Method and mechanism for testing initial permeability of soft magnetic material

Abstract

The invention provides a method for testing the initial permeability of a soft magnetic material. The method comprises the following steps: arranging a protection box for a sample; confirming the number of turns of the magnetizing coil; confirming the number of turns of the induction coil; uniformly winding an induction coil and a magnetizing coil outside the protection box; inputting current to the magnetizing coil through test equipment, and calculating the test magnetic conductivity mu test of the test sample based on the magnetic flux of the induction coil and the sectional area S sample of the sample; and calculating the initial permeability [mu] real of the sample according to the test permeability [mu] test of the sample, the permeability [mu] box of the protection box, the sectional area S box of the protection box, the permeability [mu] gas of the air gap between the protection box and the sample, and the sectional area S gas of the air gap.

Description

Technical Field

[0001] The invention relates to the field of magnetic performance testing, and in particular to a method for testing the initial magnetic permeability of a soft magnetic material. Background Art

[0002] With the development of electronic circuit technology and detection technology, the use of fluxmeters in the process of testing the magnetic properties of soft magnetic materials is increasing, and the use of impact galvanometers to detect the magnetic properties of soft magnetic materials has begun to decrease. However, due to the limited resolution of the fluxmeters currently manufactured and the large thermal drift of the fluxmeters, it is found that the initial magnetic permeability data of the soft magnetic materials measured by the fluxmeter fluctuates greatly in the process of measuring the magnetic properties of soft magnetic materials using the fluxmeter, and the stability and repeatability of the test results are not satisfactory. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for testing the initial magnetic permeability of soft magnetic materials, thereby improving the test accuracy.

[0004] In order to achieve the above object, the present invention provides the following technical solution: a method for testing the initial magnetic permeability of a soft magnetic material, comprising the following steps: setting a protective box for the sample; confirming the number of turns of the magnetizing coil; confirming the number of turns of the induction coil; uniformly winding the induction coil and the magnetizing coil outside the protective box; inputting current into the magnetizing coil through a testing device, and determining the initial magnetic permeability of the soft magnetic material based on the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test permeability μ of the test sample 测 ; According to the test magnetic permeability μ of the sample 测 , the magnetic permeability μ of the protection box 盒 , cross-sectional area S of the protection box 盒 , the magnetic permeability μ of the air gap between the protective box and the sample 气 , the cross-sectional area S of the air gap 气 Calculate the initial magnetic permeability μ of the sample 实 .

[0005] Furthermore, the confirmation of the number of turns of the magnetizing coil includes: determining whether to test the saturation magnetic density of the sample at the same time; when the saturation magnetic density of the sample is tested at the same time, confirming that the maximum magnetizing current I output by the test equipment when testing the sample is max and the minimum magnetizing current I output by the test equipment min ; Get the maximum magnetization field strength H required for the sample test max and the specified magnetizing field strength H required for the initial magnetic permeability test of the sample min ; Obtain the magnetic path length L of the sample; According to the magnetic path length L of the sample, the maximum magnetizing field strength H max and the maximum current I maxCalculate the minimum value N1 of the number of turns of the magnetizing coil min .

[0006] Furthermore, the current input to the magnetizing coil is based on the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test magnetic permeability μ of the sample 测 The method comprises: applying a forward current to the magnetizing coil so that the magnetizing coil is at a maximum magnetizing field strength H max , obtain the magnetic flux of the induction coil by a flux meter, and according to the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the first magnetic induction intensity B of the sample at this time max Applying a negative current to the magnetizing coil causes the magnetizing coil to be in a negative direction of the maximum magnetizing field strength -H' max , obtain the magnetic flux of the induction coil through the flux meter, and according to the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the second magnetic induction intensity of the sample -B' max According to the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max , the first magnetic induction intensity B max , the second magnetic induction intensity -B' max , calculate the test magnetic permeability μ of the sample 测 .

[0007] Furthermore, in calculating the test magnetic permeability μ of the sample 测 The following steps are also included: Calculate H m The absolute value and -H' m The difference in the absolute value of max The absolute value of -B' max The absolute value difference of H m The absolute value and -H' m The absolute value difference of B max The absolute value of -B' max Whether the absolute value difference of H is less than the first preset value; m The absolute value and -H' m The absolute value difference of B max The absolute value of -B' max When the absolute value difference of the two values ​​is less than the first preset value, it is determined that the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max , the first magnetic induction intensity B max , the second magnetic induction intensity -B' max Can be used to calculate the test magnetic permeability μ of the sample测 .

[0008] Furthermore, the determination of the number of turns of the induction coil includes: obtaining the drift velocity Δφ of the fluxmeter; obtaining the time t of the hysteresis loop of the sample; and determining the estimated initial magnetic permeability μ of the sample. i ; Confirm the cross-sectional area S of the sample 样 ; According to the type of the sample to confirm the maximum magnetization field strength H required for the sample test max According to the drift of the fluxmeter Δφ, the cross-sectional area S of the sample 样 , the estimated initial magnetic permeability μ of the sample i , the maximum magnetizing field strength H measured by the hysteresis loop input when testing the initial magnetic permeability hysteresis loop max Calculate the number of turns of the induction coil.

[0009] Furthermore, the actual magnetic permeability μ of the sample is calculated 实 The formula is:

[0010] μ 实 =μ 测 -μ 盒 *S 盒 / S 样 -μ 气 *S 气 / S 样 (5).

[0011] Furthermore, the formula for calculating the minimum number of turns of the magnetizing coil is:

[0012] N 1min =H max *I max / L (6).

[0013] Furthermore, the formula for calculating the number of turns of the induction coil is:

[0014] N2≥[μ i *H min * S 样 ] / [100* t*Δφ] (7)

[0015] Wherein, N2 is the number of turns of the induction coil.

[0016] Furthermore, the calculation of the test sample test permeability μ 测 The formula is:

[0017] μ 测 =(B max +B' max ) / (H max +H' max) (8).

[0018] On the other hand, a soft magnetic material initial permeability testing mechanism is provided, comprising: a sample protection mechanism for setting a protection box for the sample; a first turns calculation mechanism for confirming the number of turns of the induction coil; a second turns calculation mechanism for confirming the number of turns of the magnetizing coil; a coil winding mechanism for evenly winding the induction coil and the magnetizing coil on the outside of the protection box; a sample detection mechanism for inputting current into the magnetizing coil through a testing device, and calculating the magnetic flux of the induction coil and the cross-sectional area S of the sample based on the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test permeability μ of the test sample 测 ; Magnetic permeability calculation mechanism, according to the test magnetic permeability μ of the sample 测 , the magnetic permeability μ of the protection box 盒 , cross-sectional area S of the protection box 盒 , the magnetic permeability μ of the air gap between the protective box and the sample 气 , the cross-sectional area S of the air gap 气 Calculate the initial magnetic permeability μ of the sample 实 .

[0019] Analysis shows that the present invention discloses a method and mechanism for testing the initial magnetic permeability of soft magnetic materials. The present invention can overcome the many shortcomings of large fluctuations in the initial magnetic permeability data of soft magnetic materials, instability of test results, and poor repeatability when using a fluxmeter to measure the magnetic permeability of soft magnetic materials. A protective box is prepared using a weakly magnetic material, which has specific dimensions and weak magnetic properties and a constant magnetic permeability. The number of turns of the magnetizing coil and induction coil required to be wound around the test sample ring is calculated based on the capabilities of the testing equipment used, the approximate magnetic properties of the material being tested, the ability of the testing equipment to control the magnetizing field strength, and the accuracy of the flux integrator, thereby reducing the workload caused by repeated winding. The principle of calculating the magnetic properties of the material during impact measurement is utilized, and the hysteresis loop data points of the soft magnetic material are obtained by measuring the magnetic material under low field strength, and finally the initial magnetic permeability of the high magnetic permeability material is calculated. This reduces the influence of the soft magnetic material demagnetization on the test results, and the test results are characterized by high accuracy and good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. Among them:

[0021] Figure 1 Flowchart of an embodiment of the present invention.

[0022] Figure 2 Flowchart of an embodiment of the present invention.

[0023] Figure 3A schematic diagram of the structure of a sample during testing according to an embodiment of the present invention.

[0024] Explanation of the accompanying drawings: 1. Sample; 2. Protective box; 3. Magnetizing coil. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. Each example is provided by way of explanation of the present invention and is not intended to limit the present invention. Indeed, it will be apparent to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention encompasses such modifications and variations as come within the scope of the appended claims and their equivalents.

[0026] One or more examples of the present invention are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and the description have been used to refer to like or similar parts of the present invention. As used herein, the terms "first," "second," "third," and "fourth," etc. are used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of individual components.

[0027] like Figure 1 As shown, according to an embodiment of the present invention, a method for testing the initial magnetic permeability of a soft magnetic material is provided, comprising the following steps:

[0028] Step S101: setting a protection box for the sample.

[0029] like Figure 2 As shown, the sample of the present invention is an annular sample. A ring-shaped protective box with a U-shaped cross section is used for the annular sample. When the sample is placed in the protective box, the height of the protective box is usually slightly higher than the sample to ensure that the sample to be tested is not subjected to external force when the induction coil and the magnetization coil are wound.

[0030] Typically, the protective box is sized to fit the sample snugly within its slot. For example, if the sample has an outer diameter of 40mm, an inner diameter of 32mm, and a thickness of 5-7mm, the inner ring dimensions of the sample protective box should be approximately 40.2mm in outer diameter, 31.8mm in inner diameter, and 6-8mm in depth. The box's wall thickness ensures that the pressure from winding the wire prevents the box from deforming and squeezing the sample. The sample box is made of paramagnetic material with a relative magnetic permeability of approximately 1, typically ranging from 0.95 to 1.05.

[0031] The relative magnetic permeability of the material used to prepare the above-mentioned protective box is usually 0.95 to 1.05, and its magnetic permeability remains constant during the entire test process.

[0032] The protective box is made of paramagnetic or other weakly magnetic materials to ensure that the soft magnetic material is not affected by stress in the protective box after the magnetizing coil and the induction coil are wound around the protective box.

[0033] Step S102: confirm the number of turns of the magnetizing coil.

[0034] The above-mentioned confirmation of the number of turns of the magnetizing coil includes the following steps:

[0035] Step S1021, determine whether to test the saturation magnetic density of the sample at the same time; when the saturation magnetic density of the sample is tested at the same time, confirm the maximum magnetizing current I output by the test equipment when testing the sample. max and the minimum magnetizing current I output by the test equipment min ;

[0036] Step S1022: Obtain the maximum magnetization field strength H required for sample testing. max And the specified magnetizing field strength H required for the sample initial permeability test min , the specified magnetizing field strength H min The specified magnetizing field strength required to test the initial magnetic permeability;

[0037] Step S1023, obtaining the magnetic path length L of the sample;

[0038] Step S1024: Based on the magnetic path length L and the maximum magnetizing field strength H of the sample max and the maximum current I max Calculate the minimum number of turns of the magnetizing coil N1 min , the minimum number of turns of the magnetizing coil is N1 min In order to test other parameters of soft magnetic materials such as the minimum number of turns required for saturation flux density, the number of turns of the magnetizing coil is higher than the minimum value N1 when used. min That is, when testing the initial magnetic permeability, in order to improve the control accuracy of the magnetizing field strength during the measurement process, an additional magnetizing coil can be wound, and the number of turns of the magnetizing coil is 1. At this time, the test equipment has the highest control accuracy of the magnetizing field strength during the magnetization process, but the uniformity of the magnetizing field strength of the single-turn coil is limited; in actual application, the number of turns of the magnetizing coil is appropriately increased according to the minimum output current and the resolution of the output current of the equipment. Usually, the magnetizing coil with multiple turns will be evenly wound outside the annular sample box, and at the same time, it is ensured that the magnetizing field strength generated in the magnetizing coil by the output current of the test equipment when testing the initial magnetic permeability is stable and controllable throughout the test process.

[0039] The above formula for calculating the minimum number of turns of the magnetizing coil at the maximum magnetizing field strength is:

[0040] N 1min =H max * I max / L (9)

[0041] Step S103: confirm the number of turns of the induction coil.

[0042] Confirming the number of turns of the induction coil specifically includes the following steps: obtaining the drift velocity Δφ of the fluxmeter; obtaining the time t of the hysteresis loop of the sample; confirming the estimated initial magnetic permeability μ of the sample i , usually the estimated magnetic permeability of the sample is determined by the material of the sample; confirm the cross-sectional area S of the sample 样 ; Determine the maximum magnetic field strength H required for sample testing based on the material type of the sample max , the maximum magnetizing field strength H max It is the magnetizing field strength set according to the type of material when testing the initial magnetic permeability of the sample; according to the drift speed Δφ of the fluxmeter and the cross-sectional area S of the sample 样 , the estimated initial magnetic permeability μ of the sample i , maximum magnetizing field strength H max Calculate the number of turns N2 of the induction coil

[0043] When using the simulated impact method to test the initial permeability of high-permeability materials, the time t for the combined hysteresis loop of the sample and protective box is typically kept between 5 and 60 seconds. This time can be adjusted based on actual conditions. This ensures that the short test time does not generate eddy currents in the sample, potentially affecting the accuracy of the test results. This ensures that the fluxmeter drift is less than t*Δφ throughout the test. To minimize the effect of fluxmeter drift on the measured data to less than 1%, the flux change sensed by the fluxmeter during the test must be greater than or equal to 100*t*Δφ.

[0044] The above formula for calculating the number of turns of the induction coil is:

[0045] N2≥[μ i *H min * S 样 ] / [100* t*Δφ] (10)

[0046] Where N2 is the number of turns of the induction coil.

[0047] Step S104: Evenly wind the induction coil and the magnetization coil around the outside of the protection box.

[0048] The induction coil and magnetization coil with confirmed number of turns are wound around the outside of the protection box to prepare for subsequent testing.

[0049] Specifically, the induction coil is usually evenly wound around the protective box first, and then the magnetizing coil is wound above the induction coil. This method can more accurately calculate the air gap size. Even if the induction coil and the magnetizing coil overlap, the actual effect can be ignored.

[0050] Step S105: input current to the magnetizing coil through the testing equipment, and based on the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the test permeability μ of the test sample 测 , the test equipment measures the overall magnetic flux of the sample to be tested, the protection box and the air gap.

[0051] The above input current to the magnetizing coil is based on the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test magnetic permeability μ of the sample 测 Including: applying a positive current to the magnetizing coil to make the magnetizing coil at the maximum magnetizing field strength H max , obtain the magnetic flux of the induction coil through the flux meter, and according to the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the first magnetic induction intensity B of the sample at this time max ; Apply negative current to the magnetizing coil to make the magnetizing coil in the negative maximum magnetizing field strength -H' max , obtain the magnetic flux of the induction coil through the flux meter, and according to the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the second magnetic induction intensity of the sample -B' max ; According to the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max , the first magnetic induction intensity B max , the second magnetic induction intensity -B' max , calculate the test magnetic permeability μ of the sample 测 .

[0052] The first overall magnetic induction intensity B of the test sample and the protective box is obtained by the flux meter. max and the second overall magnetic induction intensity -B' max Specifically: Since the fluxmeter measures the magnetic flux of the induction coil φ 测 The magnetic induction intensity B of the sample is measured 测 There is: φ 测 =N2*B 测 *S 样 The relationship between the test magnetic induction intensity B 测 Without removing the effect of the air gap of the protective box on the magnetic flux, the first overall magnetic induction intensity B max and the second overall magnetic induction intensity -B' max All based on sample test magnetic induction intensity B 测 The calculation formula is calculated.

[0053] Specifically, during the test, the input current to the magnetizing coil is usually increased slowly, and the input current is not greater than I max , slowly increase the positive current applied to the magnetizing coil to make the maximum magnetizing field strength H of the magnetizing coilmax The magnetization field strength point is approximately equal to the initial magnetic permeability required by the sample to be tested. At this time, the first magnetic induction intensity B can be measured by the hysteresis loop measuring equipment or fluxmeter max ; Then slowly reduce the magnetizing current in the magnetizing coil until it is reversed and then increase until the maximum negative magnetizing field strength -H' max Value, -H' max The value is also approximately equal to the magnetization field strength point of the initial magnetic permeability of the sample to be tested as required by the national standard. The second magnetic induction intensity -B' in the opposite direction of the test sample and the protective box can also be measured by the hysteresis loop measuring equipment or fluxmeter. max ; According to the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max , the first magnetic induction intensity B max , the second magnetic induction intensity -B' max , calculate the test permeability μ of the test sample 测 .

[0054] Usually, the following steps are included before calculating the test magnetic permeability of the test sample: 测 The following steps are also included: Calculate H m The absolute value and -H' m The difference in the absolute value of max The absolute value of -B' max The absolute value difference of H m The absolute value and -H' m The absolute value difference of B max The absolute value of -B' max Is the absolute value difference of the two values ​​less than the first preset value? If it is less than the preset value, it means that the sample is well demagnetized (except for anisotropic materials). m The absolute value and -H' m The absolute value difference of B max The absolute value of -B' max When the absolute value difference of the two values ​​is less than the first preset value, it is determined that the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max , the first magnetic induction intensity B max , the second magnetic induction intensity -B' max Can be used to calculate the test magnetic permeability μ of the sample 测 .

[0055] The first preset value mentioned above is usually 2%.

[0056] Since demagnetization is performed reasonably according to different materials during testing, whether the demagnetization is completely effective can be judged by whether the measured hysteresis loop is symmetrical up and down.max with -H max B max with -B' max If they are basically equal, it can be determined that the tested sample has basically completed the demagnetization before the test. According to the test experience, there is always a certain error in the test. Usually B max with -B' max An absolute value difference of ≤ 2% is acceptable.

[0057] The hysteresis loop is tested according to the standard or the initial permeability requirements of various materials, and the permeability is calculated using the final measured hysteresis loop, so the test permeability μ of the test sample is calculated. 测 The formula is:

[0058] μ 测 =(B max +B' max ) / (H max +H' max ) (11)

[0059] This calculation method is not limited to calculating the initial magnetic permeability, but can also be used to calculate the magnetic permeability data of any soft magnetic material at any test point.

[0060] The hysteresis loop of the DC magnetic properties of soft magnetic alloys tested by flux meter integration method is as follows Figure 3 As shown, from Figure 3 It can be seen that the fluxmeter integration method can record the magnetic flux of the sample passing through the induction coil during the entire magnetization process. Therefore, the data tested by the fluxmeter integration method can be used to calculate all the magnetic permeability values ​​of the magnetic material during the entire magnetization process. In order to better conform to the testing principle of the impact method, we also use the point-to-point magnetization method to take points when calculating the magnetic permeability, and take the maximum magnetic field strength point (+H max , B max ) and the maximum magnetization field strength point in the third quadrant (-H' max , -B' max ) The magnetization field strength and induction field strength corresponding to the two points are used as the basis for calculation (generally, these two points are symmetrical about the origin, H max ≈H' max , B≈B', but at ultra-low magnetizing field strengths, the values ​​of the two points obtained may differ due to the limited control of the equipment on the precision of the magnetizing current. This method can basically ignore the influence of incomplete demagnetization of soft magnetic materials, which can greatly improve the accuracy and reproducibility of test results.

[0061] Step S106: According to the test magnetic permeability μ of the sample 测 , magnetic permeability of the protection box μ 盒, cross-sectional area S of the protection box 盒 , the magnetic permeability μ of the air gap between the protective box and the sample 气 , cross-sectional area of ​​the air gap S 气 Calculate the initial magnetic permeability μ of the sample 实 .

[0062] The actual magnetic permeability μ of the sample calculated above is 实 The formula is:

[0063] μ 实 =μ 测 -μ 盒 *S 盒 / S 样 -μ 气 *S 气 / S 样 (12).

[0064] When μ 盒 ≈μ 气 ≈μ0, μ 实 =μ 测 -μ0*(S 盒 +S 气 ) / S 样 , where μ0 is the magnetic permeability of vacuum.

[0065] The present invention also discloses a testing mechanism for the initial magnetic permeability of soft magnetic materials, comprising: a sample protection mechanism for setting a protection box for the sample; a first turns calculation mechanism for confirming the turns of the induction coil; a second turns calculation mechanism for confirming the turns of the magnetizing coil; a coil winding mechanism for evenly winding the induction coil and the magnetizing coil on the outside of the protection box; a sample detection mechanism for inputting current to the magnetizing coil through a testing device, and calculating the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test permeability μ of the test sample 测 ; Magnetic permeability calculation mechanism, based on the test magnetic permeability μ of the sample 测 , magnetic permeability of the protection box μ 盒 , cross-sectional area S of the protection box 盒 , the magnetic permeability μ of the air gap between the protective box and the sample 气 , cross-sectional area of ​​the air gap S 气 Calculate the initial magnetic permeability μ of the sample 实 .

[0066] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the present invention can overcome the many shortcomings of large fluctuations in the initial magnetic permeability data of soft magnetic materials, instability of test results and poor repeatability in the process of measuring the magnetic permeability of soft magnetic materials using a fluxmeter. The protective box is made of weakly magnetic materials, which has specific dimensions and weak magnetic properties and constant magnetic permeability. The number of turns of the magnetizing coil and the induction coil required to be wound around the test sample ring is calculated based on the capabilities of the testing equipment used, the approximate magnetic properties of the material being tested, the control ability of the testing equipment on the magnetizing field strength, and the accuracy of the flux integrator, so as to reduce the workload caused by repeated winding. The principle of calculating the magnetic properties of the material during the impact method measurement is utilized, and the hysteresis loop data points of the soft magnetic material are obtained by measuring the magnetic material under low field strength to finally calculate the initial magnetic permeability of the high magnetic permeability material. Thus, the test results are less affected by the demagnetization of the soft magnetic material, and the test results are highly accurate and repeatable.

[0067] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for testing the initial magnetic permeability of a soft magnetic material, characterized in that: The following steps are involved: Set up a protective box for the sample; Confirm the number of turns of the magnetizing coil; Confirm the number of turns of the induction coil; Evenly winding the induction coil and the magnetization coil on the outside of the protection box; The test equipment inputs current into the magnetizing coil, and based on the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the test magnetic permeability μ of the test sample 测 ; According to the test magnetic permeability μ of the sample 测 , the magnetic permeability μ of the protection box 盒 , the cross-sectional area of ​​the protection box S 盒 , the magnetic permeability μ of the air gap between the protection box and the sample 气 , the cross-sectional area S of the air gap 气 Calculate the initial magnetic permeability μ of the sample 实 .

2. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 1, characterized in that: The confirmation of the number of turns of the magnetizing coil comprises: Determine whether to test the saturation magnetic density of the sample at the same time; when the saturation magnetic density of the sample is tested at the same time, confirm that the maximum magnetizing current I output by the test device when testing the sample max and the minimum magnetizing current I output by the test equipment min ; Get the maximum magnetization field strength H required for the sample test max and the specified magnetizing field strength H required for the initial magnetic permeability test of the sample min ; Obtaining the magnetic path length L of the sample; According to the magnetic path length L of the sample, the maximum magnetization field strength H max and the maximum current I max Calculate the minimum number of turns of the magnetizing coil N1 min .

3. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 2, characterized in that: The input current to the magnetizing coil is based on the magnetic flux of the induction coil and the cross-sectional area S of the sample. 样 Calculate the test magnetic permeability μ of the sample 测 include: A positive current is applied to the magnetizing coil to make the magnetizing coil at the maximum magnetizing field strength H max , obtain the magnetic flux of the induction coil by a flux meter, and calculate the magnetic flux of the induction coil and the cross-sectional area S of the sample according to the magnetic flux of the induction coil 样 Calculate the first magnetic induction intensity B of the sample at this time max ; A negative current is applied to the magnetizing coil to make the magnetizing coil in a negative maximum magnetizing field strength -H' max , the magnetic flux of the induction coil is obtained by the flux meter, and according to the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the second magnetic induction intensity of the sample -B' max ; According to the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max 、The first magnetic induction intensity B max , the second magnetic induction intensity -B' max , calculate the test magnetic permeability μ of the sample 测 .

4. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 3, characterized in that: In the calculation of the test magnetic permeability μ of the sample 测 The previous steps also include: Calculate H m The absolute value and -H' m The absolute value difference of Calculate B max The absolute value and -B' max The absolute value difference of Judge H m The absolute value and -H' m The absolute value difference of B max The absolute value and -B' max Whether the absolute value differences of are all less than a first preset value; When H m The absolute value and -H' m The absolute value difference of B max The absolute value and -B' max When the absolute value difference of is less than the first preset value, it is determined that the maximum magnetization field strength H max , the maximum negative magnetizing field strength -H' max 、The first magnetic induction intensity B max , the second magnetic induction intensity -B' max Can be used to calculate the test magnetic permeability μ of the sample 测 .

5. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 3, characterized in that: The confirmation of the number of turns of the induction coil comprises: Obtaining a drift velocity Δφ of the fluxmeter; Obtaining the time t of the hysteresis loop of the sample for testing; Confirm the estimated initial magnetic permeability μ of the sample i ; Confirm the cross-sectional area S of the sample 样 ; Determine the maximum magnetization field strength H required for the sample test according to the type of the sample max ; According to the drift Δφ of the fluxmeter and the cross-sectional area S of the sample 样 , the estimated initial magnetic permeability μ of the sample i , the maximum magnetizing field strength H measured by the hysteresis loop input when testing the initial permeability hysteresis loop max Calculate the number of turns of the induction coil.

6. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 2, characterized in that: The actual magnetic permeability μ of the sample is calculated 实 The formula is: m 实 =μ 测 -m 盒 *S 盒 / S 样 -m 气* S 气 / S 样 (1)。 7. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 2, characterized in that: The formula for calculating the minimum number of turns of the magnetizing coil is: N 1min =H max * I max / L (2)。 8. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 5, characterized in that: The formula for calculating the number of turns of the induction coil is: N2≥[μ i *H min * S 样 ] / [100* t*Δφ] (3) Wherein, N2 is the number of turns of the induction coil.

9. A method for testing the initial magnetic permeability of a soft magnetic material according to claim 4, characterized in that: The calculation of the test sample test permeability μ 测 The formula is: μ 测 =(B max +B' max ) / (H max +H' max ) (4)。 10. A soft magnetic material initial magnetic permeability testing mechanism, characterized in that: include: A sample protection mechanism, which provides a protection box for the sample; A first turns calculation mechanism, for determining the turns of the induction coil; A second turns calculation mechanism, for confirming the turns of the magnetizing coil; A coil winding mechanism, which evenly winds the induction coil and the magnetization coil around the outside of the protection box; The sample detection mechanism inputs current into the magnetizing coil through the testing equipment, and based on the magnetic flux of the induction coil and the cross-sectional area S of the sample 样 Calculate the test magnetic permeability μ of the test sample 测 ; Magnetic permeability calculation mechanism, based on the test magnetic permeability μ of the sample 测 , the magnetic permeability μ of the protection box 盒 , the cross-sectional area of ​​the protection box S 盒 , the magnetic permeability μ of the air gap between the protection box and the sample 气 , the cross-sectional area S of the air gap 气 Calculate the initial magnetic permeability μ of the sample 实 .

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