CN209784513U - Calibration control device and calibration device for magnetic moment measurement small coil turn area - Google Patents
Calibration control device and calibration device for magnetic moment measurement small coil turn area Download PDFInfo
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- CN209784513U CN209784513U CN201822233833.9U CN201822233833U CN209784513U CN 209784513 U CN209784513 U CN 209784513U CN 201822233833 U CN201822233833 U CN 201822233833U CN 209784513 U CN209784513 U CN 209784513U
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Abstract
A calibration control device and a calibration control device for a small coil turn area for measuring magnetic moment comprise: the device comprises a base mechanism, a motion adjusting mechanism and a supporting mechanism which are arranged from bottom to top, wherein a motor, a rotating shaft and a mercury slip ring are arranged above the supporting mechanism; two ends of the rotating shaft are respectively connected with the motor output shaft and the mercury slip ring; a coil fixing plate comprising a counter bore and a guide groove is arranged in the rotating shaft, and a coil is placed in the counter bore and led out through the guide groove and the mercury slip ring; the motor is fixed on the supporting mechanism through the motor bracket; the rotating shaft is fixed with the bearing support, and the bearing support penetrates through the supporting mechanism and is fixed on the movement adjusting mechanism. The calibration device comprises a calibration control device, a pair of permanent magnets, a nuclear magnetic resonance magnetometer, a voltmeter and a frequency meter; the N pole of one permanent magnet is opposite to the S pole of the other permanent magnet; the calibrated coil and the rotating shaft are arranged between the N pole and the S pole, and the nuclear magnetic resonance magnetometer is arranged on one side close to the N pole; the voltmeter and the frequency meter are respectively connected with the mercury slip ring.
Description
Technical Field
The utility model belongs to permanent magnetism moment measurement field, concretely relates to moment measurement is with calibration controlling means and calibrating device of little coil circle area.
background
Helmholtz in 1849, german scientist designed helmholtz coils. The helmholtz coil is generally formed by a pair of circular coils connected in series in the same direction to generate a uniform magnetic field with low intensity and a large range. Connecting the calibrated helmholtz coil to a calibrated flux integrator can be used for accurate measurement of magnetic moment.
Fig. 1 shows an open-circuit measuring device for a helmholtz coil. The whole set of devices is placed in a non-ferromagnetic environment, for example: placed on a wooden table. As shown, the magnet is placed in the center position (homogeneous region) of the coil during measurement, and the magnetization of the magnet is in the x-axis direction, i.e., parallel to the axial direction of the coil. The two coil signals connected in series are directly transmitted to the magnetic flowmeter. After adjusting the zero point of the fluxmeter, the magnet is moved out of the coil so that it is parallel to the coil axis. The distance removed is typically 75-100 cm, which allows the sample to have no effect on the reading. By integrating the voltage with time (magnetic flux), the open magnetic moment of the sample can be obtained. Another measurement method is to rotate the sample 180 degrees without taking the sample out, so that the generated voltage will be 2 times that of the original, and the coil constant will be 1/2 of the original.
FIG. 1 is a schematic diagram of a method for measuring the permanent magnetic moment of a magnetic flux integrator and a Helmholtz coil,
When a magnetized sample is pulled from a Helmholtz coil, the magnetic dipole moment of the sample can be determined by:
j＝Δφ/kh (1.1)
In the formula: j is the magnetic dipole moment, in Webber meters (Wb m); k is a radical ofhThe Helmholtz coil constant is obtained by taking the ratio of the magnetic field intensity to the current kh as H/I and the unit of A/m/A; delta phi is the flux variation when the sample rotates or is drawn out of the detection coil, and the unit is Weber (Wb); h is the magnetic field strength, and the unit is ampere per meter (A/m); i is the current intensity in amperes (A);
When the sample is rotated 180 ° at the center of the search coil, equation (1) evolves:
J＝ΔΦ/2kh (1.2)
The magnetic flux integrator measures the magnetic flux by measuring the induced voltage change generated during the rotation or drawing of the sample from the detection coil. The flux integrator may be calibrated using standard mutual inductance or volt-second generators.
The helmholtz coil needs to be calibrated before use. The Helmholtz coil should ensure that its homogeneous region covers the shape and volume of the sample to be measured. Coil constant (magnetic field strength to current strength ratio) k of Helmholtz coilhThis can be obtained by measuring the current through the coil and measuring the magnetic field strength in the centre of the coil with a magnetic field detecting device. Because the current intensity is easy to realize high-precision measurement, the technical difficulty of the conventional Helmholtz coil calibration method is mainly concentrated on the accurate measurement of the magnetic field intensity at the center of the coil. The helmholtz coil calibration method can be divided into a direct current method and an alternating current method. The direct current method is to apply constant direct current to the Helmholtz coil, measure the central magnetic field of the coil by using a direct current magnetic field measuring instrument, and calculate the coil constant from the measured values of the magnetic field and the current. Because the field generated by the Helmholtz coil is very small, the field is generally about (10-100) Gs under the allowable current, the geomagnetic field, the stray field and the zero point of the measuring instrument all bring great influence, and the uncertainty of the calibration is generally about 0.3%. More importantly, the flow type nuclear magnetic resonance magnetometer and the electron spin resonance magnetometer which are suitable for direct current calibration cannot be purchased in the market. Therefore, the alternating current method is now beginning to be used to calibrate the helmholtz coil.
The measurement by the alternating current method is to electrify a Helmholtz coil with constant sine wave current, and place a small coil with a known turn area in the Helmholtz coilThe coil constant is calculated by accurately measuring the induced voltage of the small coil, see formula (1.3). As can be seen from equation (1.3), khderived from the voltage, current, frequency and small coil turn area, wherein the current and frequency can be accurately determined. Therefore, the key factor of the ac calibration is the uncertainty of the small coil NS and whether the voltage effective value signal under the influence of the spatial stray field can be accurately measured.
Urms＝2πf·NS·μ0·kh·Irms (1.3)
wherein: u shapermsinducing voltage for the small coil; f is the signal source frequency; NS is the area of the turn of the small coil; mu.s0Is a magnetic constant; k is a radical ofhIs the helmholtz coil constant; i isrmsthe current flowing through the helmholtz coil.
The conventional means for calibrating the coil constants are two, one is to calibrate the coil in a solenoid by an impact method, and the other is to calibrate the coil by turning or pulling the coil in a uniform field.
A small constant coil (NS is less than or equal to 100cm2) precision measuring device. The measurement principle of the device is mainly based on the electromagnetic induction law:
NS is coil constant (m 2); Δ B is the amount of change (T) in the magnetic induction in the coil; e is the induced potential (V) in the coil;
If the induced potential e is converted by v/f, then:wherein K is a V/f conversion constant (V/Hz); c is the counting value obtained by sending the frequency signal output by the v/f converter into the counter.
Because the rotating coil mode is selected to change the magnetic field, a Hall effect stable field is adopted in the test, NMR is used for monitoring the magnetic field, and the formula (1.7) can be rewritten as follows:
according to fig. 1, the measuring coil is placed in the center of the magnetic field, the coil is rotated 180 degrees in the horizontal direction under the control of the rotation controller, the induced potential in the coil is photoelectrically amplified, the V/f conversion is sent to a counter for counting, and finally the measuring result is calculated according to the formula (1.8).
However, the method cannot leave the integrator, the uncertainty of the integrator is hardly better than 0.1% at present, so that the uncertainty of the turn area is about 0.2% under the best condition generally, the calibration capability of the electromagnetic station of a measuring yard is 0.16% -0.33%, and the calibration uncertainty cannot meet some technical index requirements.
SUMMERY OF THE UTILITY MODEL
Objects of the invention
The utility model aims at providing a calibration control device and calibrating device of little coil circle area (NS) are surveyed to rotation method based on high degree of consistency permanent magnetism standard field.
(II) technical scheme
in order to solve the above problem, a first aspect of the present invention provides a calibration control device for measuring magnetic moment with small coil turn area, including: the device comprises a base mechanism, a motion adjusting mechanism and a supporting mechanism which are sequentially arranged from bottom to top, wherein a motor, a rotating shaft and a mercury slip ring are arranged above the supporting mechanism; one end of the rotating shaft is connected with an output shaft of the motor, and the other end of the rotating shaft is connected with the mercury slip ring; a coil fixing plate is arranged in the rotating shaft and comprises a counter bore and a guide groove, and a coil is placed in the counter bore and led out through the guide groove and the mercury slip ring; the motor is fixed on the supporting mechanism through a motor bracket; the rotating shaft is fixed with the bearing support, and the bearing support penetrates through the supporting mechanism and is fixed on the movement adjusting mechanism.
According to the utility model discloses an another aspect provides a magnetic moment measurement is with calibrating device of little coil turn area, including calibration controlling means, still include: a pair of permanent magnets, a nuclear magnetic resonance magnetometer, a voltmeter and a frequency meter; the N pole of one permanent magnet is opposite to the S pole of the other permanent magnet; the calibrated small coil and the rotating shaft are positioned between the N pole and the S pole, and the nuclear magnetic resonance magnetometer is arranged on one side close to the N pole; the voltmeter and the frequency meter are respectively connected with the mercury slip ring.
(III) advantageous effects
the above technical scheme of the utility model has following profitable technological effect: the small coil NS is calibrated by adopting a method of continuously rotating the coil in a uniform field, the uniform field is a high-uniformity standard magnetic field made of a permanent magnet, the magnetic field intensity is about 3500Oe, a motor with high rotating speed stability is used for driving the coil to rotate in the uniform field at a fixed frequency, the stability of the rotating frequency is ensured, and the small coil NS can be accurately determined by measuring the induced voltage and the induced frequency by a voltmeter.
drawings
FIG. 1 is a schematic diagram of a prior art magnetic moment measurement principle of a permanent magnet of a magnetic flux integrator and a Helmholtz coil;
Fig. 2 is a schematic structural diagram of a calibration control device for measuring a magnetic moment with a small coil turn area according to an embodiment of the present invention;
Fig. 3 is a schematic external structural diagram of a calibration control device for measuring a magnetic moment with a small coil turn area according to an embodiment of the present invention;
Fig. 4 is a schematic structural diagram of a base mechanism in a calibration control device for measuring magnetic moment with a small coil turn area according to an embodiment of the present invention;
Fig. 5 is a schematic structural diagram of a rotating shaft and a motor of the calibration control device for measuring a magnetic moment with a small coil turn area according to the embodiment of the present invention, which are mounted on a supporting platform;
Fig. 6 is a schematic structural diagram of a moving plate in a calibration control device for measuring a magnetic moment with a small coil turn area according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a supporting mechanism in a calibration control device for measuring a magnetic moment with a small coil turn area according to an embodiment of the present invention;
Fig. 8 is a schematic structural diagram of a coil fixing plate in the calibration control device for measuring magnetic moment with small coil turn area according to the embodiment of the present invention;
fig. 9 is a schematic structural diagram of a calibration apparatus for measuring a magnetic moment with a small coil turn area according to an embodiment of the present invention;
fig. 10 is a diagram of the range of the permanent magnet standard field design uniformity region according to an embodiment of the present invention.
Reference numerals:
1: a base mechanism; 11: an aluminum alloy frame; 12: reinforcing ribs; 13: a work table; 14: a transition plate connecting plate; 2: a movement adjustment mechanism; 21: fixing a bracket; 22: a motion plate; 221: a positioning mechanism; 2211: positioning holes; 2212: positioning the edge; 222: a weight reduction groove; 23: a fixed base; 24: a precision manual angular position table; 3: a support mechanism; 31: a support platform; 32: supporting the upright post; 33: a permanent magnetic standard field cushion block; 4: a motor; 5: a rotating shaft; 51: a right rotating shaft; 52: a rotating shaft; 53: a left rotating shaft; 6: a mercury slip ring; 7: a coil fixing plate; 71: a counter bore; 72: a guide groove; 721: a first guide groove; 722: a second guide groove; 8: a motor bracket; 9: a bearing support; 10: a protective cover.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the description is intended to be illustrative only and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
As shown in fig. 2 and 3, a calibration control device for a small coil turn area for magnetic moment measurement includes: the device comprises a base mechanism 1, a motion adjusting mechanism 2 and a supporting mechanism 3 which are sequentially arranged from bottom to top, wherein a motor 4, a rotating shaft 5 and a mercury slip ring 6 are arranged above the supporting mechanism 3; one end of the rotating shaft 5 is connected with an output shaft of the motor 4, and the other end of the rotating shaft is connected with the mercury slip ring 6; a coil fixing plate 7 is arranged in the rotating shaft 5, the coil fixing plate 7 comprises a counter bore 71 and a guide groove 72, the counter bore 71 is used for placing a coil, and the guide groove 72 and the mercury slip ring 6 are used for leading out the coil; the motor 4 is fixed on the supporting mechanism 3 through a motor bracket 8; the rotating shaft 5 is fixed with the bearing support 9, and the bearing support 9 passes through the supporting mechanism 3 and is fixed on the movement adjusting mechanism 2.
As shown in fig. 4, the base mechanism 1 includes: aluminum alloy frame 11, aluminum alloy frame include two parallel arrangement's two rectangular frame, and 4 broadsides of two rectangular frame are the stand, adopt four strengthening ribs 12 of parallel arrangement to connect between two bases of two rectangular frame, and the topside and the base of at least one rectangular frame adopt strengthening rib 12 to connect, and the bottom of four stands is provided with the level (l) ing truckle respectively, but four level (l) ing truckles combination use bearing 500kg, possess the universal wheel function. The upper surface of the aluminum alloy frame is sequentially provided with the workbench 13 and the transition plate connecting plate 14 from bottom to top, the level of the workbench on the upper surface of the aluminum alloy frame can be adjusted through the rotation of the nut arranged on the horizontal adjusting caster wheel, the effect of fixing the workbench is achieved, the workbench material is made of aluminum alloy materials, and blackening treatment is performed. The workbench is processed on the processing center, and after rough processing, stress removing heat treatment is carried out, so that later deformation caused by stress generated during processing after the workbench is processed is reduced; and then clamping once again and positioning to finish the finish machining, thereby ensuring that the flatness of the upper plane of the base is 0.05 mm. The workbench is connected with the aluminum alloy frame and fastened by copper screws.
As shown in fig. 5, the movement adjusting mechanism 2 includes: two fixed brackets 21, a moving plate 22, a fixed base 23 and a precise manual angle station 24; the two fixing brackets 21 are respectively arranged at two sides below the supporting mechanism 3, and the two fixing brackets 21 are connected through a moving plate 22; a fixed base 23 and a precision manual angular position table 24 are provided at an intermediate position of the support mechanism 3. Wherein, accurate manual angle platform 24 provides the small-angle rotation regulation, adopts the vice drive of accurate worm gear, and the location is accurate, hand wheel locking. Angle range: ± 10 °, minimum reading: 5', minimum scale: 1 deg.
The bottoms of the two fixing supports 21 and the fixing bases 23 are fixed on the transition plate connecting plate 14 of the base mechanism 1, and the moving plate 22 can be adjusted to move up and down along the two fixing bases 23 through the precise manual angular table 24, so that the rotating shaft 5 above the supporting mechanism 3 is driven to move up and down to adjust the position of the rotating shaft.
Further, as shown in fig. 6, the moving plate 22 is provided with 3 positioning mechanisms 221, and the positioning mechanisms 221 include positioning holes 2211 and positioning edges 2212 provided on the sides of the positioning holes 2211; the 3 positioning holes 2211 are respectively used for installing the motor support 8 and the two bearing supports 9; the moving plate 22 is also provided with a weight-reducing groove 222. Specifically, 3 positioning holes 2211 and matching positioning edges 2212 are designed on the moving plate 22 to ensure that the mounting positions of the motor bracket 8 and the bearing bracket 9 are accurate.
Wherein, the motor support 8 and the bearing support 9 are processed on the processing center, and the processing is finished by one-time clamping and one-time positioning. The central shaft at the lower side of the motor support 8 is aligned with the positioning hole of the moving plate 22, and the edge of the motor support 8 is clamped on the corresponding positioning edge 2212 on the moving plate 22 and is fixedly connected with the positioning edge by copper screws. The central axes of the lower sides of the two bearing supports 9 are aligned with the positioning holes of the moving plate 22, and the edges of the motor supports 8 are clamped on the corresponding positioning edges 2212 on the moving plate 22 and are fixedly connected by copper screws.
As shown in fig. 7, all parts of the supporting mechanism 3 are made of aluminum alloy 6061, and the connection between the parts is fastened by copper screws. The support mechanism 3 includes: 1 supporting platform 31, 4 supporting upright posts 32 and 4 permanent magnet standard field cushion blocks 33; the supporting platform 31 and the transition plate connecting plate 14 are arranged in parallel; the 4 supporting upright columns 32 are respectively arranged between the transition plate connecting plate 14 and the supporting platform 31; 4 permanent magnetic standard field cushion blocks 33 are arranged on the supporting platform 31 in parallel; the arrangement directions of the 4 support columns 32 and the arrangement directions of the 4 permanent magnet standard field cushion blocks 33 are perpendicular to each other; two through holes are further formed in two sides of the 4 permanent magnet standard field cushion blocks 33, and the two bearing supports 9 respectively penetrate through the two through holes to be fixed on the moving plate 22. 4 permanent magnet standard field cushion blocks 33 can ensure that the horizontal direction of the magnetic field is parallel to the supporting platform 31. The supporting mechanism 3 is processed on the processing center, after rough processing, stress removing heat treatment is carried out, and later deformation caused by stress generated during processing after the processing of the workbench is reduced; and then clamping once again and positioning to finish machining, and ensuring the flatness of the upper plane of the base to be 0.05 mm.
Referring to fig. 5, the rotating shaft 5 includes a right rotating shaft 51, a rotating shaft 52 and a left rotating shaft 53 connected in sequence; the output shaft of the motor, the right rotating shaft 51, the rotating shaft 52 and the left rotating shaft 53 are connected in pairs and in sequence by adopting couplings, and the left rotating shaft 553 and the right rotating shaft 51 are also connected with the bearing bracket 9 through bearings respectively; a groove matched with the coil fixing plate 7 in shape is formed in the rotating shaft 5, so that the coil fixing plate 7 is inserted into the rotating shaft 5; the left rotating shaft 53 is provided with a guide hole inside, and the coil is led out through the guide groove 72 on the coil fixing plate 7 and then led out through the guide hole inside the left rotating shaft 53.
Preferably, as shown in fig. 8, the guide groove 72 includes a first guide groove 721 and a second guide groove 722; the width of the first guide slot 721 is smaller than that of the second guide slot 722; the edge of the counterbore 71 is provided with a notch through which the first guide slot 721 communicates with the counterbore 71.
The bearing and the shaft coupling both select the model that does not contain indisputable material, and the bearing selects for use zirconia full ceramic bearing, installs epaxially about, fixes on bearing bracket with the bearing fixing base.
The zirconia all-ceramic bearing, the ferrule and the rolling body are made of zirconia (ZrO2) ceramic materials. The friction coefficient is small, the surface smoothness is good, the self-lubricating performance is good, no grease is needed to be added, and the characteristic is used for ensuring the rotation stability of the main shaft. Secondly, the whole material is metal-free and antimagnetic, is specially used in the fields of demagnetization equipment, precision instruments and the like, and can improve the measurement accuracy.
The coupler is formed by processing 7 series of aviation aluminum alloy materials, the middle plum blossom elastomer is made of imported polyurethane raw materials, the hardness is high, zero-gap transmission is achieved, the coupler belongs to non-magnetic and non-ferrous materials, the motor, the left and right shafts and the middle rotating shaft are connected together through the coupler, copper screws are used for fastening the coupler, and the coupler can move on the left rotating shaft 53 and the right rotating shaft 51 along the axis direction of the left rotating shaft and the right rotating shaft to guarantee that the middle rotating shaft 52 is convenient to disassemble.
the rotation shaft 5 functions to rotate the coil at a high rotation speed with high stability and to output an induced voltage signal. Wherein pivot 5 and coil fixed plate 7 all select for use the organic glass material, and left pivot 53 and right pivot 51 all select for use the brass material, and other parts are aluminum alloy 6061 material, all fasten with the copper screw between each spare part.
The rotating shaft 52 is made of organic glass material and has no magnetic or ferrous substance. The coil fixing plate 7 is inserted into the rotating shaft 52, and is manufactured by adopting an integral casting process in order to ensure stable and reliable rotation and have no seam. The counter bore 71 on the coil fixing plate 7 is used for placing the coil, and the lead wire of the coil is led out along the guide groove 72.
The calibration of little coil should be based on the parallel condition of the base face in coil rotation axis and permanent magnetism standard field, if there is the contained angle, will produce great influence to the calibration result, consequently, it is rotatory to drive the rotation axis through the motor, and then drives the coil rotatory in the permanent magnetism field, when the calibration little coil circle area, through the utility model discloses a device rotates the maximum value that can find average voltage.
The mercury slip ring 6 is connected with the left rotating shaft 53 through a two-core quick connector, and a coil led out from the guide groove 72 is connected with a lead of the two-core quick connector. The connecting wire of the coil is led out through the mercury slip ring 6, and the led-out wire is fixed. The mercury slip ring 6 is a two-core slip ring produced in Taiwan. The maximum speed of rotation can reach 1800 rpm. The application of the mercury slip ring 6 is one of the key factors of the success of the device, the following table shows test data obtained by adopting the mercury slip ring, and the table 1 shows that the repeatability of the average voltage is good, and the frequency is stable, so that the mercury slip ring 6 is selected to well transmit an analog alternating current signal, and the signal is not distorted at all. Through two core joint quick plug, convenient dismantlement rotation axis and coil fixing base do not have metallics except that the copper line.
TABLE 1 repeatability of mean voltage and stability of frequency
As shown in fig. 9, the calibration control device further includes: the rotation control mechanism is used for controlling the accurate movement of the rotating shaft and can set the rotating speed, the rotating direction and the rotating time length; the rotation control mechanism includes: the system comprises an alternating current power supply, a filter, an alternating current-direct current converter, a driver, a PLC, a touch screen and a filter; the alternating current power supply provides alternating current for the driver after filtering through the filter, and the driver is sequentially connected with the PLC and the touch screen; the alternating current-direct current converter is connected with the driver, and the alternating current-direct current converter converts alternating current into direct current and then provides the direct current for the driver.
The filter is used for filtering unnecessary harmonic waves in the circuit, removing interference and ensuring the accuracy and stability of the whole circuit signal; the direct current power supply supplies 24V direct current power to the servo driver, the PLC and the touch screen respectively. Besides a 24V direct current power supply, the servo driver is also connected with a single-phase 220V alternating current power supply.
The motor is an east motor AZ series AZ66 model, the motor is a pulse sequence input driver, the resolution is 1000P/R, and when the motor is set, the motor is 0.36 degree/pulse (1000 pulses are one circle), so that the positioning precision of one motion period is +0.05 degree, and when the motor is overloaded, the motor can alarm when the motor exceeds 1.8 degrees, and the motor can be automatically repaired and adjusted when the motor exceeds 1.8 degrees. The AZ66 stepping motor is more reliable by adopting a closed-loop system, and can automatically adjust even if step loss occurs. Meanwhile, the oriental motor stepping motor has better synchronism than the servo motor. The ABZO encoder is a mechanical absolute encoder without a battery, and the display rotating speed is monitored in real time. The characteristics ensure that the motor can realize the uniform and stable rotation of the rotating shaft.
The driver is matched with the oriental motor, the driver is provided with running data, and the type of the running data is selected and executed through the PLC. And the connection and control between the Modbus and the previous level are executed through the Modbus.
S7-200SMART, CPU ST20 and SIMATIC wonderful series panels are selected for the Siemens PLC and the touch screen to form an automatic control and man-machine interaction platform, so that the standard function of a man-machine interface is accurately provided, and the following functions of the display screen of the whole device are realized: 1. starting and stopping; 2. displaying the real-time running speed; 3. restoring the zero position; 4. detecting an operation setting parameter; 5. and (6) adjusting the speed.
with reference to fig. 3, the calibration control device further includes: and the protective cover 10 covers the base mechanism 1, the supporting mechanism 3, the movement adjusting mechanism 2, the motor 4, the rotating shaft 5 and the mercury slip ring 6. The protective cover 10 is made of organic glass and has two functions: 1) keep apart permanent magnetism standard field, avoid having on magnetic or the spare part of iron nature material is inhaled the magnetic field, 2) when pivot 5 high-speed rotatory, can play the effect of protection operating personnel, noise reduction.
The utility model also provides a magnetic moment measures calibrating device with little coil circle area, as shown in fig. 9, including a magnetic moment measures calibrating control device with little coil circle area, still include: a pair of permanent magnets, a nuclear magnetic resonance magnetometer, a voltmeter and a frequency meter; the N pole of one permanent magnet is opposite to the S pole of the other permanent magnet; the calibrated coil and the rotating shaft 5 are arranged between the N pole and the S pole, the nuclear magnetic resonance magnetometer is arranged on one side close to the N pole, and the voltmeter and the frequency meter are respectively connected with the mercury slip ring 6.
The utility model discloses a method of continuous rotation coil in even field calibrates the turn area, please refer to fig. 9 for the specific measurement principle. The uniform field is formed by a permanent magnet, the magnetic field is about 3000Oe, the uniform region is better than 0.01%/cm, the stability is better than 0.003%/min, a motor is used for driving a coil to rotate in the uniform field at a fixed frequency, and a voltmeter is used for measuring the induced voltage and frequency. The coil constant can be calculated according to the formula (2.1).
The design of the permanent magnetic standard field simultaneously considers factors such as the magnetic field intensity, the size of a magnetic field uniform area, the height of an air gap, the matching with the whole device and the like. In order to improve the magnetic field intensity, the permanent magnetic standard field is made of sintered NdFeB materials and is strictly designed and manufactured according to an Ansoft magnetic circuit simulation model, the permanent magnetic standard field has the central magnetic field intensity of more than 3000Oe, a permanent magnetic standard field uniform area can be shown in figure 10, the design uniformity index reaches the value shown in table 2, namely the precision of the magnetic field distribution uniformity in the diameter range of 60mm reaches 0.04%, the precision of the magnetic field distribution uniformity in the diameter range of 80mm reaches 0.1%, and the air gap is larger than 50mm, so that a rotating shaft, a coil and the like can be accommodated in the air gap.
design index of magnetic field uniformity in design of standard Oe permanent magnet field of table 23000
| Coordinate x/mm | -40 | -30 | -20 | -10 | 0 | 10 | 20 | 30 | 40 |
| Magnetic field mu0H/T | 0.33757 | 0.33741 | 0.33734 | 0.33733 | 0.33732 | 0.33733 | 0.33734 | 0.33745 | 0.33764 |
the utility model discloses a method of continuous rotation coil in even field calibrates little coil NS. The test result shows that the calibration uncertainty of the small coil NS reaches the level of 0.04%, and is obviously improved compared with the traditional method.
The magnetic field accuracy and the magnetic field uniformity are important performance indexes of a standard magnetic field and are core factors for calibration by a small coil alternating current method, the maximum error of a permanent magnetic standard field produced in foreign countries is generally in the range of 0.5% -1%, and the permanent magnetic standard field of the subject is matched with nuclear magnetic resonance for use, so that the accurate calibration of direct current magnetic flux density can be realized. The following are field homogeneity zones and homogeneity tests for a permanent magnet standard magnetic field. Table 3 shows the results of the standard magnetic field uniformity of the permanent magnet measured using a Metrolab Pt2025 NMR magnetometer at a temperature of 24.5 ℃. The uniformity test range was selected to be within 60mm diameter. From the results, it can be seen that the magnetic field uniformity is better than 0.02% in the diameter range of 40mm, which substantially completely meets the calibration requirements of small coils of all sizes and models; the magnetic field uniformity was better than 0.04% across the 60mm diameter range.
The Metrolab Pt2025 nuclear magnetic resonance magnetometer is an international universal magnetic field calibration instrument, and the accuracy is better than 5 ppm.
TABLE 3 permanent magnet Standard magnetic field homogeneity region test
The calibrated small coil outside diameter does not exceed 16mm, does not exceed the above-mentioned 10mm uniform region, and the above-mentioned uniformity can be realized by testing the space 8mm above and below the median plane of the standard magnetic field, therefore, in the application of this subject, the standard magnetic field uniformity of the permanent magnet can be defined as 0.0057%.
(2) influence of temperature on the field strength of a permanent magnet standard field
The magnetic field intensity generated by the permanent magnetic standard magnetic field is respectively tested when the environment is stabilized at 28.5 ℃ and 20 ℃, and the temperature coefficient of the obtained permanent magnetic standard magnetic field in the room temperature range is (0.1 +/-0.01)%, which is also consistent with the residual magnetism temperature coefficient of the sintered neodymium iron boron made of the material used for manufacturing the permanent magnetic standard field. And when the small coil NS is calibrated, the standard magnetic field intensity of the permanent magnet can be further determined according to the environmental temperature of a laboratory and the temperature coefficient. The standard permanent magnet magnetic field is placed in a closed indoor environment, the uncertainty of indoor temperature measurement is 0.3 ℃, and the error of the standard permanent magnet magnetic field intensity, which is obtained by correcting the standard permanent magnet magnetic field intensity due to different temperatures, is not higher than 0.003%. In the actual calibration process with higher requirement on the calibration precision, the nuclear magnetic resonance magnetometer can be used for measuring the magnetic field intensity of the standard magnetic field in real time, and the influence of the temperature on the magnetic field intensity of the standard magnetic field of the permanent magnet can be ignored.
(3) Repeatability of average voltage and stability of frequency
At the rotating speed of 1500r/Min, the average value of the induced voltage of the coil is continuously measured for ten times by using an LMG610 power meter (a voltage synchronization mode is adopted), and the alternating current frequency is measured and recorded at the same time, so that the voltage and the frequency are kept very stable, and the stability is shown in the table 1. This result can verify that the rotational speed stability of the motor can be controlled to about five per million, which is a stability exceeding one ten thousandth of the original project. In fact, if the induced voltage and the induced frequency are measured synchronously, the influence of the rotation speed fluctuation can be offset by the same-direction fluctuation of the voltage measurement value, and the influence is smaller.
(4) Determination of small coil NS
a small coil is placed in the calibration device and the coil rotation rate is set. And after the rotating speed is stable, simultaneously measuring and recording the average voltage and the rotating frequency, and determining the small coil NS according to the standard value of the magnetic field.
In the formula (I), the compound is shown in the specification,The measured average voltage is in units of V; f is measured rotational frequency in units ofHz；The magnetic flux density generated by a standard magnetic field is given in T.
And at different rotating speeds, the NS of the small coil No. 0 is measured respectively. As shown in Table 5, the NS consistency of the coil was measured to be 0.002% (standard deviation) from 300r/min to 1500r/min and from 5Hz to 25 Hz. This result shows that the NS of the coil is independent of frequency at low frequencies, verifying the scientificity and validity of the device to test. Table 5 is the NS measurements for small coil No. 0 at 28.4 degrees celsius and at different rotational speeds and table 6 is the calibration results for coils No. 1, 2, 3 and 5.
TABLE 5 NS of small coil No. 0 measured at different rotation speeds
TABLE 6 calibration results for small coils
4.3.8 uncertainty analysis of small coil NS AC calibration
(1) uncertainty uA introduced by repeatability of small coil NS measurement
As class A uncertainty, uA covers randomness differences of different testers, small coil loading and the like. In this report, it is derived from ten repeated measurements at different times. The results obtained by measuring the small coil NS through multiple rotations at the same temperature by placing the small coil in a standard magnetic field are shown in table 7 below. The results show that the repeatability of the small coil NS test is 0.009% (1 σ).
Repeatability test of small coil NS No. 74 in table
| 0.215766 | 0.215789 | 0.215805 | 0.215793 | 0.215789 |
| 0.215775 | 0.215765 | 0.215789 | 0.215745 | 0.215811 |
| ave. | 0.215783 | 1σ | 0.009％ |
(2) Uncertainty u introduced by the influence of instrumentation on the measurement resultsB，
Sources of uncertainty in Helmholtz coil constant AC calibration can be listed as follows:
a. Average voltage measurement accuracy
Under the direct input mode of LMG610 voltage, under 25Hz frequency, calibrate 8V points of power meter, the absolute value of the measurement error of average voltage is 0.02%, and the uncertainty of calibration is 0.02%, and for the measurement result of 7.55V, through the synthesis, the uncertainty of measurement of average voltage is: 0.029% (k ═ 2).
b. Partial pressure effect of small coil resistance
LMG610 input impedance 10M omega, small coil resistance 350 omega, influence neglect not calculate
c. Frequency measurement accuracy
The LMG610 is too distributed for a frequency measurement accuracy of the port input signal ± a measurement of 50 ppm.
d. Temperature characteristic of permanent magnet standard magnetic field
as described above, the error of the standard magnetic field strength of the permanent magnet, which is corrected for the standard magnetic field strength of the permanent magnet due to different temperatures, is not higher than 0.02%. In the actual calibration process with higher requirement on the calibration precision, the nuclear magnetic resonance magnetometer can be used for measuring the magnetic field intensity of the standard magnetic field in real time, and the influence of the temperature on the magnetic field intensity of the standard magnetic field of the permanent magnet can be ignored.
e. permanent magnet standard magnetic field calibration
the Metrolab Pt2025 nuclear magnetic resonance magnetometer is an international universal magnetic field calibration instrument, and the accuracy is better than 5 ppm.
f. Homogeneity of permanent magnet standard magnetic field
As mentioned before, the permanent magnet standard field is uniform by 0.0057% in the range of the small coils.
g. Verticality of small coil rotating shaft and magnetic field
After the small coil is placed in the calibrating device, the mechanical device can control the rotating shaft of the small coil to be vertical to the magnetic field, and the error can be controlled within 1 degree. The uncertainty resulting from this is less than 0.015%. In addition, the inclination angle of the coil is finely adjusted through an attitude adjusting mechanism of the calibrating device, the maximum value of the average voltage is found, and the uncertainty caused by the maximum value of the average voltage is further reduced.
h. Temperature stability of the small coil NS, performed at the same temperature
At different temperatures, the calibration of the small coil NS and the calibration of the helmholtz coil using the small coil NS are carried out at the same time in the same room, the temperature effect being negligible.
i. Influence of leakage flux of outer lead of coil
The influence of magnetic leakage flux is brought to the outer lead wire of coil, and the influence is not brought to the wire outside the mercury sliding ring because not rotating, the mode of leading wire pair twist in the mercury sliding ring makes the magnetic leakage flux positive and negative offset, and the partial area that can not offset compares for the small amount with effective circle area, and lead wire length is about 60mm, for experimental verification, has made 180mm pair twist lead wire separately and has carried out the contrast experiment, and the experimental result does not surpass the difference of little coil NS repeatability with 60mm lead wire.
(3) Evaluation of Synthesis uncertainty
The uncertainty analysis of the small coil turn area measurements is shown in table 8, according to JJF1059-1999 measurement uncertainty assessment and presentation, and the aforementioned uncertainty components are summarized in table 8. Table 8 covers the items of uncertainty source, uncertainty source index, input uncertainty value, distribution type, divsor, sensitivity coefficient, standard uncertainty (1 σ), and effective degree of freedom. The formula for calculating the standard synthetic uncertainty is embedded in table 8:
The relative expansion uncertainty of the small coil turn area measurements was thus calculated as: 0.04% (k ═ 2).
TABLE 8 Small coil NS calibration uncertainty summary table
the subject is to calibrate a small coil NS by a method of continuously rotating coils in a uniform field. The uniform field is a high-uniformity standard magnetic field made of permanent magnets, the magnetic field intensity is about 3500Oe, a high-rotating-speed stable motor is used for driving a coil to rotate at a fixed frequency in the uniform field, the stability of the rotating frequency is ensured, and a voltmeter is used for measuring the induced voltage and frequency. The small coil NS can be accurately determined according to equation 3.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (10)
1. A calibration control device for measuring the turn area of a small coil for magnetic moment is characterized by comprising: the device comprises a base mechanism (1), a movement adjusting mechanism (2) and a supporting mechanism (3) which are sequentially arranged from bottom to top, wherein a motor (4), a rotating shaft (5) and a mercury slip ring (6) are arranged above the supporting mechanism (3);
One end of the rotating shaft (5) is connected with an output shaft of the motor (4), and the other end of the rotating shaft is connected with the mercury slip ring (6);
A coil fixing plate (7) is arranged in the rotating shaft (5), the coil fixing plate (7) comprises a counter bore (71) and a guide groove (72), and a coil is placed in the counter bore (71) and led out through the guide groove (72) and the mercury slip ring (6);
the motor (4) is fixed on the supporting mechanism (3) through a motor bracket (8);
the rotating shaft (5) is fixed with the bearing support (9), and the bearing support (9) penetrates through the supporting mechanism (3) and is fixed on the movement adjusting mechanism (2).
2. The calibration control device according to claim 1, wherein the spindle (5) comprises a right spindle (51), a rotation axis (52), and a left spindle (53) connected in sequence;
The left rotating shaft (53) and the right rotating shaft (51) are respectively connected with the bearing support (9) through bearings;
A groove (521) matched with the shape of the coil fixing plate (7) is formed in the rotating shaft (52), so that the coil fixing plate (7) is inserted into the rotating shaft (52);
A guide hole is formed in the left rotating shaft (53), and the coil is led out through the guide hole after being led out through the guide groove (72).
3. Calibration control device according to claim 2, characterized in that the mercury slip ring (6) is connected to the left shaft (53) by means of a two-core quick connector, and the coil led out from the guide hole is connected to the lead of the two-core quick connector.
4. The calibration control device according to claim 1, wherein the movement adjusting mechanism (2) comprises: two fixed brackets (21), a moving plate (22), a fixed base (23) and a precise manual angular table (24);
the two fixing supports (21) are respectively arranged at two sides below the supporting mechanism (3), and the two fixing supports (21) are connected through a moving plate (22);
the fixed base (23) and the precise manual angular table (24) are arranged in the middle of the supporting mechanism (3).
5. the calibration control device according to claim 4, wherein the moving plate (22) is provided with 3 positioning mechanisms (221), and the positioning mechanisms (221) comprise positioning holes (2211) and positioning edges (2212) arranged at the sides of the positioning holes (2211); the 3 positioning holes (2211) are respectively used for installing the motor bracket (8) and the two bearing brackets (9);
The moving plate (22) is also provided with a weight reduction groove (222).
6. The calibration control device according to claim 4, wherein the support mechanism (3) comprises: 1 supporting platform (31), 4 supporting upright posts (32) and 4 permanent magnet standard field cushion blocks (33);
the supporting platform (31) is arranged in parallel with the upper surface of the base mechanism (1);
The 4 supporting upright columns (32) are respectively arranged between the upper surface of the base mechanism (1) and the supporting platform (31);
The 4 permanent magnet standard field cushion blocks (33) are arranged on the supporting platform (31) in parallel; the arrangement direction of the 4 support columns (32) is vertical to the arrangement direction of the 4 permanent magnetic standard field cushion blocks (33);
Two through holes are further formed in two sides of the 4 permanent magnet standard field cushion blocks (33), and the two bearing supports (9) penetrate through the two through holes respectively and are fixed on the moving plate (22).
7. The calibration control device of claim 1, further comprising: a rotation control mechanism;
the rotation control mechanism includes: the system comprises an alternating current power supply, a filter, an alternating current-direct current converter, a driver, a PLC, a touch screen and a filter;
The alternating current power supply provides alternating current for the driver after filtering through the filter, and the driver is sequentially connected with the PLC and the touch screen;
the alternating current-direct current converter is connected with the driver, and the alternating current-direct current converter converts alternating current into direct current and then provides the direct current for the driver.
8. the calibration control device of claim 1, wherein the guide slot (72) comprises a first guide slot (721) and a second guide slot (722);
The width of the first guide slot (721) is smaller than that of the second guide slot (722);
The edge of the counter bore (71) is provided with a notch, and the first guide groove (721) is communicated with the counter bore (71) through the notch.
9. The calibration control device of claim 1, further comprising: and the protective cover (10) covers the base mechanism (1), the movement adjusting mechanism (2), the supporting mechanism (3), the motor (4), the rotating shaft (5) and the mercury slip ring (6) externally.
10. a device for calibrating the turn area of a small coil for measuring magnetic moment, comprising the device for calibrating and controlling the turn area of a small coil for measuring magnetic moment according to any one of claims 1 to 9, further comprising: a pair of permanent magnets, a nuclear magnetic resonance magnetometer, a voltmeter and a frequency meter;
The N pole of one permanent magnet is opposite to the S pole of the other permanent magnet;
The calibrated small coil and the rotating shaft (5) are arranged between the N pole and the S pole, and the nuclear magnetic resonance magnetometer is arranged on one side close to the N pole;
the voltmeter and the frequency meter are respectively connected with the mercury slip ring.
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