CN216851928U - Solid-state switch automatic gain switching circuit of potentiometer for cathode protection measurement - Google Patents
Solid-state switch automatic gain switching circuit of potentiometer for cathode protection measurement Download PDFInfo
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- CN216851928U CN216851928U CN202123267680.8U CN202123267680U CN216851928U CN 216851928 U CN216851928 U CN 216851928U CN 202123267680 U CN202123267680 U CN 202123267680U CN 216851928 U CN216851928 U CN 216851928U
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Abstract
The utility model provides a solid-state switch automatic gain switching circuit of potentiometer for cathodic protection measurement, include: a fifth terminal DA and a sixth terminal DB of the analog switch U7 are respectively connected to an inverting input terminal of the first operational amplifier U5A, a control terminal GC _ S1 of the analog switch U7 receives an adjustment instruction, a forward input terminal of the first operational amplifier U5A is a circuit input terminal, an output terminal of the first operational amplifier U5A is connected to one terminal of the first low-temperature-drift precision resistor R4 and a forward input terminal of the second operational amplifier U5B, the other terminal of the first low-temperature-drift precision resistor R4 is connected to the first terminal S3A and the second terminal S3B of the analog switch and one terminal of the second low-temperature-drift precision resistor R9, the other terminal of the second low-temperature-drift precision resistor R9 is connected to the third terminal S4A and the fourth terminal S4B of the analog switch, and an output terminal of the second operational amplifier U5B outputs a driving signal.
Description
Technical Field
The utility model relates to a circuit calculation field especially relates to a solid state switch automatic gain switching circuit of potentiometer for cathodic protection measurement.
Background
One of the core works of corrosion prevention of the oil and gas long-distance buried steel pipeline is to continuously identify and evaluate various risk factors which face the pipeline and influence the cathode protection effectiveness of the pipeline to reach the standard, and continuously take action to control the corrosion of the pipe body within an acceptable range so as to ensure the production safety.
The pipeline penetrates through various geological and geomorphic environments in a long distance, the pipelines are crossed and parallel (the pipelines are mutually interfered), hidden danger problems occur in the construction period, and the running reliability of the underground construction system is reduced due to the complexity of the pipeline and the external environment; the method has the advantages that the method has the problems of external environment interference (high-voltage direct-current transmission lines, urban rail transit, industrial and mining enterprises, alternating-current electrified railways and high-voltage transmission lines), the number of stray current interference sources is large, the influence is superimposed, the harmfulness of the pipelines due to stray current interference and corrosion is strong, and the interference and corrosion risks of the pipelines are increased year by year; difficulties with cathodic protection maintenance management include: proper methods and equipment are lacked for correctly setting output parameters of the potentiostat, the effective demand of the cathode protection current cannot be effectively judged, the failure reason of the potentiostat is investigated, and a solution is difficult to put forward; the pipeline operation units develop evaluation which is divided into different categories, the investigation method is uneven, the investigation data support is insufficient, the judgment standard is not unified, the recognition of the interference hazard is not unified, and the recognition of the importance of the interference protection is not unified.
The technical means for solving the problems is that a direct current potential and an alternating current voltage of a measuring tube to the ground and alternating current and direct current flowing through a defect of an anticorrosive layer of a pipeline are measured through a potentiometer, a pipeline forced current cathode protection system, a polarization potential and the condition of interference of alternating current and direct current are periodically evaluated, special investigation is carried out on cathode protection electrical insulation/electrical continuity, facilities, a sacrificial anode, drainage facilities, a remote monitoring system and cathode protection effectiveness of a crossing pipeline, the running state of the pipeline cathode protection facilities is continuously concerned, and the problem is found and timely treated.
The existing metering apparatus comprises:
the utility model relates to a cathode protection potentiometer with static measuring range.
The cathode protection potentiometer with the manually switchable measuring range uses a mechanical relay or a switch to switch the measuring range.
When measuring voltage or current, firstly, evaluating the approximate range of a pre-measurement parameter, selecting and setting a relatively reasonable measuring range, then placing the portable potentiometer on the site for long-time (24h) monitoring, and finding the following problems in the measuring process:
because the pipeline distance is long, the external environment is complex, the potential levels of the pipelines in different intervals are inconsistent, the potential of the pipeline is between 0.5 volt and 2 volts when the pipeline is not interfered by the outside, once the potential is interfered by the outside and can reach dozens of volts or even hundreds of volts, the current value of the soil flowing through the defect point of the pipeline is different because of the resistivity of the soil near the defect point, the current can be in the level from microampere to dozens of milliamperes, and how to select a reasonable measuring range by the potentiometer directly influences the accuracy of the evaluation data.
Therefore, the existing metering apparatus has the following problems:
(1) in the cathodic protection measurement, the low voltage measurement precision is reduced due to the fixed wide range.
(2) When the range is adjusted manually, the range is difficult to determine, and a part of over-range data is invalid when long-time measurement is easy.
(3) The method of mechanically switching the range has the problems of difficulty in dynamically switching the range and high energy consumption.
(4) When the range is dynamically switched, the measurement data is unreliable due to frequent range switching.
SUMMERY OF THE UTILITY MODEL
The present invention is directed to a solid state switching automatic gain switching circuit for a potentiometer for cathodic protection measurement that overcomes or at least partially solves the above problems.
In order to achieve the above object, the technical solution of the present invention is specifically realized as follows:
an aspect of the utility model provides a solid-state switch automatic gain switching circuit of potentiometer for cathodic protection measurement, include: the circuit comprises an analog switch U7, a first operational amplifier U5A, a second operational amplifier U5B, a first low-temperature drift precision resistor R4 and a second low-temperature drift precision resistor R9; a fifth terminal DA and a sixth terminal DB of the analog switch U7 are respectively connected to an inverting input terminal of the first operational amplifier U5A, a control terminal GC _ S1 of the analog switch U7 receives an adjustment instruction, a forward input terminal of the first operational amplifier U5A is a circuit input terminal, an output terminal of the first operational amplifier U5A is connected to one terminal of the first low-temperature-drift precision resistor R4 and a forward input terminal of the second operational amplifier U5B, the other terminal of the first low-temperature-drift precision resistor R4 is connected to the first terminal S3A and the second terminal S3B of the analog switch and one terminal of the second low-temperature-drift precision resistor R9, the other terminal of the second low-temperature-drift precision resistor R9 is connected to the third terminal S4A and the fourth terminal S4B of the analog switch, and an output terminal of the second operational amplifier U5B outputs a driving signal.
Wherein, the circuit still includes: the clamp circuit comprises a third operational amplifier U3A, a first double diode D1 and a second double diode D2, wherein the forward input end of the third operational amplifier U3A is respectively connected with the input end of the first double diode D1, the output end of the second double diode D2 and the input end of the first operational amplifier U5A, the reverse input end of the third operational amplifier U3A is respectively connected between two diodes of the first double diode D1 and between two diodes of the second double diode D2, and the output end of the third operational amplifier U3A is connected with the reverse input end of the third operational amplifier U3A.
Therefore, through the utility model provides a solid-state switch automatic gain switching circuit of potentiometer for cathodic protection measurement when switching voltage gear uses solid-state mode because removed electromagnetic mechanical parts, has improved equipment life greatly, improves switching speed, prevents to lose the data value during the switching and makes measuring result intermittent to obvious energy consumption in the electromagnetic switching mode has been reduced and electromagnetic interference is avoided producing.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a potentiometer for cathodic protection measurement with adaptive range of a solid-state switch according to an embodiment of the present invention;
fig. 2 is a schematic view of a hysteresis curve provided by the embodiment of the present invention;
fig. 3 is a circuit diagram of a gain switching circuit of an automatic gain switching module of a solid-state switch according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a clamping circuit of an automatic gain switching module of a solid-state switch according to an embodiment of the present invention;
fig. 5 is a circuit diagram of a reference level generation circuit of an automatic gain switching module of a solid-state switch according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The core of the utility model lies in: the range of the sampling point is confirmed through the sampling of the high-speed low-precision ADC in the self-adaptive regulation module of the time-schedule, the required gain is further confirmed, and after the gain is confirmed, the gain switching can be realized by using the automatic gain switching module of the fixed switch.
Fig. 1 shows the structural schematic diagram of the potentiometer for cathodic protection measurement of solid-state switch adaptive range provided by the embodiment of the present invention, referring to fig. 1, the potentiometer for cathodic protection measurement of solid-state switch adaptive range provided by the embodiment of the present invention includes:
the device comprises a solid-state switch automatic gain switching module and a range self-adaptive adjusting module; wherein:
the range self-adaptive adjusting module is used for collecting the voltage of a sampling point through the sampling end, confirming the range according to a preset range switching algorithm and sending an adjusting instruction to the solid-state switch automatic gain switching module;
the solid-state switch automatic gain switching module is used for receiving an adjusting instruction, carrying out gain switching and outputting a gear switching driving signal; wherein, solid state switch automatic gain switches the module and includes:
the analog switch, the first operational amplifier and the second operational amplifier;
the analog switch receives the regulating instruction, the output of the analog switch is amplified by the first operational amplifier, and then impedance conversion is carried out by the second operational amplifier to obtain a driving signal, and the driving signal is output.
Specifically, the utility model discloses whole flow of range self-adaptation regulating module can include: the digital system main control carries out the pre-measurement process by sampling a signal tap through a high-speed ADC, and comprises the following steps: obtaining a voltage range in advance; and then, the gear requirement of high-precision measurement is met through a process switching flow.
The utility model discloses a pre-measurement includes: the voltage to be measured is collected through the sampling end, and the range of the signal to be measured is predicted in advance before high-precision sampling, so that a gain gear is preset.
The utility model discloses a range switches includes: and carrying out range switching by a range switching algorithm.
The utility model discloses the range self-adaptation technique that well range self-adaptation adjusting module used is based on the pre-measurement function of sacrificing precision in order to improve speed. When the device is operating normally, the continuous measuring frequency is 10Hz for example, and this measuring frequency is completely sufficient for dc potential measurement.
As an optional implementation manner of the embodiment of the present invention, the utility model discloses range adaptation is based on the pre-measurement and configurable hysteresis comparison function.
Wherein the pre-measurement comprises: the device uses the rough measurement to determine the range of voltage values each time the preparation time before the measurement.
As an optional implementation manner of the embodiment of the utility model, it includes to predetermine the range switching algorithm: hysteresis curves. Wherein, the hysteresis curve of the utility model is configurable, of course, the hysteresis comparison function is an example, and this algorithm or other range switching algorithms are all considered in the protection scope of the utility model. The specific algorithm content of the hysteresis comparison function is as follows: the gain threshold changes with the switching direction, so that the range is less likely to be switched randomly at two ends of the fixed threshold, and switching noise is introduced.
As an optional implementation of the embodiment of the utility model provides an adaptive regulation module of range for switch according to hysteresis curve control solid state switch automatic gain switching module, make when the voltage risees, switch to the wide-range according to hysteresis curve's high threshold, when the voltage reduces, switch to the small scale according to hysteresis curve's low threshold. Specifically, confirming the range according to the preset range switching algorithm includes: when the voltage of the sampling point rises to be larger than a first preset voltage value Uh, determining that a large range is required; when the voltage of the sampling point is reduced to be less than a second preset voltage Ul, determining that a small range is needed; wherein the second preset voltage Ul is smaller than the first preset voltage Uh.
In particular, the voltage range is determined by the size of the measured values. When the appropriate voltage value is used, the hysteresis curve as shown in fig. 2 is used for switching. That is, when the voltage rises, the range is determined by the right curve, and Uh is switched to a large range at a higher voltage; when the voltage decreases, the range is determined by the left-hand curve, and at a lower voltage Ul, the range is switched to a smaller range.
When the specific implementation, the utility model discloses a range switching mode is realized by software to can carry out the prediction of voltage fluctuation with code control specific range switching algorithm, for example with the Kalman filtering method, confirm new range. By the method, frequent change of precision along with time caused by more range jitter can be avoided, and later-period data analysis is convenient and feasible.
The utility model discloses the range of well range self-adaptation regulating module has compatibly, and the compatible small-scale range of wide range has certain allowance to the switch point in the small-scale range. What need be in the system is the data that do not make mistakes in succession in the cloudy guarantor, consequently, the utility model discloses switch the wide-range in advance and guaranteed data integrality under the prerequisite of having lost certain precision.
The utility model discloses a gain switching circuit of solid state switch automatic gain switching module explains with two grades of gains switching as an example, and more grades of gains can be obtained from this circuit extension, refer to fig. 3, the embodiment of the utility model provides a solid state switch automatic gain switching module includes: an analog switch U7, a first operational amplifier U5A, and a second operational amplifier U5B.
The input is the ANALOG _ IN port, and is amplified with controllable gain through the first operational amplifier U5A and the ANALOG switch U7, wherein the gain is controlled by the digital level (adjustment command) of the GC _ S1 port, which is x1 and x10 gains, respectively. After the gain amplification, the follower second operational amplifier U5B performs impedance conversion to obtain a larger driving capability, so that the amplified level signal (driving signal) is output from the ADC _ IN port to drive the high-precision ADC for the next analog-to-digital conversion process.
Specifically, the embodiment of the utility model provides a solid-state switch automatic gain switching circuit of potentiometer for cathodic protection measurement, include: the circuit comprises an analog switch U7, a first operational amplifier U5A, a second operational amplifier U5B, a first low-temperature drift precision resistor R4 and a second low-temperature drift precision resistor R9; a fifth terminal DA and a sixth terminal DB of the analog switch U7 are respectively connected to an inverting input terminal of the first operational amplifier U5A, a control terminal GC _ S1 of the analog switch U7 receives an adjustment instruction, a forward input terminal of the first operational amplifier U5A is a circuit input terminal, an output terminal of the first operational amplifier U5A is connected to one terminal of the first low-temperature-drift precision resistor R4 and a forward input terminal of the second operational amplifier U5B, the other terminal of the first low-temperature-drift precision resistor R4 is connected to the first terminal S3A and the second terminal S3B of the analog switch and one terminal of the second low-temperature-drift precision resistor R9, the other terminal of the second low-temperature-drift precision resistor R9 is connected to the third terminal S4A and the fourth terminal S4B of the analog switch, and an output terminal of the second operational amplifier U5B outputs a driving signal. Wherein: the analog switch U7 is selectively switched to the amplification feedback loop of the first operational amplifier U5A, and flows into the negative input terminal of the U5A through the GC _ FB path, and the second operational amplifier U5B performs impedance transformation on the output of the first operational amplifier U5A, so that the front-stage voltage can drive the rear-stage ADC with very low output impedance.
As an optional implementation manner of the embodiment of the present invention, the solid-state switch automatic gain switching module further includes: and the clamping circuit is used for protecting the input end of the first operational amplifier. Specifically, the utility model discloses when carrying out the gain switching, need have the protection to the input, prevent the mistake and switch over the damage to the back stage.
Specifically, referring to fig. 4, the clamp circuit includes: the clamp circuit comprises a third operational amplifier U3A, a first double diode D1 and a second double diode D2, wherein the forward input end of the third operational amplifier U3A is respectively connected with the input end of the first double diode D1, the output end of the second double diode D2 and the input end of the first operational amplifier U5A, the reverse input end of the third operational amplifier U3A is respectively connected between two diodes of the first double diode D1 and between two diodes of the second double diode D2, and the output end of the third operational amplifier U3A is connected with the reverse input end of the third operational amplifier U3A. The protection circuit utilizes the characteristic of the very high impedance input end of the insulated gate of the FET input operational amplifier, does not introduce an influence on the high impedance input end, and reduces leakage current by clamping the follow signal of the input end AMP _ IN, which is input to the operational amplifier U3A via the FET, such as the AMP _ GUARD end IN fig. 4. In the unclamped state, there is no voltage difference across the diode, thereby protecting the voltage state of the input terminal of the very high input impedance.
The AMP _ IN of the clamping circuit is correspondingly connected with the ANALOG _ IN input end. The AMP _ IN signal impedance-converted by the third operational amplifier U3A is used, and has a strong driving capability. The AMP _ IN signal after impedance conversion by the third operational amplifier U3A and the PE common terminal are clamped by a diode, because the voltages are identical, the AMP _ IN potential is equal to the AMP _ GUARD, and the high impedance input terminal AMP _ IN is not affected by the leakage current of the clamping diode, thereby reducing the input impedance. If the voltage exceeds the clamping range, the AMP _ GUARD is influenced firstly, and then the AMP _ IN is clamped and controlled, so that the influence of the clamping circuit on the high-resistance input end is reduced as much as possible, and the measurement accuracy is ensured to the greatest extent.
As an optional implementation manner provided by the embodiment of the present invention, the solid-state switch automatic gain switching module further includes: and a reference level generation circuit for generating a center reference level, the center reference level being used as a virtual ground.
In particular, since the clamp circuit requires a 0VDC reference level, this reference level is also used for biasing of the voltage measurement. Therefore, the generation of the 0VDC reference value is generated using the reference level generating circuit, as shown in fig. 5.
The reference level generating circuit includes: the fourth operational amplifier U3B performs impedance transformation on the 5V divided voltage through the fourth operational amplifier U3B to obtain a four-quadrant 2.5V voltage source that can be source-in and source-out.
Wherein, the PE end of the virtual ground, i.e. 2.5V, is made by using the fourth operational amplifier U3B to follow the resistance division value, which corresponds to 0V of the external measurement system. The advantage of doing so is that the use of dual power operational amplifiers is virtually avoided, the power consumption of the device can be reduced, and the complexity of the circuit is reduced.
Therefore, through the embodiment of the utility model provides a solid-state switch automatic gain switches module can realize that solid-state switches the gear, has avoided the use of relay or other mechanical element in accurate potentiometer. The technology has the advantages of silence, rapidness, low power consumption, long service life and the like, and when the chip supply is complete, the cost is far lower than that of a mechanical element switching scheme.
Therefore, utilize the embodiment of the utility model provides a solid-state switch is potentiometer for cathodic protection measurement of adaptive range can solve following problem:
in the cathodic protection measurement, the problem of low voltage measurement accuracy reduction caused by a fixed wide range is solved;
when the range is adjusted manually, the range is difficult to determine, and a part of over-range data measured easily for a long time is invalid;
the method of mechanically switching the range is difficult to dynamically switch the range and has high energy consumption;
when the range is dynamically switched, the measurement data is unreliable due to frequent range switching.
Utilize the embodiment of the utility model provides a solid state switch self-adaptation measuring range's for cathodic protection potentiometer has following technological effect:
when measuring potentials, long-time measurements experience large voltage fluctuations. And the automatic switching of the measuring range can realize wide-range high-precision measurement. For example, when the measurement is started, the voltage fluctuation is between 0 and 5V, and the 10V gear can realize the measurement with higher precision. In the other phase of measurement, the voltage fluctuation is between 0 and 50V, and the description of the whole voltage change process can be realized only by using a 100V gear.
When the voltage gears are switched, the solid-state mode is used, because electromagnetic mechanical parts are removed, the service life of equipment is greatly prolonged, the switching speed is improved, the phenomenon that data values are lost during switching to enable measuring results to be intermittent is prevented, obvious energy consumption in the electromagnetic switching mode is reduced, and electromagnetic interference is avoided.
The low leakage current clamping technique is an auxiliary function of the solid-state gain switching. Since the solid-state switching circuit is sensitive to voltage range variation, electronic elements such as an amplifier are easily burned out by an overvoltage compared with a mechanical method, and therefore, a clamp is required for protection. The classical diode clamping mode has the diode in a bias state for a long time, and the leakage current has great influence on the input end with high impedance, so that the novel amplifier is used for generating a follow-up voltage protection input end to realize no bias voltage from the input end to the protection end, thereby removing the leakage current and realizing the high impedance measurement without shunt.
The pre-measurement technology judges the range of the voltage through low-precision measurement, can help an algorithm to carry out next judgment, and ensures that the range of the measurement is correct. The hysteresis mode is used for switching the range, or a user-defined algorithm is used for switching the range, a specific range selection mode is used, certain hysteresis is introduced, or a Kalman filtering algorithm is used for prediction, so that frequent range jitter is avoided. The range switching can be reduced as much as possible within a certain range, so that the data is more reliable.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art to which the present application pertains. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (2)
1. A solid state switching automatic gain switching circuit for a potentiometer for cathodic protection measurement, comprising:
the circuit comprises an analog switch (U7), a first operational amplifier (U5A), a second operational amplifier (U5B), a first low-temperature drift precision resistor (R4) and a second low-temperature drift precision resistor (R9);
a fifth terminal (DA) and a sixth terminal (DB) of the analog switch (U7) are respectively connected to an inverting input terminal of the first operational amplifier (U5A), a control terminal (GC _ S1) of the analog switch (U7) receives an adjustment instruction, a forward input terminal of the first operational amplifier (U5A) is a circuit input terminal, an output terminal of the first operational amplifier (U5A) is connected to one end of the first low temperature drift precision resistor (R4) and a forward input terminal of the second operational amplifier (U5B), the other end of the first low temperature drift precision resistor (R4) is connected to a first terminal (S3A) and a second terminal (S3B) of the analog switch and one end of the second low temperature drift precision resistor (R9), the other end of the second low temperature drift precision resistor (R9) is connected to a third terminal (S4A) and a fourth terminal (S4) of the analog switch (4B), and an output driving signal output terminal 5B of the second operational amplifier (U B).
2. The circuit of claim 1, further comprising:
a clamping circuit comprising a third operational amplifier (U3A), a first dual diode (D1) and a second dual diode (D2), the forward input of the third operational amplifier (U3A) being connected to the input of the first dual diode (D1) and the output of the second dual diode (D2) and the input of the first operational amplifier (U5A), respectively, the reverse input of the third operational amplifier (U3A) being connected between the two diodes of the first dual diode (D1) and the two diodes of the second dual diode (D2), respectively, and the output of the third operational amplifier (U3A) being connected to the reverse input of the third operational amplifier (U3A).
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| CN202123267680.8U CN216851928U (en) | 2021-12-23 | 2021-12-23 | Solid-state switch automatic gain switching circuit of potentiometer for cathode protection measurement |
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| CN202123267680.8U CN216851928U (en) | 2021-12-23 | 2021-12-23 | Solid-state switch automatic gain switching circuit of potentiometer for cathode protection measurement |
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