CN109407020B - Magnetic axis measurement system of solenoid coil based on suspension wire method - Google Patents
Magnetic axis measurement system of solenoid coil based on suspension wire method Download PDFInfo
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
- G01R33/1261—Measuring magnetic properties of articles or specimens of solids or fluids using levitation techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
- G01R33/0029—Treating the measured signals, e.g. removing offset or noise
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
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Abstract
The application discloses a magnetic axis measurement system of a solenoid coil based on a suspension wire method, which comprises the following components: the metal suspension wire penetrates through the solenoid coil to be tested, and two ends of the metal suspension wire are connected with the traction weight after bypassing the positioning pulley; the metal suspension wires respectively penetrate through the middle parts of the two horizontal photoelectric detectors and the middle parts of the two vertical photoelectric detectors which are mutually and vertically arranged; the metal suspension wires respectively penetrate through the middle parts of two Helmholtz coils which are mutually and perpendicularly arranged; wherein, the light emitting heads of the photoelectric detectors are all connected with a driving circuit, and the receiving heads of the photoelectric detectors are all connected with a signal detection circuit; the metal suspension wire and the solenoid coil to be tested are respectively connected with a driving power supply; wherein, the drive circuit of the light emitting head of the photoelectric detector adopts constant current drive. The capability of the measuring system to resist the influence of external interference signals is improved.
Description
Technical Field
The application relates to the field of magnetic axis measurement of solenoid coils, in particular to a magnetic axis measurement system of a solenoid coil based on a suspension wire method.
Background
Magnetic axis measurement of solenoid coils by the wire suspension method is a very common magnetic axis measurement method at present, wherein a critical measurement part is non-contact measurement of the vibration position of fine wires. The suspension wire is a metal wire with the diameter of about 0.1mm and is horizontally placed, passes through the middle of the solenoid coil, and the two ends of the suspension wire are pulled by a weight to be straightened, and are static when the measurement is not performed. When a measurement is required, power is applied to the solenoid coil, and the solenoid coil is also energized, so that an axial magnetic field is generated in the middle of the solenoid. If the suspension wire is not positioned on the magnetic axis, the suspension wire is inevitably vibrated by a certain transverse force due to the action of a transverse magnetic field component, and the amplitude variation and the shape of the vibration are related to the size of the magnetic axis (namely, the magnetic axis offset and the inclination angle). If the vibration of the suspension wire can be measured, the magnitude of the magnetic axis can be calculated.
In a magnetic axis measurement system based on the suspension wire method, vibration of the suspension wire is detected by using a photoelectric switch type detector. The detector consists of a pair of small light emitting heads and light receiving heads which are oppositely arranged, the light emitting heads emit light rays, the light receiving heads receive the light rays and generate corresponding photocurrents in the light rays, and the magnitude of the photocurrents is related to the quantity of the received light rays; and the suspension wire is arranged between the light emitting head and the receiving head, and the suspension wire can block light rays emitted by the light emitting head from entering the receiving head. When the suspension wire vibrates, the part of the blocked light rays changes, so that the light rays obtained by the receiving head also change, and a changed photocurrent is generated in the light rays, which corresponds to the vibration amplitude of the suspension wire; thus, a change in photocurrent is detected, and thus a vibration of the suspension wire is detected. However, the detector's operating current is typically on the order of a few milliamperes, while the photocurrent, which can vary, is on the order of a few microamperes; in the current suspension vibration measurement, a resistor is used to convert the working current and the signal current of the detector into voltage signals, and a high-multiple (50-100 times) DC-AC-blocking amplifier is needed to amplify the slightly-changed voltage signals to obtain measurement data due to the high DC signal level. In the measuring process, an alternating current blocking amplifier is adopted for obtaining tiny signal change, so that the measuring system cannot obtain direct current working information of the detector, and cannot actually obtain position information of a suspension wire in a static state; in general, a suspension wire is required to be positioned at the middle position of a detector to obtain a better measurement signal, in order to adjust the suspension wire position to the middle position of the detector, a very expensive laser tracker is often used for achieving the adjustment, and because of the limitation of alignment precision, the problem that the alignment cannot be performed very accurately still exists, so that the vibration detection of the suspension wire can be influenced to a certain extent. On the other hand, since the frequency of the pulse driving current applied to the suspension wire is low, generally about 20Hz, the capacity of the dc blocking capacitor used is large, up to about 1000 μf or more, in order to obtain a low frequency signal during vibration as much as possible, which may cause a problem for signal coupling. In such a measurement system, the obtained magnetic axis measurement signal and the inclination measurement signal always have a certain coupling phenomenon, are not well separable, have adverse effects on the final magnetic axis parameters, and cannot further improve the accuracy of magnetic axis measurement. The position measurement system based on simple signal amplification is generally adopted, no matter what measurement line is adopted, but the principle is never separated, so that certain inconvenience and inaccuracy exist in the installation and debugging of the measurement system, and the offset and inclination signals in the magnetic axis measurement signals are always coupled together due to the insufficient performance; meanwhile, the effective measurement signal of the magnetic axis is a signal with smaller amplitude which is overlapped on the vibration signal with large amplitude, and the circuit adopting the measurement principle cannot obtain the effective measurement signal with sufficient amplitude, namely the effective measurement signal has smaller amplitude, so that certain difficulty is brought to the subsequent measurement signal processing, and the measurement accuracy is seriously influenced.
Disclosure of Invention
The application provides a magnetic axis measuring system of a solenoid coil based on a suspension wire method, which improves the capability of the measuring system for resisting the influence of external interference signals.
To achieve the above object, the present application provides a magnetic axis measuring system of a solenoid coil based on a suspension wire method, the system comprising:
the metal suspension wire penetrates through the solenoid coil to be tested, and two ends of the metal suspension wire are connected with the traction weight after bypassing the positioning pulley; the metal suspension wires respectively penetrate through the middle parts of the two horizontal photoelectric detectors and the middle parts of the two vertical photoelectric detectors which are mutually and vertically arranged; the metal suspension wires respectively penetrate through the middle parts of two Helmholtz coils which are mutually and perpendicularly arranged; wherein, the light emitting heads of the photoelectric detectors are all connected with a driving circuit, and the receiving heads of the photoelectric detectors are all connected with a signal detection circuit; the metal suspension wire and the solenoid coil to be tested are respectively connected with a driving power supply; wherein, the drive circuit of the light emitting head of the photoelectric detector adopts constant current drive.
Preferably, a driving circuit of the light emitting head of the photoelectric detector adopts constant current driving, and specifically comprises: the voltage regulator voltage input end is connected with a current source, the voltage regulator voltage output end is connected with the positive electrode of a first resistor, the negative electrode of the first resistor is connected with the luminous head of the photoelectric detector, and the voltage regulator voltage regulating end is connected with the negative electrode of the first resistor.
Preferably, the signal detection circuit includes: the first operational amplifier, the first current absorption branch, the sampling resistor and the filter; the receiving head of the photoelectric detector is connected with the negative input end of the first operational amplifier, and the negative input end of the first operational amplifier is a node for signal confluence; the positive input end of the first operational amplifier is grounded, the output end of the first operational amplifier is connected with the filter, and the output end of the filter is the output end of the signal detection circuit; two ends of the sampling resistor are respectively connected with a node of signal confluence and the output end of the first operational amplifier; the first current absorbing branch is connected with a node of signal confluence.
Preferably, each photoelectric detector in the system is correspondingly provided with a compensation photoelectric detector, the working environment of the compensation photoelectric detector is the same as that of the corresponding photoelectric detector, and the receiving head of the compensation photoelectric detector is connected with the signal converging node of the corresponding photoelectric detector signal detection circuit.
Preferably, the system further comprises a data collector, and the data collector is connected with the output end of the signal detection circuit.
Preferably, the data collector includes: a differential operational amplifier, an AD converter, a DA converter; the positive input end of the differential operational amplifier is connected with the output end of the signal detection circuit, the output end of the differential operational amplifier is connected with the output end of the AD converter, the output end of the AD converter is connected with the memory of the data acquisition unit, the memory of the data acquisition unit is connected with the input end of the DA converter, and the output end of the DA converter is connected with the negative input end of the differential operational amplifier.
Preferably, the system positions the wire in the middle of the photodetector by adjusting the position of the photodetector.
Preferably, the photodetector comprises a light emitting head and a receiving head, the metal suspension wire being located intermediate the light emitting head and the receiving head.
Preferably, the system is such that the wire is in tension during measurement.
Preferably, the coil is a helmholtz coil.
The magnetic axis measurement signal processing system of the solenoid coil comprises constant current and constant voltage driving of a photoelectric detector, a key circuit capable of finishing offset current offset of a working point under higher signal level offset, a compensation circuit capable of eliminating drift performance of the detector, a suspension wire static position indication reading device and the like.
The technical scheme adopted for solving the technical problems is as follows: in a magnetic axis measuring system of a solenoid coil, vibration of a suspension wire is measured using a photoelectric detector of a photoelectric switch type. Firstly, a constant current driving circuit is adopted to supply power to a light emitting head of a photoelectric detector so as to ensure constant light emission and reduce the influence of fluctuation of the power supply circuit on a measurement signal. Secondly, aiming at the driving problem of the receiving head, the power is supplied in a constant-voltage working voltage mode to reduce the influence of the change of the working point voltage on the measurement of the micro signal; on one hand, a constant voltage power supply is adopted for supplying power, but the working voltage of the receiving head is not represented as constant voltage, and the other end of the receiving head is required to be processed; the virtual ground concept of the input end of the operational amplifier is utilized, the purpose of grounding the detector receiving head in a virtual ground mode is achieved by connecting the output end of the receiving head to the negative input end of the operational amplifier and grounding the positive input end of the amplifier, and therefore real constant voltage driving is achieved on the receiving head, and the influence of voltage variation on signal current is reduced. In this form of signal measurement, the current signal is directly detected and no longer the voltage signal. However, the detector quiescent operating current is on the order of a few milliamperes, while the effective signal current is on the order of a few microamps, differing by a factor of about 1000, and signal processing can present an insurmountable problem if only a simple amplification circuit is employed. Therefore, the detector quiescent operating current needs to be cancelled, and only the signal current generated by the detector needs to be extracted for signal processing. Because the negative input end of the operational amplifier is of a virtual ground structure, the negative input end is used as a current converging node, various currents flow in and out of the current converging node, and the working parameters of the circuit are not affected; a current absorption branch can be added on the detector to absorb the static working current of the detector to other places; when the sink current is equal to the quiescent operating current, the current on this node is zero even though there are other branches on this node. If the detector generates a change of signal current (such as suspension wire vibration) under illumination to cause a change of working current, the current entering and exiting at the node will change, and if other current entering and exiting branches exist, the changed current enters and exiting from the branches, so that only an electric signal related to the signal change is generated on the branches, the serious influence of higher direct current (static working current) is avoided, and the effects of extracting and independently processing the micro signal current are played. The microampere-level current can be converted into a volt-level voltage signal through a resistor with a larger resistance value (such as 100 kiloohms), so that the subsequent signal processing system can be conveniently processed, and even the subsequent signal processing system can be directly used for digital-to-analog conversion without amplification to obtain a signal value for calculation processing; the resistance value of the conversion resistor is changed, and the circuit parameters of other processing parts are not changed, so that the method is very suitable for signal processing with different bandwidths. In such a signal measurement system, since the detected actual position signal (possibly having a certain deviation, but forming a corresponding relation |) of the suspension wire relative to the detector, it can obtain a measurement signal of the static position of the suspension wire for judging the position of the suspension wire, and at the same time, plays a role in adjusting the static position of the suspension wire, avoiding using other expensive and high-precision instruments to measure the position of the suspension wire, and can greatly improve the debugging efficiency. The further current cancellation line principle can also add a compensating line part of detector drift (time drift and temperature drift): at the current confluence node, a measurement branch which is in the same environment as the detector is added, but no suspension wire passes through the middle position of the measurement branch, and the working current is in an outflow state so as to offset the static working current of the actual measurement branch of the suspension wire; because the static working current of the detector may have a certain difference and cannot be completely counteracted, a constant current source branch with an adjustable direction can be additionally arranged at the node to counteract the current which cannot be completely counteracted. The detection structure has the compensation and offset effects of certain drift performance, so that the influence capacity of inhibiting drift on measurement can be improved, and the measurement accuracy can be improved to a certain extent.
The application adopts a signal processing circuit principle capable of eliminating high bias level, can simply transform tiny signal current generated when the suspension wire vibrates, does not need to use an amplifier with high amplification factor to amplify a measurement signal, and eliminates the key problem that the change of an original circuit working point and the change of signal current are coupled together to influence the measurement signal; meanwhile, in order to improve the capability of the measuring system for resisting the influence of external interference signals, a high-precision constant-current driving mode is adopted to drive the detector, on the other hand, in order to reduce the influence of the change of the working point of the detector on the output signal current, a virtual ground access mode is adopted to drive and extract signals from the output end of the detector, a relatively pure suspension vibration position signal is obtained for the magnetic axis signal processing of the solenoid coil under the condition of ensuring the unchanged working point of the detector, the influence of low-frequency baseline inclination and fluctuation in the original measuring signal is eliminated to a great extent, the offset and inclination signals in the magnetic axis measuring signal are separated more easily, the resolving power of the measuring signal is improved, and further the measuring precision is greatly improved. The adopted measuring mode can obtain the signal corresponding to the suspension wire static position, so that the difficulty in adjusting the suspension wire static position is solved, the difficulty and the cost for accurately adjusting the suspension wire static position are greatly reduced, and the debugging efficiency of the measuring device is also greatly improved.
The one or more technical schemes provided by the application have at least the following technical effects or advantages:
the detector is driven by constant current on one hand so as to obtain a more stable working state; on the other hand, the principle of a signal processing circuit capable of eliminating high bias level is adopted, tiny signal current generated during suspension wire vibration can be simply converted and voltage signals with enough amplitude can be obtained, an amplifier with high amplification factor is not needed to amplify measurement signals, the key problem that the change of an original circuit working point and the change of signal current are coupled together to influence the measurement signals is eliminated, the influence of low-frequency baseline inclination and fluctuation in the original measurement signals is eliminated to a great extent, offset and inclination signals in a magnetic axis measurement signal are more easily separated, the resolution capability of the measurement signals is improved, and further the measurement accuracy is greatly improved. The adopted measuring mode can obtain the signal corresponding to the suspension wire static position, so that the difficulty in adjusting the suspension wire static position is solved, the difficulty and the cost for accurately adjusting the suspension wire static position are greatly reduced, and the debugging efficiency of the measuring device is also greatly improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application;
FIG. 1 is a schematic diagram of a structure and layout of a solenoid coil magnetic axis measurement system based on a suspension wire method;
FIG. 2 is a schematic diagram of the construction of a photo-detector of the photo-switch type;
FIG. 3 is a schematic diagram of constant current drive of a photodetector light emitting head;
FIG. 4 is a schematic diagram of a conventional signal detection circuit;
FIG. 5 is a schematic diagram of a signal processing circuit with high bias level cancellation;
FIG. 6 is a schematic circuit diagram for suppressing the effects of drift;
FIG. 7 is an illustration of the change in the suspension wire static position adjustment signal;
FIG. 8 is a schematic illustration of a route for data acquisition;
FIGS. 9a-b are graphs comparing measured signals of magnetic axis offset;
FIGS. 10a-b are graphs comparing measured signals of magnetic axis tilt;
in the figure, a 1-metal suspension wire, a 2-positioning pulley, a 3-traction weight, a 4-X direction photoelectric detector, a 5-Y direction photoelectric detector, a 6-solenoid coil, a 7-Helmholtz coil, an 8-photoelectric detector driving circuit, a 9-photoelectric detector signal detection circuit, a 10-photoelectric detector luminous head, an 11-photoelectric detector receiving head, a 12-adjustable constant current source, a 13-operational amplifier, a 14-sampling resistor, a 15-compensation photoelectric detector, a 16-differential operational amplifier, a 17-AD converter, an 18-data acquisition device and a 19-DA converter.
Detailed Description
The application relates to a magnetic axis measuring system of a solenoid coil based on a suspension wire method, which reduces the influence of signal change on a working point by arranging a current source circuit capable of directly eliminating higher bias working point voltage so as to extract tiny change signals superposed on a signal with larger amplitude, and then processes offset and inclination signals of a magnetic axis.
In order that the above-recited objects, features and advantages of the present application will be more clearly understood, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description. In addition, the embodiments of the present application and the features in the embodiments may be combined with each other without collision.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than within the scope of the description, and the scope of the application is therefore not limited to the specific embodiments disclosed below.
Solenoid coil magnetic axis measurement system:
fig. 1 is a basic configuration of a magnetic axis measuring system of a solenoid coil based on a suspension wire method, and mainly comprises two groups of X-direction photodetectors 4, Y-direction photodetectors 5, a photodetector driving circuit 8, a photodetector signal detecting circuit 9, two groups of coils such as helmholtz coils 7 and driving constant current sources I3 which are arranged in a mutually perpendicular manner, a metal suspension wire 1 with a diameter of about 0.1mm and a driving power source I2 which are positioned by a positioning pulley 2 and pulled and tightened by a traction weight 3, a measured solenoid coil 6 and a driving constant current source I1 which are driven by the same, and the like, and further comprises a data acquisition related part.
The metal suspension wire 1 is tensioned and placed in a horizontal position at both ends using a suspended traction weight 3 and ensures that the metal suspension wire 1 is placed in a middle position of the two sets of photodetectors 4, 5 (achieved by adjusting the detector mounting brackets etc.) and in a central axis position of the solenoid coil 6. The metal suspension wire 1 is loaded with low-frequency pulse current, the measured solenoid coil 6 is also loaded with constant current, a magnetic field is generated inside the solenoid, and meanwhile, the Helmholtz coil 7 is also loaded with certain current to modulate the vibration of the metal suspension wire 1; when the solenoid magnetic axis is deviated, that is, a certain included angle is formed between the solenoid magnetic axis and the metal suspension wire 1, the metal suspension wire 1 loaded with current is subjected to a transverse lorentz force by the transverse component (approximately perpendicular to the wire) of the magnetic field generated by the solenoid coil 6 to generate a mechanical vibration with a superimposed modulation effect, the modulation amplitude of the metal suspension wire 1 is in direct proportion to the integral value of the transverse magnetic field component along the axial direction and the width and the amplitude of the current pulse on the metal suspension wire 1, the amplitude waveform of the metal suspension wire 1 is measured to obtain the modulation amplitude on the metal suspension wire, and parameters such as the suspension wire driving current, the solenoid coil working current and the like can be calculated to obtain the magnetic axis information of the solenoid coil, including the offset and the inclination angle.
Constant current driving of the photodetector:
the light emitting heads 10 of the photodetectors 4, 5 are driven with constant current to improve the stability of light emission and reduce the influence of light emission fluctuation. One specific circuit form is shown in fig. 3, in which a three terminal adjustable voltage regulator LM317 is used, and if the resistor is 60 ohms, a constant current of about 20mA is generated, which can be used to drive the light emitting head of the photodetector.
Conventional methods of photodetector signal detection principle:
a conventional method in a micro signal detection technology with a higher bias level is to use an ac dc-blocking amplifier to extract and amplify a small signal superimposed on a large signal, as shown in fig. 4, which is also a line principle that has been adopted in a solenoid coil magnetic axis measurement technology, and the basic principle has not been changed in any way.
The static operating current of the photodetector is at a level of several mA, and when the suspension wire vibrates, the generated current changes at a level of about several μa. As shown in fig. 4, the normal signal detection circuit is shown in fig. 4, the dc bias voltage at the measurement point is generally at a level of several volts, and the variation amplitude of the effective signal is only about several mV, so that an ac dc blocking amplifier (or a band-pass filter BPF) is generally adopted to amplify the signal, the coupling capacitor Co with a large capacity is used to isolate the dc signal and pass the ac signal, and the amplification factor needs to reach a higher level to obtain the effective signal with obvious difference, which is generally about 50 times or more; because the frequency of the driving pulse is about 20Hz, the capacity of the coupling capacitor Co is required to be larger so as to have better coupling effect on the low-frequency signals, but the problem of inclination of the low-frequency baseline signals is easy to generate, so that the magnetic axis inclination and the offset signals are coupled together, and the separation processing of the signals is not facilitated. The improvement work is only carried out on the performance of the filter, and a cut-off frequency exists at the low-frequency end all the time and a direct-current bias signal cannot be obtained no matter how a subsequent filter circuit is designed; because the circuit is based on the amplification processing of small signal change, the output signal only reflects the dynamic change of the amplitude in the vibration process of the suspension wire, the actual position signal of the suspension wire cannot be obtained at the output end, the position of the suspension wire relative to the detector cannot be known exactly, and the adjustment of the initial static position of the suspension wire is not facilitated, so that the good vibration signal is obtained.
Improvement of photodetector signal detection:
in order to obtain the actual position signal and the static position adjustment capability of the vibration of the metal suspension wire 1, the conventional detection circuit principle is improved, and a processing principle similar to differential bias elimination is adopted as shown in fig. 5.
The virtual ground concept of the input end of the operational amplifier 13 is utilized to provide the stable operating power supply Vref (+ 10V) for the light receiving end 11 of the detector, so that the influence of the output signal change on the operating point is eliminated. Selecting an operational amplifier 13 with smaller negative input bias current and drift to reduce the influence on the measured current Is; the negative input of the operational amplifier 13 Is used as a node of signal confluence, and a current absorbing branch 12 (Ic) Is additionally provided, wherein the current on the current absorbing branch can counteract the larger static working current Is of the detector, so that only a tiny signal current delta i generated when the suspension wire vibrates can flow through the sampling resistor 14 (Ro) and generate a larger voltage signal Vo '(Vo' =delta i-Ro, which Is determined by the resistance value of Ro) at the output end. The subsequent processing of the signals is simpler, only low-pass filtering processing or amplification with low amplification factor is needed, a chebyshev low-pass filter LPF based on multipoint feedback is adopted in a specific measuring line, the passband is 2kHz, the in-band fluctuation is 0.3dB, the cut-off frequency is 6kHz, and the out-of-band attenuation is not less than 50dB. In such a measurement line, the amplitude of the output signal is related to two factors: the initial position of the suspension wire and the resistance value of the resistor Ro. The initial position of the suspension wire directly influences the variable amplitude of the vibration signal, and influences the effective change range of the signal; ro directly affects the amplitude of the converted voltage output signal, and the change of the Ro resistance value does not affect the subsequent filter parameters, so that the on-site debugging is facilitated. Because the output signal is directly related to the output current (including the change part) of the detector, the static current signal part is eliminated, and the actual position information of the suspension wire is still contained, the system can obtain the static initial position of the suspension wire, and the initial position adjustment of the suspension wire is facilitated without the aid of other high-precision measuring instruments, so that the measuring efficiency is improved.
Compensation of photodetector signal detection:
with respect to the influence of the change of the ambient light condition, the temperature drift, the time drift and the like on the photoelectric detector, a certain improvement can be made on the application structure of the detector, as shown in fig. 6. Assuming that the photodetector 11 (T1) is used for suspension vibration measurement and the photodetector 11 (T2) is used for compensation, then T2 is only required to be in the same working environment as T1; at this time, the quiescent currents Is1 and Is1 of T1 and T2 should cancel each other out, including the drift performance, and this form can also cancel the problems caused by the detector drift including the ambient light change to some extent. However, there may be a factor of variability in device performance, and the current may not be completely cancelled, and at this time, a constant current source 12 (Ic) with adjustable current and direction may be added to cancel out the current in this portion, so that the capability of processing the pure minute signal may be obtained.
The capacity has a great effect on solving the problem of slow drift of the measurement signal, thereby improving the quality of reference signal acquisition and being beneficial to further processing of the signal.
And (3) adjusting the static position of the suspension wire:
the suspension wire is in the middle position of the detector by adjusting the position of the photoelectric detector. Adjusting the mounting bracket of the detector to enable the suspension wire to transversely pass through the middle position of the detector back and forth, and realizing a process of changing the position indication reading, so as to generally know the maximum condition of the position indication reading; the support is adjusted so that the position reading is at or near the maximum reading, at which point the position of the suspension wire is substantially in the middle of the detector. This process is shown in fig. 7. The adjusting mode utilizes the function of the suspension wire vibration measuring system, avoids the use of expensive precise instruments, greatly simplifies the adjusting difficulty of the suspension wire position and greatly improves the efficiency of the suspension wire position adjustment.
And a data acquisition system:
when the reference signal is collected, a constant bias value such as zero is output to the outside by the data collector 18 with the D/a conversion function 19, and is input to the negative input terminal of a differential operational amplifier 16, the positive input terminal of the differential operational amplifier 16 inputs the suspension vibration signal processed previously, and at this time, the reference signal is actually obtained at the input terminal of the data collector 18, and data conversion is performed, and stored in the memory of the data collector 18. When the modulated vibration signal of the suspension wire is to be acquired, the previously acquired reference signal needs to be synchronously converted into an analog signal at the D/a output terminal 19 of the data acquisition device 18, and the analog signal is subjected to differential operation with the suspension wire vibration signal at the differential amplifier 16 to obtain a pure modulated vibration signal for a/D conversion of the data acquisition device 18, and the obtained signal is the required signal which can be used for calculating the magnetic axis parameter. This process is shown in fig. 8.
Effect of photodetector signal detection:
under the same measuring conditions and environments, the original measuring circuit and the measuring system of the application are adopted to carry out contrast measurement on the vibration of the suspension wire. The obtained magnetic axis tilt measurement waveforms are shown in fig. 9 a-b; obviously, at different signal levels, the effective signals obtained by the measuring system are all quite flat rectangular waveforms or have relatively small inclination, and are consistent with theoretical simulation results, so that the signal processing system is beneficial to further processing of the signals. In the signals obtained by the original measuring system, a serious baseline inclination exists, and certain distortion exists, so that the data processing of the signals has certain difficulty. The obtained magnetic axis offset measurement waveforms are shown in fig. 10 a-b; an offset signal waveform superimposed on the tilt signal is included. Because the base line part is relatively straight (corresponding to the inclination signal), the offset signal (peak part) of the magnetic axis is easier to distinguish and extract, and the measurement precision can be improved; in the signals obtained by the original measuring system, large fluctuation and obvious inclination of the base line always exist, and when the offset signals become smaller, the offset signals are more likely to be unrecognized, so that the measuring precision cannot reach a higher level.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (6)
1. A solenoid coil magnetic axis measurement system based on a suspension wire method, the system comprising:
the metal suspension wire penetrates through the solenoid coil to be tested, and two ends of the metal suspension wire are connected with the traction weight after bypassing the positioning pulley; the metal suspension wires respectively penetrate through the middle parts of the two horizontal photoelectric detectors and the middle parts of the two vertical photoelectric detectors which are mutually and vertically arranged; the metal suspension wires respectively pass through the middle parts of two horizontal coils and the middle part of a vertical coil which are mutually and vertically arranged; wherein, the light emitting heads of the photoelectric detectors are all connected with a driving circuit, and the receiving heads of the photoelectric detectors are all connected with a signal detection circuit; the metal suspension wire and the solenoid coil to be tested are respectively connected with a driving power supply; wherein, the drive circuit of the light-emitting head of the photoelectric detector adopts constant current drive;
the drive circuit of the light emitting head of the photoelectric detector adopts constant current drive, and specifically comprises: the voltage regulator voltage input end is connected with a current source, the voltage regulator voltage output end is connected with the positive electrode of a first resistor, the negative electrode of the first resistor is connected with the light emitting head of the photoelectric detector, and the voltage regulator voltage regulating end is connected with the negative electrode of the first resistor;
wherein, the signal detection circuit includes: the first operational amplifier, the first current absorption branch, the sampling resistor and the filter; the receiving head of the photoelectric detector is connected with the negative input end of the first operational amplifier, and the negative input end of the first operational amplifier is a node for signal confluence; the positive input end of the first operational amplifier is grounded, the output end of the first operational amplifier is connected with the filter, and the output end of the filter is the output end of the signal detection circuit; two ends of the sampling resistor are respectively connected with a node of signal confluence and the output end of the first operational amplifier; the first current absorption branch is connected with a node of signal confluence;
each photoelectric detector in the system is correspondingly provided with a compensation photoelectric detector, the working environment of the compensation photoelectric detector is the same as that of the corresponding photoelectric detector, and the receiving head of the compensation photoelectric detector is connected with the signal converging node of the corresponding photoelectric detector signal detection circuit.
2. The system for measuring the magnetic axis of a spiral coil based on the suspension wire method according to claim 1, further comprising a data collector connected to the output end of the signal detection circuit.
3. The system for measuring the magnetic axis of a solenoid coil based on the suspension wire method according to claim 2, wherein the data collector comprises: a differential operational amplifier, an AD converter, a DA converter; the positive input end of the differential operational amplifier is connected with the output end of the signal detection circuit, the output end of the differential operational amplifier is connected with the output end of the AD converter, the output end of the AD converter is connected with the memory of the data acquisition unit, the memory of the data acquisition unit is connected with the input end of the DA converter, and the output end of the DA converter is connected with the negative input end of the differential operational amplifier.
4. The cantilever coil based magnetic axis measurement system of claim 1, wherein the system positions the metal cantilever wire in the middle of the photodetector by adjusting the position of the photodetector.
5. The cantilever-based solenoid coil magnetic axis measurement system of claim 1, wherein the photodetector comprises a light emitting head and a receiving head, the metal cantilever being positioned intermediate the light emitting head and the receiving head.
6. The cantilever coil based magnetic axis measurement system of claim 1, wherein the system is configured such that the metallic cantilever wire is in tension during measurement.
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