Double-reference platinum resistor temperature measurement circuit and method

Abstract

The invention provides a double-reference platinum resistor temperature measurement circuit and method, which can be applied to the technical field of temperature measurement. The double-reference platinum resistor temperature measurement circuit comprises a current source, a platinum resistor, a first reference resistor and a second reference resistor which are sequentially connected in series, the channel selection module is used for electrically connecting the first target resistor with the first amplifier and electrically connecting the second target resistor with the second amplifier; the first amplifier performs differential amplification on the voltage at the two ends of the first target resistor to obtain a first voltage; the second amplifier performs differential amplification on the voltage at the two ends of the second target resistor to obtain a second voltage; the third amplifier performs differential amplification on the difference value between the first voltage and the second voltage to obtain an analog voltage; the analog-to-digital conversion module performs analog-to-digital conversion on the analog voltage to obtain a digital voltage; the processor obtains the resistance value of the platinum resistor according to the multiple digital voltages obtained in the multiple states, and determines the temperature of the environment where the platinum resistor is located according to the resistance value of the platinum resistor.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature measurement, and more specifically, to a platinum resistance temperature measurement circuit and method with dual references. Background Art

[0002] The platinum resistance temperature measurement circuit measures temperature by utilizing the characteristic that the resistance value of the platinum resistance changes with temperature. The temperature characteristic of the platinum resistance is stable and is commonly used in high-precision temperature measurements.

[0003] In the related art, when using the platinum resistance temperature measurement circuit to measure the ambient temperature, in the case of a relatively small change in the ambient temperature, most of the measurement ranges are wasted, and the cost of precise measurement is very high. Summary of the Invention

[0004] In view of this, the present invention provides a platinum resistance temperature measurement circuit and method with dual references.

[0005] According to one aspect of the present invention, there is provided a platinum resistance temperature measurement circuit with dual references, including: a current source, a platinum resistance, a first reference resistance, and a second reference resistance connected in series in sequence; a channel selection module for electrically connecting a first target resistance to a first amplifier and a second target resistance to a second amplifier, wherein the first target resistance and the second target resistance are both any one of the platinum resistance, the first reference resistance, and the second reference resistance, and the first target resistance and the second target resistance are different from each other; the first amplifier for differentially amplifying the voltage across the first target resistance to obtain a first voltage; the second amplifier for differentially amplifying the voltage across the second target resistance to obtain a second voltage; a third amplifier for differentially amplifying the difference between the first voltage and the second voltage to obtain an analog voltage; an analog-to-digital conversion module for performing analog-to-digital conversion on the analog voltage to obtain a digital voltage; and a processor for obtaining the resistance value of the platinum resistance according to a plurality of digital voltages obtained in a plurality of states, and determining the temperature of the environment where the platinum resistance is located according to the resistance value of the platinum resistance, wherein in the plurality of states, the direction of the excitation current output by the current source is different, and the connection manner between the platinum resistance, the first reference resistance, and the second reference resistance and the first amplifier and the second amplifier is different.

[0006] According to an embodiment of the present invention, the above-mentioned multiple digital voltages include: when the excitation current is in the first direction, a first digital voltage obtained when the first target resistance is the platinum resistance and the second target resistance is the first reference resistance; a second digital voltage obtained when the first target resistance is the second reference resistance and the second target resistance is the first reference resistance; a third digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the platinum resistance; a fourth digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the second reference resistance; when the excitation current is in the second direction, a fifth digital voltage obtained when the first target resistance is the platinum resistance and the second target resistance is the first reference resistance; a sixth digital voltage obtained when the first target resistance is the second reference resistance and the second target resistance is the first reference resistance; a seventh digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the platinum resistance; an eighth digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the second reference resistance.

[0007] According to an embodiment of the present invention, the processor obtains the resistance value of the platinum resistance according to the multiple digital voltages, including: obtaining a first pressure difference according to the first digital voltage, the third digital voltage, the fifth digital voltage, and the seventh digital voltage; obtaining a second pressure difference according to the second digital voltage, the fourth digital voltage, the sixth digital voltage, and the eighth digital voltage; obtaining a first ratio according to the first pressure difference and the second piezoresistive difference; obtaining the resistance value of the platinum resistance according to the first ratio, the resistance value of the first reference resistance, and the resistance value of the second reference resistance.

[0008] According to an embodiment of the present invention, the processor obtains a first pressure difference according to the first digital voltage, the third digital voltage, the fifth digital voltage, and the seventh digital voltage, including: obtaining a first difference according to the first digital voltage and the third digital voltage; obtaining a second difference according to the seventh digital voltage and the fifth digital voltage; obtaining the first pressure difference according to the first difference and the second difference; the processor obtains a second pressure difference according to the second digital voltage, the fourth digital voltage, the sixth digital voltage, and the eighth digital voltage, including: obtaining a third difference according to the second digital voltage and the fourth digital voltage; obtaining a fourth difference according to the eighth digital voltage and the sixth digital voltage; obtaining the second pressure difference according to the third difference and the fourth difference.

[0009] According to an embodiment of the present invention, the processor obtaining the resistance value of the platinum resistor based on the first ratio, the resistance value of the first reference resistor, and the resistance value of the second reference resistor includes: obtaining a first intermediate resistance value based on the resistance value of the second reference resistor and the resistance value of the first reference resistor; obtaining a second intermediate resistance value based on the intermediate reference resistance value and the first ratio; and obtaining the resistance value of the platinum resistor based on the second intermediate resistance value and the resistance value of the first reference resistor.

[0010] According to an embodiment of the present invention, the resistance value of the first reference resistor is set to be consistent with the minimum detectable resistance value of the platinum resistor, and the resistance value of the second reference resistor is set to be consistent with the maximum detectable resistance value of the platinum resistor.

[0011] According to an embodiment of the present invention, when the resolution of the analog-to-digital conversion module is 16 bits, the measurement range of the dual-reference platinum resistor temperature measurement circuit is 10 °C, and the resolution of the dual-reference platinum resistor temperature measurement circuit is 0.001 °C.

[0012] According to an embodiment of the present invention, the above-mentioned dual-reference platinum resistor temperature measurement circuit further includes: a first filter for denoising the first voltage to obtain a first filtered voltage; a second filter for denoising the second voltage to obtain a second filtered voltage; the third amplifier differentially amplifying the difference between the first voltage and the second voltage to obtain an analog voltage includes: differentially amplifying the difference between the first filtered voltage and the second filtered voltage to obtain the analog voltage.

[0013] According to an embodiment of the present invention, the first reference resistor and the second reference resistor are VHP202Z series resistors or RJ711 series resistors.

[0014] According to another aspect of the present invention, there is provided a dual-reference platinum resistance temperature measurement method, which is applied to the above-mentioned dual-reference platinum resistance temperature measurement circuit, and includes: a channel selection module electrically connects a first target resistor to a first amplifier, and electrically connects a second target resistor to a second amplifier, wherein the first target resistor and the second target resistor are both any one of a platinum resistor, a first reference resistor, and a second reference resistor, and the first target resistor and the second target resistor are different from each other; the first amplifier differentially amplifies the voltage across the first target resistor to obtain a first voltage; the second amplifier differentially amplifies the voltage across the second target resistor to obtain a second voltage; a third amplifier differentially amplifies the difference between the first voltage and the second voltage to obtain an analog voltage; an analog-to-digital conversion module performs analog-to-digital conversion on the analog voltage to obtain a digital voltage; a processor obtains the resistance value of the platinum resistor according to a plurality of digital voltages obtained in a plurality of states, and determines the temperature of the environment where the platinum resistor is located according to the resistance value of the platinum resistor, wherein in the plurality of states, the direction of the excitation current output by the current source is different, and the connection manner between the platinum resistor, the first reference resistor, and the second reference resistor and the first amplifier and the second amplifier is different.

[0015] According to the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention, through a current source, a platinum resistor, a first reference resistor, and a second reference resistor connected in series in sequence, the channel selection module electrically connects a first target resistor to a first amplifier, and electrically connects a second target resistor to a second amplifier. The first target resistor and the second target resistor are both any one of a platinum resistor, a first reference resistor, and a second reference resistor, and the first target resistor and the second target resistor are different from each other. The first amplifier differentially amplifies the voltage across the first target resistor to obtain a first voltage, the second amplifier differentially amplifies the voltage across the second target resistor to obtain a second voltage, the third amplifier differentially amplifies the difference between the first voltage and the second voltage to obtain an analog voltage, and the analog-to-digital conversion module is used to perform analog-to-digital conversion on the analog voltage to obtain a digital voltage. By using the technical means of performing analog-to-digital conversion on the analog voltage corresponding to the pressure difference between the resistors to obtain a digital voltage, compared with directly converting each voltage corresponding to the resistor in the related art, it is possible to perform data conversion only on the pressure difference corresponding to the actual temperature measurement range, reduce the conversion of voltage data corresponding to the unnecessary temperature measurement range, and thus the resolution requirement for the analog-to-digital conversion module is relatively low, and the cost of precise measurement is low.

[0016] According to the dual-reference platinum resistance temperature measurement circuit provided by the embodiments of the present invention, a processor is used to obtain the resistance value of the platinum resistance based on multiple digital voltages obtained in multiple states, and determine the temperature of the environment where the platinum resistance is located according to the resistance value of the platinum resistance. Among the multiple states, the direction of the excitation current output by the current source is different, and the connection manners between the platinum resistance, the first reference resistance, and the second reference resistance and the first amplifier and the second amplifier are different. By means of the cross-measurement method, the influences of factors such as the thermoelectric potential, the input offset voltage of the operational amplifier, and the long-term drift of the amplifier circuit in the temperature measurement circuit are offset, the requirement for the index of the operational amplifier device can be reduced, and a higher-precision temperature can be obtained at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0018] Figure 1 The structural schematic diagram of the existing temperature measurement circuit is shown;

[0019] Figure 2A The schematic diagram showing the change of the resistance value of the platinum resistance with temperature is shown;

[0020] Figure 2B The schematic diagram showing the change of the resistance value of another platinum resistance with temperature is shown;

[0021] Figure 3 The structural schematic diagram of the dual-reference platinum resistance temperature measurement circuit according to the embodiments of the present invention is shown;

[0022] Figure 4 The partial structural schematic diagram of the dual-reference platinum resistance temperature measurement circuit according to the embodiments of the present invention is shown;

[0023] Figure 5 The structural schematic diagram of the dual-reference platinum resistance temperature measurement circuit according to another embodiment of the present invention is shown;

[0024] Figure 6 The structural schematic diagram of the dual-reference platinum resistance temperature measurement circuit according to another embodiment of the present invention is shown;

[0025] Figure 7 The flowchart of the dual-reference platinum resistance temperature measurement method according to the embodiments of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0027] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "comprising", "including" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] In the case of using expressions such as "at least one of A, B, and C", generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C).

[0030] For an industrial platinum resistance thermometer, when the ambient temperature is -200°C to 0°C, the relationship between its resistance value and temperature is shown in Formula (1).

[0031] R pt =R 0 [1 + At + Bt 2 + C(t - 100)t 3 (1).

[0032] When the ambient temperature is 0°C to 850°C, the relationship between its resistance value and temperature is shown in Formula (2).

[0033] R pt =R 0 (1 + At + Bt 2 ) (2);

[0034] Wherein, R pt is the resistance value of the platinum resistance thermometer, R 0 is the resistance value of the platinum resistance thermometer at 0°C, A, B, and C are all coefficients, and t is the temperature. A, B, and C can be respectively: , and . For Pt100, R 0 = 100 Ω, and for Pt1000, R 0 = 1000 Ω.

[0035] The related platinum resistance temperature measurement circuit measures temperature by utilizing the characteristic that the resistance value of the platinum resistance changes with temperature.

[0036] For example, the platinum resistance temperature measurement circuit can first measure the resistance value of the platinum resistance and display the measured temperature according to the relationship between the resistance value of the platinum resistance and temperature. The essence of the platinum resistance temperature measurement circuit is to measure the resistance value of the platinum resistance

[0037] Figure 1 shows a schematic structural diagram of the existing temperature measurement circuit.

[0038] As Figure 1 shown, in the existing temperature measurement circuit, the target current source 101, the platinum resistance to be measured 102, and a target reference resistor 103 are connected in series. The target amplifier 104 can amplify the voltages across the platinum resistance to be measured 102 and the target reference resistor 103 respectively, obtaining the analog voltage across the platinum resistance to be measured 102 and the analog voltage across the reference resistor. The target analog-to-digital conversion module 105 can perform analog-to-digital conversion on the analog voltages across the platinum resistance to be measured 102 and the target reference resistor 103 respectively, obtaining the digital voltage across the platinum resistance to be measured 102 and the digital voltage across the target reference resistor 103.

[0039] From Figure 1 it can be known that: when the direct current I output by the target current source 101 flows through the series-connected platinum resistance to be measured 102 and the target reference resistor 103, since the current passing through the two resistors is the same, the voltage ratio measured on the two resistors is equal to the resistance ratio of the two resistors, as shown in formula (3). Therefore, the resistance value of the platinum resistance can be obtained by calculating the voltage ratio between the two resistors, and based on the voltage ratio and the reference resistor, and then the resistance value of the platinum resistance to be measured 102 is converted to obtain the corresponding temperature value.

[0040] (3);

[0041] where, R pt is the resistance value of the platinum resistance, Rs is the resistance value of the reference resistor, V pt is the digital voltage across the platinum resistance, and Vs is the digital voltage across the reference resistor.

[0042] Figure 2A shows a schematic diagram of the change of the resistance value of the platinum resistance with temperature.

[0043] InFigure 2A Among them, the abscissa is temperature and the ordinate is resistance value. The resistance value of the platinum resistor increases with the increase of temperature. The working temperature range of the platinum resistor is generally -200°C to 850°C. The change range of the resistance value of the platinum resistor is 0Ω to 400Ω.

[0044] In the related technologies, there is a need to measure the temperature in application scenarios with relatively small temperature changes by using the existing temperature measurement circuit in Figure 1 , that is, the small temperature range measurement requirement.

[0045] For example, in the cold atom experiment in physics, it is necessary to accurately measure the temperature of the surface of the experimental cavity and calculate the influence of the blackbody radiation of the cavity on the transition frequency of cold atoms. The experimental environment is already in a constant temperature environment of 20°C, and the temperature change of the cavity is within 20°C ± 1°C. To further measure the temperature of the cavity with high precision in this temperature range (19°C to 21°C), the measurement accuracy needs to reach the order of 0.001°C.

[0046] Figure 2B Fig. shows another schematic diagram of the change of the resistance value of a platinum resistor with temperature.

[0047] As Figure 2B shown, for Pt100, at 20°C, the resistance value is about 107.7935Ω, at 19°C, the resistance value is about 107.4049Ω, and at 21°C, the resistance value is about 108.1820Ω. That is, in the temperature measurement range of 19°C to 20°C, the resistance value change range is about 107.4Ω to 108.2Ω. For the temperature measurement ranges of other application scenarios , the corresponding resistance value change range can be calculated according to the relationship between the resistance value and temperature of the platinum resistor.

[0048] For Pt100, when the temperature changes by 1°C, the resistance value of Pt100 changes by about 0.4Ω. When the temperature changes by 0.001°C, the resistance value changes by about 0.4mΩ. Then for a temperature change of 0.001°C, the relative change in its own resistance value is about . The same is true for other types of platinum resistors such as Pt25 and Pt1000. For a temperature change of 0.001°C, the relative change in resistance value is about .

[0049] And for the existing temperature measurement circuit in Figure 1 , when the temperature resolution requirement is 0.001°C, the target analog-to-digital converter 105 needs to resolve of the relative change, then the number of bits of the target analog-to-digital converter 105 is at least: . In actual measurement, the commutation of the excitation current of the platinum resistor will be used, and the range requirement is higher. The actual resolution number of bits of the target analog-to-digital conversion module 105 is required to be more than 20 bits.

[0050] For special application scenarios, such as the space environment of satellites, using platinum resistors for precise temperature measurement in a small temperature range is also an important application. The high-precision temperature measurement circuit relies on a target analog-to-digital conversion module 105 with 24 bits or more. The selection of the target analog-to-digital conversion module 105 with high resolution bits and radiation resistance is very limited and costly.

[0051] As Figure 2A and 2B show, the existing temperature measurement circuit can measure a very large range, but the actual temperature range used in the application scenario of small temperature range measurement is very small, wasting most of the measurement range.

[0052] Moreover, although the actual temperature range used in the application scenario of small temperature range measurement is very small, the temperature resolution requirement is relatively high, which requires higher requirements for related devices in the temperature measurement circuit, such as the analog-to-digital converter, resulting in a very high cost for precise measurement.

[0053] To solve the technical problems existing in the related art, the embodiments of the present invention provide a dual-reference platinum resistor temperature measurement circuit and method, which can be applied to the technical field of temperature measurement.

[0054] Figure 3 FIG. shows a schematic structural diagram of a dual-reference platinum resistor temperature measurement circuit according to an embodiment of the present invention.

[0055] As Figure 3 shown, the dual-reference platinum resistor temperature measurement circuit may include a current source 301, a platinum resistor 302, a first reference resistor 303, a second reference resistor 304, a channel selection module 305, a first amplifier 306, a second amplifier 307, a third amplifier 308, an analog-to-digital conversion module 309, and a processor 310, which are connected in series in sequence.

[0056] The current source 301 can output a low-noise constant excitation current and has the function of current commutation.

[0057] The platinum resistor 302 can be a four-wire platinum resistor. The four-wire platinum resistor includes two current excitation terminals and two voltage measurement terminals. Four-wire measurement can eliminate the influence of wires. The platinum resistor 302 can also be a two-wire platinum resistor.

[0058] Both the first reference resistor 303 and the second reference resistor 304 are precision reference resistors. The resistance value of the first reference resistor 303 and the resistance value of the second reference resistor 304 are related to the resistance value of the platinum resistor 302 and the range of the dual-reference platinum resistor temperature measurement circuit.

[0059] The channel selection module 305 can be used to electrically connect the first target resistor to the first amplifier 306 and the second target resistor to the second amplifier 307. Herein, both the first target resistor and the second target resistor are any one of the platinum resistor 302, the first reference resistor 303, and the second reference resistor 303, and the first target resistor and the second target resistor are different from each other.

[0060] For example, the first target resistor can be the platinum resistor 302, and the second target resistor can be the first reference resistor 303. The first target resistor can be the second reference resistor 304, and the second target resistor can be the first reference resistor 303. The first target resistor can be the first reference resistor 303, and the second target resistor is the platinum resistor 302. The first target resistor can be the first reference resistor 303, and the second target resistor can be the second reference resistor 304.

[0061] For example, the channel selection module 305 can be selected to measure the voltage across the platinum resistor 302 by the first amplifier 306, and at the same time select the second amplifier 307 to measure the voltage across the first reference resistor 303. The channel selection module 305 has the function of selecting which resistor's voltage is measured by the amplifier.

[0062] The first amplifier 306 can be used to differentially amplify the voltage across the first target resistor to obtain a first voltage. The second amplifier 307 can be used to differentially amplify the voltage across the second target resistor to obtain a second voltage. The third amplifier 308 can be used to differentially amplify the difference between the first voltage and the second voltage to obtain an analog voltage.

[0063] The first amplifier 306, the second amplifier 307, and the third amplifier 308 can all be amplifiers for measuring differential signals, and an instrument amplifier with low noise can be selected.

[0064] The analog-to-digital conversion module 309 can be used to perform analog-to-digital conversion on the analog voltage to obtain a digital voltage.

[0065] The analog-to-digital conversion module 309 can include an analog-to-digital conversion chip and a reference power supply supporting the analog-to-digital conversion chip, and the reference power supply is used to provide a reference voltage for the analog-to-digital conversion chip.

[0066] The processor 310 can be used to obtain the resistance value of the platinum resistor according to the multiple digital voltages obtained in multiple states, and determine the temperature of the environment where the platinum resistor is located according to the resistance value of the platinum resistor. Among the multiple states, the direction of the excitation current output by the current source is different, and the connection modes between the platinum resistor, the first reference resistor, and the second reference resistor and the first amplifier and the second amplifier are different.

[0067] The dual-reference platinum resistance temperature measurement circuit may further include a main control module. The main control module is used to control other modules or devices to perform data acquisition and transmission.

[0068] According to the dual-reference platinum resistance temperature measurement circuit provided by the embodiments of the present invention, through a current source, a platinum resistance, a first reference resistance, and a second reference resistance connected in series in sequence, using a channel selection module to electrically connect a first target resistance to a first amplifier, and to electrically connect a second target resistance to a second amplifier, both the first target resistance and the second target resistance are any one of the platinum resistance, the first reference resistance, and the second reference resistance, the first target resistance and the second target resistance are different from each other, using the first amplifier to differentially amplify the voltage across the first target resistance to obtain a first voltage, using the second amplifier to differentially amplify the voltage across the second target resistance to obtain a second voltage, using a third amplifier to differentially amplify the difference between the first voltage and the second voltage to obtain an analog voltage, an analog-to-digital conversion module, which is used to perform analog-to-digital conversion on the analog voltage to obtain a digital voltage, using the analog-to-digital conversion module to perform analog-to-digital conversion on the analog voltage to obtain a digital voltage, by means of the technical means, it is realized that the analog conversion module is used to convert the analog voltage corresponding to the pressure difference between the resistors to obtain a digital voltage. Compared with directly converting each voltage corresponding to the resistor in the related art, it can only perform data conversion on the pressure difference corresponding to the actual temperature measurement range, reduce the conversion of voltage data corresponding to the unnecessary temperature measurement range, and thus the resolution requirement for the analog-to-digital conversion module is relatively low, and the cost of precise measurement is low.

[0069] Using a processor to obtain the resistance value of the platinum resistance according to multiple digital voltages obtained in multiple states, and to determine the temperature of the environment where the platinum resistance is located according to the resistance value of the platinum resistance. Among the multiple states, the direction of the excitation current output by the current source is different, and the connection modes between the platinum resistance, the first reference resistance, and the second reference resistance and the first amplifier and the second amplifier are different. By means of the technical means, it is realized that through the cross-measurement method, the influence of factors such as thermoelectric potential, operational amplifier input offset voltage, and long-term drift of the amplifier circuit in the dual-reference platinum resistance temperature measurement circuit is cancelled, the index requirements for the operational amplifier device can be reduced, and at the same time, a higher-precision temperature can be obtained.

[0070] The resistance value of the first reference resistance 303 is set to be consistent with the minimum detectable resistance value of the platinum resistance 302, and the resistance value of the second reference resistance 304 is set to be consistent with the maximum detectable resistance value of the platinum resistance 302. Among them, the minimum detectable resistance value represents the lower limit of the resistance value of the platinum resistance 302 that the dual-reference platinum resistance temperature measurement circuit can measure, and the maximum detectable resistance value represents the upper limit of the resistance value of the platinum resistance 302 that the dual-reference platinum resistance temperature measurement circuit can measure.

[0071] Figure 4The partial structural schematic diagram of a dual-reference platinum resistance temperature measurement circuit according to an embodiment of the present invention is shown.

[0072] As Figure 4 shown, the dual-reference platinum resistance temperature measurement circuit may include a current source 301, a platinum resistance 302, a first reference resistance 303, and a second reference resistance 304 connected in series in sequence. The voltage across the platinum resistance 302 may be V pt , the voltage across the first reference resistance 303 may be V s1 , and the voltage across the second reference resistance 304 may be V s2 .

[0073] It can be known from Figure 4 that the excitation current I output by the current source 301 flows through the series-connected platinum resistance 302, the first reference resistance 303, and the second reference resistance 304. The excitation current passing through the three resistors is the same. Therefore, the ratio of the difference in resistance values is equal to the ratio of the difference in voltage division. The specific ratio relationship is shown in formula (4).

[0074] (4);

[0075] wherein, R s1 is the resistance value of the first reference resistance, R s2 is the resistance value of the second reference resistance, V s1 is the digital voltage across the first reference resistance, and V s2 is the digital voltage across the second reference resistance.

[0076] The resistance value of the platinum resistance 302 obtained according to formula (4) is shown in formula (5).

[0077] (5).

[0078] It can be known from formula (5) that the resistance value of the second reference resistance 304 determines the upper limit of the resistance value of the platinum resistance 302 that the dual-reference platinum resistance temperature measurement circuit can measure, and the resistance value of the first reference resistance 303 determines the lower limit of the resistance value of the platinum resistance 302 that the dual-reference platinum resistance temperature measurement circuit can measure. And since the dual-reference platinum resistance temperature measurement circuit determines the temperature of the environment where the platinum resistance 302 is located according to the resistance value of the platinum resistance 302, it can also be said that the resistance value of the second reference resistance 304 determines the upper limit of the temperature measurement of the dual-reference platinum resistance temperature measurement circuit, and the resistance value of the first reference resistance 303 determines the lower limit of the temperature measurement of the dual-reference platinum resistance temperature measurement circuit.

[0079] Therefore, the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention can set the range of the resistance value of the platinum resistance 302 that the dual-reference platinum resistance temperature measurement circuit can measure by setting the resistance value of the first reference resistor 303 and the resistance value of the second reference resistor 304. Furthermore, the dual-reference platinum resistance temperature measurement circuit can only measure the resistance value of the platinum resistance 302 corresponding to the small temperature range, and only measure the temperature in the small temperature range according to the resistance value of the platinum resistance corresponding to the small temperature range, greatly improving the utilization rate of the measurement interval.

[0080] According to formula (5), the difference between the first voltage and the second voltage processed by the third amplifier 308 is between (V pt -V s1 )~(V s2 -V s1 ), which is smaller than the range of all voltages corresponding to the platinum resistance processed by the target amplifier 104 in Figure 1 . Therefore, the range of the analog voltage output by the third amplifier 308 is smaller than the range of the analog voltage output by the target amplifier 104 in Figure 1 . Therefore, when the subsequent analog-to-digital conversion module 309 processes the analog voltage output by the third amplifier 308, the resolution requirement of the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention for the analog-to-digital conversion module 309 will be less than the resolution requirement of the existing temperature measurement circuit in Figure 1 for the target analog-to-digital conversion module 105, thereby increasing the optional models of the analog-to-digital conversion module 309 and reducing the selection cost of the analog-to-digital conversion module 309.

[0081] Figure 5 FIG. shows a schematic structural diagram of a dual-reference platinum resistance temperature measurement circuit according to another embodiment of the present invention.

[0082] Figure 5 The difference between the dual-reference platinum resistance temperature measurement circuit in Figure 3 and the dual-reference platinum resistance temperature measurement circuit in Figure 5 is that the dual-reference platinum resistance temperature measurement circuit in shows that during the actual temperature measurement process, the thermoelectric potential ΔV pt introduced by the platinum resistance 302, the thermoelectric potential ΔV s1 introduced by the first reference resistor 303, the thermoelectric potential ΔV s2 introduced by the second reference resistor 304, the equivalent input offset voltage ΔV a1 introduced by the first amplifier 306, and the equivalent input offset voltage ΔV a2 introduced by the second amplifier 307. Among them, the amplification factor of the first amplifier 306 is A1, the amplification factor of the second amplifier 307 is A2, and the amplification factor of the third amplifier 308 is A3. The excitation current is in the first positive direction, and the positive excitation current is I 1, the excitation current is in the second direction which is reverse, and the reverse excitation current is I 2 .

[0083] From Figure 5 it can be seen that when actually measuring temperature using the dual-reference platinum resistance temperature measurement circuit provided by the embodiments of the present invention, the accuracy of temperature will be affected by the thermoelectric potential introduced by the platinum resistance and the reference resistance, the equivalent input offset voltage introduced by the amplifier circuit, and the unequal commutation currents of the excitation current. To improve the temperature accuracy, multiple cross-measurements can be completed by controlling the channel selection module 305 to eliminate the influence of the thermoelectric potential introduced by the platinum resistance and the reference resistance, the influence of the equivalent input offset voltage introduced by the amplifier circuit, and the influence of the unequal commutation currents of the excitation current.

[0084] For example, the following 8 cross-measurements can be performed to offset the influence of the thermoelectric potential introduced by the platinum resistance and the reference resistance, the influence of the equivalent input offset voltage introduced by the amplifier circuit, and the influence of the unequal commutation currents of the excitation current.

[0085] During the first measurement process, the excitation current is in the first direction, and the excitation current is I 1 , the first target resistance is the platinum resistance 302, and the second target resistance is the first reference resistance 303. The channel selection module 305 electrically connects the platinum resistance 302 to the first amplifier 306, and electrically connects the first reference resistance 303 to the second amplifier 307.

[0086] The output of the first amplifier 306 is:[[]] . Wherein, V A1（1） is the first voltage during the first measurement process.

[0087] The output of the second amplifier 307 is:[[]] . Wherein, V A2（1） is the second voltage during the first measurement process.

[0088] The analog voltage output by the third amplifier 308 is converted by the analog-to-digital conversion module 309 to:[[]] . Wherein, V A3（1） is the first digital voltage.

[0089] During the second measurement process, the excitation current is in the first direction, and the excitation current is I 1 , the first target resistance is the second reference resistance 304, and the second target resistance is the first reference resistance 303. The channel selection module 305 electrically connects the second reference resistance 304 to the first amplifier 306, and electrically connects the first reference resistance 303 to the second amplifier 307.

[0090] The output of the first amplifier 306 is:[[]] . Wherein, V A1（2）is the first voltage during the second measurement process.

[0091] The output of the second amplifier 307 is: . Where, V A2（2） is the second voltage during the second measurement process.

[0092] The analog voltage output by the third amplifier 308 after being converted by the analog-to-digital conversion module 309 is: . Where, V A3（2） is the second digital voltage.

[0093] During the third measurement process, the excitation current is in the first direction, the excitation current is I 1 , the first target resistance is the first reference resistance 303, and the second target resistance is the platinum resistance 302. The channel selection module 305 electrically connects the first reference resistance 303 to the first amplifier 306 and the platinum resistance 302 to the second amplifier 307.

[0094] The output of the first amplifier 306 is: . Where, V A1（3） is the first voltage during the third measurement process.

[0095] The output of the second amplifier 307 is: . Where, V A2（3） is the second voltage during the third measurement process.

[0096] The analog voltage output by the third amplifier 308 after being converted by the analog-to-digital conversion module 309 is: . Where, V A3（3） is the third digital voltage.

[0097] During the fourth measurement process, the excitation current is in the first direction, the excitation current is I 1 , the first target resistance is the first reference resistance 303, and the second target resistance is the second reference resistance 304. The channel selection module 305 electrically connects the first reference resistance 303 to the first amplifier 306 and the second reference resistance 304 to the second amplifier 307.

[0098] The output of the first amplifier 306 is: . Where, V A1（4） is the first voltage during the fourth measurement process.

[0099] The output of the second amplifier 307 is: . Where, V A2（4） is the second voltage during the fourth measurement process.

[0100] The analog voltage output by the third amplifier 308 after being converted by the analog-to-digital conversion module 309 is: Among them, V A3（4） is the fourth digital voltage.

[0101] During the fifth measurement, the excitation current is in the second direction, and the excitation current is I 2 , the first target resistance is the platinum resistance 302, and the second target resistance is the first reference resistance 303. The channel selection module 305 electrically connects the platinum resistance 302 to the first amplifier 306 and electrically connects the first reference resistance 303 to the second amplifier 307.

[0102] The output of the first amplifier 306 is: Among them, V A1（5） is the first voltage during the fifth measurement.

[0103] The output of the second amplifier 307 is: Among them, V A2（5） is the second voltage during the fifth measurement.

[0104] The analog voltage output by the third amplifier 308 is converted by the analog-to-digital conversion module 309 to: Among them, V A3（5） is the fifth digital voltage.

[0105] During the sixth measurement, the excitation current is in the second direction, and the excitation current is I 2 , the first target resistance is the second reference resistance 304, and the second target resistance is the first reference resistance 303. The channel selection module 305 electrically connects the second reference resistance 304 to the first amplifier 306 and electrically connects the first reference resistance 303 to the second amplifier 307.

[0106] The output of the first amplifier 306 is: Among them, V A1（6） is the first voltage during the sixth measurement.

[0107] The output of the second amplifier 307 is: Among them, V A2（6） is the second voltage during the sixth measurement.

[0108] The analog voltage output by the third amplifier 308 is converted by the analog-to-digital conversion module 309 to: Among them, V A3（6） is the sixth digital voltage.

[0109] During the seventh measurement, the excitation current is in the second direction, and the excitation current is I 2, the first target resistance is the first reference resistance 303, and the second target resistance is the platinum resistance 302. The channel selection module 305 electrically connects the first reference resistance 303 to the first amplifier 306 and the platinum resistance 302 to the second amplifier 307.

[0110] The output of the first amplifier 306 is: . Where, V A1（7） is the first voltage during the seventh measurement.

[0111] The output of the second amplifier 307 is: . Where, V A2（7） is the second voltage during the seventh measurement.

[0112] The analog voltage output by the third amplifier 308 after being converted by the analog-to-digital conversion module 309 is: . Where, V A3（7） is the seventh digital voltage.

[0113] During the eighth measurement, the excitation current is in the second direction, and the excitation current is I 2 , the first target resistance is the first reference resistance 303, and the second target resistance is the second reference resistance 304. The channel selection module 305 electrically connects the first reference resistance 303 to the first amplifier 306 and the second reference resistance 304 to the second amplifier 307.

[0114] The output of the first amplifier 306 is: . Where, V A1（8） is the first voltage during the eighth measurement.

[0115] The output of the second amplifier 307 is: . Where, V A2（8） is the second voltage during the eighth measurement.

[0116] The analog voltage output by the third amplifier 308 after being converted by the analog-to-digital conversion module 309 is: . Where, V A3（8） is the eighth digital voltage.

[0117] Multiple digital voltages may include: when the excitation current is in the first direction, the first target resistance is a platinum resistance, and the second target resistance is a first reference resistance, the obtained first digital voltage; when the first target resistance is a second reference resistance and the second target resistance is a first reference resistance, the obtained second digital voltage; when the first target resistance is a first reference resistance and the second target resistance is a platinum resistance, the obtained third digital voltage; when the first target resistance is a first reference resistance and the second target resistance is a second reference resistance, the obtained fourth digital voltage. When the excitation current is in the second direction, the first target resistance is a platinum resistance, and the second target resistance is a first reference resistance, the obtained fifth digital voltage; when the first target resistance is a second reference resistance and the second target resistance is a first reference resistance, the obtained sixth digital voltage; when the first target resistance is a first reference resistance and the second target resistance is a platinum resistance, the obtained seventh digital voltage; when the first target resistance is a first reference resistance and the second target resistance is a second reference resistance, the obtained eighth digital voltage.

[0118] The processor 310 obtaining the resistance value of the platinum resistance according to multiple digital voltages may include: obtaining a first pressure difference according to the first digital voltage, the third digital voltage, the fifth digital voltage, and the seventh digital voltage; obtaining a second pressure difference according to the second digital voltage, the fourth digital voltage, the sixth digital voltage, and the eighth digital voltage; obtaining a first ratio according to the first pressure difference and the second piezoresistive difference; and obtaining the resistance value of the platinum resistance according to the first ratio, the resistance value of the first reference resistance, and the resistance value of the second reference resistance.

[0119] For example, after the above 8 cross-measurements, Equation (6) can be obtained according to the measurement results of the first, third, fifth, and seventh times. Equation (7) can be obtained according to the measurement results of the second, fourth, sixth, and eighth times.

[0120] (6).

[0121] (7).

[0122] The processor 310 obtaining the first pressure difference according to the first digital voltage, the third digital voltage, the fifth digital voltage, and the seventh digital voltage includes: obtaining a first difference according to the first digital voltage and the third digital voltage; obtaining a second difference according to the seventh digital voltage and the fifth digital voltage; and obtaining the first pressure difference according to the first difference and the second difference.

[0123] For example, the processor 310 may subtract the first digital voltage from the third digital voltage to obtain the first difference. Subtract the seventh digital voltage from the fifth digital voltage to obtain the second difference. Add the first difference and the second difference to obtain the first pressure difference.

[0124] For example, the processor 310 can obtain the first pressure difference according to the following formula (8).

[0125] First pressure difference = V A3（1） - V A3（3） - V A3（5） + V A3（7） (8).

[0126] The processor 310 obtains the second pressure difference based on the second digital voltage, the fourth digital voltage, the sixth digital voltage, and the eighth digital voltage, including: obtaining a third difference according to the second digital voltage and the fourth digital voltage; obtaining a fourth difference according to the eighth digital voltage and the sixth digital voltage; and obtaining the second pressure difference according to the third difference and the fourth difference.

[0127] For example, the processor 310 can subtract the second digital voltage from the fourth digital voltage to obtain a third difference. Subtract the eighth digital voltage from the sixth digital voltage to obtain a fourth difference. Add the third difference and the fourth difference to obtain the second pressure difference.

[0128] For example, the processor 310 can obtain the second pressure difference according to the following formula (9).

[0129] Second pressure difference = V A3（2） - V A3（4） - V A3（6） + V A3（8） (9).

[0130] Taking the ratio of formula (6) and formula (7) can obtain formula (10).

[0131] (10).

[0132] The processor 310 obtains the first ratio based on the first pressure difference and the first piezoresistive difference, including obtaining the first ratio α according to the following formula (11).

[0133] (11).

[0134] The processor 310 obtains the resistance value of the platinum resistor based on the first ratio, the resistance value of the first reference resistor, and the resistance value of the second reference resistor, including: obtaining a first intermediate resistance value according to the resistance value of the second reference resistor and the resistance value of the first reference resistor; obtaining a second intermediate resistance value according to the intermediate reference resistance value and the first ratio; and obtaining the resistance value of the platinum resistor according to the second intermediate resistance value and the resistance value of the first reference resistor.

[0135] For example, the processor 310 subtracts the resistance value of the second reference resistor from the resistance value of the first reference resistor to obtain a first intermediate resistance value. Multiplies the intermediate reference resistance value by the first ratio to obtain a second intermediate resistance value. Adds the second intermediate resistance value and the resistance value of the first reference resistor to obtain the resistance value of the platinum resistor.

[0136] By combining Equation (10) and Equation (11), Equation (12) is obtained. For example, the processor 310 can obtain the resistance value of the platinum resistor according to Equation (12) below.

[0137] R pt =α(R s2 -R s1 ) + R s1 (12).

[0138] According to the dual-reference platinum resistor temperature measurement circuit provided by the embodiment of the present invention, after 8 cross-measurements, the influence of the thermoelectric potential introduced by the platinum resistor and the reference resistor, the influence of the equivalent input offset voltage introduced by the amplifier circuit, and the influence of the unequal commutation currents of the excitation current can be eliminated, and the resistance value of the platinum resistor can be accurately measured.

[0139] Figure 6 FIG. shows a schematic structural diagram of a dual-reference platinum resistor temperature measurement circuit according to another embodiment of the present invention.

[0140] As Figure 6 shown, the dual-reference platinum resistor temperature measurement circuit may include a current source 301, a platinum resistor 302, a first reference resistor 303, a second reference resistor 304, a channel selection module 305, a first amplifier 306, a second amplifier 307, a third amplifier 308, an analog-to-digital conversion module 309, a processor 310, a first filter 311, and a second filter 312 connected in series in sequence.

[0141] Figure 5 and Figure 3 The current source 301, the platinum resistor 302, the first reference resistor 303, the second reference resistor 304, the channel selection module 305, the first amplifier 306, the second amplifier 307, the analog-to-digital conversion module 309, and the processor 310 in

[0142] The first filter 311 can be used to reduce the noise of the first voltage to obtain a first filtered voltage. The second filter 312 can be used to reduce the noise of the second voltage to obtain a second filtered voltage.

[0143] The third amplifier 308 differentially amplifies the difference between the first voltage and the second voltage to obtain an analog voltage, which may include: differentially amplifying the difference between the first filtered voltage and the second filtered voltage to obtain an analog voltage.

[0144] Figure 6 The dual-reference platinum resistor temperature measurement circuit in

[0145] The third filter 313 is used to reduce the noise of the voltage across the first target resistor to obtain a third filtered voltage. The fourth filter 314 is used to reduce the noise of the voltage across the second target resistor to obtain a fourth filtered voltage.

[0146] The first amplifier 306 differentially amplifies the voltage across the first target resistor to obtain a first voltage, which may include: differentially amplifying the third filtered voltage to obtain the first voltage. The second amplifier 307 differentially amplifies the voltage across the second target resistor to obtain a second voltage, which may include: differentially amplifying the fourth filtered voltage to obtain the second voltage.

[0147] To obtain a higher-precision temperature, appropriate selection of each device included in the double-reference platinum resistance temperature measurement circuit provided in the embodiments of the present invention can be made.

[0148] For example, the first reference resistor and the second reference resistor can be selected as low-temperature-drift precision resistors. The resistance values of the first reference resistor and the second reference resistor can be selected according to the resistance value of the platinum resistor and the range of the double-reference platinum resistance temperature measurement circuit. For example, for a precision temperature measurement range of t 1 ~t 2 corresponding to a platinum resistor with a resistance value of R pt1 ~R pt2 , the resistance value R s1 =R pt1 of the first reference resistor and the resistance value R s2 =R pt2 of the second reference resistor can be selected.

[0149] For example, the first reference resistor and the second reference resistor can be hermetically sealed alloy foil resistors such as VHP202Z series resistors. The first reference resistor and the second reference resistor can also be alloy foil resistors such as RJ711 series resistors.

[0150] The first amplifier, the second amplifier, and the third amplifier can use low-noise instrumentation amplifiers, and the key index is low low-frequency noise. For example, they can be common instrumentation amplifiers such as AD620, AD8421, ADA4523-1, etc. The amplification factors of the first amplifier and the second amplifier should be as large as possible to reduce the influence of the output noise on the equivalent input noise. The third amplifier should amplify the input voltage signal into the input range of the analog-to-digital conversion module as much as possible.

[0151] The channel selection module can select a relay or an analog switch. When the channel selection module is an analog switch, the key index of the analog switch is low leakage current. For example, analog switches such as ADG526A, ADG527A, or SF507AMDRH can be selected.

[0152] The analog-to-digital conversion module calculates the required number of bits according to the required temperature resolution. In the range of t 1 ~t 2 , when the temperature measurement resolution requirement is Δt, the number of bits required by the analog-to-digital conversion module is . In actual measurement, the measurement of positive and negative voltages will be used, and the required number of bits needs to be increased by 1, that is, the number of bits required by the analog-to-digital conversion module in actual measurement is .

[0153] For example, when the temperature of the object to be measured needs to be controlled and stabilized at a constant temperature of 20°C, the high-precision temperature measurement range is 18°C to 22°C, and the temperature resolution is 0.001°C, the number of bits required for the analog-to-digital conversion module is as follows: , then an analog-to-digital conversion module with 14 bits or more needs to be selected to achieve a temperature resolution of 0.001°C. At this time, a 16-bit resolution AD677 can be used to achieve a 10°C range and a 0.001°C resolution.

[0154] Therefore, for the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention, when the resolution of the analog-to-digital conversion module is 16 bits, the range of the dual-reference platinum resistance temperature measurement circuit can be 10°C, and the resolution of the dual-reference platinum resistance temperature measurement circuit can be 0.001°C.

[0155] The selection of the reference power supply for the analog-to-digital conversion module can be selected according to the selection of the analog-to-digital conversion module. The key index is that the noise should be small. For example, when the analog-to-digital conversion module is AD677, the reference power supply for the analog-to-digital conversion module can be selected as AD586.

[0156] According to the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention, a differential bridge circuit is designed, which can achieve high-precision temperature measurement of platinum resistance at the 0.001°C level within a 10°C temperature range. Commercial temperature measurement circuits with the same precision generally use analog-to-digital conversion modules with more than 24 bits and high-precision reference power supplies. The dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention has a lower cost.

[0157] According to the dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention, through the cross-measurement method corresponding to the differential bridge circuit, the influence of factors such as thermoelectric potential, operational amplifier input offset voltage, and long-term drift of the amplifier circuit in the dual-reference platinum resistance temperature measurement circuit can be offset, and the index requirements for the operational amplifier chip can be reduced.

[0158] The dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention has low requirements for the analog-to-digital conversion module and the reference power supply for the analog-to-digital conversion module, and is very suitable for scenarios with high requirements for circuit reliability or requirements for domesticating devices, such as satellites. Devices with rich flight experience that are commonly used can meet the index requirements of this circuit, and domestic devices can also meet the index requirements of this circuit.

[0159] The dual-reference platinum resistance temperature measurement circuit provided by the embodiment of the present invention has a simple design structure and can conveniently expand the measurement channels.

[0160] Based on the above dual-reference platinum resistance temperature measurement circuit, an embodiment of the present invention provides a dual-reference platinum resistance temperature measurement method.

[0161] Figure 7 The flowchart of the dual-reference platinum resistance temperature measurement method according to the embodiment of the present invention is shown. This dual-reference platinum resistance temperature measurement method can be applied to the above dual-reference platinum resistance temperature measurement circuit.

[0162] As Figure 7 shown, the dual-reference platinum resistance temperature measurement method may include operation S710 to operation S760.

[0163] In operation S710, the channel selection module electrically connects the first target resistor to the first amplifier and the second target resistor to the second amplifier, where the first target resistor and the second target resistor are both any one of the platinum resistor, the first reference resistor, and the second reference resistor, and the first target resistor and the second target resistor are different from each other.

[0164] In operation S720, the first amplifier differentially amplifies the voltage across the first target resistor to obtain a first voltage.

[0165] In operation S730, the second amplifier differentially amplifies the voltage across the second target resistor to obtain a second voltage.

[0166] In operation S740, the third amplifier differentially amplifies the difference between the first voltage and the second voltage to obtain an analog voltage.

[0167] In operation S750, the analog-to-digital conversion module performs analog-to-digital conversion on the analog voltage to obtain a digital voltage.

[0168] In operation S760, the processor obtains the resistance value of the platinum resistor based on the multiple digital voltages obtained in multiple states, and determines the temperature of the environment where the platinum resistor is located according to the resistance value of the platinum resistor. Among the multiple states, the direction of the excitation current output by the current source is different, and the connection modes between the platinum resistor, the first reference resistor, and the second reference resistor and the first amplifier and the second amplifier are different.

[0169] It should be noted that in the embodiments of the present invention, the dual-reference platinum resistance temperature measurement method part corresponds to the dual-reference platinum resistance temperature measurement circuit part. For the description of the dual-reference platinum resistance temperature measurement method part, please specifically refer to the dual-reference platinum resistance temperature measurement circuit part. For the sake of simplicity, it will not be elaborated here.

[0170] Those skilled in the art can understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0171] The embodiments of the present invention have been described above. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present invention is defined by the appended embodiments and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. A dual-reference platinum resistance temperature measurement circuit, characterized in that: include: A current source, a platinum resistor, a first reference resistor, and a second reference resistor connected in series in sequence; a channel selection module, configured to electrically connect a first target resistor to a first amplifier, and to electrically connect a second target resistor to a second amplifier, wherein the first target resistor and the second target resistor are any one of the platinum resistor, the first reference resistor, and the second reference resistor, and the first target resistor and the second target resistor are different from each other; The first amplifier is used to differentially amplify the voltage across the first target resistor to obtain a first voltage; The second amplifier is used to differentially amplify the voltage across the second target resistor to obtain a second voltage; a third amplifier, configured to differentially amplify a difference between the first voltage and the second voltage to obtain an analog voltage; An analog-to-digital conversion module, used for performing analog-to-digital conversion on the analog voltage to obtain a digital voltage; A processor is used to obtain the resistance value of the platinum resistor according to multiple digital voltages obtained in multiple states, and determine the temperature of the environment in which the platinum resistor is located according to the resistance value of the platinum resistor, wherein in the multiple states, the direction of the excitation current output by the current source is different, and the connection method between the platinum resistor, the first reference resistor and the second reference resistor and the first amplifier and the second amplifier is different.

2. The circuit according to claim 1, characterized in that The plurality of digital voltages include: When the excitation current is in the first direction, The first digital voltage obtained when the first target resistance is the platinum resistance and the second target resistance is the first reference resistance; the second digital voltage obtained when the first target resistance is the second reference resistance and the second target resistance is the first reference resistance; the third digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the platinum resistance; the fourth digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the second reference resistance; When the excitation current is in the second direction, The fifth digital voltage obtained when the first target resistance is the platinum resistance and the second target resistance is the first reference resistance; the sixth digital voltage obtained when the first target resistance is the second reference resistance and the second target resistance is the first reference resistance; the seventh digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the platinum resistance; the eighth digital voltage obtained when the first target resistance is the first reference resistance and the second target resistance is the second reference resistance.

3. The circuit according to claim 2, characterized in that The processor obtains the resistance value of the platinum resistor according to the multiple digital voltages, including: Obtaining a first voltage difference according to the first digital voltage, the third digital voltage, the fifth digital voltage and the seventh digital voltage; obtaining a second voltage difference according to the second digital voltage, the fourth digital voltage, the sixth digital voltage and the eighth digital voltage; Obtaining a first ratio according to the first pressure difference and the second piezoresistance difference; The resistance value of the platinum resistor is obtained according to the first ratio, the resistance value of the first reference resistor and the resistance value of the second reference resistor.

4. The circuit according to claim 3, characterized in that The processor obtains a first voltage difference according to the first digital voltage, the third digital voltage, the fifth digital voltage, and the seventh digital voltage, including: Obtaining a first difference value according to the first digital voltage and the third digital voltage; Obtaining a second difference value according to the seventh digital voltage and the fifth digital voltage; Obtaining the first pressure difference according to the first difference and the second difference; The processor obtains a second voltage difference according to the second digital voltage, the fourth digital voltage, the sixth digital voltage, and the eighth digital voltage, including: Obtaining a third difference value according to the second digital voltage and the fourth digital voltage; Obtaining a fourth difference value according to the eighth digital voltage and the sixth digital voltage; The second pressure difference is obtained according to the third difference and the fourth difference.

5. The circuit according to claim 4, characterized in that The processor obtains the resistance value of the platinum resistor according to the first ratio, the resistance value of the first reference resistor, and the resistance value of the second reference resistor, including: Obtaining a first intermediate resistance value according to the resistance value of the second reference resistor and the resistance value of the first reference resistor; Obtaining a second intermediate resistance value according to the intermediate reference resistance value and the first ratio; The resistance value of the platinum resistor is obtained according to the second intermediate resistance value and the resistance value of the first reference resistor.

6. The circuit according to any one of claims 1 to 5, characterized in that: The resistance value of the first reference resistor is set to be consistent with the minimum detectable resistance value of the platinum resistor, and the resistance value of the second reference resistor is set to be consistent with the maximum detectable resistance value of the platinum resistor.

7. The circuit according to any one of claims 1 to 5, characterized in that: When the resolution of the analog-to-digital conversion module is 16 bits, the range of the dual-reference platinum resistance temperature measurement circuit is 10° C., and the resolution of the dual-reference platinum resistance temperature measurement circuit is 0.001° C.

8. The circuit according to claim 7, characterized in that Also includes: A first filter, used for reducing noise on the first voltage to obtain a first filtered voltage; a second filter, used for performing noise reduction on the second voltage to obtain a second filtered voltage; The third amplifier differentially amplifies the difference between the first voltage and the second voltage to obtain an analog voltage, which includes: The difference between the first filtered voltage and the second filtered voltage is differentially amplified to obtain the analog voltage.

9. The circuit according to claim 2, characterized in that The first reference resistor and the second reference resistor are VHP202Z series resistors or RJ711 series resistors.

10. A dual-reference platinum resistance temperature measurement method, applied to the dual-reference platinum resistance temperature measurement circuit according to any one of claims 1 to 9, characterized in that: include: The channel selection module electrically connects the first target resistor to the first amplifier, and electrically connects the second target resistor to the second amplifier, wherein the first target resistor and the second target resistor are any one of a platinum resistor, a first reference resistor, and a second reference resistor, and the first target resistor and the second target resistor are different from each other; The first amplifier differentially amplifies the voltage across the first target resistor to obtain a first voltage; The second amplifier differentially amplifies the voltage across the second target resistor to obtain a second voltage; The third amplifier performs differential amplification on the difference between the first voltage and the second voltage to obtain an analog voltage; The analog-to-digital conversion module performs analog-to-digital conversion on the analog voltage to obtain a digital voltage; The processor obtains the resistance value of the platinum resistor based on multiple digital voltages obtained in multiple states, and determines the temperature of the environment in which the platinum resistor is located based on the resistance value of the platinum resistor, wherein in the multiple states, the direction of the excitation current output by the current source is different, and the connection methods between the platinum resistor, the first reference resistor, the second reference resistor and the first amplifier and the second amplifier are different.

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