CN211347137U - Temperature measuring circuit of three-wire thermal resistor - Google Patents
Temperature measuring circuit of three-wire thermal resistor Download PDFInfo
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- CN211347137U CN211347137U CN201922392530.6U CN201922392530U CN211347137U CN 211347137 U CN211347137 U CN 211347137U CN 201922392530 U CN201922392530 U CN 201922392530U CN 211347137 U CN211347137 U CN 211347137U
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- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 238000009529 body temperature measurement Methods 0.000 claims abstract description 16
- 239000003990 capacitor Substances 0.000 claims description 30
- 230000001629 suppression Effects 0.000 claims description 4
- 230000001052 transient effect Effects 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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Abstract
The embodiment of the utility model provides a temperature measurement circuit of three-wire system thermal resistor, including analog-to-digital converter, precision resistor and MCU; the analog-digital converter comprises a constant current source, the digital-analog converter directly provides stable current for the three-wire heating resistor, the voltage of the three-wire heating resistor is collected through the voltage collecting end, and then the resistance value of the heating resistor in the three-wire heating resistor is calculated. The whole circuit is simple in structure, and the voltages at the two ends of the precision resistor are used as the reference voltage of the analog-to-digital converter, so that the influence of the change of the constant current source on the final calculation result is eliminated.
Description
Technical Field
The utility model relates to a thermal resistance technical field, more specifically say, relate to the temperature measurement circuit of three-wire system thermal resistance.
Background
Thermal resistance is one of the most commonly used temperature detectors in the medium and low temperature regions. The principle of thermal resistance measurement is based on the property that the resistance of a conductor or semiconductor changes with temperature to measure temperature and temperature-related parameters. The thermal resistor is mostly made of pure metal materials, the most widely used at present are platinum and copper, and the thermal resistor is made of materials such as nickel, manganese and rhodium. Thermal resistors typically require a resistance signal to be transmitted through a lead to a computer control or other secondary instrument.
The conventional three-wire thermal resistor temperature measuring method mainly includes two methods, namely a bridge method and a constant current source method. The hardware circuit of the bridge method is simple but the anti-interference capability is weak; the hardware circuit of the constant current source method is complicated.
SUMMERY OF THE UTILITY MODEL
In view of this, the present invention provides a temperature measuring circuit of three-wire thermal resistor, which is intended to simplify the hardware circuit of the constant current source method.
In order to achieve the above object, the following solutions are proposed:
a temperature measurement circuit of a three-wire system thermal resistor, comprising: the device comprises an analog-to-digital converter, a precision resistor and an MCU;
the analog-to-digital converter comprises a constant current source;
the constant current source output end of the analog-to-digital converter and the first voltage acquisition end of the analog-to-digital converter are both connected with one end of a first lead of the three-wire heating resistor, and the other end of the first lead is connected with one end of the heating resistor of the three-wire heating resistor;
a second voltage acquisition end of the analog-to-digital converter is connected with one end of a second lead of the three-wire heating resistor, a third voltage acquisition end of the analog-to-digital converter is connected with one end of a third lead of the three-wire heating resistor, and the other end of the second lead and the other end of the third lead are both connected with the other end of the heating resistor;
one end of the precision resistor is connected with a power ground, and the other end of the precision resistor is respectively connected with the reference voltage input end and one end of the third wire;
the MCU is in communication connection with the analog-to-digital converter.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes: a first resistor and a diode connected between the output end of the constant current source and one end of the first wire;
the negative pole of the diode is connected with one end of the first lead, the positive pole of the diode is connected with one end of the first resistor, and the other end of the first resistor is connected with the output end of the constant current source.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
the second resistor is connected between the first voltage acquisition end and one end of the first lead; and the number of the first and second groups,
and one end of the first capacitor is connected with the first voltage acquisition end, and the other end of the first capacitor is connected with a power ground.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
a third resistor connected between the second voltage acquisition end and one end of the second wire; and the number of the first and second groups,
and the second capacitor is connected with the second voltage acquisition end at one end and connected with a power ground at the other end.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
and one end of the third capacitor is connected with the first voltage acquisition end, and the other end of the third capacitor is connected with the second voltage acquisition end.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
and the fourth resistor is connected between the third voltage acquisition end and one end of the third lead.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
the fifth resistor is connected between the reference voltage input end and the other end of the precision resistor; and the number of the first and second groups,
and one end of the fourth capacitor is connected with the reference voltage input end, and the other end of the fourth capacitor is connected with a power ground.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
and the fifth capacitor is connected with the precision resistor in parallel.
Optionally, the temperature measuring circuit of the three-wire thermal resistor further includes:
a transient suppression diode in parallel with the precision resistor.
Optionally, the MCU is connected to the analog-to-digital converter through an SPI bus.
Compared with the prior art, the technical scheme of the utility model have following advantage:
the temperature measuring circuit of the three-wire thermal resistor comprises an analog-to-digital converter, a precision resistor and an MCU (microprogrammed control unit); the analog-digital converter comprises a constant current source, the digital-analog converter directly provides stable current for the three-wire heating resistor, the voltage of the three-wire heating resistor is collected through the voltage collecting end, and then the resistance value of the heating resistor in the three-wire heating resistor is calculated. The whole circuit is simple in structure, and the voltages at the two ends of the precision resistor are used as the reference voltage of the analog-to-digital converter, so that the influence of the change of the constant current source on the final calculation result is eliminated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic diagram of a temperature measuring circuit of a three-wire thermal resistor according to an embodiment of the present invention;
fig. 2 is a schematic diagram of another temperature measuring circuit of a three-wire thermal resistor according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
The present embodiment provides a temperature measuring circuit of a three-wire thermal resistor, and referring to fig. 1, the temperature measuring circuit 11 of the three-wire thermal resistor includes an analog-to-digital converter (ADC), a precision resistor RREFAnd an MCU. RRTDIs a thermal resistor of the three-wire system thermal resistor 12, Rwire1、Rwire2、Rwire3Three-wire lead electricity of three-wire system thermal resistor 12And (4) blocking.
The ADC includes a constant current source. The constant current source output end a of the ADC and the first voltage acquisition end B of the ADC are both connected to one end of the first wire of the three-wire heating resistor 12. The other end of the first lead and the thermal resistor RRTDIs connected at one end. The second voltage collecting terminal C of the ADC is connected to one end of the second wire of the three-wire heating resistor 12. The third voltage acquisition terminal D of the ADC is connected to one end of the third wire of the three-wire heating resistor 13. The other end of the second lead and the other end of the third lead are connected with a thermal resistor RRTDThe other end of the connecting rod is connected.
Precision resistor RREFOne end of the power supply is connected with a power ground; precision resistor RREFAnd the other end thereof is connected to the reference voltage input terminal REF + and one end of the third wire, respectively. The MCU is in communication connection with the ADC.
The first voltage acquisition end B, the second voltage acquisition end C and the third voltage acquisition end D of the ADC are all high-resistance inputs, and no current flows into the ADC; therefore, the current output by the constant current source passes through the wire resistance R of the first wirewire1Thermal resistor RRTDAnd a wire resistance R of the third wirewire3And a precision resistor RREFBack to the power ground. Precision resistor RREFFor generating a reference voltage for the ADC. During working, the MCU controls the ADC to collect the voltage between the first voltage collecting end B and the second voltage collecting end C, and then controls the ADC to collect the voltage between the second voltage collecting end C and the third voltage collecting end D; further calculate the thermal resistance RRTDThe resistance value of (c).
Actual voltage value UADCAnd the acquired Code value Code transmitted by the ADC to the MCU is in a relation of formula (1):
wherein I is the current value of the constant current source, UREFIs the reference voltage of the ADC.
Actual voltage U between first voltage collection terminal B and second voltage collection terminal CBCAnd the acquisition code value C transmitted to the MCU by the ADCBCThe relationship between them is as in formula (2):
actual voltage U between second voltage collection terminal C and third voltage collection terminal DCDAnd the acquisition code value C transmitted to the MCU by the ADCCDThe relationship between them is as in formula (3):
in this example it is considered that Rwire1、Rwire2And Rwire3The resistance values are the same. Obtained from equations (2) and (3):
the present embodiment provides another temperature measurement circuit of a three-wire thermal resistor, and referring to fig. 2, compared with the temperature measurement circuit of a three-wire thermal resistor shown in fig. 1, the temperature measurement circuit further includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a diode D, and a transient suppression diode TVS. The ADC is specifically of a model AD7124-8, in which 4 denotes a constant current source output terminal a, 5 denotes a first voltage collection terminal B, 6 denotes a second voltage collection terminal C, 21 denotes a third voltage collection terminal D, and 12 denotes a reference voltage input terminal REF +.
The first resistor R1 and the diode D are connected between the constant current source output terminal a and one end of the first wire. The cathode of the diode D is connected with one end of the first lead, the anode of the diode D is connected with one end of the first resistor R1, and the other end of the first resistor R1 is connected with the output end A of the constant current source.
The second resistor R2 is connected between the first voltage acquisition end B and one end of the first lead; one end of the first capacitor C1 is connected to the first voltage collecting terminal B, and the other end of the first capacitor C1 is connected to the power ground.
The third resistor R3 is connected between the second voltage acquisition end C and one end of the second lead; one end of the second capacitor C2 is connected to the second voltage collecting terminal C, and the other end of the second capacitor C2 is connected to the power ground.
One end of the third capacitor C3 is connected to the first voltage collecting terminal B, and the other end of the third capacitor C3 is connected to the second voltage collecting terminal C.
The fourth resistor R4 is connected between the third voltage collecting terminal D and one end of the third wire.
A fifth resistor R5 connected between the reference voltage input terminal REF + and the precision resistor RREFThe other end of (a); one end of the fourth capacitor C4 is connected to the reference voltage input terminal REF +, and the other end of the fourth capacitor C4 is connected to the power ground.
A fifth capacitor C5 and a precision resistor RREFAnd (4) connecting in parallel. Transient suppression diode TVS and precision resistor RREFAnd (4) connecting in parallel. The MCU and the ADC are connected via an SPI bus (not shown). In one embodiment the constant current source provides a current value of 0.75 mA.
For each resistor in the diagram, an optional form is given only by way of example, in practical application, each resistor may not only be a single resistor, but also be replaced by a plurality of resistors connected in series, a plurality of resistors connected in parallel, or a plurality of resistors connected in series and parallel according to actual requirements, and this time is not specifically limited, and the present invention is within the protection scope of the present invention.
In this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a device that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such device. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of additional like elements in a device that comprises the element.
In the present specification, the emphasis points of the embodiments are different from those of the other embodiments, and the same and similar parts among the embodiments may be referred to each other.
The above description of the disclosed embodiments of the invention enables one skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A temperature measurement circuit of a three-wire system thermal resistor, comprising: the device comprises an analog-to-digital converter, a precision resistor and an MCU;
the analog-to-digital converter comprises a constant current source;
the constant current source output end of the analog-to-digital converter and the first voltage acquisition end of the analog-to-digital converter are both connected with one end of a first lead of the three-wire heating resistor, and the other end of the first lead is connected with one end of the heating resistor of the three-wire heating resistor;
a second voltage acquisition end of the analog-to-digital converter is connected with one end of a second lead of the three-wire heating resistor, a third voltage acquisition end of the analog-to-digital converter is connected with one end of a third lead of the three-wire heating resistor, and the other end of the second lead and the other end of the third lead are both connected with the other end of the heating resistor;
one end of the precision resistor is connected with a power ground, and the other end of the precision resistor is respectively connected with a reference voltage input end and one end of the third wire;
the MCU is in communication connection with the analog-to-digital converter.
2. The temperature measurement circuit of three-wire thermal resistor according to claim 1, further comprising: a first resistor and a diode connected between the output end of the constant current source and one end of the first wire;
the negative pole of the diode is connected with one end of the first lead, the positive pole of the diode is connected with one end of the first resistor, and the other end of the first resistor is connected with the output end of the constant current source.
3. The temperature measurement circuit of three-wire thermal resistor according to claim 1, further comprising:
the second resistor is connected between the first voltage acquisition end and one end of the first lead; and the number of the first and second groups,
and one end of the first capacitor is connected with the first voltage acquisition end, and the other end of the first capacitor is connected with a power ground.
4. The temperature measurement circuit of three-wire thermal resistor according to claim 1, further comprising:
a third resistor connected between the second voltage acquisition end and one end of the second wire; and the number of the first and second groups,
and the second capacitor is connected with the second voltage acquisition end at one end and connected with a power ground at the other end.
5. The three-wire system thermal resistance temperature measurement circuit according to claim 1, further comprising:
and one end of the third capacitor is connected with the first voltage acquisition end, and the other end of the third capacitor is connected with the second voltage acquisition end.
6. The three-wire system thermal resistance temperature measurement circuit according to claim 1, further comprising:
and the fourth resistor is connected between the third voltage acquisition end and one end of the third lead.
7. The three-wire system thermal resistance temperature measurement circuit according to claim 1, further comprising:
the fifth resistor is connected between the reference voltage input end and the other end of the precision resistor; and the number of the first and second groups,
and one end of the fourth capacitor is connected with the reference voltage input end, and the other end of the fourth capacitor is connected with a power ground.
8. The three-wire system thermal resistance temperature measurement circuit according to claim 1, further comprising:
and the fifth capacitor is connected with the precision resistor in parallel.
9. The three-wire system thermal resistance temperature measurement circuit according to claim 1, further comprising:
a transient suppression diode in parallel with the precision resistor.
10. The three-wire thermal resistor temperature measurement circuit according to any one of claims 1 to 9, wherein the MCU and the analog-to-digital converter are connected via an SPI bus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922392530.6U CN211347137U (en) | 2019-12-26 | 2019-12-26 | Temperature measuring circuit of three-wire thermal resistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922392530.6U CN211347137U (en) | 2019-12-26 | 2019-12-26 | Temperature measuring circuit of three-wire thermal resistor |
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| Publication Number | Publication Date |
|---|---|
| CN211347137U true CN211347137U (en) | 2020-08-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922392530.6U Active CN211347137U (en) | 2019-12-26 | 2019-12-26 | Temperature measuring circuit of three-wire thermal resistor |
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| CN (1) | CN211347137U (en) |
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Effective date of registration: 20210401 Address after: 100176 Floor 5 510-1515, No. 1 Building, No. 2 Courtyard, Dishengzhong Road, Daxing District Economic and Technological Development Zone, Beijing Patentee after: BEIJING HOLLYSYS AUTOMATION & DRIVE Co.,Ltd. Address before: 100176 1510-1515, floor 5, building 1, yard 2, Disheng Middle Road, Beijing Economic and Technological Development Zone, Beijing Patentee before: BEIJING HOLLYSYS AUTOMATION & DRIVE Co.,Ltd. Patentee before: NINGBO HELISHI INTELLIGENT TECHNOLOGY Co.,Ltd. |
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