Direct-current voltage temperature compensation device and method

Abstract

The invention relates to the technical field of electronic measuring instrument calibration, in particular to a direct-current voltage temperature compensation device and method, which can realize compensation of direct-current voltage measurement temperature in different ranges by controlling a multi-path signal switching module to measure an internal reference signal, reduce calibration time and achieve the effect of improving the production rate. An internal high-precision datum reference mode is adopted, the temperature coefficient of the voltage measuring circuit is obtained in real time through round-robin measurement, a variable-temperature test is not needed, and the calibration time is shortened; a period variable round-robin measurement mode is adopted, measurement of signals, reference ground and reference voltage is completed respectively, and the signal measurement rate is increased within the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic measurement instrument calibration, and particularly relates to a DC voltage temperature compensation device and method. Background Art

[0002] With the continuous progress of technology and the development of semiconductor technology and new energy technology, the requirements for electronic measurement accuracy are getting higher and higher. A high-precision digital multimeter is a multi-purpose electronic measurement instrument that usually converts functions such as AC voltage, DC current, AC current, and resistance into DC voltage for measurement. To ensure the measurement characteristics of a large range and high precision, the measurement range is usually divided into multiple ranges by means of resistors and switches. To ensure the measurement characteristics of high resolution, for digital multimeters with a higher number of digits, an integrating ADC is often used for measurement. The division of ranges and the integrating ADC usually consist of devices such as capacitors, resistors with different resistances, operational amplifiers, switches, and comparators. Different devices have different temperature coefficients. To meet the requirements of measurement accuracy within the operating temperature range, a temperature control device needs to be pre-embedded in the digital multimeter before leaving the factory, and calibration is carried out at multiple ambient temperatures to obtain the temperature coefficient. Since the equipment has high precision, after changing each temperature, it takes a long time to enter the thermal equilibrium state, thus increasing the production time and reducing the efficiency. Low-digit digital multimeters have low precision and can ignore the influence of temperature, while high-digit digital multimeters can hardly ignore the influence of ambient temperature on their measurement results. The traditional method is to change the ambient temperature of the digital multimeter and measure at multiple temperatures to obtain the temperature compensation coefficient, resulting in a significant increase in calibration time and a reduction in production speed.

[0003] It can be seen that currently, devices such as resistors, capacitors, operational amplifiers, transistors, and switches commonly used in high-precision digital multimeters convert the measured signal into DC voltage for measurement. Since different devices have different temperature coefficients, to meet the requirements of measurement accuracy within the operating temperature range, a temperature control device needs to be pre-embedded in the digital multimeter before leaving the factory, and calibration is carried out by changing the temperature to obtain the temperature coefficient. However, during calibration, the equipment has high precision and the time to reach thermal equilibrium is long, thus increasing the calibration time. Summary of the Invention

[0004] In view of this, the present invention provides a DC voltage temperature compensation device and method, which can measure the internal reference signal through a control multi-channel signal switching module to achieve temperature compensation for DC voltage measurement of different ranges, reduce the calibration time, and achieve the effect of improving the production rate.

[0005] A DC voltage temperature compensation device includes a control module, a multi-channel signal switching module, a signal conditioning module, an analog-to-digital conversion module, a voltage division module, a reference voltage source module, a constant temperature control module, and a digital signal processing module;

[0006] The control module is electrically connected to the multi-channel signal switching module, the signal conditioning module, the analog-to-digital conversion module, and the digital signal processing module respectively. Both ends of the multi-channel signal switching module are electrically connected to the signal conditioning module and the voltage dividing module respectively. One end of the signal conditioning module is connected to the analog-to-digital conversion module. The analog-to-digital conversion module is electrically connected to the reference voltage source module and the digital signal processing module. One end of the voltage dividing module is connected to the reference voltage source module. The voltage dividing module and the reference voltage source module are arranged in the constant temperature control module;

[0007] The control module controls the multi-channel signal switching module to perform signal gating periodically according to the current range and measurement speed, controls the signal conditioning module to configure the corresponding gain coefficient, controls the analog-to-digital conversion module to perform measurement and receive measurement data, and sends it to the data signal processing module.

[0008] Among them, the multi-channel signal switching module selects one of the multi-channel input signals through a control signal and connects it to the output end. The multi-channel input signals include the signal to be measured and the reference ground signal in addition to the multiple reference voltage signals output by the multiple voltage dividing modules.

[0009] Among them, the signal conditioning module is used to realize signal filtering and amplify the input signal through different resistor ratios to realize different measurement ranges.

[0010] Among them, the voltage dividing module, according to the different ranges set and the magnitude of the voltage signal output by the reference voltage source module, equally divides the voltage signal output by the reference voltage source module by adjusting the ratio of the resistor network, so as to meet the measurement requirements.

[0011] Among them, the voltage dividing module and the reference voltage source module are placed in the constant temperature control module. The constant temperature control module also includes a heat preservation medium. The constant temperature control module controls the ambient temperature of the internal devices through the heat preservation medium, heating resistor, and feedback loop.

[0012] The present invention proposes a method for compensating the temperature of a DC voltage, which is realized by using the DC voltage temperature compensation device described in the present invention, and includes the following steps:

[0013] Measure and record the values of the reference ground signal and the reference voltage signal for all ranges in an environment of room temperature 22°C or 23°C;

[0014] Through the control module, control the multi-channel signal switching module, the signal conditioning module, and the analog-to-digital conversion module to continuously and cyclically measure the signal to be measured, the reference ground signal, and the reference voltage signal, and transmit the measurement results to the digital signal processing module;

[0015] Secondly, within the digital signal processing module, a compensation coefficient is obtained by calculating the reference ground and reference voltage values recorded at an ambient temperature of 22°C or 23°C and the currently measured real-time values.

[0016] The calculated compensation coefficient and the signal measurement value are substituted into the calculation model to obtain the corrected voltage measurement value, thereby achieving temperature compensation for the DC voltage.

[0017] Among them, the reference ground signal and the reference voltage signal are measured at least once within one measurement cycle.

[0018] Among them, the specific measurement steps are as follows:

[0019] Within one measurement period, the signal, reference ground, reference voltage 1, reference voltage 2,..., reference voltage n are measured in sequence. After each signal measurement is completed, the currently saved measurement value is refreshed, and then arithmetic processing is performed.

[0020] Within one measurement period, the signal is alternately measured with the reference ground, reference voltage 1, reference voltage 2,..., reference voltage n in sequence. After each signal measurement is completed, the currently saved measurement value is refreshed, and then arithmetic processing is performed; if it is necessary to further increase the measurement speed, then during each alternate measurement process, the signal is measured at multiple consecutive points.

[0021] Beneficial effects:

[0022] 1. The device of the present invention adopts an internal high-precision reference method, and the temperature coefficient of the voltage measurement circuit is obtained in real time through cyclic measurement, without the need for variable-temperature testing, reducing the calibration time.

[0023] 2. The device of the present invention adopts a cycle-variable cyclic measurement method to separately complete the measurement of the signal, reference ground, and reference voltage, improving the signal measurement rate within the same time.

[0024] 3. The number of reference voltage signals output by the voltage division module of the device of the present invention is set according to the characteristics of the system. If the linearity is relatively high, 1 can be set, and at this time, calibration is performed by linear fitting or interpolation. When the system linearity is poor, the number of reference voltage signals output by the voltage division module needs to be increased, and the order of the calculation model is also increased accordingly, thereby improving the linearity of the system.

[0025] 4. The constant temperature control module of the device of the present invention controls the ambient temperature of the internal components through the heat preservation medium, heating resistor, and feedback loop, usually more than 10°C higher than the maximum allowable operating temperature of the device, thereby ensuring that the ambient temperature of the internal components does not change with the external temperature, reducing the influence of external ambient temperature changes on the reference voltage source module and the voltage division module.

[0026] 5. The method of the present invention is implemented based on the device of the present invention, and only needs to be calibrated at room temperature, without the need for calibration at other temperatures, thereby greatly reducing the calculation time of the temperature compensation coefficient.

[0027] 6. In the method of the present invention, the reference ground signal and the reference voltage signal are measured at least once within a measurement cycle to ensure the effect of temperature compensation. For the requirements of different measurement rates, the measurement order and the number of measurements of the signal to be measured, the reference ground signal, and the reference voltage signal within a measurement cycle can be flexibly configured. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a DC voltage temperature compensation device provided by an embodiment of the present invention.

[0029] Figure 2 It is a flowchart of a DC voltage temperature compensation method provided by an embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of a signal measurement process in a DC voltage temperature compensation method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be described in detail below with reference to the accompanying drawings and by way of examples.

[0032] This embodiment provides a DC voltage temperature compensation device, as Figure 1 shown, including: a control module, a multi-channel signal switching module, a signal conditioning module, an analog-to-digital conversion module, a voltage division module, a reference voltage source module, a constant temperature control module, and a digital signal processing module.

[0033] Among them, the control module is electrically connected to the multi-channel signal switching module, the signal conditioning module, the analog-to-digital conversion module, and the digital signal processing module respectively;

[0034] Both ends of the multi-channel signal switching module are electrically connected to the signal conditioning module and the voltage division module respectively;

[0035] One end of the signal conditioning module is connected to the analog-to-digital conversion module; one end of the analog-to-digital conversion module is electrically connected to the reference voltage source module; one end of the voltage division module is connected to the reference voltage source module;

[0036] The voltage division module and the reference voltage source module are arranged in the constant temperature control module.

[0037] In a possible implementation, the control module is used to control the multi-channel signal switching module to perform signal switching, control the signal conditioning module to configure different gain coefficients, control the analog-to-digital conversion module to perform measurement and acquisition, and transmit the control parameters and the measurement values of the analog-to-digital conversion module to the digital signal processing module for subsequent data processing. To ensure the accuracy of signal measurement, usually a period of time is delayed after signal switching for measurement. The control module in the embodiment of the present invention can be a control terminal such as an FPGA or a CPLD, and the digital signal processing module can be a processing terminal such as an MCU or a DSP.

[0038] In a possible implementation, the multi-channel signal switching module is a multiple-choice analog switch that selects one signal from multiple input signals and connects it to the signal conditioning module. The multiple input signals include a reference ground and an external signal to be measured in addition to the multiple DC voltages output by the voltage dividing module.

[0039] In a possible implementation, the signal conditioning module achieves different amplification multiples through resistors in different ratios, so as to realize the measurement of signals in multiple ranges.

[0040] In a possible implementation, the analog-to-digital conversion module is used to quantize the analog quantity output by the signal conditioning module and finally transmit the quantized digital signal to the digital signal processing module.

[0041] In a possible implementation, the voltage dividing module is used to set the voltage division ratio according to the range and the amplification multiple of the signal conditioning module for the reference voltage signal output by the reference voltage source module, so that at least one signal output by the voltage dividing module in each range can be measured. In a possible implementation, the reference voltage source module is used to output a DC voltage reference signal with low temperature coefficient and high stability for the analog-to-digital conversion module to perform analog voltage quantization.

[0042] In a possible implementation, the voltage dividing module and the reference voltage source module are placed in a constant temperature control module, and the reference voltage signal output by the reference voltage source module is voltage-divided and output to the multi-channel signal switching module according to the set ratio. In a possible implementation, the constant temperature control module further includes a heat preservation medium, and the constant temperature control module controls the ambient temperature of the internal devices in the way of the heat preservation medium, heating resistor and feedback loop, which is usually more than 10 °C higher than the maximum allowable operating temperature of the device, so as to ensure that the ambient temperature of the internal devices does not change with the external temperature and reduce the influence of the external ambient temperature change on the reference voltage source module and the voltage dividing module.

[0043] In a possible implementation, the digital signal processing module is configured to receive the configuration parameters of the control module and the digital voltage signal output by the analog-to-digital conversion module, and then perform data processing through a calculation formula to achieve the purpose of reducing the influence of ambient temperature changes on the measurement results. In addition, the digital signal processing module further includes a storage medium for storing measurement data. The storage medium is a memory such as a FLASH flash memory that does not lose data when powered off.

[0044] The specific control process of the device of the present invention is as follows: First, in a room temperature environment, usually 22°C or 23°C, according to the currently selected range, the control module respectively sends corresponding instructions to adjust the gain coefficient of the signal conditioning module, and controls the multi-channel signal switching module to connect the signal to be measured, the reference ground signal, and the reference voltage signal output by the voltage dividing module to the signal conditioning module within a measurement cycle. After the signal is stable, the analog-to-digital conversion module is controlled to perform measurement and receive the measured data. Then, the type and value of the measured signal are sent to the digital signal processing module, and the digital signal processing module stores the current value in the storage medium.

[0045] For other ranges, the same method is adopted. To ensure the measurement accuracy, the above signals can be measured multiple times, and the average value is taken to reduce the influence of noise.

[0046] When actually performing DC voltage measurement, the control process is similar to the above process. The difference is that the measured value is no longer saved at this time, but is operated with the value saved in the 22°C or 23°C room temperature environment to obtain a compensation coefficient, and then the coefficient is substituted into the calculation formula to obtain the compensated measurement voltage.

[0047] The present invention also provides a DC voltage temperature compensation method, which is implemented based on a DC voltage temperature compensation device of the present invention. By controlling the multi-channel signal switching module to measure the internal reference signal and performing real-time operation with the reference value obtained at room temperature, the temperature compensation for DC voltage measurement in different ranges is realized, and the calibration time is reduced to achieve the effect of improving the production rate. The method includes the following steps:

[0048] According to the measurement requirements, the measurement range is divided into N ranges, denoted as range 1, range 2,..., range N. In addition to signal measurement, each range also includes a reference ground and one or more reference voltage signals output by the voltage dividing module.

[0049] First, in a room temperature environment of 22°C or 23°C, after the device is fully preheated, record the reference ground signal measured in each range, denoted as Gt, and the reference voltage signals output by the voltage dividing module are denoted as Rt1, Rt2,..., Rtn.

[0050] Then, denote the signal to be measured during normal operation as S, the reference ground signal as G, and the reference voltage signals output by the voltage division module as R1, R2, …, Rn.

[0051] Gt, Rt1, Rt2, …, Rtn, as well as G, R1, R2, …, Rn are known signals. Therefore, a model can be constructed according to the number of measurement signals, usually a general polynomial, by means of fitting or interpolation. Further, calculate the coefficients of the constructed model based on the known reference ground and the reference voltage signals output by the voltage division module, and then substitute the signal S to be measured to calculate the temperature-compensated result.

[0052] In addition, the number of reference voltage signals output by the voltage division module is set according to the characteristics of the system. If the linearity is relatively high, 1 can be set. In this case, calibration is performed by means of linear fitting or interpolation. When the linearity of the system is poor, the number of reference voltage signals output by the voltage division module needs to be increased, and the order of the calculation model is also increased accordingly to improve the linearity of the system. This method only needs to be calibrated at room temperature and does not need to be calibrated at other temperatures, thus greatly reducing the calculation time of the temperature compensation coefficient.

[0053] Figure 2 The following is a flowchart of a DC voltage temperature compensation method provided by an embodiment of the present invention, which specifically includes the following steps:

[0054] S1. First, divide the device into different ranges according to the measurement requirements, and determine the amplitude of the reference voltage for each range according to the linearity characteristics of the instrument, so as to clarify the specific parameters of the voltage division module.

[0055] S2. In an environment of 22°C or 23°C at room temperature, poll and measure the reference ground and all reference voltage signals in turn and record them. To improve the operation accuracy and reduce the influence of noise, multiple measurements can be performed and the average value can be taken to achieve this.

[0056] S3. During the measurement process of the instrument, configure different measurement processes according to the requirements of the measurement speed, and then continuously measure in a loop through the control module. After each signal measurement is completed, the measurement value is transmitted from the control module to the digital signal processing module.

[0057] S4. The digital signal processing module substitutes the reference ground and reference voltage data measured in real time and the data recorded in an environment of 22°C or 23°C at room temperature into the interpolation or fitting model to calculate the coefficients. Then, according to this model and the coefficients, substitute the measured signal value to obtain the temperature-compensated measurement value.

[0058] Among them, the control module controls the multi-channel signal switching module to cyclically collect signals, the reference ground, and multiple reference voltage signals output by the voltage dividing module. Each signal is measured at least once, which is recorded as a complete cycle. According to the measurement speed requirement of the signal, the number of measurements of the signal can be appropriately increased in each complete cycle. Figure 3 It is a schematic diagram of the signal measurement process of a DC voltage temperature compensation method provided by an embodiment of the present invention. The specific measurement steps of the DC voltage temperature compensation method in this embodiment are as follows:

[0059] Within a measurement period, the signal, the reference ground, reference voltage 1, reference voltage 2,..., reference voltage n are measured in sequence. After each signal measurement is completed, the currently saved measurement value is refreshed, and then arithmetic processing is performed.

[0060] Within a measurement period, the signal is alternately measured with the reference ground, reference voltage 1, reference voltage 2,..., reference voltage n in sequence. After each signal measurement is completed, the currently saved measurement value is refreshed, and then arithmetic processing is performed. Since the number of signal measurements is increased within a period, the measurement speed of the instrument is indirectly increased. On this basis, if it is necessary to further increase the measurement speed, then during each alternating measurement process, the signal is measured at multiple consecutive points.

[0061] It should be noted that the number of the above reference voltages is related to the linearity of the system. If the linearity is better, the number of reference voltages can be appropriately reduced, and the minimum is 1.

[0062] On the other hand, from the above measurement process, it shows that within a measurement period, the reference ground and the reference voltage signal are measured at least once, and the signal can be measured multiple times. The measurement method is flexible and can be adjusted according to actual needs.

[0063] In summary, the above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A DC voltage temperature compensation device, characterized in that: It includes a control module, a multi-channel signal switching module, a signal conditioning module, an analog-to-digital conversion module, a voltage division module, a reference voltage source module, a constant temperature control module and a digital signal processing module; The control module is electrically connected to the multi-channel signal switching module, the signal conditioning module, the analog-to-digital conversion module and the digital signal processing module respectively, two ends of the multi-channel signal switching module are electrically connected to the signal conditioning module and the voltage divider module respectively, one end of the signal conditioning module is connected to the analog-to-digital conversion module, the analog-to-digital conversion module is electrically connected to the reference voltage source module and the digital signal processing module, one end of the voltage divider module is connected to the reference voltage source module, and the voltage divider module and the reference voltage source module are arranged in the constant temperature control module; The control module controls the multi-channel signal switching module to periodically select signals according to the current range and measurement speed, controls the signal conditioning module to configure the corresponding gain coefficient, controls the analog-to-digital conversion module to measure and receive measurement data, and sends it to the data signal processing module.

2. The device according to claim 1, characterized in that The multi-channel signal switching module selects one of the multi-channel input signals through a control signal and connects it to the output end. In addition to the multiple reference voltage signals output by the multiple voltage divider modules, the multi-channel input signals also include a signal to be tested and a reference ground signal.

3. The device according to claim 2, characterized in that ,The signal conditioning module is used to implement signal filtering and amplify the input signal through different ,resistance ratios to achieve different measurement ranges.

4. The device according to any one of claims 1 to 3, characterized in that The voltage divider module divides the voltage signal output by the reference voltage source module in equal proportions by adjusting the ratio of the resistor network according to the different ranges set and the size of the voltage signal output by the reference voltage source module, thereby meeting the measurement requirements.

5. The device according to claim 1, characterized in that The voltage divider module and the reference voltage source module are placed in the constant temperature control module, which also includes a heat preservation medium. The constant temperature control module controls the ambient temperature of the internal device by means of the heat preservation medium, the heating resistor and the feedback loop.

6. A DC voltage temperature compensation method, characterized in that: The DC voltage temperature compensation device according to any one of claims 1 to 5 is used to implement the method, comprising the following steps: At room temperature of 22°C or 23°C, measure the reference ground signal and reference voltage signal of all ranges and record the values; The control module controls the multi-channel signal switching module, the signal conditioning module, and the analog-to-digital conversion module to continuously cycle through the measured signal, the reference ground signal, and the reference voltage signal for measurement, and transmits the measurement results to the digital signal processing module; Secondly, in the digital signal processing module, the compensation coefficient is obtained by calculating the reference ground and reference voltage values ​​recorded under the room temperature of 22° C. or 23° C. and the current real-time measured value; The calculated compensation coefficient and the signal measurement value are brought into the calculation model to obtain the corrected voltage measurement value, thereby realizing the temperature compensation of the DC voltage.

7. The method according to claim 6, characterized in that The reference ground signal and the reference voltage signal are measured at least once in one measurement cycle.

8. The method according to claim 6 or 7, characterized in that The specific steps of the measurement are as follows: In one measurement cycle, the signal, reference ground, reference voltage 1, reference voltage 2, ..., reference voltage n are measured in sequence. After each signal measurement is completed, the currently saved measurement value is refreshed and then the calculation is performed. ; In one measurement cycle, the signal and the reference ground, reference voltage 1, reference voltage 2, ..., reference voltage n are measured alternately in sequence. After each measurement of a signal is completed, the currently saved measurement value is refreshed and then the calculation process is performed; If the measurement speed needs to be further increased, multiple points of the signal are measured continuously during each alternating measurement process.

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