CN207280617U - High precision temperature acquisition device based on PT100 - Google Patents

Abstract

The utility model discloses a high-precision temperature collector based on PT100, which uses a low-temperature drift precision resistor as a reference resistor, and the sensor and the reference resistor are connected in series through the same constant current source, and their voltage signals are connected to the same amplifier and A/D circuit In addition, DS18B20 is also introduced to measure the ambient temperature of HMTS, and the value of the reference resistance changing with temperature is introduced into the memory, and the high-precision measurement of temperature is achieved by comparing the reference resistance and the sensor voltage value; the utility model uses low-temperature drift precision resistance as a reference Resistors, sensors and reference resistors are connected in series through the same constant current source, and their voltage signals are connected to the same amplifier and A/D circuit. In addition, DS18B20 is introduced to measure the ambient temperature of HMTS, and the value of the reference resistor changing with temperature is introduced into the memory. , by comparing the reference resistance and the sensor voltage value to achieve high-precision measurement of temperature.

Description

High precision temperature collector based on PT100

Technical field:

The utility model relates to the technical field of equipment measurement in the electric power industry, in particular to a PT100-based high-precision temperature collector.

Background technique:

PT100 temperature sensor is widely used in meteorology, agriculture, forestry, chemical fiber, food, automobile, household appliances, industrial automation measurement and various experimental instruments and meters due to its high precision, good stability, strong reliability and long life.

However, the existing sensors only measure the working temperature alone without considering the influence on the working environment temperature, and this process will affect the temperature detection accuracy.

Utility model content:

The technical problem to be solved by the utility model is: to overcome the deficiencies of the prior art, to provide a low-temperature drift precision resistor as a reference resistor, the sensor and the reference resistor are connected in series through the same constant current source, and the voltage signal is connected to the same amplifier and A/D circuit, in addition, DS18B20 is introduced to measure the ambient temperature of HMTS, and the value of the reference resistance changing with temperature is introduced into the memory, and the high-precision temperature acquisition based on PT100 is achieved by comparing the reference resistance and the sensor voltage value to achieve high-precision temperature measurement. device.

The technical scheme of the utility model is: a high-precision temperature collector based on PT100, including a single-chip microcomputer control module, a signal conditioning module, an A/D conversion module, a data storage module, a liquid crystal display module, a PT100 temperature sensor, DS18B20, a main acquisition The PT100 temperature sensor converts the temperature change into a corresponding voltage signal output, and after the signal conditioning circuit and the amplification circuit, the A/D conversion is performed by the A/D conversion module and stored in the data storage module. DS18B20 measures the ambient temperature of the main collector module, and introduces the value of the reference resistance changing with the temperature into the data storage module. After the single-chip control module processes the data in the data storage module, it sends it to the liquid crystal display module for display. The collector module realizes data interaction;

The signal conditioning module includes a TLC2652 chip, a TL431 chip and a PT100, the TL431 chip and the TLC2652 chip form a differential amplifier circuit, and one pin of the TLC2652 chip is connected in series with a resistor R11, a resistor R12 and a switch K1, and another tube of the TLC2652 chip The pin is connected in series with the resistor R0, resistor R13, resistor R14 and switch K2 and grounded through the resistor R2, the resistor R0 and the resistor R13 are connected to the switch K1 through a circuit, the resistor R11 and the resistor R12 and the resistor R13 and the resistor R14 is set to connect shunt with PT100.

The other pin of the TLC2652 chip is connected to the switch K2 through a shunt. Both the resistors R0 and R2 are high-precision resistors, and the resistor R0 is a reference resistor.

The beneficial effects of the utility model are:

1. The utility model uses a low-temperature drift precision resistor as a reference resistor. After the sensor and the reference resistor are connected in series, they pass through the same constant current source, and their voltage signals are connected to the same amplifier and A/D circuit. In addition, DS18B20 is introduced to measure the ambient temperature of the HMTS. , the value of the reference resistance changing with the temperature is introduced into the memory, and the high-precision measurement of the temperature can be achieved by comparing the reference resistance and the sensor voltage value.

2. The AT89C52 single-chip microcomputer of the utility model is the core, and the PT100 temperature sensor converts the temperature change into a corresponding voltage signal output, which is sent to the single-chip microcomputer after the conditioning circuit and A/D conversion, and the single-chip microcomputer sends the data to the digital tube module for display , and at the same time realize data interaction with the main HMTS through RS232.

Description of drawings:

Figure 1 is a block diagram of the electrical connection of a PT100-based high-precision temperature collector.

Figure 2 shows the signal conditioning circuit.

Figure 3 is a work flow chart.

Detailed ways:

Embodiment: see Fig. 1, Fig. 2 and Fig. 3.

PT100-based high-precision temperature collector, including single-chip control module, signal conditioning module, A/D conversion module, data storage module, liquid crystal display module, PT100 temperature sensor, DS18B20, main collector module and power supply module, PT100 temperature The sensor converts the temperature change into a corresponding voltage signal output, after passing through the signal conditioning circuit and the amplification circuit, the A/D conversion module performs A/D conversion and stores it in the data storage module. At the same time, the DS18B20 measures the ambient temperature of the main collector module. , introduce the value of the reference resistance changing with the temperature into the data storage module, the single-chip control module processes the data in the data storage module, and sends it to the liquid crystal display module for display, and realizes data interaction with the main collector module through RS232 at the same time;

The signal conditioning module includes TLC2652 chip, TL431 chip and PT100, TL431 chip and TLC2652 chip form a differential amplifier circuit, and one pin of TLC2652 chip is connected in series with resistor R11, resistor R12 and switch K1, the other pin of TLC2652 chip is connected with resistor R0 , resistor R13, resistor R14 and switch K2 are connected in series and grounded through resistor R2, the resistor R0 and resistor R13 are connected to the switch K1 through a circuit, and the resistor R11 and resistor R12 and the resistor R13 and resistor R14 are connected to PT100 branch.

The other pin of the TLC2652 chip is connected to the switch K2 through a shunt. Both resistors R0 and R2 are high-precision resistors, and resistor R0 is a reference resistor.

As shown in Figure 2. The measurement circuit is designed in a four-wire system, and a precise constant current source is required in this four-wire structure; in addition, because the output signal of the unit measurement circuit is weak, the output signal needs to be amplified by DC. Then perform A/D conversion.

The current value of the constant current source is set at 0.25mA, and the switches K1 and K2 are controlled by the single-chip microcomputer, and when both are in the position shown in the figure, the voltage reference source TL431 makes the input voltage of the V+ terminal of the TLC2652 2.5V. According to the characteristics of the ideal op amp, there is V+ =V-=2.5V, and there is no current flowing out of the V- terminal, then the current flowing through R2 is 0.25mA. If there is no current in R12 and R14, the PT100 current is equal to the R2 current, which is 0.25mA, that is, the constant current source flowing through PT100 is 0.25mA; R0 and R2 use high-precision resistors with the same temperature drift. When the switches K1 and K2 are both When it is in another position as shown in the figure, the current flowing through R0 is also a constant 0.25mA, which will be used for circuit temperature compensation and calibration.

The high-precision PT100 sensor is used for temperature measurement, and the temperature value has a one-to-one correspondence with the PT100 resistance value. As long as the accurate R _PT100 is obtained, the accurate t can be calculated. The key to temperature measurement is to measure the resistance value RPT100 of PT100. The corresponding formula of resistance and temperature is:

R _PT100 =R ₀ (1+At+Bt ² )

From this it follows that:

ΔR _PT100 =R ₀ (AΔt+2BΔt)

When in use: the PT100 temperature sensor converts the temperature change into a corresponding voltage signal output, after the signal conditioning circuit and the amplification circuit, the A/D conversion module performs A/D conversion and stores it in the data storage module, and at the same time, the DS18B20 measures the main collector The ambient temperature of the module works, and the value of the reference resistance changing with the temperature is introduced into the data storage module. After the single-chip control module processes the data in the data storage module, it is sent to the liquid crystal display module for display. At the same time, the data is realized through the RS232 and the main collector module. interact.

The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the utility model, All still belong to within the scope of the technical solution of the utility model.

Claims (3)

1. a kind of high precision temperature acquisition device based on PT100, including single chip control module, Signal-regulated kinase, A/D conversion Module, data memory module, LCD MODULE, PT100 temperature sensors, DS18B20, main collector module and the electricity of power supply Source module, it is characterized in that：The change of temperature is converted into corresponding voltage signal and exported by PT100 temperature sensors, by signal Data memory module is stored in after carrying out A/D conversions by A/D modular converters after modulate circuit and amplifying circuit, at the same time DS18B20 measures the environment temperature of main collector module work, and the value that reference resistance is varied with temperature introduces data storage mould Block, after single chip control module is to the data processing in data memory module, send to LCD MODULE and is shown, leads at the same time Cross RS232 and realize data interaction with main collector module；

The Signal-regulated kinase includes TLC2652 chips, TL431 chips and PT100, the TL431 chips and TLC2652 cores Piece forms differential amplifier circuit, and a pin of TLC2652 chips is connected with resistance R11, resistance R12 and switch K1, While another pin of TLC2652 chips is connected with resistance R0, resistance R13, resistance R14 and switch K2 and by resistance R2 Ground connection, is connected, the resistance R11 and resistance R12 and resistance between the resistance R0 and resistance R13 by circuit with switch K1 It is respectively provided between R13 and resistance R14 and is connected branch with PT100.

2. the high precision temperature acquisition device according to claim 1 based on PT100, it is characterized in that：The TLC2652 chips Another pin by branch with switch K2 be connected.

3. the high precision temperature acquisition device according to claim 1 based on PT100, it is characterized in that：The resistance R0 and R2 It is high-accuracy resistance, and the resistance R0 is reference resistance.