A temperature measurement device with expandable range based on multiplexing of multi-channel reference resistors

Abstract

The present application discloses a range-expandable temperature measurement device based on multiplexing of multi-channel reference resistors, including a temperature measurement bridge module, a processing module and an intelligent control module, wherein the temperature measurement bridge module includes an AC carrier source, a parallel Wheatstone bridge and a multiplexing selector, the parallel Wheatstone bridge includes a first bridge arm and a second bridge arm in parallel, the first bridge arm is composed of a first fixed resistor and a plurality of parallel reference resistors in series, each reference resistor is connected in series with a switch in the multiplexing selector, and the second bridge arm is composed of a second fixed resistor and a thermistor in series. The present application switches different reference resistors at the temperature measurement bridge through a switch to switch different operating points, which can reduce the temperature measurement range of a single operating point, thereby achieving the effect of reducing the influence of subsequent circuit gain errors, and combining multiple operating points to work, which can expand the range without affecting the temperature measurement resolution, while meeting the requirements of temperature measurement range and measurement accuracy.

Description

Technical Field

[0001] The present application belongs to the field of precision measurement, and more specifically, relates to a temperature measurement device with an expandable range based on multiplexing of multiple reference resistors. Background Art

[0002] Space-based gravitational wave detection primarily detects gravitational wave signals in the millihertz frequency band. Its core scientific payloads, including space inertial sensors and intersatellite laser interferometry ranging systems, have extremely high performance requirements, necessitating the control of various noise sources, of which temperature noise is a significant one. In space-based gravitational wave detection, the temperature of sensitive structures in the core payload must be measured and controlled at the μK level. Furthermore, due to the complex structure of space-based gravitational wave detection spacecraft, the operating temperatures of different scientific payload components vary significantly, placing high demands on temperature sensors with a wide dynamic range.

[0003] Existing high-precision temperature measurement devices suitable for space exploration use Wheatstone bridges based on negative temperature coefficient thermistors. If a temperature measurement system with a resolution of μK is to be designed, its temperature measurement dynamic range is usually less than 1°C, which cannot meet the technical requirements of large dynamic range, different operating temperature points and intelligent control on orbit. Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a range-scalable temperature measurement device based on multi-channel reference resistor multiplexing, aiming to solve the problem that traditional high-precision temperature measurement devices cannot simultaneously meet the requirements of temperature measurement range and measurement accuracy.

[0005] To achieve the above objectives, the present application provides a temperature measurement device with an expandable range based on multiplexing of multiple reference resistors, comprising:

[0006] A temperature measurement bridge module includes an AC carrier source, a parallel Wheatstone bridge, and a multiplexer selector. The parallel Wheatstone bridge includes a first bridge arm and a second bridge arm connected in parallel. The first bridge arm is composed of a first fixed resistor and a plurality of parallel reference resistors connected in series. Each reference resistor is connected in series with a switch in the multiplexer selector. The second bridge arm is composed of a second fixed resistor and a thermistor connected in series. The multiplexer selector is used to switch the corresponding reference resistors by controlling the on and off of each switch according to an input switch switching control signal, thereby achieving temperature measurement at different temperature measurement equilibrium working points, thereby achieving expansion of the entire temperature measurement range. The parallel Wheatstone bridge is used to detect the change in resistance of the thermistor caused by the temperature signal. The AC carrier source is used to modulate the temperature signal onto the AC carrier and output a differential voltage signal containing the temperature signal.

[0007] a processing module, configured to process the differential voltage signal and output a voltage signal reflecting a temperature signal;

[0008] The intelligent control module is used to determine whether the temperature measurement balance working point needs to be adjusted based on the voltage signal received in real time. If so, it outputs the corresponding switch switching control signal; otherwise, it maintains the current temperature measurement balance working point and continues to output; then, based on the currently selected reference resistance and the voltage signal, it selects the corresponding temperature and voltage function relationship, converts the collected voltage signal into temperature data, and outputs it.

[0009] The range-scalable temperature measurement device based on multiple reference resistor multiplexing provided by the present application can narrow the temperature measurement range of a single working point by switching different reference resistors at the temperature measurement bridge, thereby switching different working points, thereby reducing the influence of subsequent circuit gain errors. By combining multiple working points, the range can be expanded without affecting the temperature measurement resolution, while meeting the requirements of temperature measurement range and measurement accuracy. In addition, the use of an intelligent control module can realize accurate measurement and data collection of the temperatures of multiple working points, and realize intelligent adjustment, effectively improving the flexibility and stability of the device, and providing a reliable temperature monitoring solution for various application scenarios.

[0010] As a further preferred embodiment, the processing module is used to amplify, phase-sensitively demodulate, low-pass filter and analog-to-digital convert the differential voltage signal, and then output a voltage signal reflecting the temperature signal.

[0011] As further preferred, the processing module includes:

[0012] A differential instrumentation amplifier, configured to amplify the differential voltage signal and output the amplified signal;

[0013] The switch-type phase-sensitive demodulator includes an analog switch and an operational amplifier, and is used to perform phase-sensitive demodulation and differential amplification on the amplified signal output by the differential instrumentation amplifier, and then output a voltage signal reflecting the temperature signal, thereby completing the demodulation of the AC carrier.

[0014] Low-pass filter, used to filter out interference signals in voltage signals;

[0015] The analog-to-digital converter is used to convert the signal output by the low-pass filter into digital form and output it.

[0016] As further preferred, the AC carrier source includes:

[0017] A reference source, used to generate an output DC signal;

[0018] A proportional amplifier, using an operational amplifier and a fixed resistor, is used to provide the required gain for the DC signal and generate an amplitude signal required by the AC carrier;

[0019] Crystal oscillator, used to generate the frequency signal required by the AC carrier;

[0020] The analog switch is used to output an AC carrier according to the amplitude signal and the frequency signal.

[0021] As a further preferred embodiment, in the parallel Wheatstone bridge, the resistance of the reference resistor is related to the parameter characteristics of the thermistor itself;

[0022] After determining the temperature measurement range, the entire temperature measurement range is divided into several temperature measurement segments, and the middle temperature point of the temperature measurement segment is selected as the temperature measurement equilibrium working point. Then, the resistance value of each reference resistor is determined based on the resistance value of the thermistor at each temperature measurement equilibrium working point temperature.

[0023] As a further preferred method, the intelligent control module determines whether it is necessary to adjust the temperature measurement balance working point:

[0024] The voltage signal is calculated based on the relationship between the input temperature and the output voltage in the temperature measuring device to obtain the input temperature of the temperature measuring device. When the temperature is higher than the maximum value of the temperature measurement section corresponding to the currently selected reference resistor, the multiplexer selector is used to control the on and off of the corresponding switch to switch to the reference resistor with a higher temperature measurement balance point. When the temperature is lower than the minimum value of the temperature measurement section corresponding to the currently selected reference resistor, the multiplexer selector is used to control the on and off of the corresponding switch to switch to the reference resistor with a lower temperature measurement balance point. When the temperature is within the temperature measurement section corresponding to the currently selected reference resistor, the current temperature measurement balance working point is maintained and output is continued.

[0025] As a further preferred method, the method for determining the functional relationship between temperature and voltage is:

[0026] Before temperature measurement, the temperature measuring devices for each reference resistor switching are calibrated separately, a constant temperature box is selected to apply a temperature step signal, and the voltage signal output by the processing module is measured; then a thermometer is used for synchronous acquisition, and finally, through data fitting, the functional relationship between the temperature and voltage corresponding to the switching of each reference resistor is obtained.

[0027] As a further preference, the temperature measuring device is applicable to spaceborne technology, and is used to measure the temperature of a core payload sensitive structure in space gravitational wave detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a principle block diagram of a range-scalable temperature measurement device based on multiple reference resistor multiplexing provided by the present application;

[0029] Figure 2 This is a working diagram of the intelligent control module provided in an embodiment of the present application;

[0030] Figure 3 This is a schematic diagram of the specific division of the temperature measurement range in the range expansion provided in the embodiment of the present application;

[0031] Figure 4 This is a flow chart of step 1 in the intelligent control module provided in an embodiment of the present application;

[0032] Figure 5 This is a flow chart of step 2 in the intelligent control module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0034] It should be understood that, in the description of this application, the term "several" means at least one, such as one, two, etc., unless otherwise clearly and specifically defined; the term "plurality" means two or more, unless otherwise clearly and specifically defined; the terms "first" and "second" etc. are used to distinguish different objects, rather than to describe a specific order of objects; the term "and / or" includes any and all combinations of one or more related listed items.

[0035] Additionally, references throughout this specification to "one embodiment," "one embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment," "in one embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0036] In order to solve the problem of contradiction between temperature measurement range and accuracy of traditional high-precision temperature measurement devices, the present application provides a range-scalable temperature measurement device based on multi-channel reference resistor multiplexing. The device can be used in all scenarios requiring high-precision and large dynamic range temperature measurement, such as in spaceborne technology, for measuring the temperature of sensitive structures of core payloads in space gravitational wave detection. For high-precision temperature measurement in the low-frequency band, a multi-working point combination design is adopted to solve the problem of high-precision and large-range compatibility requirements.

[0037] Specifically, the temperature measurement device provided in this application switches multiple working points in combination through switches, and expands the measuring range to meet the requirements of temperature measurement range and temperature measurement accuracy; in addition, the device is based on a parallel Wheatstone bridge temperature measurement structure, combined with an intelligent control module, which can realize accurate measurement and data collection of multiple working point temperatures.

[0038] Figure 1 This is a principle block diagram of a temperature measurement device with an expandable range based on multiple reference resistors provided by the present application. Figure 1 As shown, the temperature measurement device mainly includes a temperature measurement bridge module, a processing module and an intelligent control module.

[0039] The temperature measurement bridge module includes an AC carrier source, a parallel Wheatstone bridge and a multiplexer.

[0040] The parallel Wheatstone bridge includes two parallel bridge arms, one of which (e.g. Figure 1 The right side of the bridge consists of a fixed resistor R2 and a thermistor R TS(T) The other bridge arm (such as Figure 1 The left side of the bridge consists of a fixed resistor R1 and several reference resistors R in parallel. ref1 ~R refx The reference resistors R ref1 ~R refx Corresponding to switches S1 to S2 in the multiplexer x Series connection.

[0041] In this application, the multiplexer selector is used to control the on and off of each switch to switch the reference resistor according to the switch switching control signal input by the back-end intelligent control module, complete the switching of different temperature measurement ranges, and thus realize temperature measurement of different temperature measurement balance working points.

[0042] A parallel Wheatstone bridge is used to detect changes in thermistor resistance caused by ambient temperature (temperature signal). An AC carrier source modulates the low-frequency temperature signal onto a high-frequency AC carrier, outputting a differential voltage signal containing the temperature signal. The differential voltage signal is the voltage output from the positive and negative output terminals of the parallel Wheatstone bridge. The positive output terminal is the terminal connected to the thermistor by fixed resistor R2, while the negative output terminal is the terminal connected to a reference resistor or switch by fixed resistor R1.

[0043] This application uses AC carrier modulation technology and applies it to a parallel Wheatstone bridge. In order to improve the temperature measurement resolution of the circuit, the left side of the bridge is composed of multiple reference resistors. The multi-working point combination is completed by switching, which can expand the entire temperature measurement range.

[0044] It is understood that the present application switches between different reference resistors at the temperature measurement bridge to achieve different temperature measurement equilibrium operating points. The resistance value of each reference resistor can be set accordingly based on the temperature measurement requirements. Specifically, the required temperature measurement range can be divided into several temperature measurement segments, and the middle value of each temperature measurement segment is taken as the temperature measurement equilibrium operating point. The resistance value of each reference resistor is then determined by combining the resistance value of the thermistor at each temperature measurement equilibrium operating point.

[0045] The processing module is used to process the differential voltage signal output by the temperature measurement bridge module, specifically by amplification, phase-sensitive demodulation, low-pass filtering and analog-to-digital conversion, and then output a voltage signal reflecting the temperature signal.

[0046] The intelligent control module is used to determine whether the temperature measurement balance working point needs to be adjusted based on the voltage signal received in real time. If so, the corresponding switch switching control signal is output to the multiplexer selector. Otherwise, the current temperature measurement balance working point is maintained and the output is continued. Then, based on the currently selected reference resistance and the voltage signal, the corresponding temperature-voltage function relationship is selected, and the collected voltage signal is converted into temperature data and output.

[0047] Specifically, the method for determining whether the temperature measurement balance working point needs to be adjusted can be: the voltage signal output by the processing module is calculated through the relationship between the input temperature and the output voltage in the temperature measuring device to obtain the input temperature of the temperature measuring device; when the temperature is higher than the maximum value of the temperature measurement segment corresponding to the currently selected reference resistor, the on-off of the corresponding switch is controlled by the multiplexing selector to switch to the reference resistor with a higher temperature measurement balance point; when the temperature is lower than the minimum value of the temperature measurement segment corresponding to the currently selected reference resistor, the on-off of the corresponding switch is controlled by the multiplexing selector to switch to the reference resistor with a lower temperature measurement balance point; when the temperature is within the temperature measurement segment corresponding to the currently selected reference resistor, the current temperature measurement balance working point is maintained and continued to be output.

[0048] The method for determining the functional relationship between temperature and voltage can be: before temperature measurement, the temperature measuring device when each reference resistor is switched is calibrated separately, a constant temperature box is selected to apply a temperature step signal, and the voltage signal output by the processing module is measured; then a thermometer is used for synchronous acquisition, and finally, through data fitting, the functional relationship between temperature and voltage corresponding to the switching of each reference resistor is obtained.

[0049] The range-scalable temperature measurement device based on multiple reference resistor multiplexing provided by the present application can narrow the single temperature measurement range by switching different reference resistors at the temperature measurement bridge and thus switching different operating points, thereby reducing the influence of subsequent circuit gain errors. Combining multiple operating points can expand the range without affecting the temperature measurement resolution, while meeting the temperature measurement range and measurement accuracy requirements. In addition, the use of an intelligent control module can realize accurate measurement and data collection of the temperatures of multiple operating points, and realize intelligent adjustment, effectively improving the flexibility and stability of the device, and providing a reliable temperature monitoring solution for various application scenarios.

[0050] The temperature measurement device provided in this application is described below with reference to specific embodiments.

[0051] This embodiment provides a range-scalable temperature measurement device based on multiplexed reference resistors. This device aims to address the challenges of wide temperature measurement ranges and high precision requirements at critical loads. By switching multiple operating points, the range is expanded to meet both measurement range and accuracy requirements. This device, based on a parallel Wheatstone bridge temperature measurement structure and combined with an intelligent control module, enables accurate temperature measurement and data collection at multiple operating points.

[0052] Specifically, by switching different reference resistors at the temperature measurement bridge and thus switching different operating points, the single temperature measurement range can be narrowed, thereby reducing the impact of subsequent circuit gain errors. Combining multiple operating points can expand the measurement range without affecting the temperature measurement resolution.

[0053] like Figure 1 As shown in FIG, the temperature measurement device mainly includes the following parts: a temperature measurement bridge module, a processing module (a differential instrumentation amplifier IA, a switching phase-sensitive demodulator, a low-pass filter, and an analog-to-digital converter), and an intelligent control module.

[0054] In the temperature measurement bridge module, the parallel Wheatstone bridge is powered by an AC carrier source, and the AC carrier signal generated by the AC carrier source is applied to the parallel Wheatstone bridge, and the AC carrier is modulated on the difference in the ratio of the two resistances of the bridge caused by the temperature signal. ref1 ~R refx In the example, each reference resistor is connected to a switch. These switches S1 to S x It consists of a multiplexer selector whose output is controlled by digital signals. Different combinations of input digital signals form different channel selections, select corresponding reference resistors, and realize temperature measurement of different equilibrium operating points.

[0055] The multiplexer selector controls the on and off of each internal switch according to the input logic control signal, selects different reference resistors, and completes the switching of the bridge operating point.

[0056] The fixed resistors on the left and right are connected to the negative and positive inputs of a differential instrumentation amplifier, respectively. After differential amplification, the output is fed to a switching phase-sensitive demodulator, generating a voltage signal reflecting the temperature signal. To avoid high-frequency signal interference, a low-pass filter is designed for signal processing to ensure the stability of the output signal. The temperature signal is accurately collected and recorded through an analog-to-digital converter. The collected temperature output is fed back to the intelligent control module, where an intelligent algorithm determines the gear position. The intelligent control module determines the digital signal output of the multiplexer selector, thereby switching the reference resistor. This allows the device to switch to different temperature measurement equilibrium operating points as needed, thereby covering a wider temperature measurement range.

[0057] This embodiment uses a thermistor as the temperature sensing component, or temperature probe. Due to the nature of the thermistor, its resistance exhibits a nonlinear relationship with the ambient temperature. A parallel Wheatstone bridge with an AC carrier is used at the front end of the circuit to detect the differential output voltage of the bridge caused by the thermistor's resistance change, thereby converting the temperature signal into an electrical signal.

[0058] As an embodiment of the present application, a thermistor with a negative temperature coefficient (NTC) is selected, and the relationship between its resistance and temperature is as follows:

[0059]

[0060] In formula (1), in this embodiment, the nominal resistance value R0 is selected as 10KΩ, the value of β is 3500K, T0 is 293K, and T is the ambient temperature.

[0061] The AC carrier source is used to generate a square wave signal, including through a reference source, a proportional amplifier, a crystal oscillator and an analog switch.

[0062] Among them, the crystal oscillator is used to generate the frequency signal required by the AC carrier; the reference source is used to output the DC signal; the operational amplifier and the fixed resistor are combined to form a proportional amplifier, which is used to provide the required gain for the DC signal output by the reference source and generate the amplitude signal required by the AC carrier; the analog switch outputs a square wave signal according to the frequency signal and the amplitude signal, that is, the AC carrier signal.

[0063] Specifically, the reference source provided in this embodiment can adopt a high-precision, low-noise voltage source to ensure that the output DC signal has a stable amplitude; the operational amplifier can adopt a low-noise type operational amplifier to maintain the accuracy and stability of the signal, ensuring that the accuracy of the reference source signal remains unchanged after passing through the operational amplifier; the fixed-value resistor adopts a precision low-temperature drift resistor, which has a stable resistance value and low temperature drift properties, and can ensure the accuracy and stability of the output signal;

[0064] Furthermore, the frequency of the AC carrier source provided in this embodiment can be selected based on the low-frequency noise characteristics of the back-end differential instrumentation amplifier, and preferably uses a frequency greater than the noise corner frequency of the differential instrumentation amplifier, that is, a frequency higher than the 1 / f inflection point of the differential instrumentation amplifier.

[0065] The AC carrier source provided in this embodiment, through the combination of these components, can achieve a high-precision, low-noise square wave signal output, which serves as the AC carrier signal and provides a stable and accurate excitation signal for the temperature measurement bridge. The design and selection of these components are crucial to the performance and accuracy of the entire device.

[0066] The temperature measuring probe, i.e. thermistor, adopts a two-wire system and is connected to the location where the temperature signal needs to be measured through leads.

[0067] The reference resistor in the temperature measurement bridge module can have multiple different values ​​according to the temperature measurement requirements. The reference resistor must meet the characteristics of high precision and low temperature coefficient.

[0068] Fixed resistors in the temperature bridge module: Fixed resistors are stable resistors whose resistance value remains constant within a certain range. To ensure resistance stability, high-precision resistors with a small tolerance and low temperature coefficient are required. In this example, a high-precision resistor with a temperature coefficient of 0.5 ppm / K and a resistance of 10 kΩ is selected.

[0069] The differential instrumentation amplifier is used to amplify the differential voltage signal output by the temperature measurement bridge module, which helps to suppress common-mode interference, enhance signal strength, and improve the signal-to-noise ratio.

[0070] A switched-mode phase-sensitive demodulator can utilize an analog switch, a low-noise operational amplifier, and precision, low-drift resistors. The analog switch is used to phase-sensitively demodulate the output signal of the differential instrumentation amplifier and output it. The low-noise operational amplifier and precision, low-drift resistor form a differential amplifier that amplifies the analog switch output signal and outputs a voltage signal reflecting the temperature signal, thereby demodulating the AC carrier. The switched-mode phase-sensitive demodulator provided in this embodiment utilizes a low-noise operational amplifier and precision, low-drift resistors, resulting in excellent low-frequency performance. This effectively suppresses low-frequency 1 / f noise and improves signal accuracy.

[0071] The demodulated voltage signal passes through a low-pass filter to remove the residual high-frequency (carrier frequency and its multiples) interference and retain the low-frequency range required for temperature measurement.

[0072] The low-pass filter is used to avoid high-frequency signal interference in the temperature measurement circuit. It is composed of a low-noise instrument amplifier and high-precision resistors and capacitors.

[0073] The demodulated voltage signal is low-pass filtered to output a voltage, which is converted into a digital signal by an analog-to-digital converter (ADC) to output a voltage signal reflecting the temperature signal.

[0074] The intelligent control module may adopt a field programmable gate array (FPGA) device or a digital signal processor (DSP) and the like.

[0075] like Figure 2 As shown, the intelligent control module provided in this embodiment is used to perform the following steps:

[0076] Step 1: Based on the voltage signal collected in real time, it is intelligently determined whether the working point needs to be adjusted according to the pre-stored balance point control algorithm, that is, the voltage signal collected in real time is calculated through the relationship between the input temperature and the output voltage in the temperature measuring device (see formulas (1) and (2) in the following text) to obtain the input temperature of the device. When the temperature is higher than the maximum value of the temperature measurement section corresponding to the currently selected reference resistor, the multiplexer is used to control the on and off of the corresponding switch to switch to a higher temperature measurement balance point reference resistor; when the temperature is lower than the minimum value of the temperature measurement section corresponding to the currently selected reference resistor, the multiplexer is used to control the on and off of the corresponding switch to switch to a lower temperature measurement balance point reference resistor; when the temperature is within the temperature measurement section corresponding to the currently selected reference resistor, the current temperature measurement balance working point is maintained and continues to be output;

[0077] Step 2: If Figure 5 As shown, according to the currently selected reference resistor, combined with the voltage signal through the corresponding temperature and voltage function relationship, the collected voltage signal is converted into temperature data, and then output after filtering, extraction and other processing.

[0078] Furthermore, the intelligent control module provided in this embodiment is further used to generate the timing control signal required to control the ADC device and receive the collected data signal returned by the ADC.

[0079] Taking the temperature range of 10 to 30 degrees Celsius as an example, the entire range is divided into 10 gears. The relationship curve between thermistor resistance and temperature can be used to obtain the values ​​of ten reference resistors. Considering the high accuracy requirements of the sensor, the reference resistor of a specific resistance value needs to have a low temperature coefficient and high precision. After determining the value of the reference resistor, combined with formula (1), the temperature measurement device inputs temperature T and outputs voltage Vo The relationship is:

[0080]

[0081] In formula (2), V ref is the AC carrier amplitude, G IA is the gain of the differential instrumentation amplifier, G DE is the gain of the switching phase-sensitive demodulator, G LPF is the gain of the low-pass filter, R TS is the resistance of the thermistor, R refi is the resistance value of the currently selected reference resistor.

[0082] After designing the circuit parameters, the output curve of the circuit under different reference resistances can be obtained, and the temperature can be specifically divided, such as Figure 3 As shown, the entire temperature measurement requirement is met. The following principles should be considered when selecting the temperature measurement range: first, the entire temperature measurement range must be met and a certain degree of overlap between the various gears must be achieved; second, the output voltage of each gear must be near zero and as symmetrical as possible to reduce the influence of the AC carrier; and third, the overall limiting output must be controlled.

[0083] After determining the reference resistors, combined with the output curve of the circuit, an intelligent control module is required to combine the various temperature measurement ranges to complete the range expansion.

[0084] The intelligent control module is used to intelligently determine whether the working point needs to be adjusted based on the voltage signal collected in real time. After determining the temperature measurement range of the ten gears, the output range corresponding to each gear can be obtained. Since the temperature and voltage output correspond one to one, the temperature range can be divided. The output results of this embodiment are as follows: Figure 3 As shown; Figure 4 The working principle of the algorithm shown is mainly based on the judgment statement. According to the output voltage feedback, the current input temperature T of the device is calculated. When the current temperature T exceeds the maximum temperature range T i,max When the value is less than the set minimum range T, the multiplexer is fed back to switch to a higher gear (i+1 gear); if the value is less than the set minimum range T i,min When the temperature reaches the lower level (i-1 level), the multiplexer selector is fed back to switch to the lower level; if the temperature range is within the level design range, the original level (i-1 level) is maintained and the output is continued; the normal operation of the algorithm can ensure the connection between the various levels, while ensuring the accuracy, the temperature measurement range is expanded; the flexible switching of the temperature measurement range realizes intelligent adjustment, and improves the flexibility and stability of the device.

[0085] Before temperature measurement, the temperature measurement device for each reference resistor when it is turned on is calibrated separately. A high-precision constant temperature box is selected to apply a temperature step signal, and the overall output of the circuit is measured. A high-precision commercial thermometer is used for synchronous acquisition, and finally data fitting is performed to obtain the functional relationship between temperature and voltage within the entire dynamic range of the operating point determined by each reference resistor.

[0086] The temperature measurement device provided in this embodiment offers the advantages of high precision, high stability, and strong anti-interference capabilities, making it suitable for multi-operating-point temperature measurement scenarios. While maintaining high-precision temperature resolution, it also expands the temperature measurement range. Through the intelligent control module, it enables accurate measurement and data collection of multiple operating-point temperatures, and implements intelligent regulation, improving the device's flexibility and stability, providing a reliable temperature monitoring solution for a variety of application scenarios.

[0087] In summary, this application provides an innovative multi-operating-point temperature measurement device that combines a parallel Wheatstone bridge structure with an intelligent control module, bringing new technological breakthroughs and application prospects to the field of temperature measurement. This device not only offers high precision and stability, but also flexibility and reliability, making it suitable for temperature monitoring needs in a variety of industrial and scientific research fields.

[0088] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A temperature measurement device with an expandable range based on multiplexing of multi-channel reference resistors, characterized in that: include: A temperature measurement bridge module comprises an AC carrier source, a parallel Wheatstone bridge and a multiplexer selector, wherein the parallel Wheatstone bridge comprises a first bridge arm and a second bridge arm connected in parallel, wherein the first bridge arm is composed of a first fixed resistor and a plurality of parallel reference resistors connected in series, wherein each reference resistor is connected in series with a switch in the multiplexer selector, and the second bridge arm is composed of a second fixed resistor and a thermistor connected in series; wherein the multiplexer selector is used to switch the corresponding reference resistors by controlling the on and off of each switch according to an input switch switching control signal, thereby realizing temperature measurement of different temperature measurement equilibrium working points, and further realizing expansion of the entire temperature measurement range; the parallel Wheatstone bridge is used to detect the resistance change of the thermistor caused by the temperature signal; the AC carrier source is used to modulate the temperature signal onto the AC carrier, and output a differential voltage signal with the temperature signal; A processing module, configured to amplify, phase-sensitively demodulate, low-pass filter and perform analog-to-digital conversion on the differential voltage signal, and then output a voltage signal reflecting the temperature signal; The intelligent control module is used to determine whether the temperature measurement balance working point needs to be adjusted according to the voltage signal received in real time. If so, the corresponding switch switching control signal is output, otherwise the current temperature measurement balance working point is maintained and output is continued; then, according to the currently selected reference resistance and the voltage signal, the corresponding functional relationship between temperature and voltage is selected, and the collected voltage signal is converted into temperature data and output; The method for the intelligent control module to determine whether the temperature measurement balance working point needs to be adjusted is: The voltage signal is passed through the relationship between the input temperature and the output voltage in the temperature measuring device to calculate the input temperature of the temperature measuring device. When the temperature is higher than the maximum value of the temperature measuring section corresponding to the currently selected reference resistor, the on-off of the corresponding switch is controlled by the multiplexer selector to switch the reference resistor of a higher temperature measurement balance point; when the temperature is lower than the minimum value of the temperature measuring section corresponding to the currently selected reference resistor, the on-off of the corresponding switch is controlled by the multiplexer selector to switch the reference resistor of a lower temperature measurement balance point; when the temperature is within the temperature measuring section corresponding to the currently selected reference resistor, the current temperature measurement balance working point is maintained and outputted.

2. The range-expandable temperature measurement device based on multiplexing of multiple reference resistors according to claim 1, characterized in that: The processing module comprises: A differential instrument amplifier, used for amplifying the differential voltage signal and then outputting it; The switch-type phase-sensitive demodulator includes an analog switch and an operational amplifier, and is used to perform phase-sensitive demodulation and differential amplification processing on the amplified signal output by the differential instrumentation amplifier, and then output a voltage signal reflecting the temperature signal, thereby completing the demodulation of the AC carrier. Low-pass filter, used to filter out interference signals in voltage signals; The analog-to-digital converter is used to output the signal output by the low-pass filter after analog-to-digital conversion.

3. The range-expandable temperature measurement device based on multiplexing of multiple reference resistors according to claim 1, characterized in that: The AC carrier source comprises: A reference source, used to generate an output DC signal; A proportional amplifier, using an operational amplifier and a fixed resistor, is used to provide the required gain for the DC signal and generate an amplitude signal required by the AC carrier; Crystal oscillator, used to generate the frequency signal required for the AC carrier; The analog switch is used to output an AC carrier according to the amplitude signal and the frequency signal.

4. The range-expandable temperature measurement device based on multiplexing of multiple reference resistors according to claim 1, characterized in that: In a parallel Wheatstone bridge, the resistance of the reference resistor is related to the parameter characteristics of the thermistor itself; After determining the temperature measurement range, the entire temperature measurement range is divided into several temperature measurement sections, and the middle temperature point of the temperature measurement section is selected as the temperature measurement balance working point. Then, the resistance value of each reference resistor is determined in combination with the resistance value of the thermistor at each temperature measurement balance working point temperature.

5. The range-expandable temperature measurement device based on multiplexing of multiple reference resistors according to claim 1, characterized in that: The method for determining the functional relationship between temperature and voltage is: Before temperature measurement, the temperature measuring devices when each reference resistor is switched are calibrated respectively, a constant temperature box is selected to apply a temperature step signal, and the voltage signal output by the processing module is measured; then a thermometer is used for synchronous acquisition, and finally, the functional relationship between the temperature and voltage corresponding to the switching of each reference resistor is obtained through data fitting.

6. The range-expandable temperature measurement device based on multiplexing of multiple reference resistors according to claim 1, characterized in that: The temperature measuring device is suitable for use in satellite-borne technology and is used to measure the temperature of a core load sensitive structure in space gravitational wave detection.

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