CN210833909U - Temperature measurement circuit and cooking utensil - Google Patents
Temperature measurement circuit and cooking utensil Download PDFInfo
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- CN210833909U CN210833909U CN201921619022.0U CN201921619022U CN210833909U CN 210833909 U CN210833909 U CN 210833909U CN 201921619022 U CN201921619022 U CN 201921619022U CN 210833909 U CN210833909 U CN 210833909U
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- 238000010411 cooking Methods 0.000 title claims abstract description 11
- 238000009529 body temperature measurement Methods 0.000 title abstract description 31
- 230000003321 amplification Effects 0.000 claims abstract description 61
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 61
- 239000003990 capacitor Substances 0.000 claims description 48
- 238000004861 thermometry Methods 0.000 claims description 5
- 238000012545 processing Methods 0.000 claims description 4
- 230000006698 induction Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 8
- 230000005672 electromagnetic field Effects 0.000 description 5
- 238000001914 filtration Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 2
- 229910001120 nichrome Inorganic materials 0.000 description 2
- PEUPIGGLJVUNEU-UHFFFAOYSA-N nickel silicon Chemical compound [Si].[Ni] PEUPIGGLJVUNEU-UHFFFAOYSA-N 0.000 description 2
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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Abstract
The utility model provides a temperature measurement circuit and cooking utensil, this temperature measurement circuit includes: the thermocouple device comprises a thermocouple (10), an inverting input circuit (11), a non-inverting input circuit (12), a power supply circuit (13), an operational amplification circuit (14) and a micro control unit (15), wherein a first end of the inverting input circuit (11) is connected with the thermocouple (10), a second end of the inverting input circuit (11) is connected with an inverting input end of the operational amplification circuit (14), and the non-inverting input circuit (12) is connected with a non-inverting input end of the operational amplification circuit (14); the output end of the operational amplification circuit (14) is connected with the micro control unit (15), and the operational amplification circuit (14) is also connected with the power circuit (13). The utility model discloses a reverse phase input circuit enlargies the thermoelectromotive force signal of thermocouple output, has reduced the amplification performance requirement to operational amplification circuit to the higher problem of temperature measurement circuit cost has been solved.
Description
Technical Field
The utility model relates to a household electrical appliances technical field especially relates to a temperature measurement circuit and cooking utensil.
Background
An induction cooker is a common household appliance for heating. When the induction cooker works, high-frequency alternating current passes through the coil panel to enable the bottom of a pot placed on the induction cooker to generate eddy current, so that the pot arranged on the induction cooker is heated. In the working process of the induction cooker, accurate temperature control is often required, so that a temperature measuring circuit is required to be arranged on the induction cooker.
In the prior art, in order to accurately monitor the temperature of the induction cooker, the temperature is measured by the thermocouple, and because the electromagnetic field generated by the coil panel of the induction cooker generates interference to the thermal electromotive force signal output by the thermocouple, the interference appears as a common-mode interference signal, and at present, the interference problem is usually solved by two modes: firstly, the problem is solved by a thermocouple with a metal shield; and secondly, processing the common-mode interference signal by adopting a circuit formed by combining an operational amplifier with a high common-mode rejection ratio or a plurality of operational amplifiers.
Then, the performance requirement of the elements required by the temperature measuring circuit in the prior art is higher, and the number of the elements is larger, so that the cost is higher.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a temperature measurement circuit and cooking utensil to it is higher to overcome the required component performance requirement of temperature measurement circuit, the higher problem of temperature measurement circuit cost.
In a first aspect, the utility model provides a temperature measurement circuit, include: the device comprises a thermocouple, an inverse phase input circuit, an in-phase input circuit, a power supply circuit, an operational amplification circuit and a micro control unit;
the first end of the reverse-phase input circuit is connected with the thermocouple, the second end of the reverse-phase input circuit is connected with the reverse-phase input end of the operational amplification circuit, and the in-phase input circuit is connected with the in-phase input end of the operational amplification circuit;
the thermocouple is used for acquiring temperature information and converting the temperature information into a thermoelectromotive force signal; the inverting input circuit is used for amplifying the thermal electromotive force signal to obtain a first input signal and transmitting the first input signal to the inverting input end of the operational amplification circuit; the non-inverting input circuit is used for inputting a second input signal to a non-inverting input end of the operational amplification circuit;
the output end of the operational amplification circuit is connected with the micro control unit, the operational amplification circuit is also connected with the power supply circuit, the power supply circuit is used for providing working voltage for the operational amplification circuit, and the operational amplification circuit is used for carrying out amplification processing according to the first input signal and the second input signal;
the micro control unit is used for acquiring the temperature information according to the electric signal output by the operational amplification circuit.
In the temperature measuring circuit provided by the utility model, the thermocouple is used for collecting temperature information and converting the temperature information into a thermoelectromotive force signal, and the accuracy of the temperature information collected by the thermocouple is higher; in addition, the thermal electromotive force signal output by the thermocouple is amplified through the inverting input circuit, so that the inverting input end input to the operational amplification circuit has higher input voltage, the requirement on the amplification performance of the operational amplification circuit is reduced, and the cost of the temperature measurement circuit is reduced.
In one possible implementation, an inverting input circuit includes: a resistor R3 and a capacitor C3;
the positive output end of the thermocouple is grounded through a first thermocouple wire, the negative output end of the thermocouple is connected to the first end of the resistor R3 through a second thermocouple wire, the second end of the resistor R3 is respectively connected with the inverting input end of the operational amplifier circuit and the first end of the capacitor C3, and the second end of the capacitor C3 is grounded.
The utility model provides a temperature measurement circuit through set up resistance R3 between the output of thermocouple and operational amplification circuit, and resistance R3's resistance value is higher to improve circuit's input resistance, make operational amplification circuit's inverting input have higher input voltage, thereby reduced the amplification performance requirement to operational amplification circuit, reduced temperature measurement circuit's cost.
In one possible implementation, the first thermocouple wire and the second thermocouple wire are intertwined.
In this possible implementation manner, the first thermocouple wire and the second thermocouple wire are wound with each other, so that the interference of the electromagnetic field generated by the coil panel of the induction cooker on the thermoelectromotive force signal can be reduced, and the accuracy of the temperature information acquired by the micro control unit is improved.
In one possible implementation manner, the temperature measuring circuit further includes: a common mode inductor;
the first thermocouple wire is grounded through the common mode inductor, and the second thermocouple wire is connected to the first end of the resistor R3 through the common mode inductor.
In the possible implementation mode, the common-mode inductor is arranged between the output end of the thermocouple and the inverted input resistor and can filter common-mode electromagnetic interference signals, so that the interference of an electromagnetic field generated by a coil panel of the induction cooker on thermal electromotive force signals can be reduced, and the accuracy of temperature information acquired by the micro control unit is improved.
In one possible implementation, the operational amplifier circuit includes an operational amplifier and a feedback network circuit, wherein the feedback network circuit includes a resistor R1 and a capacitor C1;
the inverting input end of the operational amplifier is respectively connected with the second end of the inverting input circuit, the first end of the resistor R1 and the first end of the capacitor C1;
the non-inverting input end of the operational amplifier is connected with the non-inverting input circuit;
the output end of the operational amplifier is respectively connected with the second end of the resistor R1 and the second end of the capacitor C1.
The utility model provides a temperature measurement circuit, through the magnification of resistance R2 control operational amplification circuit, simple and convenient, and the cost is lower, in addition, electric capacity C1 can compensate the influence that operational amplifier phase lag and parasitic capacitance produced, and electric capacity C1 can also eliminate the self-oscillation that the circuit produced.
In one possible implementation manner, the non-inverting input circuit includes a resistor R4, a first end of the resistor R4 is grounded, and a second end of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier.
The utility model provides a temperature measurement circuit provides the second input signal that voltage is zero through cophase input circuit to operational amplification circuit's cophase input end to the characteristic through operational amplifier itself makes operational amplifier's inverting input end and cophase input end's voltage equal, therefore, this operational amplifier does not have common mode signal input, that is to say, the utility model provides a temperature measurement circuit itself has higher common mode rejection ratio, and then does not have common mode rejection ratio requirement to operational amplifier to reduce temperature measurement circuit cost.
In one possible implementation manner, the temperature measuring circuit further includes: an output circuit;
the first end of the output circuit is connected with the output end of the operational amplification circuit, and the second end of the output circuit is connected with the micro control unit.
In a possible implementation manner, the output circuit includes a capacitor C2 and a resistor R2, an output terminal of the operational amplifier circuit is connected to a first terminal of the resistor R2 and a first terminal of the capacitor C2, a second terminal of the resistor R2 is connected to the micro control unit, and a second terminal of the capacitor C2 is grounded.
The utility model provides a temperature measurement circuit, through the electric capacity C2 filtering operational amplification circuit's among the output circuit high frequency noise, improve the accuracy of the temperature information that little the control unit acquireed; in addition, the current input to the micro control unit is limited through the resistor R2 in the output circuit, so that the micro control unit is prevented from being damaged due to the fact that the current is too large, and the reliability of the temperature measuring circuit is improved.
In one possible implementation, the power supply circuit includes: a resistor R5 and a capacitor C5;
the first end of the resistor R5 is connected with the operational amplifier circuit and the first end of the capacitor C5, the second end of the capacitor C5 is grounded, and the second end of the resistor R5 is connected with a power supply.
The utility model provides a temperature measurement circuit, power supply circuit are used for providing operating voltage to operational amplification circuit, and power supply provides operating voltage to operational amplification circuit through resistance R5, and resistance R5 can reduce the noise among the power supply to operational amplification circuit's influence, in addition, electric capacity C5 among the power supply circuit can the filtering power supply output the interference signal in the signal of telecommunication.
In one possible implementation, the resistance R3 is equal to the resistance of the resistor R4, and/or the resistance of the resistor R3 is greater than or equal to 10K ohms.
The utility model provides a temperature measurement circuit, the resistance value size through with resistance R4 sets up to be the same with resistance R3's resistance value size to the symmetry of compensation operational amplification circuit in-phase input end and inverting input end.
In a second aspect, the present invention provides a cooking appliance comprising a thermometry circuit as described above in the first aspect or in various possible designs of the first aspect.
The structure of the present invention and other objects and advantages thereof will be more clearly understood from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.
Drawings
Fig. 1 is a schematic structural diagram of a temperature measuring circuit according to the present invention;
fig. 2 is a schematic structural diagram of a temperature measuring circuit according to the present invention;
fig. 3 is a schematic structural diagram of a temperature measuring circuit provided by the present invention;
fig. 4 is a schematic structural diagram of the temperature measuring circuit provided by the present invention.
Description of reference numerals:
10-a thermocouple;
11-an inverting input circuit;
12-a non-inverting input circuit;
13-a power supply circuit;
14-an operational amplifier circuit;
15-a micro control unit;
16-a first thermocouple wire;
17-a second thermocouple wire;
18-an operational amplifier;
19-a feedback network circuit;
20-an output circuit;
l1-common mode inductance.
Detailed Description
Fig. 1 is a schematic structural diagram of a temperature measuring circuit according to the present invention; fig. 2 is a schematic structural diagram of a temperature measuring circuit according to the present invention; fig. 3 is a schematic structural diagram of a temperature measuring circuit according to the present invention.
Referring to fig. 1, the temperature measuring circuit provided in this embodiment includes: thermocouple 10, inverting input circuit 11, non-inverting input circuit 12, power supply circuit 13, operational amplifier circuit 14, and micro control unit 15.
The first end of the inverting input circuit 11 is connected to the thermocouple 10, the second end of the inverting input circuit 11 is connected to the inverting input terminal of the operational amplifier circuit 14, and the non-inverting input circuit 12 is connected to the non-inverting input terminal of the operational amplifier circuit 14.
The output end of the operational amplifier circuit 14 is connected with the micro control unit 15, and the operational amplifier circuit 14 is also connected with the power supply circuit 13.
The thermocouple 10 is used for collecting temperature information and converting the temperature information into a thermoelectromotive force signal; the inverting input circuit 11 is configured to amplify the thermal electromotive force signal to obtain a first input signal, and transmit the first input signal to an inverting input terminal of the operational amplifier circuit 14; the non-inverting input circuit 12 is configured to input a second input signal to a non-inverting input terminal of the operational amplifier circuit 14.
The thermocouple 10 has the characteristics of simple structure, wide measurement range, high precision, small inertia, convenience in remote transmission of output signals and the like, the thermocouple 10 is more convenient to acquire temperature information, and the temperature information acquired by the thermocouple is more accurate.
Illustratively, the thermocouple 10 may be a type K thermocouple. The thermocouple 10 may also be referred to as a thermocouple temperature sensor, a thermocouple sensor, or other names, and the present invention is not limited to the specific model and name of the thermocouple 10.
Since the thermal electromotive force signal output by the thermocouple 10 is usually weak, in the embodiment of the present invention, the thermal electromotive force signal is amplified by the inverting input circuit 11, so that the first input signal input to the inverting input terminal of the operational amplifier circuit 14 has a higher voltage.
In this embodiment, the inverting input circuit 11 can amplify the thermal electromotive force signal, and this inverting input circuit 11 can be a circuit including a resistor and a capacitor, and this embodiment does not make any particular limitation to the specific implementation manner of the inverting input circuit 11, and all circuits that can amplify the thermal electromotive force signal belong to the protection category of the present invention.
In this embodiment, the operational amplifier circuit 14 is mainly configured to perform amplification processing according to the first input signal and the second input signal, and output an electrical signal to the micro control unit 15, and the micro control unit 15 is configured to obtain temperature information according to the electrical signal output by the operational amplifier circuit 14.
Illustratively, the MCU 15 may be an MCU, and the MCU 15 may also be called a single chip microcomputer (single chip microcomputer) or a single chip Microcomputer (MCU). The micro-control unit 15 may include an analog-to-digital (AD) interface, i.e. the AD shown in fig. 2, where the AD indicates that an analog signal is converted into a digital signal, and the output terminal of the operational amplifier circuit 14 is connected to the AD interface of the micro-control unit 15.
In a possible implementation, the micro control unit 15 obtains the temperature information according to the voltage of the electrical signal output by the operational amplifier circuit 14. If the output end of the operational amplifier circuit 14 is connected to the AD interface of the micro control unit 15, the micro control unit 15 may obtain the temperature information according to the voltage of the electrical signal on the AD interface.
It should be noted that, in practical application, the micro control unit is further connected to a power supply, as shown in fig. 2, the micro control unit is connected to a VCC, and the VCC provides a working voltage to the micro control unit, so as to ensure normal operation of the micro control unit. In addition, the micro control unit can also comprise a grounding point.
The power supply circuit 13 is mainly used to supply an operating voltage to the operational amplifier circuit 14. It should be noted that, in some embodiments, the power circuit 13 may not be shown, which also belongs to the protection scope of the present invention.
The working process of the temperature measuring circuit provided by the embodiment mainly comprises the following steps: the thermocouple 10 collects temperature information and converts the temperature information into a thermal electromotive force signal, the reverse phase input circuit 11 amplifies the thermal electromotive force signal to obtain a first input signal, the first input signal is input to the reverse phase input end of the operational amplification circuit 14, the in-phase input circuit 12 inputs a second input signal to the in-phase input end of the operational amplification circuit 14, the operational amplification circuit 14 amplifies the first input signal and the second input signal, the operational amplification circuit 14 outputs an electric signal to the micro control unit 15 through the output end, and the micro control unit 15 obtains the temperature information according to the electric signal output by the operational amplification circuit 14.
The temperature measurement circuit provided by the embodiment amplifies the thermal electromotive force signal output by the thermocouple 10 through the inverting input circuit 11, so that the inverting input end of the operational amplifier circuit 14 has higher input voltage, the requirement on the amplification performance of the operational amplifier circuit 14 is reduced through the above manner, and the temperature measurement circuit can be realized by adopting the common operational amplifier circuit 14 in practical application, so that the cost of the temperature measurement circuit is reduced.
With reference to fig. 1, fig. 2 and fig. 3, in a possible implementation manner, the inverting input circuit 11 includes a resistor R3 and a capacitor C3, wherein the positive output terminal of the thermocouple 10 is grounded through a first thermocouple 10 line, the negative output terminal of the thermocouple 10 is connected to a first end of the resistor R3 through a second thermocouple 10 line, a second end of the resistor R3 is connected to the inverting input terminal of the operational amplifier circuit 14 and a first end of the capacitor C3, and a second end of the capacitor C3 is grounded.
Wherein, the positive output end of the thermocouple is shown as "+" in the thermocouple shown in fig. 2 and 3, and the negative output end of the thermocouple is shown as "-" in the thermocouple shown in fig. 2 and 3.
Optionally, the resistance value of the resistor R3 is greater than 10K ohms.
The utility model discloses a set up resistance R3 between thermocouple 10's output and operational amplification circuit 14, and resistance R3's resistance value is higher to improve circuit's input resistance, make operational amplification circuit 14's inverting input have higher input voltage, thereby reduced the amplification performance requirement to operational amplification circuit 14, reduced temperature measurement circuit's cost.
In addition, the capacitor C3 in the inverting input circuit 14 can effectively filter the glitch interference signal output by the thermocouple, and transmit the effective signal containing the temperature information to the operational amplifier circuit, so that the operational amplifier circuit amplifies the effective signal.
Alternatively, as shown in fig. 2, the first thermocouple 10 wire and the second thermocouple 10 wire are wound around each other.
The first thermocouple 10 line and the second thermocouple 10 line may be cables composed of nichrome lines and an insulating layer, wherein the insulating layer is located outside the nichrome lines.
The first and second thermocouple 10 wires may also be cables composed of nickel-silicon wires and an insulating layer, wherein the insulating layer is located at the outer side of the nickel-silicon wires.
Alternatively, the insulating layer may be made of glass fiber.
In this embodiment, the first thermocouple wire 16 and the second thermocouple wire 17 are wound around each other, so that the interference of the electromagnetic field generated by the coil panel of the induction cooker on the thermoelectromotive force signal can be reduced, and the accuracy of the temperature information acquired by the micro control unit 15 can be improved.
In addition, in the present invention, the first thermocouple wire 16 and the second thermocouple wire 17 are wound around each other in a range from the temperature measurement point of the thermocouple to the input end of the inverting input circuit 11, that is, the first thermocouple wire 16 and the second thermocouple wire 17 are wound around each other in a range from the temperature measurement point of the thermocouple to the first end of the resistor R3.
Optionally, referring to fig. 3, the thermometry circuit further includes: common mode inductance L1.
The common mode inductor is also called a common mode choke, and generally, the common mode inductor L1 includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first thermocouple wire 16 is grounded through a common mode inductor L1, and the second thermocouple wire 17 is connected to a first end of a resistor R3 through a common mode inductor L1.
The positive output terminal of the thermocouple 10 is connected to the first input terminal of the common mode inductor L1 through the first portion of the first thermocouple wire 16, and the first output terminal of the common mode inductor L1 is grounded through the second portion of the first thermocouple wire 16; the negative output terminal of thermocouple 10 is connected to a second input terminal of common mode inductor L1 through a first portion of second thermocouple wire 16, and a second output terminal of common mode inductor L1 is connected to a first terminal of resistor R3 through a second portion of second thermocouple wire 17.
The utility model discloses in, through set up common mode inductance between the output of thermocouple and inverting input circuit, this common mode inductance can filter the electromagnetic interference signal of common mode to can reduce the electromagnetic field that the coil panel of electromagnetism stove produced to the interference of thermal electromotive force signal, improve the accuracy of the temperature information that little the control unit acquireed.
As shown in fig. 1, fig. 2 and fig. 3, in one possible implementation, the operational amplifier circuit 14 includes an operational amplifier 18 and a feedback network circuit 19.
In this embodiment, the operational amplifier 18 (the operational amplifier 18 may also be referred to as "operational amplifier") and the feedback network circuit 19 together form the operational amplifier circuit 14, which can amplify an input signal. The operational amplifier 18 may be in the form of a chip, or may be a circuit unit composed of a plurality of independent devices, which is not limited by the present invention.
Optionally, the feedback network circuit 19 includes a resistor R1 and a capacitor C1.
Specifically, the inverting input terminal of the operational amplifier 18 is connected to the second terminal of the inverting input circuit 11, the first terminal of the resistor R1, and the first terminal of the capacitor C1, respectively, the non-inverting input terminal of the operational amplifier 18 is connected to the non-inverting input circuit 12, and the output terminal of the operational amplifier 18 is connected to the second terminal of the resistor R1 and the second terminal of the capacitor C1, respectively.
The larger the resistance value of the resistor R1 is, the larger the amplification factor of the operational amplifier circuit 14 is.
Optionally, the resistance value of the resistor R1 is greater than 1M ohms.
The capacitor C1 is used for compensating the influence caused by the phase lag of the operational amplifier 18 and the parasitic capacitor, and the capacitor C1 can also be used for eliminating the self-oscillation generated by the thermometric circuit.
With reference to fig. 1, 2 and 3, the non-inverting input circuit 12 includes a resistor R4, wherein a first end of the resistor R4 is grounded, and the other end of the resistor R4 is connected to the non-inverting input of the operational amplifier 18, and the resistor R4 can be used to compensate the symmetry between the non-inverting input and the inverting input of the operational amplifier 18.
Alternatively, the resistance value of the resistor R4 is equal to the resistance value of the resistor R3.
In the temperature measurement circuit provided by this embodiment, because the input voltage of the non-inverting input terminal of the operational amplifier 18 is equal to zero, and further, the characteristic of the operational amplifier 18 makes the voltages of the inverting input terminal and the non-inverting input terminal of the operational amplifier 18 equal, and therefore, the voltage of the inverting input terminal of the operational amplifier 18 is also zero, so that the operational amplifier 18 has no common-mode signal input, that is, the temperature measurement circuit itself has a high common-mode rejection ratio, and the operational amplifier 18 has no common-mode rejection ratio requirement.
Referring to fig. 1, 2, and 3, the power supply circuit 13 includes a resistor R5 and a capacitor C5.
The first end of the resistor R5 is connected to the operational amplifier circuit 14 and the first end of the capacitor C5, the second end of the capacitor C5 is grounded, and the second end of the resistor R5 is connected to the power supply.
VCC shown in fig. 2 and fig. 3 is a power supply, where VCC is short for Volt Current concentrator, and means a power supply voltage of a circuit.
The power supply supplies an operating voltage to the operational amplifier circuit 14 through the resistor R5 in the power supply circuit 13, and the resistor R5 can reduce the influence of power supply noise on the operational amplifier 18.
Optionally, the resistance value of the resistor R5 is less than 100 ohms. In practical applications, the resistance value of the resistor R5 can be set according to actual requirements.
The capacitor C5 in the power circuit 13 is a filter capacitor, and the capacitor C5 can be used for filtering out interference signals in the electrical signal output by the power supply.
The utility model provides a temperature measurement circuit provides operating voltage to operational amplification circuit 14 through power supply circuit 13, makes the electric energy of exporting to operational amplification circuit 14 more stable, and disturbs for a short time. In this way, the output signal of the operational amplifier circuit 14 is further accurate, and the accuracy of the temperature information is improved.
Fig. 4 is a schematic structural diagram of the temperature measuring circuit provided by the present invention. As shown in fig. 4, the temperature measuring circuit of the present embodiment further includes, on the basis of the embodiments shown in fig. 2 and 3: and an output circuit 20.
Fig. 4 only shows the case where the first thermocouple wire 16 and the second thermocouple wire 17 are wound around each other, and it should be noted that, when the output end of the thermocouple 10 and the inverting input circuit 11 are connected as shown in fig. 3, the output circuit 20 may also be included between the operational amplifier circuit 14 and the micro control unit 15, and the connection manner may refer to the description in this embodiment.
The first end of the output circuit 20 is connected to the output end of the operational amplifier circuit 14, the second end of the output circuit 20 is connected to the micro control unit 15, the output circuit 20 is configured to filter and limit the current of the electrical signal output by the operational amplifier circuit, specifically, the output circuit 20 can filter the high-frequency noise generated by the operational amplifier in the operational amplifier circuit, and the output circuit 20 can limit the current input to the micro control unit.
Optionally, the output circuit 20 includes a capacitor C2 and a resistor R2, an output terminal of the operational amplifier circuit 14 is connected to a first terminal of the resistor R2 and a first terminal of the capacitor C2, a second terminal of the resistor R2 is connected to the micro control unit 15, and a second terminal of the capacitor C2 is grounded.
The capacitor C2 is a decoupling capacitor, and the capacitor C2 is specifically configured to filter high frequency noise output by the operational amplifier 18.
The resistor R2 is a current-limiting resistor, the resistor R2 is specifically used for limiting the current of the branch in which the capacitor R2 is located, and the micro control unit 15 can be effectively prevented from being damaged due to the fact that the current input to the micro control unit 15 is too large through the resistor R2.
The temperature measurement circuit provided by the embodiment not only reduces the requirements on the amplification performance of the operational amplifier 18 and the common mode rejection ratio, further, by arranging the output circuit 20, the influence of high-frequency noise of the operational amplifier 18 is filtered, the accuracy of the temperature information acquired by the micro control unit 15 is improved, and by arranging the resistor R2, the damage of the micro control unit 15 caused by the overlarge current input to the micro control unit 15 can be prevented, and the reliability of the temperature measurement circuit is further improved.
The embodiment also provides a cooking appliance, which comprises the temperature measuring circuit in any one of the above embodiments.
The cooking appliance may be an induction cooker, and the temperature measuring circuit according to any of the above embodiments may be used to measure the temperature of the top surface of the induction cooker.
Of course, the cooking appliance may be other types of cooking appliances, and is not limited to the above-mentioned induction cooker.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (11)
1. A thermometry circuit, comprising: a thermocouple (10), an inverting input circuit (11), a non-inverting input circuit (12), a power supply circuit (13), an operational amplifier circuit (14), and a micro control unit (15);
wherein a first end of the inverting input circuit (11) is connected with the thermocouple (10), a second end of the inverting input circuit (11) is connected with an inverting input end of the operational amplification circuit (14), and the non-inverting input circuit (12) is connected with a non-inverting input end of the operational amplification circuit (14);
the thermocouple (10) is used for collecting temperature information and converting the temperature information into a thermoelectromotive force signal; the inverting input circuit (11) is used for amplifying the thermal electromotive force signal to obtain a first input signal and transmitting the first input signal to an inverting input end of the operational amplification circuit (14); the non-inverting input circuit (12) is used for inputting a second input signal to a non-inverting input end of the operational amplification circuit (14);
the output end of the operational amplification circuit (14) is connected with the micro control unit (15), the operational amplification circuit (14) is also connected with the power supply circuit (13), the power supply circuit (13) is used for supplying working voltage to the operational amplification circuit (14), and the operational amplification circuit (14) is used for carrying out amplification processing according to the first input signal and the second input signal;
the micro control unit (15) is used for acquiring the temperature information according to the electric signal output by the operational amplification circuit (14).
2. Thermometry circuit according to claim 1, characterized in that said inverting input circuit (11) comprises: a resistor R3 and a capacitor C3;
the positive output end of the thermocouple (10) is grounded through a first thermocouple wire (16), the negative output end of the thermocouple (10) is connected to a first end of the resistor R3 through a second thermocouple wire (17), a second end of the resistor R3 is respectively connected with an inverting input end of the operational amplification circuit (14) and a first end of the capacitor C3, and a second end of the capacitor C3 is grounded.
3. The thermometric circuit of claim 2, wherein said first thermocouple wire (16) is intertwined with said second thermocouple wire (17).
4. The thermometric circuit of claim 2, further comprising: a common mode inductor L1, the first thermocouple wire (16) being connected to ground through the common mode inductor L1, and the second thermocouple wire (17) being connected to a first end of the resistor R3 through the common mode inductor L1.
5. The thermometric circuit according to claim 1, wherein the operational amplification circuit (14) comprises an operational amplifier (18) and a feedback network circuit (19), wherein the feedback network circuit (19) comprises a resistor R1 and a capacitor C1;
the inverting input end of the operational amplifier (18) is respectively connected with the second end of the inverting input circuit (11), the first end of the resistor R1 and the first end of the capacitor C1;
the non-inverting input end of the operational amplifier (18) is connected with the non-inverting input circuit (12);
the output end of the operational amplifier (18) is respectively connected with the second end of the resistor R1 and the second end of the capacitor C1.
6. The thermometric circuit according to claim 5, wherein the non-inverting input circuit (12) comprises a resistor R4, a first terminal of the resistor R4 is connected to ground, and a second terminal of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier circuit (14).
7. The thermometric circuit of claim 1, further comprising: an output circuit (20);
the first end of the output circuit (20) is connected with the output end of the operational amplification circuit (14), and the second end of the output circuit (20) is connected with the micro control unit (15).
8. The thermometric circuit according to claim 7, wherein the output circuit (20) comprises a capacitor C2 and a resistor R2, the output terminal of the operational amplifier circuit (14) is connected to a first terminal of the resistor R2 and a first terminal of the capacitor C2, respectively, a second terminal of the resistor R2 is connected to the micro-control unit (15), and a second terminal of the capacitor C2 is connected to ground.
9. Thermometric circuit according to claim 1, characterized in that said power supply circuit (13) comprises: a resistor R5 and a capacitor C5;
the first end of the resistor R5 is respectively connected with the operational amplifier circuit (14) and the first end of the capacitor C5, the second end of the capacitor C5 is grounded, and the second end of the resistor R5 is connected with a power supply.
10. The thermometric circuit according to claim 6, wherein the resistance R3 is equal in magnitude to the resistance R4, and/or the resistance R3 is greater than or equal to 10 kohms.
11. A cooking appliance comprising a thermometry circuit according to any one of claims 1 to 10.
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| CN201921619022.0U CN210833909U (en) | 2019-09-26 | 2019-09-26 | Temperature measurement circuit and cooking utensil |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114073412A (en) * | 2020-07-31 | 2022-02-22 | 浙江绍兴苏泊尔生活电器有限公司 | Temperature detection circuit and method and cooking utensil |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114073412A (en) * | 2020-07-31 | 2022-02-22 | 浙江绍兴苏泊尔生活电器有限公司 | Temperature detection circuit and method and cooking utensil |
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