CN202854235U - Device for measuring solution conductivity by using two waveform excitation signals - Google Patents
Device for measuring solution conductivity by using two waveform excitation signals Download PDFInfo
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- CN202854235U CN202854235U CN 201220480001 CN201220480001U CN202854235U CN 202854235 U CN202854235 U CN 202854235U CN 201220480001 CN201220480001 CN 201220480001 CN 201220480001 U CN201220480001 U CN 201220480001U CN 202854235 U CN202854235 U CN 202854235U
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Abstract
The utility model provides a device for measuring solution conductivity by using two waveform excitation signals. The device is formed by a double waveform generator, a conductance cell, a signal conditioning circuit, a parameter detection circuit, an operation and control unit and a man-machine interface. The double waveform generator can produce two excitation signals with different waveforms, a generated first waveform excitation signal is used for calculating an electrode distribution capacitance, the electrode distribution capacitance obtained through calculation and a second waveform excitation signal generated by the double waveform generator are combined and are used for calculating the resistance and conductivity of solution. According to the scheme, dynamical measurement of the electrode distribution capacitance can be carried out, the influence of the electrode distribution capacitance and double-layer capacitance of an electrode on the measurement is eliminated, and the scheme is a reference scheme of the accurate measurement of the solution conductivity.
Description
Technical field
The utility model relates to the measurement mechanism of electrical conductivity of solution or resistivity, relates in particular to the measurement mechanism of the electrical conductivity of solution that adopts two kinds of waveform stimulus signals.
Background technology
The fundamental method of measurement of electrical conductivity of solution is the voltage U of measuring on the two ends that are applied to the electrode of inserting solution
DWith the electric current I that flows through electrode, calculate the resistance R=U between the electrode
D/ I, with the conductivity of G=K/R calculating solution, wherein K is electrode constant.But the electrode of inserting in the solution can produce polarization after energising, make the voltage U that records
DNot in fact the voltage at the two ends of solution own, but the electric double layer capacitance that is applied to solution resistance and relates to solution/metal electrode interface process is (hereinafter to be referred as the voltage on the virtual electronic device of these two series connection, so the formula R=U electric double layer capacitance of electrode)
DThere is theoretical error in/I; In order to reduce electrode polarization to the impact of accuracy of measurement, basic skills is the alternating current that applies the positive-negative polarity symmetry at electrode, but under ac-excited signal function, the electric current I that records not is the electric current that flows through merely solution, but flow through the total current of solution resistance branch circuit parallel connection distribution of electrodes electric capacity (comprising electrode interelectrode capacity, contact conductor electric capacity) branch road, therefore use ac-excited method when reducing the electrode polarization impact, but to introduce the impact of distribution of electrodes electric capacity on measuring.
The research of adopting electrochemical analysis method to measure electrical conductivity of solution at present all uses resistance-capacitance network as the conductance cell equivalent physical model, and these resistance-capacitance networks as the conductance cell equivalent physical model mainly are divided into two classes, the first kind is with detected solution resistance distribution of electrodes electric capacity in parallel, this is better simply model, the research institute that also is most electrical conductivity of solution tests aspect relates to, Equations of The Second Kind for the electric double layer capacitance of the electrode of connecting with detected solution resistance after distribution of electrodes electric capacity in parallel again, this is relative complex and more unmanageable model, referring to this Figure of description 1, it is the conductance cell equivalent physical model that is fit to precision measurement.The problem that mainly solves for the research take first kind resistance-capacitance network as the conductance cell equivalent physical model is to eliminate the impact of distribution of electrodes electric capacity, obtained in this respect a large amount of achievements in research, have and adopt phase sensitive detection, the dynamic pulse method of adopting is arranged, the method of double pulse measurement is arranged, adopt in addition the bifrequency square wave excitation etc. method, these achievements in research have obtained positive effect, but because used conductance cell equivalent physical model is not taken into account the electric double layer capacitance of electrode, naturally also just ignored the impact of electric double layer capacitance on measuring of electrode, the impact of the electric double layer capacitance of electrode can not be ignored in precision measurement, even the capacitive reactance of the electric double layer capacitance of electrode only has 1% size of detected solution resistance, just because of this, be restricted for the research of the first kind resistance-capacitance network model development to more precision measurement.
Realize the precision measurement of electrical conductivity of solution, require links all accurate as far as possible, comprise: 1, the resistance-capacitance network model of simulation conductance cell principle of work must be more near truth, according to the achievement in research of electrochemical analysis aspect, above-mentioned Equations of The Second Kind model (namely with behind the electric double layer capacitance of detected solution resistance series connection electrode again distribution of electrodes electric capacity in parallel) than first kind model (namely using detected solution resistance distribution of electrodes electric capacity in parallel) more near real conductance cell, more accurate; 2, the derivation of finding the solution mathematic(al) representation that is based upon on the resistance-capacitance network basis is accurate as far as possible, and is few approximate with preferably not existing; 3, mathematic(al) representation is that enclosed is found the solution rather than iterative as far as possible, mathematic(al) representation do not occur as far as possible denominator close to zero situation to avoid the amplification of error in numerical calculation; 4, carry out the numerical evaluation time error according to mathematic(al) representation as far as possible little; 5, the detection of electrode excitation signal and electrode response signal such as current value, magnitude of voltage, performance number equal error are as far as possible little.The 4th link is numerical evaluation theoretical category problem, specially refers to the input storage of numerical value and effective word length problem of calculating; The 5th link is the problem of circuit design aspect; The 1st ~ 3 environment is determined by overall plan, is the core of electrical conductivity of solution measurement scheme.At present also less based on the research of above-mentioned Equations of The Second Kind conductance cell equivalent physical model, especially yet there are no the calculation expression without approximate derivation of finding the solution electrical conductivity of solution based on Equations of The Second Kind conductance cell equivalent physical model, except the inventor herein once Chinese patent application number is the measuring method of disclosed a kind of electrical conductivity of solution in 200910113046.3 the application for patent.Claims in this patented method do not relate to the method for solving of distribution of electrodes electric capacity, be as the input parameter of finding the solution in the detected solution resistance expression formula distribution of electrodes electric capacity, and there are some defectives in the scaling method of the distribution of electrodes electric capacity of recommending in this patent specification, because when the conductivity of test solution, be full of detected solution between the conductance cell electrode, and the solution that is full of between the conductance cell electrode is equivalent to a kind of medium between the electrode pad, meeting as the specific inductive capacity of the detected solution of medium and air is variant, so the described distribution of electrodes electric capacity that places air acceptance of the bid location survey to go out at electrode of this patented method places the real distribution of electrodes electric capacity of detected solution to understand variant with electrode.One of purpose of the utility model patent is that a kind of of aforementioned patent replenished, the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing is proposed, this measurement mechanism comprises the pumping signal of two kinds of waveforms, the first waveform stimulus signal is used for measuring finds the solution distribution of electrodes electric capacity, and the second waveform stimulus signal is used for measuring finds the solution resistance and the conductivity of solution.
Summary of the invention
The purpose of this utility model provides a kind of electric double layer capacitance that can eliminate electrode and distribution of electrodes electric capacity (comprising electrode interelectrode capacity and contact conductor electric capacity) dual factors to the electrical conductivity of solution with two kinds of waveform stimulus signal characteristics of the adverse effect measured or the measurement mechanism of resistivity.
The technical scheme that realizes above-mentioned purpose is: adopt the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals, be comprised of double wave shape generator, conductance cell, signal conditioning circuit, parameter detecting circuit, computing and controller and 6 modules of man-machine interface; The function of each module and mutual connected mode are as follows:
Double wave shape generator can produce the pumping signal of two kinds of different wave, and the control that is subjected to computing and controller to be to determine the being moment that produces the first waveform stimulus signal or the second waveform stimulus signal and produce pumping signal, and the pumping signal that double wave shape generator produces exports the electrode of conductance cell to and this electrode is encouraged; The first waveform stimulus signal that double wave shape generator produces is used for measuring and calculating distribution of electrodes electric capacity, and the second waveform stimulus signal that the distribution of electrodes electric capacity that measuring and calculating obtains produces in conjunction with double wave shape generator is used for resistance and the conductivity of measuring and calculating solution;
Conductance cell includes electrode and detected solution, and the electrode that includes receives from the pumping signal of double wave shape generator generation and by its excitation, produces the electrode response signal and exports signal conditioning circuit to;
Signal conditioning circuit receives from the electrode response signal of conductance cell and to the electrode response signal and carries out filtering and signal amplification, filtering mode (logical such as low pass, high pass or band) and signal amplification factor are subjected to the control of computing and controller, and the output of signal conditioning circuit is connected to the parameter detecting circuit;
The control that the parameter detecting circuit is subjected to computing and controller is carried out parameter detecting (such as the instantaneous value of voltage, electric current, power or effective value etc.) and is exported the result of parameter detecting to computing and controller the signal from signal conditioning circuit;
The connection of computing and controller and function comprise 7 aspects: a, double wave shape generator are controlled to determine to produce the first waveform stimulus signal or the moment of the second waveform stimulus signal and generation pumping signal; B, signal conditioning circuit controlled to determine filtering mode and the signal amplification factor of signal conditioning circuit; C, the parameter detecting circuit controlled to determine to detect moment (such as the detection of instantaneous value constantly) of which kind of parameter and detected parameters; D, receive the output signal from the parameter detecting circuit; E, the signal from the parameter detecting circuit is carried out data operation process; F, the result of data calculation process is exported to man-machine interface show; G, receive the input (carrying out the parameter setting example of measurement mechanism as selecting conductivity measurement scope etc.) from man-machine interface;
Man-machine interface is connected with computing and controller, comprises the function of two aspects: a, the result who processes from the data operation of computing and controller is shown; B, the parameter that will arrange in the key-press input mode are sent into computing and controller.
Principle of the present invention:
Core concept of the present invention is to adopt the pumping signal of two kinds of waveforms, wherein uses the pumping signal of the first waveform to be convenient to calculate distribution of electrodes electric capacity, but is not easy to carry out the measuring and calculating of electrical conductivity of solution; In the situation that the known electrodes distributed capacitance uses the pumping signal of the second waveform to be convenient to calculate the conductivity of solution, but use the pumping signal of the second waveform to be not easy to calculate distribution of electrodes electric capacity; Be independent of the principle (being that distribution of electrodes electric capacity and excitation signal waveforms are irrelevant) of excitation signal waveforms based on distribution of electrodes electric capacity, two kinds of waveform stimulus signal combination are got up, make two kinds of waveform stimulus signals be opposite to respectively identical electrodes in the identical detected solution and carry out timesharing excitation and detecting electrode response signal, calculate with suitable expression formula, the distribution of electrodes electric capacity that the pumping signal measuring and calculating of using the first waveform is obtained is used for the expression formula of measuring and calculating electrical conductivity of solution of the pumping signal of use the second waveform.
The measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing of the present utility model is compared existing measuring method and had following beneficial effect: distribution of electrodes electric capacity can dynamic measurement, and its impact can be eliminated fully; The exciting signal frequency size is not had special requirement, can in relative broad range, select arbitrarily; When there is polarization in electrode and is embodied in the conductance cell equivalent physical model with the electric double layer capacitance of electrode, can quantitatively count its impact, be the reference technique scheme of accurately measuring electrical conductivity of solution.
Description of drawings
Fig. 1 is the equivalent physical model figure of conductance cell.
Fig. 2 is conductivity measuring apparatus figure;
Embodiment
Below in conjunction with accompanying drawing the technical solution of the utility model is further described:
Adopt the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals, formed by double wave shape generator (10), conductance cell (20), signal conditioning circuit (30), parameter detecting circuit (40), computing and controller (50) and (60) 6 modules of man-machine interface; The function of each module and mutual connected mode are as follows:
Double wave shape generator (10) can produce the pumping signal of two kinds of different wave, and the control that is subjected to computing and controller (50) to be to determine the being moment that produces the first waveform stimulus signal or the second waveform stimulus signal and produce pumping signal, and the pumping signal that double wave shape generator (10) produces exports the electrode of conductance cell (20) to and this electrode is encouraged; The first waveform stimulus signal that double wave shape generator (10) produces is used for measuring and calculating distribution of electrodes electric capacity, and the second waveform stimulus signal that the distribution of electrodes electric capacity that measuring and calculating obtains produces in conjunction with double wave shape generator (10) is used for resistance and the conductivity of measuring and calculating solution;
Conductance cell (20) includes electrode and detected solution, and the electrode that includes receives from the pumping signal of double wave shape generator (10) generation and by its excitation, produces the electrode response signal and exports signal conditioning circuit (30) to;
Signal conditioning circuit (30) receives from the electrode response signal of conductance cell (20) and to the electrode response signal and carries out filtering and signal amplification, filtering mode and signal amplification factor are subjected to the control of computing and controller (50), and the output of signal conditioning circuit (30) is connected to parameter detecting circuit (40);
The control that parameter detecting circuit (40) is subjected to computing and controller (50) is carried out parameter detecting and is exported the result of parameter detecting to computing and controller (50) the signal from signal conditioning circuit (30);
The connection of computing and controller (50) and function comprise 7 aspects: a, double wave shape generator (10) are controlled to determine it is to produce the first waveform stimulus signal or the moment of the second waveform stimulus signal and generation pumping signal; B, to signal conditioning circuit (30) control to determine filtering mode and the signal amplification factor of signal conditioning circuit (30); C, to parameter detecting circuit (40) control to determine to detect the moment of which kind of parameter and detected parameters; D, receive the output signal from parameter detecting circuit (40); E, the signal from parameter detecting circuit (40) is carried out data operation process; F, the result of data calculation process is exported to man-machine interface (60) show; G, receive the input from man-machine interface (60);
Man-machine interface (60) is connected with computing and controller (50), comprises the function of two aspects: a, the result who processes from the data operation of computing and controller (50) is shown; B, the parameter that will arrange in the key-press input mode are sent into computing and controller (50).
Embodiment one:
Functional module and connected mode are with the description of above-mentioned embodiment to technical scheme, the first waveform stimulus signal adopt to exchange symmetric triangular wave voltage signal, and (polarity that exchanges crest that the symmetric triangular ripple refers to refer to triangular wave and trough is opposite, amplitude equal, upper wave band equates with the slope absolute value of lower wave band), the second waveform stimulus signal adopts the sinusoidal voltage signal.The electrical conductivity of solution measurement procedure of the described measurement mechanism of technical solutions of the utility model is as follows:
Electrode is placed detected solution, electrode is encouraged as the first waveform stimulus signal with exchanging symmetric triangular wave voltage signal, the detecting electrode response current, calculate distribution of electrodes electric capacity with suitable calculation expression, electrode is remained in the detected solution, electrode is comprised that contact conductor do not do the movement of any physical location, electrode is encouraged as the second waveform stimulus signal with the sinusoidal voltage signal, the active power of detecting electrode response current and consumption of electrode calculates resistance and the conductivity of solution in conjunction with the distribution of electrodes electric capacity that has recorded with suitable calculation expression.
The term that above embodiment is used, symbol are not construed as limiting application of the present utility model, just for convenience of explanation.Those skilled in the art can make some replacements according to embodiment of the present utility model, yet these all equivalences of doing according to the utility model embodiment are replaced and are revised, and belong to invention thought of the present utility model and reach in the claim that is defined by claim.
Claims (7)
1. adopt the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals, formed by double wave shape generator (10), conductance cell (20), signal conditioning circuit (30), parameter detecting circuit (40), computing and controller (50) and (60) 6 modules of man-machine interface; It is characterized in that comprising double wave shape generator (10), double wave shape generator (10) can produce the pumping signal of two kinds of different wave, the first waveform stimulus signal that produces is used for measuring and calculating distribution of electrodes electric capacity, and the second waveform stimulus signal that the distribution of electrodes electric capacity that measuring and calculating obtains produces in conjunction with double wave shape generator (10) is used for resistance and the conductivity of measuring and calculating solution.
2. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1, it is characterized in that: described double wave shape generator (10) is subjected to the control of computing and controller (50) to determine being to produce the first waveform stimulus signal or the moment of the second waveform stimulus signal and generation pumping signal, and the pumping signal that double wave shape generator (10) produces exports the electrode of conductance cell (20) to and this electrode is encouraged.
3. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1, it is characterized in that: described conductance cell (20) includes electrode and detected solution, the electrode that includes receives from the pumping signal of double wave shape generator (10) generation and by its excitation, produces the electrode response signal and exports signal conditioning circuit (30) to.
4. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1, it is characterized in that: described signal conditioning circuit (30) receives from the electrode response signal of conductance cell (20) and to the electrode response signal and carries out filtering and signal amplification, filtering mode and signal amplification factor are subjected to the control of computing and controller (50), and the output of signal conditioning circuit (30) is connected to parameter detecting circuit (40).
5. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1 is characterized in that: the control that described parameter detecting circuit (40) is subjected to computing and controller (50) is carried out parameter detecting and is exported the result of parameter detecting to computing and controller (50) the signal from signal conditioning circuit (30).
6. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1 is characterized in that: the connection of described computing and controller (50) and function comprise 7 aspects: a, to double wave shape generator (10) control to determine the being moment that produces the first waveform stimulus signal or the second waveform stimulus signal and produce pumping signal; B, to signal conditioning circuit (30) control to determine filtering mode and the signal amplification factor of signal conditioning circuit (30); C, to parameter detecting circuit (40) control to determine to detect the moment of which kind of parameter and detected parameters; D, receive the output signal from parameter detecting circuit (40); E, the signal from parameter detecting circuit (40) is carried out data operation process; F, the result of data calculation process is exported to man-machine interface (60) show; G, receive the input from man-machine interface (60).
7. the measurement mechanism of the electrical conductivity of solution of two kinds of waveform stimulus signals of employing as claimed in claim 1, it is characterized in that: described man-machine interface (60) is connected with computing and controller (50), comprises the function of two aspects: a, the result who processes from the data operation of computing and controller (50) is shown; B, the parameter that will arrange in the key-press input mode are sent into computing and controller (50).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220480001 CN202854235U (en) | 2012-09-19 | 2012-09-19 | Device for measuring solution conductivity by using two waveform excitation signals |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201220480001 CN202854235U (en) | 2012-09-19 | 2012-09-19 | Device for measuring solution conductivity by using two waveform excitation signals |
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| CN 201220480001 Expired - Fee Related CN202854235U (en) | 2012-09-19 | 2012-09-19 | Device for measuring solution conductivity by using two waveform excitation signals |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067893A (en) * | 2015-08-19 | 2015-11-18 | 大连理工大学 | Solution resistance soft measurement method based on conductance cell second-order system model |
| CN108761209A (en) * | 2018-07-19 | 2018-11-06 | 浙江维思无线网络技术有限公司 | A kind of liquid electric conductivity measurement method and device |
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2012
- 2012-09-19 CN CN 201220480001 patent/CN202854235U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067893A (en) * | 2015-08-19 | 2015-11-18 | 大连理工大学 | Solution resistance soft measurement method based on conductance cell second-order system model |
| CN105067893B (en) * | 2015-08-19 | 2017-10-17 | 大连理工大学 | Solution resistance flexible measurement method based on conductance cell second order model |
| CN108761209A (en) * | 2018-07-19 | 2018-11-06 | 浙江维思无线网络技术有限公司 | A kind of liquid electric conductivity measurement method and device |
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Granted publication date: 20130403 Termination date: 20150919 |
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