CN-122015988-A - Self-adaptive signal amplifying and filtering circuit of electromagnetic flowmeter

CN122015988ACN 122015988 ACN122015988 ACN 122015988ACN-122015988-A

Abstract

The invention belongs to the technical field of circuits, and particularly relates to a self-adaptive signal amplifying and filtering circuit of an electromagnetic flowmeter, which comprises a signal acquisition module, a photoelectric isolation module, a self-adaptive gain amplifying module, a self-adaptive filtering module, a signal output module and a stable power supply module for supplying power to each module, wherein the self-adaptive gain amplifying module is in bidirectional communication with the self-adaptive filtering module, and the stable power supply module is also connected with the self-adaptive gain amplifying module. The invention effectively solves the problems of poor measurement adaptability and insufficient stability caused by the split of the signal processing link and no linkage among modules of the traditional electromagnetic flowmeter by constructing the sequential connection structure of the signal acquisition module, the photoelectric isolation module, the self-adaptive gain amplification module, the self-adaptive filtering module and the signal output module and matching the cooperative design of the stable power module and the self-adaptive gain amplification module and the self-adaptive filtering module.

Inventors

ZHANG RUI
HAN ZIJIAN
HAN LEI
ZHANG ZHI

Assignees

南京迈岳科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (7)

1. The self-adaptive signal amplifying and filtering circuit of the electromagnetic flowmeter is characterized by comprising a signal acquisition module, a photoelectric isolation module, a self-adaptive gain amplifying module, a self-adaptive filtering module, a signal output module and a stable power supply module for supplying power to each module, wherein the self-adaptive gain amplifying module is in bidirectional communication with the self-adaptive filtering module, and the stable power supply module is also connected with the self-adaptive gain amplifying module.
2. The self-adaptive signal amplifying and filtering circuit of the electromagnetic flowmeter according to claim 1, wherein the signal collecting module comprises a precise instrument operational amplifier and current limiting resistors R1 and R2, one end of the current limiting resistor R1 is used for being connected with a positive differential output end of an electromagnetic flowmeter sensor, the other end of the current limiting resistor R1 is connected with a non-inverting input end of the precise instrument operational amplifier, one end of the current limiting resistor R2 is used for being connected with a negative differential output end of the electromagnetic flowmeter sensor, the other end of the current limiting resistor R2 is connected with an inverting input end of the precise instrument operational amplifier, a power supply input end of the precise instrument operational amplifier is connected with a power supply output end of the stable power supply module, and an output end of the precise instrument operational amplifier is connected with an input end of the photoelectric isolation module and is used for primarily conditioning differential weak signals output by the sensor and then transmitting the differential weak signals to the photoelectric isolation module.
3. The self-adaptive signal amplifying and filtering circuit of the electromagnetic flowmeter according to claim 1, wherein the photoelectric isolation module comprises a photoelectric coupler U1 and current limiting resistors R3 and R4, the photoelectric coupler U1 comprises a light emitting diode and a phototriode which are mutually coupled, an anode of the light emitting diode is connected with an output end of the signal acquisition module through the current limiting resistor R3, a cathode of the light emitting diode is grounded, a collector of the phototriode is connected with a power supply output end of the stable power supply module through the current limiting resistor R4, an emitter of the phototriode is grounded, and a collector of the phototriode is used as an output end of the photoelectric isolation module and is connected with a signal input end of the self-adaptive gain amplifying module.
4. The self-adaptive signal amplifying and filtering circuit according to claim 1, wherein the self-adaptive gain amplifying module comprises a gain adjusting unit, a signal amplitude detecting unit and a control unit, wherein the gain adjusting unit comprises a triode Q1, a base coupling resistor R5, a voltage dividing resistor network, a controllable voltage divider and an accelerating capacitor C1, the base of the triode Q1 is connected with the output end of the photoelectric isolation module through the base coupling resistor R5, the accelerating capacitor C1 is connected in parallel with the two ends of the base coupling resistor R5, the power supply end of the voltage dividing resistor network is connected with the power supply output end of the stable power supply module, the pull-up voltage dividing arm end of the voltage dividing resistor network is connected with the collector of the triode Q1 through a voltage dividing resistor R6, the pull-down voltage dividing arm end of the voltage dividing resistor network is connected with one end of the controllable voltage dividing element, the other end of the controllable voltage dividing element is connected with the emitter of the triode Q1, the signal input end of the signal amplitude detecting unit is connected with the output end of the triode Q1, the signal amplitude detecting unit is connected with the signal input end of the voltage dividing resistor, the signal amplitude detecting unit is connected with the feedback control unit is connected with the power supply end of the voltage dividing element, the self-adaptive voltage dividing resistor is connected with the power supply module, the signal amplitude adjusting unit is connected with the power supply end of the self-adaptive voltage dividing element is connected with the power supply end, and realizing gain self-adaptive adjustment.
5. The adaptive signal amplification and filtering circuit of an electromagnetic flowmeter according to claim 1, wherein the adaptive filtering module comprises a main branch and a coupling branch, an input end of the main branch is connected with a signal output end of the adaptive gain amplification module, the main branch is sequentially connected with a 2-out-of-1 switch A, a high-pass filter, a 2-out-of-1 switch B, a band-stop filter and a 2-out-of-1 switch C in series, the other input end of the 2-out-of-1 switch A is a through path, the other input end of the 2-out-of-1 switch B is a through path, the other input end of the 2-out-of-1 switch C is a through path, an output end of the 2-out-of-1 switch C is connected with an input end of the signal output module, an input end of the coupling branch is connected with an input end of the 2-out-1 switch A in the main branch, an output end of the coupling branch is connected with an input end of the band-pass filter A, an output end of the band-pass filter A, B is connected with an input end of the high-pass filter C, the power supply end of the high-speed detector circuit is connected with an input end of the main-out-1 switch B, the high-speed detector circuit is connected with an output end of the main-out-of the power supply module, and the high-speed detector circuit is connected with an output of the 2-out-of the main 1 switch C is used as a stable signal, and the adaptive signal is connected with an adaptive signal of the adaptive gain amplification module according to the type 1, and the adaptive signal is controlled by the adaptive signal output module, and the adaptive signal is controlled by the adaptive signal input of the adaptive signal amplification module.
6. The self-adaptive signal amplifying and filtering circuit of the electromagnetic flowmeter according to claim 1, wherein the stable power supply module comprises a linear stable power supply, a power supply voltage detection circuit and a voltage division adjustment circuit, wherein the input end of the voltage division adjustment circuit is used for being connected with an industrial direct current power supply, the output end of the voltage division adjustment circuit is connected with the input end of the linear stable power supply, the detection input end of the power supply voltage detection circuit is connected with the input end of the voltage division adjustment circuit, the output end of the power supply voltage detection circuit is connected with the control end of the voltage division adjustment circuit, the voltage division ratio of the voltage division adjustment circuit is controlled according to the voltage fluctuation of the industrial direct current power supply, the voltage stability of the voltage inputted to the linear stable power supply is ensured, the output end of the linear stable power supply is divided into a general power supply output end and a special power supply output end, the general power supply output end is connected with the power supply input end of the control unit of the self-adaptive gain module, the self-adaptive filter module and the signal output module, and the special power supply output end is the stable direct current power supply voltage.
7. The self-adaptive signal amplifying and filtering circuit of the electromagnetic flowmeter according to claim 1, wherein the signal output module comprises a buffer operational amplifier and an output current limiting resistor R7, wherein the in-phase input end of the buffer operational amplifier is connected with the main branch output end of the self-adaptive filtering module, the anti-phase input end of the buffer operational amplifier is directly short-circuited with the self-output end to form a voltage follower, the power supply input end of the buffer operational amplifier is connected with the general power supply output end of the stable power supply module, and the output end of the buffer operational amplifier is used as a signal output end through the output current limiting resistor R7 and is used for being in butt joint with a display unit or a control unit of the electromagnetic flowmeter to realize signal output after impedance matching.

Description

Self-adaptive signal amplifying and filtering circuit of electromagnetic flowmeter Technical Field The invention belongs to the technical field of circuits, and particularly relates to a self-adaptive signal amplifying and filtering circuit of an electromagnetic flowmeter. Background Electromagnetic flowmeter is used as flow measuring equipment based on electromagnetic induction principle, and has the advantages of no throttling component, wide measuring range, strong adaptability and the like, and is widely applied to the industrial fields of chemical industry, water treatment, metallurgy, petroleum and the like, and is used for monitoring the flow of conductive media (such as acid-base solution, sewage, slurry and the like). The core working principle is that alternating magnetic fields are applied to two sides of a measuring pipeline, so that a conductive medium flowing through the pipeline cuts magnetic lines to generate induced electromotive force, the induced electromotive force is converted into an electric signal by a sensor and output, and the electric signal is conditioned by a signal processing circuit and finally converted into a corresponding flow value. However, complex working conditions (such as strong electromagnetic interference, fluctuation of power supply voltage, large span of medium flow speed, etc.) in the industrial field bring a plurality of technical challenges to signal processing of the electromagnetic flowmeter. The induction electric signal output by the sensor has obvious weak property (usually millivolt level), dynamic fluctuation (the signal amplitude greatly fluctuates along with the change of the flow speed and concentration of the medium), the signal strength can be lower than 1mV at low flow rate and can be raised to more than 1V at high flow rate), and the induction electric signal is easy to be interfered (easily influenced by industrial common interference such as power frequency interference (50 Hz/60 Hz), electromagnetic coupling interference, ground loop interference and the like), so that stringent requirements are provided for the suitability, anti-interference capability and stability of the signal processing circuit. The signal processing circuit of the existing electromagnetic flowmeter still has the following prominent problems in practical application: the gain adaptability is poor, and a fixed gain amplification design is adopted for a plurality of circuits, so that the signal amplitude variation under different flow can not be matched dynamically. And at low flow, the weak signal is easily submerged by background noise, so that effective signal extraction is difficult, and at high flow, the strong signal is easily out of the linear working range of the circuit, saturation distortion is caused, and finally the full-range measurement accuracy is reduced. The anti-interference capability is insufficient, the existing filtering mechanism mostly adopts a filter with single fixed parameter (such as single high-pass filtering or band-stop filtering), the filtering channel is not switchable, and the response is lagged. In the face of complex and changeable interference (such as power frequency interference, harmonic interference, electromagnetic pulse interference generated by equipment start-stop and the like) on an industrial site, targeted and rapid inhibition cannot be realized, and an interference signal can be directly overlapped on an effective signal, so that fluctuation of measured data is large. The signal isolation design is deficient or imperfect, and when the industrial field-activated power equipment (such as a frequency converter, a motor, a pump body and the like) and the electromagnetic flowmeter are deployed in a short distance, the strong electric interference and the ground loop interference are easy to invade the core processing unit through a signal link. The existing partial circuits are not provided with isolation modules, or only simple resistor isolation is adopted, so that effective electrical isolation cannot be realized, and a signal link is polluted by interference, so that the measurement stability is affected. The power supply has weak adaptability, the industrial power supply system has the problems of voltage fluctuation (such as wide-range fluctuation of 12V-24V), voltage spike and the like, and the power supply module of the existing signal processing circuit is mostly simple in voltage stabilizing design and lacks self-adaptive adjustment capability. When the power supply voltage exceeds the rated range, the working parameters of core devices (such as an operational amplifier, a detector, an analog switch and the like) are easy to drift, even breakdown and damage are caused, and the circuit is unstable in working or is stopped. The module has poor cooperativity, that is, the functional modules of the existing circuit such as amplifying, filtering, power supply and the like are mostly designed independently, and a linkage mechan