Conductivity sensor sensitivity improving circuit and parameter design method

Abstract

The invention discloses a conductivity sensor sensitivity improving circuit and a parameter design method, and the method comprises the steps: firstly, determining key structure parameters of a sensor, constructing an equivalent circuit model of the sensor, designing a capacitance compensation module, carrying out the wide-frequency-band impedance matching and frequency compensation of the induction type conductivity sensor, and carrying out the impedance matching and frequency compensation of the induction type conductivity sensor according to the equivalent circuit model; and deriving two key performance indexes of output sensitivity and linearity of the sensor. A comprehensive evaluation index is constructed to balance the relation between sensitivity and linearity. And carrying out optimization solution on the comprehensive evaluation index, and determining the optimal working frequency which can maximize the sensitivity of the sensor and minimize the linearity loss. The broadband impedance matching technology and the particle swarm optimization algorithm are combined, and the performance optimization design of the induction type conductivity sensor under different working frequencies is achieved. According to the optimal sensor design method, the linearity is ensured while the sensitivity is improved, so that the sensor can still work stably and accurately under complex working conditions.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a conductivity sensor sensitivity enhancement circuit and parameter design method. Background Art

[0002] As one of the five key sensors in the converter valve cooling system of the HVDC transmission system, the conductivity sensor is responsible for the precise monitoring of the conductivity of the cooling water. Its core function is to detect the ion concentration in the cooling water to ensure that the concentration does not exceed the set standard to prevent the formation of scale due to excessive ions. The formation of scale will seriously affect the heat dissipation efficiency of the converter valve, thus posing a potential threat to the operational stability of the entire system. At present, electrode-type conductivity sensors are still the main application form in the HVDC valve cooling system.

[0003] Electrode conductivity sensors calculate the conductivity of cooling water by applying voltage between two electrodes and measuring the current passing through. Since the magnitude of the current is directly proportional to the concentration of ions in the water, the measuring electrode must be in direct contact with the cooling water. However, this direct contact method inevitably causes the electrodes to gradually corrode over long-term use, which in turn affects the measurement accuracy of the sensor and shortens its service life. Especially in highly corrosive or high-temperature environments, the electrode deteriorates faster, resulting in increased maintenance costs for the sensor and the inability to continuously provide accurate conductivity measurement data.

[0004] To address the limitations of electrode sensors, inductive conductivity sensors have become an alternative. Inductive conductivity sensors work based on the principle of electromagnetic induction. They measure the change in induced voltage by generating an alternating magnetic field in an inductor coil to determine the conductivity of the cooling water. The induced voltage is linearly related to the conductivity of the cooling water, so there is no need for direct contact with the cooling water. The probes of this type of sensor are usually sealed with corrosion-resistant materials, which not only effectively prevents electrode corrosion problems, but also significantly improves the durability and long-term stability of the sensor.

[0005] However, the output signal of inductive conductivity sensors is much weaker than that of electrode sensors, mainly because electromagnetic induction signals are susceptible to attenuation and noise interference during transmission. Therefore, in order to ensure the measurement accuracy of inductive conductivity sensors, complex signal processing circuits are usually required. These circuits are complex in design and costly, which limits the widespread application of inductive sensors, especially in cost-sensitive industrial applications.

[0006] Based on this, the present invention proposes a conductivity sensor sensitivity enhancement circuit and parameter design method based on a broadband impedance matching network. By performing broadband impedance matching on the inductive conductivity sensor, the strength of the sensing signal can be significantly enhanced at different frequencies. This method not only improves the sensitivity of the sensor, but also improves its adaptability to various environmental conditions. This innovative design significantly expands the application range of the inductive conductivity sensor without increasing the manufacturing cost, and is particularly suitable for industrial environments and scientific research fields that require high precision and high reliability. Summary of the invention

[0007] The object of the present invention is to provide a conductivity sensor sensitivity enhancement circuit and parameter design method to solve the above problems existing in the prior art.

[0008] An embodiment of the present invention provides a method for designing parameters of a conductivity sensor sensitivity enhancement circuit, the method comprising:

[0009] Step S1: construct an equivalent circuit of the sensor according to the structural parameters of the inductive conductivity sensor, and calculate the equivalent impedance of the sensor; wherein the calculation formula of the equivalent circuit parameters of the sensor is:

[0010]

[0011] Z s =R m +jωL m (4)

[0012]

[0013] Where L is the inductance of the inductive conductivity sensor coil, R is the coil resistance, M 12 is the mutual inductance between the primary coil and water, M 34 is the mutual inductance between water and the secondary coil, μ0 is the magnetic permeability of vacuum, μ r is the magnetic permeability of the sensor magnetic ring, N is the number of turns of the magnetic core coil, h is the thickness of the magnetic core, r1 is the inner diameter of the magnetic core, r2 is the outer diameter of the magnetic core, ρ is the resistivity of the coil, l is the length of the coil, S is the cross-sectional area of ​​the coil; L1 is the inductance of the primary coil, L2 and L3 are the equivalent inductance of water, and L4 is the inductance of the secondary coil; Z s is the equivalent impedance, R m is the circuit equivalent resistance, L m is the circuit equivalent inductance, R s is the equivalent resistance of water; ω is the angular frequency;

[0014] Step S2: Calculate the compensation capacitance in the broadband impedance matching network according to the equivalent impedance of the sensor and the compensation frequency range. The compensation capacitance value includes the series matching capacitance Cs and the parallel matching capacitance Cp. The calculation formula of the compensation capacitance of the broadband impedance matching network is:

[0015] ω=2πf (7)

[0016]

[0017] Among them, C s is the series matching capacitor, C p is a parallel matching capacitor, f is a broadband compensation value; f is between f1 and f2, f1 is the lower limit of the broadband compensation range, and f2 is the upper limit of the broadband compensation range;

[0018] Step S3: using the sensitivity and linearity of the inductive conductivity sensor as evaluation indicators, comprehensively evaluating the output performance of the inductive conductivity sensor after adding the impedance matching network for broadband compensation according to the evaluation indicators; wherein the calculation method of the sensitivity and linearity of the sensor is defined as:

[0019]

[0020] Where, Sens is the sensitivity of the sensor, Line is the linearity of the sensor, Cond1 is the lower limit of the conductivity sensor measurement range, Cond2 is the upper limit of the sensor measurement range, U out (Cond2) is the output response function of the sensor with input Cond2, U out (Cond1) is the output response function of the sensor with input Cond1; ΔY max is the maximum deviation between the sensor calibration curve and the fitted straight line, Y is the full-scale output of the sensor; Sens and Line are functions of the operating frequency of the conductivity sensor;

[0021] Step S4: Comprehensively consider the linearity and sensitivity of the sensor, weight the two indicators, and obtain a performance evaluation function with the best overall performance; the performance evaluation function is:

[0022]

[0023] in, is the overall evaluation index, α1 is the weight of the conductivity sensor sensitivity, and α2 is the weight of the conductivity sensor linearity. The linearity and sensitivity of the sensor output are normalized. and They are the sensitivity and linearity after normalization, respectively;

[0024] Step S5: Optimize the weight of the overall performance evaluation function and the sensor operating frequency through the particle swarm algorithm. The weight and operating frequency of the overall performance evaluation function optimized by the particle swarm algorithm are:

[0025]

[0026] in, is the velocity of the particle swarm at time t+1; is the velocity of the particle swarm at the tth moment; w PSO is a non-negative inertia factor; To adjust the parameters of the local optimum; is a random number in the range [0,1]; is the local optimal position of the particle swarm at the tth moment; is the position of the particle swarm at the tth moment; To adjust the parameters of the global optimal value; is a random number in the range [0,1]; is the global optimal position of the particle swarm at the tth moment; is the position at time t+1.

[0027] Optionally, the method further includes:

[0028] If the overall performance evaluation function does not obtain the optimal value, step S5 is repeated; if the overall performance evaluation function obtains the optimal value, the optimal operating frequency of the sensor is obtained under comprehensive consideration of the sensor sensitivity improvement and linearity loss.

[0029] The embodiment of the present invention further provides a method for designing parameters of a conductivity sensor sensitivity enhancement circuit, the method comprising:

[0030] Determine the key structural parameters of the sensor, including the number of coil windings and the size of the magnetic core;

[0031] Construct a capacitance compensation module to perform frequency compensation on the conductivity characteristics of the sensor and derive the sensitivity and linearity indicators of the sensor;

[0032] Generate weighted comprehensive evaluation indicators of sensitivity and linearity as a basis for evaluating the overall performance of the sensor;

[0033] The particle swarm optimization algorithm is used to optimize the evaluation index to find the parameter combination with the best performance;

[0034] By judging whether the optimal state is reached, the optimal sensitivity, linearity and operating frequency of the sensor are finally determined.

[0035] The embodiment of the present invention further provides a conductivity sensor sensitivity enhancement circuit, which is applied to the parameter design method of the above-mentioned conductivity sensor sensitivity enhancement circuit; the conductivity sensor sensitivity enhancement circuit includes the resistance of the primary coil winding, the resistance of the secondary coil, the equivalent resistance of the cooling water, the self-inductance of the primary coil, and the self-inductance of the secondary coil; wherein,

[0036] The cooling water is equivalent to a turn of coil wound on the magnetic core, that is, equivalent to the inductance L2 on the primary magnetic core and the inductance L3 on the secondary magnetic core; there are mutual inductances M12 and M34 between the primary coil and the cooling water, and between the cooling water and the secondary coil.

[0037] Optionally, the conductivity sensor sensitivity circuit based on broadband impedance matching further includes an impedance matching network;

[0038] The impedance matching network includes a series capacitor and a parallel capacitor; the compensation network is arranged between the excitation source and the primary coil to perform broadband impedance matching on the entire sensor.

[0039] Compared with the prior art, the embodiments of the present invention achieve the following beneficial effects:

[0040] The embodiment of the present invention also provides a conductivity sensor sensitivity enhancement circuit and parameter design method, which is mainly used in the conductivity monitoring of cooling water in a high-voltage DC valve cooling system. The method first constructs an equivalent circuit model of the sensor by determining the key structural parameters of the sensor (such as the number of coil windings, winding resistivity, magnetic core permeability, magnetic core size, etc.). On this basis, a capacitance compensation module is designed to perform impedance matching and frequency compensation for the inductive conductivity sensor in a wide frequency band, thereby significantly enhancing the sensitivity of the sensor. Then, according to the equivalent circuit model, two key performance indicators of the sensor's output sensitivity (Sens) and linearity (Line) are derived. In order to optimize these indicators, a comprehensive evaluation index is constructed as a function of the sensor's operating frequency to weigh the relationship between sensitivity and linearity. Then, by introducing a particle swarm optimization algorithm (PSO), the comprehensive evaluation index is optimized and solved to determine the optimal operating frequency that can maximize the sensor sensitivity and minimize the linearity loss. Combining broadband impedance matching technology with the particle swarm optimization algorithm, the performance optimization design of the inductive conductivity sensor at different operating frequencies is realized. Without significantly increasing the manufacturing cost, the sensitivity of the sensor is significantly improved, and its application range is expanded, especially in industrial environments and scientific research where high precision and high reliability are required. The present invention ultimately obtains the optimal sensor design method that improves sensitivity while ensuring linearity, so that the sensor can still work stably and accurately under complex working conditions.

[0041] (1) The embodiment of the present invention proposes that an impedance matching network is added to the inductive conductivity sensor to perform broadband compensation, which can offset the reactive power of the sensor, thereby increasing the output of the sensor and improving the sensitivity of the sensor;

[0042] (2) The embodiment of the present invention provides a parameter design method for a broadband compensation network. The method comprehensively considers the linearity and sensitivity of the sensor, so that the loss of linearity is minimized while improving the sensitivity of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a parameter design method for a conductivity sensor sensitivity enhancement circuit provided by an embodiment of the present invention.

[0044] Figure 2 FIG. 4 is an equivalent circuit diagram of the inductive conductivity sensor of the present invention.

[0045] Figure 3 A circuit diagram of a broadband compensation network designed for the present invention. DETAILED DESCRIPTION

[0046] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0047] In view of the defects or improvement needs of the prior art, an embodiment of the present invention provides a conductivity sensor sensitivity improvement circuit and parameter design method based on a broadband impedance matching network, the purpose of which is to add an impedance matching network to the inductive conductivity sensor to perform broadband compensation to offset the reactive power of the sensor, thereby increasing the output of the sensor and improving the sensitivity of the sensor. However, the broadband compensation method will affect the linearity of the sensor, so a parameter design method of the broadband compensation network is proposed at the same time. The method comprehensively considers the linearity and sensitivity of the sensor, so that while improving the sensitivity of the sensor, the loss of linearity is minimized. The conductivity sensor sensitivity improvement circuit and parameter design method of the broadband impedance matching network provided by the embodiment of the present invention (parameter design method of conductivity sensor sensitivity improvement circuit) are suitable for the field of cooling water measurement of flow valve cooling system, and can significantly improve the sensitivity of the inductive conductivity sensor. Please refer to the following embodiments for details.

[0048] Example 1

[0049] like Figure 1 As shown, an embodiment of the present invention provides a parameter design method for a conductivity sensor sensitivity improvement circuit, the method comprising:

[0050] Step S1: construct an equivalent circuit of the sensor according to the structural parameters of the inductive conductivity sensor, and calculate the equivalent impedance of the sensor; wherein the calculation formula of the equivalent circuit parameters of the sensor is:

[0051]

[0052] Z s =R m +jωL m (4)

[0053]

[0054] Where L is the inductance of the inductive conductivity sensor coil, R is the coil resistance, M 12 is the mutual inductance between the primary coil and water, M 34 is the mutual inductance between water and the secondary coil, μ0 is the magnetic permeability of vacuum, μ r is the magnetic permeability of the sensor magnetic ring, N is the number of turns of the magnetic core coil, h is the thickness of the magnetic core, r1 is the inner diameter of the magnetic core, r2 is the outer diameter of the magnetic core, ρ is the resistivity of the coil, l is the length of the coil, S is the cross-sectional area of ​​the coil; L1 is the inductance of the primary coil, L2 and L3 are the equivalent inductance of water, and L4 is the inductance of the secondary coil; Z s is the equivalent impedance, R m is the circuit equivalent resistance, L m is the circuit equivalent inductance, R s is the equivalent resistance of water; ω is the angular frequency;

[0055] Step S2: Calculate the compensation capacitance in the broadband impedance matching network according to the equivalent impedance of the sensor and the compensation frequency range. The compensation capacitance value includes the series matching capacitance Cs and the parallel matching capacitance Cp. The calculation formula of the compensation capacitance of the broadband impedance matching network is:

[0056] ω=2πf (7)

[0057]

[0058] Among them, C s is the series matching capacitor, C p is a parallel matching capacitor, and f is a broadband compensation value; the value of f is between f1 and f2, where f1 is the lower limit of the broadband compensation range and f2 is the upper limit of the broadband compensation range;

[0059] Step S3: using the sensitivity and linearity of the inductive conductivity sensor as evaluation indicators, comprehensively evaluating the output performance of the inductive conductivity sensor after adding the impedance matching network for broadband compensation according to the evaluation indicators; wherein the calculation method of the sensitivity and linearity of the sensor is defined as:

[0060]

[0061] Where, Sens is the sensitivity of the sensor, Line is the linearity of the sensor, Cond1 is the lower limit of the conductivity sensor measurement range, Cond2 is the upper limit of the sensor measurement range, U out (Cond2) is the output response function of the sensor with input Cond2, U out (Cond1) is the output response function of the sensor with input Cond1; ΔY max is the maximum deviation between the sensor calibration curve and the fitted straight line, Y is the full-scale output of the sensor; Sens and Line are functions of the operating frequency of the conductivity sensor;

[0062] Step S4: Comprehensively consider the linearity and sensitivity of the sensor, weight the two indicators, and obtain a performance evaluation function with the best overall performance; the performance evaluation function is:

[0063]

[0064] in, is the overall evaluation index, α1 is the weight of the conductivity sensor sensitivity, and α2 is the weight of the conductivity sensor linearity. The linearity and sensitivity of the sensor output are normalized. and They are the sensitivity and linearity after normalization, respectively;

[0065] Step S5: Optimize the weight of the overall performance evaluation function and the sensor operating frequency through the particle swarm algorithm. The weight and operating frequency of the overall performance evaluation function optimized by the particle swarm algorithm are:

[0066]

[0067] in, is the velocity of the particle swarm at time t+1; is the velocity of the particle swarm at the tth moment; w PSO is a non-negative inertia factor; To adjust the parameters of the local optimum; is a random number in the range [0,1]; is the local optimal position of the particle swarm at the tth moment; is the position of the particle swarm at the tth moment; To adjust the parameters of the global optimal value; is a random number in the range [0,1]; is the global optimal position of the particle swarm at the tth moment; is the position at time t+1.

[0068] As a further feature, the method further comprises:

[0069] If the overall performance evaluation function does not obtain the optimal value, step S5 is repeated; if the overall performance evaluation function obtains the optimal value, the optimal operating frequency of the sensor is obtained under comprehensive consideration of the sensor sensitivity improvement and linearity loss.

[0070] The specific process of the parameter design method of the conductivity sensor sensitivity enhancement circuit provided in the embodiment of the present invention may also be: determining the key structural parameters of the sensor, including the number of coil windings and the size of the magnetic core. Constructing a capacitance compensation module, performing frequency compensation on the conductivity characteristics of the sensor, and deriving the sensitivity and linearity indicators of the sensor.

[0071] Generate a weighted comprehensive evaluation index of sensitivity and linearity as the basis for evaluating the overall performance of the sensor. Apply the particle swarm optimization algorithm to optimize and solve the evaluation index to find the parameter combination with the best performance. By judging whether the optimal state is achieved, the optimal sensitivity, linearity and operating frequency of the sensor are finally determined. Figure 1 As shown in the figure, first, the key structural parameters of the sensor are determined, including the number of coil windings, the size of the magnetic core, etc.; secondly, a capacitance compensation module is constructed to perform frequency compensation on the conductivity characteristics of the sensor, and the sensitivity (Sens) and linearity (Line) indicators of the sensor are derived; then, a weighted comprehensive evaluation index of sensitivity and linearity is generated as a basis for evaluating the overall performance of the sensor; then, the particle swarm optimization algorithm (PSO) is applied to optimize and solve the evaluation index to find the parameter combination with the best performance; finally, by judging whether the optimal state is reached, the optimal sensitivity, linearity and operating frequency of the sensor are finally determined to ensure that it achieves the best performance in practical applications.

[0072] Based on the above-mentioned parameter design method of the conductivity sensor sensitivity improvement circuit, a conductivity sensor sensitivity improvement circuit is designed. Figure 2 As shown, the conductivity sensor sensitivity enhancement circuit includes the resistance of the primary coil winding, the resistance of the secondary coil, the equivalent resistance of the cooling water, the self-inductance of the primary coil, and the self-inductance of the secondary coil; wherein the cooling water is equivalent to a turn of coil wound on the magnetic core, that is, equivalent to the inductance L2 on the primary magnetic core and the inductance L3 on the secondary magnetic core; there is a mutual inductance M between the primary coil and the cooling water, and between the cooling water and the secondary coil 12 、M 34 Please refer to Figure 2 In the equivalent circuit of the inductive conductivity sensor, R1 is the resistance of the primary coil winding, R2 is the resistance of the secondary coil, and R sis the equivalent resistance of the cooling water, L1 is the self-inductance of the primary coil, and L2 is the self-inductance of the secondary coil. Here, the cooling water is equivalent to a coil wound on the magnetic core, so the cooling water also has an equivalent self-inductance, that is, L2 on the primary magnetic core and L3 on the secondary magnetic core. At the same time, there is a mutual inductance M between the primary coil and the cooling water, and between the cooling water and the secondary coil. 12 、M 34 . Since there is usually a shield between the primary coil and the secondary coil, the mutual inductance between the primary coil and the secondary coil can be ignored. At the same time, since the leakage inductance is very small, it is also ignored here. U1 is the sinusoidal excitation voltage, which generates an alternating magnetic field in the cooling water through the primary coil. U2 is the output induced voltage. Before compensation, the induced voltage is linearly related to the conductivity of the cooling water. The conductivity of the cooling water is determined by measuring the change in the induced voltage.

[0073] As a further feature, the conductivity sensor sensitivity enhancement circuit further includes an impedance matching network; the impedance matching network includes a series capacitor and a parallel capacitor; and a compensation network is arranged between the excitation source and the primary coil to perform broadband impedance matching on the entire sensor. Figure 3 As shown, in the impedance matching network, C s For series capacitance, since C s The capacitance value needs to be calculated through the collective formula, which can be obtained through C s 1. C s 2 A series of different capacitors are connected in parallel to obtain a series capacitor with a specific capacitance; C p For parallel capacitors, like series capacitors, C p Can be done through C p 1. C p 2, etc. A series of different capacitors are connected in parallel to finally obtain a parallel capacitor with a specific capacitance. The compensation network is set between the excitation source and the primary coil to perform broadband impedance matching for the entire sensor.

[0074] In summary, the embodiments of the present invention achieve the following beneficial effects:

[0075] (1) The proposed method of adding an impedance matching network to the inductive conductivity sensor for broadband compensation can offset the reactive power of the sensor, thereby increasing the output of the sensor and improving the sensitivity of the sensor;

[0076] (2) A parameter design method for a broadband compensation network is proposed. This method comprehensively considers the linearity and sensitivity of the sensor, thereby minimizing the loss of linearity while improving the sensitivity of the sensor.

Claims

1. A method for designing parameters of a conductivity sensor sensitivity enhancement circuit, characterized in that: The method comprises: Step S1: construct an equivalent circuit of the sensor according to the structural parameters of the inductive conductivity sensor, and calculate the equivalent impedance of the sensor; wherein the calculation formula of the equivalent circuit parameters of the sensor is: Z s =R m +jωL m (4) Where L is the inductance of the inductive conductivity sensor coil, R is the coil resistance, M 12 is the mutual inductance between the primary coil and water, M 34 is the mutual inductance between water and the secondary coil, μ0 is the magnetic permeability of vacuum, μ r is the magnetic permeability of the sensor magnetic ring, N is the number of turns of the magnetic core coil, h is the thickness of the magnetic core, r1 is the inner diameter of the magnetic core, r2 is the outer diameter of the magnetic core, ρ is the resistivity of the coil, l is the length of the coil, S is the cross-sectional area of ​​the coil; L1 is the inductance of the primary coil, L2 and L3 are the equivalent inductance of water, and L4 is the inductance of the secondary coil; Z s is the equivalent impedance, R m is the circuit equivalent resistance, L m is the circuit equivalent inductance, R s is the equivalent resistance of water; ω is the angular frequency; Step S2: Calculate the compensation capacitance in the broadband impedance matching network according to the equivalent impedance of the sensor and the compensation frequency range. The compensation capacitance value includes the series matching capacitance Cs and the parallel matching capacitance Cp. The calculation formula of the compensation capacitance of the broadband impedance matching network is: ω=2πf (7) Among them, C s is the series matching capacitor, C p is a parallel matching capacitor, and f is a broadband compensation value; the value of f is between f1 and f2, where f1 is the lower limit of the broadband compensation range and f2 is the upper limit of the broadband compensation range; Step S3: using the sensitivity and linearity of the inductive conductivity sensor as evaluation indicators, comprehensively evaluating the output performance of the inductive conductivity sensor after adding the impedance matching network for broadband compensation according to the evaluation indicators; wherein the calculation method of the sensitivity and linearity of the sensor is defined as: Where, Sens is the sensitivity of the sensor, Line is the linearity of the sensor, Cond1 is the lower limit of the conductivity sensor measurement range, Cond2 is the upper limit of the sensor measurement range, U out (Cond2) is the output response function of the sensor with input Cond2, U out (Cond1) is the output response function of the sensor with input Cond1; ΔY max is the maximum deviation between the sensor calibration curve and the fitted straight line, Y is the full-scale output of the sensor; Sens and Line are functions of the operating frequency of the conductivity sensor; Step S4: Comprehensively consider the linearity and sensitivity of the sensor, weight the two indicators, and obtain a performance evaluation function with the best overall performance; the performance evaluation function is: in, is the overall evaluation index, α1 is the weight of the conductivity sensor sensitivity, and α2 is the weight of the conductivity sensor linearity. The linearity and sensitivity of the sensor output are normalized. and They are the sensitivity and linearity after normalization, respectively; Step S5: The weight of the overall performance evaluation function and the sensor operating frequency are optimized by the particle swarm algorithm. The weight of the overall performance evaluation function and the operating frequency optimized by the particle swarm algorithm are: in, is the velocity of the particle swarm at time t+1; is the velocity of the particle swarm at the tth moment; w PSO is a non-negative inertia factor; To adjust the parameters of the local optimum; is a random number in the range [0, 1]; is the local optimal position of the particle swarm at the tth moment; is the position of the particle swarm at the tth moment; To adjust the parameters of the global optimal value; is a random number in the range [0, 1]; is the global optimal position of the particle swarm at the tth moment; is the position at time t+1.

2. The method for designing parameters of a conductivity sensor sensitivity enhancement circuit according to claim 1, characterized in that: The method further comprises: If the overall performance evaluation function does not obtain the optimal value, step S5 is repeated; if the overall performance evaluation function obtains the optimal value, the optimal operating frequency of the sensor is obtained under comprehensive consideration of the sensor sensitivity improvement and linearity loss.

3. A method for designing parameters of a conductivity sensor sensitivity enhancement circuit, characterized in that: The method comprises: Determine the key structural parameters of the sensor, including the number of coil windings and the size of the magnetic core; Construct a capacitance compensation module to perform frequency compensation on the conductivity characteristics of the sensor and derive the sensitivity and linearity indicators of the sensor; Generate weighted comprehensive evaluation indicators of sensitivity and linearity as a basis for evaluating the overall performance of the sensor; The particle swarm optimization algorithm is used to optimize the evaluation index to find the parameter combination with the best performance; By judging whether the optimal state is reached, the optimal sensitivity, linearity and operating frequency of the sensor are finally determined.

4. A conductivity sensor sensitivity enhancement circuit, characterized in that: The parameter design method of the conductivity sensor sensitivity enhancement circuit applied to claim 1; the conductivity sensor sensitivity enhancement circuit includes the resistance of the primary coil winding, the resistance of the secondary coil, the equivalent resistance of the cooling water, the self-inductance of the primary coil, and the self-inductance of the secondary coil; wherein, The cooling water is equivalent to a turn of coil wound on the magnetic core, which is equivalent to the inductance L2 on the primary magnetic core and the inductance L3 on the secondary magnetic core; there are mutual inductances M12 and M34 between the primary coil and the cooling water, and between the cooling water and the secondary coil.

5. The conductivity sensor sensitivity enhancement circuit according to claim 4, characterized in that: The conductivity sensor sensitivity enhancement circuit also includes an impedance matching network; The impedance matching network includes a series capacitor and a parallel capacitor; the compensation network is arranged between the excitation source and the primary coil to perform broadband impedance matching on the entire sensor.

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