CN117433661A - Numerical control platinum resistance simulation test system and method based on four-wire sampling - Google Patents
Numerical control platinum resistance simulation test system and method based on four-wire sampling Download PDFInfo
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- CN117433661A CN117433661A CN202311284488.0A CN202311284488A CN117433661A CN 117433661 A CN117433661 A CN 117433661A CN 202311284488 A CN202311284488 A CN 202311284488A CN 117433661 A CN117433661 A CN 117433661A
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 title claims abstract description 229
- 229910052697 platinum Inorganic materials 0.000 title claims abstract description 116
- 238000004088 simulation Methods 0.000 title claims abstract description 74
- 238000005070 sampling Methods 0.000 title claims abstract description 38
- 238000012360 testing method Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 10
- 238000005259 measurement Methods 0.000 claims abstract description 57
- 238000012546 transfer Methods 0.000 claims abstract description 39
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 230000003750 conditioning effect Effects 0.000 claims description 5
- 238000010998 test method Methods 0.000 claims description 3
- 230000006870 function Effects 0.000 description 10
- 238000009529 body temperature measurement Methods 0.000 description 8
- 238000013461 design Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000013500 data storage Methods 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000007405 data analysis Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Abstract
The invention discloses a numerical control platinum resistance simulation test system and method based on four-wire sampling. The platinum resistance simulation module is connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment through a calibration transfer box, and simulates a plurality of set load temperatures by controlling each path of resistance value output; the signal transfer and adjustment box transfers and adjusts each path of resistance signal into a signal which accords with the sampling of the 34980 measurement module; the calibration transfer box is used for controlling the on-off of the satellite thermal control equipment platinum resistance measurement acquisition circuit and the platinum resistance simulation module. The invention realizes accurate simulation of platinum resistance change and can ensure the temperature control requirement when the measurement requirement of the satellite thermal control equipment is highest.
Description
Technical Field
The invention relates to a numerical control platinum resistance simulation test system and method based on four-wire sampling, and belongs to the technical field of spacecraft thermal control tests.
Background
The satellite thermal control equipment is used as important equipment of a satellite thermal control subsystem, and plays an important role in providing a good temperature environment for other subsystems and equipment of the satellite and ensuring the normal operation of the subsystems and the equipment of the satellite. With the development of satellites, the whole satellite has higher requirements on the accuracy of temperature measurement and the stability of temperature measurement of a thermal control subsystem.
At present, the temperature measurement of the satellite thermal control equipment is generally realized by two-wire wiring. The two-wire system wiring mode is simple, but is influenced by the material, the length and the temperature environment of the lead, so that the temperature measurement precision is poor. In addition, in high-precision sampling, the suitability of the A/D chip is critical to the performance of the whole system. The conventional 16-bit successive approximation type A/D converter cannot meet the application requirements, and in order to effectively ensure the temperature measurement accuracy of +/-0.01 ℃ in the whole measurement range of +15 ℃ to +25 ℃, the A/D converter with higher performance is required.
The satellite thermal control subsystem consists of thermal control equipment, a heating plate, a thermistor and other accessories, wherein the temperature of the equipment is collected by the thermistor, the temperature value is transmitted to a single machine/module of the thermal control subsystem, and the heating plate is controlled to perform heating operation under certain conditions. Under the condition that the thermistor is not implemented in the whole satellite comprehensive test stage, the numerical value of the thermistor is simulated by using a simulated numerical control resistor load, so that the purposes of function and performance test are achieved. The high-resolution multimode comprehensive imaging satellite adopts a four-wire platinum resistor acquisition module, the platinum resistor is a high-precision thermistor, and a four-wire wiring (constant current source excitation) is adopted to eliminate measurement errors caused by lead resistors and external noise. The temperature measurement precision of the platinum resistor is required to reach 0.01 ℃, and the corresponding resistance value change range is about 4mΩ, so that the conventional numerical control resistor mode cannot be realized.
Disclosure of Invention
The invention solves the technical problems that: the system and the method for simulating the numerical control platinum resistance based on four-wire sampling are provided to overcome the defects of the prior art, and realize the function of simulating the platinum resistance of the satellite thermal control equipment.
The technical scheme of the invention is as follows:
a numerical control platinum resistance simulation test system based on four-wire sampling comprises a platinum resistance simulation module, a signal transfer adjustment box, a 34980 measurement module and a calibration transfer box;
the platinum resistance simulation module is connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment through the calibration transfer box, simulates a plurality of set load temperatures through controlling each path of resistance value output by the platinum resistance simulation module, and sends each path of resistance signal to the signal transfer and adjustment box;
the signal transfer and adjustment box transfers and adjusts each path of resistance signal into a signal which accords with the sampling of the 34980 measurement module;
the 34980 measurement module measures a signal output by the signal transfer conditioning box to obtain resistance information;
the calibration transfer box is used for controlling the on-off of the platinum resistance measurement acquisition circuit of the satellite thermal control equipment and the platinum resistance simulation module, and when a relay in the calibration transfer box is closed, the platinum resistance measurement acquisition circuit of the satellite thermal control equipment performs four-wire system sampling; when the relay is opened, the platinum resistance measurement acquisition circuit of the satellite thermal control equipment is disconnected with the platinum resistance simulation module.
Preferably, the platinum resistance simulation module comprises a simulation circuit and a control submodule of each channel;
each channel analog circuit comprises two digital control resistors and three resistors; the numerical control resistor Rx and the resistor R1 are connected in parallel, the numerical control resistor Ry and the resistor R2 are connected in parallel, and the two parallel branches are connected in series and then connected in series with the resistor R3 to be grounded; the output resistance of the analog circuit is:
the control submodule is used for controlling the resistance values of the numerical control resistor Rx and the numerical control resistor Ry in each channel simulation circuit, so that the resistance value output by each channel of the platinum resistor simulation module accurately simulates the set load temperature.
Preferably, the control submodule comprises a temperature amount and resistance amount conversion unit, a self-calibration unit, a configuration unit and a control unit;
the configuration unit receives the load temperature to be simulated of each channel input from the outside and sequentially forwards the load temperature to the temperature and resistance conversion unit;
the self-calibration unit calibrates the numerical control resistor in each channel analog circuit, sets one BIT for each time of the numerical control resistor, measures the BIT through a 34980 measurement module, and performs self-calibration according to the measurement result;
the temperature and resistance conversion unit converts the received temperature value into a corresponding resistance value according to the conversion relation:
R＝100[1+AT+BT 2 +CT 3 (T-100)]，T∈(-100,0)
R＝100[1+AT+BT 2 ]，T∈[0,50]
wherein T is the received temperature in degrees Celsius; r is an output resistance value, and is a unit omega; A. b, C is the resistivity;
according to the output resistor R to be obtained, the resistance values of the numerical control resistors Rx and Ry are obtained; the simulation of the set temperature is realized by setting the resistance values of the numerical control resistors Rx and Ry;
the control unit is used for inputting a temperature value to be simulated to the platinum resistance simulation module, checking the accuracy of the output resistance of the platinum resistance simulation module and controlling the on-off of the relay in the calibration transfer box.
Preferably, the control unit controls the method, including:
transmitting the simulated temperature value to the platinum resistance simulation module, judging the simulation accuracy of the platinum resistance simulation module according to the resistance value output by the 34980 measurement module, and outputting a prohibition instruction to the calibration transfer box if the simulation is determined to be inaccurate; and if the simulation is determined to be accurate, outputting an enabling instruction to the calibration transfer box, and performing four-wire system sampling by the satellite thermal control equipment platinum resistance measurement acquisition circuit.
Preferably, the numerical control resistor Rx and the numerical control resistor Ry are numerical control resistors AD8403arz1 with the maximum resistance value of 1kΩ, and the resistors R1, R2 and R3 are 20Ω, 80Ω and 24Ω respectively; when the numerical control resistor Rx and the numerical control resistor Ry are changed, the resistance change range of the analog circuit output is 65.000 omega-120.158 omega.
Preferably, the 34980 measurement module has 6-bit half precision, 8 34925 measurement modules are configured, the 34925 measurement module is a 40/80 channel optically isolated FET multiplexer, the supporting input voltage range is + -80V, the scanning channel reaches 1000 channels/sec, and the configuration is realized in a single-line, double-line or 4-line mode.
Preferably, the resistance values of the numerical control resistors Rx and Ry in the temperature and resistance conversion unit and the corresponding simulated temperatures are tabulated, and the relation between the resistors and the temperatures is directly obtained through table lookup.
Preferably, the control submodule further comprises a file importing unit, temperature values set by the channels are written into files, the files are imported and stored, and the configuration unit reads the temperatures of the channels and sends the temperatures to the temperature and resistance conversion unit.
A numerical control platinum resistance simulation test method based on four-wire sampling comprises the following steps:
according to a plurality of load temperatures to be simulated, calculating to obtain resistance values corresponding to the load temperatures respectively;
according to each resistance value, calculating to obtain the resistance value of the numerical control resistor in the corresponding analog circuit, and setting the numerical control resistor of each channel analog circuit in the platinum resistor analog module as the calculated resistance value;
the platinum resistance simulation module is connected into a satellite thermal control equipment platinum resistance measurement acquisition circuit through a calibration adapter box, and the satellite thermal control equipment platinum resistance measurement acquisition circuit carries out four-wire system sampling on the resistance output by each channel of the platinum resistance simulation module;
carrying out transfer conditioning on the resistance value signals output by the analog circuits of all channels, measuring by using a 34980 measuring module, comparing the obtained accurate resistance value with the calculated resistance value, and if the accurate resistance value exceeds a threshold value, calibrating the relay in the transfer box to be disconnected; otherwise, the satellite thermal control equipment platinum resistance measurement acquisition circuit continues four-wire sampling.
Preferably, before the platinum resistance simulation module is connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment through a calibration transfer box, the platinum resistance simulation module is self-calibrated, and the internal resistance of the module is calibrated to a zero position.
Compared with the prior art, the invention has the advantages that:
(1) The invention designs the parallel and serial simulation circuits of the adjustable resistors, and realizes the change of the simulated platinum resistor by adjusting the resistance value of the numerical control resistor, thereby ensuring the temperature control requirement when the measurement requirement of the satellite thermal control equipment is highest (20 ℃ +/-2 ℃).
(2) The four-wire sampling is performed by utilizing the measuring function of 34980, the measuring feedback output is performed, and the difficulty of four-wire sampling numerical control platinum resistance simulation is solved.
(3) According to the invention, the temperature drift problem of the numerical control resistor of the platinum resistor is solved by carrying out self-calibration feedback on specific output.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram of a thermal test device according to an embodiment of the present invention;
FIG. 2 is a block diagram of a platinum resistance simulation module according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an analog output circuit of a platinum resistor according to an embodiment of the present invention;
FIG. 4 is a four-wire sampling schematic diagram of a platinum resistor according to an embodiment of the present invention;
FIG. 5 is a flow chart showing the implementation of a platinum resistor simulation module according to an embodiment of the present invention;
FIG. 6 is a main control flow chart of a thermistor analog module according to an embodiment of the invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The invention provides a numerical control platinum resistance simulation test system based on four-wire sampling, which is shown in fig. 1 and comprises a signal transfer and adjustment box, a 34980 measurement module, a platinum resistance simulation module and a calibration transfer box.
The signal transfer and adjustment box is used for transferring and adjusting each path of signal into a signal conforming to the 34980 sampling, and the numerical control resistor calibration utilizes the measuring function of 34980 to carry out four-wire system sampling so as to achieve the purposes of measuring the numerical control resistor value and checking.
The platinum resistance simulation module is used for replacing a platinum resistance to be connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment under a precision resistance working mode, and simulating platinum resistance temperature change. Changing the output resistance of the analog platinum resistance simulation module, checking the function and precision of the temperature measuring loop, as shown in fig. 4, rt 1-RT 216 are variable resistors output by each channel of the platinum resistance simulation module, and are connected into four-wire circuits at the positive end and the negative end of a platinum resistance acquisition loop 2 of the satellite thermal control equipment, and the satellite thermal control equipment selects a sigma/delta analog-digital converter with more than 20 bits and an amplifier selected as an AD converter for integration, wherein the gain is 16, so that the temperature measuring precision of +/-0.01 ℃ is effectively ensured in the whole measuring range of +15 ℃ to +25 ℃, and differential amplification is carried out.
In order to meet the design requirement and verify the small current used in four-wire sampling of the platinum resistor, the platinum resistor simulation module adopts parallel and serial resistors to realize precise change, the working schematic diagram is shown in fig. 3, the numerical control resistor Rx and the resistor R1 are connected in parallel, the numerical control resistor Ry and the resistor R2 are connected in parallel, and the two parallel branches are connected in series and then connected in series with the resistor R3 to be grounded. By changing the values of the numerical control resistors Rx and Ry and changing the output resistance, the resistance variation represented by 0.01 degree is realized.
The output resistance is:
resistance selection in platinum resistance mode:
1) Numerical control resistor selection: the digital control resistor connected in parallel in the resistor bridge is required to have a small variation value as possible because of the resistance variation of 0.01 omega, and an ADI digital potentiometer AD8403ar1 is adopted to output the required resistor, wherein the resistance value is 1k omega, 256 tap resolution and the temperature coefficient is 500 ppm/DEG C.
2) Precision resistor selection: the other end of the resistor bridge is a precise metal film resistor. The RJ24A metal film fixed resistor of 718 factories is selected, and has the characteristics of small volume, high precision, small temperature coefficient, moisture resistance, heat resistance, stable and reliable resistance value and the like.
The adopted numerical control resistors Rx and Ry are 1kΩ numerical control resistors AD8403arz1, and the resistors R1, R2 and R3 are 20Ω, 80Ω and 24Ω respectively. When Rx and Ry are changed, and the final output resistance value change range is 65.000 omega-120.158 omega, the stepping minimum step length is different according to different Rx and Ry values. When the method is adopted for design, the temperature control requirement when the measurement requirement of the satellite thermal control equipment is highest (20 ℃ +/-2 ℃) can be ensured, and corresponding yield can be selected and selected in other temperature ranges.
The precision of the change of the platinum resistor is 4mΩ, but the temperature drift of the numerical control resistor used by the platinum resistor module is 500 ppm/DEG C, and when a table look-up method is adopted, the precision is affected by the temperature change, therefore, the measurement feedback output is carried out by using the 34980 measurement module as measurement, so as to realize the change of the quasi-platinum resistor. The 34980 measurement module has 6-bit half precision, and 8 34925 measurement modules are configured to measure the resistance subjected to switching conditioning. The 34925 measuring module is a 40/80 channel optical isolation FET multiplexer, can support an input voltage range of +/-80V, can scan channels of 1000 channels/second, can be configured into a single-wire, double-wire or 4-wire mode, and can be used for different measuring tasks.
And the calibration transfer box receives the control command, and performs the closing and opening control of the relay according to the requirement, so as to realize the output of switching the platinum resistor. When the output is enabled, a relay in the calibration transfer box is closed, so that four-wire sampling of the satellite thermal control equipment is performed; when the output is disabled, 4-wire sampling feedback is performed by the 34980 measurement module to provide a satisfactory high-precision thermal control resistance.
The function flow chart of the platinum resistance simulation module control submodule is shown in fig. 6, and the control submodule comprises a single-channel high-precision configuration unit, a batch configuration unit, a file importing unit, a self-checking unit, a self-calibration unit, a data storage unit, a relation unit between temperature T and resistance R, a test reading unit, an instruction processing unit, a communication unit, a return data analysis unit, a data display unit and a control unit, which are shown in fig. 2. Wherein each unit functions as follows:
single channel configuration unit: and selecting a single channel, setting a target value for the resistance value of the channel, and returning to the actual set value output by the hardware of the channel, wherein both values are displayed in an interface.
Self-checking unit: and sending a self-checking command to execute the bottom self-checking work to obtain a hardware self-checking result, wherein the result is used for setting the available state so as to be convenient for a user to reasonably use.
Self-calibration unit: the self calibration of the platinum resistance analog module is to measure the output value using 34980. Firstly, a calibration setting command of a certain channel is sent to a module, a setting point is sent after the channel is selected, the current set output actual value is read by using the 34980, then data are read from the 34980 and sent to the module to be stored in a memory, and the read data are simultaneously stored in a configuration file.
Temperature amount T and resistance amount R relation unit: the conversion between the two is realized according to the relation coefficient A, B, C of the conversion of the resistance quantity and the temperature quantity in the unit. The relation coefficient can be obtained directly according to the type of the thermistor, or can be converted by directly inputting the numerical value of the coefficient. The conversion relation between the two is as follows:
R＝100[1+AT+BT 2 +CT 3 (T-100)]T∈(-100,0)
R＝100[1+AT+BT 2 ]T∈[0,50]
wherein:
t-temperature, unit: the temperature is lower than the temperature;
r-platinum resistance, unit: omega;
A. b, C-platinum resistivity, each different. In this example, A is 3.9080200000E-03, B is-5.8020000000E-07, and C is-4.2735000000E-12.
The resistance value is converted into temperature:
for R.gtoreq.100, then T= [0,50]
R＝100[1+AT+BT 2 ]，T∈[0,50]
For R <100, then t= (-100, 0)
Adopting Newton iteration formula to make T 0 ＝0
n is 0,1,2, … …, and is generally calculated as T 3 And (3) obtaining the product.
For R.gtoreq.100, then T= [0,50]Or Newton's iterative formula can be used to let T 0 ＝0
Generally calculate to T 3 And (3) obtaining the product. The platinum resistor simulation load is used for replacing a real platinum resistor temperature measurement function, and high-precision resistors meeting the requirements are output to satellite thermal control equipment for measurement. The temperature measurement precision is better than +/-0.01 ℃, and the platinum resistance temperature calculation coefficient is configurable.
And a control unit: the equivalent precise resistance value is modified by controlling the resistance value of the platinum numerical control resistor, so that the temperature control and simulation of the high-precision temperature measuring loop are realized. Therefore, the platinum resistance value and the temperature value need to be converted mutually. The high-precision numerical control resistor can be controlled. In addition, the numerical control resistor adopted by the platinum resistor module has large temperature drift, the resistance value corresponding to each BIT is strong in nonlinearity, and the design requirement cannot be met according to the calibration mode and the output combination of the common resistor. For this purpose, the specific output control is transmitted to the upper computer for real-time measurement, and the feedback control is realized. The flow is shown in fig. 5: firstly, initializing a control system, establishing and monitoring SOCKET connection, circularly reading a transmitted command after connection, analyzing the command, executing corresponding operation according to the command, and returning to the result of executing the test software command.
The main instructions of the control unit include:
1) Self-checking: the hardware identification and self-checking of each module after the system is powered on mainly comprises the work of judging the type of the test equipment, judging the type of each slot test module, setting the measurement attribute of each slot, resetting the system, self-checking and the like, sending a self-checking command to execute the bottom self-checking work to obtain the result of the hardware self-checking, and giving prompt information according to the detected hardware condition to guide a user to set the test equipment according to the steps so that the equipment has a test state.
2) Platinum resistance setting: firstly, disconnecting the satellite thermal control equipment, and according to the codes set by the upper computer, measuring, feeding back and outputting by using 34980 to reach the required precise resistance value.
3) Platinum resistance self-calibration: because the temperature drift of the numerical control resistor adopted by the platinum resistor system is large, the resistance value corresponding to each BIT is strong in nonlinearity, the design requirement cannot be met according to the calibration mode and the output combination of the common resistor, and specific output control is transmitted to an upper computer for real-time measurement, and feedback control is realized. Before use, the output end of the platinum resistor simulation module is connected with four-wire parallel zero calibration cables which are made of the same material, have the same length and have the same resistance value, so that interference factors such as alternating current stray current and the like introduced in the daily use process are shielded, and the internal resistor is calibrated to a zero position. And measuring an output value by using the 34980A, firstly, transmitting a calibration setting command of a certain channel to the module, selecting the channel, transmitting a set point, reading the current set output actual value by using the 34980A, reading data from the 34980A, transmitting the data to the module, storing the data in a memory, and simultaneously storing the read data in a configuration file. The control flow is as follows: setting the state of the platinum module, returning a successful execution result by the platinum module, measuring the corresponding platinum resistance value by the 34980, and ending the self calibration. Each channel of the platinum resistance module requires 512 calibration data to be performed, and 512 cycles are performed. There are 18 channels on each card.
4) Enable output: this command controls the relay to close the connection with the satellite thermal control device, enabling the satellite thermal control device to make 4-wire value measurements.
An instruction creation unit: all commands in communication with the underlying hardware are integrated and created in the module.
A communication unit: and sending the created command to the bottom hardware, and reading the return data of the command.
And (5) returning the data analysis unit: and analyzing the read return data, combining various data information therein, and processing the data according to the information.
A data display unit: and according to the content of the current test, displaying the analyzed data so as to enable the analyzed data to be in accordance with the display format of the user interface.
A data storage unit: the data storage module stores the current setting value data in the form of an EXCEL file, forms an EXCEL file name according to the current time, and stores the EXCEL file name under a folder corresponding to the data storage module so as to facilitate the user to inquire the data.
A file importing unit: the sub-module comprises two types of file importing settings, namely, the data files in the EXCEL format which need to be set in batches can be imported into software to realize batch setting; and secondly, importing a relation coefficient of the relation between the calculated resistance value and the temperature value of each channel into software, wherein the file is also in an EXCEL format.
Test reading unit: the submodule is a module designed for matching with acceptance test and is used for reading the current output resistance value of the channel on any board card by using 34980A. Firstly, a channel on a certain board card needs to be selected, a self-calibration state setting command is sent, after the hardware receives the command, the channel belongs to a selected state, and a 34980A control function is called to read a numerical value output by the current channel and display the numerical value on an interface, so that a data reading function in acceptance test is realized.
The above examples are only preferred embodiments of the present invention, and ordinary changes and substitutions made by those skilled in the art within the scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. The numerical control platinum resistance simulation test system based on four-wire sampling is characterized by comprising a platinum resistance simulation module, a signal transfer adjustment box, a 34980 measurement module and a calibration transfer box;
the platinum resistance simulation module is connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment through the calibration transfer box, simulates a plurality of set load temperatures through controlling each path of resistance value output by the platinum resistance simulation module, and sends each path of resistance signal to the signal transfer and adjustment box;
the signal transfer and adjustment box transfers and adjusts each path of resistance signal into a signal which accords with the sampling of the 34980 measurement module;
the 34980 measurement module measures a signal output by the signal transfer conditioning box to obtain resistance information;
the calibration transfer box is used for controlling the on-off of the platinum resistance measurement acquisition circuit of the satellite thermal control equipment and the platinum resistance simulation module, and when a relay in the calibration transfer box is closed, the platinum resistance measurement acquisition circuit of the satellite thermal control equipment performs four-wire system sampling; when the relay is opened, the platinum resistance measurement acquisition circuit of the satellite thermal control equipment is disconnected with the platinum resistance simulation module.
2. The numerical control platinum resistance simulation test system based on four-wire sampling according to claim 1, wherein the platinum resistance simulation module comprises a simulation circuit of each channel and a control submodule;
each channel analog circuit comprises two digital control resistors and three resistors; the numerical control resistor Rx and the resistor R1 are connected in parallel, the numerical control resistor Ry and the resistor R2 are connected in parallel, and the two parallel branches are connected in series and then connected in series with the resistor R3 to be grounded; the output resistance of the analog circuit is:
the control submodule is used for controlling the resistance values of the numerical control resistor Rx and the numerical control resistor Ry in each channel simulation circuit, so that the resistance value output by each channel of the platinum resistor simulation module accurately simulates the set load temperature.
3. The four-wire sampling-based numerical control platinum resistance simulation test system according to claim 2, wherein the control submodule comprises a temperature amount and resistance amount conversion unit, a self-calibration unit, a configuration unit and a control unit;
the configuration unit receives the load temperature to be simulated of each channel input from the outside and sequentially forwards the load temperature to the temperature and resistance conversion unit;
the self-calibration unit calibrates the numerical control resistor in each channel analog circuit, sets one BIT for each time of the numerical control resistor, measures the BIT through a 34980 measurement module, and performs self-calibration according to the measurement result;
the temperature and resistance conversion unit converts the received temperature value into a corresponding resistance value according to the conversion relation:
R＝100[1+AT+BT 2 +CT 3 (T-100)]，T∈(-100,0)
R＝100[1+AT+BT 2 ]，T∈[0,50]
wherein T is the received temperature in degrees Celsius; r is an output resistance value, and is a unit omega; A. b, C is the resistivity;
according to the output resistor R to be obtained, the resistance values of the numerical control resistors Rx and Ry are obtained; the simulation of the set temperature is realized by setting the resistance values of the numerical control resistors Rx and Ry;
the control unit is used for inputting a temperature value to be simulated to the platinum resistance simulation module, checking the accuracy of the output resistance of the platinum resistance simulation module and controlling the on-off of the relay in the calibration transfer box.
4. A digitally controlled platinum resistance simulation test system based on four-wire sampling according to claim 3, wherein the control unit control method comprises:
transmitting the simulated temperature value to the platinum resistance simulation module, judging the simulation accuracy of the platinum resistance simulation module according to the resistance value output by the 34980 measurement module, and outputting a prohibition instruction to the calibration transfer box if the simulation is determined to be inaccurate; and if the simulation is determined to be accurate, outputting an enabling instruction to the calibration transfer box, and performing four-wire system sampling by the satellite thermal control equipment platinum resistance measurement acquisition circuit.
5. The four-wire sampling-based numerical control platinum resistor simulation test system according to claim 3, wherein the numerical control resistor Rx and the numerical control resistor Ry are respectively a numerical control resistor AD8403arz1 with a maximum resistance value of 1kΩ, and the resistors R1, R2 and R3 are respectively 20Ω, 80Ω and 24Ω; when the numerical control resistor Rx and the numerical control resistor Ry are changed, the resistance change range of the analog circuit output is 65.000 omega-120.158 omega.
6. The four-wire sampling based digitally controlled platinum resistance simulation test system of claim 1, wherein the 34980 measurement modules have 6-bit half precision, 8 34925 measurement modules are configured, the 34925 measurement modules are 40/80 channel optically isolated FET multiplexers, the supported input voltage range is ±80V, the scan channels reach 1000 channels/sec, and configured to implement single-wire, dual-wire or 4-wire modes.
7. The four-wire sampling-based numerical control platinum resistance simulation test system according to claim 4, wherein the relation between the resistance and the temperature is directly obtained by looking up a table of the resistance values of numerical control resistors Rx and Ry in the temperature and resistance conversion unit and the corresponding simulated temperature.
8. The four-wire sampling-based numerical control platinum resistance simulation test system according to claim 4, wherein the control submodule further comprises a file importing unit, the temperature values set by the channel strips are written into files, the files are imported and stored, and the configuration unit reads the temperatures of the channels and sends the temperatures to the temperature and resistance conversion unit.
9. A numerical control platinum resistance simulation test method based on four-wire sampling is characterized by comprising the following steps:
according to a plurality of load temperatures to be simulated, calculating to obtain resistance values corresponding to the load temperatures respectively;
according to each resistance value, calculating to obtain the resistance value of the numerical control resistor in the corresponding analog circuit, and setting the numerical control resistor of each channel analog circuit in the platinum resistor analog module as the calculated resistance value;
the platinum resistance simulation module is connected into a satellite thermal control equipment platinum resistance measurement acquisition circuit through a calibration adapter box, and the satellite thermal control equipment platinum resistance measurement acquisition circuit carries out four-wire system sampling on the resistance output by each channel of the platinum resistance simulation module;
carrying out transfer conditioning on the resistance value signals output by the analog circuits of all channels, measuring by using a 34980 measuring module, comparing the obtained accurate resistance value with the calculated resistance value, and if the accurate resistance value exceeds a threshold value, calibrating the relay in the transfer box to be disconnected; otherwise, the satellite thermal control equipment platinum resistance measurement acquisition circuit continues four-wire sampling.
10. The four-wire sampling-based numerical control platinum resistance simulation test method according to claim 9, wherein the platinum resistance simulation module is self-calibrated before being connected into a platinum resistance measurement acquisition circuit of the satellite thermal control equipment through a calibration transfer box, and the internal resistance of the module is calibrated to a zero position.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311284488.0A CN117433661A (en) | 2023-09-28 | 2023-09-28 | Numerical control platinum resistance simulation test system and method based on four-wire sampling |
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