CN111486983A - High-precision temperature measuring circuit with compensation function - Google Patents
High-precision temperature measuring circuit with compensation function Download PDFInfo
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- CN111486983A CN111486983A CN202010382542.5A CN202010382542A CN111486983A CN 111486983 A CN111486983 A CN 111486983A CN 202010382542 A CN202010382542 A CN 202010382542A CN 111486983 A CN111486983 A CN 111486983A
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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
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
- G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/20—Compensating for effects of temperature changes other than those to be measured, e.g. changes in ambient temperature
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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
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
- G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
- G01K7/25—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit for modifying the output characteristic, e.g. linearising
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
- Indication And Recording Devices For Special Purposes And Tariff Metering Devices (AREA)
Abstract
The invention discloses a high-precision temperature measuring circuit with a compensation function, which belongs to the technical field of power electronics, and comprises a thermistor signal processing circuit group for measurement, a thermistor signal processing circuit group for compensation and a temperature compensation circuit group, wherein the thermistor signal processing circuit group for measurement comprises a thermistor for measurement, a constant current circuit, a following circuit and a subtraction circuit; the compensation thermistor signal processing circuit group comprises a compensation thermistor, a constant current circuit, a following circuit and a subtraction circuit; the temperature measuring device can weaken the influence of the thermal resistance from a temperature measuring point to the thermistor body for measurement on processing errors, can obtain the temperature value of the temperature measuring point more accurately, can be adjusted according to practical application conditions by adopting the adjustable voltage division circuit, improves the application range, supplies power to the thermistor by using the constant current circuit, and is convenient for subsequent linear electric signal processing.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a high-precision temperature measuring circuit with a compensation function.
Background
A bridge arm of the MMC flexible direct-current transmission converter valve is formed by connecting a plurality of power units in series, each power module can generate power consumption of several kilowatts under a rated operation working condition, and the loss of the power modules can be influenced by the tube voltage drop, the opening state and the closing state of an IGBT in the power module, the forward voltage drop and the reverse recovery state of a diode. Because the water cooling flow of the power module is fixed, the temperature rise of the power device is measured, and the loss condition of the power module can be reflected.
At present, in a traditional temperature measurement method, a thermistor is mounted on a measured component and is connected to a temperature measurement plate through a lead for signal processing, but due to the existence of the lead, the temperature of a thermistor body is lower than that of a measured point, so that a temperature measurement error is caused, and the larger the temperature difference between the measured point and the temperature measurement plate is, the larger the measurement error is. In order to reduce the influence of thermistor leads on the temperature detection precision, a high-precision temperature measuring circuit with a compensation function is required.
Disclosure of Invention
1. Technical problem to be solved
Aiming at the problems in the prior art, the invention aims to provide a high-precision temperature measuring circuit with a compensation function, which can weaken the influence of thermal resistance from a temperature measuring point to a thermistor body for measurement on processing errors and can more accurately obtain the temperature value of the temperature measuring point.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
A high-precision temperature measuring circuit with a compensation function comprises a thermistor signal processing circuit group for measurement, a thermistor signal processing circuit group for compensation and a temperature compensation circuit group, wherein the thermistor signal processing circuit group for measurement comprises a thermistor for measurement, a constant current circuit, a following circuit and a subtraction circuit; the compensation thermistor signal processing circuit group comprises a compensation thermistor, a constant current circuit, a following circuit and a subtraction circuit; the temperature compensation circuit group comprises a subtraction circuit, an adjustable voltage division circuit, a following circuit and an addition circuit; the thermistor for measurement is arranged at a temperature measuring point, the thermistor for compensation is arranged on a temperature measuring plate, two ends of the thermistor for measurement are respectively connected to a constant current circuit of the thermistor signal processing circuit group for measurement, one end of the thermistor for measurement is connected with the non-inverting input end of a subtraction circuit in the thermistor signal processing circuit group for measurement, the other end of the thermistor for measurement is connected with the inverting input end of the subtraction circuit in the thermistor signal processing circuit group for measurement through a following circuit in the thermistor signal processing circuit group for measurement, and a temperature signal corresponding to the thermistor for measurement is obtained after the processing of the subtraction circuit;
the output end of the subtraction circuit in the thermistor signal processing circuit group for measurement is respectively connected with the non-inverting input end and the adding circuit of the subtraction circuit in the temperature compensation circuit group, the two ends of the thermistor for compensation are respectively connected with the constant current circuit of the thermistor signal processing circuit group for compensation, one end of the thermistor for compensation is connected with the non-inverting input end of the subtraction circuit in the thermistor signal processing circuit group for compensation, the other end of the thermistor for compensation is connected with the inverting input end of the subtraction circuit in the thermistor signal processing circuit group for compensation through the following circuit in the thermistor signal processing circuit group for compensation, and a temperature signal corresponding to the thermistor for compensation is obtained after the processing of the subtraction circuit;
the output end of the subtraction circuit in the thermistor signal processing circuit group for compensation is connected with the inverting input end of the subtraction circuit in the temperature compensation circuit group, the output end of the subtraction circuit in the temperature compensation circuit group is divided by the adjustable voltage division circuit and then is subjected to power amplification by the following circuit, namely, the temperature measuring point and the temperature difference value of the thermistor body for measurement, the output end of the subtraction circuit in the thermistor signal processing circuit group for measurement and the output end of the following circuit in the temperature compensation circuit group are both connected with the non-inverting input end of the adding circuit in the temperature compensation circuit group, the adding circuit in the temperature compensation circuit group sums the temperature of the thermistor body for measurement with the temperature measuring point and the temperature difference value of the thermistor body for measurement, the output signal of the adding circuit weakens the temperature value of the temperature measuring point, and the influence of the thermal resistance from the temperature measuring point to the thermistor body for measurement on processing errors can be realized, the temperature value of the temperature measuring point can be obtained more accurately, meanwhile, the adjustable voltage division circuit is adopted, adjustment can be carried out according to practical application working conditions, the application range is widened, and the constant current circuit is used for supplying power to the thermistor, so that subsequent linear electric signal processing is facilitated.
Further, the constant current circuit comprises a constant current operational amplifier, a non-inverting input end of the constant current operational amplifier is connected with a non-inverting end matching resistor, one end, far away from the constant current operational amplifier, of the non-inverting end matching resistor is connected with a filter capacitor, the filter capacitor is connected with a voltage stabilizing chip in parallel, the filter capacitor carries out filtering processing on the voltage stabilizing chip, a current limiting resistor is connected to a feedback end of the voltage stabilizing chip, one end, far away from the voltage stabilizing chip, of the current limiting resistor is connected with a power supply, a constant current sampling resistor is connected between the non-inverting input end of the constant current operational amplifier and the ground potential, and an electricity utilization element is.
Furthermore, the model of the voltage stabilizing chip is T L431, so that the voltage stabilizing chip has excellent performance and the price of the voltage stabilizing chip is reduced.
Furthermore, the following circuit comprises a following operational amplifier, the non-inverting input end of the following operational amplifier is connected with the signal end of the previous circuit, the inverting input end of the following operational amplifier is connected with the output end of the following operational amplifier, and the output end of the following operational amplifier is connected with the input end of the next circuit, so that the voltage signal of the previous circuit can be conveniently amplified.
Furthermore, the subtraction circuit comprises a subtraction operational amplifier, the in-phase input end of the subtraction operational amplifier is connected with an in-phase upper voltage-dividing resistor, an in-phase lower voltage-dividing resistor is further connected between the in-phase upper voltage-dividing resistor and the in-phase input end of the subtraction operational amplifier, the in-phase lower voltage-dividing resistor is grounded, the in-phase upper voltage-dividing resistor is connected with the output end of the previous circuit, the inverting input end of the subtraction operational amplifier is connected with an inverting input resistor, the inverting input resistor is connected with the output end of the previous circuit, the output end of the subtraction operational amplifier is connected with a feedback resistor, and one end, far away from the output end of the subtraction operational amplifier, of the feedback resistor is connected with the inverting input end.
Furthermore, adjustable bleeder circuit includes partial pressure adjustable resistor, the one end of going up partial pressure adjustable resistor is connected with the output of subtraction circuit in the temperature compensation circuit group, the one end that the subtraction circuit in the temperature compensation circuit group was kept away from to last partial pressure adjustable resistor is connected with the input of following circuit in the temperature compensation circuit group, be connected with bleeder resistor down between the following circuit in last partial pressure adjustable resistor and the temperature compensation circuit group, the one end ground connection of partial pressure adjustable resistor was kept away from to lower bleeder resistor, adjust the resistance of partial pressure adjustable resistor and lower bleeder resistor according to the actual application operating mode, improve temperature measurement circuit's application scope.
Furthermore, the addition circuit comprises an addition operational amplifier, wherein a first in-phase resistor and a second in-phase resistor are connected to the in-phase input end of the addition operational amplifier, the first in-phase resistor is connected with the output end of the subtraction circuit in the thermistor signal processing circuit group for measurement, the second in-phase resistor is connected with the output end of the following circuit in the temperature compensation circuit group, the reverse phase input end of the addition operational amplifier is connected with an addition reverse phase lower divider resistor, one end, far away from the addition operational amplifier, of the addition reverse phase lower divider resistor is grounded, and an addition feedback resistor is connected between the output end and the reverse phase input end of the addition operational amplifier, so that the processing precision of the voltage signal input into the addition operational amplifier is.
Furthermore, the constant-current operational amplifier, the following operational amplifier, the subtraction operational amplifier and the addition operational amplifier are all powered by the same power supply, so that the circuit structure is simplified, and the occupied space of the temperature measuring circuit equipment is saved.
Furthermore, the same resistance values of the in-phase upper voltage-dividing resistor, the in-phase lower voltage-dividing resistor, the reverse-phase input resistor and the feedback resistor are ensured, and the installation cost of the subtraction circuit is reduced while the processing precision of the subtraction circuit is ensured.
Furthermore, the first in-phase resistor, the second in-phase resistor, the voltage dividing resistor under the addition reverse phase and the addition feedback resistor have the same resistance value, so that the processing precision of the addition circuit is ensured, and the installation cost of the addition circuit is favorably reduced.
3. Advantageous effects
Compared with the prior art, the invention has the advantages that:
(1) the scheme can weaken the influence of the thermal resistance from the temperature measuring point to the thermistor body for measurement on processing errors, can obtain the temperature value of the temperature measuring point more accurately, adopts the adjustable voltage division circuit, can be adjusted according to practical application working conditions, improves the application range, applies the constant current circuit to supply power to the thermistor, and facilitates subsequent linear electric signal processing.
(2) The constant current circuit comprises a constant current operational amplifier, wherein a non-inverting input end of the constant current operational amplifier is connected with a non-inverting end matching resistor, one end, far away from the constant current operational amplifier, of the non-inverting end matching resistor is connected with a filter capacitor, the filter capacitor is connected with a voltage stabilizing chip in parallel, the filter capacitor carries out filtering processing on the voltage stabilizing chip, a feedback end of the voltage stabilizing chip is connected with a current limiting resistor, one end, far away from the voltage stabilizing chip, of the current limiting resistor is connected with a power supply, a constant current sampling resistor is connected between an inverting input end of the constant current operational amplifier and the ground potential, and an electricity utilization element.
(3) The model of the voltage stabilizing chip is T L431, and the voltage stabilizing chip has excellent performance and reduces the price.
(4) The following circuit comprises a following operational amplifier, the non-inverting input end of the following operational amplifier is connected with the signal end of the previous circuit, the inverting input end of the following operational amplifier is connected with the output end of the following operational amplifier, and the output end of the following operational amplifier is connected with the input end of the next circuit, so that the voltage signal of the previous circuit can be conveniently amplified.
(5) The subtraction circuit comprises a subtraction operational amplifier, wherein the in-phase input end of the subtraction operational amplifier is connected with an in-phase upper voltage-dividing resistor, an in-phase lower voltage-dividing resistor is further connected between the in-phase upper voltage-dividing resistor and the in-phase input end of the subtraction operational amplifier, the in-phase lower voltage-dividing resistor is grounded, the in-phase upper voltage-dividing resistor is connected with the output end of the previous circuit, the inverting input end of the subtraction operational amplifier is connected with an inverting input resistor, the inverting input resistor is connected with the output end of the previous circuit, the output end of the subtraction operational amplifier is connected with a feedback resistor, and one end, far away from the output end of the subtraction operational amplifier, of the feedback resistor is connected with the.
(6) Adjustable bleeder circuit includes partial pressure adjustable resistor, the one end of going up partial pressure adjustable resistor is connected with the output of subtraction circuit in the temperature compensation circuit group, the one end that the subtraction circuit in the temperature compensation circuit group was kept away from to go up partial pressure adjustable resistor is connected with the input of following circuit in the temperature compensation circuit group, be connected with bleeder resistor down between the following circuit in last partial pressure adjustable resistor and the temperature compensation circuit group, the one end ground connection of partial pressure adjustable resistor was kept away from to lower bleeder resistor, adjust the resistance of going up partial pressure adjustable resistor and bleeder resistor down according to the practical application operating mode, improve temperature measurement circuit's application scope.
(7) The summing circuit comprises a summing operational amplifier, wherein a non-inverting input end of the summing operational amplifier is connected with a first non-inverting resistor and a second non-inverting resistor, the first non-inverting resistor is connected with an output end of a subtraction circuit in a thermistor signal processing circuit group for measurement, the second non-inverting resistor is connected with an output end of a following circuit in a temperature compensation circuit group, an inverting input end of the summing operational amplifier is connected with a summing inverting lower divider resistor, one end, far away from the summing operational amplifier, of the summing inverting lower divider resistor is grounded, and a summing feedback resistor is connected between the output end and the inverting input end of the summing operational amplifier, so that the processing precision of voltage signals input into the summing operational amplifier is improved.
(8) The constant-current operational amplifier, the following operational amplifier, the subtraction operational amplifier and the addition operational amplifier are all powered by the same power supply, so that the circuit structure is simplified, and the occupied space of the temperature measuring circuit equipment is saved.
(9) The same resistances of the in-phase upper voltage-dividing resistor, the in-phase lower voltage-dividing resistor, the reverse-phase input resistor and the feedback resistor ensure the processing precision of the subtraction circuit and are beneficial to reducing the installation cost of the subtraction circuit.
(10) The first in-phase resistor, the second in-phase resistor, the addition inverting lower divider resistor and the addition feedback resistor have the same resistance value, so that the processing precision of the addition circuit is ensured, and the installation cost of the addition circuit is reduced.
Drawings
FIG. 1 is a schematic block diagram of the present invention;
FIG. 2 is a detailed functional block diagram of the present invention;
FIG. 3 is an overall circuit schematic of the present invention;
FIG. 4 is a schematic circuit diagram of a constant current circuit according to the present invention;
FIG. 5 is a circuit schematic of the follower circuit of the present invention;
FIG. 6 is a schematic circuit diagram of a subtraction circuit according to the present invention;
FIG. 7 is a schematic circuit diagram of an adjustable voltage divider circuit according to the present invention;
fig. 8 is a circuit schematic of the adder circuit of the present invention.
The reference numbers in the figures illustrate:
1 thermistor for measurement, 2 current-limiting resistor, 3 voltage-stabilizing chip, 4 filter capacitor, 5 in-phase end matching resistor, 6 constant current operational amplifier, 7 constant current sampling resistor, 8 following operational amplifier, 9 in-phase upper voltage-dividing resistor, 10 in-phase lower voltage-dividing resistor, 11 reverse phase input resistor, 12 subtraction operational amplifier, 13 feedback resistor, 14 thermistor for compensation, 15 upper voltage-dividing adjustable resistor, 16 lower voltage-dividing resistor, 17 first in-phase resistor, 18 second in-phase resistor, 19 addition reverse phase lower voltage-dividing resistor, 20 addition feedback resistor and 21 addition operational amplifier.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1:
referring to fig. 1-6, a high-precision temperature measurement circuit with compensation function includes a thermistor signal processing circuit group for measurement, a thermistor signal processing circuit group for compensation and a temperature compensation circuit group, wherein the thermistor signal processing circuit group for measurement includes a current limiting resistor 2, one end of the current limiting resistor 2 is connected with a power supply, one end of the current limiting resistor 2 away from the power supply is connected with a voltage stabilizing chip 3, the model of the voltage stabilizing chip 3 is T L431, the feedback end of the voltage stabilizing chip 3 is connected with the current limiting resistor 2, the voltage stabilizing chip 3 is connected in parallel with a filter capacitor 4, the filter capacitor 4 performs filtering processing on the voltage stabilizing chip 3, one end of the filter capacitor 4 is connected with a non-inverting end matching resistor 5, one end of the non-inverting end matching resistor 5 away from the filter capacitor 4 is connected with a constant current operational amplifier 6, the constant current operational amplifier 6 is grounded, the non-inverting input end of the constant current operational amplifier 6 is connected with the non-inverting end matching resistor 5, the inverting input end of the constant current operational amplifier 6 is connected with a thermistor 1, a sampling resistor 7 and a temperature measurement output end of the constant current operational amplifier 6, and the non-inverting end of the constant current operational amplifier 1 is connected with the constant current measuring output end of the thermistor 1;
the end of the constant current sampling resistor 7 far away from the constant current operational amplifier 6 is grounded, the non-inverting input end of the following operational amplifier 8 is connected with the inverting input end of the constant current operational amplifier 6, the inverting input end of the following operational amplifier 8 is connected with the output end of the following operational amplifier 8, the output end of the constant current operational amplifier 6 is also connected with a non-inverting upper divider resistor 9, the end of the non-inverting upper divider resistor 9 far away from the constant current operational amplifier 6 is respectively connected with a non-inverting lower divider resistor 10 and a subtraction operational amplifier 12, wherein the end of the non-inverting lower divider resistor 10 far away from the non-inverting upper divider resistor 9 is grounded, the non-inverting input end of the subtraction operational amplifier 12 is connected with the non-inverting upper divider resistor 9, a non-inverting input resistor 11 is connected between the inverting input end of the subtraction operational amplifier 12 and the output end of, the in-phase upper voltage-dividing resistor 9, the in-phase lower voltage-dividing resistor 10, the inverting input resistor 11 and the feedback resistor 13 have the same resistance value, and the output end of the subtraction operational amplifier 12 is the output end of the thermistor signal processing circuit group for measurement.
Referring to fig. 1-6, the compensation thermistor signal processing circuit group includes a current-limiting resistor 2, one end of the current-limiting resistor 2 is connected to a power supply, one end of the current-limiting resistor 2 away from the power supply is connected to a voltage-stabilizing chip 3, the voltage-stabilizing chip 3 is T L431, the feedback end of the voltage-stabilizing chip 3 is connected to the current-limiting resistor 2, the voltage-stabilizing chip 3 is connected in parallel to a filter capacitor 4, the voltage-stabilizing chip 3 is filtered by the filter capacitor 4, one end of the filter capacitor 4 is connected to a non-inverting terminal matching resistor 5, one end of the non-inverting terminal matching resistor 5 away from the filter capacitor 4 is connected to a constant-current operational amplifier 6, the constant-current operational amplifier 6 is grounded, the non-inverting terminal of the constant-current operational amplifier 6 is connected to the non-inverting terminal matching resistor 5, the inverting terminal of the constant-current operational amplifier 6 is connected to a compensation thermistor 14, a constant-current sampling resistor 7 and a follower operational amplifier 8, wherein the compensation thermistor 14 is further connected to an output terminal of the constant-current operational amplifier 6, i.e., two ends of the;
the end of the constant current sampling resistor 7 far away from the constant current operational amplifier 6 is grounded, the non-inverting input end of the following operational amplifier 8 is connected with the inverting input end of the constant current operational amplifier 6, the inverting input end of the following operational amplifier 8 is connected with the output end of the following operational amplifier 8, the output end of the constant current operational amplifier 6 is also connected with a non-inverting upper divider resistor 9, the end of the non-inverting upper divider resistor 9 far away from the constant current operational amplifier 6 is respectively connected with a non-inverting lower divider resistor 10 and a subtraction operational amplifier 12, wherein the end of the non-inverting lower divider resistor 10 far away from the non-inverting upper divider resistor 9 is grounded, the non-inverting input end of the subtraction operational amplifier 12 is connected with the non-inverting upper divider resistor 9, a non-inverting input resistor 11 is connected between the inverting input end of the subtraction operational amplifier 12 and the output end of, the in-phase upper voltage-dividing resistor 9, the in-phase lower voltage-dividing resistor 10, the inverting input resistor 11 and the feedback resistor 13 have the same resistance value, and the output end of the subtraction operational amplifier 12 is the output end of the compensation thermistor signal processing circuit group.
Referring to fig. 1-8, the temperature compensation circuit set includes an in-phase upper voltage-dividing resistor 9 and an inverse phase input resistor 11, wherein two ends of the in-phase upper voltage-dividing resistor 9 are respectively connected to an output end of the thermistor signal processing circuit set for measurement and an in-phase input end of the subtraction operational amplifier 12, an in-phase lower voltage-dividing resistor 10 is connected between the in-phase upper voltage-dividing resistor 9 and a ground point, two ends of the inverse phase input resistor 11 are respectively connected to an output end of the thermistor signal processing circuit set for compensation and an inverse phase input end of the subtraction operational amplifier 12, a feedback resistor 13 is connected between the inverse phase input end and the output end of the subtraction operational amplifier 12, an upper voltage-dividing adjustable resistor 15 is further connected to the output end of the subtraction operational amplifier 12, one end of the upper voltage-dividing adjustable resistor 15 far away from the subtraction operational amplifier, one end of the lower divider resistor 16, which is far away from the upper divider adjustable resistor 15, is grounded, and the in-phase input end of the following operational amplifier 8 is connected with the upper divider adjustable resistor 15, wherein the resistance value of the upper divider adjustable resistor 15 corresponds to the thermal resistance from the thermistor 1 body for measurement to the temperature measuring plate and the thermal resistance difference from the temperature measuring point to the thermistor 1 body for measurement, and the resistance value of the lower divider resistor 16 corresponds to the thermal resistance from the temperature measuring point to the thermistor 1 body for measurement;
the inverting input end of the following operational amplifier 8 is connected with the output end of the following operational amplifier 8, the output end of the following operational amplifier 8 is also connected with a second in-phase resistor 18, one end of the second in-phase resistor 18 far away from the following operational amplifier 8 is connected with the in-phase input end of an adding operational amplifier 21, the in-phase input end of the adding operational amplifier 21 is also connected with a first in-phase resistor 17, the first in-phase resistor 17 is connected with the output end of the thermistor signal processing circuit group for measurement, the inverting input end of the adding operational amplifier 21 is connected with an adding inverting lower divider resistor 19, one end of the adding inverting lower divider resistor 19 far away from the adding operational amplifier 21 is grounded, an adding feedback resistor 20 is connected between the output end and the inverting input end of the adding operational amplifier 21, and the first in-phase resistor 17, the second in-phase resistor 18, the adding inverting lower, the output end of the addition operational amplifier 21 is the signal output end of the temperature compensation circuit group and is also the signal output end of the circuit assembly.
When in use, a reference voltage source is composed of a current limiting resistor 2, a voltage stabilizing chip 3 and a filter capacitor 4, a reference voltage signal is provided for the non-inverting input end of a constant current operational amplifier 6 through a non-inverting matching resistor 5, a constant current circuit is composed of a constant current sampling resistor 7 and a constant current sampling resistor 7, a constant current power supply is provided for a thermistor 1 for measurement or a thermistor 14 for compensation, a signal amplification end voltage signal of the constant current power supply provided by the thermistor 1 for measurement or the thermistor 14 for compensation is amplified by a following operational amplifier 8, then is input into a subtraction circuit together with a signal non-amplification end voltage signal of the thermistor 1 for measurement or the thermistor 14 for compensation, a temperature signal corresponding to the thermistor 1 for measurement or the thermistor 14 for compensation can be obtained after being processed by the subtraction circuit, the output end of the thermistor signal processing circuit group for measurement and the output end of the thermistor signal processing circuit group for compensation are respectively connected to the subtraction circuit in the, the output end of the subtraction circuit is divided by an upper divider adjustable resistor 15 and a lower divider resistor 16, and then the signals amplified by the power of the follower circuit, namely the temperature difference value between the temperature measuring point and the thermistor 1 body for measurement, the signals of the follower circuit in the temperature compensation circuit group and the output end of the thermistor signal processing circuit group for measurement are connected to the addition circuit in the temperature compensation circuit group together, namely the temperature of the thermistor 1 body for measurement is summed with the temperature difference values of the temperature measuring point and the thermistor 1 body for measurement, the output signal of the addition circuit, namely the temperature value of the temperature measuring point, can weaken the influence of the thermal resistance from the temperature measuring point to the thermistor body for measurement on the processing error, can more accurately obtain the temperature value of the temperature measuring point, meanwhile, the adjustable divider circuit is adopted, can be adjusted according to the actual application condition, the application range is improved, and the constant current circuit is used for supplying power to, facilitating subsequent linear electrical signal processing.
The foregoing is only a preferred embodiment of the present invention; the scope of the invention is not limited thereto. Any person skilled in the art should be able to cover the technical scope of the present invention by equivalent or modified solutions and modifications within the technical scope of the present invention.
Claims (10)
1. The utility model provides a high accuracy temperature measurement circuit of area compensation function, is including measuring with thermistor signal processing circuit group, compensation with thermistor signal processing circuit group and temperature compensation circuit group, its characterized in that: the thermistor signal processing circuit group for measurement comprises a thermistor (1) for measurement, a constant current circuit, a following circuit and a subtraction circuit; the thermistor signal processing circuit group for compensation comprises a thermistor (14) for compensation, a constant current circuit, a following circuit and a subtraction circuit; the temperature compensation circuit group comprises a subtraction circuit, an adjustable voltage division circuit, a following circuit and an addition circuit;
the thermistor (1) for measurement is arranged at a temperature measuring point, the thermistor (14) for compensation is arranged on a temperature measuring plate, two ends of the thermistor (1) for measurement are respectively connected to a constant current circuit of a thermistor signal processing circuit group for measurement, one end of the thermistor (1) for measurement is connected with a non-inverting input end of a subtraction circuit in the thermistor signal processing circuit group for measurement, the other end of the thermistor (1) for measurement is connected with an inverting input end of the subtraction circuit in the thermistor signal processing circuit group for measurement through a following circuit in the thermistor signal processing circuit group for measurement, and a temperature signal corresponding to the thermistor (1) for measurement is obtained after the processing of the subtraction circuit;
the output end of the subtraction circuit in the thermistor signal processing circuit group for measurement is respectively connected with the non-inverting input end and the adding circuit of the subtraction circuit in the temperature compensation circuit group, two ends of the thermistor (14) for compensation are respectively connected with the constant current circuit of the thermistor signal processing circuit group for compensation, one end of the thermistor (14) for compensation is connected with the non-inverting input end of the subtraction circuit in the thermistor signal processing circuit group for compensation, the other end of the thermistor (14) for compensation is connected with the inverting input end of the subtraction circuit in the thermistor signal processing circuit group for compensation through the following circuit in the thermistor signal processing circuit group for compensation, and a temperature signal corresponding to the thermistor (14) for compensation is obtained after the processing of the subtraction circuit;
the output end of the subtraction circuit in the thermistor signal processing circuit group for compensation is connected with the inverted input end of the subtraction circuit in the temperature compensation circuit group, the output end of the subtraction circuit in the temperature compensation circuit group is divided by the adjustable voltage division circuit and then is amplified by the following circuit, namely the temperature difference between the temperature measuring point and the temperature of the thermistor (1) body for measurement, the output end of the subtraction circuit in the thermistor signal processing circuit group for measurement and the output end of the following circuit in the temperature compensation circuit group are both connected with the non-inverting input end of the addition circuit in the temperature compensation circuit group, the addition circuit in the temperature compensation circuit group is used for measuring the temperature of the thermistor (1) body, and summing the temperature difference value of the temperature measuring point and the temperature difference value of the thermistor (1) body for measurement, wherein the output signal of the summing circuit is the temperature value of the temperature measuring point.
2. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the constant current circuit comprises a constant current operational amplifier (6), the non-inverting input end of the constant current operational amplifier (6) is connected with a non-inverting end matching resistor (5), one end of the in-phase end matching resistor (5) far away from the constant current operational amplifier (6) is connected with a filter capacitor (4), the filter capacitor (4) is connected with a voltage stabilizing chip (3) in parallel, the filter capacitor (4) carries out filtering processing on the voltage stabilizing chip (3), the feedback end of the voltage stabilizing chip (3) is connected with the current limiting resistor (2), one end of the current limiting resistor (2) far away from the voltage stabilizing chip (3) is connected with a power supply, a constant current sampling resistor (7) is connected between the inverting input end of the constant current operational amplifier (6) and the ground potential, and an electric element is connected between the inverting input end of the constant current operational amplifier (6) and the output end of the constant current operational amplifier (6).
3. The high-precision temperature measuring circuit with the compensation function according to claim 1 is characterized in that the model of the voltage stabilizing chip (3) is T L431, the voltage stabilizing chip (3) has excellent performance, and the price of the voltage stabilizing chip (3) is reduced.
4. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the following circuit comprises a following operational amplifier (8), wherein the in-phase input end of the following operational amplifier (8) is connected with the signal end of the previous circuit, the reverse phase input end of the following operational amplifier (8) is connected with the output end of the following operational amplifier (8), and the output end of the following operational amplifier (8) is connected with the input end of the next circuit, so that the voltage signal of the previous circuit can be amplified conveniently.
5. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the subtraction circuit comprises a subtraction operational amplifier (12), wherein a non-inverting input end of the subtraction operational amplifier (12) is connected with an in-phase upper voltage-dividing resistor (9), a non-inverting lower voltage-dividing resistor (10) is connected between the non-inverting input end of the subtraction operational amplifier (12) and the in-phase upper voltage-dividing resistor (9), the non-inverting lower voltage-dividing resistor (10) is grounded, the non-inverting upper voltage-dividing resistor (9) is connected with an output end of a previous circuit, an inverting input end of the subtraction operational amplifier (12) is connected with an inverting input resistor (11), the inverting input resistor (11) is connected with an output end of the previous circuit, an output end of the subtraction operational amplifier (12) is connected with a feedback resistor (13), and one end, far away from the output end of the subtraction operational amplifier (12), of the feedback resistor (13) is connected with an, the processing precision of the voltage signal in the input operational amplifier (12) is improved.
6. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: adjustable bleeder circuit includes partial pressure adjustable resistor (15), and the one end of going up partial pressure adjustable resistor (15) is connected with the output of subtraction circuit in the temperature compensation circuit group, goes up partial pressure adjustable resistor (15) and keeps away from the one end of subtraction circuit in the temperature compensation circuit group and is connected with the input of following the circuit in the temperature compensation circuit group, go up and be connected with bleeder resistor (16) down between the following circuit in partial pressure adjustable resistor (15) and the temperature compensation circuit group, and bleeder resistor (16) keep away from the one end ground connection of last partial pressure adjustable resistor (15) down, adjust the resistance of going up partial pressure adjustable resistor (15) and bleeder resistor (16) down according to the practical application operating mode, improve temperature measuring circuit's application scope.
7. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the summing circuit comprises a summing operational amplifier (21), wherein a first in-phase resistor (17) and a second in-phase resistor (18) are connected to the in-phase input end of the summing operational amplifier (21), the first in-phase resistor (17) is connected with the output end of a subtraction circuit in a thermistor signal processing circuit group for measurement, the second in-phase resistor (18) is connected with the output end of a following circuit in a temperature compensation circuit group, the inverting input end of the summing operational amplifier (21) is connected with a summing inverting lower divider resistor (19), one end, far away from the summing operational amplifier (21), of the summing inverting lower divider resistor (19) is grounded, a summing feedback resistor (20) is connected between the output end and the inverting input end of the summing operational amplifier (21), and therefore the processing precision of voltage signals input into the summing operational amplifier (21) is improved conveniently.
8. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the constant current operational amplifier (6), the following operational amplifier (8), the subtraction operational amplifier (12) and the addition operational amplifier (21) are all powered by the same power supply, and the circuit structure is simplified.
9. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the in-phase upper voltage-dividing resistor (9), the in-phase lower voltage-dividing resistor (10), the reverse-phase input resistor (11) and the feedback resistor (13) are identical in resistance value, and the accuracy of the subtraction circuit is guaranteed.
10. The high-precision temperature measuring circuit with the compensation function according to claim 1, wherein: the first in-phase resistor (17), the second in-phase resistor (18), the addition reverse-phase lower divider resistor (19) and the addition feedback resistor (20) have the same resistance value, and the accuracy of the addition circuit is guaranteed.
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