An electromagnetic water meter converter

Abstract

The present invention is applicable to the technical field of electromagnetic water meters, and relates to an electromagnetic water meter converter, including: an excitation coil, a self-checking circuit, an excitation circuit, an amplifying and filtering circuit, and an A / D conversion circuit; the self-checking circuit includes a first analog switch U4 and a second analog switch U5, the self-checking circuit is connected to the amplifying and filtering circuit, the first analog switch U4 is connected to the sensor and the amplifying and filtering circuit respectively, the second analog switch U5 is connected to the excitation coil and the excitation circuit respectively, and the amplifying and filtering circuit is also connected to the A / D conversion circuit. The present invention adds a self-checking circuit to the converter, outputs a fixed flow signal through analog switch control, when an infrared or key sends a self-checking command, the converter enters a self-checking mode, switches the analog switch, and adjusts the converter instrument coefficient by detecting the fixed flow signal, so that the interchangeability of the electromagnetic water meter converter can be achieved without an external signal generator, and it can be judged whether the converter is normal.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic water meters, and in particular relates to an electromagnetic water meter converter. Background Art

[0002] The converter of the electromagnetic water meter has poor consistency due to the differences in its components, board manufacturing and production. In the case of the same sensor, the replacement of the converter requires recalibration. At present, in order to achieve the interchangeability of the converter, a signal generator dedicated to the electromagnetic flowmeter is generally used. The converter is connected to the signal generator, the value collected by the converter is compared with the signal generator, and the instrument coefficient is adjusted to make it correspond, thereby achieving the consistency of the converter. This method is more troublesome and cumbersome. It requires an external signal generator and cannot detect the quality and accuracy of the converter during use.

[0003] The patent with announcement number CN113252146B provides an intelligent flow velocity simulation system, which includes: a flow velocity sensing voltage output unit, a flow velocity direction switching unit, and a noise signal simulation unit; the flow velocity sensing voltage output unit is connected to the electromagnetic water meter converter, and the excitation current generated by the electromagnetic water meter converter is converted into an induced voltage corresponding to the flow velocity and output; the input end of the flow velocity direction switching unit is connected to the output end of the flow velocity sensing voltage output unit, and the output end of the flow velocity direction switching unit is connected to the input end of the electromagnetic water meter converter, and the flow direction of the induced voltage signal is controlled by the flow velocity direction switching unit; the noise signal simulation unit includes a noise signal generator, the GND of the noise signal generator is connected to the analog ground port of the electromagnetic water meter converter, the output end of the noise generator is connected to the GND of the intelligent flow velocity simulation system, and the noise signal generator simulates a common mode noise signal input to the analog ground end of the electromagnetic water meter converter. In this patent, communication is carried out in the form of connecting the signal generator to the converter, the process is cumbersome, and there are the same disadvantages as the prior art.

[0004] Therefore, how to provide an electromagnetic water meter converter that can achieve interchangeability of electromagnetic water meter converters without the need for an external signal generator and can determine whether the converter is normal is an urgent problem to be solved by personnel in this technical field. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an electromagnetic water meter converter to solve the problems in the prior art that the process of achieving interchangeability of electromagnetic water meter converters is rather troublesome and the quality and accuracy of the converter cannot be detected during use; in addition, the present invention also provides a method for using the electromagnetic water meter converter.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides an electromagnetic water meter converter, comprising:

[0008] Sensor, excitation coil, self-test circuit, excitation circuit, amplifier and filter circuit, A / D conversion circuit;

[0009] The self-test circuit includes a first analog switch U4 and a second analog switch U5. The self-test circuit is connected to the amplifying and filtering circuit. The first analog switch U4 is connected to the sensor and the amplifying and filtering circuit respectively. The second analog switch U5 is connected to the excitation coil and the excitation circuit respectively. The amplifying and filtering circuit is also connected to the A / D conversion circuit. The first analog switch U4 includes an analog switch U4A and an analog switch U4B. When the electromagnetic water meter works normally, the common end COM of the analog switch U4A is connected to the SIG1 end of the amplifying and filtering circuit and is turned on with its own NO0 end. The common end COM of the analog switch U4B is connected to the SIG2 end of the amplifying and filtering circuit and is turned on with its own NO0 end. The second analog switch U5 includes an analog switch U5A and an analog switch U5B. When the electromagnetic water meter During normal operation, the common terminal COM of the analog switch U5A is connected to the CD1 terminal of the excitation circuit and is conducted with its own NO0 terminal, and the common terminal COM of the analog switch U5B is connected to the CD2 terminal of the excitation circuit and is conducted with its own NO0 terminal; when the electromagnetic water meter enters the self-test mode through infrared or button operation, the common terminal COM of the analog switch U4A is connected to the SIG1 terminal of the amplifying and filtering circuit and is conducted with its own NO1 terminal, and the common terminal COM of the analog switch U4B is connected to the SIG2 terminal of the amplifying and filtering circuit and is conducted with its own NO1 terminal; the common terminal COM of the analog switch U5A is connected to the CD1 terminal of the excitation circuit and is conducted with its own NO1 terminal, and the common terminal COM of the analog switch U5B is connected to the CD2 terminal of the excitation circuit and is conducted with its own NO1 terminal.

[0010] Furthermore, the self-test circuit also includes resistors R5, R6, R7, R8, R9, and R10. The NO1 end of the analog switch U4A is respectively connected to one end of the resistor R5 and one end of the resistor R7, the other end of the resistor R5 is connected to one end of the resistor R6, the other end of the resistor R6 and one end of the resistor R8 are respectively connected to the NO1 end of the analog switch U4B, the other end of the resistor R7 and one end of the resistor R9 are respectively connected to the NO1 end of the analog switch U5A, the other end of the resistor R9 is connected to one end of the resistor R10, and the other end of the resistor R10 and the other end of the resistor R8 are respectively connected to the NO1 end of the analog switch U5B.

[0011] Further, the excitation circuit includes an amplifier U1, a resistor R1, a resistor R2, a MOS tube V1, a MOS tube Q1, a MOS tube Q2, a MOS tube Q3, and a MOS tube Q4. The drain of the MOS tube Q1 and the drain of the MOS tube Q2 are both externally connected to a power supply. The source of the MOS tube Q1 and the drain of the MOS tube Q3 are both connected to the CD1 end of the excitation circuit. The source of the MOS tube Q2 and the drain of the MOS tube Q4 are both connected to the CD2 end of the excitation circuit. The source of the MOS tube Q3 and the source of the MOS tube Q4 are both connected to the drain of the MOS tube V1. The gate of the MOS tube V1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the output end of the amplifier U1. The amplifier U1 inputs a voltage to the positive input end, and the reverse input end of the amplifier U1 and the source of the MOS tube V1 are both connected to one end of the resistor R2, and the other end of the resistor R2 is grounded.

[0012] Furthermore, the amplifying and filtering circuit includes a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, an amplifier U3, and a resistor RG, one end of the resistor R3 is respectively connected to one end of the capacitor C1 and one end of the capacitor C2, the other end of the resistor R3 is connected to the SIG2 end, one end of the resistor R4 is respectively connected to the other end of the capacitor C2 and one end of the capacitor C3, the other end of the resistor R4 is connected to the SIG1 end, one end of the capacitor C1 and one end of the capacitor C2 are also respectively connected to the -IN end of the amplifier U3, the other end of the capacitor C2 and one end of the capacitor C3 are also respectively connected to the +IN end of the amplifier U3, and the two ends of the resistor RG are respectively connected to the two RG ends of the amplifier U3.

[0013] Furthermore, the OUT terminal of the amplifier U3 is connected to the AIN0 terminal of the analog-to-digital converter U2 of the A / D conversion circuit, and the REF terminal of the amplifier U3 is connected to the AIN1 terminal of the analog-to-digital converter U2.

[0014] Compared with the prior art, the electromagnetic water meter converter provided by the present invention has at least the following beneficial effects:

[0015] In order to achieve the interchangeability of the converter in the prior art, a signal generator dedicated to the electromagnetic flowmeter is generally used. This method is relatively troublesome and the process is cumbersome. An external signal generator is required, and the quality and accuracy of the converter cannot be detected during use. The present invention adds a self-test circuit to the converter, which outputs a fixed flow signal through analog switch control. When the infrared or key sends a self-test command, the converter enters the self-test mode, switches the analog switch, and adjusts the converter instrument coefficient by detecting the fixed flow signal. The interchangeability of the electromagnetic water meter converter can be achieved without an external signal generator, and it can be judged whether the converter is normal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the scheme of the present invention, a brief introduction is given below to the figures required for use in the description of the embodiments. Obviously, the figures described below are some embodiments of the present invention. For ordinary technicians in this field, other figures can be obtained based on these figures without paying any creative work.

[0017] Figure 1 A structural block diagram of an electromagnetic water meter converter provided by an embodiment of the present invention;

[0018] Figure 2 A self-test circuit diagram of an electromagnetic water meter converter provided by an embodiment of the present invention;

[0019] Figure 3 An excitation circuit diagram of an electromagnetic water meter converter provided by an embodiment of the present invention;

[0020] Figure 4 A filter amplifying circuit diagram of an electromagnetic water meter converter provided by an embodiment of the present invention;

[0021] Figure 5 An A / D conversion circuit diagram of an electromagnetic water meter converter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention; the terms used in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the terms "length", "width", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or locations based on the positions or locations shown in the drawings, which are only for the convenience of description and cannot be understood as limiting the present technical solution. The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second" and the like in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In the specification and claims of the present invention and the above-mentioned drawings, when an element is referred to as "fixed to" or "mounted on" or "set on" or "connected to" another element, it may be directly or indirectly located on the other element. For example, when an element is referred to as "connected to" another element, it may be directly or indirectly connected to the other element. In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] The present invention provides an electromagnetic water meter converter, which is used in realizing the interchangeability of converters of electromagnetic water meters. The electromagnetic water meter converter includes:

[0024] Excitation coil, self-checking circuit, excitation circuit, amplification and filtering circuit, A / D conversion circuit; the self-checking circuit includes a first analog switch U4 and a second analog switch U5, the self-checking circuit is connected to the amplification and filtering circuit, the first analog switch U4 is connected to the sensor and the amplification and filtering circuit respectively, the second analog switch U5 is connected to the excitation coil and the excitation circuit respectively, and the amplification and filtering circuit is also connected to the A / D conversion circuit; the first analog switch U4 includes an analog switch U4A and an analog switch U4B, when the electromagnetic water meter works normally, the common terminal COM of the analog switch U4A is connected to the SIG1 terminal of the amplification and filtering circuit, and is turned on with its own NO0 terminal, the common terminal COM of the analog switch U4B is connected to the SIG2 terminal of the amplification and filtering circuit, and is turned on with its own NO0 terminal; the second analog switch U5 includes an analog switch U5A and Analog switch U5B, when the electromagnetic water meter works normally, the common terminal COM of the analog switch U5A is connected to the CD1 terminal of the excitation circuit and is connected to its own NO0 terminal, and the common terminal COM of the analog switch U5B is connected to the CD2 terminal of the excitation circuit and is connected to its own NO0 terminal; when the electromagnetic water meter enters the self-test mode through infrared or button operation, the common terminal COM of the analog switch U4A is connected to the SIG1 terminal of the amplifier and filter circuit and is connected to its own NO1 terminal, and the common terminal COM of the analog switch U4B is connected to the SIG2 terminal of the amplifier and filter circuit and is connected to its own NO1 terminal; the common terminal COM of the analog switch U5A is connected to the CD1 terminal of the excitation circuit and is connected to its own NO1 terminal, and the common terminal COM of the analog switch U5B is connected to the CD2 terminal of the excitation circuit and is connected to its own NO1 terminal.

[0025] The present invention adds a self-checking circuit to the converter, and outputs a fixed flow signal through analog switch control. When a self-checking command is sent by infrared or a key, the converter enters a self-checking mode, switches the analog switch, and adjusts the instrument coefficient of the converter by detecting the fixed flow signal. The interchangeability of the electromagnetic water meter converter can be achieved without an external signal generator, and it can be judged whether the converter is normal.

[0026] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0027] The present invention provides an electromagnetic water meter converter, which is used in realizing the interchangeability of converters of electromagnetic water meters. Figures 1 to 5 In this embodiment, the electromagnetic water meter converter includes:

[0028] Sensor, excitation coil, self-check circuit, excitation circuit, amplification filter circuit, A / D conversion circuit; the self-check circuit includes a first analog switch U4 and a second analog switch U5, the self-check circuit is connected to the amplification filter circuit, the first analog switch U4 is connected to the sensor and the amplification filter circuit respectively, the second analog switch U5 is connected to the excitation coil and the excitation circuit respectively, and the amplification filter circuit is also connected to the A / D conversion circuit. Under normal working conditions, the excitation coil is directly connected to the excitation circuit, and a constant current that periodically switches positive and negative flows into the excitation coil to generate a magnetic field. When the fluid cuts the magnetic flux lines, a voltage signal with the same frequency and different magnitude as the excitation signal is generated on the sensor. The voltage signal is processed by the amplification filter circuit and enters the A / D conversion circuit to be converted into the flow required by the user. The embodiment of the present invention adds a self-test circuit on the basis of a normal circuit. The self-test circuit includes a first analog switch and a second analog switch. When a button or an infrared command is pressed to enter the self-test mode, the first analog switch and the second analog switch are switched to the self-test circuit. A constant current signal switched forward and reversely by the excitation circuit flows into the self-test circuit to generate a flow signal. The signal passes through an amplifying and filtering circuit and enters an A / D conversion circuit to become a flow rate. The flow rate is compared with a set amount, and the instrument coefficient is calculated and saved.

[0029] Furthermore, in the present embodiment, the excitation circuit includes an amplifier U1, a resistor R1, a resistor R2, a MOS transistor V1, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, and a MOS transistor Q4. The drain of the MOS transistor Q1 and the drain of the MOS transistor Q2 are both connected to an external power supply. The source of the MOS transistor Q1 and the drain of the MOS transistor Q3 are both connected to the CD1 end of the excitation circuit. The source of the MOS transistor Q2 and the drain of the MOS transistor Q4 are both connected to the CD2 end of the excitation circuit. The source of the MOS transistor Q3 and the source of the MOS transistor Q4 are both connected to the drain of the MOS transistor V1. The gate of the MOS transistor V1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the output end of the amplifier U1. A voltage is input to the positive input end of the amplifier U1. The reverse input end of the amplifier U1 and the source of the MOS transistor V1 are both connected to one end of the resistor R2, and the other end of the resistor R2 is grounded.

[0030] Specifically, in this embodiment, an amplifier U1, a resistor R1, a precision resistor R2, and a MOS tube V1 form a constant current source generating circuit, the current size is determined by VIN and the resistor R2, the current I=VIN / R2, VIN is a stable voltage, MOS tubes Q1, MOS tubes Q2, MOS tubes Q3, and MOS tubes Q4 form an H-bridge circuit, which is controlled on and off by a single-chip microcomputer, wherein MOS tubes Q1 and MOS tubes Q4 are a pair, and are switched at the same time, and so are MOS tubes Q2 and MOS tubes Q3, CD1 end and CD2 end are connected to the coil, and when working, the current first flows from MOS tube Q1 to CD1 end, passes through the coil to CD2 end, and then to MOS tube Q4 to form a path; then it is periodically switched to the current from MOS tube Q2 to CD2 end, flows through the coil to CD1 end, and then to MOS tube Q3, to achieve forward and reverse excitation of the coil.

[0031] Furthermore, in the present embodiment, the amplifying and filtering circuit includes a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, an amplifier U3, and a resistor RG. One end of the resistor R3 is connected to one end of the capacitor C1 and one end of the capacitor C2, respectively. The other end of the resistor R3 is connected to the SIG2 end. One end of the resistor R4 is connected to the other end of the capacitor C2 and one end of the capacitor C3, respectively. The other end of the resistor R4 is connected to the SIG1 end. One end of the capacitor C1 and one end of the capacitor C2 are also connected to the -IN end of the amplifier U3, respectively. The other end of the capacitor C2 and one end of the capacitor C3 are also connected to the +IN end of the amplifier U3, respectively. The two ends of the resistor RG are connected to the two RG ends of the amplifier U3, respectively.

[0032] Specifically, in this embodiment, the resistor R3, the resistor R4, the capacitor C1, the capacitor C2, and the capacitor C3 form a low-pass filter, and the high-precision instrument amplifier U3 and the precision resistor RG form an amplifier circuit.

[0033] Furthermore, in this embodiment, the OUT terminal of the amplifier U3 is connected to the AIN0 terminal of the analog-to-digital converter U2 of the A / D conversion circuit, and the REF terminal of the amplifier U3 is connected to the AIN1 terminal of the analog-to-digital converter U2. The signal processed by the amplification and filtering circuit enters the analog-to-digital converter U2.

[0034] Furthermore, in the present embodiment, the self-test circuit also includes resistors R5, R6, R7, R8, R9, and R10; the NO1 end of the analog switch U4A is connected to one end of the resistor R5 and one end of the resistor R7, respectively; the other end of the resistor R5 is connected to one end of the resistor R6; the other end of the resistor R6 and one end of the resistor R8 are connected to the NO1 end of the analog switch U4B, respectively; the other end of the resistor R7 and one end of the resistor R9 are connected to the NO1 end of the analog switch U5A, respectively; the other end of the resistor R9 is connected to one end of the resistor R10; the other end of the resistor R10 and the other end of the resistor R8 are connected to the NO1 end of the analog switch U5B, respectively.

[0035] Specifically, in this embodiment, when the electromagnetic water meter is working normally, SIG1 and SIG2 (amplifier signal input) connected to the common end COM of the analog switch U4A and the analog switch U4B of the first analog switch U4 are turned on with NO0, that is, they are turned on with the sensor signal ends S1 and S2, and CD1 and CD2 (excitation circuit connected to the load interface) connected to the common end COM of the analog switch U5A and the analog switch U5B of the second analog switch U5 are turned on with NO0, that is, they are turned on with the excitation coil E1 and the excitation coil E2. At this time, the coil is periodically excited in forward and reverse directions. When the fluid flows through, it cuts the magnetic flux lines and generates a flow signal at the sensor end. The flow signal goes through S1 and S2 to SIG1 and SIG2, is processed by the amplification and filtering circuit, and enters the A / D conversion circuit.

[0036] When the electromagnetic water meter enters the self-test mode through infrared or button operation, the microcontroller controls the pin IN to send an enable signal, and the SIG1 and SIG2 (amplifier signal input) connected to the common end COM of the analog switch U4A and the analog switch U4B of the first analog switch U4 are turned on, and the NO1 connected to the common end COM of the analog switch U5A and the analog switch U5B of the second analog switch U5 is turned on. At this time, the excitation current flows through the resistor R9 and the resistor R10 (R9 and R10 are precision resistors of tens of ohms, simulating the resistance of the coil, R5 and R6 are resistors of the same resistance, R7 and R8 are resistors of the same resistance, and both are above 1K), then the voltage between R9 and R10 U≈(R9+R10)*I (where I is the excitation current), the input signal U1=R5 / (R5+R7)*U= R6 / (R6+R8)*U, adjust the resistance ratio of R5, R6, R7, and R8 to make the input voltage U1 close to the original signal voltage value at a flow rate of 1m / s (other values ​​within the measuring range are also acceptable). After the amplification and filtering circuit and the A / D conversion circuit, the calculated flow velocity is V, then the instrument coefficient K=1 / V*1.000, the instrument coefficient defaults to 1.000, and the error range does not exceed 3‰.

[0037] When electromagnetic water meter converters are produced, infrared self-test commands can be sent in batches. The converter automatically calculates the meter coefficient K and saves it. At this time, the converter completes the consistency test, which is convenient and quick.

[0038] When the electromagnetic water meter is in use, the self-test command can be sent manually or periodically and automatically. The converter uses the saved instrument coefficient K and the self-test flow rate V to calculate whether V*K is equal to the preset flow rate 1m / s (error range 3‰). If it is within this range, the converter is normal; if it exceeds this range, the error is greater than 3‰ and less than 5%, the converter is offset, and the instrument coefficient of the converter is automatically adjusted. The error is recorded and reported; if the error is greater than 5%, the converter is seriously offset, or the device is seriously aged, the instrument coefficient of the converter is adjusted, and an alarm is issued to remind the user to replace the converter.

[0039] Compared with the prior art, the electromagnetic water meter converter described in the above embodiment generally uses a signal generator dedicated to the electromagnetic flowmeter to achieve the interchangeability of the converter. This method is troublesome and cumbersome, and requires an external signal generator, and cannot detect the quality and accuracy of the converter during use. The present invention adds a self-test circuit to the converter, which outputs a fixed flow signal through analog switch control. When the infrared or key sends a self-test command, the converter enters the self-test mode, switches the analog switch, and adjusts the converter instrument coefficient by detecting the fixed flow signal. The interchangeability of the electromagnetic water meter converter can be achieved without an external signal generator, and it can be judged whether the converter is normal.

[0040] Obviously, the embodiments described above are only preferred embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are shown in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific embodiments, or to perform equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. An electromagnetic water meter converter, characterized in that: include: Sensor, excitation coil, self-test circuit, excitation circuit, amplifier and filter circuit, A / D conversion circuit; The self-test circuit includes a first analog switch U4 and a second analog switch U5, the self-test circuit is connected to the amplifying and filtering circuit, the first analog switch U4 is connected to the sensor and the amplifying and filtering circuit respectively, the second analog switch U5 is connected to the excitation coil and the excitation circuit respectively, and the amplifying and filtering circuit is also connected to the A / D conversion circuit; The first analog switch U4 includes an analog switch U4A and an analog switch U4B. When the electromagnetic water meter works normally, the common end COM of the analog switch U4A is connected to the SIG1 end of the amplifying and filtering circuit and is conducted with its own NO0 end. The common end COM of the analog switch U4B is connected to the SIG2 end of the amplifying and filtering circuit and is conducted with its own NO0 end. The second analog switch U5 includes an analog switch U5A and an analog switch U5B. When the electromagnetic water meter works normally, the common end COM of the analog switch U5A is connected to the CD1 end of the excitation circuit and is conducted with its own NO0 end. The common end COM of the analog switch U5B is connected to the CD2 end of the excitation circuit and is conducted with its own NO0 end. When the electromagnetic water meter enters the self-test mode through infrared or button operation, the common terminal COM of the analog switch U4A is connected to the SIG1 terminal of the amplifying and filtering circuit, and is conducted with its own NO1 terminal, and the common terminal COM of the analog switch U4B is connected to the SIG2 terminal of the amplifying and filtering circuit, and is conducted with its own NO1 terminal; the common terminal COM of the analog switch U5A is connected to the CD1 terminal of the excitation circuit, and is conducted with its own NO1 terminal, and the common terminal COM of the analog switch U5B is connected to the CD2 terminal of the excitation circuit, and is conducted with its own NO1 terminal; The self-test circuit also includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a resistor R10. The NO1 end of the analog switch U4A is connected to one end of the resistor R5 and one end of the resistor R7, respectively. The other end of the resistor R5 is connected to one end of the resistor R6. The other end of the resistor R6 and one end of the resistor R8 are connected to the NO1 end of the analog switch U4B, respectively. The other end of the resistor R7 and one end of the resistor R9 are connected to the NO1 end of the analog switch U5A, respectively. The other end of the resistor R9 is connected to one end of the resistor R10. The other end of the resistor R10 and the other end of the resistor R8 are connected to the NO1 end of the analog switch U5B, respectively. When entering the self-test mode, the excitation current flows through resistors R9 and R10, and the voltage U between R9 and R10 and the input voltage U1=R5 / (R5+R7)*U=R6 / (R6+R8)*U are calculated. The resistance ratio of R5, R6, R7, and R8 is adjusted to make the input voltage U1 close to the original signal voltage value at the preset flow rate. The flow rate V is calculated, and it is determined whether V*K is equal to the preset flow rate, where K is the instrument factor, to determine whether the converter is normal.

2. An electromagnetic water meter converter according to claim 1, characterized in that: The excitation circuit includes an amplifier U1, a resistor R1, a resistor R2, a MOS transistor V1, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, and a MOS transistor Q4. The drain of the MOS transistor Q1 and the drain of the MOS transistor Q2 are both externally connected to a power supply. The source of the MOS transistor Q1 and the drain of the MOS transistor Q3 are both connected to the CD1 end of the excitation circuit. The source of the MOS transistor Q2 and the drain of the MOS transistor Q4 are both connected to the CD2 end of the excitation circuit. The source of the MOS transistor Q3 and the source of the MOS transistor Q4 are both connected to the drain of the MOS transistor V1. The gate of the MOS transistor V1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the output end of the amplifier U1. A voltage is input to the positive input end of the amplifier U1. The reverse input end of the amplifier U1 and the source of the MOS transistor V1 are both connected to one end of the resistor R2, and the other end of the resistor R2 is grounded.

3. An electromagnetic water meter converter according to claim 1, characterized in that: The amplifying and filtering circuit includes a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, an amplifier U3, and a resistor RG. One end of the resistor R3 is connected to one end of the capacitor C1 and one end of the capacitor C2, respectively. The other end of the resistor R3 is connected to the SIG2 end. One end of the resistor R4 is connected to the other end of the capacitor C2 and one end of the capacitor C3, respectively. The other end of the resistor R4 is connected to the SIG1 end. One end of the capacitor C1 and one end of the capacitor C2 are also connected to the -IN end of the amplifier U3, respectively. The other end of the capacitor C2 and one end of the capacitor C3 are also connected to the +IN end of the amplifier U3, respectively. The two ends of the resistor RG are connected to the two RG ends of the amplifier U3, respectively.

4. An electromagnetic water meter converter according to claim 3, characterized in that: The OUT terminal of the amplifier U3 is connected to the AIN0 terminal of the analog-to-digital converter U2 of the A / D conversion circuit, and the REF terminal of the amplifier U3 is connected to the AIN1 terminal of the analog-to-digital converter U2.

Images