Constant current source control circuit of large-caliber electromagnetic water meter

Abstract

The utility model is suitable for the technical field of electromagnetic water meters, and relates to a constant current source control circuit of a large-caliber electromagnetic water meter, which comprises an excitation power supply module, an excitation conversion module, a constant current control module, an excitation coil, an excitation coil voltage detection module, a digital potentiometer control module and an MCU (Microprogrammed Control Unit) main control module, the excitation source power supply module, the excitation conversion module, the constant current control module, the excitation coil and the excitation coil voltage detection module are in communication connection in sequence, and the MCU main control module is in communication connection with the excitation source power supply module, the excitation conversion module, the digital potentiometer control module and the excitation coil terminal voltage detection module. And the constant current control module is in communication connection with the digital potentiometer control module. The large-caliber electromagnetic water meter is simple in structure and convenient to operate, and stability and accuracy of long-term working of the large-caliber electromagnetic water meter are effectively guaranteed.

Description

Technical Field

[0001] This utility model belongs to the field of electromagnetic water meter technology, and in particular relates to a constant current source control circuit for a large-diameter electromagnetic water meter. Background Technology

[0002] Large-diameter electromagnetic water meters typically operate in humid or even submerged environments. Humidity can easily cause aging of the excitation coil inside the meter, leading to a fundamental change in the induced electromotive force (EMF) generated by the same excitation current before and after aging, directly affecting the accuracy of measurement. Large-diameter electromagnetic water meters are generally battery-powered, with a constant current source at a specific value. Considering power consumption, the excitation current is typically between 15 and 20 milliamps. However, under this excitation current, the induced EMF in a large-diameter electromagnetic water meter is only a few tens of microvolts, resulting in a very weak signal. As the excitation coil ages, the induced EMF decreases further, and the noise does not decrease. Even after conditioning, the metering signal remains undetectable, leading to inaccurate or even non-measuring measurements.

[0003] Patent CN113566911B discloses an excitation control method, device, and storage medium for an electromagnetic water meter. The electromagnetic water meter contains a coil, and its control method includes inputting excitation currents of different excitation cycles into the coil and real-time acquiring the induced voltage signal generated when the coil receives the input current. Based on the acquired induced voltage signal, the water flow velocity corresponding to multiple different excitation cycles is calculated, and the water flow velocities of multiple different excitation cycles are compared. Based on the comparison result, the corresponding excitation cycle is switched. Although this patent involves a control method for an electromagnetic water meter, its purpose is to reduce power consumption. It does not provide a technical solution for overcoming the defect of the aging excitation coil affecting the metering accuracy of the electromagnetic water meter.

[0004] Therefore, ensuring the stability and accuracy of large-diameter electromagnetic water meters during long-term operation is a problem that urgently needs to be solved by personnel in this technical field. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a constant current source control circuit for a large-diameter electromagnetic water meter, thereby solving the problem that the stability and accuracy of electromagnetic water meters cannot be guaranteed during long-term operation in existing technologies.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This utility model provides a constant current source control circuit for a large-diameter electromagnetic water meter, including:

[0008] The system comprises an excitation power supply module, an excitation conversion module, a constant current control module, an excitation coil, an excitation coil voltage detection module, a digital potentiometer control module, and an MCU main control module. The excitation power supply module, excitation conversion module, constant current control module, excitation coil, and excitation coil voltage detection module are sequentially and communicatively connected. The MCU main control module is communicatively connected to each of these modules. The constant current control module is communicatively connected to the digital potentiometer control module.

[0009] Furthermore, the circuit of the excitation power supply module includes a chip U4, and the MCU main control module is connected to the fourth pin of the chip U4 to control the power supply on and off.

[0010] Furthermore, the circuit of the excitation conversion module includes MOSFETs V2, V3, V4, and V5, switch L1, and switch L2. One end of switch L1 is connected to the third pin of MOSFET V2 and the third pin of MOSFET V4, respectively, and the other end of switch L1 is connected to the first pin of the excitation coil. One end of switch L2 is connected to the third pin of MOSFET V3 and the third pin of MOSFET V5, respectively, and the other end of switch L2 is connected to the second pin of the excitation coil. The second pin of MOSFET V2 is connected to the second pin of MOSFET V3, and the second pin of MOSFET V4 is connected to the second pin of MOSFET V5.

[0011] Furthermore, the constant current control module circuit includes a chip U1, an amplifier U2, resistors R1 and R2, and a MOSFET V1. The 8th pin of the chip U1 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the 3rd pin of the amplifier U2, the 4th pin of the amplifier U2 is connected to the 2nd pin of the MOSFET V1, and the 1st pin of the amplifier U2 is connected to the 1st pin of the MOSFET V1.

[0012] Furthermore, the circuit of the digital potentiometer control module includes a chip U3, the sixth pin of which is connected to the fourth pin of the amplifier U2 and also to the second pin of the MOS transistor V1.

[0013] Furthermore, the circuit of the excitation coil voltage detection module includes transistors V9, V10, V11, and V12. The third pin of transistor V9 is connected to the first pin of transistor V10, the switch L1 is connected to the second pin of transistor V10, the third pin of transistor V11 is connected to the first pin of transistor V12, and the switch L2 is connected to the second pin of transistor V12.

[0014] Compared with the prior art, the constant current source control circuit for the large-diameter electromagnetic water meter provided by this utility model has at least the following advantages:

[0015] In existing technologies, large-diameter electromagnetic water meters are primarily battery-powered, with a constant current source operating at a specific value. Considering power consumption, the excitation current is typically between 15 and 20 milliamps. However, under this excitation current, the induced electromotive force (EMF) in large-diameter electromagnetic water meters is only a few tens of microvolts, resulting in a very weak signal. As the excitation coil ages, the induced EMF decreases further, and noise does not decrease. Even after conditioning, the metering signal remains undetectable, leading to inaccurate or even non-measuring readings. This invention features a simple structure and convenient operation. Based on the law of conservation of energy, and the principle that the total energy consumed by the excitation coil and the energy converted into magnetic energy remain constant, the excitation current is adaptively adjusted. When a signal is detected within a very small range, the excitation current is adaptively increased to detect even extremely weak signals, maintaining a stable magnetic field. This ensures that the generated induced EMF, under the same flow rate, will not be missed or ignored due to coil aging, achieving the goal of maintaining normal flow even after the excitation coil ages. This improves the long-term stability and accuracy of the electromagnetic water meter. Attached Figure Description

[0016] To more clearly illustrate the solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 A module block diagram of a constant current source control circuit for a large-diameter electromagnetic water meter provided for an embodiment of this utility model;

[0018] Figure 2 A partial circuit diagram of a constant current source control circuit for a large-diameter electromagnetic water meter provided in this embodiment of the utility model;

[0019] Figure 3 A circuit diagram of the excitation power supply module in the constant current source control circuit of a large-diameter electromagnetic water meter provided for an embodiment of this utility model;

[0020] Figure 4 The circuit diagram of the excitation coil voltage detection module in the constant current source control circuit of a large-diameter electromagnetic water meter provided for an embodiment of this utility model. Detailed Implementation

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as “length,” “width,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” indicate orientations or positions based on the orientations or positions shown in the accompanying drawings and are merely for ease of description and should not be construed as limiting the invention.

[0022] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this utility model are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish different objects, not to describe a particular order. In the specification, claims, and accompanying drawings of this utility model, when an element is referred to as "fixed to," "mounted to," "set on," or "connected to" another element, it can be directly or indirectly located on that other element. For example, when an element is referred to as "connected to" another element, it can be directly or indirectly connected to that other element.

[0023] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] This utility model provides a constant current source control circuit for a large-diameter electromagnetic water meter, applied to solve the problem of inaccurate measurement caused by long-term operation of large-diameter electromagnetic water meters. The constant current source control circuit for the large-diameter electromagnetic water meter includes:

[0025] The system comprises an excitation power supply module, an excitation conversion module, a constant current control module, an excitation coil, an excitation coil terminal voltage detection module, a digital potentiometer control module, and an MCU main control module. The excitation power supply module, excitation conversion module, constant current control module, excitation coil, and excitation coil terminal voltage detection module are sequentially connected for communication. The MCU main control module is also connected for communication with the excitation power supply module, excitation conversion module, digital potentiometer control module, and excitation coil terminal voltage detection module. The constant current control module is also connected for communication with the digital potentiometer control module.

[0026] This utility model has a simple structure and is easy to operate, effectively ensuring the stability and accuracy of large-diameter electromagnetic water meters during long-term operation.

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0028] This utility model provides a constant current source control circuit for a large-diameter electromagnetic water meter, which is used to solve the problem of inaccurate measurement caused by long-term operation of large-diameter electromagnetic water meters. The principle of this utility model embodiment is based on the principle of energy conservation. Due to the aging or oxidation of the excitation coil, the internal resistance will increase. Under the same excitation current, the voltage difference consumed on the internal resistance of the excitation coil will increase, and the amount of magnetic energy converted will decrease.

[0029] Specifically, the excitation supply voltage U is constant. Before aging, the voltage difference of the excitation coil I1 under constant excitation current is ΔU1. Therefore, the energy generated and converted into magnetic energy is Q1=(U-ΔU1)I1.

[0030] After aging, the supply voltage U is constant. Before aging, the voltage difference of the excitation coil under constant excitation current I2 is ΔU2. Therefore, the energy that can be converted into magnetic energy is Q2=(U-ΔU2)I2.

[0031] To maintain traffic stability, Q1 = Q2 is required;

[0032] Therefore, the internal resistance of the excitation coil increases after aging, ΔU2 increases, and I2 increases. This is the principle of adaptive adjustment.

[0033] like Figure 1 As shown, in this embodiment, the constant current source control circuit for the large-diameter electromagnetic water meter includes:

[0034] The system comprises an excitation power supply module, an excitation conversion module, a constant current control module, an excitation coil, an excitation coil terminal voltage detection module, a digital potentiometer control module, and an MCU main control module. These modules are sequentially connected for communication. The MCU main control module is also connected to each of these modules. The constant current control module is connected to the digital potentiometer control module. The excitation power supply module supplies power to the excitation conversion module, which generates a periodically switching voltage signal. The constant current control module uses a voltage-controlled current method to provide a stable current. The excitation coil voltage detection module converts the voltage into a signal that the MCU can acquire. The MCU main control module controls and calls upon each module.

[0035] Furthermore, in this embodiment, the circuit of the excitation power supply module includes a chip U4, and the MCU main control module is connected to the fourth pin of the chip U4 to control the power supply on and off.

[0036] Specifically, the excitation power supply module uses a boost circuit, where EVCC is the excitation voltage, and the main control MCU controls the power supply on and off by controlling EN.

[0037] Furthermore, in this embodiment, the circuit of the excitation conversion module includes MOSFETs V2, V3, V4, and V5, switch L1, and switch L2. One end of switch L1 is connected to the third pin of MOSFET V2 and the third pin of MOSFET V4, respectively, and the other end of switch L1 is connected to the first pin of the excitation coil. One end of switch L2 is connected to the third pin of MOSFET V3 and the third pin of MOSFET V5, respectively, and the other end of switch L2 is connected to the second pin of the excitation coil. The second pin of MOSFET V2 is connected to the second pin of MOSFET V3, and the second pin of MOSFET V4 is connected to the second pin of MOSFET V5.

[0038] Specifically, MOSFETs V2, V3, V4, and V5 form an H-bridge circuit, which is controlled by the main control MCU. MOSFETs V4 and V3 are a pair and switch simultaneously, as are MOSFETs V5 and V2. Switches L1 and L2 are connected to the excitation coil. During operation, the current first flows from MOSFET V4 to switch L1, through the excitation coil to switch L2, and then to MOSFET V3 to form a path. Then, it periodically switches to the current flowing from MOSFET V5 to switch L2, through the excitation coil to switch L1, and then to MOSFET V2, realizing the forward and reverse excitation conversion of the coil.

[0039] Furthermore, in this embodiment, the constant current control module circuit includes a chip U1, an amplifier U2, resistors R1 and R2, and a MOSFET V1. The 8th pin of the chip U1 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the 3rd pin of the amplifier U2, the 4th pin of the amplifier U2 is connected to the 2nd pin of the MOSFET V1, and the 1st pin of the amplifier U2 is connected to the 1st pin of the MOSFET V1.

[0040] Specifically, the constant current control module generates a stable voltage using chip U1, which is a voltage regulator. The voltage regulator divides the voltage through resistors R1 and R2, where resistors R1 and R2 are high-precision resistors. The stable control voltage is assumed to be U′. A constant current is generated through voltage-controlled current amplifier U2, MOSFET V1, and the digital potentiometer control module, with resistor R′ assumed to be constant. The current of the constant current source is I′=U′ / R′. Considering power consumption, the initial value of the constant current source is approximately 15mA.

[0041] Furthermore, in this embodiment, the circuit of the digital potentiometer module includes a chip U3, the 6th pin of the chip U3 is connected to the 4th pin of the amplifier U2, and is also connected to the 2nd pin of the MOS transistor V1.

[0042] Specifically, the U3 chip uses a digital potentiometer chip with an I2C interface, 10-bit resolution, and a maximum resistance of 1K. The resistance can be adjusted to 1K / 1024 = 0.9766 ohms, allowing for precise adjustment.

[0043] Furthermore, in this embodiment, the circuit of the excitation coil voltage detection module includes transistors V9, V10, V11, and V12. The third pin of transistor V9 is connected to the first pin of transistor V10, switch L1 is connected to the second pin of transistor V10, the third pin of transistor V11 is connected to the first pin of transistor V12, and switch L2 is connected to the second pin of transistor V12.

[0044] Specifically, the MCU main control module controls L-EN, turns on transistors V9, V10, V11, and V12, and the voltage across the excitation coil, the voltage of switches L1 and L2 are divided by resistors and sent to the ADC inside the main control MCU for conversion, and the main control MCU processes the voltage.

[0045] Compared with existing technologies, the constant current source control circuit for large-diameter electromagnetic water meters described in the above embodiments differs significantly. Existing large-diameter electromagnetic water meters are primarily battery-powered, with the constant current source typically set to a specific value. Considering power consumption, the excitation current is generally between 15 and 20 mA. However, under this excitation current, the induced electromotive force in a large-diameter electromagnetic water meter is only a few tens of microvolts, resulting in a very weak signal. As the excitation coil ages, the induced electromotive force decreases further, and noise is not reduced. Even after conditioning, the metering signal remains undetectable, leading to inaccurate or even non-measuring readings. This invention features a simple structure and convenient operation. Based on the law of conservation of energy, and the principle that the total energy consumed by the excitation coil and its conversion into magnetic energy remains constant, the excitation current is adaptively adjusted. When a signal is detected within a very small range, the excitation current is adaptively increased to detect even extremely weak signals, maintaining a stable magnetic field. Consequently, the generated induced electromotive force, under the same flow rate, will not be missed or ignored due to coil aging. This achieves the goal of maintaining normal flow even after the excitation coil ages, improving the long-term stability and accuracy of the electromagnetic water meter.

[0046] Obviously, the embodiments described above are merely preferred embodiments of this utility model, and not all embodiments. The accompanying drawings show preferred embodiments of this utility model, but do not limit the patent scope of this utility model. This utility model can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this utility model.

Claims

1. A constant current source control circuit for a large-diameter electromagnetic water meter, characterized in that, include: The system comprises an excitation power supply module, an excitation conversion module, a constant current control module, an excitation coil, an excitation coil voltage detection module, a digital potentiometer control module, and an MCU main control module. The excitation power supply module, excitation conversion module, constant current control module, excitation coil, and excitation coil voltage detection module are sequentially and communicatively connected. The MCU main control module is communicatively connected to each of these modules. The constant current control module is communicatively connected to the digital potentiometer control module.

2. The constant current source control circuit for a large-diameter electromagnetic water meter according to claim 1, characterized in that, The circuit of the excitation power supply module includes a chip U4, and the MCU main control module is connected to the fourth pin of the chip U4 to control the power supply on and off.

3. The constant current source control circuit for a large-diameter electromagnetic water meter according to claim 1, characterized in that, The circuit of the excitation conversion module includes MOSFETs V2, V3, V4, and V5, switch L1, and switch L2. One end of switch L1 is connected to the third pin of MOSFET V2 and the third pin of MOSFET V4, respectively. The other end of switch L1 is connected to the first pin of the excitation coil. One end of switch L2 is connected to the third pin of MOSFET V3 and the third pin of MOSFET V5, respectively. The other end of switch L2 is connected to the second pin of the excitation coil. The second pin of MOSFET V2 is connected to the second pin of MOSFET V3. The second pin of MOSFET V4 is connected to the second pin of MOSFET V5.

4. The constant current source control circuit for a large-diameter electromagnetic water meter according to claim 1, characterized in that, The constant current control module circuit includes a chip U1, an amplifier U2, resistors R1 and R2, and a MOSFET V1. The 8th pin of the chip U1 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the 3rd pin of the amplifier U2, the 4th pin of the amplifier U2 is connected to the 2nd pin of the MOSFET V1, and the 1st pin of the amplifier U2 is connected to the 1st pin of the MOSFET V1.

5. The constant current source control circuit for a large-diameter electromagnetic water meter according to claim 4, characterized in that, The circuit of the digital potentiometer control module includes a chip U3, the sixth pin of which is connected to the fourth pin of the amplifier U2 and also to the second pin of the MOS transistor V1.

6. The constant current source control circuit for a large-diameter electromagnetic water meter according to claim 3, characterized in that, The circuit of the excitation coil voltage detection module includes transistors V9, V10, V11, and V12. The third pin of transistor V9 is connected to the first pin of transistor V10, the switch L1 is connected to the second pin of transistor V10, the third pin of transistor V11 is connected to the first pin of transistor V12, and the switch L2 is connected to the second pin of transistor V12.

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