Field grinding electric field sensor signal conditioning method of multi-amplifier parallel architecture

Abstract

The invention discloses a signal conditioning method for a field-grinding electric field sensor of a multi-amplifier parallel architecture. The signal conditioning method comprises the following steps: step 1, inputting a current signal acquired by an induction electrode of the field-grinding electric field sensor to an I-V conversion amplifier; 2, converting the input current signal into a corresponding voltage signal by the I-V conversion amplifier, and inputting the voltage signal to the parallel optimized amplifier; step 3, carrying out secondary amplification on the voltage signal by an amplifier optimized in parallel so as to improve the amplitude of the voltage signal, and carrying out noise suppression at the same time; step 4, connecting the signal subjected to secondary amplification to a phase-sensitive detection circuit, and outputting a detection voltage U0 by the phase-sensitive detection circuit; 5, the output voltage is kept stable through an integrating circuit, and then the signal is smoothed through a low-pass filter; through the steps, an output voltage signal in direct proportion to the external electric field Ex is finally obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric field sensing, in particular to a field grinding type electric field sensor based on a multi-amplifier parallel optimization architecture, which is particularly suitable for micro-current signal conditioning and high-precision measurement of the electric field under high-voltage direct current transmission lines. BACKGROUND

[0002] The direct current electric field is a key physical quantity in the ultra-high voltage direct current transmission system, and its accurate characterization is crucial for engineering application and safety protection. With the rapid development of high voltage level direct current transmission technologies such as ±800kV / ±1100kV, the spatially synthesized electric field intensity near the transmission corridor has significantly increased. This electric field is generated by the space ion flow from the high potential conductor and its corona discharge, which has a multi-level potential impact on the surrounding ecological environment, power facility reliability, and public health and safety.

[0003] Especially in the near region under the ultra / extra-high voltage direct current line, the electric field distribution has the characteristics of high non-uniformity, dynamics, and susceptibility to environmental interference, which is directly related to electromagnetic environment compliance evaluation, adjacent facility protection optimization, and operation safety guarantee. Therefore, obtaining high-precision, high-stability, and strong anti-interference field measurement data has become an urgent engineering requirement.

[0004] As a standard means of direct current electric field measurement, the core challenge of the field grinding type sensor is the high-fidelity conditioning of the pA~nA level micro-current signal. This weak signal is easily overwhelmed by circuit noise, temperature drift, and external electromagnetic interference, which is the main bottleneck restricting the measurement accuracy. Breaking through this micro-current low-noise conditioning bottleneck is the key to improving the performance of the sensor, and is also the core problem that the present application technical solution aims to solve.

[0005] In the prior art, the invention patent: CN 119986169A "Local electric field measurement method and device based on field grinding type high voltage direct current electric field measuring instrument" discloses a local electric field measurement method and device based on a field grinding type high voltage direct current electric field measuring instrument, which reduces the instrument volume and reduces the instrument distortion interference to the electric field, realizes accurate measurement of the local direct current electric field strength in a small area, and dynamically adjusts the specific number of shielding sensors according to the actual size of the measured area, to accurately measure the specific target area. In the process of measuring the direct current electric field with the shielding sensor, the metal plug has the physical property of shielding electric charge. When the sensor is shielded by the metal plug, the induced electric charge is reduced, and the electric field cannot be effectively measured. The sensor that is not shielded by the metal plug accurately measures and records the electric charge on its surface according to the field grinding principle to obtain the measurement value. However, this scheme does not optimize the design of the measurement signal conditioning circuit, and has problems such as low signal-to-noise ratio and insufficient anti-interference ability, especially in complex electromagnetic environments, the stability is poor, and it is difficult to obtain high-precision continuous measurement results.

[0006] The application patent: CN 114062795A "An electric field sensor for realizing three-dimensional electric field measurement by adopting motor driving universal joint transmission" proposes an electric field sensor for realizing three-dimensional electric field measurement by adopting motor driving universal joint transmission. The device is based on a one-dimensional field grinding type electric field measurement structure, and a universal joint is used to connect the motor and the circular metal shielding sheet, so that the motor transmits power to the circular metal shielding sheet at an angle, so as to realize the rotation of the circular metal shielding sheet coaxial with the fixed circular metal sensing sheet, and the circular metal shielding sheet periodically shields the circular metal sensing sheet to generate induced current on the circular metal sensing sheet. Finally, three groups of the same universal joint transmission structure are arranged in three-dimensional directions respectively, the induced currents corresponding to the three-dimensional directions are obtained, and the induced currents in the three-dimensional directions are synthesized, so as to convert the three-dimensional to-be-measured electric field strength. However, the technology focuses on the expansion of the spatial dimension, and the structure is complex and large in size, which is not suitable for real-time measurement of single-direction high-precision electric field, and the noise influence in the amplification circuit is not effectively suppressed, which limits the measurement sensitivity and reliability. SUMMARY

[0007] Although the field grinding type electric field sensor is widely used in the field of direct current electric field measurement due to its non-contact measurement characteristics and simple structure, the existing electric field measurement system generally faces the problem of insufficient signal processing capability; especially in the environment with strong electromagnetic interference, the traditional signal conditioning circuit cannot effectively suppress noise, which significantly affects the stability and accuracy of the measurement results. In order to solve the above technical problems, the applicant proposes the present application.

[0008] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows: A field grinding electric field sensor signal conditioning method with multiple parallel amplifiers, comprising the following steps: Step 1: The current signal collected by the sensing electrode of the field grinding electric field sensor is input to an I-V conversion amplifier; Step 2: The I-V conversion amplifier converts the input current signal into a corresponding voltage signal, and inputs the voltage signal to a parallel optimized amplifier; Step 3: The parallel optimized amplifier performs secondary amplification on the voltage signal to improve the amplitude of the voltage signal and suppress noise; Step 4: The signal after secondary amplification is connected to a phase-sensitive detection circuit, and the phase-sensitive detection circuit outputs a detection voltage U0; Step 5: The output voltage is kept stable by an integration circuit, and then the signal is smoothed by a low-pass filter; Through the above steps, the external electric field E xProportional output voltage signal.

[0009] The final output voltage signal is transmitted to the PC through a signal transmission channel for data processing and analysis.

[0010] Obtaining external electric field E x The size is as follows: ; Wherein, is the area of the upper surface of the static grinding piece that is not shielded, is the dielectric constant in a vacuum, is the induced current generated on the induction electrode of the field grinding electric field sensor.

[0011] Induced current generated on the induction electrode of the field grinding electric field sensor is obtained by the following formula: ; Wherein, is the size of the charge on the upper surface of the grinding piece.

[0012] The structure of the parallel optimized amplifier is: The input signal is first introduced by the input port and simultaneously input to the non-inverting input terminals of the M first-stage operational amplifiers after distribution; in the inverting input terminals of each first-stage operational amplifier, a grounding resistor R 1 is connected, and a feedback resistor R 2 is connected between the inverting input terminal and the output terminal to form a feedback loop; then, the output terminals of all first-stage operational amplifiers are merged after passing through a resistor R 3, and then uniformly input to the inverting input terminal of the second-stage operational amplifier; a feedback resistor R 4 is arranged between the inverting input terminal and the output terminal of the second-stage operational amplifier to form a feedback circuit of the second-stage amplifier; at the same time, the non-inverting input terminal of the second-stage operational amplifier is directly grounded; the output terminal of the second-stage operational amplifier serves as the overall output terminal of the parallel amplifier circuit, which is used to connect to the next stage circuit to realize further transmission and processing of the signal; this circuit can effectively reduce circuit noise.

[0013] In the parallel optimized amplifier, by using M amplifiers in parallel, the input noise voltage of the system can be effectively reduced and the signal-to-noise ratio can be improved; the effective value of the input noise voltage of each amplifier is E n,in When the gain of the amplifier is A , the effective value of the output noise voltage is E n,out The relationship between the effective value of the input noise voltage and the output noise voltage is: ; According to the relationship, by connecting multiple amplifiers in parallel, the output noise voltage effective value can be reduced by proportion; after parallel connection, the output is buffered and stabilized again through the operational amplifier to ensure the consistency of the signal and obtain a set of low-noise and high-fidelity output signals.

[0014] The phase-sensitive detection circuit adjusts the phase of the to-be-detected signal and the power frequency reference signal to be consistent, so that the output after detection only retains the component with the same frequency and phase as the reference signal, thereby improving the signal-to-noise ratio; The detection voltage output by the phase-sensitive detection circuit is input into the integration circuit, the time average of the waveform after detection is obtained, and the approximate direct current amount proportional to the amplitude of the in-phase component is obtained, thereby suppressing the pulsation and high-frequency ripple introduced by the detection switch and stabilizing the working point of the later stage.

[0015] The integrator output is sent into the low-pass filter, and the residual detection ripple, harmonics and high-frequency noise caused by mechanical modulation are further suppressed to obtain a smooth, low-noise and convenient data acquisition voltage.

[0016] The I-V conversion amplifier realizes the conversion of current to voltage through the operational amplifier in the circuit, and then filters the high-frequency noise of the operational amplifier through the feedback capacitor to prevent self-oscillation of the circuit and enhance the stability of the system.

[0017] Through data processing of the obtained voltage signal, the specific parameters of the measured direct current synthetic electric field can be obtained through a direct proportional relationship.

[0018] Compared with the prior art, the present application has the following technical effects: 1) The present application proposes a signal conditioning circuit design method based on multi-amplifier parallel optimization, which constructs a low-noise high-gain front-end conditioning channel for the problems of weak electric field induction signal and easy noise interference. The structure is configured by connecting multiple amplifiers in parallel, combining the quantization model of input noise voltage effective value and channel number, realizing the optimal balance between amplification multiple and system noise power spectral density, thereby significantly improving the signal-to-noise ratio; 2) The present application further integrates I-V conversion, phase-sensitive detection, integration filtering and other modules to build an integrated signal processing link, ensuring that the signal maintains high fidelity and time domain stability in the amplification, detection and filtering stages. Experimental tests show that the conditioning circuit has excellent response consistency and anti-interference ability under different electric field intensity conditions, and the measurement output has good linear correlation and dynamic range; 3) The present application provides a new type of signal conditioning scheme with high sensitivity and high stability for electric field environment monitoring under high voltage direct current transmission system, which has strong practicality and popularization value; 4) The present application can significantly improve the accuracy of electric field measurement; the present application successfully solves the problem of large signal noise and low signal-to-noise ratio in the traditional electric field measurement system through the design of signal conditioning circuit based on multi-amplifier parallel optimization. In the environment of high electromagnetic interference, it can effectively suppress noise signals, thereby improving the accuracy of measurement results. This innovative technology significantly improves the reliability of electric field measurement in complex environments, especially in the monitoring of high-voltage direct current transmission systems and their surrounding environment, which can provide more accurate data support; 5) The present application can optimize the signal conditioning structure to enhance the stability of the system; the present application adopts the structure of parallel amplifiers, which reduces the noise amplification phenomenon caused by traditional amplifiers under high gain conditions. The design of parallel amplifiers optimizes the signal amplification process, so that the system can maintain stability while effectively reducing low-frequency noise. This makes the electric field measurement instrument provide more stable and continuous measurement data during long-term operation, especially suitable for power system monitoring and environmental measurement that requires high stability; 6) The present application can improve the system's ability to resist electromagnetic interference; the present application significantly improves the system's anti-interference ability through unique signal conditioning circuit design. In the complex electromagnetic environment of high-voltage direct current transmission lines, the present application can effectively avoid the influence of external electromagnetic interference, ensuring the high reliability of electric field strength measurement. This feature makes the present application have wide application prospects in the fields of power facilities, environmental monitoring, and safety evaluation. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described below in conjunction with the drawings and examples: Figure 1 is a schematic diagram of a field grinding type electric field measuring instrument of the present application; Figure 2 is a measurement signal conditioning principle structure diagram; Figure 3 is a parallel optimized amplifier principle; Figure 4 is a time domain waveform diagram of a non-amplifier parallel circuit; Figure 5 is a time domain waveform diagram of an amplifier parallel circuit; Figure 6 is a noise power spectrum diagram. DETAILED DESCRIPTION

[0020] As shown in Figure 1 , a field grinding electric field sensor signal conditioning method based on multi-amplifier parallel architecture includes the following steps: Step 1: The current signal collected by the sensing electrode of the field grinding electric field sensor is input to the I-V conversion amplifier; Step 2: The I-V conversion amplifier converts the input current signal into a corresponding voltage signal and inputs the voltage signal into the parallel-optimized amplifier; Step 3: The parallel-optimized amplifier performs secondary amplification on the voltage signal to increase the amplitude of the voltage signal while suppressing noise; Step 4: The signal after secondary amplification is input into the phase-sensitive detection circuit, and the phase-sensitive detection circuit outputs a detection voltage U0; Step 5: The output voltage is stabilized by the integration circuit, and then the signal is smoothed by the low-pass filter; Through the above steps, the output voltage signal proportional to the external electric field E x is finally obtained.

[0021] The final output voltage signal is transmitted to the PC through the signal transmission channel for data processing and analysis.

[0022] When the external electric field E x is obtained, the following formula is used: ; Wherein, is the area of the upper surface of the static grinding plate that is not shielded, is the dielectric constant in a vacuum, is the induced current generated on the sensing electrode of the field grinding electric field sensor.

[0023] The induced current generated on the sensing electrode of the field grinding electric field sensor is obtained by the following formula: ; Wherein, is the size of the charge on the upper surface of the grinding plate.

[0024] The structure of the parallel-optimized amplifier is as follows: The input signal is first introduced by the input port and simultaneously input to the non-inverting input terminals of the M first-stage operational amplifiers after distribution; in the inverting input terminals of each first-stage operational amplifier, a grounding resistor R 1 is connected, and a feedback resistor R 2 is connected between the inverting input terminal and the output terminal to form a feedback loop; then, the output terminals of all first-stage operational amplifiers are merged after passing through a resistor R 3, and then uniformly input to the inverting input terminal of the second-stage operational amplifier; a feedback resistor R4. The feedback circuit is formed to form a two-stage amplifier; at the same time, the non-inverting input terminal of the two-stage operational amplifier is directly grounded; the output terminal of the two-stage operational amplifier is used as the overall output terminal of the parallel amplifier circuit, and is connected to the next stage circuit to realize further transmission and processing of the signal; the circuit can effectively reduce the circuit noise.

[0025] In the parallel-optimized amplifier, by using multiple amplifiers in parallel, M the input noise voltage of the system can be effectively reduced and the signal-to-noise ratio can be improved; the effective value of the input noise voltage of each amplifier is E n,in When the gain of the amplifier is A , the effective value of the output noise voltage is E n,out The relationship between the effective value of the input noise voltage and the effective value of the output noise voltage is: ; According to the relationship, by using multiple amplifiers in parallel, the effective value of the output noise voltage can be reduced by ; after parallel connection, the operational amplifier is used again for buffering and stable output, so as to ensure the consistency of the signal and obtain a group of output signals with low noise and high fidelity.

[0026] The phase-sensitive detection circuit adjusts the phase of the to-be-measured signal to be consistent with the phase of the power frequency reference signal, so that only the component with the same frequency and phase as the reference signal is reserved in the output after detection, thereby improving the signal-to-noise ratio; The detection voltage output by the phase-sensitive detection circuit is input into the integration circuit, the time average of the waveform after detection is obtained, and the approximate direct current amount proportional to the amplitude of the in-phase component is obtained, thereby suppressing the pulsation and high-frequency ripple introduced by the detection switch and stabilizing the working point of the later stage.

[0027] The output of the integrator is sent to the low-pass filter, and the residual detection ripple, harmonics and high-frequency noise caused by mechanical modulation are further suppressed, and a smooth, low-noise and convenient data acquisition voltage is obtained.

[0028] The I-V conversion amplifier converts the current into voltage through the operational amplifier in the circuit, and then filters the high-frequency noise of the operational amplifier through the feedback capacitor, so as to prevent self-oscillation of the circuit and enhance the stability of the system.

[0029] Through data processing of the obtained voltage signal, the specific parameters of the measured direct current synthetic electric field can be obtained through the direct proportional relationship.

[0030] Embodiment: 1. The structural principle of the field grinding type electric field measuring instrument is as shown in Figure 1 .

[0031] Its electric field measuring probe is composed of dynamic and static grinding pieces, both of which are two symmetrical fan-shaped metal pieces with the same size and connected to the same rotating shaft. The dynamic grinding piece rotates with the uniform motor, and the static grinding piece remains fixed.

[0032] The field grinding electric field measuring instrument is placed in the electric field E, the uniform motor rotates and drives the dynamic grinding piece to rotate at a constant speed, then the contact area of the static grinding piece below with the electric field changes periodically. When the upper surface of the static grinding piece is not shielded, in order to ensure the consistency of the ground potential, a certain amount of charge will accumulate on the upper surface. When it is shielded, the accumulated charge will flow into the ground through the grounding resistor R.

[0033] When it is shielded, the amount of charge on the upper surface of the static grinding piece is determined by the following formula: ; In the formula, Q is the size of the charge on the upper surface of the grinding piece, ε is the dielectric constant in vacuum, E E is the electric field strength of the environment where the field grinding electric field measuring instrument is located, A is the area of the upper surface of the static grinding piece that is not shielded; After solving , the corresponding current can be calculated as: ; From the formula, we can know that: ; Therefore, it can be known that the field grinding electric field measuring instrument can measure the electric field strength in the environment by measuring the current signal on the static grinding piece.

[0034] 2. The signal conditioning circuit structure based on the parallel connection of amplifiers is shown in Figure 2 .

[0035] The signal conditioning circuit is composed of a field grinding electric field sensor, a pre-I-V amplifier, an amplifier A optimized by parallel connection, a switch synchronous detection PSD, an integrator I, a low-pass filter LPF and an optical encoder.

[0036] After the field grinding rotation, the current collected by the induction electrode has a positive correlation with the size of the ground synthetic electric field under the power transmission line. After modulation by the signal processing circuit, the corresponding electric field value can be obtained. The current signal is first converted into a corresponding voltage signal by an I-V conversion amplifier. However, the voltage amplitude after I-V conversion is still insufficient to meet the needs of the subsequent signal processing channel, so a parallel optimized amplifier is used for secondary amplification to improve the amplitude of the voltage signal and suppress noise. The amplified voltage signal is connected to a phase-sensitive detection circuit to obtain a detection voltage U0. Subsequently, the output voltage is stabilized by an integration circuit, and then smoothed by a low-pass filter, and finally an output voltage signal proportional to the external electric field is obtained. The signal is transmitted to the PC through the signal transmission channel for data processing and analysis. E x

[0037] 3. The principle of the parallel optimized amplifier in the circuit is shown in Figure 3

[0038] In a conventional signal conditioning circuit, in order to improve the sensitivity of the output voltage, the amplification factor is usually set to more than 100 times. However, a higher amplification factor not only amplifies the signal, but also amplifies the noise by the same proportion, resulting in no substantial improvement in signal-to-noise ratio. To solve this problem, this paper adopts the structure of parallel amplifiers, which effectively reduces noise and improves the signal-to-noise ratio and stability of the signal conditioning circuit using parallel technology.

[0039] In the design of parallel operational amplifiers, by using M amplifiers in parallel, the input noise voltage of the system can be effectively reduced and the signal-to-noise ratio can be improved. Let the input noise voltage effective value of each amplifier be E n,in When the gain of a single amplifier is A, the output noise voltage effective value E n,out is related to the input noise voltage effective value as follows: ; In the formula: E n,out is the output noise voltage effective value, A is the gain of a single amplifier, E n,in is the input noise voltage effective value of each amplifier, M is the number of amplifiers in parallel.

[0040] According to this relationship, by connecting multiple amplifiers in parallel, the output noise voltage effective value can be reduced by a factor of S en ​​, the input current noise power spectral density is S in , the sensor output impedance is Z D , the total noise power spectral density is S BN : ; In the formula, SBN is the total noise power spectral density, Sen is the input voltage noise power spectral density of the amplifier, Sin is the input current noise power spectral density, ZD is the sensor output impedance.

[0041] According to the formula, the voltage noise is reduced by the parallel number M, and the current noise increases with the increase of the parallel number M. However, since the improvement of the signal-to-noise ratio is mainly due to the suppression of the voltage noise, the effect of improving the signal-to-noise ratio and suppressing the signal noise can be finally achieved. In general, increasing the number of parallel amplifiers can effectively suppress the voltage noise, thereby improving the signal-to-noise ratio, and the power spectral density of the total background noise changes with the increase of the number of parallel amplifiers.

[0042] Considering the noise performance, economy and design complexity, four parallel amplifiers are finally selected as the final design scheme; this scheme can theoretically effectively reduce noise and improve signal-to-noise ratio, while maintaining a reasonable balance in cost and circuit complexity, meeting the actual application requirements.

[0043] Experimental verification: To verify the performance of the amplifier signal conditioning circuit optimized by parallel connection, a noise test was conducted, and a comparative experiment was conducted with a conventional signal conditioning circuit. The noise test platform includes a field grinding type electric field measuring instrument test machine, a direct current voltage source, a signal conditioning module, an oscilloscope and a display screen, which are respectively used for outputting signals, powering the device, signal acquisition and data analysis.

[0044] Through the experiment, the time domain waveform is as shown in Figure 4 and Figure 5 From the figure, it can be seen that the voltage signal fluctuation range of the amplifier without parallel optimization is about 1.5~2.5V, and the voltage signal range of the amplifier with parallel optimization is about 1.9~2.1V. It can be seen that the stability of the conditioning circuit with amplifier parallel optimization is better.

[0045] Then, power spectrum analysis was conducted on the two groups of data shown in Figure 4 and Figure 5 , as shown in Figure 6As shown, the noise power spectral density of the signal conditioning circuit adopting the amplifier parallel optimization is obviously lower than that of the traditional signal conditioning circuit, which shows that the noise reduction effect of the signal conditioning circuit is obviously improved after the amplifier parallel optimization.

[0046] In order to establish the corresponding relationship between the measured voltage and the electric field intensity, the field mill type electric field measuring instrument is subjected to accurate calibration experiment by using a polar plate calibration device, and the device can accurately control and measure the size of the electric field.

[0047] According to the formula: ; In the formula, E E is the electric field size, U V is the measured voltage of the polar plate calibration device, d D is the distance between the two polar plates of the polar plate calibration device.

[0048] It can be seen that the electric field size between the upper and lower polar plates can be changed by changing the applied voltage size U , and then the function relationship between the electric field and the measured voltage can be obtained by comparing and calculating the voltage value measured by the field mill type electric field sensor with the calculated value of the electric field. The data obtained in the experiment are as shown in the table: Table 1 Electric field size and measured voltage comparison table

[0049] In the table, E E is the electric field intensity, U out V is the output voltage value of the field mill type electric field measuring instrument.

[0050] The corresponding relationship between the electric field E and the output voltage can be obtained by linear fitting by the least square method: ; When the output voltage is obtained, the electric field intensity can be obtained by calculation.

[0051] In summary, The application adopts a multi-channel low-noise amplifier parallel structure design: the application first introduces a multi-channel amplifier parallel architecture in the electric field measurement signal conditioning, effectively reduces the total noise power spectral density of the system by sharing the input signal path noise source in an average way, and significantly improves the signal-to-noise ratio of the system while ensuring the stability of the gain, and provides a hardware foundation for high-fidelity transmission of weak signals. The application of the field grinding structure periodic shielding type charge induction principle in the application: the application adopts the periodic shielding structure constructed by the dynamic and static grinding pieces, the induction area is changed by rotating in the uniform electric field, the periodic modulation of the electric charge is realized, and the alternating current induction current signal is generated.The principle converts the static electric field into a adjustable dynamic electric signal, has the advantages of non-contact, high stability, high sensitivity and the like, and is suitable for direct current field strength measurement; The application constructs a two-stage amplification and synchronous detection integrated signal path: the signal link constructed by the application comprises a first amplification module composed of an I-V converter and a parallel amplifier, and a complete conditioning channel composed of a synchronous detector, an integrator and a low-pass filter, so that the amplitude extraction, stable output and high-frequency interference suppression of the signal are realized.The integrated design improves the overall integration and response efficiency of the measurement system.

[0052] Amplification factor and channel number balance optimization design method: in view of the contradiction between signal intensity and noise tolerance in different application scenarios, the application provides an optimization configuration strategy of adjustable amplification factor and amplifier channel number.Through the establishment of the gain and noise square density relationship model, the optimal balance between performance, cost and energy consumption of the system is realized, and good engineering scalability is achieved.

[0053] High-impedance sensor interface and amplifier input stage impedance matching mechanism: considering the high output impedance characteristic of the field grinding sensor, the application designs a high input impedance amplifier front-end circuit adapted to the high output impedance characteristic, through the matching of the input stage impedance and the sensor impedance, the energy reflection and signal loss are effectively reduced, the signal coupling efficiency and the system measurement sensitivity are improved, and the precision closed loop of the overall measurement chain is guaranteed.

Claims

1. A method for conditioning the signal of a field mill electric field sensor with a multi-amplifier parallel architecture, characterized in that, Includes the following steps: Step 1: Current signal acquired by the sensing electrode of the field-milled electric field sensor Input to IV conversion amplifier; Step 2: The IV conversion amplifier converts the input current signal into a corresponding voltage signal and inputs the voltage signal to the parallel-optimized amplifier; Step 3: The voltage signal is amplified a second time by a parallel optimized amplifier to increase the amplitude of the voltage signal and suppress noise at the same time; Step 4: The signal after secondary amplification is input into the phase-sensitive detection circuit, and the phase-sensitive detection circuit outputs the detection voltage U0; Step 5: The output voltage is kept stable by an integrator circuit, and then the signal is smoothed by a low-pass filter; The above steps ultimately yield the result related to the external electric field. E x The output voltage signal is proportional to the voltage signal.

2. The method according to claim 1, characterized in that, The final output voltage signal is transmitted to the PC through the signal transmission channel for data processing and analysis.

3. The method according to claim 1, characterized in that, Obtaining external electric field E x When the size is specified, the following formula is used: ； in, This represents the unmasked area of ​​the upper surface of the grinding disc. Let be the dielectric constant in a vacuum. This refers to the induced current generated on the sensing electrode of the field-milled electric field sensor.

4. The method according to claim 3, characterized in that, The induced current generated on the sensing electrode of the field-milled electric field sensor Obtained from the following formula: ； in, This represents the magnitude of the surface charge on the grinding disc.

5. The method according to any one of claims 1 to 4, characterized in that, The structure of the parallel-optimized amplifier is as follows: The input signal is first introduced through the input port, and after being distributed, is simultaneously input to... M The non-inverting input of each stage operational amplifier is connected to the inverting input; a grounding resistor is connected to the inverting input of each stage operational amplifier. R 1. Simultaneously connect a feedback resistor between the inverting input terminal and the output terminal. R 2. This forms a feedback loop; subsequently, the outputs of all first-stage operational amplifiers are connected via resistors. R After merging, the inputs are uniformly fed to the inverting input terminal of the second-stage operational amplifier; a feedback resistor is provided between this inverting input terminal and the output terminal of the second-stage operational amplifier. R 4. To form the feedback circuit of the second-stage amplifier; at the same time, the non-inverting input terminal of the second-stage operational amplifier is directly grounded; the output terminal of the second-stage operational amplifier serves as the overall output terminal of the parallel amplifier circuit, used to connect to the next stage circuit to realize further signal transmission and processing.

6. The method according to claim 5, characterized in that, In parallel-optimized amplifiers, by... M Using multiple amplifiers in parallel can effectively reduce the system's input noise voltage and improve the signal-to-noise ratio; let the effective value of the input noise voltage of each amplifier be... E n,in When the amplifier gain is A At that time, the effective value of the output noise voltage E n,out The relationship with the effective value of the input noise voltage is as follows: ； Based on this relationship, by connecting multiple amplifiers in parallel, the effective value of the output noise voltage can be calculated according to... The proportion is reduced; after parallel connection, the output is buffered and stabilized again by operational amplifier to ensure signal consistency and obtain a set of low noise and high fidelity output signals.

7. The method according to claim 1, 2, 3, 4, or 6, characterized in that, The phase-sensitive detection circuit adjusts the phase of the signal under test to match that of the power frequency reference signal, so that the output after detection retains only the component that is in phase and frequency with the reference signal, thereby improving the signal-to-noise ratio. The detection voltage output from the phase-sensitive detector circuit is input into the integrator circuit, and the waveform after detection is averaged over time to obtain an approximate DC quantity that is proportional to the amplitude of the in-phase component. This suppresses the pulsation and high-frequency ripple introduced by the detector switch and stabilizes the operating point of the subsequent stage.

8. The method according to claim 7, characterized in that, The integrator output is fed into a low-pass filter to further suppress residual detector ripple, harmonics from mechanical modulation, and high-frequency noise, resulting in a smooth, low-noise voltage that is easy to acquire data.

9. The method according to claim 1, 2, 3, 4, or 6, characterized in that, The IV conversion amplifier converts current to voltage through an operational amplifier in the circuit, and then uses a feedback capacitor to filter out high-frequency noise from the operational amplifier, preventing the circuit from generating self-excited oscillations and enhancing the stability of the system.

10. The method according to claim 1, 2, 3, 4, 6, or 8, characterized in that, By processing the obtained voltage signal, the specific parameters of the measured DC composite electric field can be obtained through a direct proportional relationship.

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