A water conductivity sensor and a water conductivity measurement method

Abstract

The present invention relates to a water quality conductivity sensor and a water quality conductivity measurement method, and relates to the technical field of water quality conductivity. The water quality conductivity sensor includes a plurality of measuring electrodes, and one measuring electrode includes a transmitting electrode sheet and a receiving electrode sheet that are relatively arranged and have the same size and shape, and the transmitting electrode sheets between the measuring electrodes are of the same size and shape; the transmitting electrode sheet is connected to a sinusoidal wave excitation signal source, and the receiving electrode sheet and the sinusoidal wave excitation signal source share a common ground, and one measuring electrode corresponds to one sinusoidal wave excitation signal source. The present invention can effectively suppress electrode polarization and reduce the influence on the sinusoidal signal, thereby improving the measurement accuracy of water quality conductivity parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of water conductivity, and in particular to a water conductivity sensor and a water conductivity measuring method. Background Art

[0002] With the continuous development of science and technology, serious environmental pollution problems have also been brought about while the times are progressing. Among them, water resource pollution is the most serious, and the impact range is also larger and wider. In order to solve the problem of water resource environmental pollution, the first thing to consider is the measurement and collection of water quality parameters, so as to further confirm the water source pollution situation. Among various water quality parameters, the conductivity parameter is the most important. The conductivity of the aqueous solution indicates the concentration of the solute salt contained in it. The purer the water, the lower the conductivity.

[0003] Traditional electrode-type conductivity sensors have a small number of electrode plates, making it difficult to separate the voltage electrode and the current electrode. Therefore, they have a relatively serious electrode polarization effect, which will greatly affect the accurate measurement of conductivity parameters. In order to further improve the measurement accuracy of conductivity sensors, it is necessary to improve the structural design and measurement method of the sensor, and adopt a measurement method with higher accuracy while being able to suppress the polarization of the electrode. Summary of the invention

[0004] The purpose of the present invention is to provide a water conductivity sensor and a water conductivity measurement method, which can effectively suppress electrode polarization and reduce the influence on sinusoidal signals, thereby improving the measurement accuracy of water conductivity parameters.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A water quality conductivity sensor comprises: a plurality of measuring electrodes, wherein one measuring electrode comprises a transmitting electrode sheet and a receiving electrode sheet of the same size and shape which are arranged relatively to each other, and the transmitting electrode sheets between the measuring electrodes are of the same size and shape; the transmitting electrode sheet is connected to a sinusoidal wave excitation signal source, the receiving electrode sheet and the sinusoidal wave excitation signal source share a common ground, and one measuring electrode corresponds to one sinusoidal wave excitation signal source.

[0007] Optionally, the water quality conductivity sensor includes two measuring electrodes, namely a first measuring electrode and a second measuring electrode, the emitting electrode sheet in the first measuring electrode and the emitting electrode sheet in the second measuring electrode are in the same plane and are arranged vertically, the emitting electrode sheet in the second measuring electrode and the receiving electrode sheet are respectively distributed on both sides of the first measuring electrode, and the emitting electrode sheet in the first measuring electrode, the receiving electrode sheet in the first measuring electrode, the emitting electrode sheet in the second measuring electrode and the receiving electrode sheet in the second measuring electrode are distributed in a centrally symmetrical manner.

[0008] Optionally, the emitting electrode sheet is in an arc shape.

[0009] Optionally, the emitting electrode sheet is in a rectangular shape.

[0010] Optionally, the electrode sheet is made of platinum material, alloy material, carbon material or ceramic material.

[0011] Optionally, the sinusoidal wave excitation signal of the emitting electrode sheet in the first measuring electrode and the sinusoidal wave excitation signal of the emitting electrode sheet in the second measuring electrode are 90 degrees out of phase with each other.

[0012] Optionally, the water quality conductivity sensor also includes: a controller, which is respectively connected to each of the sinusoidal wave excitation signal sources and each of the receiving electrode sheets, and is used to control the sinusoidal wave excitation signal source to generate an excitation voltage signal of a set phase, and calculate the water quality conductivity based on the AC current signal received by the receiving electrode sheet.

[0013] A method for measuring water conductivity, applied to the water conductivity sensor described above, the method comprising:

[0014] Acquiring the alternating current signal received by each receiving electrode sheet and the excitation voltage signal emitted by each sinusoidal wave excitation signal source;

[0015] Determining parameter constants according to the alternating current signals received by each of the receiving electrode sheets and the excitation voltage signals emitted by each of the sinusoidal wave excitation signal sources;

[0016] Obtaining a DC signal according to the AC current signal received by each receiving electrode sheet and a vector transformation matrix;

[0017] The water conductivity is determined according to the DC signal and the parameter constant.

[0018] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: a water quality conductivity sensor of the present invention comprises: a plurality of measuring electrodes, one measuring electrode comprises a transmitting electrode sheet and a receiving electrode sheet of the same size and shape which are relatively arranged, and the transmitting electrode sheets between the measuring electrodes are of the same size and shape; the transmitting electrode sheet is connected to a sinusoidal wave excitation signal source, the receiving electrode sheet shares a common ground with the sinusoidal wave excitation signal source, one measuring electrode corresponds to one sinusoidal wave excitation signal source, and the independent operation of the plurality of measuring electrodes can effectively suppress the electrode polarization effect and reduce the influence on the sinusoidal signal, thereby improving the measurement accuracy of the water quality conductivity parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 A schematic diagram of the structure of a four-electrode water conductivity sensor provided in an embodiment of the present invention;

[0021] Figure 2 It is a working equivalent schematic diagram of a four-electrode water conductivity sensor;

[0022] Figure 3 is a schematic diagram of the excitation signal waveform;

[0023] Figure 4 Schematic diagram of the received signal waveform. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The purpose of the present invention is to propose a structure of a water quality conductivity sensor and a corresponding conductivity measurement method in view of the inevitable electrode polarization effect of the existing electrode-type conductivity sensor, which can effectively suppress the influence of the electrode polarization effect, improve the measurement accuracy of the conductivity to a certain extent, and is suitable for most high-precision water quality conductivity parameter measurement systems. The water quality conductivity sensor comprises: a plurality of measuring electrodes, one measuring electrode comprises a transmitting electrode sheet and a receiving electrode sheet which are relatively arranged and have the same size and shape, and the transmitting electrode sheets between the measuring electrodes are the same in size and shape; the transmitting electrode sheet is connected to a sinusoidal wave excitation signal source, the receiving electrode sheet and the sinusoidal wave excitation signal source share a common ground, and one measuring electrode corresponds to one sinusoidal wave excitation signal source.

[0027] As an optional implementation, when there are two measuring electrodes, the water quality conductivity sensor includes four electrode sheets, namely two transmitting electrode sheets and two receiving electrode sheets. Figure 1As shown, the two measuring electrodes are respectively a first measuring electrode and a second measuring electrode, the emitting electrode sheet in the first measuring electrode and the emitting electrode sheet in the second measuring electrode are in the same plane and are vertically arranged, the emitting electrode sheet in the second measuring electrode and the receiving electrode sheet are respectively distributed on both sides of the first measuring electrode, and the emitting electrode sheet in the first measuring electrode, the receiving electrode sheet in the first measuring electrode, the emitting electrode sheet in the second measuring electrode and the receiving electrode sheet in the second measuring electrode are distributed in a centrally symmetrical manner, wherein the shape of the emitting electrode sheet is an arc or a rectangle, and its numerical value can be appropriately adjusted according to actual needs, but the size and shape of the four electrode sheets should be the same.

[0028] As an optional implementation, the material of the electrode sheet is platinum material, alloy material, carbon material or ceramic material, and platinum is generally used as the raw material.

[0029] As an optional implementation manner, the excitation voltage signal of the emitting electrode sheet in the first measuring electrode and the excitation voltage signal of the emitting electrode sheet in the second measuring electrode are 90 degrees out of phase with each other.

[0030] As an optional embodiment, the water quality conductivity sensor also includes: a controller, which is respectively connected to each of the sinusoidal wave excitation signal sources and each of the receiving electrode sheets, and is used to control the sinusoidal wave excitation signal source to generate an excitation voltage signal of a set phase, and calculate the water quality conductivity based on the AC current signal received by the receiving electrode sheet.

[0031] The embodiment of the present invention further provides a method for measuring water conductivity applied to the above-mentioned water conductivity sensor, the method comprising:

[0032] The alternating current signal received by each receiving electrode sheet and the excitation voltage signal emitted by each sinusoidal wave excitation signal source are acquired.

[0033] The parameter constant is determined according to the alternating current signal received by each of the receiving electrode sheets and the excitation voltage signal emitted by each of the sinusoidal wave excitation signal sources.

[0034] A direct current signal is obtained according to the alternating current signal received by each receiving electrode sheet and a vector transformation matrix.

[0035] The water conductivity is determined according to the DC signal and the parameter constant.

[0036] In practical applications, when the AC current signals received by each receiving electrode sheet are i1 and i2, and the known excitation voltage signals applied are u1 and u2, the parameter constants are determined according to the AC current signals received by each receiving electrode sheet and the excitation voltage signals emitted by each sinusoidal wave excitation signal source, specifically including:

[0037] Process according to the following formula and obtain the parameter constant C:

[0038] C=u1i1+u2i2

[0039] In practical applications, determining the water conductivity according to the DC signal and the parameter constant specifically includes:

[0040] According to the DC signal, the equivalent impedance R of the solution can be obtained. z :

[0041]

[0042] Where V m is the amplitude of the applied excitation voltage signal, which can further determine the water conductivity:

[0043]

[0044] Where κ is the conductivity and k is the cell constant.

[0045] The embodiment of the present invention provides a working process when the water quality conductivity sensor includes four electrode sheets, namely two transmitting electrode sheets and two receiving electrode sheets. The four electrode sheets are divided into two groups, each group is composed of a transmitting electrode sheet and a receiving electrode sheet, and the two electrode sheets are arranged opposite to each other. The shape of the electrode sheets can be rectangular or arc-shaped, and the arrangement method thereof corresponds to a square arrangement or a circular arrangement, respectively. Figure 1 As shown in (a) and (b), the electrode sheets are numbered from top to bottom and from left to right, that is, ① and ③ are a pair of electrodes, ② and ④ are another pair of measuring electrodes, among which ① and ② are transmitting electrode sheets as transmitters, and ③ and ④ are receiving electrode sheets as receivers.

[0046] like Figure 2 As shown, when measuring conductivity, the microcontroller controls the programmable waveform generator to send out two excitation voltage signals u1 and u2 with the same amplitude and frequency and a phase difference of 90° (u1 is 90° ahead of u2), and the operational amplifier actively amplifies the signal, and sends it out through the two emitters of the sensor to excite the solution to be tested. After the excitation voltage signals u1 and u2 of the system pass through the solution to be tested, due to the impedance effect of the solution, the excitation voltage signals u1 and u2 will be received as i1 and i2 at the receiving electrode in the form of current signals respectively. The sinusoidal excitation voltage signal and the received signal are shown as follows: Figure 3 and Figure 4After the current signals i1 and i2 pass through the signal conditioning circuit, the microcontroller processes the data information. The data processing method is a new AC orthogonal vector water quality conductivity parameter measurement method. The microcontroller performs vector transformation processing on the sinusoidal current signals i1 and i2 received by two different receiving poles, establishes a two-phase stationary coordinate system with i1 and i2, and projects it into the synchronous rotating coordinate system to obtain the corresponding current quantity i α and i β , the vector transformation matrix is ​​as follows:

[0047]

[0048] Where θ is the angle between the two-phase stationary coordinate system and the synchronous rotating coordinate system.

[0049] Through this vector transformation, the sinusoidal AC signal can be converted into a DC signal. By processing the DC signal, the signal data of the sinusoidal AC signal at any time point can be utilized, avoiding the disadvantage that the traditional measurement method can only perform data analysis and processing at the peak of the sinusoidal signal. By improving the conductivity measurement system from the measurement principle, the measurement accuracy of the conductivity can be greatly improved, thereby obtaining more accurate data.

[0050] The beneficial effects of the present invention are:

[0051] 1. The multi-electrode structure design of the conductivity sensor can effectively suppress the electrode polarization effect and reduce its influence on the measurement signal; the normal operation of the relatively independent measuring electrodes can greatly improve the measurement error caused by accidental factors under the working state. Thus, the measurement accuracy of water conductivity parameters can be improved, which can be applied to high-precision measurement systems.

[0052] 2. The excitation voltage signals emitted by two independent excitation sources respectively excite the solution to be tested, which reduces the measurement error caused by a single excitation voltage signal on the one hand; on the other hand, the current signal obtained after the two excitation voltage signals with a phase difference of 90° pass through the solution to be tested, although the amplitude and phase of the excitation voltage signal will change due to the impedance effect of the solution, the two signals will still maintain a phase difference of 90° because they change under the action of the same solution. By using a new AC vector measurement method, the single-phase AC signal can be vector transformed, the AC quantity can be converted into a DC quantity, and data analysis and processing can be performed on this basis, which can avoid the disadvantage that the traditional measurement method can only perform data analysis and processing at the peak of the sinusoidal signal, thereby obtaining more accurate and comprehensive data information.

[0053] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0054] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A water conductivity sensor, characterized in that: include: A plurality of measuring electrodes, wherein one measuring electrode comprises a transmitting electrode sheet and a receiving electrode sheet which are arranged relatively to each other and have the same size and shape, and the transmitting electrode sheets between the measuring electrodes have the same size and shape; The transmitting electrode sheet is connected to a sine wave excitation signal source, the receiving electrode sheet and the sine wave excitation signal source share a common ground, and one measuring electrode corresponds to one sine wave excitation signal source; The multiple measuring electrodes are two measuring electrodes, namely a first measuring electrode and a second measuring electrode. The emitting electrode sheet in the first measuring electrode and the emitting electrode sheet in the second measuring electrode are in the same plane and are vertically arranged. The emitting electrode sheet in the second measuring electrode and the receiving electrode sheet are respectively distributed on both sides of the first measuring electrode, and the emitting electrode sheet in the first measuring electrode, the receiving electrode sheet in the first measuring electrode, the emitting electrode sheet in the second measuring electrode and the receiving electrode sheet in the second measuring electrode are distributed in a centrally symmetrical manner.

2. A water conductivity sensor according to claim 1, characterized in that: The shape of the emitting electrode piece is arc-shaped.

3. A water conductivity sensor according to claim 1, characterized in that: The shape of the emitting electrode piece is rectangular.

4. A water conductivity sensor according to claim 1, characterized in that: The electrode sheet is made of platinum material, alloy material, carbon material or ceramic material.

5. A water conductivity sensor according to claim 1, characterized in that: The excitation voltage signal of the emitting electrode sheet in the first measuring electrode and the excitation voltage signal of the emitting electrode sheet in the second measuring electrode are out of phase by 90 degrees.

6. A water conductivity sensor according to claim 1, characterized in that: Also includes: A controller, wherein the controller is connected to each of the sinusoidal wave excitation signal sources and each of the receiving electrode sheets respectively, and the controller is used to control the sinusoidal wave excitation signal source to generate an excitation voltage signal of a set phase, and calculate the water conductivity according to the AC current signal received by the receiving electrode sheets.

7. A method for measuring water conductivity, characterized in that: The method applied to the water conductivity sensor according to any one of claims 1 to 6 comprises: The microcontroller controls the programmable waveform generator to generate two excitation voltage signals with the same amplitude and frequency and a phase difference of 90°. and , Compare Leading 90°, and through the operational amplifier and Active amplification is performed, and the solution to be tested is emitted through two transmitting electrodes of the water conductivity sensor and stimulated; Acquiring the alternating current signal received by each receiving electrode sheet and the excitation voltage signal emitted by each sinusoidal wave excitation signal source; Determining parameter constants according to the alternating current signals received by each of the receiving electrode sheets and the excitation voltage signals emitted by each of the sinusoidal wave excitation signal sources; The DC signal is obtained according to the AC current signal received by each receiving electrode sheet and the vector transformation matrix; specifically, the microcontroller converts the AC current signals received by two different receiving electrode sheets into and Perform vector transformation processing to and Establish a two-phase stationary coordinate system and project it into the synchronous rotating coordinate system to obtain the corresponding current and , the vector transformation matrix is ​​as follows: In the formula, is the angle between the two-phase stationary coordinate system and the synchronous rotating coordinate system; Determine water conductivity according to the DC signal and the parameter constant; The parameter constant is determined according to the AC current signal received by each receiving electrode sheet and the excitation voltage signal emitted by each sinusoidal wave excitation signal source, specifically: according to the formula Calculate the parameter constant, where C represents the parameter constant, represents the excitation voltage signal emitted by the sinusoidal excitation signal source connected to the transmitting electrode in the first measuring electrode, represents the excitation voltage signal emitted by the sinusoidal excitation signal source connected to the transmitting electrode in the second measuring electrode, Indicates the AC current signal received by the receiving electrode sheet in the first measuring electrode, Represents the AC current signal received by the receiving electrode sheet in the second measuring electrode.

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