Ultrahigh-frequency resonance excitation low-power-consumption electromagnetic flowmeter and special chip thereof

Abstract

The utility model relates to an ultrahigh frequency resonance excitation low power consumption electromagnetic flowmeter and a special chip thereof, a sensor core is installed in a sensor core waterproof box, the sensor core waterproof box is installed at the middle position of a sensor core support, and the sensor core waterproof box divides a measuring pipeline in the sensor core support into two parts. Signal processing PCBs are installed on the front face and the back face of the sensor core support respectively, special chips are arranged in the two signal processing PCBs respectively, and the sensor core support is installed in a metal pipeline. According to the utility model, the purpose of reducing power consumption is realized by shortening the excitation time and forming resonance by using inductance and capacitance of the excitation coil; and the excitation coil and the measurement electrode are manufactured by adopting the multi-layer PCB, so that the manufacturing cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of electromagnetic flowmeter, especially relates to a superhigh frequency resonant excitation low -power consumption electromagnetic flowmeter and its special chip. BACKGROUND

[0002] Electromagnetic flowmeter is a kind of high-precision, long-life flowmeter designed using the principle of electromagnetic induction law, and its basic principle is that the flowing conductive liquid cuts the magnetic force line in the direction of movement to generate induced electromotive force at both ends of the liquid.If the magnetic induction intensity is constant B, then according to the electromagnetic induction law, the induced electromotive force U = BLV is generated, B is the magnetic induction intensity, L is the water flow width of effective cutting magnetic force line, V is the water flow velocity, and U is the size of induced electromotive force. Therefore, as long as the constant magnetic induction intensity B is constant, and the pipeline parameter L is fixed, U is proportional to V, U = K * V, and the water flow velocity V can be calculated by measuring the value of U. The water flow velocity multiplied by the cross-sectional area of the pipeline can obtain the volumetric flow rate of the flowmeter: Flux = V * S, S is the effective cross-sectional area of the pipeline.

[0003] The above is the working principle of electromagnetic flowmeter, and the disadvantages of electromagnetic flowmeter can be inferred as follows:

[0004] First, the power consumption is large, and the electromagnetic flowmeter needs a large excitation current when realizing water flow measurement due to the polarization effect of water. There is an uncertain polarization voltage between the two measurement electrodes, and alternating excitation is needed to overcome the polarization voltage, and permanent magnet excitation cannot be used, which leads to the need for a large excitation current of the electromagnetic flowmeter.

[0005] Second, the cost is high, and the electromagnetic flowmeter needs a large excitation coil and an insulating layer inside the pipeline, so the manufacturing cost is high.

[0006] At present, household water meters are developing towards intelligentization, but due to the limitation of cost and technical maturity, the intelligentization of household water meters is generally realized by adding a mechanical-electrical conversion device on the basis of mechanical instruments. The advantages of this intelligent direction are: good technical continuity, retention of the durability of mechanical water meters, etc. But the disadvantages are also very obvious: mechanical to electrical conversion is needed, precision is difficult to improve, base meter life is short, etc.

[0007] Therefore, the industry has long hoped to find a full electronic way of household intelligent water meter, and many companies in the global measurement industry have made continuous efforts for this purpose. At present, the more promising methods include ultrasonic flowmeter and electromagnetic flowmeter. The advantages of ultrasonic flowmeter are high precision and low power consumption, but the disadvantages are also very obvious: the noise resistance of the transducer is poor, and there is a high probability of damage under strong vibration and thermal fatigue. There is no good way to overcome it at present. Electromagnetic flowmeter has the advantages of high precision, long service life and good noise resistance, but its power consumption and cost have become the industry's hard point.

[0008] Therefore, the present application designs a super-high frequency resonance excitation magnetic low-power electromagnetic flowmeter and its special chip, which is aimed at the power consumption and cost disadvantages of electromagnetic flowmeter. A very novel and effective method is used to overcome these two disadvantages of electromagnetic flowmeter, opening up a new way for the full electronic of water meter. SUMMARY

[0009] The utility model discloses in order to make up for the deficiency in the prior art, provide a super-high frequency resonance excitation magnetic low-power electromagnetic flowmeter and its special chip. Its basic design idea is: first, by reducing excitation time and using the inductance and capacitance of excitation coil to form resonance, the purpose of reducing power consumption is realized. Second, a multilayer PCB is used to manufacture the excitation coil and the lead-out of the measuring electrode, thereby greatly reducing the manufacturing cost.

[0010] The utility model discloses a super-high frequency resonance excitation magnetic low-power electromagnetic flowmeter and its special chip, which are realized through the following technical schemes:

[0011] 1, mechanical structure

[0012] The main advantage structure part of the super-high frequency resonance excitation magnetic low-power electromagnetic flowmeter of the utility model is that the excitation winding and the electrode are integrally formed on the PCB. This component, as the most core component of the flow sensor, is named "sensor core" for convenience of description. The "integrally formed excitation winding and electrode", also called sensor core, is manufactured by using a multilayer PCB to manufacture the excitation winding and the lead-out of the measuring electrode. The advantage of manufacturing by using a PCB process is that the process repeatability is high, the manufacturing cost is low, and the structure is compact.

[0013] The preferred manufacturing process is to use a multilayer PCB, in which the excitation winding occupies the inner layer metal, and the measuring electrode occupies the surface metal. The PCB has two surfaces, Top and Bottom. The measuring electrode is manufactured on both the Top and Bottom layers. The two electrode signals are connected in series and then led out. This has the advantage of doubling the measurement signal amplitude.

[0014] The electrode welding pad is welded with a measuring electrode, which is preferably made of stainless steel due to its contact with water, and can also be made of hastelloy or other corrosion-resistant metal or alloy.

[0015] The excitation coil and the measuring electrode lead-out pad are manufactured by using a multi-layer PCB process, which has the advantages of low manufacturing cost and good process repeatability. However, the coil resistance is large due to the small thickness of the PCB copper foil, and the test data of the sample shows that the coil resistance is about 1.5 ohms, which results in a small excitation current of about 2A and a small Q value of 50-100 of the resonant circuit under the condition of direct power supply of a 3.6V battery.

[0016] To solve this problem, the measuring electrode lead-out pad and lead-out circuit can be manufactured by using a PCB, and the excitation coil is wound by using an enameled wire.

[0017] A double-sided PCB with a thickness of 0.6mm is preferably used as an electrode support, and a single-layer enameled wire is pasted on the upper and lower surfaces of the PCB, as shown in the green line part of the schematic diagram. If the enameled wire pasted on the upper and lower surfaces of the PCB has a thickness of 0.5mm, the total thickness is 1.6mm. This is the preferred design, and the effective thickness of the sensor core is as thin as possible, which can provide a large pipe area for the flowmeter and reduce the pressure loss.

[0018] The use of enameled wire winding for excitation winding has the advantages of small coil resistance, which can greatly improve the Q value of the resonant excitation resonant circuit and obtain a large excitation current, improve the measurement signal amplitude, and the inventors used an enameled wire with an outer diameter of 0.5mm to wind 16 turns in a single layer and 32 turns in two layers during trial production. The actual inductance is 22uH, and the winding resistance is only 0.16 ohms. When the excitation frequency is 1Mhz, the inductance impedance ZL = 138.2 ohms, and the resonant circuit Q value can theoretically reach Q = 138.2 / 0.16 = 864. The maximum excitation current can theoretically reach 3.6V / 0.16 ohms = 22.5A. A high Q value means that only a small amount of energy is needed to excite for a long time, which is more conducive to reducing power consumption.

[0019] In order to realize the electrical and water isolation, the "sensor core" made of multi-layer PCB needs to be installed inside a plastic shell. For the convenience of description, it is named as "sensor core box", which is preferably made of water-resistant plastic, such as PPO or PPS, etc. Two electrode lead holes are made on the bottom surface of the sensor core box. In order to achieve better waterproof effect, when the sensor core is installed inside the "sensor core box", epoxy resin potting glue should be filled inside the "sensor core box" at the same time. The method of directly injection molding the sensor core into the plastic can also be used to realize the electrical and water isolation.

[0020] In order to realize the flow measurement, the electromagnetic flowmeter core support, which is also called as "sensor core support", is designed. The sensor core support is made of water-resistant plastic, such as nylon, polyphenylene sulfide (PPO), polysulfone (PPS), etc. The sensor core support is a cylindrical pipeline, the middle of which is a measuring pipeline. A magnetic shielding band winding limiting groove is opened in the middle position of the outer side of the cylindrical pipeline. After the waterproof sensor core and the signal processing PCB and excitation driving PCB are installed in place, the magnetic shielding band can be wound in the "magnetic shielding band winding limiting groove". The magnetic shielding band is made of permalloy strip, with a thickness of about 0.05-0.1 mm. The magnetic shielding band is wound in multiple layers to form external magnetic shielding, with a winding thickness of about 0.5 mm. "Signal processing PCB mounting cavities" are opened on the two sides of the sensor core support. The electromagnetic flowmeter signal processing PCB and excitation signal driving PCB are installed in the two cavities. One of the cavities is used to install the excitation signal driving PCB, and the other cavity is used to install the measuring signal processing PCB. A sensor core waterproof box mounting slot hole with two circular arcs is opened in the middle of the signal processing PCB mounting cavity. The slot hole penetrates through the upper and lower signal processing PCB mounting cavities, and is used to install the waterproof sensor core. From the structure, it can be seen that the waterproof sensor core is installed in the middle of the measuring pipeline. A "waterproof glue potting cavity" is opened around the waterproof sensor core mounting slot hole. When the waterproof sensor core is installed in the waterproof sensor core mounting slot hole, epoxy resin sealing glue needs to be filled in the cavity to realize the water and electricity isolation between the measuring pipeline and the electrical part.

[0021] After the combination of the sensor core support and the waterproof sensor core, it is called as "electromagnetic flowmeter measuring core". After the waterproof sensor core is inserted into the sensor core support, the measuring pipeline is divided into two parts, and the waterproof sensor core is in the middle of the measuring pipeline. The advantages of this are as follows: first, the excitation signal is in the middle of the pipeline, far away from the magnetic field shielding layer metal and the outer pipeline metal of the electromagnetic flowmeter. When high-frequency resonant excitation is realized, the absorption of these metal layers is minimized, and the excitation coil can maintain a very high Q value. Second, the pipeline is divided into two parts, so the measuring signal can be divided into two parts. The two measuring signals can be connected in series to obtain 2 times of the measuring voltage, so the measuring accuracy is higher.

[0022] The electromagnetic flowmeter's measuring core is surrounded by a magnetic shielding strip. The magnetic shielding strip has signal lead-out holes. The magnetic shielding strip provides excellent shielding, preventing changes in the external magnetic circuit from affecting measurement accuracy. This invention preferably uses a 0.1mm thick permalloy strip as the magnetic shielding layer material, wound in 4-5 layers to form a total magnetic shielding layer with a thickness of 0.4-0.5mm. Alternatively, pure iron or silicon steel can be used to manufacture the shielding strip, which would be more cost-effective. The signal lead-out holes on the shielding strip allow the electromagnetic flowmeter to output power and signals to the outside.

[0023] The electromagnetic flowmeter measuring core is the core measuring component of this invention. To prevent short circuits in the electrical signal caused by the metal pipe, the measuring core requires an extension of an "inner liner" at both the upstream and downstream ends. The inner liner is made of a water-resistant plastic material, such as nylon, polyphenylene sulfide (PPO), or polysulfone (PPS). The inner liner is glued into the "inner liner slot" on the electromagnetic flowmeter measuring core. "Sealing ring grooves" are formed on the two top surfaces of the cylindrical portion of the electromagnetic flowmeter measuring core for installing sealing rings. These sealing rings prevent water from bypassing the gap between the metal pipe and the inner liner and entering the electrical signal cavity. One sealing ring is installed at each end of the electromagnetic flowmeter measuring core, ensuring a seal on both sides.

[0024] The electromagnetic flowmeter's measuring core, which includes an inner liner, needs to be encased in a metal pipe. This metal pipe consists of an upstream pipe and a downstream pipe, which are secured together with screws. The upstream pipe has signal lead-out holes and an electrical housing mounting base. The waterproof sensor core is vertically installed in the pipe, dividing it in two. The plane of the waterproof sensor core is perpendicular to the plane of the electrical housing mounting base, meaning that vertically, the waterproof sensor core splits the water flow into left and right streams. This installation orientation reduces the deposition of impurities in the water flow onto the electrode surface of the waterproof sensor core, improving its anti-fouling ability and extending the flowmeter's lifespan.

[0025] A sealing ring installed on the top surface of the cylindrical part of the electromagnetic flowmeter's measuring core, located between the upstream and downstream metal pipes and the inner liner, ensures a seal between the pipes and the measuring core. This prevents water from entering the electrical processing chamber of the electromagnetic flowmeter through the gap between the metal pipes and the inner liner. To further enhance the sealing effect, sealant can also be applied between the metal pipes and the inner liner.

[0026] 2. Circuit Design

[0027] The ultra-high frequency resonant excitation of this invention is the key to achieving low power consumption, so a separate chapter is dedicated to describing the circuit design of this invention.

[0028] The utility model relates to a kind of low-power electromagnetic flowmeter of superhigh frequency resonance excitation, to obtain good power consumption characteristics and signal measurement characteristics, the precise drive of excitation circuit, high gain amplification of signal, high-speed data acquisition, temperature compensation and other signal processing need to be realized, therefore need to design two special chips, one of which is used to realize excitation and synchronous signal output, another chip is used to realize the processing of measurement signal, finally obtain flow signal.

[0029] (1) superhigh frequency resonance excitation

[0030] The consumption of excitation is the biggest factor leading to the excessively high power consumption of electromagnetic flowmeter, so how to reduce excitation consumption and successfully complete flow measurement is the key to realize low-power electromagnetic flowmeter.

[0031] The utility model realizes two key innovative designs of superhigh frequency resonance excitation: first, excitation coil is installed in the middle of pipeline, away from metal components, so that high-frequency electromagnetic field can not be absorbed by metal, excitation coil maintains high Q value, and measurement of electromagnetic flowmeter is realized by using resonant current repeated oscillation; second, efficient excitation and high-Q low-loss drive circuit are needed.

[0032] As shown in Figure 12 L1 is excitation winding, the inventor tries to prepare a kind of excitation winding inductance about 22uH, which is used as an example as the calculation basis for supporting the utility model; C1 is resonance capacitor, N1 and N2 are two N-channel MOS tubes, which are connected in reverse series to form a bidirectional analog switch structure. When DRV1=high, DRV2=low, and the pressure difference is enough to drive MOS tube to turn on, excitation coil L1 charges energy storage through VCC, and the final energy storage current of L1 can be controlled by driving time. Assuming that the maximum energy storage current is 2A, the current stops driving DRV1 and DRV2 after reaching, and the bidirectional analog switch composed of N1N2 is turned off. At this time, L1 and C1 form a free LC resonance, and the resonance frequency is about: F=1 / (2*PI*SQRT(LC)=1.0231Mhz. Assuming that the winding direct-current resistance is about 1.5 ohms, the Q value of LC loop is about: Q=ZL / R=92.3. The Q value shows that the energy loss of LC loop oscillation in one cycle is very small, about only 1 / 100, so only a very short excitation pulse is needed to obtain a long measurement opportunity. This is an important innovation point of the utility model, and a long measurement time can be obtained by using high-Q oscillation of LC loop after short-time high-current excitation.

[0033] According to the 3.6V power supply calculation, L*di / dt = 3.6V, the inductance value 22uH and the final excitation current 2A can be calculated, and the excitation driving time dt = 12.22uS, according to the calculation of 1 second measurement, the average power consumption of excitation is:

[0034] I = 0.5 * 2A * 12.22uS / 1S = 12.22uA.

[0035] And the Q value of LC circuit can provide at least 100 cycles of measurement, according to the measurement time of 100 cycles, the time left for measurement is 97.8uS, in this time, the excitation magnetic field is provided by LC resonant circuit, and the power supply current is not consumed any more, which is the fundamental reason for the super low power consumption characteristics of the utility model.

[0036] In order to realize the excitation drive of the excitation coil and the LC resonance maintenance of high Q value after the excitation drive is over, N1N2 is reversely connected in series to form a bidirectional analog switch, which can block both forward signal and reverse signal when the analog switch is off, the excitation inductance L1 and the resonant capacitor C1 form an LC free resonant circuit, if L1 is made of PCB coil, the Q value can reach more than 90, if it is made of enameled wire, the Q value can reach more than 800.

[0037] N1N2 should be high-voltage MOS tube, according to the resonant initial current 2A, the resonant frequency is calculated as 1.0231MHZ, the resonant impedance is 141 ohm, the resonant voltage is as high as 282Vac, and the peak voltage is as high as 397V, therefore N1N2 should be high-voltage MOS tube, preferably SiC MOS tube, the advantages of SiC MOS tube are: the output capacitance Coss of the device is small, the DS leakage current is small, the driving efficiency is high, and the Q value of LC circuit is high. Of course, GaN MOS or Si MOS can also be used, the disadvantage is that the DS leakage current is large, the Q value of LC circuit is low, and it is the secondary option of the utility model.

[0038] In order to further improve the Q value, higher resonant frequency can be selected, for example, the resonant frequency is increased to 2Mhz, the excitation winding made of PCB can also reach Q = 282 / 1.5 = 188, and the excitation winding made of enameled wire Q = 282 / 0.16 = 1762.5, under such high Q value, more excitation cycle measurement time can be obtained, and the measurement accuracy can be effectively improved, and the average excitation current is only 12-15uA, which is the most innovative design of the utility model.

[0039] However, the resonant frequency is doubled, the voltage of the analog switch is also doubled, and the resonant voltage is as high as 562Vac, and the peak voltage is as high as 795V, so the analog switch preferably uses SiC MOS with good voltage withstand characteristics.

[0040] (2) Separation of excitation signal driving and measurement signal

[0041] The utility model discloses from structure to separate excitation driving signal and measurement signal, wherein excitation signal occupies one side of sensor core and leads out, and measurement signal occupies another lead-out end, and excitation driving PCB and measurement signal processing PCB are separated from each other on the circuit, and excitation resonance large current forms a loop, so that the interference of excitation current to measurement signal can be greatly reduced.

[0042] In order to limit the large current of excitation resonance loop on the excitation driving board, the utility model discloses Figure 13 excitation driving circuit, C2C3 is power filter capacitor, L1C1 and Cx constitute a resonance loop, Cx is the distributed capacitance of analog switch, due to the existence of Cx, a part of the resonance current will flow through the power supply, but due to the small Cx, for example, using SiC MOS, Cx can be reduced to 100P below, according to 100P, the resonance voltage is calculated as 280Vac, the power filter capacitor is calculated as 4.8uF, and the residual voltage of Cx in series with the power supply is 5.8mV, so it can be ignored. In this way, the excitation resonance current can be limited in the L1C1CX loop, and will not form interference to other circuits through the power supply. In order to further reduce the coupling of excitation resonance current to other circuits through the power supply, the power filter capacitor can be increased, for example, to 10uF or even larger. If increased to 10uF, the resonance current converted to the residual voltage of the power supply can be lower than 2.8mV.

[0043] (3) Measurement signal processing circuit

[0044] The disadvantage of electromagnetic flowmeter is that the measurement signal amplitude is very small, so a high-gain amplifier is needed to amplify the measurement signal, and the high-gain amplifier is easily disturbed or self-excited, which finally leads to measurement failure. The measurement signal estimation method of the ultra-high frequency resonant excitation low-power electromagnetic flowmeter disclosed in the utility model is as follows:

[0045] The actual manufacturing area of the excitation PCB coil is 2.75cm 2 The number of turns is 32, and the inductance is 21.6uH. When the excitation current is 2A, the calculation of the surface magnetic induction intensity B of the coil is as follows: L * di / dt = N * dΦ / dt, and further derivation is as follows: L * di = N * dΦ

[0046] Substitute L and di and the value of N, then the dΦ = 21.6uH * 2A / 32 = 1.35uWb can be calculated

[0047] Then according to B*S =dΦ, and substitute the coil effective area 2.75cm 2 B = 1.35uWb / 2.75cm 2 = 4.9mT.

[0048] Then according to the law of electromagnetic induction U = BLV, L is the distance of the measuring electrode = 15mm, V is the flow rate, according to the lowest 8mm / S, substitute the above formula, U = 4.9mT * 15mm * 8mm / S = 588nV is calculated, and the utility model adopts the double-sided measuring electrode series connection mode, and the measurement voltage can be doubled, so the minimum output voltage = 1.176uV.

[0049] According to the measurement range ratio 400, the maximum signal output voltage = 1.176uV * 400 = 470.4uV.

[0050] If the maximum signal is amplified to 3V, the required amplification factor Av = 3000mV / 0.47mV = 6383 times.

[0051] Therefore, the amplifier should have an amplification factor of 5000-10000 times. This is a serious challenge, and the most serious problem is: the amplifier self-excitation.

[0052] In order to solve the self-excitation problem that may be formed by the high-gain amplification circuit, the utility model adopts "high-frequency passband amplification" and "low-pass amplification", two-stage series connection type amplification circuit, and the two passband is pulled apart by a large distance, eliminating the coupling of the front and rear amplification, avoiding self-excitation:

[0053] First, under the high-frequency resonant excitation magnetic adjustment component, the measuring electrode outputs the same AC signal as the excitation current waveform, assuming that the resonant frequency is about 1Mhz, then the electrode output signal is also 1Mhz AC, therefore the front stage of the amplifier circuit can be designed as: 0.5-1.5Mhz bandwidth passband AC amplifier, the amplification factor is controlled in 100-250 times, this times of amplifier is relatively easy to realize, and will not appear self-excitation, and has high anti-interference ability.

[0054] Secondly, the synchronous rectification realizes AC-DC conversion. It has been described above that the original signal outputted by the measuring electrode of the electromagnetic flowmeter is a high-frequency AC signal. Assuming that the excitation resonance frequency is about 1Mhz, the original signal is also a 1Mhz signal. However, such a high-frequency AC signal is not conducive to direct ADC sampling of the single-chip microcomputer. The best solution is to convert the AC signal into DC. The most commonly used circuit for AC-DC conversion is diode rectification. However, it is well known that the diode does not have ideal rectification characteristics. The turn-on voltage of the diode will cause the rectification to be nonlinear. Especially when the signal amplitude is small, the rectification nonlinearity of the diode will cause a serious deviation.

[0055] To solve this problem, the utility model adopts "synchronous rectification", and the synchronous source is the resonance voltage signal of the excitation resonance loop. According to the electromagnetic induction law U = BLV, it can be determined that the induced electromotive force U is synchronous with the magnetic induction intensity B. According to the Biot-Savart law (or Ampere's law), B is synchronous with the current. Therefore, it can be concluded that the output signal of the electromagnetic flowmeter is synchronous with the excitation resonance loop. Therefore, it is necessary to shape the excitation resonance signal to obtain a square wave signal of a logic level, which is the signal detection (rectification) "synchronous signal". This synchronous signal generation circuit needs to be designed inside the "excitation drive" special chip.

[0056] The signal preamplifier adopts an AC passband amplifier. The amplification factor is preferably 100-250 times. According to the calculation of 200 times, after the original signal is amplified, the output voltage is about 235uV-94mV, and it is an AC signal with a frequency of about 1Mhz. Then it enters the synchronous rectification circuit. The synchronous rectification is designed in a full-wave rectification mode. The rectification switch uses a MOS tube. The gate of the MOS tube is driven by a synchronous signal. See Figure 14 :

[0057] N1N2N3N4 are four N channel MOS transistors, which constitute a bridge type synchronous rectification circuit, the front stage alternating current amplifier adopts differential output, and becomes a pure alternating current signal after being isolated from direct current components by C1C2. N3N2 is driven by DRV1 and DRV2 forward rectifiers, and has the same phase as the synchronous signal, when the synchronous signal is high, N3N2 is turned on, and the bridge circuit is output through N3N2. N1N4 is driven by NOT1 and NOT2 reverse rectifiers, and has opposite phase with the synchronous signal, when the synchronous signal is low, N1N4 is turned on, and the bridge circuit is output through N1N4. C3C4R1 constitutes a π type filter circuit, and filters out the pulsating component in the rectified signal, and the detection output becomes a direct current pulse. Finally, the detection signal is converted from a high frequency alternating current of about 1Mhz to a direct current pulse, the direct current pulse width is calculated according to 100uS, the frequency is about 10Khz, after detection, the signal frequency has been greatly shifted, from the original 1Mhz to 10Khz, so the output of the rear stage amplifier will not be coupled to the front stage amplifier, and thus the self-excitation of the high gain amplifier can be effectively avoided, and the rear stage amplifier adopts a low pass amplifier with a turning frequency of about 50Khz

[0058] The passband of the front stage amplifier completely avoids the low passband of the rear stage, so the rear stage amplifier will not produce self-excitation coupling to the front stage. The amplification multiple of the rear stage low pass amplifier can be set to: 50 - 100 times. The total amplification multiple: 5000 - 25000 times, and the multiple is adjustable, so that it can meet the use of electromagnetic flowmeters of different diameters. Since the amplitude of the measurement signal of the electromagnetic flowmeter is very small, a high multiple amplifier is required, and the passband of the front and rear stage amplifiers is consistent in the traditional electromagnetic flowmeter, which will cause the output signal of the rear stage amplifier to be coupled to the front stage, which is very easy to cause the self-excitation of the amplifier. The present application can fully utilize the advantage of "ultra-high frequency resonance excitation", and the excitation resonance frequency is as high as 1Mhz or even higher, so the front stage amplifier and the rear stage amplifier can be used in a way that they are not in the same passband to realize signal isolation, and the self-excitation can be effectively avoided.

[0059] Preferably, the front stage adopts a passband amplifier, and the center frequency can be determined according to the selected excitation resonance frequency, and the front and rear selection 0.25 - 0.5Mhz bandwidth (preferred value), the front stage amplification multiple is preferably in the range of: 100 - 250 times, which is very easy to integrate into a circuit, and stable amplification can be obtained.

[0060] Preferably, the rear stage adopts a low pass filter, and the turning frequency is selected to be about 50Khz, which is very different from the high frequency passband of the front stage, so there will be no coupling between the front and rear stages, even if the total amplification multiple exceeds 100,000, there will be no self-excitation, and the principle is similar to that of a superheterodyne radio receiver.

[0061] The unique amplifier structure of the utility model determines that the utility model can obtain accurate flow measurement. In the signal amplification circuit involved in the utility model, different frequency bands are adopted for the front-stage amplifier and the rear-stage amplifier, and the advantage of this is that the front-stage signal and the rear-stage signal will not be coupled, and self-excitation is avoided, and for the purpose, a signal synchronous detection conversion circuit is inserted between the front-stage amplifier and the rear-stage amplifier. The utility model utilizes the synchronous relationship between the excitation resonance signal and the measurement signal, integrates the excitation resonance signal into a square wave as the "synchronous signal" of synchronous detection, and is used for controlling the opening action of the detection MOS bridge circuit. The advantage of this is that the synchronous conduction of the MOS is utilized to realize accurate detection.

[0062] 3. Special chip design

[0063] The utility model relates to a kind of ultrahigh frequency resonance excitation low-power consumption electromagnetic flowmeter, and its advantages are: first, through ultrahigh frequency resonance excitation, excitation power consumption can be greatly reduced, and drive circuit only needs to provide an initial excitation current, and subsequent signal measurement can be completed using the resonance of excitation coil and capacitor, which is the key to realize low power consumption;Second, using the characteristics of ultrahigh frequency excitation, the amplification circuit of measurement signal can be divided into: high-frequency passband amplification of front stage and low-pass amplification of rear stage, with synchronous detection conversion inserted in between, which can obtain stable high gain and improve measurement accuracy.

[0064] However, the above-mentioned circuit is relatively complex and has high cost, and a more appropriate method is to design a special chip.

[0065] According to the unique structure of the utility model: excitation processing and signal processing are on both sides of the measurement pipeline, and each occupies one side, and the advantage of this design is that strong excitation resonance current is limited on excitation processing PCB, and signal processing PCB is placed separately, which effectively avoids resonance current interference with measurement signal.

[0066] Therefore, the special chip can be divided into two according to function: excitation drive and synchronous signal generation chip, signal processing and flow generation chip.

[0067] (1) excitation drive and synchronous signal generation chip

[0068] For example Figure 10As shown, L1 is the excitation winding inductance, C1 is the resonance capacitor, Cx is the distributed capacitance of N1N2. N1N2 is N-channel MOS tube, two tubes are inversely connected into a bidirectional analog switch structure, preferably using SiC MOS, which has the advantages of high withstand voltage, small loss. T1 is an analog switch driving coupling transformer, the coupling pulse width is 5 - 20uS. C2C3L2C4C5 constitute a power filter circuit, which can effectively isolate the excitation resonance current from the power supply. The excitation drive and synchronization signal generation chip integrates a pulse transformer driver and an excitation resonance signal shaping circuit inside. The pulse transformer driver is used to amplify the input excitation signal to the power that can drive the pulse transformer; the excitation resonance signal shaping circuit is used to shape the excitation resonance signal into a square wave as the "synchronization signal" for signal detection and conversion of the electromagnetic flowmeter.

[0069] (2) Electromagnetic flowmeter signal processing and flow generation chip

[0070] The measurement electrode output signal of the electromagnetic flowmeter is a high-frequency signal synchronized with the excitation resonance signal, and the signal amplitude is very small, and the expected signal voltage is only: 1.176uV - 0.47mV, so 5000 - 10000 times amplification is required to perform ADC sampling, thereby completing subsequent flow calculation. However, high-multiple amplification circuits are very easy to self-excite, resulting in signal amplification failure. To solve this problem, the utility model adopts the method of connecting a front-stage high-frequency bandpass amplifier and a rear-stage low-pass amplifier in series, and inserting a detection conversion in the middle, which effectively avoids self-excitation.

[0071] After the original signal is amplified by the front-stage amplifier and then subjected to synchronous detection, it becomes a direct current pulse signal with a width of about 100 excitation resonance periods, and the width is preferably 50 - 100 excitation signal periods, so that the passband of the front-stage and rear-stage amplifiers can be effectively distinguished, and self-excitation is not easy. If the direct current pulse width is too narrow, the passbands of the front-stage and rear-stage amplifiers will overlap, and self-excitation is easy. If the direct current pulse width is too wide, the signal processing time will be too long, and ultimately the circuit power consumption will be too large. Therefore, 100 excitation resonance periods are preferred.

[0072] In the excitation and signal measurement process of the electromagnetic flowmeter involved in the utility model, the problem of temperature influence will occur, for example: under the condition that the excitation drive pulse width is the same, the temperature will cause the resistance of the analog switch and the coil resistance to change, and under the same pulse width, the obtained excitation current is inconsistent, which will cause measurement error. To overcome the influence of temperature on measurement accuracy, the electromagnetic flowmeter signal processing and flow generation chip needs to have a temperature compensation function inside.

[0073] The built-in PN junction temperature measurement signal conditioning circuit is used to realize the current temperature measurement of the flowmeter, and realizes the temperature correction of the flow under the cooperation of the single-chip microcomputer program.

[0074] The chip built-in measurement signal processing circuit is composed of a front-stage passband amplifier, a detection conversion and a rear-stage low-pass amplifier, the input original signal is an electrode signal of the electromagnetic flowmeter, a synchronous signal is shaped from a waveform of the excitation resonance circuit, and the synchronous signal is used for controlling the detection action of the synchronous bridge circuit; the chip built-in single-chip microcomputer kernel contains a high-speed ADC, a program data memory and a communication interface, the high-speed ADC is used for measuring temperature and flow signals, the communication interface is used for realizing function configuration and outputting flow data, and the single-chip microcomputer kernel provides work management of the special chip, including work parameter configuration, flow temperature adjustment and excitation signal generation action.

[0075] The utility model discloses the beneficial effect is:

[0076] 1、With the comparison of traditional electromagnetic flowmeter and the good effect of the utility model

[0077] The utility model relates to the superhigh frequency resonance excitation low -power consumption electromagnetic flowmeter, and its basic principle is just: through the free oscillation of LC resonance loop, only need a charging pulse, then can utilize the resonance and obtain longer time's repeated excitation, thereby obtain longer measurement time, and realize the purpose of super -low power consumption.

[0078] In order to achieve this purpose, the inventor installs the excitation coil in the middle of the measuring pipeline away from the metal parts from the structure, which can avoid the high-frequency electromagnetic field being absorbed by the metal parts, thereby obtaining higher Q value. The excitation coil of the traditional electromagnetic flowmeter is placed outside the pipeline, although the waterproof of the excitation coil is more easy, but the excitation coil is close to the magnetic shielding layer to obtain the electromagnetic field generated by the external metal pipeline coil excitation, which will be absorbed by the metal parts, therefore, the electromagnetic flowmeter of the traditional structure cannot adopt the "superhigh frequency resonance excitation" of the utility model.

[0079] Meanwhile, the inventor preferably adopts SiC MOS to realize bidirectional analog switch driving of the excitation coil, the SiC MOS has very small loss, and the bidirectional blocking effect of the bidirectional analog switch is utilized, so that the resonant circuit can obtain high Q value. The traditional electromagnetic flowmeter adopts bidirectional direct current pulse excitation, so that the excitation driving of the bidirectional analog switch structure is not needed, the bidirectional direct current pulse excitation has the advantages that stable excitation current can be obtained, but has the disadvantages that the magnetic force cycle is long and the power consumption is large. The utility model adopts high-voltage and high-current bidirectional analog switch driving of excitation, the resonant effect of the coil and the resonant capacitor is utilized to provide longer signal measurement time, and the resonant effect of the LC loop is utilized, so that the power supply is not needed during measurement, so that the purpose of reducing power consumption is achieved, and the excitation power consumption of the utility model can be reduced to below 15uA. The utility model preferably adopts the bidirectional analog switch composed of SiC MOS as the excitation driving, the purpose is to reduce the consumption of the switch device during resonant excitation, and to improve the Q value of the resonant excitation LC loop, which is an important advantage of the utility model. Of course, ordinary Si MOS with low switching efficiency can also be adopted, but the effect is poor and cannot be used as an excuse to bypass the utility model.

[0080] Meanwhile, since the measured signal is very weak, the inventor fully utilizes the characteristics that the output signal is synchronous with the excitation resonance and the super high frequency resonant excitation, inserts a detection conversion in the middle of the amplifier, divides the passband of the front-stage amplifier and the rear-stage amplifier, so that the front and rear coupling is avoided, self-excitation is avoided, and a high stable amplifier is obtained. The traditional electromagnetic flowmeter adopts a direct amplification circuit structure, the signal bandwidth between the front-stage and the rear-stage is consistent, so that self-excitation is very easy to occur, and the measurement error is large. The utility model can obtain stable amplification of up to 1-100,000 times, and the measurement precision is higher.

[0081] Meanwhile, considering that the excitation and the absorption of electromagnetic waves by the surrounding material will change with temperature, the inventor adopts temperature adjustment to realize flow-temperature compensation, so that high precision can be obtained in the whole temperature range.

[0082] Through the above technical measures, the following good effects are obtained:

[0083] Firstly, the average power consumption of the electromagnetic flowmeter is 13-15uA when the flowmeter measures once per second;

[0084] Secondly, the minimum measurement flow rate is 5-8mm / S, the minimum flow rate reaches 4.5-7.2L / H when converted to DN15 pipeline, the maximum flow rate is calculated according to 3000L / H, and the range ratio reaches 416-666.

[0085] 2, Comparison with ultrasonic flowmeter

[0086] With the development of intelligent metering instrument, water meter manufacturers in the global range are seeking the full electronic road of intelligent water meter, and the peers at home and abroad have made a lot of efforts for this purpose, and the most concerned scheme at present is: ultrasonic flowmeter water meter, but the ultrasonic flowmeter adopts piezoelectric ceramic transducer, and the piezoelectric ceramic is relatively fragile, and when encountering strong vibration and long-term high and low temperature aging, the piezoelectric ceramic will appear internal delamination fracture fault, and lose the metering function, at the same time, the mud in the water will continuously deposit on the surface of the transducer, causing the transducer mismatch, thereby causing large measurement error. For a long time, the industry has always believed that the electromagnetic flowmeter is a more noise-resistant, more accurate and more stable flow measurement method, but for a long time, the electromagnetic flowmeter needs a larger current for excitation, so the power consumption is large, and therefore it cannot be used for full electronic small caliber water meter.

[0087] And the utility model discloses the low power consumption of electromagnetic flowmeter is realized by adopting ultrahigh frequency resonance excitation, and the stable high amplification of special signal processing method is realized, thereby realizing low power consumption without losing precision, even obtaining higher measurement precision. Therefore, the utility model opens the new era of full electronic water meter, and has a great promoting effect on the development of water meter and flowmeter in the global range. BRIEF DESCRIPTION OF DRAWINGS

[0088] Figure 1 It is the whole installation structure schematic diagram of the utility model's ultrahigh frequency resonance excitation low power consumption electromagnetic flowmeter;

[0089] Figure 2 It is the utility model's Figure 1 It is the three-dimensional structure schematic diagram after removing the electrical processing shell and the metal pipeline;

[0090] Figure 3 It is the utility model's Figure 2 It is the three-dimensional structure schematic diagram after removing the magnetic shielding belt;

[0091] Figure 4 It is the three-dimensional structure schematic diagram of the sensor core support of the utility model;

[0092] Figure 5 It is the three-dimensional structure schematic diagram of the waterproof sensor core of the utility model;

[0093] Figure 6 It is the explosion drawing of the waterproof sensor core of the utility model;

[0094] Figure 7 It is the three-dimensional structure schematic diagram of the sensor core of the utility model;

[0095] Figure 8The utility model discloses a sensor core's one of multi -layer PCB excitation winding winding layout and measurement electrode pad and signal lead -out structure schematic drawing.

[0096] Figure 9 The utility model discloses a sensor core's another multi -layer PCB excitation winding winding layout and measurement electrode pad and signal lead -out structure schematic drawing.

[0097] Figure 10 The utility model discloses the function principle diagram of excitation drive and synchronous signal generation chip.

[0098] Figure 11 The utility model discloses electromagnetic flowmeter signal processing and flow generation chip block diagram.

[0099] Figure 12 The utility model discloses ultrahigh frequency resonance excitation circuit diagram.

[0100] Figure 13 The utility model discloses the circuit design drawing of reducing excitation resonance current to the interference of measurement signal.

[0101] Figure 14 The utility model discloses synchronous rectification (synchronous detection) circuit diagram.

[0102] In the drawing,

[0103] 1, sensor core, 2, sensor core waterproof box, 3, sensor core support, 4, inner lining pipe, 5, magnetic shielding tape, 6, downstream metal pipeline, 7, upstream metal pipeline, 8, screw, 101, multi -layer PCB, 102, signal lead -out ear, 103, measurement electrode, 201, sensor core box, 202, sensor core box cover, 203, electrode lead -out hole, 301, measurement pipeline, 302, sensor core waterproof box installation slot hole, 303, waterproof glue fills the cavity, 304, signal processing PCB installation cavity, 305, magnetic shielding tape winding limit slot, 306, sealing ring slot, 307, inner lining pipeline butt joint slot, 308, sealing ring, 501, first signal line lead -out hole, 701, electrical box installation bottom disc, 702, second signal line lead -out hole. DETAILED DESCRIPTION

[0104] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. The components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0105] Therefore, the following detailed description of embodiments of the application provided in the drawings is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.

[0106] Figures 1-14 For a specific embodiment of the application, the embodiment is a ultrahigh frequency resonance excitation magnetic low-power electromagnetic flowmeter, which realizes ultrahigh frequency resonance excitation and low-power design from the structure of the inventor, designs a sensor core supported by a PCB board, and obtains a waterproof sensor core after waterproof treatment, and further designs a sensor core support, which is essentially a measuring pipeline, and the waterproof sensor core is inserted into the middle of the sensor core support, and the waterproof sensor core divides the measuring pipeline into two parts.

[0107] The sensor core 1 is installed in the sensor core waterproof box 2, the sensor core waterproof box 2 is installed in the middle position of the sensor core support 3, the sensor core waterproof box 2 divides the measuring pipeline 301 in the sensor core support 3 into two parts, and the front and back surfaces of the sensor core support 3 are respectively provided with a signal processing PCB board and an excitation signal driving PCB board, and special chips are respectively arranged in the two PCB boards, and the sensor core support 3 is installed in a metal pipeline.

[0108] The sensor core 1 is an "integrated excitation winding and electrode" of an electromagnetic flowmeter excitation winding and a measurement electrode made of a multilayer PCB board 101. The multilayer PCB board 101 protrudes signal lead ears 102 at both ends. The excitation winding is arranged on the inner layer metal of the multilayer PCB board 101, and the measurement electrode 103 is arranged on the surface metal of the multilayer PCB board 101. The PCB has two surfaces, Top and Bottom. The measurement electrode 103 is manufactured on both the Top and Bottom layers. The two electrode signals are connected in series and then led out. The electrode welding pad is manufactured on the multilayer PCB board 101, and the measurement electrode 103 is welded on the electrode welding pad. The material of the measurement electrode 103 is corrosion-resistant metal or alloy, including stainless steel and hastelloy. The sensor core 1 is made of only a PCB to manufacture a measurement electrode lead-out pad and a lead-out circuit. The PCB board is used as a support, and the excitation coil is wound with enameled wire. In this case, the excitation coil is placed on the upper and lower surfaces of the PCB board.

[0109] Sensor core waterproof box 2 is made of plastic, including PPO or PPS, two electrode lead-out holes 203 are opened on sensor core box 201 and sensor core box cover 202, sensor core 1 is placed into sensor core box 201 and filled with epoxy resin potting glue; sensor core 1 is directly injection molded, sensor core 1 is used as an injection molding framework, and the outside is injection molded into the appearance of sensor core waterproof box 2.

[0110] Sensor core support 3 is made of plastic, including PA, PPO and PPS, sensor core support 3 is a cylindrical hollow pipe, the hollow pipe in the middle is a measuring pipe 301, signal processing PCB mounting cavities 304 are opened on two sides of sensor core support 3, electromagnetic flowmeter signal processing PCBs are installed in the two cavities, one of which is installed with excitation signal drive PCB, and the other is installed with measuring signal processing PCB; sensor core waterproof box mounting slot holes 302 with two circular arcs in the middle are opened in signal processing PCB mounting cavities 304, the slot holes pass through the upper and lower signal processing PCB mounting cavities 304, and sensor core waterproof box 2 is installed; waterproof glue potting cavities 303 are opened around sensor core waterproof box mounting slot holes 302, after sensor core waterproof box 2 is installed in place, epoxy resin sealant is filled in the cavity to achieve water and electricity isolation between measuring pipe 301 and electrical parts; magnetic shielding tape winding limiting grooves 305 are opened in the middle of the outer side of sensor core support 3, after sensor core waterproof box 2 and signal processing PCB, excitation signal drive PCB are installed in place, magnetic shielding tape 5 is wound in magnetic shielding tape winding limiting grooves 305, magnetic shielding tape 5 is made of permalloy or pure iron or silicon steel strip, the thickness of the strip is 0.05-0.1mm, and multiple layers are wound to form external magnetic shielding, the winding thickness is 0.5mm, first signal line lead-out holes 501 are opened on magnetic shielding tape 5, and electromagnetic flowmeter power supply and signal output are led out to the outside.

[0111] Sensor core support 3 is inserted with inner lining pipe 4 on both sides, which plays the role of electrical signal insulation, preventing water flow from contacting the metal pipe wall to cause signal short circuit. Inner lining pipe 4 is made of plastic and is inserted into the inner lining pipe butt joint groove 307 of sensor core support 3 by using coating adhesive. Two top surfaces of sensor core support 3 are provided with sealing ring groove 306 for installing sealing ring 308 to prevent water flow from bypassing into the electrical signal cavity through the gap between the metal pipe and inner lining pipe 4. Metal pipe is sleeved outside inner lining pipe 4 and is divided into downstream metal pipe 6 and upstream metal pipe 7. Upstream refers to the direction of water flow. Second signal line lead-out hole 702 and electrical box mounting bottom plate 701 with screw hole are arranged on upstream metal pipe 7. Downstream and upstream metal pipes are fixed by screw 8 or are threadedly connected. The plane of sensor core waterproof box 2 is perpendicular to the plane of electrical box mounting bottom plate 701, that is, in the vertical direction, sensor core waterproof box 2 divides water flow into left and right two subflows, which can reduce the deposition of impurities in water flow on the surface of measuring electrode 103, improve the anti-pollution ability and prolong the service life. Sealant can be coated between the metal pipe and inner lining pipe 4.

[0112] The purpose of the inventor in adopting such an electromagnetic flow measurement structure is:

[0113] Firstly, the excitation coil is placed in the middle of the measuring pipe, away from the metal parts (magnetic shielding belt and metal pipe parts), to prevent the high-frequency electromagnetic field from being absorbed by the metal and causing the Q value of the resonant excitation to be too low. Therefore, placing the waterproof sensor core in the middle of the measuring pipe is the key to realizing the "ultra-high frequency resonant excitation" of the present application. The physical principle is that the eddy current effect of the high-frequency electromagnetic field can be effectively avoided by the structure adopted by the present application, thereby improving the Q value of the excitation resonant circuit. Under the condition of adopting a PCB excitation coil, the inventor can obtain a Q value of about 65, and under the condition of adopting an enameled wire excitation coil, a Q value of about 620 can be obtained.

[0114] Secondly, the measuring electrode is divided into positive and negative two surfaces, and the electrode signals of the two surfaces can be connected in series. In this way, the amplitude of the measurement signal is doubled, the sensitivity is improved, and the measurement accuracy is improved.

[0115] Further, a magnetic shielding belt winding groove is designed on the sensor core support, and a magnetic shielding belt with a thickness of 0.4-0.5 mm can be wound on the sensor core. This magnetic shielding belt protects the signal processing circuit of the electromagnetic flowmeter inside, which can effectively avoid external signal interference, and also forms a stable magnetic space to prevent external magnetic materials from affecting the excitation magnetic field.

[0116] Further, the inventors design a lining pipe pair insertion slot and a sealing ring slot on the sensor core support, the lining pipe pair insertion slot can insert a lining pipe to form an insulation layer to prevent the metal pipe from short circuiting the measurement signal, and the sealing ring slot can accommodate a sealing ring to isolate the gap between the metal pipe and the lining pipe from water leakage.

[0117] Further, the inventors adopt a unique bidirectional analog switch driven excitation drive and resonance circuit, the bidirectional analog switch preferably adopts N-channel SiC MOS in reverse series, the SiC MOS has the advantages of small parasitic capacitance and low leakage, and the excitation resonance circuit has a high Q value. The high-frequency resonance excitation is the most critical technical link of the utility model, and its effect is that only a short time of current opening is needed to realize long-time measurement by using the resonance circuit, and the power consumption is greatly reduced. The principle is that in the excitation charging stage: L * di / dt = Vbat, which is the inductance transient equation, wherein L is the inductance of the excitation coil, di is the current increment, dt is the time increment, and Vbat is the power supply voltage. The inventors wind a 32-turn coil with enameled wire, obtain an excitation coil with an area of 2.75cm 2 , an inductance of about 21.6uH, and a direct current resistance of 0.16 ohm. The above data is substituted into the inductance transient equation, and the current increment is set to 2A and the power supply voltage is selected to be 3.6V. The excitation charging time dt required can be calculated to be 12uS, and if the measurement is performed once per second, the average current Ip is 0.5 * 2A * 12uS / 1S = 12uA.

[0118] The reason why the utility model obtains the low power consumption effect is that the resonance loop composed of the excitation coil and the resonance capacitor has a high Q value, and only an excitation charging is needed to realize subsequent signal measurement under the free oscillation of the resonance loop. The inventors wind a coil with enameled wire, and the actual measured resonance Q value in the pipe reaches 620, and a very stable test effect is obtained, and the excitation power consumption is only 12uA.

[0119] Further, since the original output signal of the electromagnetic flowmeter is small, approximately 1.176uV-0.47mV is estimated, and 5000-10000 times amplification is required for ADC sampling, in the traditional electromagnetic flowmeter design, a direct amplification circuit is adopted, and under such high multiplication gain, the amplifier is very easy to be self-excited. In the utility model, the inventor ingeniously utilizes the frequency band difference between the super high frequency excitation and the effective signal, and divides the amplifier into high frequency passband amplification and low pass amplification two stages, since the passbands of the front and rear stage amplifiers are far apart, therefore, the front and rear coupling is avoided, and self-excitation is avoided, and the detection conversion is inserted between the front and rear stage amplifiers. Such amplifier structure can allow the amplification to reach more than 20000-100000, which has great significance for improving the measurement precision. Moreover, the inventor fully utilizes the electromagnetic induction law characteristic U=BLV, and there is a strict synchronization relationship between the measurement signal U and B, the excitation resonance signal is shaped into a square wave, as a synchronous detection control signal, and the switching action of the detection bridge is controlled, which is a key technical measure for realizing the detection conversion, and has good innovation and practicality.

[0120] Further, the utility model preferably adopts 50-100 times excitation resonance cycle time to collect the flow signal, and the purpose of this is to make the original signal and the signal bandwidth after detection change by 50-100 times, and the passbands of the front and rear stage amplifiers are fully isolated, which is the best scheme for obtaining high times stable amplifier, and is one of the best innovative points of the utility model.

[0121] According to 100 times excitation resonance cycle calculation, according to the resonance frequency 1Mhz calculation, the signal processing time is 100uS, according to the full opening of the measurement circuit function, the average power consumption is 10mA, and the signal processing average power consumption is 0.1mS*10mA / 1S=1uA. Considering that the excitation average power consumption is 12uA, therefore, the average power consumption of the super high frequency resonance excitation low power consumption electromagnetic flowmeter involved in the utility model is predicted to be 13-15uA.

[0122] Further, the super high frequency resonance excitation low power consumption electromagnetic flowmeter involved in the utility model has higher design difficulty in excitation driving, excitation resonance shaping, front stage signal amplification, synchronous detection, rear stage signal amplification, flow temperature compensation and the like circuit, therefore, in order to better realize the utility model, the preferred scheme is to design two special chips, one of which is an excitation driving and synchronous signal generation chip, and the other is an electromagnetic flowmeter signal processing and flow generation chip. The functions and working principles of the two chips have been described above, and will not be repeated here.

[0123] Finally, it is explained that the above embodiments are only used to illustrate the technical solutions of the present application and are not limited, and other modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art should be covered in the scope of the claims of the present application, as long as they do not deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A dedicated chip for a super-high frequency resonant excitation low-power electromagnetic flowmeter, two of which are installed in an excitation signal driving PCB board and a measurement signal processing PCB board respectively, characterized in that: the dedicated chip installed in the excitation signal driving PCB board is an excitation driving and synchronization signal generating chip, which internally integrates a pulse transformer driver and an excitation resonant signal shaping circuit; the pulse transformer driver is used to amplify the input excitation signal to a power that can drive the pulse transformer; and the excitation resonant signal shaping circuit is used to shape the excitation resonant signal into a square wave as a "synchronization signal" for signal detection conversion of the electromagnetic flowmeter; and the dedicated chip installed in the measurement signal processing PCB board is an electromagnetic flowmeter signal processing and flow information generating chip, which internally integrates a PN junction temperature measurement conditioning circuit, a measurement signal conditioning circuit, and a single-chip microcomputer kernel; the PN junction temperature measurement conditioning circuit is used to realize current temperature measurement of the flowmeter; the measurement signal conditioning circuit comprises a pre-stage passband amplifier, a detection conversion, and a post-stage low-pass amplifier, and the detection conversion is realized by using a synchronous rectification circuit; and the single-chip microcomputer kernel provides work management of the dedicated chip, including work parameter configuration, flow temperature adjustment, and excitation signal generation action. 2.The dedicated chip for a super-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 1, characterized in that: the excitation driving and synchronization signal generating chip comprises a circuit for realizing excitation driving by using a high-voltage analog switch, N1 and N2 are connected in reverse series to form a bidirectional analog switch, which blocks forward signals or blocks reverse signals when the analog switch is off, and an excitation inductor L1 and a resonant capacitor C1 form an LC free resonant circuit; N1 and N2 are SiC MOS tubes or GaN MOS tubes or Si MOS tubes. 3.The dedicated chip for a super-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 1, characterized in that: the excitation driving and synchronization signal generating chip comprises a circuit for reducing interference of excitation resonant current on measurement signals, C2 and C3 are power filter capacitors, L1, C1, and Cx form a resonant circuit, and Cx is a distributed capacitor of the analog switch. 4.The dedicated chip for a super-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 1, characterized in that: in the measurement signal conditioning circuit, the center frequency of the pre-stage passband amplifier is determined according to the selected excitation resonant frequency, and the bandwidth of 0.25-0.5 Mhz is selected before and after the pre-stage amplifier, and the pre-stage amplification range is 100-250 times; the turning frequency of the post-stage low-pass amplifier is 50 Khz; and a signal detection conversion circuit is inserted between the pre-stage amplifier and the post-stage amplifier. 5.A super-high frequency resonant excitation low-power electromagnetic flowmeter comprising a sensor core (1), characterized in that: ​ ​ ​ ​ ​ ​ The sensor core (1) is installed in the sensor core waterproof box (2), the sensor core waterproof box (2) is installed in the middle position of the sensor core support (3), the sensor core waterproof box (2) divides the measuring pipe (301) in the sensor core support (3) into two parts, the front and back of the sensor core support (3) are respectively provided with a signal processing PCB and an excitation signal driving PCB, the two PCBs are respectively provided with the special chip as claimed in claim 1, and the sensor core support (3) is installed in a metal pipe.

6. The ultra-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 5, characterized in that: The sensor core (1) is an integrated excitation winding and electrode for electromagnetic flowmeter excitation winding and measuring electrode, which is manufactured by using a multilayer PCB (101), signal lead ears (102) are protruded from both ends of the multilayer PCB (101), the excitation winding is arranged on the inner metal layer of the multilayer PCB (101), the measuring electrode (103) is arranged on the surface metal layer of the multilayer PCB (101), the PCB has two surfaces, Top and Bottom, the measuring electrode (103) is manufactured on both the Top and Bottom surfaces, and the two electrode signals are connected in series and then led out; the electrode welding Pad is manufactured on the multilayer PCB (101), the measuring electrode (103) is welded on the electrode welding Pad, and the material of the measuring electrode (103) is corrosion-resistant metal or alloy; the sensor core (1) is manufactured by using only the PCB to manufacture the measuring electrode lead-out Pad and lead-out circuit, the PCB is used as support, and the excitation coil is wound by using enameled wire, and the excitation coil is arranged on the upper and lower surfaces of the PCB.

7. The ultra-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 5, characterized in that: The sensor core waterproof box (2) is manufactured by using plastic, including PPO or PPS, two electrode lead-out holes (203) are formed in the sensor core box (201) and the sensor core box cover (202), and epoxy resin potting glue is filled after the sensor core (1) is placed into the sensor core box (201); the sensor core (1) is directly injection molded, the sensor core (1) is used as an injection molding framework, and the sensor core (1) is injection molded into the appearance of the sensor core waterproof box (2).

8. The ultra-high frequency resonant excitation low-power electromagnetic flowmeter according to claim 5, characterized in that: The sensor core support (3) is made of plastic, and the sensor core support (3) is a cylindrical hollow pipe, the hollow pipe in the middle is a measuring pipe (301), signal processing PCB board installation cavities (304) are formed on two sides of the sensor core support (3), electromagnetic flowmeter signal processing PCB boards are installed in the two cavities, one of the two cavities is provided with an excitation signal driving PCB board, and the other is provided with a measuring signal processing PCB board; a sensor core waterproof box installation slot hole (302) with two arc sides is formed in the middle of the signal processing PCB board installation cavity (304), the slot hole penetrates through the upper and lower signal processing PCB board installation cavities (304), and a sensor core waterproof box (2) is installed in the slot hole; a waterproof glue pouring cavity (303) is formed around the sensor core waterproof box installation slot hole (302); a magnetic shielding band winding limiting slot (305) is formed in the middle of the outer side of the sensor core support (3), a magnetic shielding band (5) is wound in the magnetic shielding band winding limiting slot (305), the magnetic shielding band (5) is made of permalloy or pure iron or silicon steel strip material, the thickness of the strip material is 0.05-0.1 mm, and the magnetic shielding band is wound in multiple layers to form external magnetic shielding, the winding thickness is 0.5 mm, and a first signal line lead-out hole (501) is formed in the magnetic shielding band (5), so that the power supply and signal output of the electromagnetic flowmeter are output to the outside.

9. The ultra-high frequency resonant excitation magnetic low-power electromagnetic flowmeter according to claim 8, characterized in that: An inner lining pipe (4) is inserted into each of the upper and lower sensor core supports (3), the inner lining pipe (4) is made of plastic, and the inner lining pipe is inserted into an inner lining pipe butt joint groove (307) of the sensor core support (3) by using a coating adhesive; sealing ring grooves (306) are formed on two top surfaces of the sensor core support (3), and are used for installing sealing rings (308); a metal pipe is sleeved outside the inner lining pipe (4), and is divided into a downstream metal pipe (6) and an upstream metal pipe (7), the upstream metal pipe (7) is provided with a second signal line lead-out hole (702) and an electrical box mounting bottom plate (701) with screw holes, and the upstream and downstream metal pipes are fixed by screws (8) or are threadedly butted; a plane of the sensor core waterproof box (2) is perpendicular to a plane of the electrical box mounting bottom plate (701); and the metal pipe and the inner lining pipe (4) can be coated with sealant.

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