage V1, the PT100 resistor and the precision resistor R1 divide the voltage to generate a voltage V2 to jointly form a bridge type measurement sampling circuit, and the bridge voltage is differentially amplified through an operational amplifier TP1562A, so that the temperature acquisition circuit can measure finer temperature change and has more sensitive characteristic to the temperature change, the invention can have the characteristic of high sensitivity, and the common-mode interference (the common-mode rejection ratio of the circuit is improved) can be inhibited and the temperature drift can be reduced.
Compared with the prior art, the voltage adopted by the PT100 temperature acquisition circuit and the voltage adopted by the AD conversion module interface are the same voltage source, the value of the PT100 resistor to be detected is only related to the digital signal VAD0 corresponding to the voltage source, the digital signal delta VAD corresponding to the bridge voltage difference delta V and the differential amplification factor m, and the error caused by the fluctuation of the system working voltage VAD is eliminated, so that the production cost is reduced, and the detection precision is improved.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the invention, and are not intended to limit the scope of the invention, and all equivalent structures or equivalent processes that can be directly or indirectly implemented in the present specification and the attached drawings, or other related technical fields, are encompassed by the scope of the present invention.
Claims (5)
1. A PT100 temperature acquisition circuit for acquiring a terminal, comprising:
the PT100 temperature sampling circuit converts the resistance value of the PT100 platinum thermal resistance sensor into a voltage value and amplifies the voltage value;
the AD conversion module is used for converting the acquired output analog quantity voltage value of the PT100 temperature sampling circuit into a TTL level digital signal;
PT100I +, PT 100I-and PT100I _ COM of the PT100 platinum thermal resistance sensor are respectively connected with I +, I-and COM of a PT100 temperature acquisition circuit, the PT100 temperature acquisition circuit is connected with an AD conversion module through PAT1, the AD conversion module outputs TTL level digital signals, and system working voltage VAD simultaneously provides voltage sources for the bridge type sampling circuit and the AD conversion module.
2. The PT100 temperature acquisition circuit for the acquisition terminal as claimed in claim 1, wherein the PT100 platinum thermistor sensor, the operational amplifier NIA, the TVS protection devices VP1 and VP2, the system operating voltage VAD, the output signal voltage PAT1, the capacitors C1 and C2, the resistors R2, R3, R4, R5, R6, and R6 are connected with the I +, I, and COM of the acquisition circuit respectively, the resistors R6, and the thermistor 6 jointly form a bridge circuit, the resistors R6 and R6 generate a constant voltage V6, the resistor PT100 and the resistor R6 generate a voltage V6, the resistors V6 and V6 are connected with the operational amplifier AIN + and VAD of the operational amplifier, the operational amplifier VAD + operating voltage of the operational amplifier 6 is connected with the AIN + of the operational amplifier, the AIR 6 and VAD + operating voltage of the operational amplifier 6, the operational amplifier VAD + and AIN + operating voltage of the operational amplifier 6 are connected with the AIR 6, the operational amplifier 6, the AIR 6 and AIC 3, the operational amplifier 6 are connected with the operational amplifier system through the operational amplifier 6, the 2-pin of the operational amplifier is connected with the system ground, the output pin 1 of the operational amplifier is connected with one end of a resistor R8, and the other end of a resistor R8 is connected with the reference ground through a capacitor C2 to output a voltage PAT 1.
3. The PT100 temperature acquisition circuit for the acquisition terminal of claim 1, wherein the AD conversion module comprises an input voltage PAT1, an AD conversion chip, and an output signal DCAD _ OUT, wherein the input voltage PAT1 is connected to an input pin of the AD conversion chip, and the sampled analog voltage value outputs a digital signal DCAD _ OUT through the AD conversion module.
4. The PT100 temperature acquisition circuit for the acquisition terminal as claimed in claim 1, wherein R3-R5 and R4-R7, the resistors R3, R4, R5, R7 and the operational amplifier NIA form a basic differential amplification circuit.
5. The PT100 temperature acquisition circuit for an acquisition terminal as claimed in claim 1, wherein the system operating voltage VAD is set to be converted into a digital signal of AD0, the differential amplification factor is m, the voltage difference m × Δ V sampled by the AD conversion module is converted into a digital signal of m × Δ VAD, the number of bits of the AD conversion module is n, and the full-scale digital signal corresponding to the voltage source VAD is VAD0 ═ 2n,
Both sides were approximated for VAD to know: the value of the PT100 resistor to be detected is only related to the digital signal VAD0 corresponding to the voltage source, the digital signal delta VAD corresponding to the bridge voltage difference delta V and the differential amplification factor m, so that the error caused by the fluctuation of the system working voltage VAD is eliminated, the cost is reduced, and the detection precision is improved.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110067658.4A CN113820029A (en) | 2021-01-19 | 2021-01-19 | PT100 temperature acquisition circuit for acquisition terminal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110067658.4A CN113820029A (en) | 2021-01-19 | 2021-01-19 | PT100 temperature acquisition circuit for acquisition terminal |
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| CN113820029A true CN113820029A (en) | 2021-12-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202110067658.4A Withdrawn CN113820029A (en) | 2021-01-19 | 2021-01-19 | PT100 temperature acquisition circuit for acquisition terminal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114326504A (en) * | 2021-12-28 | 2022-04-12 | 深圳市和田古德自动化设备有限公司 | Intelligent control system of electronic product soldering tin equipment |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203587243U (en) * | 2013-11-25 | 2014-05-07 | 厦门龙净环保技术有限公司 | Temperature acquiring and processing circuit for electric-bag composite dust collector |
| CN103913249A (en) * | 2012-12-29 | 2014-07-09 | 北京谊安医疗系统股份有限公司 | Temperature monitoring circuit device and method |
| CN111735553A (en) * | 2020-07-23 | 2020-10-02 | 台州师同人信息技术有限公司 | PT100 temperature collector with Modbus485 communication |
| CN211626739U (en) * | 2019-09-10 | 2020-10-02 | 成都昆朋新能科技有限公司 | PT100 platinum thermal resistance temperature sampling circuit |
-
2021
- 2021-01-19 CN CN202110067658.4A patent/CN113820029A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103913249A (en) * | 2012-12-29 | 2014-07-09 | 北京谊安医疗系统股份有限公司 | Temperature monitoring circuit device and method |
| CN203587243U (en) * | 2013-11-25 | 2014-05-07 | 厦门龙净环保技术有限公司 | Temperature acquiring and processing circuit for electric-bag composite dust collector |
| CN211626739U (en) * | 2019-09-10 | 2020-10-02 | 成都昆朋新能科技有限公司 | PT100 platinum thermal resistance temperature sampling circuit |
| CN111735553A (en) * | 2020-07-23 | 2020-10-02 | 台州师同人信息技术有限公司 | PT100 temperature collector with Modbus485 communication |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114326504A (en) * | 2021-12-28 | 2022-04-12 | 深圳市和田古德自动化设备有限公司 | Intelligent control system of electronic product soldering tin equipment |
| CN114326504B (en) * | 2021-12-28 | 2024-03-26 | 深圳市和田古德自动化设备有限公司 | Intelligent control system of electronic product soldering tin equipment |
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Application publication date: 20211221 |
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