An electromagnetic flowmeter with empty pipe detection circuit

Abstract

The application discloses an electromagnetic flowmeter with empty tube detection circuit, which comprises a control module, the control module comprises a micro-control processing module, an empty tube detection circuit electrically connected with the micro-control processing module, a signal conditioning module and an excitation conditioning module, the excitation conditioning module comprises a constant current source circuit, the signal conditioning module comprises a signal amplification circuit of at least two amplification circuits and a signal filtering circuit. The empty tube detection circuit can realize the empty tube detection function, the empty tube judgment can be completed by reading high and low levels, thereby the empty tube protection is carried out, the power consumption is reduced, the system stability and safety are maintained, the application has the advantages of small imbalance, small temperature drift and good linearity; the constant current source circuit in the excitation conditioning module can keep constant current, the multiple signal amplification circuits and the signal filtering circuit in the signal conditioning module can amplify and filter multiple times, thereby effectively amplifying and processing the weak induced electromotive force, and the measurement accuracy is ensured.

Description

Technical Field

[0001] This invention relates to the field of flow detection technology, and more particularly to an electromagnetic flowmeter with an empty pipe detection circuit. Background Technology

[0002] An electromagnetic flowmeter is an instrument used to measure the flow velocity of liquids. Based on Faraday's law of electromagnetic induction, it utilizes the potential difference generated when a conductive liquid (usually water) moves in a magnetic field to measure the flow velocity. It is widely used in industrial automation, water treatment, chemical, food, and pharmaceutical industries. The main characteristics of electromagnetic flowmeters include: measurement is unaffected by changes in fluid temperature and density; the fluid does not pass through mechanical devices, avoiding dynamic pressure loss; it has unique adaptability to slurry measurement; it can output a linear analog signal or frequency signal with a wide measurement range directly proportional to the flow velocity; and it uses low-frequency square wave excitation, resulting in long-term stability and high accuracy.

[0003] An electromagnetic flowmeter mainly consists of an electromagnetic flow sensor, a signal conditioning circuit, an excitation drive circuit, a microcontroller, and a communication output circuit. The excitation drive circuit uses a low-frequency rectangular excitation square wave to generate a stable and controllable alternating current. This current, passing through the sensor's coil, generates a constant magnetic field. Two stainless steel electrode plates are located on either side of the sensor. When the conductive medium flows within the measuring pipe, it perpendicularly cuts the magnetic field lines, generating a weak induced electromotive force proportional to the volumetric flow rate between a pair of electrodes mounted on the pipe wall, perpendicular to both the flow direction and the magnetic field direction. This weak voltage signal is amplified by the signal conditioning circuit and then converted into a digital signal by an analog-to-digital converter (ADC), which is then input to the microcontroller. Finally, the microcontroller displays the data as corresponding flow velocity and calculated flow rate information on the screen, or converts it into a 485 signal or a 4~20mA analog current signal via an RS485 chip and outputs it to an external device, completing the final measurement of the liquid flow velocity and flow rate.

[0004] However, existing electromagnetic flowmeters cannot be used well in harsh environments such as coal mines, and have problems such as low accuracy, susceptibility to environmental damage, and high failure rate. Summary of the Invention

[0005] Therefore, the purpose of this invention is to at least partially address the shortcomings of the prior art, thereby proposing an electromagnetic flowmeter with an empty pipe detection circuit.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an electromagnetic flowmeter with an empty pipe detection circuit, comprising a control module. The control module includes a microcontroller processing module, an empty pipe detection circuit, a signal conditioning module, and an excitation conditioning module. The microcontroller processing module is electrically connected to the empty pipe detection circuit, the signal conditioning module, and the excitation conditioning module. The excitation conditioning module includes a constant current source circuit, and the signal conditioning module includes a signal amplification circuit and a signal filtering circuit with at least two amplification circuits.

[0007] Furthermore, the empty pipe detection circuit includes a detection circuit and a conditioning circuit. The detection circuit includes a counter, the output of which is connected to the conditioning circuit, and the output of the conditioning circuit is connected to the microcontroller processing module. The conditioning circuit includes a frequency-to-voltage conversion chip, a comparator, and a first capacitor. The frequency-to-voltage conversion chip is connected in parallel with the first capacitor and is also connected to the counter. The VOUT terminal of the frequency-to-voltage conversion chip is connected to the comparator.

[0008] Furthermore, the excitation conditioning module also includes an excitation signal generation circuit, which is electrically connected to the constant current source circuit. The excitation signal generation circuit includes interconnected electromagnetic coils and an H-bridge chip. The H-bridge chip is connected to a first, second, third, and fourth field-effect transistor. The H-bridge chip is also connected to the microcontroller processing module. The constant current source circuit includes a power supply chip, a first amplifier, a second amplifier, a voltage reference source, a first resistor, and a fifth field-effect transistor. The output terminal of the first amplifier is connected to the N1S / N2S terminal of the H-bridge chip, and the inverting input terminal is connected to the power supply chip. The non-inverting input terminal of the second amplifier is connected to the voltage reference source, the inverting input terminal is connected to the first resistor, and the output terminal is connected to the gate of the fifth field-effect transistor.

[0009] Furthermore, the signal amplification circuit includes a first-stage amplification circuit and a second-stage amplification circuit. The first-stage amplification circuit includes an instrumentation amplifier, a second resistor, and a third amplifier. The non-inverting and inverting input terminals of the instrumentation amplifier are both connected to the second resistor, and its output terminal is connected to the non-inverting input terminal of the third amplifier. The reference signal input terminal is connected to the signal filtering circuit. The second-stage amplification circuit includes a fourth amplifier, a fifth amplifier, and a third resistor. The output terminal of the fourth amplifier is connected to the inverting input terminal and the output terminal of the fifth amplifier. Its non-inverting input terminal is connected to the output terminal of the signal filtering circuit through the third resistor. The output terminal of the fifth amplifier is connected to the microcontroller processing module.

[0010] Furthermore, the signal filtering circuit includes an electrically connected RC low-pass filter circuit and an integral feedback circuit. The RC low-pass filter circuit includes a sixth amplifier, a fourth resistor, and a second capacitor. The non-inverting input terminal of the sixth amplifier is connected to the fourth resistor and the second capacitor, and its output terminal is connected to the non-inverting input terminal of the fourth amplifier through the third resistor. The integral feedback circuit includes a seventh amplifier, a fifth resistor, and a third capacitor. The signal output terminal of the seventh amplifier is connected to the reference signal input terminal of the instrumentation amplifier, and its inverting input terminal is connected to the signal output terminal of the instrumentation amplifier through the fifth resistor. Both the inverting input terminal and the output terminal are connected to the third capacitor.

[0011] Furthermore, the microcontroller processing module includes an MCU and an ADC converter. The MCU is electrically connected to the ADC converter. The PB3, PB4, PB5, and PB6 pins of the MCU are connected to the SCLK, CS#, DOUT, and DIN pins of the ADC converter, respectively. The signal input terminal of the ADC converter is connected to the output terminal of the fifth amplifier.

[0012] Furthermore, the control module also includes a human-machine interface module electrically connected to the microcontroller processing module. The human-machine interface module includes buttons, a display device, and a memory chip. One end of the button is connected to the high level of the MCU, and the other end is connected to the IO port of the MCU and pulled down to ground. The display device includes a display screen and a display chip connected to each other. The display chip is connected to the PB12, PB13, PB15, PDS, PD9, PD10, PD11, and PD7 pins of the MCU. The WC#, SCL, and SDA pins of the memory chip are connected to the PE15, PB10, and PB11 pins of the MCU, respectively.

[0013] Furthermore, the control module also includes a communication output module electrically connected to the microcontroller processing module. The communication output module includes a communication circuit and a current circuit. The communication circuit includes a communication chip. The three signal output terminals of the MCU are respectively connected to the receiver output terminal, driver input terminal, and driver enable terminal of the communication chip through an optocoupler chip and a two-channel digital isolator. The receiver output enable terminal of the communication chip is connected to the driver enable terminal. The current circuit includes a current output chip. A pair of IIC signal ports of the MCU are connected to the IIC signal ports of the current output chip through an IIC digital isolator. The current output chip is also connected to the output terminal of an eighth amplifier.

[0014] Furthermore, the control module also includes a power drive module electrically connected to the microcontroller processing module. The power drive module includes a power converter and a power supply unit electrically connected to each other. The power converter is connected to the MCU through a voltage conversion chip.

[0015] Furthermore, it also includes electrodes and a sensor electrically connected to the control module. The control module, electromagnetic coil, sensor, and electrodes are connected to the pipe under test. The pipe under test includes a first pipe and a second pipe connected to each other. A connecting member is connected to each side of the first pipe. The electrodes are provided on both sides of the first pipe. The sensor is located between the two electrodes. The control module is located on the second pipe.

[0016] This invention provides an electromagnetic flowmeter with an empty pipe detection circuit. The control module of the electromagnetic flowmeter includes a microcontroller processing module, an empty pipe detection circuit, an excitation conditioning module including a constant current source circuit, and a signal amplification circuit and a signal filtering circuit. The empty pipe detection circuit can realize the empty pipe detection function. It can complete the empty pipe judgment and thus perform empty pipe protection simply by reading the high and low levels, reducing power consumption and maintaining system stability and safety. It has the advantages of low offset, low temperature drift, good linearity, and stable and adjustable gain. The constant current source circuit of the excitation conditioning module adopts dual voltage and current feedback, which improves the stability of operation compared with traditional current sources and ensures that the direction and magnitude of the magnetic field are controllable. The multi-stage amplification circuit and filtering circuit of the signal conditioning module realize multiple amplification and filtering to effectively amplify the weak induced electromotive force, while ensuring measurement accuracy. This solves the problems of low accuracy, easy damage, and high failure rate of mechanical flowmeters in harsh environments such as coal mines, which are not suitable for use in harsh environments such as coal mines. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the electromagnetic flowmeter with an empty pipe detection circuit according to the present invention. Figure 2 This is a side view of the electromagnetic flowmeter with an empty pipe detection circuit according to the present invention. Figure 3 This is a structural block diagram of the electromagnetic flowmeter with an empty pipe detection circuit according to the present invention; Figure 4 This is a schematic diagram of the detection circuit in the empty pipe detection circuit of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention. Figure 5 This is a schematic diagram of the conditioning circuit in the empty pipe detection circuit of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention. Figure 6 This is a circuit diagram of the excitation conditioning module of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention. Figure 7 This is a circuit diagram of the signal conditioning module of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention. Figure 8 This is a circuit diagram of the microcontroller processing module of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention. Figure 9 This is a circuit diagram of the human-machine interaction module of the electromagnetic flowmeter with empty pipe detection circuit of the present invention. Figure 10 This is a circuit diagram of the communication output module of the electromagnetic flowmeter with an empty pipe detection circuit of the present invention.

[0019] The reference numerals in the figure are as follows: 1-Pipe under test; 11-First pipe; 111-Connecting component; 12-Second pipe; 2-Electromagnetic coil; 3-Control module; 31-Empty pipe detection circuit; 32-Excitation conditioning module; 33-Signal conditioning module; 34-Microcontroller processing module; 341-MCU; 342-ADC converter; 35-Human-machine interaction module; 351-Button; 352-Display component; 36-Communication output module; 361-Communication circuit; 362-Current circuit; 37-Power drive module; 371-Power converter; 372-Lithium battery; 4-Electrode; 5-Sensor. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the descriptions involving "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0022] Please refer to Figures 1 to 10 This invention provides an electromagnetic flowmeter with an empty pipe detection circuit, including a control module 3. The control module 3 includes a microcontroller processing module 34, an empty pipe detection circuit 31, a signal conditioning module 33, and an excitation conditioning module 32. The microcontroller processing module 34 is electrically connected to the empty pipe detection circuit 31, the signal conditioning module 33, and the excitation conditioning module 32. The excitation conditioning module 32 includes a constant current source circuit, and the signal conditioning module 33 includes a signal amplification circuit and a signal filtering circuit with at least two amplification circuits.

[0023] In this embodiment, the control module 3 includes a microcontroller processing module 34, an empty pipe detection circuit 31, a signal conditioning module 33, and an excitation conditioning module 32. The empty pipe detection circuit 31, the signal conditioning module 33, and the excitation conditioning module 32 are electrically connected to the microcontroller processing module 34. The microcontroller processing module 34 generates two complementary low-frequency rectangular excitation square waves, enabling the excitation conditioning module 32 to obtain an alternating, constant-magnitude current. The excitation conditioning module 32 also includes a constant current source circuit, employing dual voltage and current feedback, which improves operational stability compared to traditional current sources and ensures controllable magnetic field direction and magnitude. The signal conditioning module 33 acquires the electromagnetic flow voltage signal, amplifies and filters the signal, and finally transmits it to the microcontroller processing module 34. The signal conditioning module 33 includes multiple signal amplification and filtering circuits, effectively amplifying weak flow signals while ensuring the accuracy of the electromagnetic flowmeter measurement. The empty pipe detection circuit 31 determines whether the pipe under test is in an empty pipe state, thus providing empty pipe protection, reducing power consumption, and maintaining system stability and safety. It has advantages such as low offset, low temperature drift, low linearity, and stable and adjustable gain, effectively controlling empty pipe signal interference and reducing system power consumption under fault conditions. The empty pipe detection function implemented by the empty pipe detection circuit 31 is convenient, meaning it does not require redundant and complex connections to achieve empty pipe detection and early warning functions.

[0024] Furthermore, the air traffic control detection circuit 31 includes a detection circuit and a conditioning circuit. The detection circuit includes a counter, the output of which is connected to the conditioning circuit, and the output of the conditioning circuit is connected to the microcontroller processing module 34. The conditioning circuit includes a frequency-to-voltage conversion chip, a comparator, and a first capacitor. The frequency-to-voltage conversion chip is connected in parallel with the first capacitor and is connected to the counter. The VOUT terminal of the frequency-to-voltage conversion chip is connected to the comparator.

[0025] In this embodiment, the detection circuit includes a counter U11. The output of the counter U11 is connected to a conditioning circuit, and the output of the conditioning circuit is connected to the signal input of the microcontroller processing module 34. When the detection circuit detects that the pipe under test is empty or full (the voltage signals are different when the pipe is empty and full), it transmits the detected signal to the counter U11. This causes a change in the frequency of the signal generated by the square wave output circuit (i.e., the detection circuit) formed by the counter U11. The signal generated by the counter U11 is then input to the conditioning circuit. The specific model of the counter U11 is NE555DR.

[0026] The conditioning circuit includes a frequency-to-voltage conversion chip U22, a comparator U23, and a first capacitor C17. When the counter U11 inputs the generated signal to the frequency-to-voltage conversion chip U22, the chip charges the first capacitor C17 when the input signal is low. As the frequency increases, the charge injected into the first capacitor C17 increases proportionally, thus creating a linear relationship between the voltage at the VOUT terminal of the frequency-to-voltage conversion chip U22 and the input frequency. The comparator U23 compares the voltage at the VOUT terminal with a pre-set reference threshold voltage. The microprocessor control module 34 can then determine whether a flow meter is empty by reading the high or low level output of the comparator U23, exhibiting high sensitivity. This method eliminates the need for an analog-to-digital converter or the frequency measurement function of the microprocessor control module 34, and also avoids complex processing algorithms, reducing the computational resource consumption of the microprocessor control module 34 for empty flow meter detection and effectively lowering the microprocessor's clock frequency requirements for the flow meter system. Among them, the specific model of the frequency-to-voltage conversion chip U22 is ADVFC32, and the specific model of the comparator U23 is LM339.

[0027] Furthermore, the excitation conditioning module 32 also includes an excitation signal generation circuit, which is electrically connected to the constant current source circuit. The excitation signal generation circuit includes an electromagnetic coil 2 and an H-bridge chip connected to each other. The H-bridge chip is connected to a first, second, third, and fourth field-effect transistor. The H-bridge chip is also connected to the microcontroller processing module 34. The constant current source circuit includes a power supply chip, a first amplifier, a second amplifier, a voltage reference source, a first resistor, and a fifth field-effect transistor. The output terminal of the first amplifier is connected to the N1S / N2S terminal of the H-bridge chip, and the inverting input terminal is connected to the power supply chip. The non-inverting input terminal of the second amplifier is connected to the voltage reference source, the inverting input terminal is connected to the first resistor, and the output terminal is connected to the gate of the fifth field-effect transistor.

[0028] In this embodiment, the excitation processing module 32 includes an excitation signal generation circuit and a constant current source power supply that are electrically connected. The constant current source circuit adopts dual feedback of voltage and current, which improves the stability of operation compared with the traditional current source and ensures that the direction and magnitude of the magnetic field are controllable.

[0029] The excitation signal generation circuit includes an interconnected electromagnetic coil 2 and an H-bridge chip U1. The H-bridge chip U1 is also connected to a microcontroller module 34. The H-bridge chip U1 is connected to four field-effect transistors (FETs): Q1, Q2, Q3, and Q4. The microcontroller module 34 provides a pair of complementary PWM signals. When the PWM signal is high, the H-bridge chip U1 controls FETs Q1 and Q4 to conduct simultaneously, while FETs Q2 and Q3 are turned off, defining the current as forward. Conversely, when the PWM signal is low, the current is reversed. Alternating current flows through the electromagnetic coil 2, thereby generating a magnetic field. The specific model of the H-bridge chip U1 is ZXMHC3A01N8TC.

[0030] The constant current source circuit includes a power supply chip U2, a first amplifier U3, a second amplifier U4, a voltage reference E2, a first resistor R3, and a fifth field-effect transistor Q5. The first amplifier U3 is connected in the circuit as a voltage follower. Its output is connected to the N1S / N2S terminals of the H-bridge chip U1, using the voltage at that point as feedback input to the power supply chip U2 to regulate the voltage of the constant current source circuit and achieve constant current. The non-inverting input of the second amplifier U4 is connected to the voltage reference E2, while its inverting input is connected to the first resistor R3. Its output is connected to the gate of the N-type fifth field-effect transistor Q5 to adjust its conduction level (equivalent to its equivalent resistance) to achieve constant current. Specifically, the power supply chip U2 is a voltage reference chip CD431, and the first amplifier U3 and the second amplifier U4 are operational amplifier chips TLC277.

[0031] Furthermore, the signal amplification circuit includes a first-stage amplification circuit and a second-stage amplification circuit. The first-stage amplification circuit includes an instrumentation amplifier, a second resistor, and a third amplifier. The second resistor is connected to both the non-inverting and inverting input terminals of the instrumentation amplifier, and its output terminal is connected to the non-inverting input terminal of the third amplifier. The reference signal input terminal is connected to the signal filtering circuit. The second-stage amplification circuit includes a fourth amplifier, a fifth amplifier, and a third resistor. The output terminal of the fourth amplifier is connected to the inverting input terminal and the output terminal of the fifth amplifier. The non-inverting input terminal is connected to the output terminal of the signal filtering circuit through the third resistor. The output terminal of the fifth amplifier is connected to the microcontroller processing module 34.

[0032] In this embodiment, the signal amplification circuit specifically consists of a first-stage amplification circuit and a second-stage amplification circuit. By setting up multiple amplification circuits, the weak flow signal generated in the pipe to be measured can be effectively amplified and processed, while ensuring the measurement accuracy of the electromagnetic flowmeter. It has the advantages of small offset, small temperature drift, good linearity, and stable and adjustable gain.

[0033] The first-stage amplifier circuit includes an instrumentation amplifier U3, a second resistor R6, and a third amplifier U6. The second resistor R6 is connected to both the non-inverting and inverting inputs of instrumentation amplifier U3. The output of instrumentation amplifier U3 is connected to the non-inverting input of the third amplifier U6. The reference signal input of instrumentation amplifier U3 is connected to a signal filtering circuit. Specifically, instrumentation amplifier U3 is model AD8220, and the third amplifier U6 is model TL072 operational amplifier.

[0034] The second-stage amplifier circuit includes a fourth amplifier U9, a fifth amplifier U10, and a third resistor R11. The output of the fourth amplifier U9 is connected to the inverting input and output of the fifth amplifier U10. The non-inverting input of the fourth amplifier U9 is connected to the output of the signal filtering circuit through the third resistor R11. The output of the fifth amplifier U10 is connected to the microcontroller processing module 34. The specific models of the fourth amplifier U9 and the fifth amplifier U10 are operational amplifiers TL072.

[0035] Furthermore, the signal filtering circuit includes an electrically connected RC low-pass filter circuit and an integral feedback circuit. The RC low-pass filter circuit includes a sixth amplifier, a fourth resistor, and a second capacitor. The non-inverting input terminal of the sixth amplifier is connected to the fourth resistor and the second capacitor, and its output terminal is connected to the non-inverting input terminal of the fourth amplifier through a third resistor. The integral feedback circuit includes a seventh amplifier, a fifth resistor, and a third capacitor. The signal output terminal of the seventh amplifier is connected to the reference signal input terminal of the instrumentation amplifier, and its inverting input terminal is connected to the signal output terminal of the instrumentation amplifier through the fifth resistor. Both the inverting input terminal and the output terminal are connected to the third capacitor.

[0036] In this embodiment, the signal filtering circuit is used to filter the signal, thereby enabling better signal amplification. Specifically, the signal filtering circuit includes an electrically connected RC low-pass filter circuit and an integral feedback circuit.

[0037] The RC low-pass filter circuit includes a sixth amplifier U8, a fourth resistor R10, and a second capacitor C2. The non-inverting input of the sixth amplifier U8 is connected to the fourth resistor R10 and the second capacitor C2. The output of the sixth amplifier U8 is connected to the non-inverting input of the fourth amplifier U9 through a third resistor R11. The specific model of the sixth amplifier U8 is an operational amplifier TL072.

[0038] The integral feedback circuit includes a seventh amplifier U7, a fifth resistor R9, and a third capacitor C1. The signal output terminal of the seventh amplifier U7 is connected to the reference signal input terminal of the instrumentation amplifier U6. The inverting input terminal of the seventh amplifier U7 is connected to the signal output terminal of the instrumentation amplifier U6 through the fifth resistor R9. Both the inverting input terminal and the output terminal of the seventh amplifier U7 are connected to the third capacitor C1. The specific model of the seventh amplifier U7 is an operational amplifier TL071.

[0039] Furthermore, the microcontroller processing module 34 includes an MCU341 and an ADC converter 342. The MCU341 is electrically connected to the ADC converter 342. The PB3, PB4, PB5, and PB6 pins of the MCU341 are connected to the SCLK, CS#, DOUT, and DIN pins of the ADC converter 342, respectively. The signal input terminal of the ADC converter 342 is connected to the output terminal of the fifth amplifier.

[0040] In this embodiment, the microcontroller processing module 34 includes an MCU 341 and an ADC converter 342. The MCU 341 and the ADC converter 342 are electrically connected, and multiple pins of the MCU 341 are connected to multiple pins of the ADC converter 342. Specifically, please refer to [link to documentation]. Figure 8 The PB3, PB4, PB5, and PB6 pins of MCUU12 are connected to the SCLK, CS#, DOUT, and DIN pins of ADC converter U13, respectively. The specific model of MCUU12 is a 32-bit microprocessor chip STM32F407, and the specific model of ADC converter U13 is an analog-to-digital converter chip AD7192.

[0041] Specifically, the signal input terminal of the ADC converter 342 is connected to the signal output terminal of the fifth amplifier U10 in the signal conditioning module 33, thereby converting the analog voltage signal into a digital signal and connecting and transmitting it to the PB3, PB4, PB5, and PB6 pins of the MCU341.

[0042] Furthermore, the control module 3 also includes a human-machine interaction module 35 electrically connected to the microcontroller processing module 34. The human-machine interaction module 35 includes a button 351, a display 352, and a memory chip. One end of the button 351 is connected to the high level of the MCU 341, and the other end is connected to the IO port of the MCU 341 and pulled down to ground. The display 352 includes a display screen and a display chip that are connected to each other. The display chip is connected to the PB12, PB13, PB15, PDS, PD9, PD10, PD11, and PD7 pins of the MCU 341. The WC#, SCL, and SDA pins of the memory chip are connected to the PE15, PB10, and PB11 pins of the MCU 341, respectively.

[0043] In this embodiment, the control module 3 further includes a human-machine interaction module 35, which is electrically connected to the microcontroller processing module 34. When the microcontroller processing module 34 acquires the electromagnetic flow signal, it processes and outputs real-time flow rate and flow data, which are then displayed through the human-machine interaction module 35.

[0044] The human-machine interface module 35 includes a button 351, a display 352, and a memory chip U15. Specifically, one end of the button 351 is connected to the high level of the MCU 341, and the other end is connected to the IO port of the MCU 341 and pulled down to ground. When the button 351 is pressed, a high level is output to the MCU 341, which then recognizes the high level, remeasures the flow rate value, and updates it on the display 352. The display 352 also includes a display screen and a display chip U14. The display chip U14 is electrically connected to the MCU 341, thereby controlling the display screen to show the flow rate and accumulated flow data. The pins of the display chip U14 are connected to the PB12, PB13, PB15, PDS, PD9, PD10, PD11, and PD7 pins on the MCU 341. The WC#, SCL, and SDA pins of the memory chip U15 are connected to the PE15, PB10, and PB11 pins of the MCU 341, respectively.

[0045] Furthermore, the control module 3 also includes a communication output module 36 electrically connected to the microcontroller processing module 34. The communication output module 36 includes a communication circuit 361 and a current circuit 362. The communication circuit 361 includes a communication chip. The three signal output terminals of the MCU 341 are respectively connected to the receiver output terminal, driver input terminal, and driver enable terminal of the communication chip through an optocoupler chip and a two-channel digital isolator. The receiver output enable terminal of the communication chip is connected to the driver enable terminal. The current circuit 362 includes a current output chip. A pair of IIC signal ports of the MCU 341 are connected to the IIC signal ports of the current output chip through an IIC digital isolator. The current output chip is also connected to the output terminal of an eighth amplifier.

[0046] In this embodiment, the control module 3 also includes a communication output module 36. The communication output module 36 enables communication between the microcontroller and the PC using various communication methods, which has the advantage of adapting to the development and application of instrument networking. Specifically, the communication output module 36 includes a communication circuit 361 and a current circuit 362. The communication circuit 361 has multi-point, bidirectional communication capabilities, with a maximum transmission rate of 10Mb / s and a transmission distance extended to 1219 meters. The current circuit 362 uses a current-limited signal method to transmit analog signals, avoiding noise and voltage interference in coal mine working conditions.

[0047] Specifically, the communication circuit 361 includes a communication chip U19. The three signal output terminals of the MCU U12 are connected to the receiver output terminal, driver input terminal, and driver enable terminal of the communication chip U19 through an optocoupler chip U16 and a two-channel digital isolator U17, respectively. The receiver output enable terminal of the communication chip U19 is connected to its driver enable terminal. Specifically, the communication chip U19 is a 485 communication chip SP485, the optocoupler chip U16 is an optocoupler chip PC817, and the two-channel data isolator U17 is a digital isolator π122U31.

[0048] The current circuit 362 includes a current output chip U20. A pair of IIC signal ports of the MCU U12 are connected to the IIC signal ports of the current output chip U20 through an IIC digital isolator U18. The current output chip U20 is also connected to the output of the eighth amplifier U21. Specifically, the current output chip U20 is a GP8212S, the IIC digital isolator U18 is an ISO1540DR, and the eighth amplifier U21 is an LM321 operational amplifier.

[0049] Furthermore, the control module 3 also includes a power drive module 37 electrically connected to the microcontroller processing module 34. The power drive module 37 includes a power converter 371 and a power supply unit electrically connected to each other. The power converter 371 is connected to the MCU 341 through a voltage conversion chip.

[0050] In this embodiment, the control module 3 further includes a power drive module 37, which is electrically connected to the microcontroller processing module 34. The power drive module 37 features overvoltage and overcurrent detection, undervoltage detection, and discharge protection detection, ensuring safety and reliability, and has a simple battery replacement mechanism. Specifically, the power drive module 37 includes a power converter 371 and a power supply unit electrically connected, and the power converter 371 is also connected to the MCU 341 via a voltage conversion chip. The power converter 342 can obtain ±5V through the voltage conversion chip to power all modules. The power supply unit is specifically a lithium battery 372, with a rated voltage of 3.6V and a rated capacity of 1.8Ah per cell. In this embodiment, the lithium battery pack consists of four groups of two lithium batteries 372 connected in parallel, with a total capacity of 7.2Ah.

[0051] Furthermore, it also includes an electrode 4 and a sensor 5 electrically connected to the control module 3. The control module 3, the electromagnetic coil 2, the sensor 5 and the electrode 4 are connected to the pipe under test 1. The pipe under test 1 includes a first pipe 11 and a second pipe 12 connected to each other. A connecting piece 111 is connected to each side of the first pipe 11. Electrodes 4 are provided on both sides of the first pipe 11. The sensor 5 is located between the two electrodes 4. The control module 3 is provided on the second pipe 12.

[0052] In this embodiment, the electromagnetic flowmeter with an empty pipe detection circuit includes a pipe to be measured 1, and connecting parts 111 are provided on both sides of the pipe to be measured 1. The connecting parts 111 are used to connect to external pipes, thereby completing the measurement of liquid velocity and flow rate. In this embodiment, the connecting part 111 is specifically a flange. The specific type of the connecting part 111 is not limited here, and is set according to actual production needs.

[0053] The test pipe 1 is also equipped with an electromagnetic coil 2, a sensor 5, an electrode 4, and a control module 3. The test pipe 1 includes a first pipe 11 and a second pipe 12 connected to each other. The two sides of the first pipe 11 are connected to connecting external pipes. Electrodes 4 are respectively provided on the two opposite inner sidewalls of the first pipe 11, and a sensor 5 is provided between the two electrodes 4. In this embodiment, the sensor 5 is specifically an electromagnetic flow sensor. The control module 3 is also provided at the top of the second pipe 12, wherein the top of the second pipe 12 is the side away from the first pipe 11. The control module 3 is also connected to the sensor 5 and the electromagnetic coil 2.

[0054] In this embodiment, the control module 3 generates a stable and controllable alternating current. After the current passes through the coil of the sensor 5, it generates a constant magnetic field. Two electrodes are arranged on both sides of the sensor 5. When the conductive medium flows in the pipe 1 under test, it will cut the magnetic field lines perpendicularly. A weak induced electromotive force proportional to the volumetric flow rate is generated between a pair of electrodes 4 installed on the pipe 1 under test, which are perpendicular to the flow direction and the magnetic field direction. The control module then converts the weak induced electromotive force to complete the final measurement of the liquid flow rate and volume. The input terminal of the counter and the signal input terminal of the signal amplification circuit are connected to the output terminal of the sensor 5. When the sensor 5, which is set in the pipe 1 under test, is connected to the input terminal of the counter U11 and the signal input terminal of the signal amplification circuit, the electromagnetic flow signal in the pipe can be transmitted to the counter U11, thereby detecting whether the pipe 1 under test is empty. The electromagnetic flow signal in the pipe is transmitted to the signal amplification circuit, which can amplify, filter, and convert the weak electromagnetic flow signal to digital, thus obtaining the final measurement of the liquid flow rate and volume.

[0055] Furthermore, the specific implementation steps of this application embodiment are as follows: 1. When the conductive medium flows through the pipe to be tested 1, the microcontroller processing module 31 controls the H-bridge chip U1 in the excitation conditioning module 32 to generate a low-frequency rectangular excitation square wave, thereby obtaining an alternating current with a constant magnitude. 2. Charged particles hit electrode 2 to generate a weak induced electromotive force. The weak induced electromotive force is transmitted to the counter U11 in the empty tube detection circuit 31 through sensor 5, so as to perform empty tube detection. If an empty tube phenomenon is found, the excitation drive is stopped. If it is not found, the weak induced electromotive force is transmitted to the signal amplification circuit through sensor 5. 3. The signal conditioning module 33 filters and amplifies the weak induced electromotive force through multiple signal amplification circuits and filtering circuits. 4. The filtered and amplified analog voltage signal is then transmitted to the ADC converter 342 in the microcontroller processing module 34 and converted into a digital signal; 5. The converted digital signal is then transmitted to the MCU341 in the microcontroller processing module 34 for algorithm processing, thereby outputting real-time flow rate and flow data, which are then displayed through the human-machine interface module 35. The communication circuit and current circuit analog output circuit in the communication output module 36 transmit the signal to a remote terminal, enabling remote viewing of flow data and expanding the application range of the electromagnetic flowmeter.

[0056] The initial electromagnetic flow signal processing method utilizes an improved Kalman filter algorithm. First, a moving average filter is used to preprocess the experimental data, reducing the impact of strong interference noise on the electromagnetic flowmeter during measurement. The interference situation of the electromagnetic flowmeter in the harsh environment of underground coal mines is analyzed, and a residual-based Kalman filter method is proposed. This method enables rapid switching of the process noise covariance Q with flow rate changes, improving the response speed of the Kalman filter and thus enhancing the accuracy of liquid flow velocity measurement.

[0057] In summary, the present invention provides an electromagnetic flowmeter with an empty pipe detection circuit, comprising a control module. The control module includes a microcontroller processing module, an empty pipe detection circuit, a signal conditioning module, and an excitation conditioning module. The microcontroller processing module is electrically connected to the empty pipe detection circuit, the signal conditioning module, and the excitation conditioning module. The excitation conditioning module includes a constant current source circuit, and the signal conditioning module includes a signal amplification circuit and a signal filtering circuit with at least two amplification circuits. The present invention achieves empty pipe detection by incorporating an empty pipe detection circuit into the electromagnetic flowmeter. Empty pipe detection and protection can be performed simply by reading high and low voltage levels, reducing power consumption and maintaining system stability and safety. It offers advantages such as low offset, low temperature drift, good linearity, and stable and adjustable gain. The excitation conditioning module and signal conditioning module effectively amplify and filter weak induced electromotive forces through multiple amplifications, ensuring measurement accuracy. This solves the problems of low accuracy, susceptibility to environmental damage, and high failure rate of mechanical flowmeters in harsh environments such as coal mines, which are unsuitable for use in such environments.

[0058] It should be noted that the various embodiments in the present invention are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0059] It should also be noted that, in the context of this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in the present invention may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown in the present invention, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electromagnetic flowmeter with an empty pipe detection circuit, characterized in that, include: The control module includes a microcontroller processing module, an empty pipe detection circuit, a signal conditioning module, and an excitation conditioning module. The microcontroller processing module is electrically connected to the empty pipe detection circuit, the signal conditioning module, and the excitation conditioning module. The excitation conditioning module includes a constant current source circuit; the signal conditioning module includes a signal amplification circuit and a signal filtering circuit with at least two amplification circuits; the empty tube detection circuit includes a detection circuit and a conditioning circuit; the detection circuit includes a counter, a capacitor, and a resistor, which are connected to form a square wave output circuit; the output terminal of the counter is connected to the conditioning circuit; the output terminal of the conditioning circuit is connected to the microcontroller processing module; the conditioning circuit includes a frequency-to-voltage conversion chip, a comparator, and a first capacitor; the frequency-to-voltage conversion chip is connected in parallel with the first capacitor and is connected to the counter; the VOUT terminal of the frequency-to-voltage conversion chip is connected to the comparator.

2. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 1, characterized in that, The excitation conditioning module further includes an excitation signal generation circuit, which is electrically connected to the constant current source circuit. The excitation signal generation circuit includes an electromagnetic coil and an H-bridge chip connected to each other. The H-bridge chip is connected to a first, second, third, and fourth field-effect transistor. The H-bridge chip is also connected to the microcontroller processing module. The constant current source circuit includes a power supply chip, a first amplifier, a second amplifier, a voltage reference source, a first resistor, and a fifth field-effect transistor. The output terminal of the first amplifier is connected to the N1S / N2S terminal of the H-bridge chip, and the inverting input terminal is connected to the power supply chip. The non-inverting input terminal of the second amplifier is connected to the voltage reference source, the inverting input terminal is connected to the first resistor, and the output terminal is connected to the gate of the fifth field-effect transistor.

3. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 1, characterized in that, The signal amplification circuit includes a first-stage amplification circuit and a second-stage amplification circuit. The first-stage amplification circuit includes an instrumentation amplifier, a second resistor, and a third amplifier. The non-inverting and inverting input terminals of the instrumentation amplifier are both connected to the second resistor, and its output terminal is connected to the non-inverting input terminal of the third amplifier. The reference signal input terminal is connected to the signal filtering circuit. The second-stage amplification circuit includes a fourth amplifier, a fifth amplifier, and a third resistor. The output terminal of the fourth amplifier is connected to the inverting input terminal and the output terminal of the fifth amplifier. Its non-inverting input terminal is connected to the output terminal of the signal filtering circuit through the third resistor. The output terminal of the fifth amplifier is connected to the microcontroller processing module.

4. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 3, characterized in that, The signal filtering circuit includes an electrically connected RC low-pass filter circuit and an integral feedback circuit. The RC low-pass filter circuit includes a sixth amplifier, a fourth resistor, and a second capacitor. The non-inverting input terminal of the sixth amplifier is connected to the fourth resistor and the second capacitor, and its output terminal is connected to the non-inverting input terminal of the fourth amplifier through the third resistor. The integral feedback circuit includes a seventh amplifier, a fifth resistor, and a third capacitor. The signal output terminal of the seventh amplifier is connected to the reference signal input terminal of the instrumentation amplifier, and its inverting input terminal is connected to the signal output terminal of the instrumentation amplifier through the fifth resistor. Both the inverting input terminal and the output terminal are connected to the third capacitor.

5. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 4, characterized in that, The microcontroller processing module includes an MCU and an ADC converter. The MCU is electrically connected to the ADC converter. The PB3, PB4, PB5, and PB6 pins of the MCU are connected to the SCLK, CS#, DOUT, and DIN pins of the ADC converter, respectively. The signal input terminal of the ADC converter is connected to the output terminal of the fifth amplifier.

6. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 5, characterized in that, The control module also includes a human-machine interaction module electrically connected to the microcontroller processing module, the human-machine interaction module including buttons, a display and a memory chip; One end of the button is connected to the high level of the MCU, and the other end is connected to the IO port of the MCU and pulled down to ground; The display device includes a display screen and a display chip that are interconnected, and the display chip is connected to the PB12, PB13, PB15, PDS, PD9, PD10, PD11 and PD7 pins of the MCU; The WC#, SCL, and SDA pins of the memory chip are connected to the PE15, PB10, and PB11 pins of the MCU, respectively.

7. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 5, characterized in that, The control module further includes a communication output module electrically connected to the microcontroller processing module, the communication output module including a communication circuit and a current circuit; The communication circuit includes a communication chip. The three signal output terminals of the MCU are respectively connected to the receiver output terminal, driver input terminal and driver enable terminal of the communication chip through an optocoupler chip and a two-channel digital isolator. The receiver output enable terminal of the communication chip is connected to the driver enable terminal. The current circuit includes a current output chip. A pair of IIC signal ports of the MCU are connected to the IIC signal ports of the current output chip through an IIC digital isolator. The current output chip is also connected to the output of an eighth amplifier.

8. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 5, characterized in that, The control module further includes a power drive module electrically connected to the microcontroller processing module. The power drive module includes a power converter and a power supply unit electrically connected to each other. The power converter is connected to the MCU through a voltage conversion chip.

9. The electromagnetic flowmeter with an empty pipe detection circuit according to claim 2, characterized in that, It also includes electrodes and a sensor electrically connected to the control module. The control module, electromagnetic coil, sensor, and electrodes are connected to the pipe under test. The pipe under test includes a first pipe and a second pipe connected to each other. A connecting member is connected to each side of the first pipe. The electrodes are provided on both sides of the first pipe. The sensor is located between the two electrodes. The control module is provided on the second pipe.

Images