CN111207849A - Temperature detection circuit and temperature detection method - Google Patents

Temperature detection circuit and temperature detection method Download PDF

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Publication number
CN111207849A
CN111207849A CN202010036899.8A CN202010036899A CN111207849A CN 111207849 A CN111207849 A CN 111207849A CN 202010036899 A CN202010036899 A CN 202010036899A CN 111207849 A CN111207849 A CN 111207849A
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temperature
thermocouple
hot
cold
thermoelectric
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冯雪
傅棋琪
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Tsinghua University
Institute of Flexible Electronics Technology of THU Zhejiang
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Tsinghua University
Institute of Flexible Electronics Technology of THU Zhejiang
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Priority to CN202010036899.8A priority Critical patent/CN111207849A/en
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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
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • 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
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • G01K7/10—Arrangements for compensating for auxiliary variables, e.g. length of lead
    • G01K7/12—Arrangements with respect to the cold junction, e.g. preventing influence of temperature of surrounding air
    • 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
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • G01K7/10—Arrangements for compensating for auxiliary variables, e.g. length of lead
    • G01K7/12—Arrangements with respect to the cold junction, e.g. preventing influence of temperature of surrounding air
    • G01K7/13—Circuits for cold-junction compensation

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  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

The invention discloses a temperature detection circuit and a temperature detection method, wherein the temperature detection circuit comprises: a thermocouple; the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal; the thermistor is used for sensing the temperature of the cold end of the thermocouple; and the controller is used for obtaining cold-end thermoelectric force according to the cold-end temperature of the thermocouple, obtaining hot-end thermoelectric force according to the digital hot-end thermoelectric force signal, calculating to obtain target thermoelectric force according to the hot-end thermoelectric force and the cold-end thermoelectric force, and obtaining the hot-end temperature of the thermocouple according to the target thermoelectric force. The circuit adopts an inverse temperature measurement algorithm, realizes hot end thermoelectric force correction according to hot end thermoelectric force and cold end thermoelectric force of the thermocouple, further obtains hot end temperature of the thermocouple, and has good flexibility, high precision and wide application range.

Description

Temperature detection circuit and temperature detection method
Technical Field
The invention relates to the technical field of temperature detection, in particular to a temperature detection circuit and a temperature detection method.
Background
Thermoelectric potentials corresponding to all temperatures in a thermoelectric potential chart of the thermocouple are calibrated based on cold end reference temperature of 0 ℃ (centigrade). However, in practical applications, in order to reduce the volume of the instrument and simplify the measurement device, the cold end temperature of the thermocouple is usually difficult to be guaranteed to be accurate 0 ℃, and the test result of the thermocouple is easily affected by factors such as the ambient temperature and the like, and a large error is generated, so that cold end compensation plays an important role in a thermocouple temperature measurement system.
At present, the common methods for cold end compensation of the thermocouple include a freezing point device method, a compensation wire method, a thermoelectric force correction method and the like. The freezing point device method needs a constant temperature device, is complex to operate and is not suitable for industrial measurement, and the compensation lead method and the thermoelectric force correction method are limited by the compensation precision of the compensation lead and the correction precision of the thermoelectric force. Since a thermoelectric force error that cannot be eliminated exists between the compensation lead wire and the thermocouple wire, it is difficult to apply the compensation lead wire method to a high-precision thermo-couple. From this, it is known that the thermoelectric potential correction method is the highest precision cold junction compensation technique for a high precision thermocouple.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, an object of the present invention is to provide a temperature detection circuit, which uses an inverse temperature measurement algorithm to correct the hot-end thermoelectric potential according to the hot-end thermoelectric potential and the cold-end thermoelectric potential of a thermocouple, so as to obtain the hot-end temperature of the thermocouple.
Another object of the present invention is to provide a temperature detecting method.
To achieve the above object, an embodiment of a first aspect of the present invention provides a temperature detection circuit, including: a thermocouple; the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal; the thermistor is used for sensing the cold end temperature of the thermocouple; and the controller is used for obtaining cold-end thermoelectric force according to the cold-end temperature of the thermocouple, obtaining hot-end thermoelectric force according to the digital hot-end thermoelectric force signal, calculating to obtain target thermoelectric force according to the hot-end thermoelectric force and the cold-end thermoelectric force, and obtaining the hot-end temperature of the thermocouple according to the target thermoelectric force.
According to the temperature detection circuit provided by the embodiment of the invention, the analog hot end thermoelectric potential signal output by the hot end of the thermocouple is converted into the digital hot end thermoelectric potential signal through the analog-to-digital converter, the cold end temperature of the thermocouple is sensed through the thermistor, the cold end thermoelectric potential is obtained through the controller according to the cold end temperature of the thermocouple, the hot end thermoelectric potential is obtained according to the digital hot end thermoelectric potential signal, and then the target thermoelectric potential is obtained through calculation according to the hot end thermoelectric potential and the cold end thermoelectric potential, so that the hot end temperature of the thermocouple is obtained according to the target thermoelectric potential. Therefore, the circuit adopts an inverse temperature measurement algorithm, hot end thermoelectric potential correction is realized according to the hot end thermoelectric potential and the cold end thermoelectric potential of the thermocouple, and the hot end temperature of the thermocouple is obtained.
In addition, the temperature detection circuit according to the above embodiment of the present invention may further have the following additional technical features:
according to an embodiment of the invention, the controller is specifically configured to: storing a unitary high-order equation obtained after fitting a temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5; calculating to obtain an approximate cold end thermoelectric potential interval by adopting a dichotomy method according to the cold end temperature and the unitary high-order equation; and solving the unitary high-order equation by adopting a Newton iteration method according to the cold end thermoelectric potential interval and the cold end temperature to obtain the cold end thermoelectric potential which accords with preset precision.
According to one embodiment of the invention, the absolute value of the precision error of the thermistor is less than 0.04 degrees celsius.
According to one embodiment of the invention, the cold end temperature of the thermocouple is less than 80 degrees celsius.
According to an embodiment of the present invention, the temperature detection circuit further includes: and the display equipment is used for displaying the hot end temperature of the thermocouple.
According to one embodiment of the invention, the number of display bits of the display device is greater than 6 bits.
In order to achieve the above object, a second aspect of the present invention provides a temperature detecting method, which is applied to a temperature detecting circuit, where the temperature detecting circuit includes: a thermocouple; the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal; the thermistor is used for sensing the cold end temperature of the thermocouple; the temperature detection method comprises the following steps:
obtaining cold end thermoelectric potential according to the cold end temperature of the thermocouple; obtaining a hot end thermoelectric potential according to the digital hot end thermoelectric potential signal; calculating to obtain target thermoelectric force according to the hot end thermoelectric force and the cold end thermoelectric force; and obtaining the hot end temperature of the thermocouple according to the target thermoelectric potential.
According to the temperature detection method provided by the embodiment of the invention, the temperature detection circuit provided by the embodiment of the first aspect of the invention is applicable, firstly, the cold-end thermoelectric potential is obtained according to the cold-end temperature of the thermocouple, the hot-end thermoelectric potential is obtained according to the digital hot-end thermoelectric potential signal, then, the target thermoelectric potential is obtained through calculation according to the hot-end thermoelectric potential and the cold-end thermoelectric potential, and finally, the hot-end temperature of the thermocouple is obtained according to the target thermoelectric potential. Therefore, the method adopts an inverse temperature measurement algorithm, realizes hot-end thermoelectric force correction according to the hot-end thermoelectric force and the cold-end thermoelectric force of the thermocouple, and obtains the hot-end temperature of the thermocouple, and has the advantages of good flexibility, high precision and wide application range.
In addition, the temperature detection method according to the above embodiment of the present invention may further have the following additional technical features:
according to one embodiment of the invention, the obtaining of the cold-end thermoelectric potential according to the cold-end temperature of the thermocouple comprises: storing a unitary high-order equation obtained after fitting a temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5; calculating to obtain an approximate cold end thermoelectric potential interval by adopting a dichotomy method according to the cold end temperature and the unitary high-order equation; and solving the unitary high-order equation by adopting a Newton iteration method according to the cold end thermoelectric potential interval and the cold end temperature to obtain the cold end thermoelectric potential which accords with preset precision.
According to one embodiment of the invention, the absolute value of the precision error of the thermistor is less than 0.04 degrees celsius.
According to one embodiment of the invention, the cold end temperature of the thermocouple is less than 80 degrees celsius.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a schematic structural diagram of a temperature detection circuit according to an embodiment of the present invention;
FIG. 2 is a graph of the accuracy of a thermistor versus test temperature in accordance with one embodiment of the present invention;
FIG. 3 is a schematic flow chart of cold end compensation for a thermocouple according to one embodiment of the present invention;
FIG. 4 is a flow chart of calculating cold side thermoelectric potentials according to one embodiment of the present invention;
FIG. 5 is a schematic diagram of a temperature detection circuit according to an embodiment of the present invention;
fig. 6 is a flowchart of a temperature detection method according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
A temperature detection circuit and a temperature detection method of an embodiment of the present invention are described below with reference to the drawings.
It should be noted that in industrial production, drilling and manufacturing and forming of special high-performance materials, a high-temperature environment of about 1000 ℃ is usually required, and under the temperature condition, the thermocouple is the only commercially applicable contact type thermoelectric temperature sensor, and the temperature measurement precision of the thermocouple is directly related to the accuracy of the production control process and the quality of products. In the temperature measurement process of the thermocouple, if the temperature measurement error of the cold end is large, the error can be directly superposed on the measurement of the hot end of the thermoelectric potential, and finally, a larger temperature measurement error is caused. Therefore, the accuracy of correcting and compensating the thermoelectric potential difference caused by the cold end temperature difference has a very important influence on the measurement accuracy of the medium temperature.
Therefore, the embodiment of the invention provides a temperature detection circuit and a temperature detection method for correcting and compensating the thermal potential difference, so as to solve the problems of low temperature measurement precision and poor flexibility in the related art.
Fig. 1 is a schematic structural diagram of a temperature detection circuit according to an embodiment of the present invention.
As shown in fig. 1, the circuit 100 includes: a thermocouple 10, an analog-to-digital converter 20, a thermistor 30, and a controller 40.
The analog-to-digital converter 20 is configured to convert an analog hot-end thermoelectric potential signal output by the hot end of the thermocouple 10 into a digital hot-end thermoelectric potential signal; the thermistor 30 is used for sensing the cold end temperature of the thermocouple 10; the controller 40 is configured to obtain a cold-end thermoelectric potential according to the cold-end temperature of the thermocouple 10, obtain a hot-end thermoelectric potential according to the digital hot-end thermoelectric potential signal, calculate a target thermoelectric potential according to the hot-end thermoelectric potential and the cold-end thermoelectric potential, and obtain the hot-end temperature of the thermocouple 10 according to the target thermoelectric potential.
In one example, as shown in FIG. 2, the absolute value of the accuracy error of the thermistor 30 may be less than 0.04 deg.C (degrees Celsius). Based on the precision range of the thermistor, the cold junction temperature of the thermocouple 10 needs to be less than 80 ℃.
Specifically, when the thermocouple 10 performs temperature detection, the analog-to-digital converter 20 converts an analog hot-side thermoelectric potential signal output by the hot side of the thermocouple 10 into a digital hot-side thermoelectric potential signal, and sends the digital hot-side thermoelectric potential signal to the controller 40, and the thermistor 30 senses the cold-side temperature T of the thermocouple 10CAnd the temperature T of the cold endCIs sent to controller 40 to cause controller 40 to respond to cold end temperature T of thermocouple 10CCalculating to obtain cold end thermoelectric potential E (T)C，T0) Wherein, T0The temperature is 0 ℃, and the hot end thermoelectric potential E (T) is calculated according to the digital hot end thermoelectric potential signal1，TC) Wherein, T1Refers to a thermocouple10, and further according to the hot side thermoelectric potential E (T)1，TC) And cold side thermoelectric potential E (T)C，T0) Calculating to obtain a target thermoelectric potential E (T)1，T0) Finally according to the target thermoelectric potential E (T)1，T0) The hot end temperature T of the thermocouple 10 is obtained1Thereby achieving cold end compensation for thermocouple 10.
Wherein, the thermistor 30 can be an ON-409-PP, ON-909-44004 type high-precision thermistor, and can be bonded near the cold end of the thermocouple so as to sense the temperature of the cold end; the controller 40 (main control chip) may be internally provided with a fast and efficient temperature measurement algorithm.
That is, as shown in fig. 3, the circuit 100 first senses the temperature T of the cold end of the thermocouple 10 through the thermistor 30 with high accuracy, high reliability and low temperature drift according to the principle of thermoelectric force correctionCAnd sends it to the controller 40, and the controller 40 compares the cold end temperature T with the inverse temperature measurement algorithm, which is fast and efficientCTo thermocouple 10 at the cold end temperature TCThermoelectric potential at bottom, i.e. cold-side thermoelectric potential E (T)C，T0) Then, the cold-end thermoelectric potential is compensated to the hot-end thermoelectric potential E (T)1，TC) To obtain a target thermoelectric voltage E (T) with higher accuracy1，T0) I.e. E (T)1，T0)＝E(T1，TC)+E(TC，T0) Finally, the controller 40 controls the thermoelectric power E (T) according to the target thermoelectric power1，T0) Analyzing and calculating to obtain the accurate temperature T of the hot end1Thereby completing the accurate detection of the temperature.
Compared with the traditional freezer method, the thermoelectric force correction principle adopted by the circuit 100 not only can realize accurate cold end compensation, but also does not need a constant temperature device, is simple to operate and is suitable for industrial temperature measurement; compared with a compensation wire method and a thermoelectric potential correction method, the method has the advantages that not only can accurate cold end compensation be realized, but also the compensation wire is not needed, the compensation precision of the compensation wire and the correction precision of the thermoelectric potential are not needed, and the operation is simple and easy to realize. Therefore, the thermoelectric force correction principle adopted by the circuit 100 can be used for accurately acquiring the cold end temperatures of various thermocouples, and the application range is wide.
Therefore, the circuit adopts an inverse temperature measurement algorithm, realizes hot end thermoelectric force correction according to the hot end thermoelectric force and the cold end thermoelectric force of the thermocouple, further obtains the hot end temperature of the thermocouple, and has the advantages of good flexibility, high precision and wide application range.
In one embodiment of the present invention, the controller 40 may be specifically configured to: storing a unitary high-order equation f (x) obtained after fitting the temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5; according to cold end temperature TCAnd a unitary high-order equation f (x), calculating by adopting a dichotomy to obtain an approximate cold end thermoelectric potential interval; according to cold-end thermoelectric potential interval and cold-end temperature TCSolving a unitary high-order equation by adopting a Newton iteration method to obtain cold end thermoelectric potential E (T) meeting preset precisionC，T0)。
Specifically, the inverse temperature measurement algorithm in the controller 40 may include a temperature-thermoelectric potential curve of the thermocouple 10, a conversion error of the inverse temperature measurement algorithm may be less than 0.01%, and the controller 40 obtains a cold-end thermoelectric potential E (T) according to the cold-end temperature of the thermocouple 10C，T0) Firstly, as shown in fig. 4, a unitary high-order equation f (x) can be obtained by fitting a temperature-thermoelectric potential curve with a polynomial, and the unitary high-order equation f (x) is stored, wherein the order of the unitary high-order equation is greater than 5, the curve of the unitary high-order equation can be a fitted curve, and then, the temperature T of the cold end is used for obtaining the temperature T of the cold endCAnd a unitary high-order equation, calculating by adopting a dichotomy to obtain an approximate cold end thermoelectric potential interval, and finally, calculating according to the cold end thermoelectric potential interval and the cold end temperature TCAnd solving a unitary high-order equation by adopting a Newton iteration method to obtain the cold-end thermoelectric potential En which accords with the preset precision, wherein if (En +1-En)/En is less than 0.01%, the cold-end thermoelectric potential En accords with the preset precision.
For example, the fitted curve f (x) is first stored in the controller 40, and the cold end temperature T to be sensed at the thermistor 30CAfter the controller 40 is provided, the controller 40 first solves the approximate cold-end thermoelectric potential interval [ a, b ] by bisection method according to the following steps]：
Step 1, firstly, randomly taking an intermediate value O1 in a thermoelectric potential range [ p, q ] of a temperature-thermoelectric potential curve, substituting a fitting equation (unary high-order equation) to obtain Y1, and judging the size relation between Y1 and the received cold end temperature, so that the approximate cold end thermoelectric potential interval is reduced to [ p, O1] or [ O1, q ].
And 2, finding an intermediate value O2 of [ p, O1] or [ O1, q ], substituting the intermediate value O2 into a fitting equation to obtain Y2, and judging the size relation between Y2 and p or q, so that the thermoelectric potential interval is further reduced.
And analogizing until an approximate thermoelectric potential interval [ a, b ] is obtained, wherein the interval width can be determined according to the computing capability of the whole microcomputer.
Finally, the controller 40 solves a quadratic equation of a single element by using a Newton iteration method according to the cold-end thermoelectric potential interval [ a, b ] to obtain the hot-end temperature which meets the preset precision. Specifically, f '(X) is derived from the fitting function f (X), a value X1 is arbitrarily selected in the approximate temperature interval [ a, b ], the function X2 ═ X1-f (X)/f' (X) is substituted to obtain X2, and X2, X3 and the like can be obtained sequentially by circulating for multiple times until the difference (namely error) between f (Xn) and the received temperature meets the preset precision, and (f (Xn +1) -f (Xn))/f (Xn) < 0.01%, namely Xn is output, so that the cold-end thermoelectric potential En meeting the preset precision can be obtained.
In one embodiment of the present invention, as shown in fig. 5, the temperature detection circuit 100 may further include a display device 50. The display device 50 is used to display the hot end temperature of the thermocouple 10. The number of display bits of the display device 50 may be greater than 6 bits, that is, the display device 50 may have a high-precision digital display.
Specifically, referring to fig. 3, when obtaining the hot end accurate temperature of the thermocouple according to the target thermoelectric potential, the controller 40 may send the hot end accurate temperature to the display device 50, so that the display device 50 displays the hot end accurate temperature of the thermocouple 10, thereby implementing the visual display of the hot end accurate temperature.
In summary, the temperature detection circuit of the embodiment of the invention adopts the inverse temperature measurement algorithm to obtain the hot end temperature of the thermocouple according to the hot end potential and the cold end potential of the thermocouple, has good flexibility and high precision, and can be used for accurately collecting the cold end temperatures of various thermocouples.
Based on the same inventive concept, an embodiment of the present invention provides a temperature detection method, which is applicable to the temperature detection circuit shown in fig. 1, where the temperature detection circuit includes: a thermocouple; the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal; and the thermistor is used for sensing the cold end temperature of the thermocouple.
FIG. 6 is a flowchart illustrating a temperature detection method according to an embodiment of the invention.
As shown in fig. 6, the method comprises the steps of:
and S801, obtaining cold end thermoelectric force according to the cold end temperature of the thermocouple.
Specifically, obtaining the cold end thermoelectric potential according to the cold end temperature of the thermocouple may include: storing a unitary high-order equation obtained after fitting a temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5; according to the cold end temperature and the unitary high-order equation, calculating by adopting a dichotomy method to obtain an approximate cold end thermoelectric potential interval; and solving a unitary high-order equation by adopting a Newton iteration method according to the cold end thermoelectric potential interval and the cold end temperature to obtain the cold end thermoelectric potential which accords with the preset precision.
And S802, obtaining the hot-end thermoelectric potential according to the digital hot-end thermoelectric potential signal.
And S803, calculating to obtain the target thermoelectric potential according to the hot-end thermoelectric potential and the cold-end thermoelectric potential.
And S804, obtaining the hot end temperature of the thermocouple according to the target thermoelectric potential.
In one example, referring to fig. 2, the absolute value of the accuracy error of the thermistor can be less than 0.04 ℃ (celsius). Based on the precision range of the thermistor, the cold junction temperature of the thermocouple needs to be less than 80 ℃.
Specifically, when the thermocouple detects the temperature, the analog-to-digital converter converts an analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal and sends the digital hot end thermoelectric potential signal to the controller, and the thermistor senses the cold end temperature T of the thermocoupleCAnd the temperature T of the cold endCIs sent to the controller to cause the controller 40 to respond to the cold end temperature T of the thermocoupleCCalculating to obtain cold end thermoelectric potential E (T)C，T0) Wherein, T0The temperature of the measured medium is calculated according to the digital hot end thermoelectric potential signal to obtain a hot end thermoelectric potential E (T)1，TC) Wherein, T1Is the hot end temperature of the thermocouple, and further according to the hot end thermoelectric potential E (T)1，TC) And cold side thermoelectric potential E (T)C，T0) Calculating to obtain a target thermoelectric potential E (T)1，T0) Finally according to the target thermoelectric potential E (T)1，T0) The hot end temperature T of the thermocouple 10 is obtained1Thereby realizing cold end compensation of the thermocouple.
It should be noted that, for other specific implementations of the temperature detection method according to the embodiment of the present invention, reference may be made to the specific implementations of the temperature detection circuit according to the above-mentioned embodiment of the present invention, and details are not described here again to avoid redundancy.
According to the temperature detection method provided by the embodiment of the invention, the hot end thermoelectric potential is corrected according to the hot end thermoelectric potential and the cold end thermoelectric potential of the thermocouple by adopting an inverse temperature measurement algorithm, so that the hot end temperature of the thermocouple is obtained, and the method has the advantages of good flexibility, high precision and wide application range.
It should be noted that the logic and/or steps represented in the flowcharts or otherwise described herein, such as an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A temperature sensing circuit, comprising:
a thermocouple;
the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal;
the thermistor is used for sensing the cold end temperature of the thermocouple;
and the controller is used for obtaining cold-end thermoelectric force according to the cold-end temperature of the thermocouple, obtaining hot-end thermoelectric force according to the digital hot-end thermoelectric force signal, calculating to obtain target thermoelectric force according to the hot-end thermoelectric force and the cold-end thermoelectric force, and obtaining the hot-end temperature of the thermocouple according to the target thermoelectric force.
2. The temperature detection circuit of claim 1, wherein the controller is specifically configured to:
storing a unitary high-order equation obtained after fitting a temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5;
calculating to obtain an approximate cold end thermoelectric potential interval by adopting a dichotomy method according to the cold end temperature and the unitary high-order equation;
and solving the unitary high-order equation by adopting a Newton iteration method according to the cold end thermoelectric potential interval and the cold end temperature to obtain the cold end thermoelectric potential which accords with preset precision.
3. The temperature sensing circuit of claim 1, wherein an absolute value of a precision error of the thermistor is less than 0.04 degrees celsius.
4. The temperature sensing circuit of claim 1, wherein the cold end temperature of the thermocouple is less than 80 degrees celsius.
5. The temperature sensing circuit of claim 1, further comprising:
and the display equipment is used for displaying the hot end temperature of the thermocouple.
6. The temperature detection circuit of claim 5, wherein the number of display bits of the display device is greater than 6 bits.
7. A temperature detection method, adapted for use in a temperature detection circuit, the temperature detection circuit comprising: a thermocouple; the analog-to-digital converter is used for converting the analog hot end thermoelectric potential signal output by the hot end of the thermocouple into a digital hot end thermoelectric potential signal; the thermistor is used for sensing the cold end temperature of the thermocouple; the temperature detection method comprises the following steps:
obtaining cold end thermoelectric potential according to the cold end temperature of the thermocouple;
obtaining a hot end thermoelectric potential according to the digital hot end thermoelectric potential signal;
calculating to obtain target thermoelectric force according to the hot end thermoelectric force and the cold end thermoelectric force;
and obtaining the hot end temperature of the thermocouple according to the target thermoelectric potential.
8. The method of claim 7, wherein said deriving a cold end thermoelectric potential from a cold end temperature of said thermocouple comprises:
storing a unitary high-order equation obtained after fitting a temperature-thermoelectric potential curve, wherein the order number of the unitary high-order equation is greater than 5;
calculating to obtain an approximate cold end thermoelectric potential interval by adopting a dichotomy method according to the cold end temperature and the unitary high-order equation;
and solving the unitary high-order equation by adopting a Newton iteration method according to the cold end thermoelectric potential interval and the cold end temperature to obtain the cold end thermoelectric potential which accords with preset precision.
9. The temperature detection method according to claim 7, wherein an absolute value of a precision error of the thermistor is less than 0.04 degrees celsius.
10. The method of claim 7, wherein the cold end temperature of the thermocouple is less than 80 degrees celsius.
CN202010036899.8A 2020-01-14 2020-01-14 Temperature detection circuit and temperature detection method Pending CN111207849A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112021676A (en) * 2020-09-27 2020-12-04 胥海洲 High-precision heating temperature control circuit and control method thereof
CN113267265A (en) * 2021-05-21 2021-08-17 中国联合重型燃气轮机技术有限公司 Gas turbine gas temperature measurement system, gas turbine, and temperature measurement method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112021676A (en) * 2020-09-27 2020-12-04 胥海洲 High-precision heating temperature control circuit and control method thereof
CN113267265A (en) * 2021-05-21 2021-08-17 中国联合重型燃气轮机技术有限公司 Gas turbine gas temperature measurement system, gas turbine, and temperature measurement method

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