Anti-corrosion wide temperature pressure data adaptive acquisition system for intelligent sensor

Abstract

This invention relates to the field of intelligent sensors and data acquisition technology, specifically to a corrosion-resistant, wide-temperature, pressure data adaptive acquisition system for intelligent sensors. The system includes a corrosion-resistant isolation component, a pressure sensor, a signal extraction circuit, a common-mode conditioning circuit, a sampling frequency calculation unit, a clock generation circuit, a clock protection circuit, an analog-to-digital converter (ADC), and a data output unit. External medium pressure is transmitted to a pressure-sensitive Wheatstone bridge via an isolation diaphragm and filling fluid. Differential-mode pressure and common-mode voltage signals are extracted. The common-mode voltage signal generates a temperature value. The target sampling frequency is determined based on the temperature value and a preset temperature-to-cutoff frequency correspondence. The clock generation circuit generates a sampling clock. The clock protection circuit outputs a backup sampling clock and a status flag when the frequency exceeds a preset range. The ADC completes sampling and outputs a pressure digital sequence. The data output unit packages the time information, sampling frequency information, status flag, and pressure digital sequence to output pressure data.

Description

Technical Field

[0001] This invention relates to the field of intelligent sensors and data acquisition technology, specifically to a corrosion-resistant, wide-temperature and pressure adaptive data acquisition system for intelligent sensors. Background Technology

[0002] With the increasing prevalence of highly corrosive media, high temperature fluctuations, and wide-temperature operating conditions in chemical processes, pressure measurement points installed in reactors, pipeline networks, and other locations place stringent technical demands on the stability, adaptability, and continuity of the data acquisition system. Especially in corrosion-resistant pressure detection scenarios, pressure signals not only need to be isolated from the medium and transmitted through an isolation structure, but also require maintaining the reliability of the sampling process and output data under wide-temperature conditions. Therefore, how to achieve adaptive acquisition of pressure data in a wide-temperature environment under corrosion-resistant isolation conditions has become a problem that needs to be solved in related technical fields. Traditional pressure data acquisition methods currently rely primarily on the following approaches: acquiring pressure signals using a fixed sampling frequency, obtaining ambient or device temperature through an independent temperature sensor, and simply shutting down or issuing a simple alarm in case of clock anomalies. However, fixed sampling frequencies, independent temperature detection, and simple clock anomaly handling all have certain drawbacks. For example, fixed sampling frequencies are difficult to adapt to the dynamic response differences caused by temperature variations in the isolation diaphragm, filling fluid, and sensor mechanical transmission bandwidth; independent temperature detection increases system complexity and results in insufficient consistency between temperature information and the pressure sampling link; and simply shutting down or issuing an alarm in case of clock anomalies can easily lead to sampling interruptions, making it difficult to continuously output pressure data with time information and status indicators under abnormal operating conditions. Summary of the Invention

[0003] This invention provides a corrosion-resistant, wide-temperature, adaptive pressure data acquisition system for intelligent sensors, addressing the technical shortcomings of existing pressure data acquisition methods in handling dynamic response adaptation and clock anomalies under wide-temperature conditions. The objective of this invention can be achieved through the following technical solutions: A corrosion-resistant, wide-temperature, pressure-adaptive data acquisition system for intelligent sensors includes: a corrosion-resistant isolation component, comprising an isolation diaphragm made of corrosion-resistant material and a filling fluid, for transmitting external medium pressure to a pressure sensor physically coupled to the corrosion-resistant isolation component; the pressure sensor includes a pressure-sensitive Wheatstone bridge for outputting differential-mode pressure signals and common-mode voltage signals; The signal extraction circuit is used to extract the differential mode pressure signal and output it to the analog-to-digital converter, and to extract the common mode voltage signal and output it to the common mode conditioning circuit; the common mode conditioning circuit is used to generate a temperature value based on the common mode voltage signal; the sampling frequency calculation unit is used to determine the target sampling frequency based on the temperature value and a preset temperature-to-cutoff frequency correspondence. The clock generation circuit is used to generate a sampling clock according to the target sampling frequency, and has a built-in backup clock source to generate a backup sampling clock output to the clock protection circuit; the clock protection circuit is used to limit the frequency range of the sampling clock, and when the frequency of the sampling clock exceeds the preset range, it switches and outputs the backup sampling clock of the backup clock source, and outputs a status flag. The analog-to-digital converter is used to sample the differential pressure signal according to the sampling clock or the backup sampling clock and output a pressure digital sequence; the data output unit is used to generate time information based on the accumulated sampling count, obtain sampling frequency information, receive the status flag output by the clock protection circuit, and package the time information, the sampling frequency information, the status flag and the pressure digital sequence to output pressure data.

[0004] Preferably, the corrosion-resistant isolation component further includes a filling fluid cavity and an internal encapsulation support structure; the isolation diaphragm is made of tantalum, Hastelloy, or Monel alloy; and the filling fluid is a perfluoropolyether fluorinated oil or a high-temperature resistant, low-volatility silicone oil.

[0005] Preferably, the signal extraction circuit includes an instrumentation amplifier and a passive resistor network; the instrumentation amplifier is used to amplify the differential-mode pressure signal to obtain a pressure sampling analog input; the pressure-sensitive Wheatstone bridge has two output nodes, and the passive resistor network is used to extract the common-mode voltage signal based on the voltage of the two output nodes.

[0006] Preferably, the common-mode conditioning circuit includes a buffer unit, an excitation normalization unit, and a low-pass filter unit; the excitation normalization unit is used to normalize the common-mode voltage signal according to a preset bridge excitation voltage to obtain a normalized common-mode voltage; the low-pass filter unit is used to smooth the normalized common-mode voltage to obtain a filtered common-mode voltage; the common-mode conditioning circuit is also used to generate a temperature value according to the filtered common-mode voltage and a preset temperature calibration relationship.

[0007] Preferably, the low-pass filter unit is used to smooth the normalized common-mode voltage according to a preset smoothing factor, wherein the preset smoothing factor ranges from 0.85 to 0.98.

[0008] Preferably, the sampling frequency calculation unit is used to obtain the sensor mechanical cutoff frequency by querying the preset temperature-cutoff frequency correspondence based on the temperature value, and to determine the target sampling frequency based on the sensor mechanical cutoff frequency according to the preset bandwidth matching ratio, wherein the preset bandwidth matching ratio ranges from 2.2 to 3.2.

[0009] Preferably, the sampling frequency calculation unit is used to limit the target sampling frequency between a preset minimum sampling frequency and a preset maximum sampling frequency to obtain a set sampling frequency.

[0010] Preferably, the clock generation circuit includes a mapping control unit, a digital-to-analog converter, a voltage-controlled oscillator (VCO), a Schmitt trigger shaper, and a frequency divider. The mapping control unit determines a digital control voltage value based on the set sampling frequency through a preset voltage-frequency control curve, converts it into an analog control voltage via the VCO, and then sends it to the VCO. The VCO outputs an oscillation frequency signal based on the control voltage. The Schmitt trigger shaper shapes the oscillation frequency signal, and the frequency divider divides the shaped signal according to a division factor and outputs a sampling clock.

[0011] Preferably, the clock protection circuit includes a detection divider, a counter, and a window comparator for detecting the frequency of the sampling clock; the clock protection circuit is also configured with a time reference unit for providing a preset window period for the counter and a preset counting period for the recovery confirmation process; When the frequency of the sampling clock deviates from the set sampling frequency by more than a preset allowable frequency deviation, the clock protection circuit is used to switch to the backup sampling clock and output a status flag; the preset allowable frequency deviation is a fixed percentage deviation relative to the set sampling frequency, and the frequency of the backup sampling clock is a preset safe sampling frequency.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. This system extracts differential-mode pressure signal and common-mode voltage signal simultaneously from a pressure-sensitive Wheatstone bridge, and converts the common-mode voltage into a temperature value after buffering, normalization, and low-pass smoothing. This ensures that the temperature acquisition is consistent with the pressure sampling link, avoiding the structural complexity and inconsistency problems caused by relying on independent temperature sensors. 2. This system adaptively determines the target sampling frequency based on the relationship between temperature and cutoff frequency, and forms a set sampling frequency within the upper and lower limits. This allows the sampling frequency to be adjusted synchronously with the temperature changes of the isolation structure and transmission bandwidth, thereby improving the acquisition adaptability under wide temperature conditions. 3. This system uses a clock generation circuit and a clock protection circuit to work together. When the sampling clock goes out of bounds, it automatically switches to a backup sampling clock and outputs a status flag. Combined with a recovery confirmation and hold mechanism, it reduces sampling interruptions under abnormal conditions. The data output unit synchronously packages time information, sampling frequency information, status flags, and pressure digital sequences, so that the sampling process, clock switching process, and pressure data correspond one-to-one, which facilitates subsequent recording, identification, and processing. This improves the continuity, reliability, and traceability of data at corrosion-resistant pressure measurement points under wide temperature conditions. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the functional modules of the corrosion-resistant wide-temperature and pressure adaptive data acquisition system for intelligent sensors according to this application. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0015] like Figure 1 As shown, a corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors includes: The corrosion-resistant isolation assembly includes an isolation diaphragm made of corrosion-resistant material and a filling fluid for transmitting external medium pressure to a pressure sensor physically coupled to the corrosion-resistant isolation assembly; the pressure sensor includes a pressure-sensitive Wheatstone bridge for outputting differential-mode pressure signals and common-mode voltage signals; The signal extraction circuit is used to extract the differential mode pressure signal and output it to the analog-to-digital converter described later, and to extract the common mode voltage signal and output it to the common mode conditioning circuit described later; the common mode conditioning circuit is used to generate a temperature value based on the common mode voltage signal. The sampling frequency calculation unit is used to determine the target sampling frequency based on the temperature value and the preset temperature-to-cutoff frequency correspondence. The clock generation circuit is used to generate a sampling clock according to the target sampling frequency, and has a built-in backup clock source to generate a backup sampling clock output to the clock protection circuit described later; the clock protection circuit is used to limit the frequency range of the sampling clock, and when the frequency of the sampling clock exceeds the preset range, it switches and outputs the backup sampling clock of the backup clock source, and outputs a status flag. An analog-to-digital converter is used to sample differential pressure signals according to a sampling clock or a backup sampling clock and output a digital pressure sequence. The data output unit is used to generate time information based on the accumulated sampling count, obtain sampling frequency information, receive the status flag output by the clock protection circuit, and package the time information, sampling frequency information, status flag and pressure digital sequence to output pressure data.

[0016] The corrosion-resistant isolation assembly also includes a filling fluid cavity and an internal encapsulation support structure; the isolation diaphragm is made of tantalum, Hastelloy, or Monel alloy; the filling fluid is a perfluoropolyether fluorinated oil or a high-temperature resistant, low-volatility silicone oil.

[0017] The signal extraction circuit includes an instrumentation amplifier and a passive resistor network; the instrumentation amplifier is used to amplify the differential-mode pressure signal to obtain the pressure sampling analog input; the piezoresistive Wheatstone bridge has two output nodes, and the passive resistor network is used to extract the common-mode voltage signal based on the voltage of the two output nodes.

[0018] The system is installed at corrosion-resistant pressure measuring points in high-pressure reactors and their transmission pipeline networks in fluorochemical industries. The external medium pressure is first borne by the isolation diaphragm and then transmitted through the filling liquid to the pressure-sensitive Wheatstone bridge inside the pressure sensor. Under the pressure, the bridge generates a differential-mode pressure signal and a common-mode voltage signal under the premise of stable bridge excitation. The differential-mode pressure signal is sent to the analog-to-digital converter through the signal extraction circuit, while the common-mode voltage signal is sent to the common-mode conditioning circuit for calculating the temperature value. After the temperature value enters the sampling frequency calculation unit, it is matched with the preset temperature and cutoff frequency correspondence to obtain the target sampling frequency under the current operating condition; the clock generation circuit generates a sampling clock based on the target sampling frequency and provides it to the analog-to-digital converter; if the sampling clock frequency exceeds the preset range, the clock protection circuit switches to the backup clock source to output the backup sampling clock, and at the same time gives a status flag. The analog-to-digital converter (ADC) samples the differential pressure signal to form a pressure digital sequence. The data output unit accumulates the sampling count to form time information and outputs the time information, sampling frequency information, status flag, and pressure digital sequence together for subsequent recording and processing. When the data output unit outputs a data packet corresponding to a pressure digital sequence, it first reads the currently used sampling clock source and the current sampling frequency value, then accumulates the sampling count once, and generates time information according to the correspondence between the current accumulated sampling points and the current sampling frequency. When the sampling path switches from the normal sampling clock to the backup sampling clock or reverts from the backup sampling clock to the normal sampling clock, the data output unit continues to accumulate time information using the current sampling frequency after the switch takes effect, starting from the first sampling point where the switch takes effect. At the same time, the status flag corresponding to that sampling point is written into the same data packet. Thus, the pressure digital sequence, time information, sampling frequency information, and status flag maintain a consistent correspondence in the output order. When corrosive components are present in the external medium of the reactor, the corrosion-resistant isolation component undertakes the functions of pressure transmission and medium isolation; the isolation diaphragm can be made of tantalum, Hastelloy, or Monel alloy, and the filling fluid can be made of perfluoropolyether fluorinated oil or high-temperature resistant low-volatility silicone oil to maintain the stability of the pressure transmission link; the internal encapsulation support structure is used to limit the relative displacement of components in the cavity and avoid abnormal disturbance of the filling fluid under wide temperature conditions. During signal extraction, the instrumentation amplifier amplifies the differential pressure signal to form a pressure sampling analog input suitable for the analog-to-digital converter. The passive resistor network extracts the common-mode voltage signal from the two output nodes of the bridge and sends it to the subsequent conditioning channel. If the common-mode voltage deviates briefly due to changes in bridge excitation or external interference, the subsequent clock protection circuit can switch to the backup sampling clock when the sampling clock goes out of bounds, thereby avoiding interruption of pressure data sampling. In this embodiment, the common-mode conditioning circuit includes a buffer unit, an excitation normalization unit, and a low-pass filter unit. The excitation normalization unit is used to normalize the common-mode voltage signal according to a preset bridge excitation voltage to obtain a normalized common-mode voltage. The calculation relationship is as follows: ,in, Represents the normalized common-mode voltage. Indicates common-mode voltage signal. Indicates the current bridge circuit excitation voltage. The reference voltage constant is preset; the low-pass filter unit is used to smooth the normalized common-mode voltage to obtain the filtered common-mode voltage; the common-mode conditioning circuit is also used to generate a temperature value based on the filtered common-mode voltage and the preset temperature calibration relationship.

[0019] The low-pass filter unit is used to smooth the normalized common-mode voltage according to a preset smoothing factor. Its recursive update calculation model is as follows: ,in, This is the filtered common-mode voltage for the current cycle. This is the filtered common-mode voltage from the previous cycle. This is the normalized common-mode voltage for the current cycle. The preset smoothing factor has a value range of 0.85 to 0.98.

[0020] The sampling frequency calculation unit is used to obtain the sensor's mechanical cutoff frequency by querying a preset temperature-cutoff frequency correspondence based on the temperature value, and to determine the target sampling frequency according to a preset bandwidth matching ratio based on the sensor's mechanical cutoff frequency. The determination relationship is as follows: ,in, For the target sampling frequency, The mechanical cutoff frequency of the sensor. The preset bandwidth matching ratio is set to a value ranging from 2.2 to 3.2.

[0021] When the anti-corrosion isolation structure and pressure sensor are in a wide temperature range for a long time, the common-mode voltage will be affected by the combined effects of bridge circuit excitation fluctuations, temperature changes and environmental interference. If the original common-mode voltage is directly used for subsequent conversion, the temperature value will fluctuate unexpectedly, affecting the generation of the target sampling frequency. Therefore, the common-mode conditioning circuit first isolates the bridge output node with high input impedance through a buffer unit, and then the excitation normalization unit performs normalization processing based on the preset bridge excitation voltage to decouple the common-mode voltage from the excitation conditions. The preset bridge excitation voltage is the reference excitation value used during system calibration. The normalization processing is used to convert the currently extracted common-mode voltage to the equivalent common-mode quantity under the reference excitation conditions. The normalized common-mode voltage can be expressed as the ratio of the current common-mode voltage to the bridge excitation voltage. The excitation normalization unit pre-sets the excitation effective range, and the lower limit of the excitation effective range is the minimum effective excitation value greater than zero. When the bridge excitation voltage is lower than the lower limit, zero, or missing, it does not regenerate a new normalization result, but retains the effective normalized common-mode voltage generated in the previous cycle and sends the retained result to the low-pass filter unit. When the bridge excitation voltage reaches the lower limit and is within the effective range, the excitation normalization unit reads the current common-mode voltage and the corresponding bridge excitation voltage in a fixed order in each sampling update cycle, and then performs normalization according to the normalization rules. Calculate the normalized common-mode voltage, where The preset reference voltage constant makes Maintain the voltage dimension, and Represents the normalized common-mode voltage. Indicates the current common-mode voltage. This indicates the current bridge circuit excitation voltage; the upper and lower limits of the effective excitation range can be preset according to the allowable fluctuation range of the bridge circuit power supply, so that the normalization process has consistent execution rules in each sampling period; The current common-mode voltage output by the buffer unit is first marked as a state to be normalized after entering the excitation normalization unit; when the excitation voltage of the bridge circuit in this cycle is within the effective range, the state to be normalized is converted into an effective normalized state and enters the low-pass filter unit. When the bridge excitation voltage is invalid in a given cycle, the state to be normalized is switched to a hold state. The low-pass filter unit reads the valid normalization result confirmed in the previous cycle and does not receive new normalization values. Thus, the common-mode voltage is not directly overwritten and updated in each cycle, but participates in subsequent processing in the order of the state to be normalized, the valid normalized state, and the hold state. This avoids sending invalid input directly into the temperature conversion path when the bridge excitation is momentarily abnormal. The low-pass filter unit smooths the normalized common-mode voltage to obtain the filtered common-mode voltage, and then generates the temperature value by combining it with the temperature calibration relationship. In this process, the low-pass filter unit operates according to the preset smoothing factor, and the value of the smoothing factor ranges from 0.85 to 0.98. The range of values ​​allows the common-mode conditioning circuit to maintain stable suppression of short-term disturbances while preserving the continuous trend brought about by temperature changes. If the smoothing factor value is less than the lower limit of the range, the sampling frequency of the subsequent stage will change frequently with the short-term fluctuations of the common-mode voltage. If the value is greater than the upper limit of the range, the response time of the temperature change transmission to the sampling frequency calculation unit will increase. By limiting the range as described above, the temperature value can be kept in a state suitable for subsequent queries and calculations; the smoothing process maintains the monotonic continuity of output changes, making the sampling frequency adjustment caused by temperature changes gradual, avoiding back-and-forth switching of the cutoff frequency query result between adjacent entries due to instantaneous pulse interference; the smoothing process recursively updates the normalized common-mode voltage of the current cycle and the filtered common-mode voltage of the previous cycle, and its recursive update mathematical model is as follows: ,in, This is the filtered common-mode voltage for the current cycle. This is the filtered common-mode voltage from the previous cycle. This is the normalized common-mode voltage for the current cycle. Set as the preset smoothing factor; In the first effective cycle after the system is powered on, the first normalized common-mode voltage is directly used as the first filtered common-mode voltage. From the second effective cycle onwards, the filtering result of the previous cycle and the normalized result of the current cycle are recursively updated. If no new normalized common-mode voltage is generated in the current cycle, the low-pass filter unit continues to keep the filtered common-mode voltage of the previous cycle unchanged, thereby avoiding the introduction of new fluctuations into the temperature calibration relationship when the input is invalid. After receiving a new common-mode voltage in the current cycle, the low-pass filter unit first compares it with the common-mode voltage of the previous cycle. If the direction of change is opposite to the most recently confirmed direction of change, and the magnitude of change does not exceed the preset minimum update magnitude, the common-mode voltage of the previous cycle remains unchanged. A new common-mode voltage is only output when subsequent cycles maintain the same direction of change or when the magnitude of change in a single cycle exceeds the minimum update magnitude. The minimum update magnitude is defined as 5% to 10% of the boundary interval between adjacent intervals in the calibration table. ,in, For minimum update magnitude, constant ,and and These are the upper and lower boundary voltage values ​​of the corresponding interval, which are preset to ensure that the low-pass filter unit has a consistent jitter suppression rule near the boundary. The temperature calibration relationship is implemented using a calibration table stored in order of temperature range. Each entry in the calibration table contains at least one filtered common-mode voltage range and the temperature value corresponding to that range. After obtaining the filtered common-mode voltage, the common-mode conditioning circuit searches for a unique matching entry in the calibration table according to the range comparison order and outputs the temperature value corresponding to that entry. When the filtered common-mode voltage falls on the common boundary of two adjacent entries, it is incorporated into one of the entries according to the predefined boundary assignment rules, thus ensuring that the same input corresponds to only one temperature output. The filtered common-mode voltage intervals in the calibration table are arranged continuously in ascending order of value, and adjacent intervals only connect at the boundary points without overlapping. When the common-mode conditioning circuit looks up the table, it compares each entry in a fixed order from the start end to the end end of the interval. When the filtered common-mode voltage meets the interval condition of a certain entry, it stops the subsequent comparison and outputs the temperature value corresponding to that entry. When the filtered common-mode voltage is less than or equal to the lower limit of the minimum interval, the temperature value corresponding to the minimum interval is output; when it is greater than or equal to the upper limit of the maximum interval, the temperature value corresponding to the maximum interval is output. Furthermore, each entry in the temperature calibration relationship is pre-established in a monotonic correspondence manner, that is, when the filtered common-mode voltage changes continuously in the same direction, its corresponding temperature value is arranged in the same order of increasing or decreasing, so that when the filtered common-mode voltage crosses the boundary of adjacent intervals, it only enters the adjacent temperature entry, and there is no situation where the same filtered common-mode voltage interval corresponds to multiple temperature values ​​at the same time. When updating the calibration table, only the entire table entry group is replaced without temporarily inserting individual entries to maintain interval continuity and temperature mapping consistency; thus, a single-valued mapping relationship is formed between the filtered common-mode voltage and the temperature value. After obtaining the temperature value, the sampling frequency calculation unit further queries the correspondence between temperature and cutoff frequency to obtain the sensor's mechanical cutoff frequency. This sensor's mechanical cutoff frequency reflects the effective transmission bandwidth of the filling fluid and isolation structure at the current temperature. The sampling frequency calculation unit generates a target sampling frequency according to a preset bandwidth matching ratio. When the bandwidth matching ratio is between 2.2 and 3.2, the target sampling frequency can maintain a fixed proportional relationship with the sensor's mechanical cutoff frequency. Therefore, when the mechanical bandwidth decreases at low temperatures, the sampling frequency decreases accordingly; when the mechanical bandwidth increases at high temperatures, the sampling frequency increases accordingly. This correspondence is used to reflect the dynamic response changes of the isolation diaphragm, filling fluid, and cavity structure caused by temperature changes. Therefore, the adjustment of the sampling frequency is based on the bandwidth change of the mechanical transmission link, rather than the change in the pressure amplitude itself. The correspondence between temperature and cutoff frequency is stored in a calibration table arranged in order of temperature range. When querying, the sampling frequency calculation unit locates the corresponding range according to the current temperature value and reads the mechanical cutoff frequency of the sensor corresponding to that range. When the current temperature value falls between two adjacent calibration temperatures, the corresponding preset range result is selected according to the pre-set boundary assignment rules to ensure that the same temperature input corresponds to a unique cutoff frequency output. After obtaining the sensor's mechanical cutoff frequency, the sampling frequency calculation unit calculates the sampling frequency according to the target sampling frequency. With sensor mechanical cutoff frequency The fixed proportional relationship between them Generate the target sampling frequency, where, For the target sampling frequency, The mechanical cutoff frequency of the sensor. The preset bandwidth matching ratio is used. When using the lookup table method, the mechanical cutoff frequency of the sensor corresponding to the current temperature range is output first, and then a multiplication calculation is performed according to the preset bandwidth matching ratio. Thus, a data flow relationship with a defined order is formed between the temperature value, the sensor mechanical cutoff frequency, and the target sampling frequency. Furthermore, the sampling frequency calculation unit performs four steps in a fixed order within each update cycle: temperature validity verification, cutoff frequency lookup, multiplication, and result confirmation. When the temperature value is within the coverage range of the calibration table, the cutoff frequency lookup step is initiated. When the temperature value exceeds the coverage range or no new valid temperature value is obtained in the cycle, the new lookup step is skipped, and the sensor mechanical cutoff frequency already confirmed in the previous valid cycle is directly called to participate in the result confirmation. If a new temperature value and the previous valid sensor mechanical cutoff frequency appear simultaneously in the current cycle, the new sensor mechanical cutoff frequency obtained after looking up the table for the current cycle will be used first to ensure that the sampling frequency adjustment follows the update order of new first and old last. The temperature intervals in the temperature-cutoff frequency correspondence are arranged in a non-overlapping and continuous manner, and each interval corresponds to only one sensor mechanical cutoff frequency value. When the current temperature value is within a certain range, the mechanical cutoff frequency of the sensor corresponding to that range is directly read; when the current temperature value is exactly at the common boundary of adjacent ranges, it is assigned to only one range according to the pre-set boundary assignment rules, so as to avoid the same temperature value triggering two sets of cutoff frequency results; thus, the mapping from temperature value to sensor mechanical cutoff frequency and then to target sampling frequency is unique in each update cycle. If the entry corresponding to the temperature calibration relationship is missing, or the common-mode voltage is near the calibration boundary, the sampling frequency calculation unit uses the cutoff frequency corresponding to the previous valid temperature value to avoid a jump in the target sampling frequency. This processing method does not change the correspondence between temperature and cutoff frequency itself, but is only used to maintain the continuity of the sampling frequency generation process. The aforementioned previous valid temperature value refers to the temperature value corresponding to the most recent valid calibration query and successful acquisition of the sensor's mechanical cutoff frequency. In this embodiment, the sampling frequency calculation unit is used to limit the target sampling frequency between a preset minimum sampling frequency and a preset maximum sampling frequency to obtain the set sampling frequency.

[0022] The clock generation circuit includes a mapping control unit, a digital-to-analog converter, a voltage-controlled oscillator (VCO), a Schmitt trigger shaper, and a frequency divider. The mapping control unit determines the digital control voltage value by mapping it to a preset voltage-frequency control curve according to the set sampling frequency, and converts it into an analog control voltage via the digital-to-analog converter before sending it to the VCO. The VCO outputs an oscillation frequency signal according to the control voltage. The Schmitt trigger shaper shapes the oscillation frequency signal, and the frequency divider divides the shaped signal according to the division coefficient and outputs the sampling clock.

[0023] The clock protection circuit includes a detection divider, a counter, and a window comparator for detecting the frequency of the sampling clock; the clock protection circuit is also equipped with a time reference unit for providing a preset window period for the counter and a preset counting period for the recovery confirmation process; When the frequency of the sampling clock deviates from the set sampling frequency by more than the preset allowable frequency deviation, the clock protection circuit switches to the backup sampling clock and outputs a status flag; the preset allowable frequency deviation is set relative to the set sampling frequency. ±5%, that is, the judgment interval is The frequency of the backup sampling clock is a preset safe sampling frequency, which is the arithmetic mean of the preset minimum sampling frequency and the preset maximum sampling frequency.

[0024] After obtaining the target sampling frequency, the sampling frequency calculation unit does not directly send it to the clock generation circuit. Instead, it first limits it between the preset minimum sampling frequency and the preset maximum sampling frequency to form the set sampling frequency. The limiting operation is used to constrain the sampling frequency under extreme conditions within the range allowed by the analog-to-digital converter sampling capability and system power consumption. If the target sampling frequency is lower than the minimum sampling frequency, the minimum sampling frequency will be used. If the sampling frequency is higher than the maximum sampling frequency, the maximum sampling frequency will be used. To ensure a definite execution order for this limiting process, the sampling frequency calculation unit compares the target sampling frequency with the preset minimum sampling frequency and then with the preset maximum sampling frequency after obtaining the target sampling frequency each time. When the target sampling frequency is greater than or equal to the lower limit and less than or equal to the upper limit, it is directly used as the set sampling frequency output. When the target sampling frequency is less than the lower limit, the lower limit value is output as the set sampling frequency. When the target sampling frequency is greater than the upper limit, the upper limit value is output as the set sampling frequency. Thus, any target sampling frequency input corresponds to a unique set sampling frequency output. The clock generation circuit generates a sampling clock based on the set sampling frequency; the voltage-controlled oscillator first outputs an oscillation frequency signal according to the control voltage, the Schmitt trigger shapes the oscillation frequency signal, and the frequency divider outputs the final sampling clock according to the division coefficient; the control voltage is determined by mapping the set sampling frequency through a preset voltage-frequency control curve, so when the set sampling frequency changes, the control voltage is adjusted synchronously, and the sampling clock output by the clock generation circuit also changes accordingly. The frequency division coefficient is pre-configured based on the operating range and target output range of the voltage-controlled oscillator (VCO) to control the VCO to operate within the linear frequency response range. The frequency divider then outputs the required sampling clock, improving the consistency of the sampling clock adjustment process. The sampling frequency is set as the target frequency value output by the sampling frequency calculation unit and limited by upper and lower limits. The sampling clock is the clock signal actually generated by the clock generation circuit based on the set sampling frequency and sent to the analog-to-digital converter. In the entire text, these two correspond to the frequency setting result and the clock output result, respectively. The voltage-frequency control curve is pre-stored as a correspondence table arranged in order of frequency range. Each entry in the correspondence table contains at least the set sampling frequency range, the corresponding control voltage value, and the corresponding frequency division coefficient. After receiving the set sampling frequency, the clock generation circuit first looks up the range of the set sampling frequency in the correspondence table, then reads the preset control voltage value and frequency division coefficient of the range, and sends the read control voltage to the voltage-controlled oscillator and the read frequency division coefficient to the frequency divider. If the set sampling frequency happens to be located at the boundary of an adjacent interval, then according to the rule of left-closed and right-open intervals, the control parameters corresponding to the high-frequency interval with the boundary value as the lower limit are selected, so as to ensure that the same set sampling frequency corresponds to only one set of control voltage and frequency division coefficient; the set sampling frequency intervals in the corresponding table are arranged in ascending order of value, and the beginning and end of each interval are continuous and do not overlap; the clock generation circuit compares item by item in a fixed order from low frequency interval to high frequency interval. When the set sampling frequency falls into a certain interval, the comparison stops and the control voltage value and frequency division coefficient corresponding to that interval are output; When the set sampling frequency is lower than the minimum range, the control parameters corresponding to the minimum range are used; when it is higher than the maximum range, the control parameters corresponding to the maximum range are used. Thus, the control path between the set sampling frequency and the control voltage and the frequency division coefficient has a definite input-output relationship. Furthermore, after receiving a new set sampling frequency, the clock generation circuit does not immediately interrupt the current output, but first keeps the current sampling clock valid, and then loads the new control voltage value and frequency division coefficient at the boundary of the next frequency division output cycle. Once the new control parameters have been loaded, the voltage-controlled oscillator and frequency divider are allowed to enter the next sampling cycle according to the new parameters. This avoids the generation of missing or repeated pulses due to rewriting the control parameters in the middle of the cycle, and keeps the switching from the set sampling frequency to the sampling clock unidirectional. If multiple consecutive update cycles arrive without a change in the set sampling frequency, the clock generation circuit maintains the current control voltage value and the frequency division coefficient unchanged, and does not repeatedly trigger the parameter loading process. The backup clock source outputs a preset safe sampling frequency during system initialization and is connected to the switching port of the clock protection circuit via an independent clock path. Under normal sampling conditions, the backup clock source remains in a ready-to-switch state and does not participate in the analog-to-digital converter counting. Only when the clock protection circuit outputs a switching command is the backup clock source sent to the analog-to-digital converter as the current sampling clock source. Thus, both the normal sampling path and the backup sampling path are clock-ready before switching, avoiding sampling interruptions caused by restarting the backup clock after an anomaly occurs. To prevent the sampling clock from deviating from the set sampling frequency, the clock protection circuit continuously detects the sampling clock frequency through a detection divider, a counter, and a window comparator. The detection divider converts the sampling clock into countable detection beats, the counter counts the number of pulses of the detection beats within a preset window period, and then the window comparator compares the count with the allowable range corresponding to the set sampling frequency to obtain the actual frequency deviation. The actual frequency deviation can be expressed as the ratio of the absolute value of the difference between the sampling clock frequency and the set sampling frequency to the set sampling frequency. When this deviation exceeds the preset allowable frequency deviation, the clock protection circuit switches to the backup sampling clock and outputs a status flag. The frequency of the backup sampling clock is the preset safe sampling frequency, which is suitable for situations such as clock loss, frequency drift, or abnormal control voltage. The fixed percentage deviation is used to maintain a consistent tolerance judgment criterion under different set sampling frequencies, so that the window comparator can complete the out-of-bounds identification according to the same judgment logic. At the end of each detection window, the window comparator executes the out-of-bounds judgment logic in the following order: First, it calculates the lower and upper limits of the allowed frequency based on the currently set sampling frequency and the fixed percentage deviation. Then, it compares the sampling clock frequency obtained by the counter with the lower and upper limits of the allowed frequency. If the sampling clock frequency is greater than or equal to the lower limit of the allowed frequency and less than or equal to the upper limit of the allowed frequency, the current sampling clock is determined to be valid. If it is less than the lower limit of the allowed frequency or greater than the upper limit of the allowed frequency, the current sampling clock is determined to be out of bounds, and a switching command is output. The status flag includes at least a normal sampling state and a standby sampling state, which are used to characterize the clock source corresponding to the current pressure digital sequence. The status flag uses a one-bit binary code, where logic 0 represents the normal sampling state and logic 1 represents the standby sampling state. When the data output unit packages the output, it appends the status flag as the most significant bit to the beginning of the pressure data frame. The clock protection circuit is configured with four control states: normal monitoring state, out-of-bounds confirmation state, standby holding state, and recovery confirmation state. Under normal monitoring conditions, the window comparator performs an out-of-bounds determination on the statistical results of each detection window. When an out-of-bounds determination occurs for the first time, the control state switches to the out-of-bounds confirmation state. If the next detection window still remains out of bounds, a switching command is output and the system switches to the standby hold state. If the next detection window recovers to the allowable range, the out-of-bounds confirmation is canceled and the system returns to normal monitoring conditions. After entering the standby hold state, the sampling clock source of the analog-to-digital converter is switched to the standby sampling clock. At the same time, the original sampling clock continues to be detected but no longer directly participates in sampling. Only when multiple consecutive detection windows determine that the original sampling clock has returned to the allowable range will the control state change from the standby hold state to the recovery confirmation state. After the recovery confirmation state reaches the preset counting period, the standby sampling clock is canceled and the normal sampling path is restored. If an out-of-bounds error occurs again during the recovery confirmation process, the system will return to the standby hold state. Therefore, the clock protection circuit uses different state conditions for boundary crossing, switching, holding, and recovery to avoid a single window result directly triggering round-trip switching. Furthermore, after the detection window ends, the switching command takes effect based on the boundary of the internal independent clock or backup sampling clock provided by the time reference unit. The analog-to-digital converter is forced to use the switched clock source from the first working cycle after this boundary. In the current detection window before the switching command takes effect, the data output unit keeps a record of the clock source currently in use and updates the status flag from the first sampling point where the switching takes effect. When restoring the normal sampling path, the same boundary switching rule is also followed, so that the status flag change points, sampling clock source change points, and pressure digital sequence corresponding points are consistent in time sequence. If the sampling clock is within the allowable deviation range, the clock protection circuit maintains the current sampling path and does not switch; if the deviation continues to increase, the status flag is output along with the backup sampling clock for the data output unit to record; thus, the pressure digital sequence can continue to be generated under abnormal clock conditions, and the corresponding status flag is retained in the data packet, which is convenient for subsequent identification of whether the data segment is in a safe sampling state. To avoid repeated switching of the sampling path near the critical frequency, the clock protection circuit maintains the sampling path after switching to the backup sampling clock until the recovered sampling clock is detected to have returned to the allowable deviation range and remained stable for a preset counting period before restoring the original sampling path. The preset counting period is used to continuously confirm the stability of the recovered sampling clock. Its counting reference is provided by the detection beat output by the detection divider. The counter continuously counts whether the sampling clock always meets the allowable deviation requirement within this counting period. Only when the requirement is met throughout the entire counting period will the window comparator output the recovery judgment result. After switching to the backup sampling clock, the clock protection circuit maintains the status flag as backup sampling state. Only when multiple consecutive detection windows determine that the sampling clock has fallen back into the allowable frequency range and has reached the preset counting period will the switching command be revoked and the normal sampling state be restored. Thus, the switching conditions, holding conditions and recovery conditions of the clock protection circuit are distinguished from each other in the control flow, avoiding back-and-forth switching due to short-term jitter within a single detection window. The analog-to-digital converter samples the differential pressure signal according to the sampling clock or the backup sampling clock, and outputs the pressure digital sequence along with time information, sampling frequency information and status flags; thus, the system can maintain pressure data acquisition under wide temperature and corrosion conditions and retain the necessary records during the sampling clock change process.

[0025] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors, characterized in that: include: The corrosion-resistant isolation assembly includes an isolation diaphragm made of corrosion-resistant material and a filling fluid for transmitting external medium pressure to a pressure sensor physically coupled to the corrosion-resistant isolation assembly; the pressure sensor includes a pressure-sensitive Wheatstone bridge for outputting differential-mode pressure signals and common-mode voltage signals; The signal extraction circuit is used to extract the differential mode pressure signal and output it to the analog-to-digital converter, and to extract the common mode voltage signal and output it to the common mode conditioning circuit. A common-mode conditioning circuit is used to generate a temperature value based on the common-mode voltage signal; The sampling frequency calculation unit is used to determine the target sampling frequency based on the temperature value and the preset temperature-to-cutoff frequency correspondence. A clock generation circuit is used to generate a sampling clock according to the target sampling frequency, and has a built-in backup clock source to generate a backup sampling clock output to the clock protection circuit; A clock protection circuit is used to limit the frequency range of the sampling clock, and when the frequency of the sampling clock exceeds the preset range, to switch and output the backup sampling clock of the backup clock source, and output a status flag. An analog-to-digital converter is used to sample the differential pressure signal according to the sampling clock or the backup sampling clock, and output a pressure digital sequence; The data output unit is used to generate time information based on the accumulated sampling count, obtain sampling frequency information, receive the status flag output by the clock protection circuit, and package the time information, the sampling frequency information, the status flag and the pressure digital sequence to output pressure data.

2. The corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors according to claim 1, characterized in that, The corrosion-resistant isolation component also includes a filling fluid cavity and an internal encapsulation support structure; the isolation diaphragm is made of tantalum, Hastelloy, or Monel alloy; the filling fluid is a perfluoropolyether fluorinated oil or a high-temperature resistant, low-volatility silicone oil.

3. The corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors according to claim 1, characterized in that, The signal extraction circuit includes an instrumentation amplifier and a passive resistor network; the instrumentation amplifier is used to amplify the differential-mode pressure signal to obtain a pressure sampling analog input; the piezoresistive Wheatstone bridge has two output nodes, and the passive resistor network is used to extract the common-mode voltage signal based on the voltage of the two output nodes.

4. The corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors according to claim 1, characterized in that, The common-mode conditioning circuit includes a buffer unit, an excitation normalization unit, and a low-pass filter unit. The excitation normalization unit is used to normalize the common-mode voltage signal according to a preset bridge excitation voltage to obtain a normalized common-mode voltage. The low-pass filter unit is used to smooth the normalized common-mode voltage to obtain a filtered common-mode voltage. The common-mode conditioning circuit is also used to generate a temperature value according to the filtered common-mode voltage and a preset temperature calibration relationship.

5. The corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors according to claim 4, characterized in that, The low-pass filter unit is used to smooth the normalized common-mode voltage according to a preset smoothing factor, the preset smoothing factor being in the range of 0.85 to 0.

98.

6. The corrosion-resistant, wide-temperature, and pressure-adaptive data acquisition system for intelligent sensors according to claim 1, characterized in that, The sampling frequency calculation unit is used to query the preset temperature-cutoff frequency correspondence based on the temperature value to obtain the sensor mechanical cutoff frequency, and to determine the target sampling frequency based on the sensor mechanical cutoff frequency according to the preset bandwidth matching ratio. The preset bandwidth matching ratio ranges from 2.2 to 3.

2.

7. The corrosion-resistant, wide-temperature, pressure-adaptive data acquisition system for intelligent sensors according to claim 6, characterized in that, The sampling frequency calculation unit is used to limit the target sampling frequency between a preset minimum sampling frequency and a preset maximum sampling frequency to obtain the set sampling frequency.

8. The corrosion-resistant, wide-temperature, pressure-adaptive data acquisition system for intelligent sensors according to claim 7, characterized in that, The clock generation circuit includes a mapping control unit, a digital-to-analog converter, a voltage-controlled oscillator (VCO), a Schmitt trigger shaper, and a frequency divider. The mapping control unit determines a digital control voltage value based on the set sampling frequency through a preset voltage-frequency control curve, converts it into an analog control voltage via the VCO, and then sends it to the VCO. The VCO outputs an oscillation frequency signal based on the control voltage. The Schmitt trigger shaper shapes the oscillation frequency signal, and the frequency divider divides the shaped signal according to a division factor and outputs the sampling clock.

9. The corrosion-resistant wide-temperature and pressure data adaptive acquisition system for intelligent sensors according to claim 7, characterized in that, The clock protection circuit includes a detection divider, a counter, and a window comparator, used to detect the frequency of the sampling clock; The clock protection circuit is also equipped with a time reference unit, which is used to provide a preset window period for the counter and a preset counting period for the recovery confirmation process; When the frequency of the sampling clock deviates from the set sampling frequency by more than a preset allowable frequency deviation, the clock protection circuit is used to switch to the backup sampling clock and output a status flag; the preset allowable frequency deviation is a fixed percentage deviation relative to the set sampling frequency, and the frequency of the backup sampling clock is a preset safe sampling frequency.

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