CN112630516A - High-precision sensor current signal sampling method and circuit - Google Patents
High-precision sensor current signal sampling method and circuit Download PDFInfo
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- CN112630516A CN112630516A CN202011392525.6A CN202011392525A CN112630516A CN 112630516 A CN112630516 A CN 112630516A CN 202011392525 A CN202011392525 A CN 202011392525A CN 112630516 A CN112630516 A CN 112630516A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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Abstract
The invention relates to a high-precision sensor current signal sampling method and a high-precision sensor current signal sampling circuit. The method of the invention comprises the following steps: 1) sampling is carried out at the output end of the sensor loop, and loop current is converted into a voltage signal; 2) filtering the acquired voltage signal to filter channel noise; 3) amplifying the filtered voltage signal and outputting the amplified voltage signal; 4) and performing analog-to-digital conversion on the received voltage signal and outputting a digital signal. The invention converts tiny current variables in the sensor loop into voltage signals which can be monitored, and simultaneously converts the voltage signals into digital signals to be output with high reliability, and has the advantages of high acquisition precision, low noise and capability of carrying out overvoltage protection on the port of the operational amplifier circuit.
Description
Technical Field
The invention relates to the fields of aviation, navigation, industrial control and the like, in particular to a method and a circuit for sampling a current signal of a high-precision sensor.
Background
The loop current output is widely applied to the fields of sensors and the like, the loop current value is used as the output variable of the sensor, for a high-precision sensor circuit, the system error is usually within 0.1% or 0.01%, the uA-level current change in the loop needs to be monitored, the traditional current sampling method is completed by an external instrument, the sampling precision is low, channel noise exists, the error of the collected current value is large, the precision is far lower than the self precision of the sensor, and the high-precision requirement of the sensor system cannot be met.
Disclosure of Invention
The invention provides a high-precision sensor current signal sampling method and circuit for solving the technical problems in the background art, which convert tiny current variables in a sensor loop into voltage signals capable of being monitored, and simultaneously convert the voltage signals into digital signals for output with high reliability.
The technical solution of the invention is as follows: the invention relates to a high-precision sensor current signal sampling method, which is characterized in that: the method comprises the following steps:
1) sampling is carried out at the output end of the sensor loop, and loop current is converted into a voltage signal;
2) filtering the acquired voltage signal to filter channel noise;
3) amplifying the filtered voltage signal and outputting the amplified voltage signal;
4) and performing analog-to-digital conversion on the received voltage signal and outputting a digital signal.
Preferably, in step 3), the filtered voltage signal is amplified according to a required amplification factor and then output.
A circuit for realizing the high-precision sensor current signal sampling method is characterized in that: the circuit comprises a sampling resistor, a filter circuit, an operational amplifier circuit and a digital-to-analog conversion chip, wherein the sampling resistor is connected with the digital-to-analog conversion chip through the filter circuit, the operational amplifier circuit and the digital-to-analog conversion chip in sequence.
Preferably, the filter circuit includes a resistor R1, a resistor R2 and a capacitor C1, the operational amplifier circuit includes an operational amplifier a1, an operational amplifier a2 and an operational amplifier A3, one end of the sampling resistor is connected to the positive input terminal of the operational amplifier a1 through a resistor R1, the other end of the sampling resistor is connected to the positive input terminal of the operational amplifier a2 through a resistor R2, the sampling resistor is connected in parallel with the capacitor C1, the output terminal of the operational amplifier a1 is connected to the negative input terminal of the operational amplifier A3, the output terminal of the operational amplifier a2 is respectively connected to the positive input terminal of the operational amplifier A3 and the ground, and the output terminal of the operational amplifier A3 is connected to the digital.
Preferably, the operational amplifier circuit further includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, the resistor R7 is connected between the negative input terminal and the output terminal of the operational amplifier a1, the resistor R8 is connected between the negative input terminal and the output terminal of the operational amplifier a2, the resistor R3 is connected between the output terminal of the operational amplifier a1 and the negative input terminal of the operational amplifier A3, the resistor R4 is connected between the output terminal of the operational amplifier a2 and the positive input terminal of the operational amplifier A3, the output terminal of the operational amplifier a2 is grounded through the resistor R6, and the resistor R5 is connected between the negative input terminal and the output terminal of the operational amplifier A3.
Preferably, the circuit further comprises a resistor R9, and a resistor R9 is connected between the negative input terminal of the operational amplifier a1 and the negative input terminal of the operational amplifier a 2.
Preferably, the circuit further comprises two fets, one of which is connected between the resistor R1 and the positive input of the operational amplifier a1, and the other of which is connected between the resistor R2 and the positive input of the operational amplifier a 2.
Preferably, the sampling resistance is 0.1% precision resistance.
The invention provides a method and a circuit for sampling a high-precision sensor current signal, which are used for acquiring a tiny current variable output by a sensor. Therefore, the invention has the advantages of high acquisition precision, low noise and capability of carrying out overvoltage protection on the port of the operational amplifier circuit.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The invention provides a high-precision sensor current signal sampling method, which comprises the following steps:
1) sampling is carried out at the output end of the sensor loop, and loop current is converted into a voltage signal;
2) filtering the acquired voltage signal to filter channel noise;
3) amplifying the filtered voltage signal according to a required amplification factor and then outputting the amplified voltage signal;
4) and D/A conversion is carried out on the received voltage signal, and the digital signal is output.
The technical solution of the present invention is further described in detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1, the structure of the embodiment of the present invention includes a sampling resistor, a filter circuit, an operational amplifier circuit, and a digital-to-analog conversion chip, where the sampling resistor is connected to the input end of the sensor loop to convert the loop current into a voltage signal, and the sampling resistor uses a 0.1% precision resistor; the filter circuit is arranged between the sampling resistor and the input end of the operational amplifier circuit, and the voltage signal acquired by the sampling resistor is filtered by the filter circuit to remove channel noise; the input end of the operational amplifier circuit is connected with the output end of the filter circuit, receives the filtered voltage signal, amplifies the filtered voltage signal according to the amplification factor and outputs the amplified voltage signal, the digital-to-analog conversion chip is connected with the output end of the operational amplifier circuit and used for performing analog-to-digital conversion on the received voltage signal and outputting a digital signal, and the digital-to-analog conversion chip adopts the existing digital-to-analog conversion chip.
The filter circuit comprises a resistor R1, a resistor R2 and a capacitor C1, the operational amplifier circuit comprises an operational amplifier A1, an operational amplifier A2, an operational amplifier A3, a resistor R3, a resistor R4, a resistor R5, a resistor R6 and a resistor R6, one end of a sampling resistor is connected to the positive input end of the operational amplifier A6 through the resistor R6, the other end of the sampling resistor is connected to the positive input end of the operational amplifier A6 through the resistor R6, the sampling resistor is connected in parallel with the capacitor C6, the output end of the operational amplifier A6 is connected to the negative input end of the operational amplifier A6 through the resistor R6, the output end of the operational amplifier A6 is connected to the positive input end of the operational amplifier A6 through the resistor R6, the resistor R6 is connected to the ground through the resistor R6, the resistor R6 is connected between the negative input end and the output end of the operational amplifier A6, the negative input end of the operational amplifier A6 is indirectly connected, the output end of the operational amplifier A3 is connected with a digital-to-analog conversion chip. The three operational amplifiers A1, A2 and A3 form a two-stage operational amplifier circuit, which is used for amplifying the sampled voltage signal in a specific proportion; the resistors R3, R4, R5, R6, R7 and R8 are used for configuring output parameters of the operational amplifiers of all levels, and the resistance values are fixed;
the circuit further comprises a resistor R9, the resistor R9 is connected between the negative input end of the operational amplifier A1 and the negative input end of the operational amplifier A2, the resistor R9 is used for configuring the gain of the whole operational circuit, and the resistance value is selected according to specific application scenes.
The voltage dividing resistors R3, R4, R5, R6, R7, R8 and R9 form a gain adjusting circuit, and the voltage amplification factor is controlled by changing the configuration resistance value.
The circuit of the present invention further includes two fets, one fet being connected between the resistor R1 and the positive input of the operational amplifier a1, and the other fet being connected between the resistor R2 and the positive input of the operational amplifier a 2. The field effect transistor protects the operational amplifier at the input terminal to prevent the input voltage from being too large.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A high-precision sensor current signal sampling method is characterized in that: the method comprises the following steps:
1) sampling is carried out at the output end of the sensor loop, and loop current is converted into a voltage signal;
2) filtering the acquired voltage signal to filter channel noise;
3) amplifying the filtered voltage signal and outputting the amplified voltage signal;
4) and performing analog-to-digital conversion on the received voltage signal and outputting a digital signal.
2. The method of sampling a high accuracy sensor current signal of claim 1, further comprising: in the step 3), the filtered voltage signal is amplified according to the required amplification factor and then output.
3. A circuit for implementing the high accuracy sensor current signal sampling method of claim 1, wherein: the circuit comprises a sampling resistor, a filter circuit, an operational amplifier circuit and a digital-to-analog conversion chip, wherein the sampling resistor is connected with the digital-to-analog conversion chip through the filter circuit, the operational amplifier circuit and the digital-to-analog conversion chip in sequence.
4. The high accuracy sensor current signal sampling circuit of claim 3, wherein: the filter circuit comprises a resistor R1, a resistor R2 and a capacitor C1, the operational amplifier circuit comprises an operational amplifier A1, an operational amplifier A2 and an operational amplifier A3, one end of a sampling resistor is connected with the positive input end of the operational amplifier A1 through a resistor R1, the other end of the sampling resistor is connected with the positive input end of an operational amplifier A2 through a resistor R2, the sampling resistor is connected with the capacitor C1 in parallel, the output end of the operational amplifier A1 is connected with the negative input end of the operational amplifier A3, the output end of the operational amplifier A2 is respectively connected with the positive input end of the operational amplifier A3 and the ground, and the output end of the operational amplifier A3 is connected with the digital-to-analog conversion chip.
5. The high accuracy sensor current signal sampling circuit of claim 4, wherein: the operational amplifier circuit further comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, the resistor R7 is connected between the negative input end and the output end of the operational amplifier A1, the resistor R8 is connected between the negative input end and the output end of the operational amplifier A2, the resistor R3 is connected between the output end of the operational amplifier A1 and the negative input end of the operational amplifier A3, the resistor R4 is connected between the output end of the operational amplifier A2 and the positive input end of the operational amplifier A3, the output end of the operational amplifier A2 is grounded through the resistor R6, and the resistor R5 is connected between the negative input end and the output end of the operational amplifier A3.
6. The high accuracy sensor current signal sampling circuit of claim 5, wherein: the circuit also includes a resistor R9, and a resistor R9 is connected between the negative input terminal of the operational amplifier A1 and the negative input terminal of the operational amplifier A2.
7. The high accuracy sensor current signal sampling circuit of any of claims 3 to 6, wherein: the circuit also includes two fets, one of which is connected between the resistor R1 and the positive input of the operational amplifier a1, and the other of which is connected between the resistor R2 and the positive input of the operational amplifier a 2.
8. The high accuracy sensor current signal sampling circuit of claim 7, wherein: the sampling resistance is 0.1% precision resistance.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011392525.6A CN112630516A (en) | 2020-12-05 | 2020-12-05 | High-precision sensor current signal sampling method and circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011392525.6A CN112630516A (en) | 2020-12-05 | 2020-12-05 | High-precision sensor current signal sampling method and circuit |
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| CN112630516A true CN112630516A (en) | 2021-04-09 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
| CN113691275A (en) * | 2021-09-09 | 2021-11-23 | 苏州汇川控制技术有限公司 | Digital signal transmission circuit and digital signal transmission device |
| CN113899941A (en) * | 2021-09-27 | 2022-01-07 | 湖北航天技术研究院总体设计所 | Current acquisition circuit and acquisition method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109239432A (en) * | 2018-07-26 | 2019-01-18 | 华中科技大学 | A kind of weak current circuit of nitrogen oxide sensor |
| CN210142143U (en) * | 2019-03-22 | 2020-03-13 | 南京鑫华莹自动化设备有限公司 | High-precision current sampling circuit |
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2020
- 2020-12-05 CN CN202011392525.6A patent/CN112630516A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109239432A (en) * | 2018-07-26 | 2019-01-18 | 华中科技大学 | A kind of weak current circuit of nitrogen oxide sensor |
| CN210142143U (en) * | 2019-03-22 | 2020-03-13 | 南京鑫华莹自动化设备有限公司 | High-precision current sampling circuit |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
| CN113691275A (en) * | 2021-09-09 | 2021-11-23 | 苏州汇川控制技术有限公司 | Digital signal transmission circuit and digital signal transmission device |
| CN113899941A (en) * | 2021-09-27 | 2022-01-07 | 湖北航天技术研究院总体设计所 | Current acquisition circuit and acquisition method |
| CN113899941B (en) * | 2021-09-27 | 2023-08-18 | 湖北航天技术研究院总体设计所 | Current acquisition circuit and acquisition method |
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