Conductivity sensor and conductivity measurement method

Abstract

The application relates to the technical field of seawater detection, and provides a conductivity sensor and a conductivity measurement method.The sensor comprises: an excitation magnetic ring with an excitation coil and a compensation coil wound around a magnetic core, two ends of the excitation coil are used for applying an excitation signal, and the compensation coil is used for outputting a self-induction signal; an induction magnetic ring with an induction coil wound around the magnetic core; a flow guide pipe arranged between the excitation magnetic ring and the induction magnetic ring, used for passing through a to-be-detected liquid, so that the induction coil outputs an induction signal; a conditioning and extraction circuit used for performing voltage amplitude extraction processing on the self-induction signal and the induction signal after conditioning, determining a first voltage amplitude and a second voltage amplitude; and a compensation circuit used for determining the conductivity of the to-be-detected liquid based on the first voltage amplitude, a reference voltage amplitude of a compensation coil output signal of the excitation magnetic ring at a reference temperature and the second voltage amplitude, and ensuring the reference value of the measurement result of the sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seawater detection, and particularly relates to a conductivity sensor and a conductivity measurement method. BACKGROUND

[0002] The conductivity sensor adopts coaxially arranged excitation magnetic rings and induction magnetic rings, and a flow guide pipe is arranged between the excitation magnetic rings and the induction magnetic rings. In actual work, the conductivity sensor is immersed in a to-be-measured liquid, the to-be-measured liquid flows through the excitation magnetic rings and the induction magnetic rings through the flow guide pipe, which is equivalent to connecting a liquid equivalent resistance Rc in series between the excitation magnetic rings and the induction magnetic rings; due to the electromagnetic induction effect, the induction magnetic rings generate an induction signal, i.e., a receiving signal S1, which is related to the conductivity of the to-be-measured liquid flowing between the excitation magnetic rings and the induction magnetic rings. After the receiving signal S1 is conditioned and amplified, a signal S2 is obtained, the amplitude of the signal S2 is linearly related to the conductivity of the to-be-measured liquid, and the signal S2 is AD sampled (i.e., converted from an analog quantity to a digital quantity), and the sampling result enters an MCU (Microcontroller Unit), and the conductivity of the to-be-measured liquid can be obtained through calculation.

[0003] However, temperature changes will have a great influence on the measurement result of the conductivity. On the one hand, the magnetic permeability of the magnetic ring will change with the temperature, thereby affecting the receiving signal S1; on the other hand, the temperature change will also affect the intermediate circuit such as the conditioning and amplification circuit, thereby affecting the signal S2.

[0004] At present, nanocrystals or permalloy with small temperature change of magnetic permeability are usually selected to manufacture the magnetic ring, and resistors and capacitors with low temperature drift and chips are selected on the measurement circuit as much as possible, so as to reduce the influence of temperature change on the measurement.

[0005] However, the measurement accuracy of the above-mentioned method needs to be improved. SUMMARY

[0006] The present application provides a conductivity sensor and a conductivity measurement method, which compensates the voltage amplitude or conductivity of the output signal of the compensation coil caused by the temperature change, compensates the voltage amplitude or conductivity corresponding to the output signal of the induction coil, and ensures the reference value of the measured conductivity.

[0007] In a first aspect, the present application provides a conductivity sensor, comprising:

[0008] An excitation magnetic ring, a magnetic core of which is wound with an excitation coil and a compensation coil, two ends of the excitation coil are applied with an excitation signal, so that the compensation coil outputs a self-induction signal, and the self-induction signal is used to reflect the magnetic field of the excitation magnetic ring at the current temperature;

[0009] An induction magnetic ring, a magnetic core of which is wound with an induction coil;

[0010] A flow guide tube is disposed between the excitation magnetic ring and the induction magnetic ring to allow the liquid to be measured to pass through, so that the induction coil outputs an induction signal.

[0011] The conditioning and extraction circuit is used to condition the self-inductance signal and the induced signal respectively and then extract the voltage amplitude to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induced signal.

[0012] The compensation circuit is used to determine a first amplitude error based on the first voltage amplitude and the reference voltage amplitude of the compensation coil output signal of the excitation magnetic ring at a reference temperature; to determine the relationship between the second amplitude error and the second voltage amplitude based on the relationship between the first amplitude error and the first voltage amplitude to solve for the second amplitude error; to correct the second voltage amplitude based on the second amplitude error; and to solve for the conductivity based on the corrected second voltage amplitude, the voltage amplitude, and the conductivity to determine the conductivity of the liquid to be tested.

[0013] In a second aspect, the present invention provides a conductivity sensor, comprising:

[0014] An excitation magnetic ring has an excitation coil and a compensation coil wound around its core. An excitation signal is applied to both ends of the excitation coil to cause the compensation coil to output a self-inductance signal. The self-inductance signal is used to reflect the magnetic field of the excitation magnetic ring at the current temperature.

[0015] An induction magnetic ring has an induction coil wound around its magnetic core.

[0016] A flow guide tube is disposed between the excitation magnetic ring and the induction magnetic ring to allow the liquid to be measured to pass through, so that the induction coil outputs an induction signal.

[0017] The conditioning and extraction circuit is used to condition the self-inductance signal and the induced signal respectively and then extract the voltage amplitude to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induced signal.

[0018] A compensation circuit is used to solve for conductivity based on the relationship between voltage amplitude and conductivity, to determine a first conductivity corresponding to the first voltage amplitude and a second conductivity corresponding to the second voltage amplitude; to determine a first conductivity error based on the first conductivity and a reference conductivity corresponding to the output signal of the compensation coil of the excitation magnetic ring at a reference temperature; to determine a second conductivity error based on the relationship between the first conductivity error and the first conductivity, and to solve for the second conductivity error; and to correct the second conductivity based on the second conductivity error to determine a third conductivity of the liquid to be tested.

[0019] Thirdly, the present invention provides a conductivity measurement method applied to a conductivity sensor, the conductivity sensor comprising an excitation magnetic ring with an excitation coil and an induction coil sleeved on a magnetic core, an induction magnetic ring with an induction coil sleeved on a magnetic core, and a guide tube between the excitation magnetic ring and the induction magnetic ring, wherein the method comprises:

[0020] An excitation signal is applied to the excitation coil to obtain the self-inductance signal output by the compensation coil;

[0021] When the guide tube passes through the liquid to be tested, the induced signal output by the induction coil is acquired;

[0022] After conditioning the self-inductance signal and the induction signal respectively, the voltage amplitude is extracted to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induction signal;

[0023] The first amplitude error is determined based on the first voltage amplitude and the reference voltage amplitude of the compensation coil output signal of the excitation magnetic ring at the reference temperature;

[0024] Based on the relationship between the first amplitude error and the first voltage amplitude, the relationship between the second amplitude error and the second voltage amplitude is determined to solve for the second amplitude error;

[0025] The second voltage amplitude is corrected based on the second amplitude error;

[0026] The conductivity is determined by solving the relationship between the corrected second voltage amplitude, voltage amplitude, and conductivity.

[0027] Fourthly, the present invention provides a conductivity measurement method applied to a conductivity sensor, the conductivity sensor comprising an excitation magnetic ring with an excitation coil and an induction coil sleeved on a magnetic core, an induction magnetic ring with an induction coil sleeved on a magnetic core, and a guide tube between the excitation magnetic ring and the induction magnetic ring, wherein the method comprises:

[0028] An excitation signal is applied to the excitation coil to obtain the self-inductance signal output by the compensation coil;

[0029] When the guide tube passes through the liquid to be tested, the induced signal output by the induction coil is acquired;

[0030] After conditioning the self-inductance signal and the induction signal respectively, the voltage amplitude is extracted to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induction signal;

[0031] The conductivity is calculated based on the relationship between voltage amplitude and conductivity, and the first conductivity corresponding to the first voltage amplitude and the second conductivity corresponding to the second voltage amplitude are determined.

[0032] The first conductivity error is determined based on the first conductivity and the reference conductivity corresponding to the output signal of the compensation coil of the excitation magnetic ring at the reference temperature.

[0033] Based on the relationship between the first conductivity error and the first conductivity, the relationship between the second conductivity error and the second conductivity is determined to solve for the second conductivity error;

[0034] The third conductivity of the liquid to be tested is determined by correcting the second conductivity error based on the second conductivity error.

[0035] Fifthly, the present invention provides a computer-readable storage medium including execution instructions that, when executed by a conductivity sensor, perform the method described in any of the third or fourth aspects.

[0036] This invention provides a conductivity sensor and a conductivity measurement method. By utilizing the change in voltage amplitude or conductivity of the output signal of the compensation coil caused by temperature changes, the voltage amplitude or conductivity corresponding to the output signal of the induction coil is compensated, ensuring the reference value of the measured conductivity.

[0037] The further effects of the aforementioned non-conventional preferred method will be explained below in conjunction with specific embodiments. Attached Figure Description

[0038] To more clearly illustrate this embodiment or existing technical solution, the drawings used in the description of the embodiment or existing technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of the structure of the conductivity sensor provided in an embodiment of the present invention. Figure 1 ;

[0040] Figure 2 A schematic diagram of the structure of the conductivity sensor provided in an embodiment of the present invention. Figure 2 ;

[0041] Figure 3 A flowchart illustrating the conductivity measurement method provided in this embodiment of the invention. Figure 1 ;

[0042] Figure 4 A flowchart illustrating the conductivity measurement method provided in this embodiment of the invention. Figure 2 ;

[0043] Figure 5 A schematic diagram of the structure of the conductivity sensor provided in an embodiment of the present invention. Figure 3 . Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] like Figure 1 As shown and Figure 2 The diagram shown is a structural schematic of a conductivity sensor provided in this embodiment. In this embodiment, the conductivity sensor includes: an excitation magnetic ring 1, with an excitation coil 11 and a compensation coil 12 wound around its core. An excitation signal is applied to both ends of the excitation coil 11 to cause the compensation coil 12 to generate a self-inductance signal, which reflects the magnetic field condition of the excitation magnetic ring 1 at the current temperature; an induction magnetic ring 2, with an induction coil 21 wound around its core; a flow guide 3, disposed between the excitation magnetic ring 1 and the receiving magnetic ring, wherein when the liquid to be measured passes through the flow guide and an excitation signal is applied to the excitation coil 11, the induction coil 21 outputs an induction signal; and a conditioning and extraction circuit 4, used to condition and extract the self-inductance signal and... After conditioning, the voltage amplitude is extracted to determine the first voltage amplitude corresponding to the self-induced signal and the second voltage amplitude corresponding to the induced signal. The compensation circuit 5 is used to compensate the reference voltage amplitude and / or reference conductivity corresponding to the output signal of the excitation magnetic ring 12 at the reference temperature based on the excitation magnetic ring 1. The relationship between the first voltage amplitude and the second voltage amplitude is used to analyze the relationship between the change from the reference temperature to the current temperature on the excitation magnetic ring 1 and the induction magnetic ring 2, so as to compensate the conductivity or voltage amplitude corresponding to the output signal of the induction coil 21 and determine the conductivity of the liquid to be measured.

[0046] In this embodiment, the conductivity or voltage amplitude corresponding to the second induction signal generated by the induction coil 21 is corrected by the first induction signal generated by the compensation coil 12, thereby reducing the influence of temperature drift and ensuring the accuracy of the conductivity measured by the conductivity sensor.

[0047] Temperature changes significantly impact the measurement results (i.e., conductivity) of conductivity sensors. On one hand, the permeability of the magnetic ring changes with temperature, affecting the output current of the coil wound around the magnetic core. On the other hand, temperature changes also affect the voltage amplitude extraction circuit (i.e., the aforementioned conditioning and extraction circuit 4), thus influencing the voltage amplitude extraction result. In this embodiment, to reduce the impact of temperature changes on conductivity measurement results, firstly, nanocrystalline or permalloy alloys with low permeability variation with temperature are typically selected to fabricate the excitation magnetic ring 1 and the induction magnetic ring 2. In practical applications, the excitation magnetic ring 1 and the induction magnetic ring 2 can be selected from the same manufacturer, made of the same material, and from the same batch, with low permeability variation with temperature. Secondly, low-temperature drift resistors, capacitors, and chips are used as much as possible in the voltage amplitude extraction circuit (i.e., the aforementioned conditioning and extraction circuit 4) to reduce the impact of temperature changes on the circuit to a certain extent, thereby ensuring the reference value of the voltage amplitude measurement results.

[0048] In actual operation, the conductivity sensor is immersed in the liquid to be measured, and the guide tube 3 passes through the liquid, which is equivalent to connecting a liquid equivalent resistance Rc in series between the excitation magnetic ring 1 and the induction magnetic ring 2. Due to the electromagnetic induction effect, an induced current is generated in the induction magnetic ring 2. The excitation coil 11 and the compensation coil 12 are wound around the excitation magnetic ring 1. A changing current is applied to the excitation coil 11 wound around the excitation magnetic ring 1, thereby causing the compensation coil 12 to output a self-induced signal. Since the output signal of the compensation coil 12 corresponds to a specific conductivity, which does not change, under the same conditions of excitation magnetic ring 1 and induction magnetic ring 2 and the same temperature, the effect of temperature change on excitation magnetic ring 1 and induction magnetic ring 2 is related. Therefore, the change in voltage amplitude or conductivity of the output signal of the compensation coil 12 under temperature change can be used to compensate for the conductivity corresponding to the induced signal generated by the induction coil 21. It is worth noting that because the conductivity sensor is immersed in the liquid for a long time, the temperature of the induction magnetic ring 2 and the excitation magnetic ring 1 is the same.

[0049] It should be noted that the conductivity sensor needs to be calibrated before it will work. The specific calibration process is as follows:

[0050] In practical applications, at temperature T1, the conductivity sensor acquires the voltage amplitude A1 of the self-induced signal generated by the compensation coil 12 and the voltage amplitude B1 of the induced signal generated by the induction coil 21 in a water tank (containing a calibration liquid with a conductivity of C1). Then, the conditioning extraction circuit 4 is adjusted so that A1 = B1, thus obtaining the conductivity C1 corresponding to the output signal of the compensation coil 12. In one possible implementation, the conductivity C1 can be the maximum conductivity of the liquid being measured, such as the maximum conductivity of seawater. As a feasible implementation, temperature T1 can be understood as a reference temperature, such as room temperature.

[0051] The relationship between conductivity and voltage amplitude provided in this embodiment will be explained below.

[0052] In practical applications, the conductivity sensor acquires the voltage amplitudes A1 and A2 of the output signal from the induction coil 21 in constant-temperature water baths with conductivity values ​​C1 and C2, respectively. Then, in the liquid to be measured with conductivity Cx, the voltage amplitude of the output signal from the induction coil 21 is Ax. Considering the linear relationship between voltage amplitude and conductivity, therefore... Furthermore, the conductivity Cx of the liquid to be tested can be calculated using formula (1):

[0053]

[0054] Where C1, C2, A1, and A2 are all constants.

[0055] It is worth noting that the conductivity sensor includes a probe and a main body. The flow guide tube 3, the excitation magnetic ring 1, and the induction magnetic ring 2 are all located inside the probe, while the conditioning extraction circuit 4 and the compensation circuit 5 are located inside the main body.

[0056] As a feasible implementation method, the signal output from both ends of the compensation coil 12 is used as a self-inductance signal.

[0057] In practical applications, the output signal at one end of the compensation coil 12 is used as the self-inductance signal, and the other end is connected to the ground wire.

[0058] As a feasible implementation method, the signal output from both ends of the induction coil 21 is used as the induction signal.

[0059] In practical applications, the signal output from one end of the induction coil 31 is used as the induction signal, and the other end is connected to the ground wire.

[0060] As a feasible implementation method, the excitation signal is provided by the compensation circuit 5.

[0061] As a feasible implementation, the conditioning and extraction circuit 4 is used to extract the same voltage amplitude after conditioning the self-inductance signal and the induction signal respectively, thereby reducing the impact of temperature changes on the circuit to a certain extent and ensuring the reference value of the voltage amplitude extraction result.

[0062] In one example, the conditioning extraction circuit 4 includes: a first conditioning circuit 41 for performing first conditioning on the self-inductance signal to determine a first voltage signal; a second conditioning circuit 42 for performing second conditioning on the inductance signal to determine a second voltage signal; and an amplitude extraction circuit 43 for performing the same voltage amplitude extraction processing on the first voltage signal and the second voltage signal to determine the first voltage amplitude corresponding to the first voltage signal and the second voltage amplitude corresponding to the second voltage signal.

[0063] Optionally, the first conditioning step can be voltage division. It should be noted that, considering that the self-inductance signal generated by self-induction is a voltage signal, and the voltage amplitude of this signal is too large, it does not meet the input voltage requirements of the amplitude extraction circuit 43. Therefore, voltage division is required.

[0064] Optionally, the second conditioning can be voltage signal conversion processing. It should be noted that, considering that the induced signal generated by the induction coil 21 is a current signal, it is necessary to convert the current signal into a voltage signal to meet the voltage input requirements of the subsequent amplitude extraction circuit 43.

[0065] Optionally, the amplitude extraction circuit 43 includes: a signal selection circuit 431, used to take one of the second voltage signal and the first voltage signal as an input signal; an amplification circuit 432, used to amplify the input signal and determine the amplified voltage signal corresponding to the input signal; an amplitude analog signal extraction circuit 433, used to extract the amplitude of the amplified voltage signal and determine the voltage amplitude analog signal; and a digital sampling circuit 434, used to convert the voltage amplitude analog signal into a voltage amplitude; wherein, when the input signal is the first voltage signal, the voltage amplitude output by the digital sampling circuit 434 is the first voltage amplitude; and when the input signal is the second voltage signal, the voltage amplitude output by the digital sampling circuit 434 is the second voltage amplitude.

[0066] Here, in order to ensure the accuracy of the extracted voltage amplitude, and considering that the voltage amplitudes of the first voltage signal and the second voltage signal are relatively small, and that the difference between small voltage amplitudes may lead to a large difference in conductivity, reducing the measurement accuracy, it is also necessary to meet the voltage input requirements of the digital sampling circuit 434. Therefore, the amplifier circuit 432 is needed to amplify the self-inductance signal and the induced signal to ensure the reference value of the extracted voltage amplitude.

[0067] Considering that temperature will affect the amplification of amplifier circuit 432, in order to reduce the impact, amplitude extraction circuit 43 processes the first circuit signal and the second voltage signal in the same way, so as to ensure the accuracy of the extracted voltage amplitude.

[0068] Furthermore, the processing circuit is used to determine the first sampling frequency and the second sampling frequency; wherein the first sampling frequency is greater than the second sampling frequency; the signal selection circuit 431 is used to select the first voltage signal as the input signal based on the first sampling frequency; and to select the second voltage signal as the input signal based on the second sampling frequency.

[0069] Considering that temperature change is a slow process, the sampling frequency of the self-inductance signal of the compensation coil 12 can be appropriately reduced to reduce the amount of data processing to a certain extent and ensure the calculation speed of the conductivity sensor.

[0070] In addition, the compensation circuit 5 obtains the first voltage amplitude output by the conditioning extraction circuit 4, but does not obtain the second voltage amplitude output by the conditioning extraction circuit 4 within the set time period (because the signal selection circuit 431 does not select the second voltage signal). It substitutes the first voltage amplitude into the above formula (1) to calculate the conductivity as the conductivity of the liquid to be tested.

[0071] As a feasible implementation, the compensation circuit 5 is used to determine the first amplitude error based on the first voltage amplitude and the reference voltage amplitude of the output signal of the compensation coil 12 at the reference temperature of the excitation magnetic ring 1; to determine the relationship between the second amplitude error and the first voltage amplitude based on the relationship between the first amplitude error and the first voltage amplitude to solve for the second amplitude error; to correct the second voltage amplitude based on the second amplitude error; and to solve for the conductivity based on the corrected second voltage amplitude, the voltage amplitude and the conductivity to determine the conductivity of the liquid to be measured.

[0072] It should be noted that the reference voltage amplitude can be understood as the voltage amplitude output by the compensation coil 12 after processing by the conditioning and extraction circuit 4 at the reference temperature. The first amplitude error reflects the effect of the change in reference temperature to the current temperature on the excitation magnetic ring 1, resulting in a change in the voltage amplitude of the compensation coil 12 output signal. The second amplitude error reflects the effect of the change in reference temperature to the current temperature on the induction magnetic ring 2, resulting in a change in the voltage amplitude of the induction coil 21 output signal.

[0073] In this embodiment, the excitation magnetic ring and the induction magnetic ring are the same, and the relationship between the first amplitude error and the first voltage amplitude is equal to the relationship between the second voltage amplitude and the second amplitude error.

[0074] The second amplitude error calculation process provided in this embodiment will be explained below.

[0075] In practical applications, at temperature T1, the voltage amplitude of the self-inductance signal generated by the compensation coil 12 in a water tank with conductivity C1 is A1, and the voltage amplitude of the induced signal generated by the induction coil 21 is B1. At temperature T2, due to the influence of temperature on the magnetic ring, when measuring again in a water tank with conductivity C1, the voltage amplitude of the self-inductance signal generated by the compensation coil 12 is A1', and the voltage amplitude of the induced signal generated by the induction coil 21 is B1'. In this embodiment, the conductivity corresponding to the output signal of the compensation coil 12 does not change. Under the conditions that the excitation magnetic ring 1 and the induction magnetic ring 2 are the same and the temperature is the same, and considering that the conductivity of the liquid being measured and the conductivity of the liquid characterized by the compensation coil 12 are usually different, the effect of temperature change on the excitation magnetic ring 1 and the induction magnetic ring 2 has a linear relationship. Therefore, Furthermore, the formula for calculating the second amplitude error is as follows:

[0076]

[0077] Where ΔA represents the second amplitude error; A 初 This represents the second voltage amplitude; ΔB = B 测 -B 参 Indicates the first amplitude error; B 测 Indicates the first voltage amplitude; B 参 This indicates the reference voltage amplitude.

[0078] Further, voltage amplitude A 测 =A 初 +ΔA.

[0079] After that, A 测 As A x C is obtained by solving the above formula (1). x .

[0080] It should be noted that, considering the slow change in temperature, the compensation circuit 5 is used to correct the second voltage amplitude based on the second amplitude error when the second amplitude error is greater than or equal to a preset first threshold. Otherwise, no compensation is performed, and the second voltage amplitude is directly substituted into the above formula (1) to calculate the conductivity, which is the conductivity of the liquid to be tested. The first threshold can be determined in combination with the actual situation, and this embodiment does not impose a specific limitation on it. In addition, when the second amplitude error is greater than or equal to the preset first threshold, it can be considered that the influence of temperature change is relatively large, so compensation is required.

[0081] As a feasible implementation, the compensation circuit 5 is used to solve for conductivity based on the relationship between voltage amplitude and conductivity, to determine the first conductivity corresponding to the first voltage amplitude and the second conductivity corresponding to the second voltage amplitude; to determine the first conductivity error based on the first conductivity and the reference conductivity corresponding to the output signal of the compensation coil 12 at the reference temperature of the excitation magnetic ring 1; to determine the relationship between the second conductivity error and the first conductivity based on the relationship between the first conductivity error and the first conductivity to solve for the second conductivity error; and to correct the second conductivity based on the second conductivity error to determine the third conductivity of the liquid to be measured.

[0082] It should be noted that the reference conductivity can be understood as the conductivity corresponding to the voltage amplitude of the output signal of the compensation coil 12 after processing by the conditioning and extraction circuit 4 at the reference temperature. The first conductivity error reflects the effect of the change in reference temperature to the current temperature on the excitation magnetic ring 1, resulting in the change in the voltage amplitude of the output signal of the compensation coil 12. The second amplitude error reflects the effect of the change in reference temperature to the current temperature on the induction magnetic ring 2, resulting in the change in the voltage amplitude of the output signal of the induction coil 21.

[0083] In this embodiment, the excitation magnetic ring and the induction magnetic ring are the same, and the relationship between the first conductivity error and the first conductivity is equal to the relationship between the second conductivity error and the second conductivity.

[0084] In one example, the first voltage amplitude is taken as A. x The first conductivity is obtained by solving the above formula (1); the second voltage amplitude is used as A. x The second conductivity can be obtained by solving the above formula (1).

[0085] The calculation methods for amplitude error and conductivity error are similar. Just replace the voltage amplitude in formula (2) with conductivity to obtain the second conductivity error.

[0086] It should be noted that, considering the slow change in temperature, the compensation circuit 5 can correct the second conductivity based on the second conductivity error when the second conductivity error is greater than or equal to a preset second threshold, thereby determining the third conductivity of the liquid to be tested. The second threshold can be determined based on actual conditions, and this embodiment does not impose a specific limitation on it. Furthermore, when the second conductivity error is greater than or equal to the preset second threshold, the influence of temperature can be considered significant; therefore, compensation is necessary.

[0087] In addition, the compensation circuit 5 is also used to comprehensively consider the conductivity calculated after the second voltage amplitude correction and the result after the second conductivity correction, thereby ensuring the accuracy of the measurement results.

[0088] As a feasible implementation method, the compensation circuit 5 can be a microcontroller.

[0089] As a feasible implementation, the guide tube 3 is located between the excitation magnetic ring 1 and the induction magnetic ring 2, through which the liquid to be tested passes and discharges the liquid to be tested.

[0090] In one example, the guide tube 3 is a straight tube, for example, it can be a quartz tube.

[0091] As a feasible implementation, a shim 6 is provided between the excitation magnetic ring 1 and the induction magnetic ring 2. The shim 6 is used to separate the excitation magnetic ring 1 and the induction magnetic ring 2 to ensure normal operation.

[0092] like Figure 3 The diagram illustrates a conductivity measurement method provided in this embodiment. The method provided in this embodiment can be applied to the aforementioned conductivity sensor. In this embodiment, the method specifically includes the following steps:

[0093] Step 301: Apply an excitation signal to the excitation coil and obtain the self-inductance signal output by the compensation coil.

[0094] When the current in the excitation coil changes, the magnetic field of the excitation magnetic ring 1 changes due to the change in the current, thereby generating an induced electromotive force in the compensation coil, which in turn causes the compensation coil to output a self-induced signal.

[0095] The self-inductance signal is used to reflect the magnetic field condition of the excitation magnetic ring at the current temperature.

[0096] Step 302: When the guide tube passes through the liquid to be tested, acquire the induction signal output by the induction coil.

[0097] When the current in the excitation coil changes and the guide tube passes through the liquid to be measured, it is equivalent to connecting a liquid equivalent resistance Rc in series between the excitation magnetic ring and the induction magnetic ring. Therefore, an induced electromotive force will be generated in the induction coil, which will cause the induction coil to output an induced signal.

[0098] The induced signal is used to reflect the magnetic field condition of the induced magnetic ring at the current temperature.

[0099] Step 303: After conditioning the self-inductance signal and the induction signal respectively, extract the voltage amplitude to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induction signal.

[0100] Considering the different generation principles of self-inductance and induced signals—one being self-inductance and the other mutual inductance—different conditioning methods are required for them. Furthermore, considering the impact of temperature changes on the circuit, this embodiment performs the same voltage amplitude extraction process on both the conditioned self-inductance and induced signals to minimize this effect.

[0101] Step 304: Determine the first amplitude error based on the first voltage amplitude and the reference voltage amplitude of the excitation magnetic ring's compensation coil output signal at the reference temperature.

[0102] The first amplitude error indicates the effect of the change in reference temperature to the current temperature on the excitation magnetic ring, resulting in a change in the voltage amplitude of the compensation coil output signal.

[0103] In practical applications, at room temperature, the voltage amplitude of the compensation coil output signal after passing through the conditioning and extraction circuit 4 is used as the reference voltage amplitude.

[0104] Step 305: Based on the relationship between the first amplitude error and the first voltage amplitude, determine the relationship between the second amplitude error and the second voltage amplitude to solve for the second amplitude error.

[0105] The second amplitude error indicates the effect of the change in reference temperature to the current temperature on the induction magnetic ring, resulting in a change in the voltage amplitude of the output signal of the induction coil.

[0106] Step 306: Correct the second voltage amplitude based on the second amplitude error.

[0107] Step 307: Based on the corrected second voltage amplitude, the relationship between voltage amplitude and conductivity, solve for conductivity to determine the conductivity of the liquid to be tested.

[0108] As can be seen from the above technical solutions, the beneficial effects of this embodiment are:

[0109] The voltage amplitude corresponding to the induced signal generated by the induction coil is compensated by the change in voltage amplitude of the output signal of the compensation coil under temperature changes, thereby ensuring the measurement accuracy of the conductivity sensor.

[0110] like Figure 4 The diagram illustrates a conductivity measurement method provided in this embodiment. The method provided in this embodiment can be applied to the aforementioned conductivity sensor. Specifically, the method includes the following steps:

[0111] Step 401: Apply an excitation signal to the excitation coil and obtain the self-inductance signal output by the compensation coil.

[0112] For details, please refer to step 301, which will not be repeated here.

[0113] Step 402: When the guide tube passes through the liquid to be tested, acquire the induction signal output by the induction coil.

[0114] For details, please refer to step 302, which will not be repeated here.

[0115] Step 403: After conditioning the self-inductance signal and the induction signal respectively, extract the voltage amplitude to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induction signal.

[0116] For details, please refer to step 303, which will not be repeated here.

[0117] Step 404: Solve for the conductivity based on the relationship between voltage amplitude and conductivity, and determine the first conductivity corresponding to the first voltage amplitude and the second conductivity corresponding to the second voltage amplitude.

[0118] The relationship between voltage amplitude and conductivity is usually considered to be constant. Therefore, the first conductivity corresponding to the first voltage amplitude and the second conductivity corresponding to the second voltage amplitude can be determined by the above formula (1).

[0119] Step 405: Determine the first conductivity error based on the first conductivity and the reference conductivity corresponding to the output signal of the compensation coil at the reference temperature of the excitation magnetic ring.

[0120] In practical applications, at room temperature, the voltage amplitude of the output signal of the compensation coil after passing through the conditioning and extraction circuit 4 is substituted into the above formula (1), and the obtained conductivity is used as the reference conductivity.

[0121] The first amplitude error indicates the effect of the change in reference temperature to the current temperature on the excitation magnetic ring, resulting in the change in conductivity of the output signal of the compensation coil.

[0122] Step 406: Based on the relationship between the first conductivity error and the first conductivity, determine the relationship between the second conductivity error and the second conductivity to solve for the second conductivity error.

[0123] The second amplitude error indicates the effect of the change in reference temperature to the current temperature on the induction magnetic ring, resulting in the change in conductivity of the output signal of the induction coil.

[0124] Step 407: Correct the second conductivity based on the second conductivity error, and determine the third conductivity of the liquid to be tested.

[0125] As can be seen from the above technical solutions, the beneficial effects of this embodiment are:

[0126] The conductivity sensor compensates for the change in conductivity of the output signal of the compensation coil under temperature changes, thereby ensuring the measurement accuracy of the conductivity sensor.

[0127] Figure 5This is a schematic diagram of the structure of a conductivity sensor provided in this embodiment. At the hardware level, the sensor includes a processor 501 and a memory 502 storing execution instructions. Optionally, it also includes an internal bus 503 and a network interface 504. The memory 502 may include main memory 5021, such as high-speed random-access memory (RAM), or it may include non-volatile memory 5022, such as at least one disk storage device. The processor 501, network interface 504, and memory 502 can be interconnected via the internal bus 503. The internal bus 503 can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The internal bus 503 can be divided into an address bus, a data bus, a control bus, etc., for ease of representation. Figure 5 The symbol is represented by only one double-headed arrow, but this does not mean that there is only one bus or one type of bus. Of course, the electronic device may also include other hardware required for other services. When processor 501 executes the execution instructions stored in memory 502, processor 501 executes the method in any embodiment of the present invention, and is at least used to perform... Figure 3 or Figure 4 The method shown.

[0128] In one possible implementation, the processor reads the corresponding execution instructions from non-volatile memory into main memory and then executes them. Alternatively, it may obtain the corresponding execution instructions from other devices to form a conductivity measurement method at the logical level. The processor executes the execution instructions stored in the memory to implement the conductivity measurement method provided in any embodiment of the present invention through the executed instructions.

[0129] The processor may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above methods can be completed through integrated logic circuits in the processor's hardware or through software instructions. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in this embodiment. The general-purpose processor can be a microprocessor or any conventional processor.

[0130] This embodiment also provides a computer-readable storage medium including executable instructions. When the processor of an electronic device executes the executable instructions, the processor performs the method provided in any embodiment of the present invention. Specifically, the electronic device may be as follows: Figure 5 The electronic device shown; the execution instruction is a computer program corresponding to a conductivity measurement method.

[0131] Those skilled in the art will understand that embodiments of the present invention can be provided as methods or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or a combination of software and hardware.

[0132] The various embodiments in this invention are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0133] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A conductivity sensor, characterized in that, include: An excitation magnetic ring has an excitation coil and a compensation coil wound around its core. An excitation signal is applied to both ends of the excitation coil to cause the compensation coil to output a self-inductance signal. The self-inductance signal is used to reflect the magnetic field of the excitation magnetic ring at the current temperature. An induction magnetic ring has an induction coil wound around its magnetic core. A flow guide tube, disposed between the excitation magnetic ring and the induction magnetic ring, is used to allow the liquid to be measured to pass through, so that the induction coil outputs an induction signal; The conditioning and extraction circuit is used to condition the self-inductance signal and the induced signal respectively, and then extract the voltage amplitude to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induced signal; A compensation circuit is used to determine a first amplitude error based on the first voltage amplitude and the reference voltage amplitude of the compensation coil output signal of the excitation magnetic ring at a reference temperature; to determine a second amplitude error based on the relationship between the first amplitude error and the first voltage amplitude, and to solve for the second amplitude error based on the relationship between the first amplitude error and the first voltage amplitude; to correct the second voltage amplitude based on the second amplitude error and the voltage amplitude of the induced signal at the reference temperature; and to solve for the conductivity based on the corrected second voltage amplitude, the voltage amplitude, and the conductivity, thereby determining the conductivity of the liquid to be measured. Alternatively, a compensation circuit is used to solve for conductivity based on the relationship between voltage amplitude and conductivity, determining a first conductivity corresponding to the first voltage amplitude and a second conductivity corresponding to the second voltage amplitude; determining a first conductivity error based on the first conductivity and a reference conductivity corresponding to the output signal of the compensation coil of the excitation magnetic ring at a reference temperature; determining a second conductivity error based on the relationship between the first conductivity error and the first conductivity, and the relationship between the second conductivity error and the second conductivity to solve for the second conductivity error; correcting the second conductivity based on the second conductivity error and the conductivity of the induced signal at the reference temperature, and determining a third conductivity of the liquid to be tested. The conditioning and extraction circuit is used to extract the same voltage amplitude after subjecting the self-inductance signal and the inductance signal to different conditioning processes. The conditioning extraction circuit includes: A first conditioning circuit is used to perform first conditioning on the self-inductance signal to determine a first voltage signal; The second conditioning circuit is used to perform a second conditioning on the induced signal to determine a second voltage signal; A common circuit is used to perform the same voltage amplitude extraction process on the first voltage signal and the second voltage signal to determine the first voltage amplitude corresponding to the first voltage signal and the second voltage amplitude corresponding to the second voltage signal; The first conditioning step is voltage divider processing; The second conditioning step is voltage signal conversion processing; The compensation circuit is a microcontroller; The induction magnetic ring and the excitation magnetic ring are the same; The conductivity or voltage amplitude corresponding to the second induction signal generated by the induction coil is corrected by the first induction signal generated by the compensation coil.

2. The conductivity sensor according to claim 1, characterized in that, The shared circuit includes: A signal selection circuit is used to select one of the second voltage signal and the first voltage signal as an input signal; An amplifier circuit is used to amplify an input signal and determine the amplified voltage signal corresponding to the input signal; An amplitude extraction circuit is used to extract the amplitude of the amplified voltage signal and determine the analog voltage amplitude signal. A digital sampling circuit is used to convert the analog voltage amplitude signal into a voltage amplitude. Wherein, when the input signal is the first voltage signal, the voltage amplitude output by the digital sampling circuit is the first voltage amplitude; when the input signal is the second voltage signal, the voltage amplitude output by the digital sampling circuit is the second voltage amplitude.

3. The conductivity sensor according to claim 2, characterized in that, The compensation circuit is used to determine a first sampling frequency and a second sampling frequency; wherein the first sampling frequency is greater than the second sampling frequency. The signal selection circuit is used to select the first voltage signal as an input signal based on a first sampling frequency and to select the second voltage signal as an input signal based on a second sampling frequency.

4. The conductivity sensor according to claim 1, characterized in that, The compensation circuit is used to correct the second voltage amplitude based on the second amplitude error when the second amplitude error is greater than or equal to a preset first threshold; and to determine the conductivity of the liquid to be tested by solving the conductivity based on the corrected second voltage amplitude, the voltage amplitude, and the conductivity. The compensation circuit is used to correct the second conductivity based on the second conductivity error when the second conductivity error is greater than or equal to a preset second threshold, and to determine the third conductivity of the liquid to be tested; The relationship between the first amplitude error and the first voltage amplitude is the same as the relationship between the second amplitude error and the second voltage amplitude. The relationship between the first conductivity error and the first conductivity is the same as the relationship between the second conductivity error and the second conductivity.

5. A method for measuring electrical conductivity, characterized in that, An application is made in a conductivity sensor, the conductivity sensor comprising an excitation magnetic ring with an excitation coil and an induction coil sleeved on a magnetic core, an induction magnetic ring with an induction coil sleeved on a magnetic core, and a guide tube between the excitation magnetic ring and the induction magnetic ring, the method comprising: An excitation signal is applied to the excitation coil to obtain the self-inductance signal output by the compensation coil; As the guide tube passes through the liquid to be tested, the induced signal output by the induction coil is acquired; After conditioning the self-inductance signal and the induced signal respectively, voltage amplitude is extracted to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induced signal; Based on the first voltage amplitude and the reference voltage amplitude of the compensation coil output signal of the excitation magnetic ring at the reference temperature, the first amplitude error is determined; Based on the relationship between the first amplitude error and the first voltage amplitude, the relationship between the second amplitude error and the second voltage amplitude is determined to solve for the second amplitude error; The second voltage amplitude is corrected based on the second amplitude error and the voltage amplitude of the induced signal at the reference temperature; The conductivity is determined by solving the relationship between the corrected second voltage amplitude, voltage amplitude, and conductivity.

6. The conductivity measurement method according to claim 5, characterized in that, When the second amplitude error is greater than or equal to a preset first threshold, the second voltage amplitude is corrected based on the second amplitude error; the conductivity is solved based on the corrected second voltage amplitude, the voltage amplitude and the conductivity, and the conductivity of the liquid to be tested is determined.

7. A method for measuring electrical conductivity, characterized in that, An application is made in a conductivity sensor, the conductivity sensor comprising an excitation magnetic ring with an excitation coil and an induction coil sleeved on a magnetic core, an induction magnetic ring with an induction coil sleeved on a magnetic core, and a guide tube between the excitation magnetic ring and the induction magnetic ring, the method comprising: An excitation signal is applied to the excitation coil to obtain the self-inductance signal output by the compensation coil; As the guide tube passes through the liquid to be tested, the induced signal output by the induction coil is acquired; After conditioning the self-inductance signal and the induced signal respectively, voltage amplitude is extracted to determine the first voltage amplitude corresponding to the self-inductance signal and the second voltage amplitude corresponding to the induced signal; The conductivity is calculated based on the relationship between voltage amplitude and conductivity, thereby determining the first conductivity corresponding to the first voltage amplitude and the second conductivity corresponding to the second voltage amplitude. The first conductivity error is determined based on the first conductivity and the reference conductivity corresponding to the output signal of the compensation coil of the excitation magnetic ring at a reference temperature; Based on the relationship between the first conductivity error and the first conductivity, the relationship between the second conductivity error and the second conductivity is determined to solve for the second conductivity error; The third conductivity of the liquid to be tested is determined by correcting the second conductivity based on the second conductivity error and the conductivity of the induced signal at the reference temperature.

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