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

Abstract

According to the low-power-consumption excitation system and method for the electromagnetic water meter and the electromagnetic flowmeter, a pre-excitation technology is applied, firstly, a rapid narrow pulse signal is applied to a coil and a magnetic core for primary excitation, and preparation is made for reducing the coercive force of a magnetic field during secondary excitation; and then wide pulse is applied to carry out secondary excitation. According to the combined excitation mode, on one hand, the overall excitation time can be shortened, and on the other hand, the influence of differential interference generated by rapid change of a magnetic field is reduced. In the method, the traditional excitation constant-current and constant-voltage technology is abandoned, flow signals induced by the coil and the magnetic core in the charging and discharging process are fully utilized, the excitation time of the wide pulse is remarkably shortened, the overall operation power consumption is reduced, and meanwhile, the excitation power supply voltage compensation technology is combined, so that the energy consumption is reduced. And the problem of measurement precision caused by power supply voltage change is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic water meters and electromagnetic flow meters, and particularly relates to a low-power excitation system and method for an electromagnetic water meter and an electromagnetic flow meter. Background Art

[0002] The excitation power consumption of the coil and the magnetic core accounts for up to 80% of the power consumption of the electromagnetic water meter and the electromagnetic flow meter. When a disposable lithium battery is used for power supply, in order to ensure the service life, the excitation interval period is generally extended to reduce the power consumption. However, this reduces the timeliness of flow measurement. Especially when the flow usage is irregular and the flow is frequently switched on and off, this will cause a relatively large deviation in measurement. Therefore, it is necessary to increase the frequency of the excitation coil and the magnetic core to obtain the flow signal.

[0003] Considering the energy consumption problem, increasing the excitation frequency means shortening the time of each excitation. However, 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. This magnetic field will be coupled to the loop composed of two electrode signal lines through space, causing differential interference. The magnitude of the differential interference is closely related to the speed of the magnetic field change.

[0004] In addition, the excitation of the coil and the magnetic core in the electromagnetic flow meter and the electromagnetic water meter generally adopts a switching tube supporting a constant current tube or a DC / DC driving method. This method has a problem of conversion efficiency, and energy will be lost on the constant current tube or the switching device of the DC / DC circuit, resulting in energy waste.

[0005] For example, there is a Chinese patent with the publication number CN211234567U, which relates to a low-power electromagnetic flow meter with intelligent adjustment of excitation pulses. It adopts a variable sampling frequency and can sample the excitation signal with variable excitation current, variable excitation pulse, pulse interval and pulse width that can be intelligently adjusted. The signal sampling frequency can be intelligently adjusted according to the flow rate and stability to achieve high-precision measurement at small flow rate points and low power consumption of the system. However, the Chinese patent with the publication number CN211234567U will generate differential interference when adjusting the pulse signal, affecting the measurement accuracy, and on the other hand, it will cause energy waste. Summary of the Invention

[0006] In order to reduce the power consumption of the electromagnetic water meter and the electromagnetic flow meter while improving the measurement accuracy, the present invention proposes a low-power excitation system and method for an electromagnetic water meter and an electromagnetic flow meter. By means of pre-excitation technology and an excitation method combining narrow pulses and wide pulses, the power consumption of the electromagnetic water meter and the electromagnetic flow meter is reduced, and the flow signal is compensated by collecting the supply voltage and current of the excitation drive circuit to improve the measurement accuracy.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter, including 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 rear sides of the conduit. The electrodes are connected with an instrumentation amplifier. The instrumentation amplifier is connected with a control module through an analog-to-digital conversion module. The control module excites the electromagnetic element through a combination of narrow pulses and wide pulses.

[0008] In this technical solution, pre-excitation is carried out by using narrow pulses, and then wider pulses are used for excitation, reducing the rate of magnetic field change, minimizing the influence of differential interference, reducing excitation loss and improving the flow measurement accuracy. With the same lithium battery capacity, the measurement period can be increased to 1 second / time, effectively improving the real-time performance and accuracy of flow measurement.

[0009] Preferably, the excitation drive circuit includes an H-bridge composed of four switching tubes. An excitation branch and a freewheeling branch are connected between the power supply terminal and the ground terminal 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. 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, Q14. The excitation branch includes switching tube Q15, and the freewheeling branch includes switching tube Q16. Control signals S11, S12, S13, S14, S15, S16 respectively control the switching states of Q11, Q12, Q13, Q14, Q15, Q16. High level is conduction, and low level is cut-off.

[0010] Preferably, the excitation branch includes a battery. 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 switching tube Q15, and the drain electrode of switching tube Q15 is connected to the power supply terminal of the H-bridge. Switching tube Q15 is used to protect the lithium battery and prevent the discharge current from flowing back.

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

[0012] The present invention also adopts the following technical solutions: A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter, adopting the above-mentioned low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter. It is characterized in that the electromagnetic element is excited through a combination of narrow pulses and wide pulses, and the voltage response during the wide pulse excitation and the subsequent discharge period is collected to obtain a flow signal. The amplitude of the flow signal is proportional to the fluid flow rate.

[0013] Different from the prior art method of waiting for the current in the excitation coil and magnetic core to reach a constant value and ensuring the stability of the magnetic field before sampling the induced electromotive force generated thereby, in this technical solution, the flow signals generated during the charging and discharging processes of the collection coil and magnetic core under wide-pulse excitation are collected, which can not only cancel the influence of differential interference, but also further reduce 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. The pre-excitation utilizes the residual magnetism of the electromagnetic element to reduce the differential interference during the secondary excitation.

[0015] Preferably, it includes the following steps: S1, applying a narrow pulse with a time width of Ts to the electromagnetic element for pre-excitation, and providing a discharge circuit with a time width of Ts for energy recovery; S2, under the magnetic field condition after pre-excitation, applying a wide pulse with the same direction and a time width of Td to the electromagnetic element for secondary excitation, providing a discharge circuit with a time width of Td for secondary energy recovery, where Td≥Ts; S3, collecting the flow voltage signals during the secondary excitation and secondary energy recovery time.

[0016] Preferably, step S3 includes: S31, collecting the flow signals during the secondary excitation and secondary energy recovery time for arithmetic averaging to obtain the flow voltage signal, and the flow voltage signal is proportional to the liquid flow velocity in the catheter; S32, collecting the actual voltage of the lithium battery under secondary excitation, calculating the voltage compensation coefficient to compensate the flow voltage signal; S33, collecting the excitation current flowing through the electromagnetic element, calculating the current compensation coefficient to compensate the flow voltage signal.

[0017] Preferably, step S32 includes: S321, collecting the voltage of the lithium battery during the secondary excitation time, dividing the preset standard voltage value by the real-time collected value to obtain the voltage compensation coefficient; S322, multiplying the voltage compensation coefficient by the flow voltage signal to dynamically adjust and compensate for the flow measurement error caused by the voltage drop of the lithium battery.

[0018] Preferably, step S33 includes: S331, collecting the excitation current flowing through the electromagnetic element during the secondary excitation and secondary energy recovery time, dividing it by the excitation current at the time of factory to obtain the current compensation coefficient; S332, multiplying the current compensation coefficient by the flow voltage signal to compensate for the measurement error caused by the external magnetic field.

[0019] The beneficial effects of the present invention are: 1) Use narrow pulses for pre-excitation, and then use wider pulses for excitation to reduce the rate of magnetic field change, minimize the impact of differential interference, and reduce excitation loss; 2) Collect the flow signals generated during the charging and discharging processes of the acquisition coil and magnetic core under wide-pulse excitation, which can not only cancel out the influence of differential interference, but also further reduce the excitation time of the wide pulse, thereby reducing energy consumption; 3) Use a lithium battery for direct power supply, and use an H-bridge to excite the coil and magnetic core. Combined with the excitation voltage sampling compensation technology, it simplifies the circuit, reduces losses, and improves the measurement accuracy at the same time; 4) Through the automatic enhancement mechanism of the excitation current, the magnetic field strength generated by the internal magnetic coil and magnetic core is increased, effectively compensating for the potential interference of the external static magnetic field on the measurement accuracy of the flowmeter, and achieving dynamic balance and precise correction of the influence of the static magnetic field. Description of the Drawings

[0020] Figure 1 is the functional block diagram of a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0021] Figure 2 is the schematic diagram of the excitation drive circuit in a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0022] Figure 3 is the schematic diagram of the excitation circuit of the forward excitation drive in a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0023] Figure 4 is the schematic diagram of the discharge circuit of the forward excitation drive in a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0024] Figure 5 is the schematic diagram of the excitation branch of the reverse excitation drive in a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0025] Figure 6 is the schematic diagram of the discharge circuit of the reverse excitation drive in a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention.

[0026] Figure 7 is the timing diagram of the forward excitation control of the wide and narrow pulses according to the present invention.

[0027] Figure 8 is the timing diagram of the reverse excitation control of the wide and narrow pulses according to the present invention.

[0028] Figure 9 is the flow acquisition timing of the forward excitation of the wide and narrow pulses according to the present invention.

[0029] Figure 10It is the timing sequence of wide and narrow pulse reverse excitation flow acquisition of the present invention.

[0030] Figure 11 It is the schematic diagram of forward excitation differential interference of the present invention.

[0031] Figure 12 It is the schematic diagram of reverse excitation differential interference of the present invention.

[0032] Figure 13 It is the schematic diagram of the magnetic field change rate of the present invention.

[0033] Figure 14 It is the timing schematic diagram of Embodiment 5 of the present invention.

[0034] Figure 15 It is the timing schematic diagram of Embodiment 6 of the present invention.

[0035] Figure 16 It is the timing schematic diagram of Embodiment 7 of the present invention.

[0036] Figure 17 It is the timing schematic diagram of Embodiment 8 of the present invention.

[0037] Figure 18 It is the timing schematic diagram of Embodiment 9 of the present invention.

[0038] Figure 19 It is the timing schematic diagram of Embodiment 10 of the present invention.

[0039] Reference numerals: excitation drive circuit 10; electromagnetic element L11; excitation current I L ; internal diode D16 of switching transistor Q16; conduit 20; positive electrode 21a of electrode; negative electrode 21b of electrode; instrumentation 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 implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific implementation manners described herein are only the best embodiments of the present invention, which are only used to explain the present invention and do not limit the protection scope of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0041] Embodiment 1 This embodiment provides a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter, referring to Figure 1 , including an excitation drive circuit 10, an electromagnetic element L11, a conduit 20, electrodes 21, an instrumentation amplifier 30, an analog-to-digital conversion module 40, and a control module 50.

[0042] The output port of the excitation drive circuit is connected to the electromagnetic element, and the electromagnetic element is arranged near the conduit.

[0043] In this embodiment, the electromagnetic element is composed of a coil and a magnetic core. The excitation drive circuit applies the lithium battery voltage across the two ends of the coil. After a current passes through the coil, a magnetic field will be generated inside the conduit.

[0044] Electrodes are respectively installed on the front and back sides of the conduit. The electrodes pick up the voltage signal generated by the conductive liquid flowing in the pipeline when cutting the magnetic force line, and this voltage signal is proportional to the flow rate.

[0045] The electrodes are connected to the instrumentation amplifier. The instrumentation amplifier differentially amplifies the voltages on the two electrodes, overcomes the common-mode interference, and realizes impedance transformation.

[0046] The instrumentation amplifier is connected to the control module through the analog-to-digital conversion module. The analog-to-digital conversion module performs analog-to-digital conversion on the signal after the instrumentation amplifier, converts the voltage signal into a digital signal, and the control module can excite the electromagnetic element through a combination of narrow pulses and wide pulses.

[0047] In this embodiment, the control module includes a single-chip microcomputer and a timer. On the one hand, the timer generates narrow and wide pulses to drive the excitation drive circuit; on the other hand, it controls the analog-to-digital conversion module to perform specific algebraic operations on the obtained digital signal to obtain the final flow value.

[0048] The excitation circuit is composed of a lithium battery, switching tubes Q11, Q12, Q13, Q14, Q15, Q16, and a capacitor C11. The switching tubes are switching semiconductor devices. In this embodiment, the switching tubes Q11, Q12, Q13, Q14, Q15, Q16 are all N-channel MOS tubes.

[0049] As Figure 2 shown, MOS tubes Q11, MOS tube Q12, MOS tube Q13, and MOS tube Q14 form an H-bridge, and the electromagnetic element is connected between the two output ports of the H-bridge.

[0050] There are two branches connected between the power supply terminal and the ground terminal of the H-bridge, namely the excitation branch and the freewheeling branch, and switching tubes are provided in both the excitation branch and the freewheeling branch.

[0051] Specifically, the excitation branch includes a battery and an MOS transistor 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 transistor Q15, and the drain electrode of the MOS transistor Q15 is connected to the power supply terminal of the H-bridge.

[0052] Among them, the MOS transistor Q15 is used to protect the lithium battery and prevent the discharge current from flowing back.

[0053] The freewheeling branch includes a capacitor C11 and an MOS transistor Q16. The first terminal of the capacitor C11 is connected to the ground terminal of the H-bridge, the second terminal of the capacitor C11 is connected to the drain electrode of the switching transistor Q16, and the source electrode of the switching transistor Q16 is connected to the power supply terminal of the H-bridge.

[0054] Among them, the MOS transistor Q16 and C11 form an energy recovery circuit for collecting the current when the coil discharges.

[0055] The gates of all the switching transistors of the excitation drive circuit are connected to the control module to receive control signals from the control module.

[0056] The control signals S11, S12, S13, S14, S15, and S16 respectively control the switching states of Q11, Q12, Q13, Q14, Q15, and Q16. The high level is for conduction and the low level is for cut-off. The control signals generated by the control module provide an excitation loop without conversion loss and a freewheeling loop with low impedance for the electromagnetic element.

[0057] When current flows through the electromagnetic element L11, a magnetic field environment will be induced in its internal conduit area. At this time, if there is a conductive liquid flowing in the conduit, the liquid will cut this magnetic field, and then induce a voltage signal across the preset electrodes.

[0058] It should be noted that the intensity of this voltage signal is directly proportional to the flow rate of the conductive liquid, and this characteristic provides the basis for flow measurement.

[0059] In addition, due to the inherent properties of the magnetic core material, when the excitation current returns to zero, a certain amount of residual magnetism will remain in the magnetic core for a short time. This residual magnetism phenomenon is cleverly utilized in the present invention to optimize the subsequent measurement process.

[0060] Specifically, the present invention first uses a narrow pulse for pre-excitation, and uses the residual magnetism remaining in the magnetic core after this process as the starting magnetic field condition for the secondary wide pulse excitation.

[0061] Compared with the wide pulse excitation starting from zero magnetic field, this starting condition based on residual magnetism significantly reduces the differential interference generated by L11 during the secondary excitation process.

[0062] The magnitude of differential interference is usually closely related to the rate of change of the magnetic field, and the existence of residual magnetism effectively reduces the intensity of the magnetic field when it changes from zero, thereby reducing the differential interference.

[0063] In summary, by introducing narrow pulse pre-excitation and utilizing the residual magnetism generated thereby, the present invention successfully reduces the differential interference during secondary wide pulse excitation, thereby improving the accuracy of flow measurement.

[0064] The low power consumption excitation system of an electromagnetic water meter and an electromagnetic flowmeter in this embodiment adopts an excitation method combining narrow pulses and wide pulses. It is now defined that the current flows from the left side of the electromagnetic element L11 to its right side as positive, and from the right side of L11 to its left side as reverse.

[0065] The present invention first excites the electromagnetic element L11 with a narrow pulse of time width Ts, and then provides a low-impedance discharge circuit for the electromagnetic element L11. Then, a wide pulse of time width Td is used to excite the electromagnetic element L11 in the same direction for a second time, and then a low-impedance discharge circuit is provided for it.

[0066] For forward excitation drive, it is achieved by turning on Q11, Q14, Q15 and turning off Q12, Q13, Q16. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then flows back to the ground.

[0067] For the discharge circuit after forward excitation, it is achieved by closing Q11, Q14, Q15 and opening Q12, Q13, Q16. At this time, the current is pulled out from the ground terminal and passes through Q12, Q13, Q16 in sequence to charge the C11 capacitor. This process can be understood as energy recovery.

[0068] The current conventional control is to turn off Q11, Q12, Q13, Q14, Q15, and Q16. At this time, the current is pulled out from the ground terminal and passes through the diodes inside Q12, Q13, and Q16 in turn. Compared with the control method of the present invention, this method significantly increases the loss of the diode inside the switch tube and increases the burden on the low-power system.

[0069] For reverse excitation drive, it is achieved by opening Q12, Q13, Q15, Q16 and closing Q11 and Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then flows back to the ground.

[0070] For the discharge circuit after reverse excitation, it is achieved by closing Q12, Q13, Q15 and opening Q11, Q14, Q16. At this time, the current is pulled out from the ground terminal and passes through Q11, Q14, Q16 in sequence to charge the C11 capacitor. This process can be understood as energy recovery.

[0071] Similar to the discharge control method after positive excitation, this method can effectively reduce the loss of the internal diode of the switching tube and relieve the burden on the low-power system.

[0072] It should be noted that the main difference between the wide pulse and the narrow pulse mentioned in the present invention is reflected in the pulse width, and the width Ts of the narrow pulse ≤ the width Td of the wide pulse.

[0073] The wide pulse and the narrow pulse generated by the present invention are applied across the coil, and by controlling the switching tube, the excitation of the forward wide pulse or narrow pulse and the reverse wide pulse or narrow pulse is realized.

[0074] Embodiment 2 This embodiment provides a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter. By combining the wide pulse and the narrow pulse generated above, an innovative coil driving method of pre-excitation is proposed, which specifically includes the following steps: first apply a narrow pulse Ts to the coil, then provide a discharge circuit with a time width of Ts to provide a freewheeling circuit for the current on the coil after narrow pulse excitation; immediately apply a wide pulse Td in the same direction to the coil again, and then provide a discharge circuit with a time width of Td to provide a freewheeling circuit for the current on the coil after wide pulse excitation.

[0075] This excitation method can effectively reduce the coercive force of the coil. According to the low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter of this embodiment, energy recovery immediately enters the discharge circuit after narrow pulse excitation. However, due to the effect of the magnetic hysteresis regression curve of the electromagnetic element L11, there is still a magnetic field intensity of Br in the electromagnetic element L11 after the discharge ends. When applying a wide pulse in the same direction for excitation, the electromagnetic element L11 can reach the magnetic field intensity of Bs faster.

[0076] In this way, on the one hand, the peak value of the differential interference coupled to the signal terminal due to magnetic field changes can be effectively reduced. On the other hand, due to the existence of discharge circuits with widths of Ts and Td, flow signals will also be generated in these circuits. By picking up this part of the flow signals, not only can the differential interference be offset, but also the acquisition period of the flow signal can be extended, and the acquisition stability of the flow signal can be improved.

[0077] In addition, the combination of wide and narrow pulses can reduce differential interference. As Figure 13 shown, when the narrow pulse initially excites the electromagnetic element L11, the initial value of the magnetic field on the electromagnetic element L11 at this time is 0, and the rising slope during excitation is the highest, K1 > K2.

[0078] The peak value of the differential interference coupled to the signal is very high. If this peak voltage is collected for flow calculation, it will have a greater impact on the accuracy. Although it is disclosed in the patent that the differential interference corresponding to the discharge circuit can be collected for compensation, this method cannot completely overcome it.

[0079] However, by adopting the method of the present invention, a wide pulse in the same direction follows immediately after the narrow pulse excitation, which can reduce the slope of the magnetic field change and decrease the peak value of the differential interference, as Figure 12 shown. In addition, by collecting the differential interference signal generated by the discharge circuit after the wide pulse excitation, the differential interference generated during the wide pulse excitation can be effectively cancelled out.

[0080] The present invention collects the flow signal corresponding to the time within the wide pulse excitation and the subsequent discharge circuit, accumulates all the collected voltage values, and the obtained voltage value is proportional to the flow velocity flowing through the pipeline.

[0081] As Figure 12 shown in the flow collection area, the voltage value collected by the present invention is significantly different from that of the prior art.

[0082] First, since narrow pulse excitation is followed by wide pulse excitation, the differential interference generated during the wide pulse excitation is smaller.

[0083] Second, the collection period is 2 times of the Td time. 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 subsequent discharge circuit can cancel each other out.

[0084] Third, the time of 2*Td is generally controlled between 10 ms and 40 ms. The wide pulse is set because it is necessary to leave enough time for analog-to-digital conversion. Since the length of the collection time affects the stability of the digital signal, a longer collection time can, on the one hand, overcome the influence of the thermal noise generated by the amplifier circuit, and on the other hand, can also overcome the influence of the power frequency. If the collection frequency of 10 Khz is matched, then there are 100 - 400 AD values within the corresponding time.

[0085] After the narrow and wide pulse excitations, the present invention provides a specific discharge circuit, which is used for energy recovery on the one hand and also for picking up this part of the differential interference and flow signal on the other hand. The energy recovery is realized through the capacitor C11, and this part of the differential interference is used to compensate the differential interference generated during the wide pulse excitation. During the discharge time of the electromagnetic element L11, the direction of the current on the coil does not change, only the current value gradually becomes smaller. The present invention also particularly focuses on the induced electromotive force generated at both ends of the electrode during this period. By picking up this part of the electromotive force, while increasing the number of samples, the time excited by the wide pulse can be shortened.

[0086] Embodiment 3 Taking the forward excitation as an example, this embodiment further elaborates a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter of the present invention.

[0087] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Ts.

[0088] Turn off Q11, Q14, Q15, and turn on Q12, Q13, Q16. At this time, the current is pulled out from the ground terminal and passes through Q12, Q13, Q16 in sequence to charge the C11 capacitor. This duration is Ts.

[0089] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Td.

[0090] Turn off Q11, Q14, Q15, and turn on Q12, Q13, Q16. At this time, the current is pulled out from the ground terminal and passes through Q12, Q13, Q16 in sequence to charge the C11 capacitor. This duration is Td.

[0091] The flow signal acquisition time is shown in Figure 9 , and by performing arithmetic averaging on the acquired signal, the obtained voltage value is proportional to the flow velocity in the pipeline.

[0092] Embodiment 4 In this embodiment, taking reverse excitation as an example, a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention is further described.

[0093] The most significant difference between this embodiment and Embodiment 3 is the adoption of the reverse excitation method.

[0094] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Ts.

[0095] Turn off Q12, Q13, Q15, and turn on Q11, Q14, Q16. At this time, the current is pulled out from the ground terminal and passes through Q11, Q14, Q16 in sequence to charge the C11 capacitor. The duration is Ts.

[0096] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Td.

[0097] Turn off Q12, Q13, and Q15; turn on Q11, Q14, and Q16. At this time, the current is pulled out from the ground terminal and passes through Q11, Q14, and Q16 in sequence to charge the C11 capacitor for a duration of Td.

[0098] Flow signal acquisition time see Figure 10 , by taking the arithmetic average of the collected signals, the voltage value obtained is proportional to the flow velocity flowing through the pipeline.

[0099] Example 5 This embodiment takes forward excitation + reverse excitation as an example to further illustrate a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter of the present invention. The combination of forward pulse and reverse pulse can prevent the polarization of the electrodes of the electromagnetic water meter or electromagnetic flowmeter under the same-direction pulse excitation, and can overcome the influence of the power frequency according to the same-phase sampling technology.

[0100] Turn on Q11, Q14, Q15, Q16, and turn off Q12 and Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal. The duration width is Ts; turn off Q11, Q14, Q15, and turn on Q12, Q13, Q16. At this time, the current is pulled out from the ground terminal, passes through Q12, Q13, Q16 in turn, and charges the C11 capacitor. The duration is Ts.

[0101] Turn on Q11, Q14, Q15, Q16, and turn off Q12 and Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then flows back to the ground terminal. The duration width is Td; turn off Q11, Q14, Q15, and turn on Q12, Q13, Q16. At this time, the current is pulled out from the ground terminal, passes through Q12, Q13, Q16 in turn, and charges the C11 capacitor. The duration is Td.

[0102] Turn on Q12, Q13, Q15, Q16, and turn off Q11 and Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then flows back to the ground terminal. The duration width is Ts; turn off Q12, Q13, Q15, and turn on Q11, Q14, Q16. At this time, the current is pulled out from the ground terminal, passes through Q11, Q14, Q16 in turn, and charges the C11 capacitor. The duration is Ts.

[0103] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal, with a duration width of Td; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor, with a duration of Td.

[0104] The flow signal acquisition time is shown in Figure 14 , by taking the difference between the voltage value obtained by arithmetic averaging the signal corresponding to the forward excitation signal and the voltage value obtained by arithmetic averaging the signal corresponding to the reverse excitation signal, a voltage signal proportional to the flow rate can also be obtained.

[0105] Embodiment 6 In this embodiment, taking reverse excitation + forward excitation as an example, a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention is further elaborated. The main difference between this embodiment and Embodiment 5 is that the coil is first excited by a reverse wide and narrow pulse, and then immediately excited by a forward wide and narrow pulse.

[0106] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal, with a duration width of Ts; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor, with a duration of Ts.

[0107] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal, with a duration width of Td; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor, with a duration of Td.

[0108] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal, with a duration width of Ts; turn off Q11, Q14, Q15, turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q12, Q13, Q16 to charge the C11 capacitor, with this duration of Ts.

[0109] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Td. Turn off Q11, Q14, Q15, and turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal and passes through Q12, Q13, Q16 in sequence to charge the C11 capacitor. This duration is Td.

[0110] The flow signal acquisition time is shown in Figure 15 , by subtracting the voltage value obtained by arithmetic averaging the signal corresponding to the reverse excitation signal from the voltage value obtained by arithmetic averaging the signal corresponding to the forward excitation signal, a voltage signal proportional to the flow rate can also be obtained.

[0111] Embodiment 7 In this embodiment, taking forward excitation + reverse excitation + reverse excitation + forward excitation as an example, a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to the present invention will be further described. This embodiment combines Embodiment 5 and Embodiment 6, and this combined method is particularly suitable for scenarios where the influence of the DC drift amount needs to be overcome under low power consumption.

[0112] The control feature of this method is to first perform forward narrow-width pulse excitation and reverse narrow-width pulse excitation on the coil, and after a certain time interval, perform reverse narrow-width pulse excitation and forward narrow-width pulse excitation on the coil, and collect the voltage values under wide pulse excitation for arithmetic averaging and linear operation to obtain a flow value that can overcome the DC drift amount. The specific operation steps are as follows.

[0113] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Ts. Turn off Q12, Q13, Q15, and turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal and passes through Q11, Q14, Q16 in sequence to charge the C11 capacitor. The duration is Ts.

[0114] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Td. Turn off Q12, Q13, Q15, and turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal and passes through Q11, Q14, Q16 in sequence to charge the C11 capacitor. The duration is Td. Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Ts; turn off Q11, Q14, Q15, turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal, passes through Q12, Q13, Q16 in sequence, and charges the C11 capacitor. This duration is Ts.

[0115] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Td; turn off Q11, Q14, Q15, turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal, passes through Q12, Q13, Q16 in sequence, and charges the C11 capacitor. This duration is Td.

[0116] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Ts; turn off Q11, Q14, Q15, turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal, passes through Q12, Q13, Q16 in sequence, and charges the C11 capacitor. This duration is Ts.

[0117] Turn on Q11, Q14, Q15, Q16, and turn off Q12, Q13. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q11, coil L11, Q14, and then returns to the ground terminal. The duration width is Td; turn off Q11, Q14, Q15, turn on Q12, Q13, Q16. At this time, the current is pulled from the ground terminal, passes through Q12, Q13, Q16 in sequence, and charges the C11 capacitor. This duration is Td. Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Ts; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, passes through Q11, Q14, Q16 in sequence, and charges the C11 capacitor. The duration is Ts.

[0118] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Td; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor. The duration is Td.

[0119] The flow signal acquisition time is shown in Figure 16 , perform an addition operation on the signals corresponding to the two positive and reverse excitation signals respectively, and then subtract the arithmetic mean voltage value of the two positive excitations and the two reverse excitations to obtain a voltage signal with the DC drift removed. This voltage signal is proportional to the flow rate.

[0120] Embodiment 8 This embodiment takes multiple narrow pulses + wide pulses as an example to further elaborate on a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter of the present invention. This embodiment adopts a combination of multiple narrow pulses and a single wide pulse. When actually implementing the above solution, due to the large difference in the inductance of the electromagnetic element L11 driven, especially when driving a load with a relatively large inductance, multiple narrow pulse excitations may be required to reduce the influence of differential interference. The specific operation steps are as follows.

[0121] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Ts; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor. The duration is Ts.

[0122] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal. The duration width is Ts; turn off Q12, Q13, Q15, turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal, and successively passes through Q11, Q14, Q16 to charge the C11 capacitor. The duration is Ts.

[0123] Turn on Q12, Q13, Q15, Q16, and turn off Q11, Q14. At this time, the current starts from the positive terminal of the lithium battery, flows through Q15, Q12, coil L11, Q13, and then returns to the ground terminal, with a duration width of Td; turn off Q12, Q13, Q15, and turn on Q11, Q14, Q16. At this time, the current is pulled from the ground terminal and passes through Q11, Q14, Q16 in sequence to charge the C11 capacitor, with a duration of Td.

[0124] The flow signal acquisition time is shown in Figure 17 , and by performing arithmetic averaging on the acquired signal, the obtained voltage value is proportional to the flow velocity in the pipeline.

[0125] It should be noted that regarding the combined excitation of wide pulses and narrow pulses, in actual implementation, we can adopt various methods of combining wide and narrow pulses, including but not limited to: forward narrow pulse + forward narrow pulse discharge + forward wide pulse + forward wide pulse discharge; reverse narrow pulse + reverse narrow pulse discharge + reverse wide pulse + reverse wide pulse discharge; forward narrow pulse + forward narrow pulse discharge + forward wide pulse + forward wide pulse discharge + reverse narrow pulse + reverse narrow pulse discharge + reverse wide pulse + reverse wide pulse discharge; reverse narrow pulse + reverse narrow pulse discharge + reverse wide pulse + reverse wide pulse discharge + forward narrow pulse + forward narrow pulse discharge + forward wide pulse + forward wide pulse discharge.

[0126] Although the above embodiments only mention several relatively representative methods, as long as the excitation method is based on wide and narrow pulses, it should fall within the protection scope of this patent. And according to the magnitude of the inductance of the electromagnetic element L11 to be excited, the width Td of the wide pulse can be not less than the width Ts of the narrow pulse, that is, Td ≥ Ts.

[0127] Embodiment 9 This embodiment proposes a voltage compensation method in the low-power excitation method of an electromagnetic water meter and an electromagnetic flowmeter, which can compensate for the measurement error caused by the decrease in the voltage of the lithium battery.

[0128] The present invention adopts a very simple method. Instead of using a constant current source in the circuit, it simply applies the voltage of the lithium battery. This method will have a measurement error caused by the change in the voltage of the lithium battery. Therefore, during the coil excitation period of the present invention, the voltage across the lithium battery is collected for compensation, and the voltage compensation coefficient is obtained by dividing the factory voltage value by the collected voltage value for use in flow calculation. The following elaborates on the specific calculation method.

[0129] When the power supply voltage of the lithium battery is insufficient, the voltage V of the lithium battery can be collected BATT-R , and the acquisition timing is as Figure 18 shown, and the obtained voltage value is compared with the factory lithium battery voltage V BATT-P to obtain the 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 in voltage.

[0130] Example 10 This embodiment provides a current compensation method in a low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter, which is used to compensate for the influence of an external static magnetic field on the electromagnetic water meter or the electromagnetic flowmeter.

[0131] When the external static magnetic field approaches, since the coil driving circuit of the present invention does not sample the constant current mode, when the external magnetic field approaches the electromagnetic water meter or electromagnetic flow meter, under the influence of the external magnetic field, the excitation current will increase and the flow signal will decrease.

[0132] Although the increased excitation current has compensated for part of the influence of the external magnetic field, the present invention also compensates by collecting the current at both ends of the flow coil, and compensates the flow value by the coefficient obtained by dividing the reduced excitation current by the factory excitation current, which can overcome the influence of the external static magnetic field during the use of the electromagnetic water meter or electromagnetic flowmeter. The specific calculation method is described below.

[0133] Collect the excitation current I flowing through the coil R , the acquisition timing is as follows Figure 18 As shown, the collected current value is compared with the factory excitation current I P By comparison, the current compensation coefficient is obtained The measurement error caused by the external magnetic field is compensated by multiplying the collected flow voltage signal with the current compensation coefficient.

[0134] In dealing with the problem of static magnetic field interference, different from the magnetic shielding technology used in the prior art, when encountering a situation where an external static magnetic field is close to an electromagnetic water meter or an electromagnetic flow meter, the excitation drive circuit of the present invention can show unique adaptability.

[0135] Specifically, the approach of the external static magnetic field will cause the internal magnetic field to decay naturally, but this change not only does not cause adverse effects, but triggers the automatic enhancement mechanism of the excitation current. This mechanism cleverly increases the magnetic field strength generated by the internal magnetic coil and core, thereby effectively compensating for the potential interference of the external static magnetic field on the flow meter's measurement accuracy, and achieving dynamic balance and precise correction of the influence of the static magnetic field.

Claims

1. A low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter, characterized in that It includes a catheter and an excitation drive circuit connected with an electromagnetic element. The electromagnetic element generates a magnetic field inside the catheter. Electrodes are respectively installed on the front and back sides of the catheter. The electrodes are connected with an instrumentation amplifier. The instrumentation amplifier is connected with a control module through an analog-to-digital conversion module. The control module excites the electromagnetic element through a combination of narrow pulses and wide pulses.

2. The low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter according to claim 1, characterized in that, The excitation drive circuit includes an H-bridge composed of four switching tubes. An excitation branch and a freewheeling branch are connected between the power supply terminal and the ground terminal of the H-bridge. Switching tubes are provided in the excitation branch and the freewheeling branch. The electromagnetic element is connected between two output ports of the H-bridge. The gates of the switching tubes receive control signals output by the control module.

3. The low-power excitation system of an electromagnetic water meter and an electromagnetic flowmeter according to claim 2, characterized in that, The excitation branch includes a battery. 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 switching tube Q15. The drain electrode of switching tube Q15 is connected to the power supply terminal of the H-bridge.

4. A low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to claim 2 or 3, characterized in that The freewheeling branch includes a capacitor C11. 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 switching tube Q16. The source electrode of switching tube Q16 is connected to the power supply terminal of the H-bridge.

5. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter, which uses a low-power excitation system for an electromagnetic water meter and an electromagnetic flowmeter according to any one of claims 1-4, characterized in that, The electromagnetic element is excited by a combination of narrow pulses and wide pulses. The voltage response during the wide pulse excitation and the subsequent discharge period is collected to obtain a flow signal. The amplitude of the flow signal is proportional to the fluid flow rate.

6. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to claim 5, characterized in that, The combined excitation includes: first applying a narrow pulse for pre-excitation, and then applying a wide pulse for secondary excitation. The pre-excitation utilizes the residual magnetism of the electromagnetic element to reduce the differential interference during the secondary excitation.

7. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to claim 5 or 6, characterized in that It includes the following steps: S1, apply a narrow pulse with a time width of Ts to the electromagnetic element for pre-excitation, and provide a discharge circuit with a time width of Ts for energy recovery; S2, under the magnetic field condition after pre-excitation, apply a wide pulse with the same direction and a time width of Td to the electromagnetic element for secondary excitation, and provide a discharge circuit with a time width of Td for secondary energy recovery, Td≥Ts; S3, collect the flow voltage signal during the secondary excitation and the secondary energy recovery time.

8. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to claim 7, characterized in that, The step S3 includes: S31, collect the flow signals during the secondary excitation and the secondary energy recovery time and perform arithmetic averaging to obtain a flow voltage signal. The flow voltage signal is proportional to the liquid flow velocity in the catheter; S32, collect the actual voltage of the lithium battery under the secondary excitation, calculate the voltage compensation coefficient and perform voltage compensation on the flow voltage signal; S33, collect the excitation current flowing through the electromagnetic element, calculate the current compensation coefficient and perform current compensation on the flow voltage signal.

9. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to claim 8, characterized in that, The step S32 includes: S321, collect the voltage of the lithium battery during the secondary excitation time, divide the preset standard voltage value by the voltage collected in real time to obtain the voltage compensation coefficient; S322, multiply the voltage compensation coefficient by the flow voltage signal to dynamically adjust and compensate for the flow measurement error caused by the voltage drop of the lithium battery.

10. A low-power excitation method for an electromagnetic water meter and an electromagnetic flowmeter according to claim 8, characterized in that, The step S33 includes: S331, collect the excitation current flowing through the electromagnetic element during the secondary excitation and the secondary energy recovery time, divide it by the excitation current at the time of factory to obtain the current compensation coefficient; S332, multiply the current compensation coefficient by the flow voltage signal to compensate for the measurement error caused by the external magnetic field.

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