CN111965574B - Closed-loop soft magnetic material direct current magnetic performance measuring method - Google Patents
Closed-loop soft magnetic material direct current magnetic performance measuring method Download PDFInfo
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Abstract
The invention discloses a closed-loop soft magnetic material direct current magnetic performance measuring method, which comprises the following steps: A. demagnetizing the sample with attenuation amplitude; B. carrying out forward and reverse amplification impact magnetization on the sample according to a set Hset, judging the stability by a microcomputer, and then taking (B, H) values and connecting all points to obtain a basic magnetization curve; C. the positive and negative impact is carried out until the maximum value Hs of the magnetic field intensity, and the magnetic flux obtains the value Bs on average; D. magnetically exercising for a period under Hs condition, impacting to + Hs → Hset, intelligently judging the value (B, H) under stable condition by a microcomputer, completing the measurement from Hs to-Hs points and connecting to obtain a magnetic hysteresis loop descending branch; E. and performing symmetrical negation operation on the magnetic hysteresis loop descending branch to obtain a magnetic hysteresis loop ascending branch, and obtaining a complete direct current magnetic hysteresis loop. The invention completely starts from the definition of testing the soft magnetic direct current magnetic performance by an impact method, automatically completes the measurement of a magnetization curve and a magnetic hysteresis loop, does not need artificial interference, and has accurate test data and high efficiency.
Description
Technical Field
The invention relates to the technical field of environment-friendly equipment, in particular to a closed-loop soft magnetic material direct current magnetic property measuring method.
Background
Theoretical research and industrial application of metallic soft magnetic materials are of vital importance, and it is naturally necessary to know their intrinsic parameters. However, their experimental evaluation is not easy, since the measured data also depends on the method behind the measuring device. Such as: in the conventional measurement of the direct current magnetic performance parameters of closed circuit samples of soft magnetic materials, the repeatability of the data depends on the level of the fluxmeter and the current source, but it is more necessary to master the correct test method, otherwise many problems arise.
Among the existing standards are: IEC 64004-4, IEC 64004-7, ASTM A341, A342, GB/T13012-2008 and the like only roughly describe the measurement process of a scanning method or an impact method, wherein the description of the impact method still remains on the description of the traditional classic impact method book, or the magnetic measurement theory is not really understood, particularly how to control the impact speed and the acquisition value time, the influence of eddy current damping in the metal soft magnetic measurement process is eliminated, and the larger difference of the test data becomes a normal state.
As a large country for producing and applying magnetic materials, China needs to do the work of measuring the soft magnetic direct current characteristics, which is beneficial to providing accurate measurement data for the basic research of the industries such as new materials, automobiles, war industry, communication, intelligent manufacturing and the like in China. The development history of the method for measuring the direct-current magnetic property of the Chinese soft magnetic material is a process which approaches the direct-current magnetic property of the material by one step:
before 1980 s, the DC magnetic performance of soft magnetic material was measured by the classic impact method, which is a magnetic material DC magnetic measurement classic method defined by definition! The key of direct current magnetic measurement of the impact method is accurate measurement of delta B, an impact galvanometer is adopted at first, the application of the classical measurement method is limited by inertia integration, the speed is low, the precision is low, and the method is still unique in principle!
In 1990 s, under the leadership of the national institute of metrology science and technology, leading the institute of electronic research in the area of the bottom of the barrel of Hunan province, a microcomputer, a D/A converter, an excitation current generator and an integrator were organically combined, so that the method for testing the initial magnetization curve by using the simulation impact method and the method for testing the hysteresis loop by using the scanning method were realized, the initial permeability ui and the maximum permeability um repeatability of the tested material were greatly improved, the process was qualitative, the test result was also close to the correct direction, and the method for testing the hysteresis loop by using the simulation impact method was still lagged behind due to the current excitation current generator and the hysteresis integrator, the test repeatability was poor, and it was difficult to measure the hysteresis loop and related parameters.
In the 2000 s, represented by the Olympic science and technology Co., Ltd. of Hunan province, a hysteresis loop method for testing the direct current magnetic performance of the soft magnetic material by adopting a simulation impact method is realized, the repeatability of a test loop and parameters is improved, the direct current magnetic performance test requirement of the low eddy current damping soft magnetic material is basically met, the method belongs to a qualitative mode, and the direct current magnetic performance is obtained by controlling the impact period of different materials.
In 2010, represented by Yongyi science and technology limited in Hunan province, the simulation impact method is further advanced one step, and the main core technology is that a microcomputer is adopted to intelligently execute a circular impact magnetization curve and a magnetic hysteresis loop until the difference between the result and the impact result in the previous period is less than 0.3%, so that the direct current magnetic performance result of the material is determined to be obtained, and the national invention patent is firstly applied. The measuring method calculates the quantity, can reduce the test deviation to a smaller range, but the test time is relatively longer, mainly because the waiting time of the test invalid point is too long, and each measurement needs to be carried out one cycle and then the next cycle of test comparison is carried out.
Disclosure of Invention
The invention provides a closed-loop soft magnetic material direct current magnetic performance measuring method, and aims to solve the technical problems of long measuring time and poor trueness and accuracy of a test result in the existing impact method.
The technical scheme adopted by the invention is as follows:
a closed loop soft magnetic material direct current magnetic performance measuring method comprises the following steps:
A. demagnetizing the closed-loop soft magnetic material under the set maximum current gear to the set minimum current gear;
B. the sample is excited in the forward direction and the reverse direction according to a set magnetic field intensity Hset until the magnetic field intensity Hs reaches the maximum, trapezoidal excitation waveforms are adopted after each Hset point is reached, the magnetic flux is intelligently judged by a microcomputer and then is collected, the value of + B and-B is obtained, the value of B is obtained by taking the average value of the value of + B and-B, and the value of (B, H) connecting each test point is connected to obtain a basic magnetization curve;
C. obtaining the Bs value of the closed-loop soft magnetic material through the average magnetic flux value obtained by positively and reversely charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity Hs;
D. firstly, the magnetic field intensity is increased to the maximum magnetic field intensity Hs, then the magnetic field intensity is decreased to the set magnetic field intensity Hset, the acquired stable magnetic flux value is intelligently judged by a microcomputer until the measurement of each point from Hs to-Hs is carried out, the magnetic flux of all test points is ensured to be obtained under the stable condition, and the (B, H) of each test point is connected to obtain a hysteresis loop descending branch curve;
E. and performing symmetrical negation operation on the excitation magnetic field value and the Hset value of the magnetic hysteresis loop descending branch curve to obtain a magnetic hysteresis loop ascending branch curve, thereby obtaining a complete direct-current magnetic hysteresis loop.
Further, the step a specifically includes the steps of:
calculating a maximum current gear used in the test process according to the maximum magnetic field intensity Hs set before the test;
adopting a sine wave with a set period, a waveform frequency and a waveform peak value decreasing coefficient as a demagnetization waveform to demagnetize the closed-loop soft magnetic material under the maximum current gear;
if a current gear smaller than the maximum current gear exists, the current gears are sequentially changed into a current gear smaller by one, and a sine wave with a set period, a waveform frequency and a waveform peak value decreasing coefficient is used as a demagnetization waveform to demagnetize the closed-loop soft magnetic material;
and if the current gear is the minimum current gear, finishing demagnetization.
Furthermore, the set number of cycles is more than 50, the waveform frequency is not higher than 10Hz, the peak value of the first sine wave is the maximum magnetic field intensity Hs, and the successive waveform peak values take 0.9 as a decreasing coefficient.
Further, the step C specifically includes the steps of:
positively charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity Hs and collecting the current magnetic flux value Fval 1;
reversely charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity-Hs and collecting the current magnetic flux value Fval 2;
and (3) calculating the Bs (saturation magnetic flux) value of the closed-loop soft magnetic material:
Bs＝(Fval1-Fval2)/(2*N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
Further, when the magnetic field intensity of the closed-loop soft magnetic material is positively charged to the maximum magnetic field intensity Hs and the magnetic field intensity of the closed-loop soft magnetic material is reversely charged to the maximum magnetic field intensity-Hs, the magnetic field intensity is kept for more than 200 ms.
Further, the step B specifically includes the steps of:
after a closed-loop soft magnetic material is subjected to magnetic exercise for one period, the magnetic field intensity is charged to a set magnetic field intensity Hset in the positive direction;
collecting magnetic flux values once at set time intervals, and taking the magnetic flux value of the measuring point as a positive stable magnetic flux value until the change rate of the magnetic flux values of two adjacent times is less than one thousandth;
charging the magnetic field intensity to a reverse set magnetic field intensity-Hset;
collecting magnetic flux values once at set time intervals, and taking the magnetic flux value of the measuring point as a reverse stable magnetic flux value until the change rate of the magnetic flux values of two adjacent times is less than one thousandth;
and averaging the difference between the obtained positive stable magnetic flux value and the obtained negative stable magnetic flux value, converting the difference into a B value to obtain a B value corresponding to Hset, and connecting the (B, H) values of all the test points to obtain a basic magnetization curve.
Further, the step D specifically includes the steps of:
in the section Hs to 0 of the magnetic field intensity waveform, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, calculating a B value at the Hset position in the section Hs to 0 according to a stable magnetic flux value acquired according to a set time interval;
in the section from 0 to-Hs of the magnetic field intensity waveform, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, calculating to obtain a B value at the Hset position in the section from 0 to-Hs according to a stable magnetic flux value acquired according to a set time interval;
and obtaining a hysteresis loop descending branch curve according to the B value at the Hset position in the Hs to 0 section and the B value at the Hset position in the 0 to-Hs section.
Further, in the case that the magnetic field strength is charged to the maximum magnetic field strength Hs and the set magnetic field strength Hset in the section Hs to 0 of the magnetic field strength waveform, the B value at the Hset position in the section Hs to 0 is calculated according to the stable magnetic flux value acquired according to the set time interval, which specifically comprises the following steps:
in the section Hs to 0 of the magnetic field intensity waveform, performing magnetic exercise for a period on the closed-loop soft magnetic material, filling the magnetic field intensity to the maximum magnetic field intensity Hs and keeping the magnetic field intensity for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 3;
charging the magnetic field intensity to a set magnetic field intensity Hset;
collecting magnetic flux values at set time intervals, and recording the magnetic flux value of the measuring point as Fval4 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
b value at Hset in Hs to 0 segment is calculated:
B＝Bs-(Fval3–Fval4)/(N2*Ae)
where N2 is the number of turns of the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
Further, in the case that the magnetic field intensity is charged to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset in the section 0 to-Hs of the magnetic field intensity waveform, the B value at the Hset position in the section 0 to-Hs is calculated according to the stable magnetic flux value acquired according to the set time interval, which specifically comprises the steps of:
carrying out a period of magnetic exercise on the closed-loop soft magnetic material, and filling the magnetic field intensity to the maximum magnetic field intensity Hs;
charging the magnetic field intensity to a set magnetic field intensity Hset;
collecting magnetic flux values at set time intervals, and recording the magnetic flux value of the measuring point as Fval5 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
reversely charging the magnetic field intensity to a set magnetic field intensity-Hset for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 6;
b values at Hset in the segments 0 to-Hs are calculated:
B＝Bs-(Fval5–Fval6)/(N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
Further, the set time interval is 100ms to 500 ms.
The invention has the following beneficial effects:
the closed-loop soft magnetic material direct current magnetic performance measuring method adopts an intelligent control method on the basis of the existing impact method, continuously measures the magnetic flux value of each measuring point until the change rate of the measured point in a set time interval is less than one thousandth, and takes the stabilized value as the DC value of the measured point; compared with the existing impact method, the impact method introduces an intelligent control method, does not need to set waiting time, can automatically change the delay time according to the change rate of the magnetic flux value, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect of different testing results caused by different setting waiting times, and ensures that the testing result is more real and accurate.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of a closed-loop method for measuring the DC magnetic performance of the soft magnetic material according to the preferred embodiment of the invention.
Fig. 2 is a diagram showing the waveform of the variation of the magnetic field intensity used for the magnetization curve measurement according to the preferred embodiment of the present invention.
Fig. 3 is a waveform diagram illustrating the variation of magnetic field strength from Hs to 0 segment in accordance with the preferred embodiment of the present invention.
FIG. 4 is a diagram illustrating the waveform of the variation of magnetic field intensity from 0 to-Hs according to the preferred embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1, a preferred embodiment of the present invention provides a closed-loop soft magnetic material dc magnetic performance measurement method, including the steps of:
s1, demagnetizing the closed-loop soft magnetic material under the set maximum current gear to minimum current gear;
s2, exciting the sample according to the set magnetic field intensity Hset to the maximum magnetic field intensity Hs, adopting trapezoidal excitation waveform after reaching each Hset point, intelligently judging the magnetic flux through a microcomputer, collecting the magnetic flux after being stable, obtaining the values of + B and-B, obtaining the value B by taking the average value of the values of + B and-B, and connecting the values of (B, H) of each test point to obtain a basic magnetization curve;
s3, obtaining the Bs value of the closed loop soft magnetic material through the average magnetic flux value obtained by charging the magnetic field intensity of the closed loop soft magnetic material to the maximum magnetic field intensity Hs in the positive and reverse directions;
s4, firstly, the magnetic field strength is increased to the maximum magnetic field strength Hs, then the magnetic field strength is decreased to the set magnetic field strength Hset, the acquired stable magnetic flux value is intelligently judged by a microcomputer until the measurement of each point from Hs to-Hs is carried out, the magnetic flux of all the test points is ensured to be obtained under the stable condition, and the (B, H) of each test point is connected to obtain a hysteresis loop descending branch curve;
s5, symmetrically inverting the excitation magnetic field value and the Hset value of the magnetic hysteresis loop descending branch curve to obtain a magnetic hysteresis loop ascending branch curve, and thus obtaining a complete direct-current magnetic hysteresis loop.
The closed-loop soft magnetic material direct current magnetic performance measuring method of the embodiment adopts an intelligent control method on the basis of the existing impact method, continuously measures the magnetic flux value of each measuring point, and takes the stabilized value as the DC value of the measured point until the change rate of the measured point in a set time interval is less than one thousandth; compared with the existing impact method, the impact method introduces an intelligent control method, does not need to set waiting time, can automatically change the delay time according to the change rate of the magnetic flux value, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect of different testing results caused by different setting waiting times, and ensures that the testing result is more real and accurate.
In a preferred embodiment of the present invention, the step S1 specifically includes the steps of:
s11, calculating the maximum current gear used in the test process according to the maximum magnetic field intensity Hs set before the test;
s12, demagnetizing the closed-loop soft magnetic material by taking the sine wave with the set period, the waveform frequency and the waveform peak value decrement coefficient as a demagnetization waveform under the maximum current gear;
s13, if a current gear smaller than the maximum current gear exists, the current gear which is sequentially changed into a smaller one-stage current gear adopts a sine wave with a set period, a waveform frequency and a waveform peak value decreasing coefficient as a demagnetization waveform to demagnetize the closed-loop soft magnetic material, if the current gear which is changed into the smaller one-stage current gear, the sine wave with the waveform frequency not higher than 10Hz and the peak value decreasing with a 0.9 proportionality coefficient is continuously demagnetized, and at the moment, the peak value of the first sine wave is changed into the maximum magnetic field intensity Hs/10;
and S14, finishing demagnetization when the current gear is the minimum current gear.
In the embodiment, the sine wave with the set period, the waveform frequency and the waveform peak value decreasing coefficient is adopted as the demagnetization waveform to demagnetize the closed-loop soft magnetic material under the multi-gear current from the maximum current gear to the minimum current gear, and compared with the method that only one current gear is adopted to demagnetize the closed-loop soft magnetic material, the embodiment can obtain a better demagnetization effect.
In a preferred embodiment of the present invention, the set number of cycles is 50 or more, and the waveform frequency is not higher than 10Hz, which is suitable for meeting the requirement of soft magnetic demagnetization of metal. The peak value of the first sine wave is the maximum magnetic field intensity Hs, 0.9 is used as a decreasing coefficient between subsequent waveform peak values, the decreasing amplitude is not large, and simultaneously, through multi-period attenuation, a demagnetization point is ensured to be within a Rayleigh region range required by a material.
As shown in fig. 2, in a preferred embodiment of the present invention, the step S2 specifically includes the steps of:
s21, after magnetic exercise is carried out on the closed loop soft magnetic material for one period, the magnetic field strength is charged to a positive set magnetic field strength Hset;
s22, collecting magnetic flux values at set time intervals, and taking the magnetic flux value of the measuring point as a positive stable magnetic flux value when the change rate of the magnetic flux values at two adjacent times is less than one per thousand;
s23, charging the magnetic field intensity to the set magnetic field intensity-Hset in the reverse direction;
s24, collecting magnetic flux values at set time intervals, and taking the magnetic flux value of the measuring point as a reverse stable magnetic flux value until the change rate of the magnetic flux values at two adjacent times is less than one per thousand;
and S25, averaging the difference between the obtained positive stable magnetic flux value and the obtained negative stable magnetic flux value, and converting the average value into a B value to obtain the B value corresponding to Hset, namely the basic magnetization curve of the closed-loop soft magnetic material.
When a basic magnetization curve of a closed-loop soft magnetic material is detected, an intelligent control method is adopted to continuously measure a magnetic flux value of each measuring point until the change rate of the measured point in a set time interval is less than one thousandth, and the stabilized magnetic flux value is used as a stabilized magnetic flux value of the measured point; compared with the prior art, the method does not need to set waiting time, can automatically change the delay time according to the change rate of the magnetic flux value, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect that the testing results of the basic magnetization curves are different due to different setting waiting times, and ensures that the testing results of the basic magnetization curves are more real and accurate.
In a preferred embodiment of the present invention, the step S3 specifically includes the steps of:
s31, positively charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity Hs and collecting the current magnetic flux value Fval 1;
s32, reversely charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity-Hs and collecting the current magnetic flux value Fval 2;
s33, calculating the Bs value of the closed-loop soft magnetic material:
Bs＝(Fval1-Fval2)/(2*N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
The Bs value of this example was obtained under completely stable conditions, compared to the existing impact method. In the preferred embodiment of the invention, the magnetic field intensity of the closed-loop soft magnetic material is positively charged to the maximum magnetic field intensity Hs, and the magnetic field intensity of the closed-loop soft magnetic material is reversely charged to the maximum magnetic field intensity-Hs, the time required by sampling and judging the B value by a microcomputer for a metal solid ring with large eddy current damping until the B value is stable does not exceed 200ms, and the points Hs and-Hs are selected to be kept for more than 200ms in order to simplify test software.
In a preferred embodiment of the present invention, the step S4 specifically includes the steps of:
s41, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset in the section Hs to 0 of the magnetic field intensity waveform, calculating the B value of the Hset position in the section Hs to 0 according to the stable magnetic flux value acquired according to the set time interval;
s42, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset in the section 0 to-Hs of the magnetic field intensity waveform, calculating the B value at the Hset position in the section 0 to-Hs according to the stable magnetic flux value acquired according to the set time interval;
s43, obtaining a hysteresis loop descending branch curve according to the B value at Hset in the Hs to 0 section and the B value at Hset in the 0 to-Hs section.
In this embodiment, when the magnetic hysteresis loop descending branch curve is detected, by adopting an intelligent control method, in sections Hs to 0 of the magnetic field intensity waveform and sections 0 to-Hs of the magnetic field intensity waveform, stable magnetic flux values are respectively acquired according to a set time interval to calculate a B value of Hset in each section of the magnetic field intensity waveform, and finally, the magnetic hysteresis loop descending branch curve is obtained according to each B value. In the embodiment, each measuring point is continuously measured with a magnetic flux value until the measured point acquires a stabilized magnetic flux value at a set time interval as a stabilized magnetic flux value of the measured point; compared with the prior art, the embodiment does not need to set the waiting time, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect that the basic magnetization curve testing result is different due to different setting waiting times, so that the testing result of the magnetic hysteresis loop descending curve is more real and accurate.
As shown in fig. 3, in a preferred embodiment of the present invention, the step S41 specifically includes the steps of:
s411, performing magnetic exercise on the closed-loop soft magnetic material for one period in a segment Hs to 0 of the magnetic field intensity waveform, filling the magnetic field intensity to the maximum magnetic field intensity Hs, keeping the magnetic field intensity for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 3;
s412, charging the magnetic field intensity to a set magnetic field intensity Hset;
s413, collecting the magnetic flux value once at set time intervals, and recording the magnetic flux value of the measuring point as Fval4 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
s414, calculating to obtain a B value of Hset in the segment Hs to 0:
B＝Bs-(Fval3–Fval4)/(N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
In this embodiment, when the value B at the Hset position in the section Hs to 0 is obtained through calculation, after the magnetic field strength is charged to the set magnetic field strength Hset by using an intelligent control method, a magnetic flux value is continuously measured at each measurement point until the change rate of the measured point within the set time interval is less than one thousandth, and the stabilized magnetic flux value is used as the stabilized magnetic flux value of the measured point; compared with the prior art, the embodiment does not need to set the waiting time, can automatically change the delay time according to the change rate of the magnetic flux value, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect of different testing results caused by different setting waiting times, and enables the B value testing result of Hset position in the section Hs to 0 to be more true and accurate.
As shown in fig. 4, in a preferred embodiment of the present invention, the step S42 specifically includes the steps of:
s421, performing a period of magnetic exercise on the closed-loop soft magnetic material, and filling the magnetic field intensity to the maximum magnetic field intensity Hs;
s422, charging the magnetic field intensity to a set magnetic field intensity Hset;
s423, collecting the magnetic flux value once at set time intervals, and recording the magnetic flux value of the measuring point as Fval5 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
s424, reversely charging the magnetic field intensity to set magnetic field intensity-Hset and keeping the magnetic field intensity for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 6;
s425, calculating to obtain a B value at Hset in sections 0 to-Hs:
B＝Bs-(Fval5–Fval6)/(N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
In the embodiment, when the value B at the Hset position in the section from 0 to-Hs is obtained through calculation, after the magnetic field strength is filled to the set magnetic field strength Hset by adopting an intelligent control method, each measuring point is continuously measured for the magnetic flux value until the change rate of the measured point in the set time interval is less than one thousandth, and the stabilized magnetic flux value is taken as the stabilized magnetic flux value of the measured point; compared with the prior art, the embodiment does not need to set the waiting time, can automatically change the delay time according to the change rate of the magnetic flux value, not only reduces unnecessary waiting time and greatly improves the testing efficiency, but also eliminates the defect of different testing results caused by different setting waiting times, and enables the B value testing result at the Hset position in the section from 0 to-Hs to be more real and accurate.
Preferably, in the above embodiment, the set time interval is 100ms to 500ms, and preferably 200ms, so as to avoid that the B value obtained when the test time is too short is not stable, and the test efficiency is reduced due to too long time.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A closed loop soft magnetic material direct current magnetic performance measuring method is characterized by comprising the following steps:
A. demagnetizing the closed-loop soft magnetic material under the set maximum current gear to the set minimum current gear;
B. the sample is excited in the forward direction and the reverse direction according to a set magnetic field intensity Hset until the magnetic field intensity Hs reaches the maximum, trapezoidal excitation waveforms are adopted after each Hset point is reached, the magnetic flux is intelligently judged by a microcomputer and then is collected, the value of + B and-B is obtained, the value of B is obtained by taking the average value of the value of + B and-B, and the value of (B, H) connecting each test point is connected to obtain a basic magnetization curve;
C. obtaining the Bs value of the closed-loop soft magnetic material through the average magnetic flux value obtained by positively and reversely charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity Hs;
D. firstly, the magnetic field intensity is increased to the maximum magnetic field intensity Hs, then the magnetic field intensity is decreased to the set magnetic field intensity Hset, the acquired stable magnetic flux value is intelligently judged by a microcomputer until the measurement of each point from Hs to-Hs is carried out, the magnetic flux of all test points is ensured to be obtained under the stable condition, and the (B, H) of each test point is connected to obtain a hysteresis loop descending branch curve;
E. and performing symmetrical negation operation on the excitation magnetic field value and the Hset value of the magnetic hysteresis loop descending branch curve to obtain a magnetic hysteresis loop ascending branch curve, thereby obtaining a complete direct-current magnetic hysteresis loop.
2. The closed-loop soft magnetic material direct current magnetic property measurement method according to claim 1, wherein the step a specifically comprises the steps of:
calculating a maximum current gear used in the test process according to the maximum magnetic field intensity Hs set before the test;
adopting a sine wave with a set period, a waveform frequency and a waveform peak value decreasing coefficient as a demagnetization waveform to demagnetize the closed-loop soft magnetic material under the maximum current gear;
if a current gear smaller than the maximum current gear exists, the current gears are sequentially changed into a current gear smaller by one, and a sine wave with a set period, a waveform frequency and a waveform peak value decreasing coefficient is used as a demagnetization waveform to demagnetize the closed-loop soft magnetic material;
and if the current gear is the minimum current gear, finishing demagnetization.
3. The closed-loop soft magnetic material DC magnetic property measuring method according to claim 2,
the set number of cycles is more than 50, the waveform frequency is not higher than 10Hz, the peak value of the first sine wave is the maximum magnetic field intensity Hs, and the successive waveform peak values take 0.9 as a decreasing coefficient.
4. The closed-loop soft magnetic material direct current magnetic property measurement method according to claim 1, wherein the step C specifically comprises the steps of:
positively charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity Hs and collecting the current magnetic flux value Fval 1;
reversely charging the magnetic field intensity of the closed-loop soft magnetic material to the maximum magnetic field intensity-Hs and collecting the current magnetic flux value Fval 2;
calculating the Bs value of the closed-loop soft magnetic material:
Bs＝(Fval1-Fval2)/(2*N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
5. The closed-loop soft magnetic material DC magnetic property measuring method according to claim 4,
when the magnetic field intensity of the closed-loop soft magnetic material is positively charged to the maximum magnetic field intensity Hs and the magnetic field intensity of the closed-loop soft magnetic material is reversely charged to the maximum magnetic field intensity-Hs, the magnetic field intensity is kept for more than 200 ms.
6. The closed-loop soft magnetic material direct current magnetic property measurement method according to claim 1, wherein the step B specifically comprises the steps of:
after a closed-loop soft magnetic material is subjected to magnetic exercise for one period, the magnetic field intensity is charged to a set magnetic field intensity Hset in the positive direction;
collecting magnetic flux values once at set time intervals, and taking the magnetic flux value of the measuring point as a positive stable magnetic flux value until the change rate of the magnetic flux values of two adjacent times is less than one thousandth;
charging the magnetic field intensity to a reverse set magnetic field intensity-Hset;
collecting magnetic flux values once at set time intervals, and taking the magnetic flux value of the measuring point as a reverse stable magnetic flux value until the change rate of the magnetic flux values of two adjacent times is less than one thousandth;
and averaging the difference between the obtained positive stable magnetic flux value and the obtained negative stable magnetic flux value, converting the difference into a B value to obtain a B value corresponding to Hset, and connecting the (B, H) values of all the test points to obtain a basic magnetization curve.
7. The closed-loop soft magnetic material direct current magnetic property measurement method according to claim 1, wherein the step D specifically comprises the steps of:
in the section Hs to 0 of the magnetic field intensity waveform, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, calculating a B value at the Hset position in the section Hs to 0 according to a stable magnetic flux value acquired according to a set time interval;
in the section from 0 to-Hs of the magnetic field intensity waveform, under the condition that the magnetic field intensity is charged to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, calculating the B value at the Hset position in the section from 0 to-Hs according to the stable magnetic flux value acquired according to the set time interval;
and obtaining a hysteresis loop descending branch curve according to the B value at the Hset position in the Hs to 0 section and the B value at the Hset position in the 0 to-Hs section.
8. The closed-loop soft magnetic material DC magnetic property measuring method according to claim 7,
in the section Hs to 0 of the magnetic field intensity waveform, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, the B value of the Hset position in the section Hs to 0 is obtained by calculating according to the stable magnetic flux value acquired according to the set time interval, and the method specifically comprises the following steps:
in the section Hs to 0 of the magnetic field intensity waveform, performing magnetic exercise for a period on the closed-loop soft magnetic material, filling the magnetic field intensity to the maximum magnetic field intensity Hs and keeping the magnetic field intensity for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 3;
charging the magnetic field intensity to a set magnetic field intensity Hset;
collecting magnetic flux values at set time intervals, and recording the magnetic flux value of the measuring point as Fval4 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
b value at Hset in Hs to 0 segment is calculated:
B＝Bs-(Fval3–Fval4)/(N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
9. The closed-loop soft magnetic material DC magnetic property measuring method according to claim 7,
in the section from 0 to-Hs of the magnetic field intensity waveform, under the condition that the magnetic field intensity is filled to the maximum magnetic field intensity Hs and the set magnetic field intensity Hset, the B value at the Hset position in the section from 0 to-Hs is obtained by calculation according to the stable magnetic flux value acquired according to the set time interval, and the method specifically comprises the following steps:
carrying out a period of magnetic exercise on the closed-loop soft magnetic material, and filling the magnetic field intensity to the maximum magnetic field intensity Hs;
charging the magnetic field intensity to a set magnetic field intensity Hset;
collecting magnetic flux values at set time intervals, and recording the magnetic flux value of the measuring point as Fval5 when the change rate of the magnetic flux values of two adjacent times is less than one per thousand;
reversely charging the magnetic field intensity to a set magnetic field intensity-Hset for at least 200ms, and collecting the current magnetic flux value and recording the current magnetic flux value as Fval 6;
b values at Hset in the segments 0 to-Hs are calculated:
B＝Bs-(Fval5–Fval6)/(N2*Ae)
where N2 is the number of turns in the secondary coil and Ae is the cross-sectional area of the closed loop soft magnetic material.
10. A closed loop soft magnetic material dc magnetic property measuring method according to any of claims 6 to 9, characterized in that the set time interval is 100ms to 500 ms.
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