阅读说明：本技术 利用电阻热噪声电压测量电阻元件温度的系统及方法 (System and method for measuring temperature of resistance element by using resistance thermal noise voltage ) 是由 陈震 陈子杰 赵晓冬 于 2021-07-13 设计创作，主要内容包括：本发明涉及一种利用电阻热噪声电压测量电阻元件温度的系统及方法,包括：测温电阻,为待测样品；热噪声电压提取系统,用于采集并放大总噪声电压；热噪声电压提取系统包括前置放大器和带通滤波器,前置放大器与测温电阻双通道差分连接,带通滤波器用于设置测量的总噪声电压的带宽和增益；温度输出系统,包括电压采集卡和计算机,前置放大器输出端与电压采集卡输入端串联,电压采集卡输出端与计算机串联；电压采集卡用于采集热噪声电压提取系统输出的总噪声电压并输出至计算机,由计算机处理得到测温电阻的热噪声电压信号,并计算得到测温电阻的温度后输出。本发明利用电阻本身的热噪声电压,不需要标定,并能够在极端的条件下测试温度。(The invention relates to a system and a method for measuring the temperature of a resistance element by using resistance thermal noise voltage, comprising the following steps: the temperature measuring resistor is a sample to be measured; the thermal noise voltage extraction system is used for collecting and amplifying the total noise voltage; the thermal noise voltage extraction system comprises a preamplifier and a band-pass filter, wherein the preamplifier is in double-channel differential connection with the temperature measuring resistor, and the band-pass filter is used for setting the bandwidth and the gain of the measured total noise voltage; the temperature output system comprises a voltage acquisition card and a computer, wherein the output end of the preamplifier is connected with the input end of the voltage acquisition card in series, and the output end of the voltage acquisition card is connected with the computer in series; the voltage acquisition card is used for acquiring the total noise voltage output by the thermal noise voltage extraction system and outputting the total noise voltage to the computer, the thermal noise voltage signal of the temperature measuring resistor is obtained by processing the total noise voltage signal by the computer, and the temperature of the temperature measuring resistor is output after the temperature of the temperature measuring resistor is obtained by calculation. The invention utilizes the thermal noise voltage of the resistor, does not need calibration and can test the temperature under extreme conditions.)

1. A system for measuring the temperature of a resistive element using resistive thermal noise voltage, comprising:

the temperature measuring resistor is a sample to be measured;

the thermal noise voltage extraction system is used for collecting and amplifying the total noise voltage; the thermal noise voltage extraction system comprises a preamplifier and a band-pass filter, wherein the preamplifier is in double-channel differential connection with the temperature measuring resistor, and the band-pass filter is used for setting the bandwidth and the gain of the measured total noise voltage;

the temperature output system comprises a voltage acquisition card and a computer, wherein the output end of the preamplifier is connected with the input end of the voltage acquisition card in series, and the output end of the voltage acquisition card is connected with the computer in series; the voltage acquisition card is used for acquiring the total noise voltage output by the thermal noise voltage extraction system and outputting the total noise voltage to the computer, the thermal noise voltage signal of the temperature measuring resistor is obtained by processing the total noise voltage signal by the computer, and the temperature of the temperature measuring resistor is output after the temperature of the temperature measuring resistor is obtained by calculation.

2. The system for measuring the temperature of a resistive element using resistive thermal noise voltage according to claim 1, wherein the resistance value of the temperature measuring resistor is 10k Ω to 80k Ω.

3. A method for measuring the temperature of a resistive element using the system of claim 1, wherein the optimal test bandwidth of the thermal noise voltage extraction system and the sampling time of the voltage acquisition card are selected according to the temperature measurement error of the thermal noise voltage required by the user and the limit of the adjustable parameter of the device, and the sampling rate of the voltage acquisition card is set to be more than twice of the highest frequency of the test signal;

the thermal noise voltage extraction system is set to be in a low noise amplification mode, so that the thermal noise voltage extraction system can rapidly amplify the thermal noise voltage to a measurable level; then, setting the gain of the thermal noise voltage extraction system according to the resolution of the temperature output system, and ensuring that the temperature output system can obtain a tiny thermal noise voltage signal and further convert the tiny thermal noise voltage signal into temperature output;

the method for processing the total noise voltage to obtain the thermal noise voltage signal of the temperature measuring resistor and outputting the temperature of the temperature measuring resistor comprises the following steps:

total noise voltage V measured by temperature output system_{Total noise}Consists of three parts, including:

voltage noise V of preamplifier_{Voltage noise}Current noise V of preamplifier_{Current noise}And the thermal noise voltage V 'of the temperature measuring resistor'_{Thermal noise}The expression is as follows:

in the above formula, V_{Voltage noise}Can be measured by short-circuiting the input end of the preamplifier;I_noise(s)Is a noise current;

considering that the temperature measuring resistor and the preamplifier have an input capacitor, the calculation formula of the thermal noise voltage theoretical value of the input capacitor is as follows:

in the above formula, f is the noise frequency, f_hUpper limit of noise frequency, f_lIs the lower limit of noise frequency, R is the resistance of temperature measuring resistor, T is the temperature of temperature measuring resistor, C is input capacitor, gain is noise voltage gain, k_BBoltzmann constant;

the theoretical value of the thermal noise voltage and the total noise voltage V obtained by measurement are compared_{Total noise}Fitting, wherein in the fitting process, the temperature T of the temperature measuring resistor is measured by attaching the temperature measuring resistor to the thermocouple, the input capacitor C is further obtained through calculation, and I is calculated according to the calculation formula of the thermal noise voltage theoretical value of the input capacitor while the capacitor C is obtained through fitting_Noise(s)And then the current noise V is obtained_{Current noise}Total noise voltage V_{Total noise}Subtracting voltage noise V_{Voltage noise}Sum current noise V_{Current noise}The thermal noise voltage of the test resistor tested by the experiment can be obtained, and then the temperature of the corresponding temperature measuring resistor is calculated according to the calculation formula of the theoretical value of the thermal noise voltage and is output.

Technical Field

The invention relates to the technical field of temperature measurement, in particular to a system and a method for measuring the temperature of a resistance element by using resistance thermal noise voltage.

Background

In the prior art, the temperature is mainly measured by a thermocouple measuring method, a resistance measuring method and a diode measuring method. In any temperature measurement method, temperature calibration is required, and a thermocouple test method is taken as an example: after the thermocouple is manufactured, basic calibration is required, i.e., the thermocouple is designed by a specific circuit signal to obtain a more accurate compensation temperature, such as zero degrees centigrade, and on this basis, the accurate temperature is obtained by comparing the temperature with the temperature difference of the target sample. Because the compensated temperature after calibration drifts with time, the thermocouple is used for measuring temperature under some high-temperature and severe conditions, even more frequent calibration is needed, a large amount of time is consumed, and accurate temperature cannot be obtained quickly. In addition, the conventional temperature measurement method has a large limitation in the measurement range because the temperature-resistance relationship of metal fails at very low/high temperatures (40K or less or 1000K or more).

According to the energy dissipation theory, under the influence of temperature, free electrons in the resistor generate thermal disturbance to generate an electric signal, called a thermal noise voltage signal, at two ends of the resistor. Usually, the thermal noise voltage signal belongs to an interference signal in a circuit and needs to be specially eliminated. However, the thermal noise voltage signal has a very important physical significance, which corresponds one-to-one to the absolute temperature of the resistor. Therefore, the required temperature can be obtained by analyzing the thermal noise voltage signal at two ends of the resistor. According to the Nyquist noise theorem, the temperature tested by the method is absolute temperature, no temperature calibration is needed, and the range of the tested temperature is not limited. The invention is a reliable test method designed based on the theory.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a system and a method for measuring the temperature of a resistance element by using resistance thermal noise voltage, which solve the problem that the conventional temperature measurement method needs to calibrate the temperature in advance and make up the defect that the conventional temperature measurement method fails under extreme conditions.

The technical scheme adopted by the invention is as follows:

a system for measuring the temperature of a resistive element using resistive thermal noise voltage, comprising:

the temperature measuring resistor is a sample to be measured;

the thermal noise voltage extraction system is used for collecting and amplifying the total noise voltage; the thermal noise voltage extraction system comprises a preamplifier and a band-pass filter, wherein the preamplifier is in double-channel differential connection with the temperature measuring resistor, and the band-pass filter is used for setting the bandwidth and the gain of the measured total noise voltage;

the temperature output system comprises a voltage acquisition card and a computer, wherein the output end of the preamplifier is connected with the input end of the voltage acquisition card in series, and the output end of the voltage acquisition card is connected with the computer in series; the voltage acquisition card is used for acquiring the total noise voltage output by the thermal noise voltage extraction system and outputting the total noise voltage to the computer, the thermal noise voltage signal of the temperature measuring resistor is obtained by processing the total noise voltage signal by the computer, and the temperature of the temperature measuring resistor is output after the temperature of the temperature measuring resistor is obtained by calculation.

The resistance value of the temperature measuring resistor is 10k omega to 80k omega.

According to temperature measurement error of thermal noise voltage required by a user and the limit of adjustable parameters of equipment, the optimal test bandwidth of a thermal noise voltage extraction system and the sampling time of a voltage acquisition card are selected, and the sampling rate of the voltage acquisition card is set to be more than twice of the highest frequency of a test signal;

the thermal noise voltage extraction system is set to be in a low noise amplification mode, so that the thermal noise voltage extraction system can rapidly amplify the thermal noise voltage to a measurable level; then, setting the gain of the thermal noise voltage extraction system according to the resolution of the temperature output system, and ensuring that the temperature output system can obtain a tiny thermal noise voltage signal and further convert the tiny thermal noise voltage signal into temperature output;

the method for processing the total noise voltage to obtain the thermal noise voltage signal of the temperature measuring resistor and outputting the temperature of the temperature measuring resistor comprises the following steps:

total noise voltage V measured by temperature output system_{Total noise}Consists of three parts, including:

voltage noise V of preamplifier_{Voltage noise}Current noise V of preamplifier_{Current noise}And the thermal noise voltage V 'of the temperature measuring resistor'_{Thermal noise}Expression ofThe formula is as follows:

in the above formula, V_{Voltage noise}Can be measured by short-circuiting the input end of the preamplifier;

I_noise(s)Is a noise current;

considering that the temperature measuring resistor and the preamplifier have an input capacitor, the calculation formula of the thermal noise voltage theoretical value of the input capacitor is as follows:

in the above formula, f is the noise frequency, f_hUpper limit of noise frequency, f_lIs the lower limit of noise frequency, R is the resistance of temperature measuring resistor, T is the temperature of temperature measuring resistor, C is input capacitor, gain is noise voltage gain, k_BBoltzmann constant;

the theoretical value of the thermal noise voltage and the total noise voltage V obtained by measurement are compared_{Total noise}Fitting, wherein in the fitting process, the temperature T of the temperature measuring resistor is measured by attaching the temperature measuring resistor to the thermocouple, the input capacitor C is further obtained through calculation, and I is calculated according to the calculation formula of the thermal noise voltage theoretical value of the input capacitor while the capacitor C is obtained through fitting_Noise(s)Further, the current noise V is calculated_{Current noise}Total noise voltage V_{Total noise}Subtracting voltage noise V_{Voltage noise}Sum current noise V_{Current noise}The thermal noise voltage of the test resistor tested by the experiment can be obtained, and then the temperature of the corresponding temperature measuring resistor is calculated according to the calculation formula of the theoretical value of the thermal noise voltage and is output.

The invention has the following beneficial effects:

the temperature of the sample to be tested is obtained by utilizing the resistance thermal noise voltage, compared with the existing temperature measurement method, the temperature measurement method does not need to carry out any calibration and calibration, compared with the traditional temperature measurement method, the temperature measurement method not only can quickly obtain the temperature of the sample to be tested, but also has no limitation of the temperature measurement range, and can achieve the same test precision. The material of the test sample of the present invention is not limited, and there is no measurement interval limitation within the range where the property of the material is not changed.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

FIG. 2 is a comparison graph of the thermal noise voltage test results of the metal film resistor samples with different resistance values by using the method of the present invention.

FIG. 3 is a comparison of the test temperatures obtained using the method of the present invention and the test temperature of a type K thermocouple.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

A system for measuring a temperature of a resistive element using a resistive thermal noise voltage according to the present embodiment, as shown in fig. 1, includes:

the temperature measuring resistor is a sample to be measured;

the thermal noise voltage extraction system is used for collecting and amplifying the total noise voltage; the thermal noise voltage extraction system comprises a preamplifier and a band-pass filter, wherein the preamplifier is in double-channel differential connection with the temperature measuring resistor and is connected with the band-pass filter in series, and the band-pass filter is used for setting the bandwidth and the gain of the measured total noise voltage;

the temperature output system comprises a voltage acquisition card and a computer, wherein the output end of the preamplifier is connected with the input end of the voltage acquisition card in series, and the output end of the voltage acquisition card is connected with the computer in series; the voltage acquisition card is used for acquiring the total noise voltage output by the thermal noise voltage extraction system and outputting the total noise voltage to the computer, the thermal noise voltage signal of the temperature measuring resistor is obtained by processing the total noise voltage signal by the computer, and the temperature of the temperature measuring resistor is output after the temperature of the temperature measuring resistor is obtained by calculation.

The resistance value of the temperature measuring resistor is 10k omega to 80k omega.

The temperature output system can set the point number of collecting noise voltage per second, namely the voltage sampling rate, and the time of collecting voltage signals, namely the sampling time, so as to adjust the precision of temperature output.

The shape and size of the temperature measuring resistor used as a sample to be measured are not limited, two pins are usually required to be designed to facilitate the lead wire of the temperature measuring resistor to be connected to a preamplifier, and the material can be a carbon film resistor or a metal film resistor.

In order to test accuracy, the resistance value of the temperature measuring resistor is preferably selected to be 10k omega to 80k omega, the resistance value of the temperature measuring resistor is too small and can be covered by voltage noise of the thermal noise voltage extraction system (the resistance value is too small, the voltage noise is far greater than the thermal noise voltage and is not beneficial to extraction), the resistance value is too large and is influenced by self current noise of the thermal noise voltage extraction system (the resistance value is too large, the current noise is far greater than the thermal noise voltage and is also not beneficial to extraction), and the test accuracy can be reduced.

Therefore, if the resistance value of the sample to be tested is between 10k Ω and 80k Ω, the sample can be directly used as a temperature measuring resistor to measure the thermal noise voltage signal, if the resistance of the sample to be tested does not meet the above conditions, such as some conductive materials or insulating materials, the temperature sample to be tested needs to be electrically insulated and jointed with the designed resistor (the resistance value is between 10k Ω and 80k Ω) meeting the test requirements, and then the temperature signal is measured, so that the temperature measuring resistor and the sample to be tested need to be well thermally transmitted while being electrically insulated, the temperature of the temperature measuring resistor and the sample to be tested is ensured to be consistent, and the temperature measuring resistor and the sample to be tested are usually jointed by using thermal conductive glue (thermal paste). By this design, the temperature of any sample can be tested.

The "computer" in FIG. 1 is the "computer" described above.

A method for measuring the temperature of the resistance element by using the system of the embodiment comprises the following steps:

selecting the optimal test bandwidth of a thermal noise voltage extraction system and the sampling time of a voltage acquisition card according to the temperature measurement error of the thermal noise voltage required by a user and the limit of adjustable parameters of equipment, wherein the sampling rate of the voltage acquisition card is set to be more than twice of the highest frequency of a test signal;

the thermal noise voltage extraction system is set to be in a low noise amplification mode, so that the thermal noise voltage extraction system can rapidly amplify the thermal noise voltage to a measurable level; then, setting the gain of the thermal noise voltage extraction system according to the resolution of the temperature output system, and ensuring that the temperature output system can obtain a tiny thermal noise voltage signal and further convert the tiny thermal noise voltage signal into temperature output;

the bandwidth may be determined by setting the cut-off frequency of the low and high pass of the band pass filter.

The above temperature measurement error can be estimated by RICE inequality as follows:

in the formula (1), Δ T is an error of the test temperature, T is a temperature of the test resistor, T is a sampling time, and Δ f is a test bandwidth.

The method for processing the total noise voltage to obtain the thermal noise voltage signal of the temperature measuring resistor and outputting the temperature of the temperature measuring resistor comprises the following steps:

the purpose of testing the thermal noise voltage in this embodiment is to extract the temperature of the temperature measuring resistor, so the accuracy of the thermal noise voltage actually determines the accuracy of the temperature, and the measurement result should be compared with the theoretical value of the thermal noise voltage.

The theoretical value of the original thermal noise voltage without considering the input capacitance is calculated as follows:

where f is the noise frequency, f_hUpper limit of noise frequency, f_lIs the lower limit of noise frequency, R is the resistance of the temperature measuring resistor, T is the temperature of the temperature measuring resistor, gain is the noise voltage gain, k_BBoltzmann constant;

however, because the temperature measuring resistor and the preamplifier have an input capacitor, and the relation between the thermal noise voltage and the input capacitor is shown in the formula (3), the theoretical value of the thermal noise voltage considering the actual test of the input capacitor is calculated by the formula (3), and the formula (3) shows that the temperature at two ends of the equation is only unknown, so that the temperature of the experimental test sample can be obtained by using the tested thermal noise voltage value.

Where f is the noise frequency, f_hUpper limit of noise frequency, f_lIs the lower limit of noise frequency, R is the resistance of the temperature measuring resistor, T is the temperature of the temperature measuring resistor, gain is the noise voltage gain, k_BBoltzmann constant; c is an input capacitor;

after the theoretical value of the thermal noise voltage is obtained, the total noise voltage V is obtained according to experimental tests_{Total noise}Composed of three parts, including thermal noise voltage V 'of temperature measuring resistor'_{Thermal noise}Voltage noise V of preamplifier_{Voltage noise}And the current noise V of the preamplifier_{Current noise}The expression is as follows:

wherein, V_{Voltage noise}Can be measured by short-circuiting the input end of the preamplifier;I_noise(s)Is a noise current.

The theoretical value of the thermal noise voltage and the total noise voltage V obtained by measurement are compared_{Total noise}Fitting is carried out, in the fitting process, the temperature T of the temperature measuring resistor is measured by attaching the temperature measuring resistor to the thermocouple, then the input capacitor C is obtained through calculation, and I is fitted according to the formula (4) while the capacitor C is obtained through fitting_Noise(s)According to I_Noise(s)Calculating the current noise V_{Current noise}Total noise voltage V_{Total noise}Subtracting voltage noise V_{Voltage noise}And electricityFlow noise V_{Current noise}The thermal noise voltage of the test resistor tested by the experiment can be obtained, and then the temperature of the corresponding temperature measuring resistor is obtained and output according to the formula (3).

In the process of solving the input capacitance and the current noise by fitting, the temperature T is the testing temperature of the thermocouple-attached temperature measuring resistor, the theoretical value of the thermal noise voltage (the temperature of the temperature measuring resistor reflected by the temperature measurement of the thermocouple) calculated after the input capacitance is considered is compared with the noise voltage value (the temperature of the temperature measuring resistor reflected by the thermal noise voltage) obtained by actual testing, and whether the theoretical value and the noise voltage value are self-consistent is observed, so that the accuracy of testing the temperature by utilizing the thermal noise voltage is reflected.

The fitting calculation, the comparison process of the thermal noise voltage theory and the experimental value are processed by a computer.

As shown in fig. 2, the results of thermal noise voltage tests on the metal film resistor samples with different resistance values are compared in the temperature measurement method of this embodiment. The slope difference is the error between the test temperature and the actual temperature, and the temperature error is 3% as can be seen from the figure.

As shown in fig. 3, in order to compare the results of the temperature measurement using the thermal noise voltage and the temperature measurement using the K-type thermocouple obtained by the temperature measurement method of the present embodiment, the results of the temperature measurement using the thermal noise voltage and the temperature measurement using the K-type thermocouple are plotted in the same graph, and it is found that the results of the temperature measurement using the thermal noise and the results of the temperature measurement using the thermocouple are very close to each other, the linear fitting coefficient of the two is 0.998, and the error of the results of the two is ± 1K, which proves the stability of the temperature measurement using the thermal noise.