CN117968879A - High-precision temperature measurement device and system - Google Patents
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Abstract
The embodiment of the application provides a high-precision temperature measurement device and a system, comprising: the temperature measuring device comprises a first transformer, a temperature measuring bridge, a second transformer, a signal detection circuit and a signal processing circuit; the secondary output end of the second transformer is connected with the signal input end of the signal detection circuit; the temperature measuring bridge is used for outputting a current signal for reflecting temperature change when the resistance value of the temperature measuring resistor changes along with the temperature change and the temperature measuring bridge deviates from a balance state after the sine wave signal is input to the primary side of the first transformer; the signal detection circuit is used for processing the current signal to obtain a temperature change signal; the signal processing circuit is used for processing the temperature change signal to obtain a temperature value. The device can improve the temperature measurement precision and meet the temperature measurement requirement in a high-precision temperature measurement scene.
Description
Technical Field
The embodiment of the application relates to the technical field of temperature measurement, in particular to a high-precision temperature measurement device and a high-precision temperature measurement system.
Background
In seismic observation, the likelihood of an earthquake is generally determined by monitoring the dynamic changes in subsurface stresses. Because of the difficulty in directly observing the stress change of the rock, in the process of sub-instability before earthquake, the relationship exists between the temperature and the stress strain, so that the change of the stress strain can be indirectly measured through the temperature. In the sub-destabilization stage, weak temperature raising and lowering processes are arranged at measuring points near the fault, the temperature change range is small, and in the order of 0.1mK, the resolution of the temperature measuring device is required to reach the order of 10 mu K in order to achieve enough observation signal-to-noise ratio. In addition, in gravitational wave detection, in order to realize the monitoring and regulation of the temperature field of the gravitational wave detector core instrument under the micro scale, the satellite-borne temperature measurement is required to have a resolution better than 5 mu K/[ V ] Hz@1 Hz-0.1 Hz.
Disclosure of Invention
In view of the above, an objective of the embodiments of the present application is to provide a high-precision temperature measurement device and system.
Based on the above object, an embodiment of the present application provides a high-precision temperature measurement device, including: the temperature measuring device comprises a first transformer, a temperature measuring bridge, a second transformer, a signal detection circuit and a signal processing circuit; the secondary output end of the second transformer is connected with the signal input end of the signal detection circuit;
The temperature measuring bridge is used for outputting a current signal for reflecting temperature change when the resistance value of the temperature measuring resistor changes along with the temperature change and the temperature measuring bridge deviates from a balance state after the sine wave signal is input to the primary side of the first transformer;
The signal detection circuit is used for processing the current signal to obtain a temperature change signal;
the signal processing circuit is used for processing the temperature change signal to obtain a temperature value.
Optionally, the signal detection circuit processes the current signal to obtain a temperature change signal, which is expressed as:
Wherein N is the number of turns of the primary coil of the first transformer, U m is a sine wave signal, N 1、N2 is the number of turns of the secondary coil of the first transformer, N p is the number of turns of the primary coil of the second transformer, N s is the number of turns of the secondary coil of the second transformer, R t is the resistance of the temperature measuring resistor, R r is the resistance of the reference resistor, and R 1 is the resistance of the resistor connected between the input end and the output end of the signal detection circuit.
Optionally, the temperature measuring resistor is a thermistor, and the signal processing circuit processes the temperature change signal to obtain a temperature value, which is expressed as:
Wherein B is the material constant of the thermistor, T 25 represents 25 ℃, and R t25 is the resistance value of the thermistor at 25 ℃.
Optionally, the temperature measuring resistor is a platinum resistor, and the signal processing circuit processes the temperature change signal to obtain a temperature value, which is expressed as:
Wherein, alpha is the temperature drift coefficient of the platinum resistor, and R 0 is the resistance value of the platinum resistor at the temperature of 0 ℃.
Optionally, the device further comprises an analog-to-digital conversion circuit and a bridge supply alternating voltage signal acquisition circuit;
The bridge supply alternating current voltage signal acquisition circuit is used for acquiring voltage signals of a first coil of a secondary side of the first transformer;
The analog-to-digital conversion circuit is used for converting the temperature change signal into a digital temperature change signal; and converting the voltage signal to a digital voltage signal;
the signal processing circuit processes the temperature change signal to obtain a temperature value, and the signal processing circuit comprises:
performing discrete Fourier transform on the digital temperature change signal to obtain the amplitude of the digital temperature change signal;
Performing discrete Fourier transform on the digital voltage signal to obtain the amplitude of the digital voltage signal;
and calculating to obtain a temperature value according to the type of the temperature measuring resistor, the circuit parameter, the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal.
Optionally, calculating a temperature value according to the type of the temperature measuring resistor, a circuit parameter, the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal, including:
and calculating to obtain a temperature value according to the type of the temperature measuring resistor, the circuit parameter, the ratio between the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal.
Optionally, the temperature measuring bridge comprises at least one group of reference resistors which can be switched on by a switch, and the resistance values of the reference resistors in each group are different.
Optionally, at least two groups of coil windings and corresponding taps are arranged on the secondary side of the first transformer.
Optionally, the signal detection circuit includes a current-voltage conversion circuit composed of a first amplifier, a resistor R 1、R2 and a capacitor C 1, an integration circuit composed of a second amplifier, a resistor R 3 and a capacitor C 2, and a resistor attenuation network composed of resistors R 4 and R 5; one end of a secondary coil of the second transformer is connected with the reverse input end of the first amplifier, and the other end of the secondary coil of the second transformer is grounded; the first end of the resistor R 1 and the first end of the capacitor C 1 are connected with the reverse input end of the first amplifier, the output end of the first amplifier is connected with the second end of the capacitor C 1 and the first end of the resistor R 2, and the second end of the resistor R 1 is connected with the second end of the resistor R 2 to form the output end of the signal detection circuit; the output end of the signal detection circuit is connected with the reverse input end of the second amplifier through a resistor R 3, the reverse input end of the second amplifier is connected with the output end of the second amplifier through a capacitor C 2, the positive input end of the second amplifier is grounded, and the output end of the second amplifier is connected with the positive input end of the first amplifier through a resistor attenuation network.
The embodiment of the application also provides a high-precision temperature measurement system which comprises at least one group of high-precision temperature measurement devices.
From the above, it can be seen that the high-precision temperature measurement device and system provided by the embodiment of the application include: the temperature measuring bridge is used for outputting a current signal used for reflecting temperature change when the resistance value of the temperature measuring resistor changes along with temperature change and the temperature measuring bridge deviates from a balance state after a sine wave signal is input to the primary side of the first transformer, the signal detecting circuit is used for processing the current signal to obtain a temperature change signal, and the signal processing circuit is used for processing the temperature change signal to obtain a temperature value. The device can improve the temperature measurement precision, reach the measurement resolution of 5 mu K level in the frequency band of 1 mHz-0.1 Hz, and meet the temperature measurement requirement in a high-precision temperature measurement scene.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of a device according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a portion of a circuit of an apparatus according to an embodiment of the present application;
FIG. 3 is a block diagram of a device according to another embodiment of the present application;
FIG. 4 is a schematic diagram of a portion of a circuit of a device according to another embodiment of the present application;
fig. 5 is a block diagram of a system architecture according to an embodiment of the present application.
Detailed Description
For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same.
It should be noted that unless otherwise defined, technical or scientific terms used in the embodiments of the present application should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present disclosure pertains. The terms "first," "second," and the like, as used in embodiments of the present application, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
As described in the background section, in the case of seismic observation, stress changes can be measured indirectly by measuring temperature, and in this scenario, since the temperature change amount is on the order of 0.1mK, a temperature measuring device is required to have extremely high resolution. In the field of gravitational wave detection, temperature measuring devices with extremely high resolution are also required. The common temperature measuring device is realized based on a temperature measuring resistor, and has simple circuit structure and wide application. However, the measurement resolution is not high due to the influence of the noise of components such as resistors, operational amplifiers, power supplies and the like, circuit noise and other factors, and the high-precision temperature measurement requirement in the application scene is difficult to meet in the mK level generally.
In view of the above, the embodiment of the application provides a high-precision temperature measurement device, which adopts an ac excitation signal to drive a temperature measuring bridge, outputs a current signal reflecting temperature change when the temperature measuring bridge deviates from a balance state, detects the current signal output by the temperature measuring bridge by using a current-coupled signal detection circuit, converts the current signal into a temperature change signal, and performs frequency domain processing on the temperature change signal by using a signal processing circuit to obtain a temperature value, thereby reducing noise influence, improving temperature measurement precision, and meeting the temperature measurement requirement of a high-precision temperature measurement scene.
The technical scheme of the application is further described in detail through specific examples.
As shown in fig. 1 and 2, a high-precision temperature measurement device provided by an embodiment of the present application includes: the temperature measuring device comprises a first transformer, a temperature measuring bridge, a second transformer, a signal detection circuit and a signal processing circuit; the secondary output end of the second transformer is connected with the signal input end of the signal detection circuit;
The temperature measuring bridge is used for outputting a current signal for reflecting temperature change when the resistance value of the temperature measuring resistor changes along with the temperature change and the temperature measuring bridge deviates from a balance state after the sine wave signal is input to the primary side of the first transformer;
The signal detection circuit is used for processing the current signal to obtain a temperature change signal;
And the signal processing circuit is used for processing the temperature change signal to obtain a temperature value.
As shown in the figure, the high-precision temperature measurement device provided in this embodiment includes a first transformer T 1, a temperature measurement bridge, a second transformer T 2, a signal detection circuit and a signal processing circuit. The primary coil of the first transformer T 1 is connected with an alternating current excitation signal source and is used for providing sine wave signals for the temperature measuring bridge; the secondary coil of the first transformer T 1 is provided with at least one tap, one tap is connected according to the temperature measurement range, and an inductance formed by two windings of the secondary coil, a temperature measuring resistor R t and a reference resistor R r form a temperature measuring bridge; the output end of the temperature measuring bridge is connected with the primary coil of the second transformer T 2, and the secondary output after current coupling through the second transformer T 2 is connected with the input end of the signal detection circuit.
In some embodiments, the signal detection circuit includes a current-to-voltage conversion circuit comprising a first amplifier a 1, a resistor R 1、R2, a capacitor C 1, an integration circuit comprising a second amplifier a 2, a resistor R 3, and a capacitor C 2, and a resistor attenuation network comprising a resistor R 4、R5.
One end of the secondary coil of the second transformer T 2 is connected with the reverse input end of the first amplifier A 1, and the other end of the secondary coil of the second transformer T 2 is grounded; the first end of the resistor R 1 and the first end of the capacitor C 1 are connected with the reverse input end of the first amplifier A 1, the output end of the first amplifier A 1 is connected with the second end of the capacitor C 1 and the first end of the resistor R 2, the second end of the resistor R 1 is connected with the second end of the resistor R 2, the resistor R 2 and the capacitor C 1 are used for improving the stability of the current-voltage conversion circuit, and the second end of the resistor R 1 and the second end of the resistor R 2 form the output end of the signal detection circuit. After the current signal output by the temperature measuring bridge passes through the current-voltage conversion circuit, the current signal is converted into a voltage signal, and the voltage signal V o, namely a temperature change signal, is output by the output end of the signal detection circuit.
In order to solve the problem of zero drift, the output end of the signal detection circuit is connected with the input end of the first amplifier A 1 through an integrating circuit and a resistor attenuation network to offset the zero drift. Specifically, the output end of the signal detection circuit is connected with the reverse input end of the second amplifier a 2 through a resistor R 3, the reverse input end of the second amplifier a 2 is connected with the output end of the second amplifier a 2 through a capacitor C 2, the positive input end of the second amplifier a 2 is grounded, and the output end of the second amplifier a 2 is connected with the positive input end of the first amplifier a 1 through a resistor attenuation network; the temperature change signal output by the output end of the signal detection circuit is fed back to the positive input end of the first amplifier A 1 after being divided by the integrating circuit and the resistor, and the feedback signal is used for canceling zero drift of the input end of the first amplifier.
The temperature measuring bridge is an alternating current bridge consisting of an inductor formed by two windings of a secondary coil of the first transformer T 1, a temperature measuring resistor R t and a reference resistor R r. When the AC bridge is in a balanced state, N 1Rr＝N2Rt, the output of the AC bridge is 0; when the external temperature changes to cause the resistance value of the temperature measuring resistor to change, the alternating current bridge deviates from the balance state, and the alternating current bridge outputs a current signal capable of reflecting the resistance value change of the temperature measuring resistor, namely the temperature change. After the current signal is converted by the current-voltage conversion circuit consisting of the first amplifier a 1 and the second transformer T 2, the signal detection circuit outputs a voltage signal V o capable of reflecting temperature change, namely a temperature change signal, wherein the temperature change signal is related to a sine wave signal, a circuit parameter, a resistance value of a temperature measuring resistor and the like, and can be expressed as:
Wherein N is the number of turns of the primary coil of the first transformer, U m is a sine wave signal of ac excitation, N 1、N2 is the number of turns of the two secondary winding coils of the first transformer, N p is the number of turns of the primary coil of the second transformer, N s is the number of turns of the secondary coil of the second transformer, R t is the resistance of the temperature measuring resistor, R r is the resistance of the reference resistor, and R 1 is the resistance of the resistor connected between the input end and the output end of the signal detection circuit.
When the primary input of the first transformer is a sine wave signal, the temperature change signal output by the signal detection circuit is an analog sine wave signal with the same frequency as the sine wave signal, so that the resistance change of the temperature measuring resistor can be reflected, the temperature change is sensed, and the temperature measurement is realized.
The relation between the temperature change signal V O and the resistance value R t of the temperature measuring resistor is shown in the formula (1), and the formula (1) is transformed to obtain an expression for representing the temperature measuring resistor by the temperature change signal:
On the basis of a temperature change signal V O in the formula (1), deriving a temperature measuring resistor R t to obtain the sensitivity of the detected temperature change signal to the temperature measuring resistor, wherein the sensitivity is expressed as follows:
In some embodiments, the signal processing circuit is configured to process the temperature change signal to obtain a temperature value to be measured. The signal processing circuit has different processing methods for different types of temperature measuring resistors. When the temperature measuring resistor is a thermistor, the relationship between the thermistor and the temperature is as follows:
Wherein B is the material constant of the thermistor, T 25 represents 25 ℃, R t25 is the resistance of the thermistor at 25 ℃, and T is the current temperature to be measured.
Transforming the formula (4) to obtain a representation mode of the temperature to be measured:
according to the relation between the temperature measuring resistor and the temperature change signal, the thermistor is used as the temperature measuring resistor in the formula (2), and the following can be obtained:
According to the formula (6), the temperature value to be measured can be calculated according to the parameters of the thermistor, the circuit parameters of the temperature measuring device, the input sine wave signals and the temperature change signals output by the signal detection circuit.
On the basis of formulas (3) and (4), deriving the temperature value T from the temperature change signal to obtain the sensitivity of the detected temperature change signal to the temperature value to be detected, wherein the sensitivity is expressed as follows:
It is known that the sensitivity of the temperature to be measured is related to the ac excitation signal (sine wave signal), the circuit parameters of the device, and the parameters of the temperature measuring resistor, and is positively correlated with the resistor R 1, the excitation signal, and the coil number N 1、Np, and the sensitivity of the temperature measurement can be improved by increasing the amplitude of the ac excitation signal and the resistance value of the resistor R 1.
When the temperature measuring resistor is a platinum resistor, the relation between the platinum resistor and the temperature is as follows:
Rt＝(α·T+1)R0 (8)
Wherein alpha is the temperature drift coefficient of the platinum resistor, and the unit is ppm/DEG C; t is the temperature to be measured, and R 0 is the resistance of the platinum resistor at 0 ℃.
Transforming the formula (8) to obtain a representation mode of the temperature to be measured:
according to the relation between the temperature measuring resistance and the temperature change signal, the platinum resistance is used as the temperature measuring resistance in the formula (2), and the following can be obtained:
On the basis of formulas (3) and (8), deriving the temperature change signal from the temperature value T to obtain the sensitivity of the detected temperature change signal to the measured temperature value, wherein the sensitivity is expressed as follows:
It can be seen that the sensitivity of the temperature to be measured is related to the excitation signal, the circuit parameters of the device, and the parameters of the temperature measuring resistor, and is positively related to the resistor R 1, the excitation signal, and the coil number N 1、Np, and the sensitivity of the temperature measurement can be improved by increasing the amplitude of the excitation signal and the resistance value of the resistor R 1.
As shown in fig. 1, the high-precision temperature measurement device of the embodiment further comprises an analog-to-digital conversion circuit and a bridge supply alternating voltage signal acquisition circuit;
The bridge supply alternating current voltage signal acquisition circuit is used for acquiring voltage signals of a first coil of a secondary side of the first transformer;
the analog-to-digital conversion circuit is used for converting the temperature change signal into a digital temperature change signal; and converting the voltage signal to a digital voltage signal;
the signal processing circuit processes the temperature change signal to obtain a temperature value, and the signal processing circuit comprises:
Performing discrete Fourier transform on the digital temperature change signal to obtain the amplitude of the digital temperature change signal;
performing discrete Fourier transform on the digital voltage signal to obtain the amplitude of the digital voltage signal;
And calculating to obtain a temperature value according to the type of the temperature measuring resistor, the circuit parameter, the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal.
In this embodiment, the analog temperature change signal detected by the signal detection circuit is subjected to analog-to-digital conversion by the analog-to-digital conversion circuit to obtain a digital temperature change signal, and the voltage signal on the first coil N 1 of the secondary of the first transformer is collected by the bridge supply alternating current voltage signal collection circuit, and is subjected to analog-to-digital conversion by the analog-to-digital conversion circuit to obtain a digital voltage signal; the signal processing circuit performs discrete Fourier transform on the digital temperature change signal to obtain the amplitude of the digital temperature change signal, and performs discrete Fourier transform on the digital voltage signal to obtain the amplitude of the digital voltage signal.
In some embodiments, for a sine wave signal, the data for the time window of t 2 seconds is truncated at intervals of t 1 seconds, and the time windows overlap for t 2-t1 seconds. Let the data length of the t 2 second time window be N a, the digital sine wave signal sequence be x (N), and calculate its amplitude by discrete fourier transform as shown in equation (12):
Setting the frequency of the sine wave signal as f B, the sampling frequency of the digital signal as f s, when In this case, X (k) is a complex value corresponding to a sine wave signal having a frequency f B.
In order to reduce the influence of the fluctuation of the excitation signal, the temperature change signal detected by the signal detection circuit and the voltage signal U N1 on the first coil N 1 of the first transformer are synchronously acquired (wherein,) And respectively converting the digital temperature change signal and the digital voltage signal into corresponding digital temperature change signals and digital voltage signals, and calculating the amplitude V o of the digital temperature change signals and the amplitude V N1 of the digital voltage signals according to the method for calculating the amplitude by discrete Fourier transformation to obtain V o/VN1, namely/>Is a value of (2); based on the calculated V o/VN1, according to the type of the temperature measuring resistor, according to the formula (6) or (10), the measured temperature value T is further calculated. That is, for the thermistor, substituting the calculated V o/VN1 into the formula (6), and calculating to obtain a temperature value; and substituting the calculated V o/VN1 into the formula (10) for the platinum resistance, and calculating to obtain a temperature value.
For example, the frequency f B of the sine wave signal is 180Hz and the sampling rate f s is 500Hz. And intercepting the data segments according to the time interval of 0.2 seconds for the acquired digital voltage signal on the secondary winding N 1 of the first transformer, and carrying out windowing processing and discrete Fourier transformation on the intercepted data segments. The truncated data time window is 2 seconds, and then the length of one truncated data is 1000, and the adjacent data time windows overlap for 1.8 seconds. According to (12),The complex amplitude of the digital voltage signal with the frequency of 180Hz is obtained as follows:
in the same way, the complex amplitude X o of the digital temperature change signal is calculated (360). Thereafter, V o/VN1 was calculated to give:
in some embodiments, the balance of the temperature bridge directly affects the temperature measurement accuracy, and in order to improve the resolution of the temperature measurement device, it is necessary to ensure that the temperature bridge remains operating near the balance state. Because of different application scenes, the temperature ranges to be measured are different, different reference resistors and/or connected coil taps are required to be set in order to ensure that different temperature measurement ranges are kept in good balance states, and the temperature measurement precision of the corresponding temperature measurement ranges is realized by adjusting the corresponding reference resistors and/or connected coil taps.
In some embodiments, the temperature measuring bridge includes at least one set of reference resistors switchable by a switch, where the resistance values of the reference resistors are different. The temperature measuring bridge comprises an inductor formed by two windings of a secondary coil of the first transformer T 1, a temperature measuring resistor and at least one group of reference resistors which can be switched on by a switch circuit, wherein one group of reference resistors are switched on by the switch circuit to form a corresponding temperature measuring bridge according to the temperature range to be measured, and the temperature measuring bridge can keep a good balance state in the current temperature range and ensure the temperature measuring resolution of the current temperature range. The reference resistors of each group are formed by resistors with various resistance values in series and/or parallel connection, and the resistance values of the reference resistors of each group are different.
In other modes, at least two groups of coil windings and corresponding taps are arranged on the secondary side of the first transformer, and corresponding temperature measuring bridges are formed by connecting different taps according to the temperature range to be measured, so that the temperature measuring bridges can keep a good balance state in the current temperature range, and the temperature measuring resolution of the current temperature range is ensured.
The temperature measuring bridge comprises a temperature measuring resistor and at least one group of reference resistors switched on by a switch, at least two groups of coil windings and corresponding taps are arranged on the secondary side of the first transformer, and in different temperature measuring ranges, the temperature measuring bridge is ensured to be maintained near a balanced state by switching on the corresponding reference resistors and connecting the corresponding taps, so that the temperature measuring resolution is improved.
For example, as shown in fig. 4, three sets of coil windings and taps corresponding to the windings are disposed on the secondary side of the first transformer of the temperature measuring bridge, and the three sets of coil windings are 40, 24, and 24 turns, respectively, and can be selectively connected to the first tap or the second tap through the switch S1. Meanwhile, 12 groups of reference resistors with different resistance values are arranged, the resistance value ranges of the reference resistors are R 6+R8//R22 to R 6+R8//R33 (the resistance values of R 22 to R 33 are gradually increased), the temperature measurement range of each group of reference resistors is 1-2 ℃, in a specific mode, the resistance value range of the reference resistor is 1.61KΩ -4.13 KΩ, one group of reference resistors can be selected by switching the switch S2 and the switch S3 (in order to improve the stability and the reliability of the device, a double-connected switch consisting of the switch S2 and the switch S3 can be used, and other switch forms can be used when the device is implemented). By arranging a plurality of groups of coil windings and a plurality of groups of reference resistors, high-precision temperature measurement within a temperature measurement range of 1-40 ℃ can be realized.
When the NTC thermistor with the resistance value of 3KΩ is selected as a temperature measuring resistor at normal temperature, the signal processing circuit is connected with the first end through the switch control circuit control switch S1 in the temperature measuring range of 0-20 ℃ so as to enable the temperature measuring bridge to be connected with the first tap, at the moment, the first coil N 1 is 64 circles, the second coil N 2 is 24 circles, and then a proper group of reference resistors in 12 groups are selected through the duplex switches S2 and S3, so that the temperature measuring bridge can reach the temperature measuring precision in the temperature measuring range of 0-20 ℃.
In the temperature measuring range of 20-40 ℃, the signal processing circuit is connected with the second end through the switch control circuit control switch S1, so that the temperature measuring bridge is connected with the second tap, at the moment, the first coil N 1 is 24 circles, the second coil N 2 is 24 circles, and then the proper reference resistor is selected through the duplex switches S2 and S3, so that the temperature measuring bridge can reach the temperature measuring precision in the temperature measuring range of 20-40 ℃.
In some embodiments, the sine wave signal of the first transformer may be provided by a signal generator, and may be generated by an oscillating circuit, or may be generated by providing a digital-to-analog conversion circuit and a signal amplifier, as shown in fig. 3, after generating a digital signal by a signal processing circuit, converting the digital signal by the digital-to-analog conversion circuit, and amplifying the digital signal by the signal amplifier.
The high-precision temperature measuring device provided by the embodiment of the application adopts the circuit design that the alternating current excitation signal drives the temperature measuring bridge to measure the temperature, can overcome the influence of 1/f noise of a device, and can avoid that the noise of a direct current voltage signal is superposed on a temperature change signal of measurement output compared with a direct current driving mode; the device uses fewer resistance components, adopts an LR alternating current bridge to realize temperature measurement and adopts a current coupling amplification mode, and can effectively reduce the influence of resistance thermal noise on a measurement result; the frequency domain method based on discrete Fourier transform is adopted to process the temperature change signal, so that the accuracy of a temperature measurement result can be improved; the plurality of groups of coil windings and/or reference resistors are arranged, so that the balance degree of the temperature measuring bridge can be ensured in different temperature measuring ranges, and the temperature measuring resolution is improved. The temperature measuring device provided by the application can reach the measurement resolution of 5 mu K level in the frequency band of 1 mHz-0.1 Hz, and can meet the temperature measurement requirements in high-precision temperature measurement scenes such as seismic observation, gravitational wave detection and the like.
The embodiment of the application also provides a high-precision temperature measurement system which comprises at least one group of high-precision temperature measurement devices. As shown in fig. 5, according to a specific application scenario, multiple groups of high-precision temperature measurement devices of the high-precision temperature measurement system can be utilized to perform temperature measurement on different measuring points. For each group of high-precision temperature measuring devices in the system, a respective transformer can be used for providing sine wave signals, the same transformer can be used for providing sine wave signals, respective analog-to-digital conversion circuits can be used for converting temperature change signals in each path of analog form, respective signal processing circuits can be used for converting temperature change signals in each path of analog form, the same signal processing circuit can be used for uniformly processing temperature change signals in each path of temperature change signals to obtain temperature values measured by each device, the system structure can be flexibly configured according to application scenes and temperature measurement requirements, and specific structural forms are not limited.
Those of ordinary skill in the art will appreciate that: the discussion of any of the embodiments above is merely exemplary and is not intended to suggest that the scope of the disclosure, including the claims, is limited to these examples; the technical features of the above embodiments or in the different embodiments may also be combined under the idea of the present disclosure, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in details for the sake of brevity.
Additionally, well-known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown within the provided figures, in order to simplify the illustration and discussion, and so as not to obscure the embodiments of the present application. Furthermore, the devices may be shown in block diagram form in order to avoid obscuring the embodiments of the present application, and also in view of the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the embodiments of the present application are to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that embodiments of the application can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.
While the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of those embodiments will be apparent to those skilled in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.
The present embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Accordingly, any omissions, modifications, equivalents, improvements, and the like, which are within the spirit and principles of the embodiments of the application, are intended to be included within the scope of the present disclosure.
Claims (10)
1. A high accuracy temperature measurement device, comprising: the temperature measuring device comprises a first transformer, a temperature measuring bridge, a second transformer, a signal detection circuit and a signal processing circuit; the secondary output end of the second transformer is connected with the signal input end of the signal detection circuit;
The temperature measuring bridge is used for outputting a current signal for reflecting temperature change when the resistance value of the temperature measuring resistor changes along with the temperature change and the temperature measuring bridge deviates from a balance state after the sine wave signal is input to the primary side of the first transformer;
The signal detection circuit is used for processing the current signal to obtain a temperature change signal;
the signal processing circuit is used for processing the temperature change signal to obtain a temperature value.
2. The apparatus of claim 1, wherein the signal detection circuit processes the current signal to obtain a temperature change signal, expressed as:
Wherein N is the number of turns of the primary coil of the first transformer, U m is a sine wave signal, N 1、N2 is the number of turns of the secondary coil of the first transformer, N p is the number of turns of the primary coil of the second transformer, N s is the number of turns of the secondary coil of the second transformer, R t is the resistance of the temperature measuring resistor, R r is the resistance of the reference resistor, and R 1 is the resistance of the resistor connected between the input end and the output end of the signal detection circuit.
3. The apparatus of claim 2, wherein the temperature sensing resistor is a thermistor, and the signal processing circuit processes the temperature change signal to obtain a temperature value, expressed as:
Wherein B is the material constant of the thermistor, T 25 represents 25 ℃, and R t25 is the resistance value of the thermistor at 25 ℃.
4. The apparatus of claim 2, wherein the temperature sensing resistor is a platinum resistor, and the signal processing circuit processes the temperature change signal to obtain a temperature value, expressed as:
Wherein, alpha is the temperature drift coefficient of the platinum resistor, and R 0 is the resistance value of the platinum resistor at the temperature of 0 ℃.
5. The apparatus of claim 3 or 4, further comprising an analog-to-digital conversion circuit and a supply bridge ac voltage signal acquisition circuit;
The bridge supply alternating current voltage signal acquisition circuit is used for acquiring voltage signals of a first coil of a secondary side of the first transformer;
The analog-to-digital conversion circuit is used for converting the temperature change signal into a digital temperature change signal; and converting the voltage signal to a digital voltage signal;
the signal processing circuit processes the temperature change signal to obtain a temperature value, and the signal processing circuit comprises:
performing discrete Fourier transform on the digital temperature change signal to obtain the amplitude of the digital temperature change signal;
Performing discrete Fourier transform on the digital voltage signal to obtain the amplitude of the digital voltage signal;
and calculating to obtain a temperature value according to the type of the temperature measuring resistor, the circuit parameter, the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal.
6. The apparatus of claim 5, wherein calculating a temperature value based on the type of temperature sensing resistor, a circuit parameter, the magnitude of the digital temperature change signal, and the magnitude of the digital voltage signal comprises:
and calculating to obtain a temperature value according to the type of the temperature measuring resistor, the circuit parameter, the ratio between the amplitude of the digital temperature change signal and the amplitude of the digital voltage signal.
7. The apparatus of claim 1, wherein the thermometric bridge comprises at least one set of reference resistors switchable by a switch, each set of reference resistors having a different resistance value.
8. The apparatus of claim 1 or 7, wherein the secondary of the first transformer is provided with at least two sets of coil windings and corresponding taps.
9. The apparatus of claim 1, wherein the signal detection circuit comprises a current-to-voltage conversion circuit consisting of a first amplifier, a resistor R 1、R2, and a capacitor C 1, an integration circuit consisting of a second amplifier, a resistor R 3, and a capacitor C 2, and a resistive attenuation network consisting of resistors R 4 and R 5; one end of a secondary coil of the second transformer is connected with the reverse input end of the first amplifier, and the other end of the secondary coil of the second transformer is grounded; the first end of the resistor R 1 and the first end of the capacitor C 1 are connected with the reverse input end of the first amplifier, the output end of the first amplifier is connected with the second end of the capacitor C 1 and the first end of the resistor R 2, and the second end of the resistor R 1 is connected with the second end of the resistor R 2 to form the output end of the signal detection circuit; the output end of the signal detection circuit is connected with the reverse input end of the second amplifier through a resistor R 3, the reverse input end of the second amplifier is connected with the output end of the second amplifier through a capacitor C 2, the positive input end of the second amplifier is grounded, and the output end of the second amplifier is connected with the positive input end of the first amplifier through a resistor attenuation network.
10. A high accuracy temperature measurement system comprising at least one set of high accuracy temperature measurement devices according to any one of claims 1-4.
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