CN212988630U - Temperature acquisition circuit, control panel and electrical equipment - Google Patents
Temperature acquisition circuit, control panel and electrical equipment Download PDFInfo
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- CN212988630U CN212988630U CN202021834186.8U CN202021834186U CN212988630U CN 212988630 U CN212988630 U CN 212988630U CN 202021834186 U CN202021834186 U CN 202021834186U CN 212988630 U CN212988630 U CN 212988630U
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- operational amplifier
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- thermistor
- temperature acquisition
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Abstract
The utility model is suitable for the technical field of temperature acquisition, in particular to a temperature acquisition circuit, a control panel and electrical equipment, wherein the temperature acquisition circuit comprises an operational amplifier; a reference unit for providing a reference voltage to the operational amplifier; a comparison unit for providing a comparison voltage to the operational amplifier; the feedback unit is used for providing a negative feedback signal to the operational amplifier so as to realize the amplification of the voltage difference between the reference voltage and the comparison voltage, and comprises a thermistor, wherein one end of the thermistor, which comprises two lines, is connected with the inverting input end of the operational amplifier, and one end of the thermistor, which comprises one line, is connected with the output end of the operational amplifier; in the voltage acquisition unit, a first voltage acquisition module is connected with one end of the thermistor, which comprises two lines, and a second voltage acquisition module is connected with the output end of the operational amplifier. The utility model discloses need not to increase fortune and put to do impedance conversion and use too much component, can realize temperature acquisition, the effectual precision that improves temperature acquisition.
Description
Technical Field
The utility model belongs to the technical field of the temperature acquisition, especially, relate to a temperature acquisition circuit, control panel and electrical equipment.
Background
The wheatstone bridge (also called single-arm bridge) is an instrument capable of accurately measuring the resistance, and in the general wheatstone bridge, the resistances R1, R2, R3 and R4 are four arms of the bridge, and the branch where the bridge is located can be checked for current by a galvanometer. When the galvanometer has no current through it, it is called a bridge to reach equilibrium. In balance, the resistances of the four bridge arms satisfy a simple relationship, and the resistance can be measured by utilizing the relationship.
A wheatstone bridge in the prior art is shown in fig. 1, wherein R2 represents a PT100 platinum electrode, and when the platinum electrode collects temperature, the accuracy is affected by the accuracy of the resistors used, such as those of R1, R3, R4, R5, R6, R7, and R8, so that two operational amplifiers are required to be added for impedance conversion, and then differential amplification output detection is performed, in the circuit, it is required that R1 is equal to R4, and currently, only when R2 is equal to R3, the effect caused by internal resistance is completely cancelled, and when R2 changes, the circuit balance of the wheatstone bridge is broken, and the voltage division state on the internal resistance changes accordingly (Vr1 is equal to Vr3), so the effect caused by line resistance cannot be completely cancelled. However, the addition of an operational amplifier for impedance conversion greatly increases the circuit cost, and the precision of each resistor is different due to the use of a plurality of resistors, so that the wheatstone bridge is difficult to balance.
SUMMERY OF THE UTILITY MODEL
The utility model provides a temperature acquisition circuit solves and needs to increase operational amplifier and do impedance conversion and use too much component, just can realize the problem of temperature acquisition.
The utility model discloses a realize like this, a temperature acquisition circuit, include:
an operational amplifier;
a reference unit for providing a reference voltage to the operational amplifier;
a comparison unit for providing a comparison voltage to the operational amplifier;
the feedback unit is used for providing a negative feedback signal to the operational amplifier so as to realize the amplification of the voltage difference between the reference voltage and the comparison voltage, and comprises a thermistor, wherein one end of the thermistor, which comprises two lines, is connected with the inverting input end of the operational amplifier, and one end of the thermistor, which comprises one line, is connected with the output end of the operational amplifier;
and the voltage acquisition unit comprises a first voltage acquisition module and a second voltage acquisition module, the first voltage acquisition module is connected with one end of the thermistor containing two lines, and the second voltage acquisition module is connected with the output end of the operational amplifier.
Furthermore, the temperature acquisition circuit further comprises a filter capacitor, one end of the filter capacitor is connected with the inverting input end of the operational amplifier, and the other end of the filter capacitor is connected with the output end of the operational amplifier.
Furthermore, the comparison unit comprises a comparison resistor, and the comparison resistor is connected with the inverting input end of the operational amplifier.
Furthermore, the reference unit includes a first resistor, a second resistor, and a diode, one end of the first resistor is connected to one end of the second resistor and a negative electrode of the diode, the other end of the first resistor is connected to a power source terminal, the other end of the second resistor is connected to a positive input terminal of the operational amplifier, and a positive electrode of the diode is connected to a ground terminal.
Furthermore, the reference unit includes a third resistor and a reference voltage chip, the reference voltage chip is respectively connected to one end of the third resistor, the positive phase input terminal of the operational amplifier and the ground terminal, and the other end of the third resistor is connected to a power supply terminal.
Further, the thermistor has a positive temperature coefficient.
The utility model also provides a control panel, include the temperature acquisition circuit.
The utility model also provides an electrical equipment, include the control panel.
The beneficial effects of the utility model reside in that, this temperature acquisition circuit only through an operational amplifier with use a thermistor, can accomplish temperature acquisition, need not to use too much device, has eliminated the line resistance to the influence of gathering the precision, the effectual precision that has improved temperature detection obtains accurate temperature value.
Drawings
FIG. 1 is a schematic diagram of a prior art Wheatstone bridge circuit;
fig. 2 is a block diagram of a temperature acquisition circuit provided in the first embodiment of the present invention;
fig. 3 is a schematic diagram of a temperature acquisition circuit provided in the first embodiment of the present invention;
fig. 4 is an example of a first voltage acquisition module and a second voltage acquisition module provided in the first embodiment of the present invention;
fig. 5 is a schematic diagram of a thermistor according to an embodiment of the present invention, in which (a) is a three-wire thermistor circuit diagram and (b) is an equivalent diagram of the three-wire thermistor;
fig. 6 is a circuit diagram of a reference unit according to a fourth embodiment of the present invention;
fig. 7 is a circuit diagram of a reference unit according to a fifth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the utility model provides a temperature acquisition circuit, when thermistor Rpt gathers the temperature, thermistor Rpt provides negative feedback signal to operational amplifier 1, and simultaneously, comparison unit 3 provides comparison voltage for operational amplifier 1, thereby realize the enlargements of reference voltage and comparison voltage's pressure differential through operational amplifier 1, first voltage acquisition module and second voltage acquisition module gather the voltage that thermistor Rpt contains the one end of two lines respectively, and the voltage of operational amplifier 1's output, reunion reference unit 2 provides reference voltage for operational amplifier 1, can obtain thermistor Rpt's resistance, and then obtain the temperature that thermistor Rpt's resistance corresponds, accomplish temperature acquisition. The temperature acquisition circuit can finish temperature acquisition only by one operational amplifier 1 and one thermistor Rpt without using too many devices, eliminates the influence of wire resistance on acquisition precision, effectively improves the precision of temperature detection and obtains an accurate temperature value.
Example one
Referring to fig. 2 and 3, the present embodiment provides a temperature acquisition circuit including:
an operational amplifier 1;
a reference unit 2 that supplies a reference voltage Verf to the operational amplifier 1;
a comparison unit 3 for supplying a comparison voltage to the operational amplifier 1;
the feedback unit 4 is used for providing a negative feedback signal to the operational amplifier 1 so as to realize the differential pressure amplification of the reference voltage Verf and the comparison voltage, and comprises a thermistor Rpt, wherein one end of the thermistor Rpt, which comprises two lines, is connected with the inverting input end of the operational amplifier 1, and one end of the thermistor Rpt, which comprises one line, is connected with the output end of the operational amplifier 1;
and the voltage acquisition unit 5 comprises a first voltage acquisition module and a second voltage acquisition module, the first voltage acquisition module is connected with one end of the thermistor Rpt, which contains two lines, and the second voltage acquisition module is connected with the output end of the operational amplifier 1.
The model of the operational amplifier is preferably TLV314IDBVR, and the thermistor is preferably PT 100. The first voltage acquisition module and the second voltage acquisition module may be AD acquisition ports on the single chip microcomputer, or independent AD acquisition chips, as shown in fig. 4, which is not limited herein.
Specifically, as shown in fig. 5(a), the thermistor Rpt100 has a three-wire platinum electrode structure including one resistor r1 at one end and two resistors r2 and r3 at the other end, and the lead wire of each resistor is made of a material with equal length and equal wire diameter, so that the three resistors are equal by default, that is, r 1-r 2-r 3-r, and the thermistor Rpt100 can be equivalent to a three-wire platinum electrode structure including one wire (PT100-1) at one end and two wires (PT100-2 and PT100-3) at the other end, and the temperature acquisition circuit in this embodiment is equivalent to a circuit shown in fig. 5 (b).
The working principle of the temperature acquisition circuit is as follows:
when the thermistor collects temperature, the thermistor Rpt provides a negative feedback signal to the operational amplifier 1, meanwhile, the comparison unit 3 provides a comparison voltage for the operational amplifier 1, so that the amplification of the voltage difference between the reference voltage Verf and the comparison voltage is realized through the operational amplifier 1, the first voltage collection module and the second voltage collection module respectively collect the voltage Vad1 at one end of the thermistor Rpt including two lines and the voltage Vad2 at the output end of the operational amplifier 1, and then the reference unit 2 is combined to provide the reference voltage Verf for the operational amplifier 1, so that the resistance value of the thermistor Rpt100 can be obtained, and further the temperature corresponding to the resistance value of the thermistor Rpt100 is obtained, and the temperature collection is completed.
In the embodiment, the temperature acquisition can be completed only by one operational amplifier and one thermistor without using excessive devices (such as resistors), so that the influence of the wire resistance on the acquisition precision is eliminated, the precision of temperature detection is effectively improved, and an accurate temperature value is obtained.
Example two
As shown in fig. 3, based on the first embodiment, the temperature acquisition circuit further includes a filter capacitor C1, one end of the filter capacitor C1 is connected to the inverting input terminal of the operational amplifier 1, and the other end of the filter capacitor C1 is connected to the output terminal of the operational amplifier 1.
Specifically, the filter capacitor C1 is connected between the inverting input terminal and the output terminal of the operational amplifier 1, and is connected in parallel with the thermistor Rpt 100.
In this embodiment, the voltage signal in the circuit is filtered through the filter capacitor C1, so that the output voltage of the operational amplifier 1 is more stable, the data is more accurate, and a more accurate temperature value is obtained.
EXAMPLE III
In the present embodiment, on the basis of the first embodiment, the comparing unit 3 includes a comparing resistor R1, and the comparing resistor R1 is connected to the inverting input terminal of the operational amplifier 1.
Specifically, one end of the comparison resistor R1 is connected to the inverting input terminal of the operational amplifier 1, the other end is grounded, and the thermistor Rpt100 includes one end of a line (PT100-1) and one end of the filter capacitor C1, which are further connected to a connection line between the comparison resistor R1 and the inverting input terminal of the operational amplifier 1.
Referring to fig. 5, in the present embodiment, a specific relationship exists between the voltage Vad2 at the output end of the operational amplifier and the resistance value of the thermistor Rpt100, that is, Rpt100 is (Vad2-2Vad1+ Verf) × R1/Verf), the resistance value of the thermistor Rpt100 can be obtained by using Vad1 and Vad2 collected by the voltage collecting unit 5, the known reference voltage Vref and the comparison resistor R1, and there is no wire resistor R factor in the calculation of the resistance value of the thermistor Rpt100, so that the influence of the wire resistor on the collecting accuracy can be eliminated in the temperature collecting process of the present embodiment, and the obtained temperature value is more accurate.
In this embodiment, the comparison resistor R1 is connected to the inverting input terminal of the operational amplifier 1 to provide a comparison voltage for the operational amplifier 1, so that the feedback unit 4 amplifies the voltage difference between the reference voltage Verf and the comparison voltage, thereby ensuring the stability of the gain and the output signal and accurately acquiring the temperature information.
Example four
In the present embodiment, on the basis of the first embodiment, as shown in fig. 6, the reference unit 2 includes a first resistor R21, a second resistor R22, and a diode D1, one end of the first resistor R21 is connected to one end of the second resistor R22 and the negative electrode of the diode D1, the other end of the first resistor R21 is connected to the power supply terminal VDD (3V3), the other end of the second resistor R22 is connected to the non-inverting input terminal of the operational amplifier 1, and the positive electrode of the diode D1 is connected to the ground terminal.
Specifically, the diode D1 is preferably of the type AD 1580. The first resistor R21 and the diode D1 connected in series constitute a reference cell structure, and provide a reference voltage Vref to the operational amplifier 1, and the second resistor R22 performs current limiting protection in a line where the reference voltage Vref is input to the operational amplifier 1.
In this embodiment, the reference voltage Vref used for calculating the resistance of the thermistor Rpt100 is provided for the operational amplifier by the first resistor R21 and the diode D1 which are connected in series, and the second resistor R22 is used as a protection resistor to protect the circuit, so that the operational amplifier and other devices are prevented from being burnt by excessive current.
EXAMPLE five
In the first embodiment, as shown in fig. 7, the reference unit 2 includes a third resistor R23 and a reference voltage chip U1, the reference voltage chip U1 is respectively connected to one end of the third resistor R23, the non-inverting input terminal and the ground terminal of the operational amplifier 1, and the other end of the third resistor R23 is connected to a power supply terminal VDD (3V 3).
Specifically, the reference voltage chip U1 is preferably of model TL431, and the reference voltage chip U1 is connected in series with a third resistor R23 to provide the reference voltage Vref for the operational amplifier.
In the embodiment, the operational amplifier is provided with the reference voltage Vref through the third resistor R23 and the reference voltage chip U1 which are connected in series, and the reference voltage Vref is used for calculating the resistance value of the thermistor Rpt 100.
EXAMPLE six
In the present embodiment, a temperature acquisition circuit is provided, and based on the first embodiment, the thermistor Rpt100 has a positive temperature coefficient.
Specifically, the thermistor Rpt100 has a positive temperature coefficient, has temperature sensitivity, and can be used as a temperature sensor, and when a current passes through the thermistor Rpt100, a temperature rise is caused, that is, a temperature rise of a heating body, and when a curie point temperature is exceeded, a resistance value increases stepwise with the temperature rise, and the higher the temperature, the larger the resistance value.
In the embodiment, the thermistor Rpt100 with a positive temperature coefficient is adopted, and the ptc effect can be generated after the current passes through the thermistor Rpt100, so that the accurate detection of the temperature is realized, and the thermistor has good stability and strong overload capacity.
EXAMPLE seven
The present embodiment provides a control board, including the temperature acquisition circuit of any one of the first to sixth embodiments.
In this embodiment, the control panel has eliminated the influence of line resistance to gathering the precision owing to adopted the temperature acquisition circuit in the aforesaid embodiment, the effectual precision that improves temperature detection for the control panel can realize accurate ground temperature collection.
Example eight
The present embodiment provides an electrical apparatus comprising the control board of embodiment seven.
In particular, the electrical device may be, but is not limited to, a temperature monitor.
In this embodiment, because the control panel in the foregoing embodiment is adopted, accurate temperature acquisition can be realized, so that the electrical equipment can timely and accurately acquire the ambient temperature information.
To sum up, the embodiment of the utility model provides a temperature acquisition circuit only through an operational amplifier with use a thermistor, can accomplish temperature acquisition, need not to use too much device, has eliminated the influence of line resistance to gathering the precision, the effectual precision that has improved temperature detection obtains accurate temperature value. Furthermore, voltage signals in the circuit are filtered through the filter capacitor, the output voltage of the operational amplifier is more stable, data are more accurate, and then a more accurate temperature value is obtained. Preferably, the operational amplifier is provided with a reference voltage for resistance calculation of the thermistor through a first resistor, a diode, or a third resistor and a reference voltage chip which are connected in series. By adopting the thermistor with positive temperature coefficient, the ptc effect can be generated after the current passes through the thermistor, the accurate detection of the temperature is realized, the stability is good, and the overload capacity is strong. The embodiment of the utility model provides a control panel is still provided, because it has adopted this temperature acquisition circuit, eliminated the line and hindered the influence to gathering the precision, the effectual precision that improves temperature detection for the control panel can realize accurate ground temperature collection. The embodiment of the utility model provides an electrical equipment still provides, owing to adopted this control panel, can realize accurate ground temperature acquisition for electrical equipment acquires ambient temperature information in time accurately.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A temperature acquisition circuit, comprising:
an operational amplifier;
a reference unit for providing a reference voltage to the operational amplifier;
a comparison unit for providing a comparison voltage to the operational amplifier;
the feedback unit is used for providing a negative feedback signal to the operational amplifier so as to realize the amplification of the voltage difference between the reference voltage and the comparison voltage, and comprises a thermistor, wherein one end of the thermistor, which comprises two lines, is connected with the inverting input end of the operational amplifier, and one end of the thermistor, which comprises one line, is connected with the output end of the operational amplifier;
and the voltage acquisition unit comprises a first voltage acquisition module and a second voltage acquisition module, the first voltage acquisition module is connected with one end of the thermistor containing two lines, and the second voltage acquisition module is connected with the output end of the operational amplifier.
2. The temperature acquisition circuit of claim 1, further comprising a filter capacitor, wherein one end of the filter capacitor is connected to the inverting input terminal of the operational amplifier, and the other end of the filter capacitor is connected to the output terminal of the operational amplifier.
3. The temperature acquisition circuit of claim 1, wherein the comparison unit comprises a comparison resistor connected to the inverting input of the operational amplifier.
4. The temperature acquisition circuit according to claim 1, wherein the reference unit comprises a first resistor, a second resistor and a diode, one end of the first resistor is connected to one end of the second resistor and the cathode of the diode respectively, the other end of the first resistor is connected to a power supply terminal, the other end of the second resistor is connected to a non-inverting input terminal of the operational amplifier, and the anode of the diode is connected to a ground terminal.
5. The temperature acquisition circuit according to claim 1, wherein the reference unit comprises a third resistor and a reference voltage chip, the reference voltage chip is respectively connected to one end of the third resistor, the positive input end of the operational amplifier and the ground end, and the other end of the third resistor is connected to a power supply end.
6. The temperature acquisition circuit of claim 1, wherein the thermistor has a positive temperature coefficient.
7. A control board comprising a temperature acquisition circuit as claimed in any one of claims 1 to 6.
8. An electrical appliance comprising the control board of claim 7.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021834186.8U CN212988630U (en) | 2020-08-27 | 2020-08-27 | Temperature acquisition circuit, control panel and electrical equipment |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021834186.8U CN212988630U (en) | 2020-08-27 | 2020-08-27 | Temperature acquisition circuit, control panel and electrical equipment |
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| CN212988630U true CN212988630U (en) | 2021-04-16 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116170019A (en) * | 2023-01-06 | 2023-05-26 | 深圳市西京电力科技有限公司 | High-power electronic device based on semiconductor thermistor |
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- 2020-08-27 CN CN202021834186.8U patent/CN212988630U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116170019A (en) * | 2023-01-06 | 2023-05-26 | 深圳市西京电力科技有限公司 | High-power electronic device based on semiconductor thermistor |
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