CN210037001U - Precision temperature measurement system applied to biphenyl heating box in spinning elasticizer - Google Patents
Precision temperature measurement system applied to biphenyl heating box in spinning elasticizer Download PDFInfo
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- CN210037001U CN210037001U CN201920805782.4U CN201920805782U CN210037001U CN 210037001 U CN210037001 U CN 210037001U CN 201920805782 U CN201920805782 U CN 201920805782U CN 210037001 U CN210037001 U CN 210037001U
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Abstract
The utility model discloses a be applied to accurate temperature measurement system of biphenyl heating cabinet among weaving elasticizer relates to the temperature measurement field, include: at least two three-wire system PT100 temperature sensors, an analog switch and a measuring circuit; the three-wire system PT100 temperature sensor is connected to a measuring circuit through a corresponding analog switch; the measuring circuit comprises a first constant current source, a second constant current source, a third constant current source, a reference circuit, a biasing circuit, a differential instrument amplifier, a homodromous amplifier, a calibration circuit and an MCU; each analog switch is equivalent to a first analog switch and a second analog switch, and the first analog switch and the second analog switch respectively comprise two paths of switches. The three constant current sources are used as the same reference, errors of a power supply system, reference errors and measurement errors of MCU analog quantity are effectively eliminated, automatic calibration measurement is adopted, manual calibration is not needed, differential instruments are adopted for operational amplifier, common mode interference can be effectively eliminated, and the device is suitable for working conditions of the textile industry.
Description
Technical Field
The utility model belongs to the technical field of the temperature measurement and specifically relates to a be applied to accurate temperature measurement system of biphenyl heating cabinet among weaving elasticizer.
Background
The sensor model of the conventional temperature measurement in the present weaving elasticizer biphenyl heating cabinet is mostly platinum resistance PT100, the temperature measuring point is many, and the distance of temperature sensor and controller is far away for line loss on the PT100 is serious, and static on the elasticizer is very serious in addition, and common mode interference is great, and the degree of difficulty of temperature measurement is also improved greatly.
The measuring method of the PT100 temperature sensor in the biphenyl heating box mainly comprises a bridge type temperature measuring method and a single constant current source three-wire system temperature measuring method, and a common bridge type temperature measuring circuit has the advantages that the PT100 sensor is connected with the measuring circuit by three wires, the equal wire lengths on two sides of the PT100 sensor are respectively added on bridge arms on two sides, so that errors caused by wire resistance can be counteracted, but the measuring errors of the system cannot be eliminated; meanwhile, the single constant current source is required to measure the line resistance of the three-wire system PT100 by repeatedly switching the analog switch, so that the measurement speed is reduced. The existing temperature measuring method can obtain better measuring precision within a certain temperature range, once the temperature is beyond the temperature range, the temperature drift characteristics of each device can seriously influence the measuring precision, and the working environment of a spinning machine is necessarily high temperature, high oil and high static electricity, so that the influence on a circuit is larger.
SUMMERY OF THE UTILITY MODEL
The utility model aims at the above-mentioned problem and technical demand, a be applied to accurate temperature measurement system of biphenyl heating cabinet among weaving elasticizer is proposed.
The technical scheme of the utility model as follows:
the utility model provides a be applied to accurate temperature measurement system of biphenyl heating cabinet among weaving elasticizer, includes: the system comprises at least two three-wire system PT100 temperature sensors, analog switches and a measuring circuit, wherein the number of the analog switches is equal to that of the three-wire system PT100 temperature sensors; the three-wire system PT100 temperature sensor is connected to the measuring circuit through a corresponding analog switch;
the measuring circuit comprises a first constant current source, a second constant current source, a third constant current source, a reference circuit, a biasing circuit, a differential instrument amplifier, a homodromous amplifier, a calibration circuit and an MCU (microprogrammed control unit); each analog switch is equivalent to a first analog switch and a second analog switch, and the first analog switch and the second analog switch respectively comprise two paths of switches;
a first output of the three-wire system PT100 temperature sensor is respectively connected with a first switch in the first analog switch and the second analog switch, a second output of the three-wire system PT100 temperature sensor is respectively connected with a second switch in the first analog switch and the second analog switch, and a third output of the three-wire system PT100 temperature sensor is grounded;
one end of the first constant current source is connected with a first switch of the first analog switch, one end of the second constant current source is connected with a second switch of the first analog switch, and the other ends of the first constant current source and the second constant current source are respectively connected with the third constant current source; the third constant current source is respectively connected with the reference circuit and the bias circuit, the reference circuit is respectively connected with the bias circuit and the MCU, the bias circuit is connected with the equidirectional amplifier, and the equidirectional amplifier is connected with the MCU; the two switches of the second analog switch are connected with the differential instrument amplifier, and the differential instrument amplifier is connected with the equidirectional amplifier; the two switches of the first analog switch and the second analog switch are both connected with the calibration circuit, and the calibration circuit is connected with the MCU.
The further technical scheme is as follows: the first constant current source flows into the positive terminal of the three-wire system PT100 temperature sensor through the first analog switch, the second constant current source flows into the negative terminal of the three-wire system PT100 temperature sensor through the first analog switch, the third constant current source generates a constant voltage through the reference circuit to be supplied to the first constant current source and the second constant current source as a reference, and the reference circuit also supplies a reference voltage to an ADC digital-to-analog converter of the MCU.
The further technical scheme is as follows: and the positive end and the negative end of the three-wire PT100 temperature sensor pass through the second analog switch to the differential instrument amplifier, and enter the same-direction amplifier together with the bias circuit, and the same-direction amplifier amplifies signals and then sends the amplified signals to the MCU to be converted into digital quantity for system control.
The further technical scheme is as follows: the three-wire PT100 temperature sensor comprises a thermistor, a first lead internal resistance, a second lead internal resistance and a third lead internal resistance; the first lead internal resistance, the second lead internal resistance and the third lead internal resistance are connected in parallel, and the thermistor is connected with the first lead internal resistance in series; the first lead internal resistance leads out a first output, the second lead internal resistance leads out a second output, and the third lead internal resistance leads out a third output.
The further technical scheme is as follows: the calibration circuit switches a calibration source and a standard resistor through the first analog switch and the second analog switch;
the calibration of the calibration circuit at least comprises the calibration of a temperature zero position, a first constant current source current, a second constant current source current, zero position input of an instrument amplifier and amplification times of a homodromous amplifier.
The further technical scheme is as follows: the model number of the analog switch is HEF4052BT (NXP).
The utility model has the beneficial technical effects that:
the application provides a be applied to accurate temperature measurement system of biphenyl heating cabinet in weaving elasticizer adopts three constant current source with the benchmark, effectual elimination electrical power generating system's error, MCU analog quantity's reference error and measuring error, temperature measurement speed is one time faster than single constant current source measurement method, in addition, this accurate temperature measurement system adopts automatic calibration to measure, need not artifical calibration, adopt differential instrument fortune to put, can effectively eliminate common mode interference, be applicable to textile industry's operating mode.
Drawings
Fig. 1 is a block diagram of a precision temperature measurement system applied to a biphenyl heating box in a textile elasticizer according to an embodiment of the present invention.
Fig. 2 is a block diagram of a measurement circuit according to an embodiment of the present invention.
Fig. 3 is a schematic circuit diagram of a measurement circuit according to an embodiment of the present invention.
Detailed Description
The following describes the embodiments of the present invention with reference to the accompanying drawings.
The embodiment of the utility model provides a to the not enough of conventional measurement mode, provide new accurate temperature measurement system, measuring speed is faster than single constant current source measurement.
Fig. 1 is a structural block diagram of a precision temperature measurement system applied to a biphenyl heating box in a textile elasticizer provided by an embodiment of the present invention, as shown in fig. 1, the precision temperature measurement system may include: at least two three-wire system PT100 temperature sensors 1, analog switches 2 equal in number to the three-wire system PT100 temperature sensors 1, and a measurement circuit 3; the three-wire system PT100 temperature sensor 1 is connected to the measurement circuit 3 through the corresponding analog switch 2.
Illustratively, as shown in fig. 1, in practical application, a joint of the biphenyl heating box usually has 24 three-wire PT100 temperature sensors 1, and the 24 three-wire PT100 temperature sensors 1 can share one measuring circuit 3 and are switched by using 24 sets of analog switches 2.
Optionally, the analog switch has a model number HEF4052BT (NXP).
Referring to fig. 2 in combination, the measurement circuit 3 includes a first constant current source 4, a second constant current source 5, a third constant current source 6, a reference circuit 7, a bias circuit 8, a differential instrument amplifier 9, a homodyne amplifier 10, a calibration circuit 11, and an MCU 12. Each analog switch 2 in fig. 1 is equivalent to the first analog switch 13 and the second analog switch 14 in fig. 2, and the first analog switch 13 and the second analog switch 14 respectively include two switches.
As shown in fig. 2, the first output of the three-wire PT100 temperature sensor 1 is connected to the first switches of the first and second analog switches 13 and 14, respectively, the second output is connected to the second switches of the first and second analog switches 13 and 14, respectively, and the third output is grounded.
One end of the first constant current source 4 is connected with a first switch of the first analog switch 13, one end of the second constant current source 5 is connected with a second switch of the first analog switch 13, and the other ends of the first constant current source 4 and the second constant current source 5 are respectively connected with the third constant current source 6; the third constant current source 6 is respectively connected with a reference circuit 7 and a bias circuit 8, the reference circuit 7 is respectively connected with the bias circuit 8 and an MCU 12, the bias circuit 8 is connected with a homodromous amplifier 10, and the homodromous amplifier 10 is connected with the MCU 12; two switches of the second analog switch 14 are connected with a differential instrument amplifier 9, and the differential instrument amplifier 9 is connected with a homodromous amplifier 10; two switches of the first analog switch 13 and the second analog switch 14 are both connected with the calibration circuit 11, and the calibration circuit 11 is connected with the MCU 12.
The first constant current source 4 flows into the positive terminal of the three-wire system PT100 temperature sensor 1 through the first analog switch 13, the second constant current source 5 flows into the negative terminal of the three-wire system PT100 temperature sensor 1 through the first analog switch 13, the third constant current source 6 generates a constant voltage through the reference circuit 7 to be supplied to the first constant current source 4 and the second constant current source 5 as a reference, and the reference circuit 7 also supplies a reference voltage to the ADC digital-to-analog converter of the MCU 12. The three constant current sources share one reference circuit, all parameters are consistent, the influence of power supply system fluctuation on bias voltage can be eliminated by the same reference source, the temperature fluctuation of devices can be offset by devices of the same type, and the proportional relation exists among the devices.
The positive end and the negative end of the three-wire system PT100 temperature sensor 1 pass through a second analog switch 14 to a differential instrument amplifier 9, and then enter a homodromous amplifier 10 together with a bias circuit 8, and the homodromous amplifier 10 amplifies a signal and then sends the signal to an MCU 12 to be converted into digital quantity for system control.
The embodiment of the utility model provides a precision temperature measurement system has the self calibration circuit part, and calibration circuit 11 switches calibration source and standard resistance through first analog switch 13 and second analog switch 14; the calibration of the calibration circuit 11 at least comprises the calibration of a temperature zero position, a first constant current source current, a second constant current source current, zero position input of an instrument amplifier and amplification of a homodromous amplifier.
Optionally, as shown in fig. 2, the three-wire PT100 temperature sensor 1 includes a thermistor Rt, a first internal resistance R1#, a second internal resistance R2#, and a third internal resistance R3 #; the first lead internal resistance R1#, the second lead internal resistance R2#, and the third lead internal resistance R3# are connected in parallel, and the thermistor Rt is connected with the first lead internal resistance R1# in series; the first internal resistance R1# leads to a first output, the second internal resistance R2# leads to a second output, and the third internal resistance R3# leads to a third output.
Referring to fig. 3 in combination, which shows a schematic circuit diagram of the measurement circuit, the last voltage Vout ═ Vo 1-Vb, Vb is a bias voltage, Vo1 is an output voltage of the differential instrumentation amplifier, Vo1 ═ Av (Vin + -Vin-), Av is an amplification factor of the differential instrumentation amplifier, (Vin + -Vin-) is a voltage difference between the positive terminal and the negative terminal of PT100, Vin + ═ I1 × (R1# + Rt + R3#) + I2 × R3#, Vin- ═ I2 × (R2# + R3#) + I1 × R3, I1 is a first constant current source, and I2 is a second constant current source. The materials of the lead wires of the PT100 temperature sensor in the three-wire system are consistent, so that the wire resistance R1# -R2 # -R3 #; the first constant current source and the second constant current source both refer to the same reference power supply, and the device parameters are consistent, so that the input formula of I1 (I2) is substituted by I (Rt ═ Vout-Vb) ÷ (Av × I). Vb, Av, I are fixed values in a short time, Vout is a variable.
Illustratively, as shown in table 1, values of various devices in the schematic circuit diagram shown in fig. 3 are shown.
TABLE 1
For key resistors (R1, R2, R4, R5, R7, R16, R8, R10, R11, R12, R13, R15, R17, R18, R19, R20, R28, R29 and R30) in a measuring circuit, low-temperature drift precision resistors are adopted, so that the system has the lowest temperature drift and time drift in the whole service temperature region.
When 4052_ a is 1 and 4052_ B is 1, Vin + ═ 0V, Vin ═ 0V, that is, differential instrumentation amplifier input 0V, the value Vb can be calculated in the calibration circuit; when 4052_ a is 0 and 4052_ B is 1, the value I1 can be calculated; when 4052_ a and 4052_ B are 0, the Av value can be calculated.
Illustratively, as shown in table 2, a truth table of signals 4052_ a, 4052_ B in the calibration circuit is shown.
TABLE 2
| No. | 4052_A | 4052_B | Description of the |
| 1 | 0 | 0 | Zero temperature of 100.0 omega-0.0 |
| 2 | 0 | 1 | First constant current source of 200.0 omega-266.6 |
| 3 | 1 | 0 | 200.0 omega-266.6 deg.C second constant |
| 4 | 1 | 1 | Instrumentation amplifier input 0V value |
To the utility model provides a precision temperature measurement system, its specific temperature measurement flow is: vb, Av and I can be obtained through the calibration circuit, and the analog switches of the loop are closed; and then, opening the first analog switch to measure Vout, calculating the resistance value of the PT100 sensor of the 1 st channel, looking up a table to obtain a temperature value, then opening the second analog switch to measure Vout, calculating the resistance value of the PT100 sensor of the 2 nd channel, looking up the table to obtain the temperature value, and so on until the temperature measurement of the 24 th channel is finished and the current cycle is completed.
The traditional single constant current source measuring method can finish basic voltage difference measurement only by measuring internal resistance of two lines, and the first constant current source and the second constant current source in the precise temperature measuring system can be read in at one time, so that the temperature measuring speed is doubled. The problem that the error can not be eliminated when reference voltage, electrical power generating system instantaneous change in traditional single constant current source measurement method has still been solved simultaneously, is the linkage effect on the precision temperature measurement system hardware circuit that this application provided, and mutual dragging, the change of system's power can not get into the measurement channel, and the change of reference voltage also can be offset.
What has been described above is only the preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and scope of the present invention are to be considered as included within the scope of the present invention.
Claims (6)
1. The utility model provides a be applied to accurate temperature measurement system of biphenyl heating cabinet among weaving elasticizer which characterized in that includes: the system comprises at least two three-wire system PT100 temperature sensors, analog switches and a measuring circuit, wherein the number of the analog switches is equal to that of the three-wire system PT100 temperature sensors; the three-wire system PT100 temperature sensor is connected to the measuring circuit through a corresponding analog switch;
the measuring circuit comprises a first constant current source, a second constant current source, a third constant current source, a reference circuit, a biasing circuit, a differential instrument amplifier, a homodromous amplifier, a calibration circuit and an MCU (microprogrammed control unit); each analog switch is equivalent to a first analog switch and a second analog switch, and the first analog switch and the second analog switch respectively comprise two paths of switches;
a first output of the three-wire system PT100 temperature sensor is respectively connected with a first switch in the first analog switch and the second analog switch, a second output of the three-wire system PT100 temperature sensor is respectively connected with a second switch in the first analog switch and the second analog switch, and a third output of the three-wire system PT100 temperature sensor is grounded;
one end of the first constant current source is connected with a first switch of the first analog switch, one end of the second constant current source is connected with a second switch of the first analog switch, and the other ends of the first constant current source and the second constant current source are respectively connected with the third constant current source; the third constant current source is respectively connected with the reference circuit and the bias circuit, the reference circuit is respectively connected with the bias circuit and the MCU, the bias circuit is connected with the equidirectional amplifier, and the equidirectional amplifier is connected with the MCU; the two switches of the second analog switch are connected with the differential instrument amplifier, and the differential instrument amplifier is connected with the equidirectional amplifier; the two switches of the first analog switch and the second analog switch are both connected with the calibration circuit, and the calibration circuit is connected with the MCU.
2. The precision temperature measuring system applied to the biphenyl heating box in the textile elasticizer according to claim 1, wherein the first constant current source flows into a positive terminal of the three-wire system PT100 temperature sensor through the first analog switch, the second constant current source flows into a negative terminal of the three-wire system PT100 temperature sensor through the first analog switch, the third constant current source generates a constant voltage through the reference circuit to be provided to the first constant current source and the second constant current source as a reference, and the reference circuit further provides a reference voltage to an ADC digital-to-analog converter of the MCU.
3. The precise temperature measurement system applied to the biphenyl heating box in the textile elasticizer according to claim 1, wherein the positive end and the negative end of the three-wire PT100 temperature sensor pass through the second analog switch to the differential instrumentation amplifier, and then enter the same-direction amplifier together with the bias circuit, and the same-direction amplifier amplifies the signals and then sends the amplified signals to the MCU to be converted into digital quantity for system control.
4. The precise temperature measurement system applied to the biphenyl heating box in the textile elasticizer according to claim 1, wherein the three-wire system PT100 temperature sensor comprises a thermistor, a first lead internal resistance, a second lead internal resistance and a third lead internal resistance; the first lead internal resistance, the second lead internal resistance and the third lead internal resistance are connected in parallel, and the thermistor is connected with the first lead internal resistance in series; the first lead internal resistance leads out a first output, the second lead internal resistance leads out a second output, and the third lead internal resistance leads out a third output.
5. The precise temperature measurement system applied to the biphenyl heating box in the textile elasticizer according to claim 1, wherein the calibration circuit switches the calibration source and the standard resistor through the first analog switch and the second analog switch;
the calibration of the calibration circuit at least comprises the calibration of a temperature zero position, a first constant current source current, a second constant current source current, zero position input of an instrument amplifier and amplification times of a homodromous amplifier.
6. The precise temperature measurement system applied to the biphenyl heating box in the textile elasticizer according to any one of claims 1 to 5, wherein the model of the analog switch is HEF4052 BT.
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| CN201920805782.4U CN210037001U (en) | 2019-05-30 | 2019-05-30 | Precision temperature measurement system applied to biphenyl heating box in spinning elasticizer |
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| CN201920805782.4U CN210037001U (en) | 2019-05-30 | 2019-05-30 | Precision temperature measurement system applied to biphenyl heating box in spinning elasticizer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110108380A (en) * | 2019-05-30 | 2019-08-09 | 无锡市百川科技股份有限公司 | A kind of precise temperature measurement system applied to biphenyl heater box in weaving elasticizer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110108380A (en) * | 2019-05-30 | 2019-08-09 | 无锡市百川科技股份有限公司 | A kind of precise temperature measurement system applied to biphenyl heater box in weaving elasticizer |
| CN110108380B (en) * | 2019-05-30 | 2024-06-14 | 无锡市百川科技股份有限公司 | Be applied to accurate temperature measurement system of diphenyl heating cabinet in weaving elasticizer |
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