A high-precision temperature measuring system and device suitable for deep hypothermia

Abstract

The application discloses a high-precision temperature measuring system and device suitable for deep low temperature, which comprises an excitation module, a collection and calibration module and a signal processing module; the excitation module is connected between the signal processing module and the collection and calibration module, generates an excitation signal according to a control signal of the signal processing module and transmits the excitation signal to the collection and calibration module; the collection and calibration module comprises a temperature collection unit and a calibration unit, the temperature collection unit is used for connecting an external temperature sensor and outputting a corresponding original electric signal; the calibration unit is connected to an excitation loop and outputs a standard calibration signal; the signal processing module receives the original electric signal or the standard calibration signal output by the collection and calibration module, outputs an excitation control signal to the excitation module after processing, so as to adjust parameters of the excitation signal; meanwhile, the signal processing module outputs a mode control signal to the collection and calibration module, so as to switch a working mode of the temperature collection unit or a working mode of the calibration unit. The application can realize the precision measurement requirement of deep low temperature ±0.001K.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature measurement, in particular to a high-precision temperature measurement system and device suitable for deep cryogenic temperature. BACKGROUND

[0002] In scientific and industrial scenarios such as hydrogen liquefaction, helium liquefaction, superconducting equipment, nuclear fusion, aerospace, quantum computing, etc., high-precision temperature measurement in deep cryogenic environments is a core requirement to ensure the safe and stable operation of the system. The operation of key equipment such as planar detectors requires precise monitoring of specific deep cryogenic temperature intervals with an accuracy of ±10mK or below, which poses extremely high requirements on the precision, anti-interference ability, and self-calibration performance of the temperature measurement system.

[0003] The current technology has obvious limitations and cannot meet the above-mentioned scene requirements: on the one hand, the precision and anti-interference ability of the deep cryogenic temperature measurement system are insufficient, such as the scheme mentioned in CN111780881B, which relies on fixed constant current excitation and cannot adapt to the dynamic needs of different types of deep cryogenic sensors. In addition, long-term operation is prone to precision drift due to circuit temperature drift and device aging, and requires external equipment for regular calibration, which is cumbersome and affects continuous operation of the system; on the other hand, the low-temperature sensor calibration is inefficient and costly, such as the calibration scheme mentioned in CN118258517A, which requires separate calibration and cannot adapt to the rapid deployment needs of batch sensors, further restricting the application efficiency of the deep cryogenic temperature measurement system.

[0004] In view of the above related technologies, the existing scheme cannot meet the comprehensive temperature measurement needs of high precision, high stability, and high efficiency in deep cryogenic scenes, and there is an urgent need for a high-precision temperature measurement scheme. SUMMARY

[0005] To solve the above technical problems, the present application provides a high-precision temperature measurement system and device suitable for deep cryogenic temperature.

[0006] In a first aspect, the present application provides a high-precision temperature measurement system suitable for deep cryogenic temperature, which adopts the following technical scheme:

[0007] The application discloses a high-precision temperature measuring system suitable for deep low temperature, which comprises an excitation module, a collection and calibration module and a signal processing module; the excitation module is connected between the signal processing module and the collection and calibration module, and is used for generating an excitation signal according to a control signal of the signal processing module and transmitting the excitation signal to an excitation input end of the collection and calibration module; the collection and calibration module comprises a temperature collection unit and a calibration unit; the temperature collection unit is used for connecting an external temperature sensor, connecting the excitation module through the excitation input end, receiving the excitation signal and outputting an original electric signal corresponding to an external temperature; the calibration unit is connected with the signal processing module through a control end, connects an excitation loop under the control of the signal processing module and outputs a standard calibration signal; the signal processing module is connected with the collection and calibration module and the excitation module respectively, receives the original electric signal or the standard calibration signal output by the collection and calibration module, outputs an excitation control signal to the excitation module after processing, so as to adjust parameters of the excitation signal; and the signal processing module outputs a mode control signal to the collection and calibration module, so as to switch a working mode of the temperature collection unit or a working mode of the calibration unit.

[0008] By adopting the technical scheme, the system adopts a "dynamic excitation + real-time calibration" structure to build a deep low temperature high-precision temperature measuring scheme, so as to solve the problems that the existing temperature measuring system cannot cover a low temperature of 100 mK-77K, the precision is only ±0.6K, the system does not have a self-calibration function and is greatly affected by an environmental temperature. On one hand, the excitation module can adjust parameters according to the control of the signal processing module, provides adaptive excitation signals (such as 100 nA-1 mA variable constant current) for different types of deep low temperature sensors (such as diode type and resistance type), and ensures that the sensors work in an optimal precision state. On the other hand, the calibration unit (such as a high-precision reference resistor) of the collection and calibration module is connected to an excitation loop, and outputs a standard calibration signal. The signal processing module can calculate system errors and compensate based on the standard calibration signal, so as to prevent long-term drift from affecting the precision. The mode switching function realizes "temperature measurement-calibration" integration, does not need to perform a cooling calibration process for each sensor separately, can complete dynamic calibration in a normal operation of the device, does not need external equipment assistance, greatly reduces calibration cost and improves efficiency, adapts to the rapid calibration demand of batch sensors, adapts to the demand of 100 mK-350K full range ±0.001K precision in hydrogen liquefaction and superconducting equipment scenes, and solves the pain points of insufficient deep low temperature measuring precision and no self-calibration capability of traditional systems.

[0009] Optionally, the signal processing module comprises an analog-to-digital conversion unit, a digital signal processing unit and a master control unit; the input end of the analog-to-digital conversion unit is connected with the signal output end of the acquisition calibration module, for converting the input original electric signal or standard calibration signal into a digital signal; the digital signal processing unit is connected with the output end of the analog-to-digital conversion unit, for correcting the digital signal in a non-linear manner, and at the same time, combining the environmental temperature compensation parameter output by the compensation module to dynamically correct the temperature data; the master control unit is electrically connected with the digital signal processing unit, the excitation module and the acquisition calibration module, for calculating the system error based on the deviation of the standard calibration signal and the theoretical value, and controlling the digital signal processing unit to compensate by using the system error, at the same time, outputting a gear control signal to the excitation module to adjust the excitation parameter, and outputting a switching control signal to the acquisition calibration module to switch the working mode.

[0010] By adopting the above technical solution, the signal processing module realizes high-precision conversion + intelligent correction + centralized control: the 24-bit sigma-delta analog-to-digital conversion unit ensures high-resolution conversion of the original electric signal and the standard calibration signal; the digital signal processing unit eliminates the non-linear error of the sensor under deep low temperature through non-linear correction (such as piecewise polynomial fitting), and further corrects the data in combination with the environmental compensation parameter; the master control unit plans the system error calculation, excitation adjustment and mode switching, realizes "calibration-temperature measurement" closed-loop control, ensures the measurement accuracy and stability within the full range, and adapts to the dynamic process control demand under the deep low temperature scene.

[0011] Optionally, the calibration unit comprises a reference resistor array, an analog switch array and a switching control circuit; the reference resistor array comprises at least two reference resistors with different resistance values, for generating adaptive standard calibration signals under different excitation gears; the input end of the analog switch array is connected with the output end of the reference resistor array and the output end of the temperature acquisition unit respectively, and the output end is connected to the signal processing module, for selectively outputting the standard calibration signal of the reference resistor array or the original electric signal of the temperature acquisition unit to the signal processing module under the driving of the switching control circuit; the input end of the switching control circuit is connected with the signal processing module, and the output end is connected with the control end of the analog switch array, for receiving the mode control signal of the signal processing module to drive the analog switch array to switch the path.

[0012] By adopting the technical scheme, the calibration unit realizes "multi-gear adaptation + rapid switching": the reference resistor array (such as a standard resistor with a resistance precision of 0.01% and a temperature coefficient of ≤1ppm / ℃) adapts to different excitation gears to ensure the accuracy of the calibration signal under each gear; the analog switch array (with a conduction resistor <1Ω and an isolation degree >100dB) realizes low-loss switching of the calibration and temperature measurement paths; and the switching control circuit responds to the instructions of the signal processing module to complete millisecond-level path switching and support periodic automatic calibration (such as once per hour) to ensure long-term measurement accuracy and solve the problem of no self-calibration or complicated calibration of traditional systems.

[0013] Optionally, the temperature acquisition unit comprises a current signal interface pair and a voltage signal interface pair; the current signal interface pair is connected with the output end of the excitation module and is used for applying an excitation signal to the external temperature sensor; and the voltage signal interface pair is used for acquiring a voltage generated on the external temperature sensor based on the excitation signal and transmitting the voltage as a raw electrical signal to the acquisition and calibration module.

[0014] By adopting the technical scheme, the four-wire acquisition design eliminates the influence of lead resistance: the current signal interface pair separately transmits the excitation current to avoid the voltage drop interference of the current on the lead; and the voltage signal interface pair only acquires the voltage across the sensor and does not carry the excitation current, thereby eliminating the measurement error caused by the lead resistance in structure and ensuring the measurement accuracy in a deep low-temperature zone (such as 4.215K liquid helium temperature) to solve the error problem of traditional two-wire acquisition caused by lead resistance.

[0015] Optionally, the system further comprises a compensation module connected with the signal processing module and used for detecting the ambient temperature of the high-precision temperature measurement system and transmitting a compensation parameter corresponding to the ambient temperature to the signal processing module.

[0016] By adopting the technical scheme, the compensation module provides "ambient temperature dynamic correction" for the system: the ambient temperature around the system is detected in real time, the signal processing module corrects the measurement data in combination with the parameter to eliminate the influence of ambient temperature change on the ADC reference and the resistor characteristics, ensure that the measurement accuracy still maintains the level of ±0.001K in a temperature fluctuation scenario (such as a laboratory environment with temperature change), and solve the problem of large influence of the traditional system on the ambient temperature.

[0017] Optionally, the digital signal processing unit stores segmented interval data of a target temperature zone and polynomial coefficients corresponding to each segmented interval; the polynomial coefficients are generated through comparison and calculation of a standard calibration signal output by the calibration unit and a theoretical value; and the digital signal processing unit determines the segmented interval to which the input digital signal belongs and calls the corresponding polynomial coefficient to correct the digital signal.

[0018] By adopting the technical scheme, the segmented polynomial correction adapts to the nonlinear characteristics in the full temperature range: for the nonlinear differences of the sensor in 100mK-350K, the temperature range is segmented and the corresponding polynomial coefficients (calibrated by a standard calibration signal) are stored, without the need to perform a cooling calibration process for each sensor, and the dynamic calibration can be completed in the normal operation of the device, greatly reducing the calibration cost and improving the efficiency, adapting to the rapid calibration needs of batch sensors; the digital signal processing unit calls the coefficients according to the interval of the input signal, realizes accurate nonlinear correction, and ensures that the accuracy of each temperature range (such as 100mK-20K deep low temperature range, 20K-77K medium low temperature range, and 77K-350K normal temperature range) reaches ±0.001K, solving the problem that the traditional single linear correction cannot cover the full temperature range.

[0019] Optionally, the excitation module includes a reference voltage source, a voltage-controlled current source, and a digital control resistor array, the digital control resistor array includes a plurality of resistors; the reference voltage source is used to output a reference voltage, and an output end of the reference voltage source is connected to a reference voltage input end of the voltage-controlled current source; a control end of the digital control resistor array is connected with the signal processing module, used to receive a gear control signal output by the signal processing module, and select one resistor to access a current setting loop of the voltage-controlled current source, used to convert the reference voltage into a set current; the voltage-controlled current source generates an excitation current signal proportional to the set current based on the set current, and outputs to the excitation loop.

[0020] By adopting the technical scheme, the excitation module realizes "precise variable constant current output": the reference voltage source (low offset, low temperature drift) provides a stable reference; the digital control resistor array (high-precision low-temperature drift resistor) selects resistors through gear control to convert the reference voltage into a set current in the range of 100nA-1mA; the voltage-controlled current source (Howland structure) ensures that the output current is not affected by the change of load impedance, with an accuracy of 0.01%, adapting to the excitation needs of different deep low temperature sensors (such as small current in the ultra-low temperature area and large current in the high temperature area), solving the problem that the traditional fixed excitation cannot adapt to multiple types of sensors.

[0021] Optionally, the excitation current output by the excitation module is 100nA-1mA. This current range can adapt to the excitation needs of different types of deep low temperature sensors (such as resistor type and diode type) in the full temperature range of 100mK-350K, solving the contradiction between "deep low temperature anti-self heating" and "normal temperature signal strength" that cannot be considered in the traditional fixed current excitation.

[0022] Optionally, it further includes an interaction module connected with the signal processing module, including: a multi-machine interconnection unit for cascading networking with other temperature measurement systems through a bus interface; a display unit for displaying measurement parameters; and a peripheral communication unit for data interaction with an upper computer or an external control system.

[0023] By adopting the technical scheme, the interaction module improves the practicability and expansibility of the system: the multi-machine interconnection unit supports multi-module cascading (such as multi-node temperature measurement of a hydrogen liquefaction device and a nuclear fusion experimental device), accurately matches the centralized monitoring needs of a large system; the display unit presents key temperature data and system status in a deep low-temperature scene in real time, and can realize on-site quick viewing without external equipment; and the peripheral communication unit supports remote control and data uploading, and adapts to the remote management needs of a large system such as hydrogen liquefaction and nuclear fusion, thereby solving the problems of single interaction, poor expansibility, and inability to meet the needs of multi-node monitoring, on-site quick viewing, and remote integrated management in a deep low-temperature high-precision temperature measurement scene in a traditional system.

[0024] In a second aspect, the application provides a high-precision temperature measurement device, which adopts the following technical scheme: a high-precision temperature measurement device, comprising a shell and a high-precision temperature measurement system integrated in the shell, as described in any one of the first aspect.

[0025] By adopting the technical scheme, the high-precision temperature measurement device realizes "high integration + deep low-temperature adaptation": the modules of excitation, collection and calibration, and signal processing are integrated in the shell, which is compact in structure and reduces external interference; in combination with the full-temperature-zone (100 mK-350 K) measurement capability, ±0.001 K precision, and self-calibration function of the high-precision temperature measurement system, the high-precision temperature measurement device can be directly applied to scenes such as a hydrogen liquefaction device (20.28 K liquid hydrogen temperature control), a superconducting magnet (4.215 K liquid helium cooling), and quantum computing, without relying on external calibration equipment and electrical cabinets, and the shell can be designed to adapt to IP protection levels to meet different environmental installation needs. Compared with a traditional distributed temperature measurement system, the high-precision temperature measurement device greatly improves the ease of use and reliability, and adapts to the stringent needs of scientific research and industrial scenes for deep low-temperature high-precision temperature measurement.

[0026] In summary, the application includes at least one of the following beneficial technical effects:

[0027] 1. The system constructs a high-precision cryogenic temperature measurement scheme with "dynamic excitation + real-time calibration". On the one hand, the excitation module can adjust parameters according to the signal processing module to provide adaptive excitation signals (such as 100nA-1mA variable constant current) for different types of cryogenic sensors (such as diode type and resistor type), ensuring that the sensor works in the best precision state. On the other hand, the calibration unit (such as high-precision reference resistor) of the acquisition calibration module is connected to the excitation circuit, and outputs a standard calibration signal. The signal processing module can calculate the system error based on this and compensate to prevent long-term drift from affecting precision. The mode switching function realizes the integration of "temperature measurement-calibration", eliminating the need for separate cooling calibration procedures for each sensor. Dynamic calibration can be completed during normal operation of the device without the need for external equipment, significantly reducing calibration costs and improving efficiency. It is suitable for batch sensor rapid calibration requirements and meets the needs of 100mK-350K full range ±0.001K precision in hydrogen liquefaction and superconducting device scenarios, solving the problems of insufficient cryogenic measurement precision and lack of self-calibration capability in traditional systems.

[0028] 2. The calibration unit realizes "multi-gear adaptation + fast switching": the reference resistor array adapts to different excitation gears to ensure accurate calibration signals at each gear. The analog switch array realizes low-loss switching of the calibration and temperature measurement paths. The switching control circuit responds to the signal processing module instructions to complete millisecond-level path switching, supporting periodic automatic calibration (such as once an hour) to ensure long-term measurement accuracy and solve the problem of no self-calibration or complicated calibration in traditional systems.

[0029] 3. The excitation module realizes "precise variable constant current output": the reference voltage source provides a stable reference; the digital control resistor array selects resistors through gear control to convert the reference voltage into a set current in the range of 100nA-1mA; the voltage-controlled current source ensures that the output current is not affected by changes in load impedance, with an accuracy of 0.01%, which adapts to the excitation needs of different cryogenic sensors (such as small current in the ultra-low temperature zone and large current in the high temperature zone), solving the problem of traditional fixed excitation that cannot adapt to multiple types of sensors. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the circuit structure diagram of the high-precision temperature measurement system provided by the embodiment of the present application;

[0031] Figure 2 is the circuit structure diagram of the high-precision temperature measurement system provided by the embodiment of the present application;

[0032] Figure 3 is the circuit structure diagram of the high-precision temperature measurement system provided by the embodiment of the present application.

[0033] REFERENCE SIGNS:

[0034] 10. Acquisition and calibration module; 11. Temperature acquisition unit; 12. Calibration unit; 121. Reference resistor array; 122. Analog switch array; 123. Switching control circuit; 13. Temperature sensor; 20. Excitation module; 21. Reference voltage source; 22. Voltage-controlled current source; 23. Digitally controlled resistor array; 30. Signal processing module; 31. Analog-to-digital converter unit; 32. Digital signal processing unit; 33. Main control unit; 34. Programmable gain amplifier; 40. Compensation module; 50. Multi-machine interconnection unit; 60. Display unit; 70. Peripheral communication unit. Detailed Implementation

[0035] The following is in conjunction with the appendix Figures 1-3 This application will be described in further detail.

[0036] This application discloses a high-precision temperature measurement system suitable for deep cryogenic environments. (Refer to...) Figure 1 The high-precision temperature measurement system includes an excitation module 20, an acquisition and calibration module 10, and a signal processing module 30. The excitation module 20 is connected between the signal processing module 30 and the acquisition and calibration module 10, and is used to generate an excitation signal according to the control signal of the signal processing module 30, and transmit it to the excitation input terminal of the acquisition and calibration module 10. The acquisition and calibration module 10 includes a temperature acquisition unit 11 and a calibration unit 12. The temperature acquisition unit 11 is used to connect to an external temperature sensor 13, and is connected to the excitation module 20 through the excitation input terminal. It receives the excitation signal and outputs the original electrical signal corresponding to the external temperature. The calibration unit 12 is connected to the signal processing module 30 through the control terminal. Under the control of the signal processing module 30, it connects to the excitation loop and outputs a standard calibration signal. The signal processing module 30 is connected to the acquisition and calibration module 10 and the excitation module 20 respectively. It receives the original electrical signal or the standard calibration signal output by the acquisition and calibration module 10, processes it, and outputs an excitation control signal to the excitation module 20 to adjust the parameters of the excitation signal. At the same time, it outputs a mode control signal to the acquisition and calibration module 10 to switch the working mode of the temperature acquisition unit 11 or the working mode of the calibration unit 12.

[0037] Specifically, such as Figure 1 As shown, in one embodiment, the excitation module 20 is a variable constant current source, serving as the core of the system's signal excitation. It mainly provides stable and precise current excitation for the external cryogenic temperature sensor 13 (such as a resistor-type or diode-type sensor). This module supports multiple current adjustment levels within the range of 100nA-1mA, with a current output accuracy better than 0.01%. It can adapt to the measurement requirements of the entire temperature range of 100mK-350K, ensuring that different types of sensors can output stable and recognizable electrical signals in each temperature range, laying the foundation for subsequent high-precision acquisition.

[0038] The temperature acquisition unit 11 comprises a current signal interface pair and a voltage signal interface pair, the current signal interface pair is connected with the output end of the excitation module 20, and is used for applying an excitation signal to the external temperature sensor 13; the voltage signal interface pair is used for acquiring the voltage generated on the external temperature sensor 13 based on the excitation signal and transmitting the voltage as a raw electrical signal to the acquisition calibration module 10, as shown in the figure. Figure 1 In an embodiment, a four-wire sensor interface is adopted, which has the dual functions of signal acquisition and system self-calibration, wherein the four-wire sensor interface comprises V+ / V- voltage measurement ends (voltage signal interface pair) and I+ / I- current excitation ends (current signal interface pair), the four-wire acquisition design can eliminate the influence of lead resistance, the current signal interface pair separately transmits excitation current, avoiding the voltage drop interference of current on the lead; the voltage signal interface pair only acquires the voltage between the sensor or the calibration circuit, and does not bear the excitation current, which eliminates the measurement error caused by lead resistance in structure, ensures the measurement accuracy in the deep low temperature area (such as 4.215K liquid helium temperature), solves the error problem caused by lead resistance in the traditional two-wire acquisition, effectively eliminates the interference of lead resistance on the weak μV-level voltage signal, and accurately acquires the raw electrical signal corresponding to the external temperature;

[0039] The calibration circuit (built-in reference resistor group, analog switch array 122) constitutes a calibration unit 12, which can be connected to the excitation loop under the control of the signal processing module 30, and outputs a standard calibration signal corresponding to a known resistance value, which is used for correcting the drift error in the long-term operation of the system, and ensuring the stability of the measurement accuracy;

[0040] Referring to Figure 1 In an embodiment, the signal processing module 30 comprises an analog-to-digital conversion unit 31, a digital signal processing unit 32 and a main control unit 33; the input end of the analog-to-digital conversion unit 31 is connected with the signal output end of the acquisition calibration module 10, which is used for converting the input raw electrical signal or standard calibration signal into a digital signal; the digital signal processing unit 32 is connected with the output end of the analog-to-digital conversion unit 31, which is used for correcting the nonlinearity of the digital signal; the main control unit 33 is electrically connected with the digital signal processing unit 32, the excitation module 20 and the acquisition calibration module 10, which is used for: calculating the system error based on the deviation of the standard calibration signal from the theoretical value, and controlling the digital signal processing unit 32 to compensate by using the system error, at the same time, outputting a gear control signal to the excitation module 20 to adjust the excitation parameters, and outputting a switching control signal to the acquisition calibration module 10 to switch the working mode.

[0041] Specifically, as Figure 1As shown, in a preferred embodiment, the signal processing module 30 includes a PGA (programmable gain amplifier 34), an ADC (analog-to-digital conversion circuit), an FPGA (digital signal processing unit 32), and an MCU (main control unit 33), which is the data processing and control center of the system, realizing high-precision conversion + intelligent correction + centralized control. The core logic is as follows: first, the original electrical signal or standard calibration signal output by the acquisition calibration module 10 is gain-adjusted by the PGA, and then the analog-to-digital conversion of the signal is completed by the 24-bit sigma-delta ADC, ensuring high-resolution conversion of the original electrical signal and the standard calibration signal; then the FPGA realizes high-speed digital filtering, real-time data alignment, and preliminary nonlinear correction (such as piecewise polynomial fitting) to eliminate the nonlinear error of the sensor at low temperature; finally, the MCU performs temperature conversion and system error compensation (based on the standard calibration signal), and outputs gear control signals to the excitation module 20 and mode switching signals to the acquisition calibration module 10. The main control unit 33 coordinates system error calculation, excitation adjustment, and mode switching, realizes "calibration-temperature measurement" closed-loop control, ensures measurement accuracy and stability within the full range, adapts to dynamic process control requirements in deep low temperature scenes, and realizes ultra-high measurement accuracy of ±0.001K in the temperature range of 100mK-350K.

[0042] By adopting the above technical scheme, in view of the problems that the existing temperature measurement system cannot cover the low temperature range of 100mK-77K, the precision is only ±0.6K, there is no self-calibration, and it is greatly affected by the environment temperature, the system constructs a deep low temperature high precision temperature measurement scheme based on "dynamic excitation + real-time calibration": on the one hand, the excitation module 20 can adjust parameters controlled by the signal processing module 30 to provide adaptive excitation signals (such as 100nA-1mA variable constant current) for different types of deep low temperature sensors (such as diode type and resistor type), ensuring that the sensor works in the best precision state; on the other hand, the calibration unit 12 (such as a high-precision reference resistor) of the acquisition calibration module 10 is connected to the excitation circuit to output a standard calibration signal, and the signal processing module 30 can calculate and compensate the system error based on the standard calibration signal, preventing long-term drift from affecting the precision; the mode switching function realizes "temperature measurement-calibration" integration, eliminating the need for separate cooling calibration procedures for each sensor, and enabling dynamic calibration during normal operation of the device without the need for external equipment, greatly reducing calibration costs and improving efficiency, adapting to the rapid calibration needs of batch sensors, and meeting the needs of 100mK-350K full range ±0.001K precision in hydrogen liquefaction and superconducting device scenes, solving the pain points of insufficient deep low temperature measurement precision and lack of self-calibration capability of traditional systems.

[0043] To further improve the intelligent level and long-term stability of the system, in an embodiment, the signal processing module 30 also integrates an intelligent calibration and adaptive filtering mechanism based on statistical process control (SPC). The mechanism upgrades the calibration behavior of the system from passive execution at a fixed period to on-demand active triggering based on data quality.

[0044] Specifically, the digital signal processing unit 32 (FPGA) is built-in with an SPC algorithm module, which monitors the digital signal stream output by the analog-to-digital conversion unit 31 (ADC) in real time and analyzes the statistical characteristics thereof. For example, in a stable temperature measurement environment, the FPGA calculates and maintains a baseline of the short-term mean and standard deviation of the measured signal value. When the system is subjected to external strong electromagnetic interference, the sensor exhibits transient abnormalities, or the circuit itself begins to exhibit early drift, the statistical characteristics of the measured signal will change, such as a sudden increase in the standard deviation or a significant deviation of the mean. Once the FPGA detects that these statistical indicators exceed the preset control limits, it determines that the system may be in a non-steady state and immediately sends an interrupt request to the host unit 33 (MCU) to actively trigger a complete self-calibration process. This "on-demand calibration" mechanism can respond to system state changes more timely than fixed timing calibration, and corrects errors at an early stage to prevent error accumulation.

[0045] Meanwhile, the mechanism also includes an adaptive filtering function. The FPGA dynamically adjusts the parameters of its internal digital filter (such as FIR or IIR filter) according to the real-time calculated signal-to-noise ratio (SNR) or standard deviation. For example, in a clean signal and low noise environment, the FPGA automatically selects a narrower filter passband and fewer orders to obtain faster system response speed; conversely, in a noisy environment, it automatically switches to a filter mode with a narrower passband and higher orders to maximize noise suppression and ensure measurement accuracy. This adaptive filtering capability enables the system to dynamically achieve an optimal balance between response speed and measurement accuracy.

[0046] Through the cooperative work of the integrated intelligent calibration mechanism based on statistical process control (SPC) and the adaptive filtering mechanism, the system can trigger calibration on demand according to data quality, which is more timely and efficient than fixed period calibration; by tracking and analyzing the trend of the internal reference resistor over a long period of time, the health status of the calibration reference itself can be monitored and warned, ensuring not only ultra-high measurement accuracy, but also stronger environmental adaptability and self-diagnosis and repair capabilities, greatly improving the reliability of long-term unattended operation in complex industrial sites.

[0047] Reference Figure 1In an embodiment, the high-precision temperature measurement system provided by the embodiment of the present application further comprises a compensation module 40 connected to the signal processing module 30, for detecting the ambient temperature of the high-precision temperature measurement system, and transmitting the compensation parameter corresponding to the ambient temperature to the signal processing module 30, and the signal processing module 30 simultaneously combines the ambient temperature compensation parameter output by the compensation module 40 to dynamically correct the temperature data;

[0048] Specifically, in an embodiment, as shown in Figure 1 the high-precision temperature measurement system provided by the embodiment of the present application, the signal processing module 30 simultaneously combines the ambient temperature compensation parameter output by the compensation module 40 to dynamically correct the temperature data, and the compensation module 40 comprises an ambient temperature compensation function unit, which is composed of a high-precision ambient temperature sensor 13 (such as a platinum resistor temperature sensor 13, with a measurement accuracy of ±0.01℃ and a resolution of 0.001℃) and a built-in micro-ADC (with a precision of 12 bits or more and a sampling rate of ≥1kHz, suitable for low-temperature drift scenarios). Among them, the ambient temperature sensor 13 is deployed near the core components of the system (such as the main ADC (Σ-Δ type ADC), reference resistor, operational amplifier), and real-time collection of the ambient temperature analog signals inside and around the module; the built-in micro-ADC is responsible for analog-to-digital conversion of the analog signals, preventing interference introduced by long-distance signal transmission, and the converted ambient temperature digital signals are transmitted to the FPGA (digital signal processing unit 32) of the signal processing module 30 through a data interface (such as I2C). The compensation algorithm module (as one of its functions) built in the FPGA, based on the received ambient temperature digital signals, calculates and generates quantized compensation parameters (such as electronic device temperature drift coefficient, main ADC reference voltage temperature correction value, resistor characteristic temperature offset, etc.), and synchronously to the MCU, the update frequency of the compensation parameter is synchronized with the temperature measurement period of the signal processing module 30 (such as updating once every 100ms), ensuring the timeliness of the compensation and adapting to the correction requirements of the ambient temperature fluctuation scenarios in the full temperature range of 100mK-350K.

[0049] By adopting the above technical solution, the compensation module 40 provides the system with "ambient temperature dynamic correction": real-time detection of the temperature around the system, the signal processing module 30 combines the ambient compensation parameter to further correct the data; the main control unit 33 coordinates the system error calculation, excitation adjustment and mode switching, realizes the "calibration-temperature measurement" closed-loop control, combines the parameter correction measurement data, eliminates the influence of ambient temperature change on the ADC reference and resistor characteristics, and ensures that the measurement accuracy still maintains the level of ±0.001K in the temperature fluctuation scenario (such as laboratory ambient temperature change), solving the problem of large influence of traditional systems on ambient temperature.

[0050] For reference Figure 2In one embodiment, the calibration unit 12 includes a reference resistor array 121, an analog switch array 122, and a switching control circuit 123. The reference resistor array 121 includes at least two reference resistors with different resistance values, used to generate a suitable standard calibration signal under different excitation levels. The input terminal of the analog switch array 122 is connected to the output terminal of the reference resistor array 121 and the output terminal of the temperature acquisition unit 11, respectively. The output terminal is connected to the signal processing module 30, used to selectively output the standard calibration signal of the reference resistor array 121 or the original electrical signal of the temperature acquisition unit 11 to the signal processing module 30 under the drive of the switching control circuit 123. The input terminal of the switching control circuit 123 is connected to the signal processing module 30, and the output terminal is connected to the control terminal of the analog switch array 122, used to receive the mode control signal of the signal processing module 30 and drive the analog switch array 122 to switch paths.

[0051] Specifically, such as Figure 2 As shown, in one embodiment, the acquisition and calibration module 10 is also provided with an interface for connecting an external temperature sensor 13 (e.g., Figure 2 SC-1 to SC-4 together constitute the temperature acquisition unit 11 and the interface for connecting the internal reference resistor (e.g., Figure 2 (SO-1 to SO-4 in the original text). In one embodiment, the system is designed to support the access of four external temperature sensors 13, and correspondingly incorporates four standard resistors as calibration references, achieving one-to-one channel verification. The reference resistor array 121 is composed of these standard resistors R (for ease of illustration, ...). Figure 2 (This is for illustrative purposes only and does not represent the actual number of standard resistors and temperature sensors 13. For example, metal foil or wire-wound standard resistors with resistance accuracy better than 0.01% and temperature coefficient less than 1ppm / ℃ are selected as the absolute calibration reference inside the system.)

[0052] Analog switch array 122 (e.g.) Figure 2 The central multiplexer matrix (S-1 to S-4) is used for signal selection. Its multiplexer inputs are connected to the voltage acquisition terminals of four external sensor interfaces (V+ and V- terminals of SC-1 to SC-4) and the voltage acquisition terminals of four standard resistors (V+ and V- terminals of SO-1 to SO-4), respectively. Its common output terminal is connected to the input terminal of the signal processing module 30 (specifically, the analog-to-digital converter unit 31).

[0053] The switching control circuit 123 is used to determine whether the system works in the "temperature measurement mode" or the "calibration mode". The switching control circuit 123 includes a relay K, a driving transistor Q1, etc. The signal processing module 30 (specifically, the MCU) controls the conduction or cut-off of the transistor Q1 by sending a mode control signal (an EN enable signal) to the base of the transistor Q1, thereby driving the contact switching of the relay K.

[0054] In addition, in order to ensure the long-term reliability of the self-calibration function of the system, in an embodiment, the main control unit 33 (such as an MCU, an MPU, a DSP, a SoC, a special ASIC, etc.) or the digital signal processing unit 32 (such as an FPGA, a CPLD, a DSP, an AI acceleration chip, etc.) can also perform long-term tracking and statistical analysis on the measurement value of the internal reference resistor. Specifically, the main control unit 33 (MCU) will record the measurement value of the internal standard resistor collected each time the calibration mode is executed in the non-volatile memory, forming a long-term historical database. By statistically analyzing these historical data (for example, calculating the drift rate or standard deviation thereof), it can be determined whether the reference resistor itself has drifted due to aging or environmental stress. When the cumulative drift amount converted into an equivalent temperature error exceeds a preset threshold (for example, ±0.0001K), the system will generate an alarm signal. The alarm signal can drive the display unit 60 to prompt, or send a status code to the upper computer through the peripheral communication unit 70, indicating that the device needs to be maintained or returned to the factory for re-calibration. Further, by extrapolating the drift trend, the system can also predict the remaining effective life of the reference resistor, realizing predictive maintenance warning. This "self-monitoring" mechanism for the calibration reference ensures the long-term effectiveness of the self-calibration function of the system, and solves the deep technical problem of overall inaccuracy of measurement results caused by aging of the calibration standard itself in high-precision instruments.

[0055] To further eliminate the influence of the non-linear characteristics of the deep cryogenic temperature zone sensor on the measurement accuracy, the digital signal processing unit 32 (FPGA) in the signal processing module 30 also needs to cooperate with the calibration unit 12 to complete the non-linear correction work. In an embodiment, the digital signal processing unit 32 stores the segmented interval data of the target temperature zone and the polynomial coefficients corresponding to each segmented interval; the polynomial coefficients are generated by comparing the standard calibration signal output by the calibration unit 12 with the theoretical value; the digital signal processing unit 32 determines the segmented interval to which the input digital signal belongs, and calls the corresponding polynomial coefficients to correct the digital signal. For example, the 100mK-350K full temperature zone is divided into three core segments: 100mK-4.2K (superfluid helium / liquid helium temperature zone), 4.2K-77K (deep cryogenic temperature zone), and 77K-350K (normal temperature to medium temperature zone). For each segment, a plurality of standard calibration signals (such as 100mK corresponding to SO-4 standard resistor signal, 4.2K corresponding to SO-3 standard resistor signal, 77K corresponding to SO-2 standard resistor signal, and 350K corresponding to SO-1 standard resistor signal) output by the calibration unit 12 are compared with the theoretical temperature-resistor relationship to calculate the third-order polynomial coefficients (such as 100mK-4.2K segment coefficients a0=-0.002, a1=1.05, a2=-0.03, a3=0.001) of each segment. When the FPGA receives a certain original electric signal (such as a signal corresponding to 2.17K superfluid helium temperature), it first determines that it belongs to the 100mK-4.2K segment, and then calls the polynomial coefficients of this segment to substitute into the formula T=a0+a1R+a2R²+a3R³ (T is the corrected temperature, and R is the resistor value corresponding to the original signal) to complete the accurate correction.

[0056] By adopting the above technical solution, the segmented polynomial correction adapts to the non-linear characteristics of the full temperature zone: for the non-linear differences of the sensor within 100mK-350K, the temperature zone is segmented and the corresponding polynomial coefficients (calibrated by standard calibration signals) are stored; the digital signal processing unit 32 calls the coefficients according to the interval to which the input signal belongs, realizes accurate non-linear correction, and ensures that each temperature zone (such as 100mK-20K deep cryogenic temperature zone, 20K-77K medium-low temperature zone, and 77K-350K normal temperature zone) reaches ±0.001K accuracy, solving the problem that the traditional single linear correction cannot cover the full temperature zone.

[0057] In an embodiment, the working mode switching and cooperation action flow of the system is also disclosed, which is as follows:

[0058] Temperature measurement mode: In the default state, or under the control of the signal processing module 30, the switching control circuit 123 does not act, and the normally closed contact of the relay K is connected. At this time, the excitation current generated by the excitation module 20 flows through the external temperature sensor 13 interface (one of SC-1 to SC-4), forming a temperature measurement loop. At the same time, the signal processing module 30 controls the analog switch array 122 to select the corresponding sensor voltage collection terminal. In this way, the voltage signal between the external temperature sensor 13 is collected as the original electric signal, and the system performs normal temperature measurement;

[0059] Calibration mode: When the system executes the automatic calibration process (such as power-on or timing trigger), the signal processing module 30 issues an instruction. First, the switching control circuit 123 acts to drive the normally open contact of the relay K to close. At this time, the excitation current is redirected and no longer flows to the external sensor, but flows through the internal standard resistor corresponding to the sensor channel (for example, when calibration channel 1, the current flows through SO-1). Then, the signal processing module 30 controls the analog switch array 122 to select the voltage collection terminal of the standard resistor (V+ and V- terminals of SO-1). The voltage across the standard resistor is collected as a standard calibration signal. The signal processing module 30 compares the collected value with the calibration value stored in the memory in advance, and calculates the gain and zero point error of the current system link (including the excitation source, amplifier, ADC, etc.) in real time, and generates a dynamic compensation coefficient. After calibration, the switching control circuit 123 returns to the temperature measurement mode;

[0060] When the system switches back to the temperature measurement mode, for each original electric signal collected from the external temperature sensor 13, the signal processing module 30 will call the latest compensation coefficient to perform real-time correction operation before converting it to the final temperature value. The correction operation can specifically include gain compensation and zero point bias adjustment of the original data, so as to offset the drift error introduced by the change of environmental temperature or the aging of components in the measurement link in the digital domain. In this way, the system ensures that each temperature reading output is a high-precision result after real-time calibration, rather than an uncorrected original measurement value, thereby realizing long-term measurement stability and reliability. Through the cooperative action of the above-mentioned "excitation current switching" and "signal selection switching", the system realizes seamless and time-sharing multiplexing measurement of the external sensor and the internal reference in the same set of measurement circuit.

[0061] It can be understood that the calibration unit 12 realizes the "multi-gear adaptation, high isolation, fast automatic" precision calibration. The reference resistor array 121 (for example, the ultra-high precision resistor of VISHAY is selected, and the resistance precision is 0.01%, and the temperature coefficient is ≤1ppm / ℃) can adapt to the measurement range under different excitation gears, and ensure that the standard calibration signal itself has very high accuracy and stability in the wide dynamic range from micro-ohm to kilo-ohm, and provides the basis for the final measurement precision of the system ±0.001K level; the analog switch array 122 (for example, the CMOS switch with on-resistance <1Ω and channel isolation >100dB) cooperates with the high isolation relay to realize the low-loss and low-crosstalk switching of the calibration path and the temperature measurement path. This double isolation mechanism effectively avoids the mutual interference between different signal paths, ensures that the weak temperature voltage signal (which can be as low as nanovolt level) is not distorted in the switching process, and solves the problem of additional error introduced by the switching switch in the traditional design; the switching control circuit 123 can accurately respond to the instructions of the signal processing module 30, and complete the path switching in the millisecond level, which enables the system to perform periodic (such as once an hour or triggered according to the environmental temperature change) full-automatic calibration, real-time tracking and compensation of the system drift caused by environmental temperature change and component aging, thereby ensuring the long-term measurement precision of the device for several years, and solving the problem that the traditional high-precision system relies on manual regular inspection and calibration, which is complicated and cannot guarantee the online precision.

[0062] With reference to Figure 3 In an embodiment, the excitation module 20 includes a reference voltage source 21, a voltage-controlled current source 22, and a digital control resistor array 23. The reference voltage source 21 is configured to output a reference voltage. The output terminal of the reference voltage source 21 is connected to the reference voltage input terminal of the voltage-controlled current source 22. The control terminal of the digital control resistor array 23 is connected to the signal processing module 30, configured to receive the gear control signal output by the signal processing module 30, and select the resistor with a specific resistance value. The digital control resistor array 23 includes a resistor network composed of a plurality of resistors. The resistor network is coupled to the current setting loop of the voltage-controlled current source 22, configured to convert the reference voltage into a set current. The voltage-controlled current source 22 generates an excitation current signal proportional to the set current based on the set current, and outputs the excitation current signal to the excitation loop.

[0063] Specifically, as Figure 3As shown, in an embodiment, the reference voltage source 21 is composed of a high-precision operational amplifier OP1 and a precision resistor network C-R1 to C-R4 configured to provide an input reference for it. The input signal Ui (VCC) is applied to the non-inverting input terminal (+) of OP1 through resistor C-R2, and OP1 simultaneously exists negative feedback (feedback of output UO1 to the inverting input terminal (-) through C-R3) and positive feedback (feedback to the non-inverting input terminal (+) through C-R2, C-R4 and a signal from OP2), which functions to adjust the output voltage UO1, thereby controlling the current IO flowing through the output resistor (a digitally controlled resistor array 23), preferably 100 nA-1 mA, which can be adapted to the excitation requirements of different types of deep cryogenic sensors (such as resistance type and diode type) in the full temperature range of 100 mK-350K. For example, for high-resistance sensors (such as some low-temperature platinum resistors) in the superfluid helium temperature range of 100 mK-4.2K, a small current of 100 nA-1 mA can prevent the self-heating effect of the sensor (excessive current can easily cause local temperature rise, which destroys the temperature authenticity in the deep cryogenic environment); for low-resistance sensors (such as conventional platinum resistors) in the normal temperature range of 77K-350K, a current of 10 mA-1 mA can generate a voltage signal with sufficient amplitude, which can adapt to the detection range of the ADC and reduce signal noise interference; at the same time, the wide range of 100 nA-1 mA can match the resistance change of the sensor in different temperature ranges (such as the significant increase in resistance of the sensor in deep cryogenic environment), ensuring that stable and accurately collectable electrical signals can be output in the full temperature range, providing excitation adaptation basis for the system to realize the measurement precision of ±0.001K in the temperature range of 100 mK-350K, and solving the contradiction between "deep cryogenic anti-self-heating" and "normal temperature signal strength" that cannot be considered in the traditional fixed current excitation;

[0064] To ensure the long-term stability of the reference voltage, the operational amplifier OP1 is selected to have a microvolt-level offset voltage and an extremely low temperature drift coefficient (such as ≤1 ppm / °C), and the voltage-controlled current source 22 is a high-precision operational amplifier OP2, whose non-inverting input terminal (+) is directly connected to the load (i.e., the external temperature sensor 13), for accurately "sensing" or "sampling" the voltage on the load. Since the input impedance of the operational amplifier is extremely high, OP2 hardly draws current from the output circuit when sampling the voltage, ensuring the accuracy of IO, and the voltage of the output UO2 of OP2 is equal to the voltage of its non-inverting input terminal, i.e., the voltage at the top of the load, and the other end of the load is grounded. Then, this voltage UO2 is fed back to the positive feedback network of OP1 (connected to C-R4), and OP1 and OP2 and their peripheral resistors constitute a Howland circuit that realizes constant current output through voltage feedback closed-loop control.

[0065] The digital control resistor array 23 includes a multi-channel analog switch K1 and a set of precision resistors, such as C-R5 to C-R9. The signal processing module 30 (specifically, the MCU) sends gear control signals to the analog switch K1 through address lines (A0, A1, A2) and an enable signal (EN), and selectively connects a target resistor in C-R5 to C-R9 to OP1 and OP2 circuits. These resistors are high-precision, low-temperature-drift models. By switching different resistors, the gain of the circuit can be accurately changed to set different target current gears.

[0066] The generation process of the precision excitation current is as follows:

[0067] The generation of the entire excitation current is a closed-loop control process precisely programmed by the signal processing module 30 (MCU) and real-time feedback.

[0068] First, in the system initialization phase, the MCU will first identify the type of external sensor connected according to the preset configuration or communication protocol after power-on. Based on the characteristic curve of the sensor (such as sensitivity at different temperature zones), the MCU will determine an optimal excitation current range to lay the foundation for subsequent accurate setting;

[0069] Second, enter the resistor gear selection and setting phase. The MCU sends address signals (A0, A1, A2) and an enable signal (EN) to the multi-channel analog switch K1 through its I / O port based on the calculated target current value. This control signal will accurately select one target resistor in C-R5 to C-R9 and connect it to the Howland circuit as the core setting resistor that determines the voltage-to-current conversion ratio. After the switch action is completed, the MCU will execute a short delay (for example, wait for 100 μs) to ensure that the transient process of the analog switch is over and the entire analog circuit reaches a complete steady state;

[0070] Then, the constant current source starts and stabilizes the output. Once the circuit is stable, the reference voltage source 21 composed of OP1 and the Howland voltage-controlled current source 22 composed of OP1, OP2, and surrounding resistors begin to work together. OP1 and OP2 adjust the output voltage UO1 of OP1 through precise negative feedback and positive feedback networks, ensuring that a constant voltage difference proportional to the reference voltage is formed across the selected setting resistor (one of C-R5 to C-R9). This voltage difference generates an extremely stable current IO on the setting resistor, which is the final precision excitation current output to the external sensor. Thanks to the excellent load regulation characteristics of the Howland circuit topology, even if the resistance of the external sensor fluctuates dramatically due to temperature changes, the output current IO can still remain highly constant.

[0071] To achieve the ultimate precision, the system also includes real-time precision guarantee and dynamic adjustment mechanism. On the one hand, the MCU will monitor the stability of the output current in real time through the subsequent sampling circuit. When the current fluctuation exceeds the preset high-precision threshold (such as 0.01%), the MCU will trigger the automatic calibration program to fine-tune the reference voltage or re-evaluate the resistor gear, forming a dynamic error correction closed loop. At the same time, the co-processed FPGA can also implement digital filtering algorithm in parallel, effectively filtering out current ripple, and suppressing the final output current noise to a very low level (such as within 0.1 μA RMS); on the other hand, during the entire measurement process, the MCU can dynamically adjust the excitation current according to the real-time response characteristics of the sensor. For example, in the extremely low temperature area where high signal-to-noise ratio is required, automatically switch to small current gear to reduce self-heating effect; while in the high temperature area where the sensor sensitivity decreases, it can switch to large current gear to enhance signal strength, so as to achieve optimal measurement performance in the entire working temperature range.

[0072] By adopting the above technical scheme, the excitation module 20 realizes "precise variable constant current output": the reference voltage source 21 (low offset, low temperature drift) provides stable reference; the digital control resistor array 23 (high-precision low-temperature-drift resistor) converts the reference voltage into a set current in the range of 100 nA-1 mA through gear control resistor selection; the voltage-controlled current source 22 (Howland structure) ensures that the output current is not affected by the change of load impedance, with a precision of 0.01%, which adapts to the excitation requirements of different deep low temperature sensors (such as small current in extremely low temperature area and large current in high temperature area), and solves the problem that traditional fixed excitation cannot adapt to multiple types of sensors.

[0073] Referring to Figure 1 In an embodiment, an interaction module is included, which is connected with the signal processing module 30 and includes: a multi-machine interconnection unit 50 for cascading networking with other temperature measurement systems through a bus interface; a display unit 60 for displaying measurement parameters; and a peripheral communication unit 70 for data interaction with an upper computer or an external control system.

[0074] Specifically, as Figure 1As shown, in an embodiment, the interaction module mainly includes three units on hardware, first is the multi-machine interconnection unit 50, the physical interface is bus interface (for example, RS-485 or CAN bus), this unit enables multiple temperature measurement systems to be conveniently cascaded through the bus to form a distributed temperature measurement network, and the MCU can realize the cooperative work, data synchronization or master-slave control between multiple devices by controlling the multi-machine interconnection unit 50; it also includes a display unit 60, such as an LCD display screen or an OLED screen, the MCU will render and present the key measurement parameters such as real-time temperature value, current excitation current level, system working state (such as measurement, standby, calibration) and other information on the screen in real time through the driving circuit, providing an intuitive man-machine interface for the on-site operator; and a peripheral communication unit 70, which integrates multiple standard communication interfaces, such as USB interface, which can realize direct connection with the host computer (such as computer), support batch export of measurement data, configuration and writing of system parameters (such as calibration coefficient, temperature measurement period), and at the same time compatible with Modbus and other industrial communication protocols, facilitating the connection with external control systems (such as PLC) to realize remote monitoring and integrated management of temperature measurement data.

[0075] By adopting the above technical scheme, the interaction module improves the practicability and expansibility of the system: the multi-machine interconnection unit 50 supports multi-module cascading (such as multi-node temperature measurement of hydrogen liquefaction device and nuclear fusion experimental device), accurately matches the centralized monitoring needs of large systems; the display unit 60 presents the key temperature data (such as liquid helium 4.215K and liquid hydrogen 20.28K) and system state in real time, and can realize on-site quick viewing without external equipment; the peripheral communication unit 70 supports remote control (such as remote writing of sensor calibration curve) and data upload (such as data transmission to central controller), adapts to the remote management needs of large systems such as hydrogen liquefaction and nuclear fusion, and solves the problems of single interaction, poor expansibility and inability to meet the needs of multi-node monitoring, on-site quick viewing and remote integrated management in the deep low temperature high precision temperature measurement scene of traditional systems.

[0076] The application further discloses a high-precision temperature measuring device, which comprises a shell and a high-precision temperature measuring system integrated in the shell and any one of the above embodiments, wherein the high-precision temperature measuring system is integrated on the same PCB, the PCB adopts a high-density layout design, the core circuits of the variable constant current source circuit of the excitation module 20, the calibration circuit of the acquisition calibration module 10 and the four-wire sensor interface, the PGA / ADC / FPGA / MCU of the signal processing module 30, the environmental temperature sensor 13 of the compensation module 40 and the communication interface of the interaction module are all integrated on the single PCB, and the key devices (such as reference resistors, operational amplifiers and ADCs) are optimized in selection according to low-temperature characteristics, so as to ensure stable work in the temperature range of 100 mK-350K; the shell is made of metal material (such as aluminum alloy), has the functions of electromagnetic shielding and heat dissipation, can reduce the influence of external electromagnetic interference on the weak signal of the order of μV, the surface of the shell is reserved with standardized mounting interfaces (such as guide rail mounting grooves and flange interfaces), and the protection level of IP65 or above can be customized according to the application scene, so as to adapt to the installation requirements of scientific research / industrial scenes such as hydrogen liquefaction devices and superconducting devices; in addition, a low-power power supply unit is integrated in the shell, supports wide voltage input (such as 12V-24V DC), can be directly connected to the field power supply system, and does not need an additional power adapter.

[0077] By adopting the above technical scheme, the high-precision temperature measuring device realizes "high integration + deep low-temperature adaptation": the excitation module, the acquisition calibration module and the signal processing module are integrated in the shell, the structure is compact and external interference is reduced; in combination with the full-temperature range (100 mK-350K) measurement capability, ±0.001K precision and self-calibration function of the high-precision temperature measuring system, the high-precision temperature measuring device can be directly applied to scenes such as hydrogen liquefaction devices (20.28K liquid hydrogen temperature control), superconducting magnets (4.215K liquid helium cooling) and quantum computing, does not need to rely on external calibration equipment and electrical cabinets, the shell can be designed to adapt to the IP protection level, meets different environmental installation requirements, compared with a traditional distributed temperature measuring system, the high-precision temperature measuring device greatly improves the usability and reliability, and meets the strict requirements of scientific research and industrial scenes on deep low-temperature high-precision temperature measurement.

[0078] The above are preferred embodiments of the application, which do not limit the protection scope of the application, therefore: any equivalent changes made on the basis of the structure, shape and principle of the application should be covered by the protection scope of the application.

Claims

1. A high-precision temperature measurement system suitable for deep cryogenic temperatures, characterized in that, include: Excitation module (20), acquisition and calibration module (10) and signal processing module (30); The excitation module (20) is connected between the signal processing module (30) and the acquisition and calibration module (10), and is used to generate an excitation signal according to the control signal of the signal processing module (30) and transmit it to the excitation input terminal of the acquisition and calibration module (10); The acquisition and calibration module (10) includes a temperature acquisition unit (11) and a calibration unit (12). The temperature acquisition unit (11) is used to connect to an external temperature sensor (13), and is connected to the excitation module (20) through an excitation input terminal. It receives the excitation signal and outputs the original electrical signal corresponding to the external temperature. The calibration unit (12) is connected to the signal processing module (30) through a control terminal. Under the control of the signal processing module (30), it connects to the excitation circuit and outputs a standard calibration signal. The signal processing module (30) is connected to the acquisition and calibration module (10) and the excitation module (20) respectively. It receives the raw electrical signal or standard calibration signal output by the acquisition and calibration module (10), processes it, and outputs an excitation control signal to the excitation module (20) to adjust the parameters of the excitation signal. At the same time, it outputs a mode control signal to the acquisition and calibration module (10) to switch the working mode of the temperature acquisition unit (11) or the working mode of the calibration unit (12). The signal processing module (30) includes an analog-to-digital converter (31), a digital signal processing unit (32), and a main control unit (33). The input terminal of the analog-to-digital converter (31) is connected to the signal input terminal of the acquisition and calibration module (10). The output terminal is connected to convert the input raw electrical signal or standard calibration signal into a digital signal; the digital signal processing unit (32) is connected to the output terminal of the analog-to-digital conversion unit (31) for nonlinear correction of the digital signal; the main control unit (33) is electrically connected to the digital signal processing unit (32), the excitation module (20) and the acquisition and calibration module (10) respectively, for: calculating the system error based on the deviation between the standard calibration signal and the theoretical value, and controlling the digital signal processing unit (32) to use the system error for compensation, while outputting a gear control signal to the excitation module (20) to adjust the excitation parameters, and outputting a switching control signal to the acquisition and calibration module (10) to switch the working mode; The excitation module (20) includes a reference voltage source (21), a voltage-controlled current source (22), and a digitally controlled resistor array (23), wherein the digitally controlled resistor array (23) includes multiple resistors; The reference voltage source (21) is used to output a reference voltage. The output terminal of the reference voltage source (21) is connected to the reference voltage input terminal of the voltage-controlled current source (22). The control terminal of the digital control resistor array (23) is connected to the signal processing module (30) to receive the gear control signal output by the signal processing module (30) and select one of the resistors to be connected to the current setting circuit of the voltage-controlled current source (22) to convert the reference voltage into a set current. The voltage-controlled current source (22) generates an excitation current signal proportional to the set current based on the set current and outputs it to the excitation circuit.

2. The high-precision temperature measurement system according to claim 1, characterized in that: The calibration unit (12) includes a reference resistor array (121), an analog switch array (122), and a switching control circuit (123). The reference resistor array (121) includes at least two reference resistors with different resistance values, used to generate a suitable standard calibration signal under different excitation levels; The input terminal of the analog switch array (122) is connected to the output terminal of the reference resistor array (121) and the output terminal of the temperature acquisition unit (11), respectively. The output terminal is connected to the signal processing module (30) for selectively outputting the standard calibration signal of the reference resistor array (121) or the original electrical signal of the temperature acquisition unit (11) to the signal processing module (30) under the drive of the switching control circuit (123). The input terminal of the switching control circuit (123) is connected to the signal processing module (30), and the output terminal is connected to the control terminal of the analog switch array (122). It is used to receive the mode control signal from the signal processing module (30) and drive the analog switch array (122) to switch paths.

3. The high-precision temperature measurement system according to claim 1, characterized in that: The temperature acquisition unit (11) includes a current signal interface pair and a voltage signal interface pair; The current signal interface is connected to the output of the excitation module (20) and is used to apply the excitation signal to the external temperature sensor (13); the voltage signal interface is used to acquire the voltage generated on the external temperature sensor (13) based on the excitation signal and transmit it as the raw electrical signal to the acquisition and calibration module (10).

4. The high-precision temperature measurement system according to claim 1, characterized in that: It also includes a compensation module (40), which is connected to the signal processing module (30) and is used to detect the ambient temperature of the high-precision temperature measurement system and transmit the compensation parameters corresponding to the ambient temperature to the signal processing module (30).

5. The high-precision temperature measurement system according to claim 1, characterized in that: The digital signal processing unit (32) stores segmented interval data of the target temperature zone and polynomial coefficients corresponding to each segmented interval; the polynomial coefficients are generated by comparing the standard calibration signal output by the calibration unit (12) with the theoretical value; the digital signal processing unit (32) determines the segmented interval according to the input digital signal and calls the corresponding polynomial coefficients to correct the digital signal.

6. The high-precision temperature measurement system according to claim 1, characterized in that: The excitation current output by the excitation module (20) is 100nA-1mA.

7. The high-precision temperature measurement system according to any one of claims 1-6, characterized in that: It also includes an interaction module, which is connected to the signal processing module (30) and includes: a multi-machine interconnection unit (50) for cascading and networking with other temperature measurement systems through a bus interface; a display unit (60) for displaying measurement parameters; and an external communication unit (70) for data interaction with a host computer or an external control system.

8. A high-precision temperature measuring device, characterized in that: The system includes a housing and a high-precision temperature measurement system as described in any one of claims 1-7, integrated into the housing.

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