CN113992188A - Electrode impedance matching circuit for measuring earth electric field - Google Patents
Electrode impedance matching circuit for measuring earth electric field Download PDFInfo
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- CN113992188A CN113992188A CN202111288929.5A CN202111288929A CN113992188A CN 113992188 A CN113992188 A CN 113992188A CN 202111288929 A CN202111288929 A CN 202111288929A CN 113992188 A CN113992188 A CN 113992188A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/28—Impedance matching networks
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Abstract
The application provides an electrode impedance matching circuit of earth electric field measurement, relates to the geophysical exploration field, includes: blocking capacitor and matching resistor connected in series with electrode grounding resistor, further comprising: and the non-inverting input end of the operational amplifier is in short circuit with the output end of the operational amplifier and serves as an output signal output end of the matching resistor. An operational amplifier for impedance matching is added between a receiving electrode and a receiver, the problem of unstable signals caused by large ground resistance is overcome through a circuit, the signals are ensured not to be attenuated, and stable ground electric field signals are picked up.
Description
Technical Field
The invention relates to the field of geophysical exploration, in particular to an electrode impedance matching circuit for measuring a geoelectric field.
Background
The resistivity method, the induced polarization method, the magnetotelluric method, the controllable source audio magnetotelluric method and the deep well electric field detection in the ground electromagnetic method all need to observe electric field components, usually the frequency range observed by the ground electromagnetic method is 0.0001-10kHz, the electric field component measurement is generally carried out by embedding a receiving electrode into the ground and connecting the receiving electrode with an observation system through a lead. The ground resistance of the receiving electrode in a soil humid environment is small, generally less than several hundred ohms, electric field component measurement can be normally carried out, in a high-resistance area, such as a desert arid area, a semi-arid area and a rock mass exposed area, the ground resistance is too large due to water shortage, generally more than 1M omega, and an electric field signal cannot be observed due to limited input impedance of an observation system. Scholars at home and abroad make many researches on the problem of the grounding resistance, Zonge et al (1985) research the influence of the resistance under a uniform medium model on the acquisition of high-frequency signals of an electric field of a controllable source audio magnetotelluric sounding method; thomas also investigated the effect of the magnitude of the ground impedance on complex resistivity measurements; zhang Youshan et al studied the influence of the magnitude of the ground resistance on the electric field in 1993 and proposed a series of improvement methods; the Li Ru theory based on Zonge provides the influence of the size of the ground resistance on the high frequency of the Carnia resistivity; the influence of the grounding resistance on an electric field of the audio magnetotelluric sounding method is researched through theories and field experiments in the Tangjing field; the Wanghui etc. proved the influence of the size of the ground resistance on the magnetotelluric sounding method by field test.
The previous research results show that when the grounding resistance is larger, the frequency range influenced by the electric field observation is wider, the descending amplitude is larger, namely the grounding resistance is larger than 5k omega, the frequency influenced by the electric field observation gradually tends to low frequency from 10kHz, the local resistance is 1M omega, and the data quality from 10kHz to 57Hz is influenced, so that the accuracy and the quality of the electric field data acquisition are influenced by the larger grounding resistance.
Disclosure of Invention
The present invention proposes an electrode impedance matching circuit for earth electric field measurement in an attempt to solve or at least alleviate the above existing problems.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
the invention provides an electrode impedance matching circuit for measuring a ground electric field, which comprises: blocking capacitor and matching resistor connected in series with electrode grounding resistor, further comprising: and the non-inverting input end of the operational amplifier is in short circuit with the output end of the operational amplifier and serves as an output signal output end of the matching resistor.
Optionally, the electrode grounding resistor has a resistance of 1k Ω -10M Ω.
Optionally, the electrode ground resistance has a resistance of 50k Ω.
Optionally, the capacitance value of the blocking capacitor is 1 μ F-10 μ F.
Optionally, the capacitance value of the blocking capacitor is 1 μ F.
Optionally, the matching resistor has a resistance value of 10k-100k Ω.
Optionally, the matching resistor has a resistance of 10k Ω.
Optionally, the input impedance of the operational amplifier is greater than 10M Ω, the bandwidth gain is greater than 1MHz, the offset voltage is less than 0.1mV, the offset current is less than 10pA, and the bias current is less than 10 pA.
Compared with the prior art, the invention has the following beneficial effects:
the electrode impedance matching circuit for measuring the earth electric field takes an electrode for receiving an electric field signal as a control device, an operational amplifier for impedance matching is added between the receiving electrode and a receiver, the problem of signal instability caused by large ground resistance is solved through the circuit, the signal is ensured not to be attenuated, and the stable earth electric field signal is picked up. The method is suitable for the electromagnetic measurement of arid and semiarid desert regions and rock mass exposed regions in deserts, can greatly reduce the working strength and the economic cost, also improves the measurement efficiency, and has strong practicability and wide application prospect.
Drawings
FIG. 1 is a schematic diagram of an electrode impedance matching circuit for earth electric field measurement of an embodiment of the present invention;
fig. 2 is a schematic diagram of the frequency characteristic of the circuit transfer function according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description of the embodiments of the present invention with reference to the accompanying drawings is provided, and it should be noted that, in the case of conflict, features in the embodiments and the embodiments in the present application may be arbitrarily combined with each other.
As shown in fig. 1, an embodiment of the present invention provides an electrode impedance matching circuit for a ground electric field measurement, including: and electrode grounding resistance RgSeries-connected blocking capacitor CcAnd a matching resistance Rf, further comprising: the non-inverting terminal Vp of the operational amplifier and the output terminal of the operational amplifier are connected in parallel to the matching resistor RfAnd the inverting input end of the operational amplifier is in short circuit with the output end of the operational amplifier and serves as an output signal output end Vo of the matched resistor.
In order to solve the impedance matching problem and ensure that signals are not attenuated, the embodiment of the invention adopts the electrode impedance matching circuit shown in fig. 1. Wherein R isgIs the ground resistance of the electrode, CcIs a blocking capacitor, RfIs a matched resistance. Vi is the electrode input signal, Vo is the output signal of the matching circuit, and Vp is the non-inverting terminal signal of the operational amplifier.
In the embodiment of the present invention, if the amplifier in fig. 1 is ideal, then Vp is Vo, and:
where s ═ jw, w is the angular frequency, and s denotes the complex field;
from the above formula one can obtain:
Vi＝Vp＝Vo
the output is shown to follow the input regardless of the electrode's ground resistance.
In practical application scenarios, due to the existence of bias voltage, bias current and offset current in the operational amplifier, Vo and Vp have a very large deviation Δ, and at this time:
from the above formula one can obtain:
for very low frequency conditions close to dc, the output signal of the matching circuit is:
at this time, the input quantity is attenuated, the output quantity is smaller than the input quantity, and the frequency is increased until sCc(Rg-Rf)>>At 1, the output signal of the matching circuit is:
in the embodiment of the invention, the output quantity follows the input quantity along with the increase of the frequency, and is not influenced by the grounding resistance.
Optionally, the electrode ground resistor has a resistance of 1k Ω to 10M Ω, and in the embodiment of the present invention, the electrode ground resistor preferably has a resistance of 50k Ω.
Optionally, a capacitance value of the blocking capacitor is 1 μ F to 10 μ F, and in the embodiment of the present invention, the capacitance value of the blocking capacitor is preferably 1 μ F.
Optionally, the resistance of the matching resistor is 10k-100k Ω, and in the embodiment of the present invention, the resistance of the matching resistor is preferably 10k Ω.
Optionally, the input impedance of the operational amplifier is greater than 10M Ω, the bandwidth gain is greater than 1MHz, the offset voltage is less than 0.1mV, the offset current is less than 10pA, and the bias current is less than 10 pA.
Examples of the invention
In this embodiment, let the grounding resistance RgAre respectively 1k omega, 50k omega, 1M omega and 10M omega (the grounding resistance R is required by normal observationgNot more than 10k omega, Cc＝1μF，RfThe frequency characteristic of the circuit transfer function is shown in fig. 2 at 10k Ω. Ground resistance RgIncreasing from 1k omega to 10M omega, the output signal Vo of the electrode impedance matching circuit is completely coincident at 0-10kHz, i.e. the electrode output signal Vo is extracted without the ground resistance RgThe influence of (c). The signal is picked up without distortion between the frequency range of 0.001Hz and 10kHz, and when the frequency of the signal is less than 0.001Hz and between 0 Hz and 0.001Hz, the lower the frequency, the larger the attenuation, thereby realizing the purpose of isolating direct current. When the ground resistance RgThe low-frequency suppression capability of the sensor is weakened up to 10M omega (in special environments such as desert and the like), the high-frequency characteristic frequency is reduced to be close to 10kHz, and the bandwidth requirement of magnetotelluric detection is still met.
Although the embodiments of the present invention have been described above, the contents thereof are merely embodiments adopted to facilitate understanding of the technical aspects of the present invention, and are not intended to limit the present invention. Any person skilled in the art to which the invention pertains can, without departing from the core technical solution disclosed in the present invention, make
Modifications and variations are possible in form and detail of implementation, but the scope of protection of the invention is still subject to the scope of protection defined by the appended claims.
Claims (8)
1. An electrode impedance matching circuit for earth electric field measurement, comprising: blocking capacitor and matching resistor connected in series with electrode grounding resistor, further comprising: and the non-inverting input end of the operational amplifier is in short circuit with the output end of the operational amplifier and serves as an output signal output end of the matching resistor.
2. The electrode impedance matching circuit of claim 1, wherein: the resistance value of the electrode grounding resistor is 1k omega-10M omega.
3. The electrode impedance matching circuit of claim 1, wherein: the resistance value of the electrode grounding resistor is 50k omega.
4. The electrode impedance matching circuit of claim 1, wherein: the capacitance value of the blocking capacitor is 1 muF-10 muF.
5. The electrode impedance matching circuit of claim 1, wherein: the capacitance value of the blocking capacitor is 1 muF.
6. The electrode impedance matching circuit of claim 1, wherein: the resistance value of the matching resistor is 10k-100k omega.
7. The electrode impedance matching circuit of claim 1, wherein: the resistance value of the matching resistor is 10k omega.
8. The electrode impedance matching circuit of claim 1, wherein the input impedance of the operational amplifier is greater than 10M Ω, the bandwidth gain is greater than 1MHz, the offset voltage is less than 0.1mV, the offset current is less than 10pA, and the bias current is less than 10 pA.
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| CN202111288929.5A CN113992188A (en) | 2021-11-02 | 2021-11-02 | Electrode impedance matching circuit for measuring earth electric field |
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| CN202111288929.5A CN113992188A (en) | 2021-11-02 | 2021-11-02 | Electrode impedance matching circuit for measuring earth electric field |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201892707U (en) * | 2010-08-25 | 2011-07-06 | 重庆大学 | Measuring system for electric field |
| WO2014118565A2 (en) * | 2013-02-01 | 2014-08-07 | Rescon Limited | Signal stabilization in a dielectric sensor assembly |
| CN106970270A (en) * | 2017-05-26 | 2017-07-21 | 吉林大学 | A kind of long period seismic electrical signal acquisition system and measuring method |
| CN207882356U (en) * | 2018-01-19 | 2018-09-18 | 宁波三星智能电气有限公司 | A kind of fault detector applied to power distribution network |
| CN113406708A (en) * | 2021-06-18 | 2021-09-17 | 中国科学院地质与地球物理研究所 | Electrode range eliminating system and method for electromagnetic prospecting electric field measurement |
-
2021
- 2021-11-02 CN CN202111288929.5A patent/CN113992188A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201892707U (en) * | 2010-08-25 | 2011-07-06 | 重庆大学 | Measuring system for electric field |
| WO2014118565A2 (en) * | 2013-02-01 | 2014-08-07 | Rescon Limited | Signal stabilization in a dielectric sensor assembly |
| CN106970270A (en) * | 2017-05-26 | 2017-07-21 | 吉林大学 | A kind of long period seismic electrical signal acquisition system and measuring method |
| CN207882356U (en) * | 2018-01-19 | 2018-09-18 | 宁波三星智能电气有限公司 | A kind of fault detector applied to power distribution network |
| CN113406708A (en) * | 2021-06-18 | 2021-09-17 | 中国科学院地质与地球物理研究所 | Electrode range eliminating system and method for electromagnetic prospecting electric field measurement |
Non-Patent Citations (2)
| Title |
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| 张友山，何继善: "接地电阻对地电场观测的影响及克服方法", 《中国有色金属学报》 * |
| 王志宇等: "一种新型地球物理电容性电场传感器研究", 《仪器仪表学报》 * |
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