Metering system and method for electromagnetic water meter polarization voltage processing

Abstract

The invention discloses a metering system for electromagnetic water meter polarization voltage processing. The metering system comprises an electrode input module, a differential amplification module, a first polarization processing module, a second polarization processing module, a reference voltage accumulation and amplification module and an ADC sampling module. The electrode input module, the differential amplification module, the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module are electrically connected in sequence, and the output end of the ADC sampling module is electrically connected with the input end of the second polarization processing module. The output end of the second polarization processing module is electrically connected with the input end of the first polarization processing module, the input end of the reference voltage accumulation and amplification module and the input end of the ADC sampling module. The invention further discloses a metering method for electromagnetic water meter polarization voltage processing. The technical problems that in the metering process of an existing electromagnetic water meter, due to polarization voltage interference, an AD value overflows, and the flow metering accuracy is poor are solved.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic water meters, and in particular to a metering system and method for polarization voltage processing of electromagnetic water meters. Background Art

[0002] Electrode polarization refers to the directional movement of positive and negative ions in the electrolyte fluid, forming a certain electric field in the electrode and the fluid, thereby generating a polarization voltage. If the two electrodes are exactly the same, then their polarization voltages should also be equal. In fact, because the material and surface treatment process of the electrodes are not exactly the same, different polarization voltages will inevitably be generated, resulting in interference signals directly entering the preamplifier with a high common mode rejection ratio. The amplified interference signal is superimposed on the normal signal, causing measurement errors. At present, the industry has adopted some hardware depolarization circuits, but this problem cannot be completely solved, especially for the fluctuating polarization voltage, there is no good way to deal with it. The patent document with application number 202410950670.3 discloses a water meter monitoring system and a monitoring method for household intelligent water use, which relates to the field of household water use, including a monitoring and acquisition module, a data collection control module and an application module; the system forms an electrode pair through an electrode B and an electrode A of unit length, and multiple electrode pairs are arranged on both sides of the water pipe in sequence. When a leak occurs at a certain position of the water pipe, the leak will change the humidity of the concrete around the position, thereby causing the impedance between the electrode B and the electrode A to change. The data collection control module controls the application of DC excitation between the electrode pairs and performs sampling. The application module integrates the judgment results of all electrode pairs based on the principle that the leakage points are usually adjacent and cannot appear in large numbers, thereby determining that the data change of a certain electrode pair is indeed caused by a water pipe leak, and at the same time associates the corresponding water pipe position, performs an alarm reminder, plays a role in real-time monitoring, and promptly alarms at the early stage of the leak, thereby reducing the loss caused by the leak to the family. Therefore, it is urgent to propose a metering system and method for polarization voltage processing of electromagnetic water meters to solve the technical problems of AD value overflow and poor flow metering accuracy caused by polarization voltage interference in the existing electromagnetic water meter metering process. Summary of the invention

[0003] The main purpose of the present invention is to propose a metering system and method for electromagnetic water meter polarization voltage processing, aiming to solve the technical problems of AD value overflow and poor flow measurement accuracy caused by polarization voltage interference in the existing electromagnetic water meter measurement process.

[0004] To achieve the above-mentioned purpose, the present invention provides a metering system for polarization voltage processing of an electromagnetic water meter, wherein the metering system for polarization voltage processing of an electromagnetic water meter comprises: an electrode input module, a differential amplification module, a first polarization processing module, a second polarization processing module, a reference voltage accumulation and amplification module and an ADC sampling module; the electrode input module, the differential amplification module, the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module are electrically connected in sequence, the output end of the ADC sampling module is electrically connected to the input end of the second polarization processing module, and the output end of the second polarization processing module is electrically connected to the input ends of the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module respectively.

[0005] One of the preferred schemes, the electrode input module is used to detect the electrode signal and collect the induced voltage of the excitation coil; the electrode input module includes a socket XS1, a first passive filtering circuit, a second passive filtering circuit and a capacitor C2; the socket is respectively connected to the electrode, the first passive filtering circuit, the second passive filtering circuit and the ground, the first passive filtering circuit is respectively connected to the capacitor C2, the differential amplifier module and the ground, and the other end of the capacitor C2 is respectively connected to the second passive filtering circuit, the differential amplifier module and the ground.

[0006] In one of the preferred solutions, the first passive filtering circuit includes a resistor R1 and a capacitor C1; one end of the resistor R1 is connected to pin 1 of the socket XS1, and the other end of the resistor R1 is respectively connected to the capacitor C1, the capacitor C2 and the differential amplifier module.

[0007] In one of the preferred solutions, the second passive filtering circuit includes a resistor R2 and a capacitor C3; one end of the resistor R2 is connected to pin 3 of the socket XS1, and the other end of the resistor R1 is respectively connected to the capacitor C3, the capacitor C2 and the differential amplifier module.

[0008] In one of the preferred schemes, the first polarization processing module is used to filter out the polarization voltage of the induced voltage; the first polarization processing module includes a low-pass filter and an amplifier; the low-pass filter is respectively connected to the differential amplification module, the amplifier and the second polarization processing module, and the amplifier is connected to the differential amplification module.

[0009] In one of the preferred schemes, the second polarization processing module includes a subtractor unit, a reference voltage input unit, a DAC feedback adjustment unit and a main control unit; the main control unit is electrically connected to the ADC sampling module and the DAC feedback adjustment unit, respectively, the DAC feedback adjustment unit is electrically connected to the subtractor unit, the subtractor unit is electrically connected to the first polarization processing module, and the reference voltage input unit is electrically connected to the subtractor unit, the reference voltage accumulation and amplification module and the ADC sampling module, respectively.

[0010] One of the preferred schemes, the reference voltage accumulation and amplification module includes an amplifier U7, a capacitor R9, a resistor R10, a resistor R11, a capacitor C19, a capacitor C20, a resistor R12 and a third passive filtering circuit; Pin 1 of the amplifier U7 is connected to the third passive filtering circuit, and the third passive filtering circuit is respectively connected to the second polarization processing module and the ADC sampling module, Pin 2 of the amplifier U7 is respectively connected to the power supply end and the capacitor C20, Pin 3 of the amplifier U7 is respectively connected to the resistor R9 and the resistor R10, and the other end of the resistor R10 is connected to the second polarization processing module, Pin 4 of the amplifier U7 is connected to the resistor R11, and the other end of the resistor R11 is connected to the first polarization processing module, Pin 5 of the amplifier U7 is respectively connected to the power supply end and the capacitor C19, and the other ends of the capacitor C19, the capacitor C20 and the resistor R9 are grounded.

[0011] In one of the preferred solutions, the ADC sampling module is a 24-bit ADC sampling module.

[0012] A metering method including a metering system for polarization voltage processing of an electromagnetic water meter, comprising the following steps:

[0013] S1. The main control unit is periodically excited, and the electrode input module collects the induced voltage of the excitation coil and amplifies it through the differential amplifier module;

[0014] S2, the first polarization processing module performs a polarization process on the collected induced voltage;

[0015] S3, the second polarization processing module performs secondary polarization processing on the induced voltage after the primary polarization processing;

[0016] S4, the reference voltage accumulation and amplification module amplifies the induced voltage after the secondary polarization processing, and simultaneously adds a reference voltage, and the ADC sampling module performs ADC conversion;

[0017] S5. Obtain multiple groups of AD values ​​of induced voltages, establish a comparative relationship between the AD value of the electromagnetic water meter and the flow velocity, calculate the flow signal of the electromagnetic water meter according to the caliber and flow velocity of the electromagnetic water meter, and return to step S1.

[0018] In one preferred solution, step S3 is specifically as follows:

[0019] The main control unit turns off the excitation and obtains the polarization voltage of the electrode in the non-excitation state;

[0020] The polarization voltage is amplified by the differential amplifier module, and the polarization voltage above the excitation cycle frequency is eliminated by the first polarization processing module, and then accumulated and amplified by the reference voltage accumulation and amplification module, and ADC conversion is performed by the ADC sampling module to obtain multiple groups of AD values, and the average value of the multiple groups of AD values ​​is calculated;

[0021] The DAC feedback adjustment unit converts the polarization voltage collected by the ADC sampling module into an analog voltage, and reversely subtracts the analog voltage from the subtractor unit to obtain a first signal.

[0022] In the above technical solution of the present invention, the metering system of the polarization voltage processing of the electromagnetic water meter includes: an electrode input module, a differential amplification module, a first polarization processing module, a second polarization processing module, a reference voltage accumulation and amplification module and an ADC sampling module; the electrode input module, the differential amplification module, the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module are electrically connected in sequence, the output end of the ADC sampling module is electrically connected to the input end of the second polarization processing module, and the output end of the second polarization processing module is electrically connected to the input end of the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module respectively. The present invention avoids ADC overflow and improves the accuracy of flow by eliminating the polarization voltage in the induced voltage, and solves the technical problems of AD value overflow and poor flow measurement accuracy caused by polarization voltage interference in the existing electromagnetic water meter measurement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0024] Figure 1 A first schematic diagram of a metering system for polarization voltage processing of an electromagnetic water meter according to an embodiment of the present invention;

[0025] Figure 2 A second schematic diagram of a metering system for polarization voltage processing of an electromagnetic water meter according to an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of a reference voltage accumulation and amplification module according to an embodiment of the present invention;

[0027] Figure 4 Schematic diagram of an ADC sampling module according to an embodiment of the present invention;

[0028] Figure 5A schematic diagram of a metering method for polarization voltage processing of an electromagnetic water meter according to an embodiment of the present invention.

[0029] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0032] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] See also Figure 1-Figure 4 According to one aspect of the present invention, the present invention provides a metering system for polarization voltage processing of an electromagnetic water meter, wherein the metering system for polarization voltage processing of an electromagnetic water meter comprises: an electrode input module, a differential amplification module, a first polarization processing module, a second polarization processing module, a reference voltage accumulation and amplification module and an ADC sampling module; the electrode input module, the differential amplification module, the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module are electrically connected in sequence, the output end of the ADC sampling module is electrically connected to the input end of the second polarization processing module, and the output end of the second polarization processing module is electrically connected to the input ends of the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module respectively.

[0034] Specifically, in this embodiment, the electrode input module is used to detect the electrode signal and collect the induced voltage of the excitation coil; the electrode input module includes a socket XS1, a first passive filtering circuit, a second passive filtering circuit and a capacitor C2; the socket is respectively connected to two electrodes, a first passive filtering circuit, a second passive filtering circuit and a ground terminal, the first passive filtering circuit is respectively connected to the capacitor C2, a differential amplifier module and a ground terminal, and the other end of the capacitor C2 is respectively connected to the second passive filtering circuit, the differential amplifier module and the ground terminal; the high-frequency signal of the induced voltage is filtered out by the first passive filtering circuit, the second passive filtering circuit and the capacitor C2.

[0035] Specifically, in this embodiment, the first passive filtering circuit includes a resistor R1 and a capacitor C1; one end of the resistor R1 is connected to pin 1 of the socket XS1, and the other end of the resistor R1 is respectively connected to the capacitor C1, the capacitor C2 and the differential amplifier module.

[0036] Specifically, in this embodiment, the second passive filtering circuit includes a resistor R2 and a capacitor C3; one end of the resistor R2 is connected to pin 3 of the socket XS1, and the other end of the resistor R1 is respectively connected to the capacitor C3, the capacitor C2 and the differential amplifier module.

[0037] Specifically, in the present embodiment, the differential amplifier module includes a preamplifier chip U1 and a resistor R3; pin 1 of the preamplifier chip U1 is connected to the resistor R3, the other end of the resistor R3 is connected to pin 8 of the preamplifier chip U1, pin 2 of the preamplifier chip U1 is connected to the first passive filtering circuit, pin 3 of the preamplifier chip U1 is connected to the second passive filtering circuit, pin 4 of the preamplifier chip U1 is respectively connected to the power supply end and capacitor C4, the other end of the capacitor C4 is respectively connected to capacitor C5 and the ground end, the other end of the capacitor C5 is respectively connected to the power supply end and pin 7 of the preamplifier chip U1, pin 5 of the preamplifier chip U1 is grounded, and pin 6 of the preamplifier chip U1 is connected to the first polarization processing module; the differential amplifier module is used to realize differential amplification of electrode input signals, which can effectively filter out common-mode signals, that is, offset common-mode voltages, wherein the amplification factor of the differential amplifier module can be controlled by resistor R2.

[0038] Specifically, in this embodiment, the first polarization processing module is used to filter out the polarization voltage of the induced voltage, that is, to filter out the polarization voltage formed between the electrodes; the first polarization processing module includes a low-pass filter and an amplifier; the low-pass filter is used to extract the polarization interference signal of the induced voltage received from the differential amplifier module, that is, the polarization noise; the low-pass filter is respectively connected to the differential amplifier module, the amplifier and the second polarization processing module, and the amplifier is connected to the differential amplifier module; the low-pass filter adopts an eighth-order Butterworth low-pass filter, and the transition band of the low-pass filter is very narrow. The size of the cut-off frequency f can be adjusted between 1Hz-2kHz by an external capacitor. By adjusting the cut-off frequency f, the polarization voltage above the cut-off frequency f can be blocked, that is, the polarization voltage above the working frequency of the excitation cycle can be filtered out by adjusting the low-pass filter; the amplifier obtains the signal after polarization filtering by differentially dividing the signal obtained from the differential amplifier module with the polarization interference signal extracted by the low-pass filter.

[0039] Specifically, in the present embodiment, the second polarization processing module includes a subtractor unit, a reference voltage input unit, a DAC feedback adjustment unit and a main control unit; the main control unit is electrically connected to the ADC sampling module and the DAC feedback adjustment unit, respectively, the DAC feedback adjustment unit is electrically connected to the subtractor unit, the subtractor unit is electrically connected to the first polarization processing module, and the reference voltage input unit is electrically connected to the subtractor unit, the reference voltage accumulation and amplification module and the ADC sampling module, respectively; wherein the reference voltage input unit includes a first reference voltage input unit and a second reference voltage input unit, the first reference voltage input unit is connected to the reference voltage accumulation and amplification module and the subtractor unit, respectively, and the second reference voltage input unit is connected to the ADC sampling module; the first reference voltage unit The first reference voltage of the element is 1.25V, which is not specifically limited in the present invention and can be set according to needs; the second reference voltage input unit is used to provide the ADC sampling module with a second reference voltage for ADC conversion; the second polarization processing module is used to filter out the polarization voltage interference at and below the operating frequency, and obtain the current signal after the polarization voltage is completely filtered out; the main control unit uses the data obtained from the ADC sampling module to feedback and adjust the DAC feedback adjustment unit. Because there is no excitation and no induced voltage, the signal of the electrode is basically polarization or DC bias. The collected polarization voltage is used for feedback adjustment to control the DAC feedback adjustment unit to output an analog voltage value to offset the polarization voltage during the excitation cycle, thereby retaining the current signal; wherein, the polarization voltage will not produce a sudden change, it is only an electron migration process.

[0040] Specifically, in this embodiment, the subtractor unit includes a subtractor U6, a resistor R8 and a capacitor C18; pin 1 of the subtractor U6 is connected to the first polarization processing module, pin 2 of the subtractor U6 is grounded, pin 3 of the subtractor U6 is connected to the first reference voltage input unit, pin 4 of the subtractor U6 is connected to the DAC feedback adjustment unit, and pin 5 of the subtractor U6 is connected to the power supply terminal.

[0041] Specifically, in this embodiment, the reference voltage accumulation and amplification module includes an amplifier U7, a capacitor R9, a resistor R10, a resistor R11, a capacitor C19, a capacitor C20, a resistor R12 and a third passive filtering circuit; pin 1 of the amplifier U7 is connected to the third passive filtering circuit, and the third passive filtering circuit is respectively connected to the second polarization processing module and the ADC sampling module, pin 2 of the amplifier U7 is respectively connected to the power supply end and the capacitor C20, pin 3 of the amplifier U7 is respectively connected to the resistor R9 and the resistor R10, and the other end of the resistor R10 is connected to the second polarization processing module. The processing module is connected, the 4-pin of the amplifier U7 is connected to the resistor R11, the other end of the resistor R11 is connected to the first polarization processing module, the 5-pin of the amplifier U7 is connected to the power supply end and the capacitor C19 respectively, and the other ends of the capacitor C19, the capacitor C20 and the resistor R9 are grounded; the reference voltage accumulation and amplification module is used for secondary amplification of the signal and adds a reference voltage, that is, the first reference voltage, in order to avoid the voltage value of the signal being negative, because the ADC sampling module cannot convert negative voltages and amplify the current signal at the same time, and the accumulated first reference voltage is not amplified.

[0042] Specifically, in this embodiment, the ADC sampling module is a 24-bit ADC sampling module, which samples a 24-bit sampling ADC chip with high resolution. The ADC sampling module is used to collect the amplified signal, perform ADC conversion, and obtain AD values ​​of multiple groups of induced voltages of the electromagnetic water meter. The AD values ​​include polarization voltage and current signals. The purpose of the present invention is to completely filter out the polarization voltage.

[0043] See also Figure 5 According to one aspect of the present invention, the present invention provides a metering method for polarization voltage processing of an electromagnetic water meter, comprising the following steps:

[0044] S1. The main control unit is periodically excited, and the electrode input module collects the induced voltage of the excitation coil and amplifies it through the differential amplifier module;

[0045] S2, the first polarization processing module performs a polarization process on the collected induced voltage;

[0046] S3, the second polarization processing module performs secondary polarization processing on the induced voltage after the primary polarization processing;

[0047] S4, the reference voltage accumulation and amplification module amplifies the induced voltage after the secondary polarization processing, and simultaneously adds a reference voltage, and the ADC sampling module performs ADC conversion;

[0048] S5. Obtain multiple groups of AD values ​​of induced voltages, establish a comparative relationship between the AD value of the electromagnetic water meter and the flow velocity, calculate the flow signal of the electromagnetic water meter according to the caliber and flow velocity of the electromagnetic water meter, and return to step S1.

[0049] Specifically, in this embodiment, the second polarization processing module uses the voltage value of the DAC feedback adjustment unit and the signal obtained by the reference voltage input unit through the subtractor unit as the reverse reference voltage of the first polarization processing module according to the AD value fed back by the ADC sampling module, thereby eliminating the polarization voltage below the operating frequency; specifically:

[0050] The main control unit turns off the excitation and obtains the polarization voltage of the electrode in the non-excitation state;

[0051] The polarization voltage is amplified by the differential amplifier module, and the polarization voltage above the excitation cycle frequency is eliminated by the first polarization processing module, and then accumulated and amplified by the reference voltage accumulation and amplification module, and ADC conversion is performed by the ADC sampling module to obtain multiple groups of AD values, and the average value of the multiple groups of AD values ​​is calculated; the average value of the multiple groups of AD values ​​is: A = (a1 + a2 + ... + a i ) / i; where A is the average value of multiple groups of AD values, a i is the AD value of group i;

[0052] The DAC feedback adjustment unit converts the polarization voltage collected by the ADC sampling module into an analog voltage, and reversely subtracts the analog voltage from the subtractor unit to obtain a first signal; the first signal is the current signal after the polarization voltage is completely filtered out.

[0053] Specifically, in this embodiment, due to the differences in the electrodes of large-diameter electromagnetic water meters, polarization voltage is easily generated, resulting in saturation of the AD value after amplification, resulting in inaccurate measurement. The present invention filters out the polarization voltage above the operating frequency through the first polarization processing module, and then uses DAC feedback adjustment through the second polarization processing module to filter out the polarization voltage interference below and near the operating frequency, so that the final sampled AD value is a complete current signal, thereby improving the measurement accuracy of the electromagnetic water meter.

[0054] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A metering system for polarization voltage processing of electromagnetic water meters, characterized in that: include: An electrode input module, a differential amplification module, a first polarization processing module, a second polarization processing module, a reference voltage accumulation and amplification module and an ADC sampling module; the electrode input module, the differential amplification module, the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module are electrically connected in sequence, the output end of the ADC sampling module is electrically connected to the input end of the second polarization processing module, and the output end of the second polarization processing module is electrically connected to the input ends of the first polarization processing module, the reference voltage accumulation and amplification module and the ADC sampling module respectively.

2. The metering system for polarization voltage processing of electromagnetic water meter according to claim 1 is characterized in that: The electrode input module is used to detect the electrode signal and collect the induced voltage of the excitation coil; the electrode input module includes a socket XS1, a first passive filtering circuit, a second passive filtering circuit and a capacitor C2; the socket is respectively connected to the electrode, the first passive filtering circuit, the second passive filtering circuit and the ground, the first passive filtering circuit is respectively connected to the capacitor C2, the differential amplifier module and the ground, and the other end of the capacitor C2 is respectively connected to the second passive filtering circuit, the differential amplifier module and the ground.

3. The metering system for polarization voltage processing of electromagnetic water meter according to claim 2 is characterized in that: The first passive filtering circuit includes a resistor R1 and a capacitor C1; one end of the resistor R1 is connected to pin 1 of the socket XS1, and the other end of the resistor R1 is connected to the capacitor C1, the capacitor C2 and the differential amplifier module respectively.

4. The metering system for polarization voltage processing of electromagnetic water meter according to claim 2, characterized in that: The second passive filtering circuit includes a resistor R2 and a capacitor C3; one end of the resistor R2 is connected to pin 3 of the socket XS1, and the other end of the resistor R1 is connected to the capacitor C3, the capacitor C2 and the differential amplifier module respectively.

5. A metering system for polarization voltage processing of an electromagnetic water meter according to any one of claims 1 to 4, characterized in that: The first polarization processing module is used to filter out the polarization voltage of the induced voltage; the first polarization processing module includes a low-pass filter and an amplifier; the low-pass filter is respectively connected to the differential amplification module, the amplifier and the second polarization processing module, and the amplifier is connected to the differential amplification module.

6. A metering system for polarization voltage processing of an electromagnetic water meter according to any one of claims 1 to 4, characterized in that: The second polarization processing module includes a subtractor unit, a reference voltage input unit, a DAC feedback adjustment unit and a main control unit; the main control unit is electrically connected to the ADC sampling module and the DAC feedback adjustment unit, respectively, the DAC feedback adjustment unit is electrically connected to the subtractor unit, the subtractor unit is electrically connected to the first polarization processing module, and the reference voltage input unit is electrically connected to the subtractor unit, the reference voltage accumulation and amplification module and the ADC sampling module, respectively.

7. A metering system for polarization voltage processing of an electromagnetic water meter according to any one of claims 1 to 4, characterized in that: The reference voltage accumulation and amplification module includes an amplifier U7, a capacitor R9, a resistor R10, a resistor R11, a capacitor C19, a capacitor C20, a resistor R12 and a third passive filtering circuit; pin 1 of the amplifier U7 is connected to the third passive filtering circuit, and the third passive filtering circuit is respectively connected to the second polarization processing module and the ADC sampling module, pin 2 of the amplifier U7 is respectively connected to the power supply end and the capacitor C20, pin 3 of the amplifier U7 is respectively connected to the resistor R9 and the resistor R10, and the other end of the resistor R10 is connected to the second polarization processing module, pin 4 of the amplifier U7 is connected to the resistor R11, and the other end of the resistor R11 is connected to the first polarization processing module, pin 5 of the amplifier U7 is respectively connected to the power supply end and the capacitor C19, and the other ends of the capacitor C19, the capacitor C20 and the resistor R9 are grounded.

8. A metering system for polarization voltage processing of an electromagnetic water meter according to any one of claims 1 to 4, characterized in that: The ADC sampling module is a 24-bit ADC sampling module.

9. A metering method comprising a metering system for electromagnetic water meter polarization voltage processing according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the main control unit is periodically excited, the electrode input module collects the induced voltage of the excitation coil, and amplifies it through the differential amplifier module; S2, the first polarization processing module performs a polarization process on the collected induced voltage; S3, the second polarization processing module performs secondary polarization processing on the induced voltage after the primary polarization processing; S4, the reference voltage accumulation and amplification module amplifies the induced voltage after the secondary polarization processing, and simultaneously adds a reference voltage, and the ADC sampling module performs ADC conversion; S5. Obtain multiple groups of AD values ​​of induced voltages, establish a comparative relationship between the AD value of the electromagnetic water meter and the flow velocity, calculate the flow signal of the electromagnetic water meter according to the caliber and flow velocity of the electromagnetic water meter, and return to step S1.

10. The metering method for polarization voltage processing of electromagnetic water meter according to claim 9, characterized in that: The step S3 is specifically: The main control unit turns off the excitation and obtains the polarization voltage of the electrode in the non-excitation state; The polarization voltage is amplified by the differential amplifier module, and the polarization voltage above the excitation cycle frequency is eliminated by the first polarization processing module, and then accumulated and amplified by the reference voltage accumulation and amplification module, and ADC conversion is performed by the ADC sampling module to obtain multiple groups of AD values, and the average value of the multiple groups of AD values ​​is calculated; The DAC feedback adjustment unit converts the polarization voltage collected by the ADC sampling module into an analog voltage, and reversely subtracts the analog voltage from the subtractor unit to obtain a first signal.

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