Low power excitation system and method for electromagnetic water meter and electromagnetic flowmeter

Abstract

The application discloses a low-power excitation system and method of an electromagnetic water meter and an electromagnetic flowmeter, which applies pre-excitation technology, and first applies a fast narrow pulse signal to a coil and a magnetic core for primary excitation, so as to prepare for reducing the coercive force of a magnetic field in secondary excitation; then, a wide pulse is applied for secondary excitation. The combined excitation mode can shorten the overall excitation time and reduce the influence of differential interference caused by rapid change of the magnetic field. In the method, the application also abandons the traditional constant-current and constant-voltage excitation technology, and instead fully utilizes the flow signal sensed by the coil and the magnetic core in the charging and discharging process, so that the excitation time of the wide pulse is significantly shortened, the overall operation power consumption is reduced, and the measurement accuracy problem caused by the change of the power supply voltage is overcome by combining the excitation power supply voltage compensation technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic water meters and electromagnetic flowmeters, and particularly relates to a low-power excitation system and method for an electromagnetic water meter and an electromagnetic flowmeter. BACKGROUND

[0002] The excitation power consumption of the coil and the magnetic core accounts for as high as 80% of the power consumption of the electromagnetic water meter and the electromagnetic flowmeter. When a disposable lithium battery is used for power supply, in order to ensure the service life, the excitation interval period is generally lengthened to reduce the power consumption, but this reduces the timeliness of flow measurement, especially when the flow is irregularly used and frequently turned on and off, which will cause a relatively large deviation in metering. Therefore, the frequency of the excitation coil and the magnetic core needs to be increased to obtain the flow signal.

[0003] Considering the energy consumption problem, increasing the excitation frequency means shortening the time of each excitation, but shortening the excitation time will introduce another problem, that is, the influence of differential interference on the flow. During the charging and discharging processes of the coil and the magnetic core, due to the sudden change of the current, a changing magnetic field will be generated around the coil and the magnetic core, which will be coupled through space to the loop composed of the two electrode signal lines, causing differential interference. The size of the differential interference is closely related to the speed of the change of the magnetic field.

[0004] In addition, the electromagnetic flowmeter and the electromagnetic water meter generally use a switch tube matched with a constant current tube or a DC / DC driving mode to excite the coil and the magnetic core. This mode has a problem of conversion efficiency. Energy is wasted on the constant current tube or the switching device of the DC / DC circuit.

[0005] For example, a Chinese patent with publication number CN211234567U relates to a low-power electromagnetic flowmeter with intelligent adjustment of excitation pulses. The variable sampling frequency is used to sample the excitation signals of the variable excitation current, the variable excitation pulse, the pulse interval and the pulse width, which can be intelligently adjusted. The signal sampling frequency can be intelligently adjusted according to the flow size and stability to realize high-precision measurement at small flow points and low power consumption of the system. However, the Chinese patent with publication number CN211234567U will produce differential interference when adjusting the pulse signal, affecting the measurement accuracy, and will also cause energy waste. SUMMARY

[0006] In order to reduce the power consumption of the electromagnetic water meter and the electromagnetic flowmeter while improving the measurement accuracy, the present application proposes a low-power excitation system and method for an electromagnetic water meter and an electromagnetic flowmeter. The pre-excitation technology and the excitation method combining narrow pulses and wide pulses are used to reduce the power consumption of the electromagnetic water meter and the electromagnetic flowmeter. The supply voltage and current of the excitation driving circuit are collected to compensate the flow signal and improve the measurement accuracy.

[0007] In order to achieve the above object, the application adopts the following technical scheme: a low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter, comprising a conduit and an excitation drive circuit connected with an electromagnetic element, the electromagnetic element generates a magnetic field inside the conduit, electrodes are respectively installed on the front and back sides of the conduit, the electrodes are connected with an instrument amplifier, the instrument amplifier is connected with a control module through an analog-to-digital conversion module, and the control module excites the electromagnetic element through combination of narrow pulses and wide pulses.

[0008] In the technical scheme, the excitation is performed through combination of narrow pulses and wide pulses, so that the rate of change of the magnetic field is reduced, the influence of differential interference is reduced, the excitation loss is reduced, and the flow measurement accuracy is improved. Under the same lithium battery capacity, the measurement period can be improved to 1 second / time, and the real-time performance and accuracy of flow measurement are effectively improved.

[0009] Preferably, the excitation drive circuit comprises an H-bridge composed of four switching tubes, the excitation branch and the freewheeling branch are connected between the power supply end and the ground end of the H-bridge, the excitation branch and the freewheeling branch are provided with switching tubes, the electromagnetic element is connected between the two output ports of the H-bridge, and the gates of the switching tubes receive control signals output by the control module; the H-bridge is composed of switching tubes Q11, Q12, Q13 and Q14, the excitation branch comprises switching tube Q15, the freewheeling branch comprises switching tube Q16, and control signals S11, S12, S13, S14, S15 and S16 control the switching states of Q11, Q12, Q13, Q14, Q15 and Q16, respectively, with high level being on and low level being off.

[0010] Preferably, the excitation branch comprises a battery, the negative electrode of the battery is connected to the ground end of the H-bridge, the positive electrode of the battery is connected to the source electrode of switching tube Q15, the drain electrode of switching tube Q15 is connected to the power supply end of the H-bridge, and switching tube Q15 is used for protecting the lithium battery and preventing the backflow of discharge current.

[0011] Preferably, the freewheeling branch comprises capacitor C11, the first end of capacitor C11 is connected to the ground end of the H-bridge, the second end of capacitor C11 is connected to the drain electrode of switching tube Q16, the source electrode of switching tube Q16 is connected to the power supply end of the H-bridge, switching tube Q16 and C11 constitute an energy recovery circuit for collecting the current when the coil discharges.

[0012] The application also adopts the following technical scheme: a low-power excitation method of an electromagnetic water meter and an electromagnetic flowmeter, which adopts the low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter described above, and is characterized in that the electromagnetic element is excited through combination of narrow pulses and wide pulses, the voltage response in the wide pulse excitation and subsequent discharge period is collected to obtain a flow signal, and the flow signal amplitude is proportional to the fluid flow.

[0013] Unlike the prior art method of waiting for the current of the excitation coil and the magnetic core to reach a constant value, ensuring that the magnetic field is stable before sampling the induced electromotive force generated thereby, the technical solution in this technical solution collects the flow signal generated by the coil and the magnetic core during the wide pulse excitation charging and discharging process, which not only offsets the influence of differential interference, but also further reduces the excitation time of the wide pulse, thereby reducing energy consumption.

[0014] Preferably, the combined excitation includes: first applying a narrow pulse for pre-excitation, and then applying a wide pulse for secondary excitation, and the pre-excitation utilizes the residual magnetism of the electromagnetic element to reduce the differential interference during the secondary excitation.

[0015] Preferably, the method comprises the following steps:

[0016] S1, pre-excitation is performed on the electromagnetic element by applying a narrow pulse with a time width of Ts, and a discharge circuit with a time width of Ts is provided for energy recovery;

[0017] S2, under the condition of the magnetic field after pre-excitation, secondary excitation is performed on the electromagnetic element by applying a wide pulse with a time width of Td in the same direction, a discharge circuit with a time width of Td is provided for secondary energy recovery, and Td≥Ts;

[0018] S3, the flow voltage signal during the secondary excitation and the secondary energy recovery time is collected.

[0019] Preferably, the step S3 comprises:

[0020] S31, the flow signal during the secondary excitation and the secondary energy recovery time is collected for arithmetic averaging to obtain the flow voltage signal, and the flow voltage signal is proportional to the liquid flow rate in the conduit;

[0021] S32, the actual voltage of the lithium battery under the secondary excitation is collected, the voltage compensation coefficient is calculated for voltage compensation of the flow voltage signal; and S33, the excitation current flowing through the electromagnetic element is collected, the current compensation coefficient is calculated for current compensation of the flow voltage signal.

[0022] Preferably, the step S32 comprises:

[0023] S321, the lithium battery voltage during the secondary excitation time is collected, a preset standard voltage value is divided by the real-time collected value to obtain the voltage compensation coefficient;

[0024] S322, the voltage compensation coefficient is multiplied by the flow voltage signal to dynamically adjust and compensate the flow measurement error caused by the drop of the lithium battery voltage.

[0025] Preferably, the step S33 comprises:

[0026] S331, collect the excitation current flowing through the electromagnetic element during the secondary excitation and secondary energy recovery time, divide the excitation current at the factory by the excitation current to obtain a current compensation coefficient;

[0027] S332, multiply the current compensation coefficient by the flow voltage signal to compensate for the measurement error caused by the external magnetic field.

[0028] The beneficial effects of the present application are:

[0029] 1) using narrow pulses for pre-excitation, and then using wider pulses for excitation, reducing the rate of change of the magnetic field, reducing the influence of differential interference, and reducing excitation loss;

[0030] 2) collecting the flow signal generated by the coil and magnetic core during the wide pulse excitation charging and discharging process, which not only offsets the influence of differential interference, but also further reduces the excitation time of the wide pulse, thereby reducing energy consumption;

[0031] 3) using lithium batteries for direct power supply, and using H-bridge to excite the coil and magnetic core, and using excitation voltage sampling compensation technology to simplify the circuit, reduce loss and improve measurement accuracy;

[0032] 4) Through the automatic enhancement mechanism of excitation current, the magnetic field strength generated by the internal magnetic coil and magnetic core is improved, thereby effectively compensating the potential interference of the external static magnetic field on the flowmeter measurement accuracy, achieving dynamic balance and precise correction of the influence of the static magnetic field. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a functional block diagram of a low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter of the present application.

[0034] Figure 2 is a schematic diagram of the excitation circuit of the forward excitation drive of the low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the present application.

[0035] Figure 3 is a schematic diagram of the excitation circuit of the forward excitation drive of the low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the present application.

[0036] Figure 4 is a schematic diagram of the discharge circuit of the reverse excitation drive of the low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the present application.

[0037] Figure 5 is a schematic diagram of the excitation branch of the reverse excitation drive of the low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the present application.

[0038] Figure 6 is a schematic diagram of the discharge circuit of the reverse excitation drive of the low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the present application.

[0039] Figure 7 is the timing diagram of the wide and narrow pulse forward excitation control of the present application.

[0040] Figure 8 is the timing diagram of the wide and narrow pulse reverse excitation control of the present application.

[0041] Figure 9 is the timing diagram of the wide and narrow pulse forward excitation flow acquisition of the present application.

[0042] Figure 10 is the timing diagram of the wide and narrow pulse reverse excitation flow acquisition of the present application.

[0043] Figure 11 is the schematic diagram of the forward excitation differential interference of the present application.

[0044] Figure 12 is the schematic diagram of the reverse excitation differential interference of the present application.

[0045] Figure 13 is the schematic diagram of the magnetic field change rate of the present application.

[0046] Figure 14 is the timing diagram of the embodiment 5 of the present application.

[0047] Figure 15 is the timing diagram of the embodiment 6 of the present application.

[0048] Figure 16 is the timing diagram of the embodiment 7 of the present application.

[0049] Figure 17 is the timing diagram of the embodiment 8 of the present application.

[0050] Figure 18 is the timing diagram of the embodiment 9 of the present application.

[0051] Figure 19 is the timing diagram of the embodiment 10 of the present application.

[0052] Reference signs: excitation drive circuit 10; electromagnetic element L11; excitation current I L ; internal diode D16 of switch tube Q16; conduit 20; electrode positive pole 21a; electrode negative pole 21b; instrument amplifier 30; analog-to-digital conversion module 40; control module 50; first pulse width T s ; second pulse width T d ; differential interference DI; first slope K1; second slope K2; first magnetic field strength B0; second magnetic field strength B r ; third magnetic field strength B s . DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific implementation described herein is only one of the best embodiments of the present application, which is used to explain the present application and does not limit the protection scope of the present application. All other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0054] Example 1

[0055] The present embodiment provides a low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter, which refers to Figure 1 , comprising an excitation driving circuit 10, an electromagnetic element L11, a conduit 20, an electrode 21, an instrument amplifier 30, an analog-digital conversion module 40 and a control module 50.

[0056] The output port of the excitation driving circuit is connected to the electromagnetic element, which is arranged near the conduit.

[0057] In the present embodiment, the electromagnetic element is composed of a coil and a magnetic core. The excitation driving circuit applies the voltage of a lithium battery to both ends of the coil. After current passes through the coil, a magnetic field is generated inside the conduit.

[0058] The electrode is installed on the front and back sides of the conduit respectively. The electrode picks up the voltage signal generated by cutting the magnetic force lines of the conductive liquid flowing in the pipeline, which is proportional to the flow size.

[0059] The electrode is connected to the instrument amplifier. The instrument amplifier differentially amplifies the voltage on the two electrodes, overcomes common-mode interference and realizes impedance conversion.

[0060] The instrument amplifier is connected to the control module through the analog-digital conversion module. The analog-digital conversion module converts the signal after the instrument amplifier into a digital signal. The control module can excite the electromagnetic element by combining narrow pulses and wide pulses.

[0061] In the present embodiment, the control module includes a single-chip microcomputer and a timer. On the one hand, the timer generates wide and narrow pulse to drive the excitation driving circuit. On the other hand, the control module controls the analog-digital conversion module to perform specific algebraic operations on the obtained digital signal to obtain the final flow value.

[0062] The excitation circuit is composed of a lithium battery, switching tubes Q11, Q12, Q13, Q14, Q15, Q16 and a capacitor C11. The switching tube is a switching semiconductor device. In the present embodiment, the switching tubes Q11, Q12, Q13, Q14, Q15 and Q16 are all N-channel MOS tubes.

[0063] As Figure 2As shown, MOS tube Q11, MOS tube Q12, MOS tube Q13 and MOS tube Q14 constitute an H bridge, and the electromagnetic element is connected between the two output ports of the H bridge.

[0064] Two branches are connected between the power terminal and the ground terminal of the H bridge, which are an excitation branch and a freewheeling branch, and the excitation branch and the freewheeling branch are each provided with a switch tube.

[0065] Specifically, the excitation branch includes a battery and a MOS tube Q15, the negative electrode of the battery is connected to the ground terminal of the H bridge, the positive electrode of the battery is connected to the source electrode of the MOS tube Q15, and the drain electrode of the MOS tube Q15 is connected to the power terminal of the H bridge.

[0066] Among them, the MOS tube Q15 is used to protect the lithium battery and prevent the discharge current from flowing back.

[0067] The freewheeling branch includes a capacitor C11 and a MOS tube Q16, the first end of the capacitor C11 is connected to the ground terminal of the H bridge, the second end of the capacitor C11 is connected to the drain electrode of the switch tube Q16, and the source electrode of the switch tube Q16 is connected to the power terminal of the H bridge.

[0068] Among them, the MOS tube Q16 and the C11 constitute an energy recovery circuit for collecting the current when the coil discharges.

[0069] The gate electrodes of all the switch tubes of the excitation drive circuit are connected to the control module and receive control signals from the control module.

[0070] The control signals S11, S12, S13, S14, S15 and S16 control the switching states of Q11, Q12, Q13, Q14, Q15 and Q16 respectively, the high level is on, and the low level is off, and the control signals generated by the control module provide the electromagnetic element with an excitation circuit without conversion loss and a freewheeling circuit with low impedance.

[0071] When the current flows through the electromagnetic element L11, a magnetic field environment will be induced in the internal conduit area. At this time, if there is a conductive liquid flowing in the conduit, the liquid will cut the magnetic field, thereby inducing a voltage signal at the two electrodes.

[0072] It is worth noting that the strength of this voltage signal is directly proportional to the flow rate of the conductive liquid, and this characteristic provides a basis for flow measurement.

[0073] In addition, due to the inherent properties of the magnetic core material, after the excitation current is zero, a certain amount of residual magnetism will be maintained in the magnetic core for a short time. This residual magnetism phenomenon is ingeniously utilized in the present application to optimize the subsequent measurement process.

[0074] Specifically, the application first uses a narrow pulse for pre-excitation, and uses the residual magnetism in the magnetic core after the process as the starting magnetic field condition for the secondary wide pulse excitation.

[0075] Compared with the wide pulse excitation starting from zero magnetic field, the starting condition based on residual magnetism significantly reduces the differential interference generated by L11 in the secondary excitation process.

[0076] The size of the differential interference is usually closely related to the magnetic field change rate, and the presence of residual magnetism effectively reduces the degree of change of the magnetic field from zero, thereby realizing the reduction of the differential interference.

[0077] In summary, by introducing narrow pulse pre-excitation and using the residual magnetism generated thereby, the application successfully reduces the differential interference in the secondary wide pulse excitation, thereby improving the accuracy of flow measurement.

[0078] The low-power excitation system of the electromagnetic water meter and the electromagnetic flowmeter of the embodiment adopts an excitation method combining narrow pulses and wide pulses, and the current flowing from the left side of the electromagnetic element L11 to the right side thereof is defined as positive, and the current flowing from the right side of the electromagnetic element L11 to the left side thereof is defined as negative.

[0079] The application first excites the electromagnetic element L11 by a narrow pulse with a time width Ts, then provides a low-impedance discharge circuit for the electromagnetic element L11, and then excites the electromagnetic element L11 by a wide pulse with a time width Td in the same direction, and then provides a low-impedance discharge circuit for the electromagnetic element L11.

[0080] For positive excitation driving, Q11, Q14, and Q15 are opened, and Q12, Q13, and Q16 are closed, at this time, the current flows from the positive terminal of the lithium battery, flows through Q15, Q11, the coil L11, Q14, and then flows back to the ground terminal.

[0081] For the discharge circuit after positive excitation, Q11, Q14, and Q15 are closed, and Q12, Q13, and Q16 are opened, at this time, the current is pulled out from the ground terminal, and sequentially charges C11 capacitor through Q12, Q13, and Q16, this process can be understood as energy recovery.

[0082] The current is pulled out from the ground terminal, and sequentially flows through the diodes inside Q12, Q13, and Q16, this mode obviously increases the loss of the diodes inside the switch tube, and increases the burden of the low-power system compared with the control mode of the application.

[0083] For reverse excitation drive, by opening Q12, Q13, Q15, Q16, closing Q11, Q14, at this time the current from the positive end of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground.

[0084] For the discharge circuit after reverse excitation, by closing Q12, Q13, Q15, opening Q11, Q14, Q16, at this time the current is pulled out from the ground, sequentially through Q11, Q14, Q16, charging C11 capacitor, this process can be understood as energy recovery.

[0085] As the discharge control mode after forward excitation, this mode can effectively reduce the loss of the internal diode of the switch tube, and reduce the burden of the low-power system.

[0086] It should be noted that the main difference between the wide pulse and the narrow pulse mentioned in the application is the pulse width, and the width of the narrow pulse is less than or equal to the width of the wide pulse.

[0087] The wide pulse and the narrow pulse generated by the application are applied to the two ends of the coil, and the excitation of the forward wide pulse or the narrow pulse and the reverse wide pulse or the narrow pulse is realized by controlling the switch tube.

[0088] Embodiment 2

[0089] The embodiment provides a low-power excitation method of an electromagnetic water meter and an electromagnetic flowmeter, which combines the wide pulse and the narrow pulse generated above, and innovatively proposes a pre-excitation coil driving mode, specifically including the following steps: first, applying a narrow pulse Ts to the coil, then providing a discharge circuit with a time width of Ts to provide a freewheeling circuit for the current on the coil after narrow pulse excitation; then, applying a wide pulse Td to the coil again, and then providing a discharge circuit with a time width of Td to provide a freewheeling circuit for the current on the coil after wide pulse excitation.

[0090] This excitation mode can effectively reduce the coercive force of the coil. According to the low-power excitation method of the electromagnetic water meter and the electromagnetic flowmeter, the narrow pulse excitation enters the discharge circuit for energy recovery immediately, but due to the action of the magnetic hysteresis return curve of the electromagnetic element L11, the electromagnetic element L11 still has a magnetic field strength Br after discharge, and when the same direction wide pulse excitation is performed, the electromagnetic element L11 can reach the magnetic field strength Bs more quickly.

[0091] Through this mode, on the one hand, the peak value of the differential interference coupled to the signal end due to the change of the magnetic field can be effectively reduced, and on the other hand, due to the existence of the discharge circuits with widths of Ts and Td, flow signals will also be generated in these circuits, and by picking up part of the flow signals, not only the differential interference can be offset, but also the acquisition period of the flow signals can be prolonged, and the stability of the flow signal acquisition can be improved.

[0092] In addition, the wide and narrow pulse combination can reduce the differential interference. Figure 13 As shown in the figure, when the narrow pulse initially excites the electromagnetic element L11, the initial value of the magnetic field on the electromagnetic element L11 is 0, and the rising slope during the excitation is the highest, K1>K2.

[0093] The differential interference peak value coupled to the signal is high, and if the peak voltage is collected into the flow calculation, it will have a great influence on the accuracy. Although a patent discloses that the differential interference corresponding to the discharge circuit can be compensated, but this method cannot completely overcome.

[0094] And the method of the application, after the narrow pulse excitation, followed by a wide pulse in the same direction, can reduce the slope of the magnetic field change and reduce the peak value of the differential interference, as shown in the figure. Figure 12 In addition, by collecting the differential interference signal generated by the discharge circuit after the wide pulse excitation, the differential interference generated by the wide pulse excitation can be effectively offset.

[0095] The application collects the flow signal corresponding to the wide pulse excitation and the discharge circuit time following it, and accumulates all the voltage values collected to obtain a voltage value proportional to the flow rate through the pipeline.

[0096] As shown in the flow collection area of the figure, the voltage value collected by the application is significantly different from the prior art. Figure 12 First, since the narrow pulse excitation is followed by wide pulse excitation, the differential interference generated during the wide pulse excitation is smaller.

[0097] Second, the collection period is 2*Td time, and this collection method can basically completely overcome the influence of differential interference. The differential interference generated by the wide pulse excitation and the differential interference generated by the discharge circuit following it can offset each other.

[0098] Third, the 2*Td time is controlled between 10ms-40ms, and the wide pulse is set because enough time is needed for analog-to-digital conversion. Because the length of the collection time affects the stability of the digital signal, longer collection time can overcome the influence of the thermal noise generated by the amplification circuit, and can also overcome the influence of the power frequency. If the collection frequency of 10Khz is matched, then there are 100-400 AD values in the corresponding time.

[0099]

[0100] ​After the wide and narrow pulse excitation, the application provides a specific discharge circuit, which is used for energy recovery on one hand and picking up the differential interference and flow signal on the other hand. The energy recovery is realized through the capacitor C11, and the differential interference is used for compensating the differential interference generated in the wide pulse excitation. The direction of the current in the coil of the electromagnetic element L11 does not change in the discharge time, only the current value is slowly reduced. The application also focuses on the induced electromotive force generated between the electrodes in this time, and the sampling number is increased and the excitation time of the wide pulse is shortened by picking up the electromotive force.

[0101] Embodiment 3

[0102] The embodiment takes the forward excitation as an example to further illustrate the low-power excitation method of the electromagnetic water meter and the electromagnetic flowmeter.

[0103] Q11, Q14, Q15 and Q16 are opened, and Q12 and Q13 are closed. At this time, the current is started from the positive terminal of the lithium battery, flows through Q15, Q11, the coil L11, Q14, and then flows back to the ground terminal, and the duration width is Ts.

[0104] Q11, Q14 and Q15 are closed, and Q12, Q13 and Q16 are opened. At this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13 and Q16, and charges the C11 capacitor. The duration is Ts.

[0105] Q11, Q14, Q15 and Q16 are opened, and Q12 and Q13 are closed. At this time, the current is started from the positive terminal of the lithium battery, flows through Q15, Q11, the coil L11, Q14, and then flows back to the ground terminal, and the duration width is Td.

[0106] Q11, Q14 and Q15 are closed, and Q12, Q13 and Q16 are opened. At this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13 and Q16, and charges the C11 capacitor. The duration is Td.

[0107] The flow signal collection time is shown in Figure 9 The voltage value obtained by the arithmetic average of the collected signals is proportional to the flow rate through the pipeline.

[0108] Embodiment 4

[0109] The embodiment takes the reverse excitation as an example to further illustrate the low-power excitation method of the electromagnetic water meter and the electromagnetic flowmeter.

[0110] The main difference between the embodiment and embodiment 3 is that the reverse excitation mode is adopted.

[0111] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time, the current is from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Ts.

[0112] Close Q12, Q13, Q15, open Q11, Q14, Q16, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Ts.

[0113] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time, the current is from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Td.

[0114] Close Q12, Q13, Q15, open Q11, Q14, Q16, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Td.

[0115] The flow signal collection time is shown in Table 1. Figure 10 The voltage value obtained by performing arithmetic averaging on the collected signals is proportional to the flow rate through the pipeline.

[0116] Example 5

[0117] This embodiment takes forward excitation + reverse excitation as an example to further illustrate the low-power excitation method of the electromagnetic water meter and the electromagnetic flowmeter. The combination of forward pulse and reverse pulse can prevent the electrode of the electromagnetic water meter or the electromagnetic flowmeter from being polarized under the same direction pulse excitation, and can overcome the influence of power frequency according to the same phase sampling technology.

[0118] Open Q11, Q14, Q15, Q16, close Q12, Q13, at this time, the current is from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Ts; close Q11, Q14, Q15, open Q12, Q13, Q16, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Ts.

[0119] Open Q11, Q14, Q15, Q16, close Q12, Q13, at this time, the current is from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Td; close Q11, Q14, Q15, open Q12, Q13, Q16, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Td.

[0120] Q12, Q13, Q15, Q16 are opened, Q11, Q14 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Ts; Q12, Q13, Q15 are closed, Q11, Q14, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Ts.

[0121] Q12, Q13, Q15, Q16 are opened, Q11, Q14 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Td; Q12, Q13, Q15 are closed, Q11, Q14, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Td.

[0122] The flow signal collection time is shown in Table 1 Figure 14 The voltage signal proportional to the flow rate can also be obtained by subtracting the voltage value obtained by arithmetically averaging the signals corresponding to the forward excitation signals from the voltage value obtained by arithmetically averaging the signals corresponding to the reverse excitation signals.

[0123] Embodiment 6

[0124] This embodiment takes reverse excitation + forward excitation as an example to further illustrate the low-power excitation method of the electromagnetic water meter and the electromagnetic flowmeter of the application. The main difference of this embodiment from embodiment 5 is that the coil is first excited by reverse wide and narrow pulses, and then excited by forward wide and narrow pulses.

[0125] Q12, Q13, Q15, Q16 are opened, Q11, Q14 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Ts; Q12, Q13, Q15 are closed, Q11, Q14, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Ts.

[0126] Q12, Q13, Q15, Q16 are opened, Q11, Q14 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Td; Q12, Q13, Q15 are closed, Q11, Q14, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Td.

[0127] Open Q11, Q14, Q15, Q16, close Q12, Q13, at this time the current from the positive terminal of lithium battery, through Q15, Q11, coil L11, Q14, and then flow back to the ground terminal, the duration width is Ts; close Q11, Q14, Q15, open Q12, Q13, Q16, at this time the current from the ground terminal, through Q12, Q13, Q16 in turn, charge C11 capacitor, the duration is Ts.

[0128] Open Q11, Q14, Q15, Q16, close Q12, Q13, at this time the current from the positive terminal of lithium battery, through Q15, Q11, coil L11, Q14, and then flow back to the ground terminal, the duration width is Td; close Q11, Q14, Q15, open Q12, Q13, Q16, at this time the current from the ground terminal, through Q12, Q13, Q16 in turn, charge C11 capacitor, the duration is Td.

[0129] Flow signal acquisition time is shown in Figure 15 The voltage signal proportional to the flow rate can also be obtained by subtracting the voltage value obtained by arithmetically averaging the signals corresponding to the reverse excitation signals from the voltage value obtained by arithmetically averaging the signals corresponding to the forward excitation signals.

[0130] Example 7

[0131] This embodiment takes forward excitation + reverse excitation + reverse excitation + forward excitation as an example to further illustrate a low-power excitation method of an electromagnetic water meter and an electromagnetic flowmeter of the application. This embodiment combines example 5 and example 6, and this combination is particularly suitable for scenarios that need to overcome the influence of DC drift under low power consumption.

[0132] The control feature of this mode is to first perform forward wide / narrow pulse excitation and reverse wide / narrow pulse excitation on the coil, then perform reverse wide / narrow pulse excitation and forward wide / narrow pulse excitation on the coil after a certain time interval, and perform arithmetical averaging and linear operation on the voltage values under wide pulse excitation to obtain a flow value that can overcome the DC drift. The specific operation steps are as follows.

[0133] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the positive terminal of lithium battery, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration width is Ts; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, through Q11, Q14, Q16 in turn, charge C11 capacitor, the duration is Ts.

[0134] Q12, Q13, Q15, Q16 are opened, Q11, Q14 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal, and the duration width is Td; Q12, Q13, Q15 are closed, Q11, Q14, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q11, Q14, Q16, and charges the C11 capacitor, and the duration is Td,

[0135] Q11, Q14, Q15, Q16 are opened, Q12, Q13 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Ts; Q11, Q14, Q15 are closed, Q12, Q13, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Ts.

[0136] Q11, Q14, Q15, Q16 are opened, Q12, Q13 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Td; Q11, Q14, Q15 are closed, Q12, Q13, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Td.

[0137] Q11, Q14, Q15, Q16 are opened, Q12, Q13 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Ts; Q11, Q14, Q15 are closed, Q12, Q13, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Ts.

[0138] Q11, Q14, Q15, Q16 are opened, Q12, Q13 are closed, at this time, the current flows from the positive terminal of the lithium battery, through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal, and the duration width is Td; Q11, Q14, Q15 are closed, Q12, Q13, Q16 are opened, at this time, the current is pulled out from the ground terminal, sequentially passes through Q12, Q13, Q16, and charges the C11 capacitor, and the duration is Td,

[0139] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the lithium battery positive terminal, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration of the width of Ts; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, through Q11, Q14, Q16, C11 capacitor charging, the duration of Ts.

[0140] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the lithium battery positive terminal, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration of the width of Td; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, through Q11, Q14, Q16, C11 capacitor charging, the duration of Td.

[0141] Flow signal acquisition time is seen Figure 16 , respectively, the corresponding signal of the two forward and reverse excitation signal addition operation, and then the arithmetic average voltage value of two forward excitation and two reverse excitation difference, can get rid of the DC drift voltage signal, the voltage signal is proportional to the flow rate.

[0142] Example 8

[0143] This embodiment with multiple narrow pulse + wide pulse as an example, to further illustrate the low power consumption of a kind of electromagnetic water meter and electromagnetic flowmeter excitation method of the present application. This embodiment uses a combination of multiple narrow pulse and single wide pulse, in the actual implementation of the above scheme, because the driven electromagnetic element L11 inductance is very different, especially in the drive inductance of the larger load, may need multiple narrow pulse excitation to reduce the influence of differential interference. The specific operation steps are as follows.

[0144] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the lithium battery positive terminal, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration of the width of Ts; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, through Q11, Q14, Q16, C11 capacitor charging, the duration of Ts.

[0145] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the lithium battery positive terminal, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration of the width of Ts; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, in turn through Q11, Q14, Q16, C11 capacitor charging, the duration of Ts.

[0146] Open Q12, Q13, Q15, Q16, close Q11, Q14, at this time the current from the lithium battery positive terminal, through Q15, Q12, coil L11, Q13, and then flow back to the ground terminal, the duration of the width of Td; close Q12, Q13, Q15, open Q11, Q14, Q16, at this time the current from the ground terminal, in turn through Q11, Q14, Q16, C11 capacitor charging, the duration of Td.

[0147] Flow signal acquisition time Figure 17 , by the arithmetic mean of the signal obtained by collecting the voltage value is proportional to the flow rate through the pipeline.

[0148] It should be noted that the wide pulse and narrow pulse combination excitation, in actual implementation, we can use a variety of ways, including but not limited to: positive narrow pulse + positive narrow pulse discharge + positive wide pulse + positive wide pulse discharge; negative narrow pulse + negative narrow pulse discharge + negative wide pulse + negative wide pulse discharge; positive narrow pulse + positive narrow pulse discharge + positive wide pulse + positive wide pulse discharge + negative narrow pulse + negative narrow pulse discharge + negative wide pulse + negative wide pulse discharge; negative narrow pulse + negative narrow pulse discharge + negative wide pulse + negative wide pulse discharge + positive narrow pulse + positive narrow pulse discharge + positive wide pulse + positive wide pulse discharge.

[0149] The above examples, although only a few representative way, but as long as the excitation mode based on wide narrow pulse should belong to the scope of protection of the present invention, and according to the size of the excited electromagnetic element L11 inductance, the wide pulse width Td can not be less than the narrow pulse width Ts, that is, Td ≥ Ts.

[0150] Example 9

[0151] The embodiment proposes a voltage compensation method in a low power excitation method of electromagnetic water meter and electromagnetic flowmeter, which can compensate the measurement error caused by the decrease of lithium battery voltage.

[0152] The application adopts a simple way, and a constant current source is not used in the circuit, but the voltage of the lithium battery is simply applied. The measurement error caused by the change of the lithium battery voltage exists, and therefore, during the coil excitation, the voltage across the lithium battery is collected for compensation. The voltage value obtained during the factory delivery is divided by the collected voltage value to obtain a voltage compensation coefficient for flow calculation. The specific calculation method is described below.

[0153] When the lithium battery supply voltage is insufficient, the lithium battery voltage V BATT-R is collected, and the collection timing is shown in Figure 18 . The obtained voltage value is compared with the lithium battery voltage V BATT-P during the factory delivery to obtain a voltage compensation coefficient . The voltage compensation coefficient is multiplied by the collected flow voltage signal to compensate for the measurement error caused by the decrease of the voltage.

[0154] Embodiment 10

[0155] The embodiment provides a current compensation method in a low-power excitation method of an electromagnetic water meter and an electromagnetic flowmeter, which is used for compensating the influence of an external static magnetic field on the electromagnetic water meter or the electromagnetic flowmeter.

[0156] When the external static magnetic field is close, the coil drive circuit of the application does not use a constant current sampling method. When the external magnetic field is close to the electromagnetic water meter or the electromagnetic flowmeter, the excitation current will increase under the influence of the external magnetic field, and the flow signal will decrease.

[0157] Although the increased excitation current has compensated for part of the influence of the external magnetic field, the application also compensates by collecting the current flowing through the coil. The coefficient obtained by dividing the decreased excitation current by the factory excitation current compensates the flow value, which can overcome the influence of the external static magnetic field during the use of the electromagnetic water meter or the electromagnetic flowmeter. The specific calculation method is described below.

[0158] The excitation current I R flowing through the coil is collected, and the collection timing is shown in Figure 18 . The collected current value is compared with the excitation current I P during the factory delivery to obtain a current compensation coefficient . The current compensation coefficient is multiplied by the collected flow voltage signal to compensate for the measurement error caused by the external magnetic field.

[0159] In the problem of dealing with the static magnetic field interference, unlike the magnetic shielding technology used in the prior art, when the external static magnetic field is close to the electromagnetic water meter or the electromagnetic flowmeter, the excitation drive circuit of the application can exhibit unique adaptability.

[0160] Specifically, the approximation of the external static magnetic field leads to a natural attenuation of the internal magnetic field, but this change not only does not cause adverse effects, but also triggers an automatic enhancement mechanism of the excitation current. This mechanism skillfully enhances the magnetic field strength generated by the internal magnetic coil and magnetic core, effectively compensating for the potential interference of the external static magnetic field on the flowmeter measurement accuracy, achieving dynamic balance and precise correction of the influence of the static magnetic field.

Claims

1. A low power consumption excitation method for electromagnetic water meters and electromagnetic flowmeters, characterized by, The narrow pulse and the wide pulse are combined to excite the electromagnetic element, and the voltage response in the wide pulse excitation and the subsequent discharge period is collected to obtain the flow signal, the amplitude of which is proportional to the fluid flow, comprising the following steps: S1, pre-excitation is performed on the electromagnetic element by applying a narrow pulse with a time width of Ts, and an energy recovery circuit with a time width of Ts is provided; S2, under the condition of the magnetic field after pre-excitation, the electromagnetic element is excited again by applying a wide pulse with a time width of Td in the same direction, and a discharge circuit with a time width of Td is provided for secondary energy recovery, Td≥Ts; S3, collecting the flow voltage signal in the secondary excitation and secondary energy recovery time.

2. The low power consumption excitation method of electromagnetic water meter and electromagnetic flowmeter according to claim 1, characterized in that, The combined excitation includes: first applying a narrow pulse for pre-excitation, and then applying a wide pulse for secondary excitation, and the pre-excitation utilizes the residual magnetism of the electromagnetic element to reduce the differential interference during the secondary excitation.

3. The low power excitation method of electromagnetic water meter and electromagnetic flowmeter according to claim 2, characterized in that, The step S3 comprises: S31, collecting the flow signal in the secondary excitation and secondary energy recovery time to obtain the flow voltage signal, which is proportional to the liquid flow rate in the conduit; S32, collecting the actual voltage of the lithium battery under the secondary excitation, calculating the voltage compensation coefficient, and compensating the flow voltage signal; S33, collecting the excitation current flowing through the electromagnetic element, calculating the current compensation coefficient, and compensating the flow voltage signal.

4. The low power excitation method of electromagnetic water meter and electromagnetic flowmeter according to claim 3, characterized in that, The step S32 comprises: S321, collect the lithium battery voltage V in the secondary excitation time BATT-R , the preset standard voltage value V BATT-P is divided by the real-time collected V BATT-R , the voltage compensation coefficient is obtained; S322, multiplying the voltage compensation coefficient by the flow voltage signal to dynamically adjust and compensate the flow measurement error caused by the voltage drop of the lithium battery.

5. The low power excitation method of electromagnetic water meter and electromagnetic flowmeter according to claim 3, characterized in that, The step S33 comprises: S331, collects the excitation current I flowing through the electromagnetic element during the secondary excitation and secondary energy recovery time. R I R Compared with the excitation current I at the factory P The current compensation coefficient is obtained by dividing the phases. S332, multiplying the current compensation coefficient by the flow voltage signal to compensate the measurement error caused by the external magnetic field.

6. A low power consumption excitation system of electromagnetic water meter and electromagnetic flowmeter, realizing the low power consumption excitation method of electromagnetic water meter and electromagnetic flowmeter in any one of claims 1-5, characterized in that, The conduit and the excitation driving circuit connected with the electromagnetic element are provided, the electromagnetic element generates a magnetic field inside the conduit, electrodes are respectively installed on the front and back sides of the conduit, the electrodes are connected with an instrument amplifier, the instrument amplifier is connected with a control module through an analog-to-digital conversion module, and the control module combines narrow pulses and wide pulses to excite the electromagnetic element.

7. A low power consumption excitation system for electromagnetic water meters and electromagnetic flow meters according to claim 6, characterized in that The excitation driving circuit comprises an H-bridge composed of four switching tubes, an excitation branch and a freewheeling branch are connected between the power supply end and the ground end of the H-bridge, the excitation branch and the freewheeling branch are provided with switching tubes, the electromagnetic element is connected between the two output ports of the H-bridge, and the gates of the switching tubes receive control signals output by the control module.

8. A low power consumption excitation system for electromagnetic water meters and electromagnetic flow meters according to claim 7, characterized in that, The excitation branch comprises a battery, the negative electrode of the battery is connected with the ground end of the H-bridge, the positive electrode of the battery is connected with the source electrode of the switching tube Q15, and the drain electrode of the switching tube Q15 is connected with the power supply end of the H-bridge.

9. A low power consumption excitation system for electromagnetic water meters and electromagnetic flow meters according to claim 7 or 8, characterized in that, The freewheeling branch comprises a capacitor C11, the first end of the capacitor C11 is connected with the ground end of the H-bridge, the second end of the capacitor C11 is connected with the drain electrode of the switching tube Q16, and the source electrode of the switching tube Q16 is connected with the power supply end of the H-bridge.

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