A method for screening magnetic cores based on complex magnetic permeability

Abstract

The present invention discloses a method for screening magnetic cores based on complex magnetic permeability, comprising the following steps: S1, placing a single-turn closed-loop magnetic core on a test stand; S2, inserting two test clips of a data acquisition device into the magnetic core through both ends of the magnetic core and clamping them together so that the clamped test clips remain in the magnetic core; collecting the series inductance Ls and quality factor Q of the magnetic core by the data acquisition device, and recording them as character string information; S3, communicating with the data acquisition device, writing the character string information of step S2 into the data processing device, and converting the character string information into numerical information after the data processing device reads the character string information; S4, the data processing device reads the numerical information of step S3 to obtain the series real part μs' and the series imaginary part μs" of the complex magnetic permeability of the magnetic core; and S6, based on a set complex magnetic permeability range, screening out magnetic cores whose complex magnetic permeabilities calculated in steps S4 and S5 are within the complex magnetic permeability range.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic core screening methods, and in particular to a method for screening magnetic cores based on complex magnetic permeability. Background Art

[0002] The complex permeability of the magnetic core is a key technical indicator. In practical applications, in order to better achieve product performance, it is necessary to screen out magnetic cores with complex permeabilities that meet a certain range. Therefore, it is necessary to first obtain the complex permeability of the magnetic core.

[0003] The complex magnetic permeability μ is divided into the real part μ' and the imaginary part μ", and due to the different circuit forms, it is further divided into series and parallel. Specifically, the series real part is: μs', the series imaginary part is: μs", the parallel real part is: μp', and the parallel imaginary part is: μp".

[0004] The current method for obtaining complex permeability is relatively complex, requiring the testing of multiple sets of data such as inductance, impedance, and frequency. The calculations are relatively complex and the test speed is slow. On the other hand, there are currently few instruments available on the market for testing the complex permeability of magnetic cores. Most use a measurement-and-calculation method, as instruments capable of measuring permeability are expensive and cannot meet the requirements of rapid production testing, and are only used for experimental purposes. The 6500B series analyzers produced by the UK-based Wenco can measure complex permeability, with a measurement frequency of 5M-120MHz. However, they cost 150,000-350,000 RMB. Since the frequency of magnetic cores is mostly below 200KHz, using the Wenco 6500B would be a waste, and most companies cannot afford the high cost.

[0005] An LCR meter can measure inductance, capacitance, and impedance. However, when applying an LCR meter to acquire data on the complex permeability of a magnetic core, the problem of transferring the instrument's measured values ​​to a computer for computational purposes arises. This is because the instrument manufacturer does not provide acquisition program code, but the instrument does provide a data interface. Therefore, if you want to perform secondary computations and utilize the instrument's test values ​​to transfer them to a computer via the data interface, you need to write a dedicated acquisition program. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for screening magnetic cores based on complex magnetic permeability in order to overcome the shortcomings of the existing technology, provide a solution for quickly screening out magnetic cores that meet the requirements, solve the problems of complicated screening steps, slow data acquisition speed, high data acquisition cost and data collection in secondary development operations in the existing technology, avoid various shortcomings of manual data input, and at the same time, there is no need to purchase new equipment, saving costs.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for screening magnetic cores based on complex magnetic permeability comprises the following steps:

[0009] S1. Place the single-turn closed-loop magnetic core on the test stand;

[0010] S2. Insert two test clips of a data acquisition device into the magnetic core through both ends of the magnetic core and clamp them together so that the clamped test clips remain in the magnetic core; collect the series inductance Ls and quality factor Q of the magnetic core using the data acquisition device and record them as a string of information;

[0011] S3, connecting the data processing device to the data acquisition device, writing the character string information of step S2 into the data processing device, and converting the character string information into numerical information after the data processing device reads the character string information;

[0012] S4. The data processing device reads the numerical information of step S3 and obtains the series real part μs' and the series imaginary part μs" of the complex permeability of the magnetic core based on calculation formula A. Calculation formula A is as follows:

[0013]

[0014]

[0015] Where μs' and μs" are the series real and series imaginary parts of the complex permeability, Ls is the series inductance of the core, Le is the equivalent length of the core's magnetic path, Ae is the equivalent cross-sectional area of ​​the core, Q is the quality factor of the core, and π is the circumference of the magnetic core.

[0016] S5. Based on the series real part μs' and the series imaginary part μs", of the series complex permeability obtained in step S4, the parallel real part μP' and the parallel imaginary part μP" of the complex permeability of the magnetic core are obtained based on calculation formula B. The calculation formula B is as follows:

[0017]

[0018]

[0019] Wherein, μs' and μs" are the series real part and series imaginary part of the complex permeability, μP' and μP" are the parallel real part and parallel imaginary part of the complex permeability, and Q is the quality factor of the magnetic core;

[0020] S6. Based on the set numerical ranges of the series real part μs', the series imaginary part μs", the parallel real part μP' and the parallel imaginary part μP", the magnetic cores whose series real part μs', the series imaginary part μs", the parallel real part μP' and the parallel imaginary part μP" calculated in steps S4 and S5 are within the set ranges are screened out.

[0021] The present invention converts the character string information of the data acquisition device into numerical information through a data processing device, and then performs secondary development calculations on the numerical information. At the same time, combined with a calculation formula, it is only necessary to obtain the numerical information of the inductance Ls and the numerical information of the quality factor Q to obtain the complex magnetic permeability of the magnetic core, thereby quickly screening out magnetic cores that meet the requirements and whose complex magnetic permeability is within a specified range.

[0022] Furthermore, the data processing device is provided with a data acquisition program for converting character string information into numerical information.

[0023] Furthermore, the data acquisition program includes the following steps: the communication port, baud rate, and bit rate settings of the data acquisition program work interface are consistent with the communication port, baud rate, and bit rate settings of the data acquisition device, so that the data processing device is communicatively connected with the data acquisition device.

[0024] Furthermore, step S3 includes:

[0025] S31, after writing the character string information of the data acquisition device into the data acquisition program, the data acquisition program reads the character string information;

[0026] S32: The data acquisition program splits the string information into two segments of string information. A separator is provided between the two segments of string information for separation. The string information before the separator is the string information of the series inductance Ls, and the string information after the separator is the string information of the quality factor Q.

[0027] S33, converting the string information of the series inductor Ls in step S32 into the numerical information of the series inductor Ls; converting the string information of the quality factor Q in step S32 into the numerical information of the quality factor Q;

[0028] S34. Display the numerical information obtained in step S33 through a display control.

[0029] Furthermore, the step S31 is further configured to set a total amount of character string information, and the reading is stopped after the total amount of character string information is read.

[0030] Furthermore, in step S32, a first string length X1 and a second string length X2 are set. The length of the string information is separated into string information of two lengths by the delimiter. The length of the string information before the delimiter is the first string length X1, and the length of the string information after the delimiter is the second string length X2. The string information of the first string length X1 before the delimiter is first read and recorded as the string information of the series inductance Ls, and then the string information of the second string length X2 after the delimiter is read and recorded as the string information of the quality factor Q.

[0031] Furthermore, a verification method for the first character string length X1 and the second character string length X2 is also included. The verification method includes: first setting a first preset character string length X1 and a second preset character string length X2. 10 and the second preset string length X 20 , by first presetting the string length X 10 and the second preset string length X 20 The character string information is split to obtain two segments of character string information, the character string information before the separator is set as the first character string information, and the character string information after the separator is set as the second character string information, and the first character string information and the second character string information are converted into first numerical information and second numerical information respectively, and then it is determined whether the first numerical information and the second numerical information are equal to the numerical value of the series inductance Ls and the numerical value of the quality factor Q displayed on the data acquisition device. If the determination is yes, the first preset character string length X is set. 10 That is, the first character string length X1, the second preset character string length X 20 That is, the second character string length X2. If the judgment is no, the first preset character string length X is modified. 10 The length value and the second preset string length X 20 Length value, check again.

[0032] Furthermore, in step S33, the character string information having a length equal to the first character string length X1 is converted into numerical information, i.e., numerical information of the series inductance Ls is obtained; and the character string information having a length equal to the second character string length X2 is converted into numerical information, i.e., numerical information of the quality factor Q is obtained.

[0033] Furthermore, in order to reduce the test cost of the present invention, the data acquisition device is an LCR meter. The LCR digital bridge includes a data interface, such as RS232, RS485, GPIB interface, USB interface, etc.

[0034] Beneficial effects of the present invention:

[0035] 1. The present invention converts the character string information of the data acquisition device into numerical information through a data processing device, and then performs secondary development calculations on the numerical information. At the same time, combined with the calculation formula, it is only necessary to obtain the numerical information of the inductance Ls and the numerical information of the quality factor Q to obtain the complex magnetic permeability of the magnetic core, thereby quickly screening out magnetic cores that meet the requirements and whose complex magnetic permeability is within the specified range.

[0036] 2. Through the data acquisition program, the test values ​​of the data acquisition device are collected into the computer through the data interface for secondary development and operation, solving the problem of collecting the measurement values ​​of the data acquisition device into the computer for program operation. The data acquisition program runs stably and quickly.

[0037] 3. The present invention adopts an LCR tester as a data acquisition device, thereby reducing the testing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a program working interface in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the second program working interface in an embodiment of the present invention;

[0040] Figure 3 Schematic diagram of the third program working interface in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the technical solutions, objectives and advantages of the present invention more clearly understood, the present invention is further explained below with reference to the accompanying drawings and embodiments.

[0042] A method for screening magnetic cores based on complex magnetic permeability comprises the following steps:

[0043] S1. Place the single-turn closed-loop magnetic core on the test stand;

[0044] S2. Insert two test clips of a data acquisition device into the magnetic core through both ends of the magnetic core and clamp them together so that the clamped test clips remain in the magnetic core; collect the series inductance Ls and quality factor Q of the magnetic core using the data acquisition device and record them as a string of information;

[0045] In this embodiment, the data acquisition device is an LCR meter, specifically a TH2816A bridge, with its communication port being COM3, the baud rate set to 9600, and the data bit set to 8. After the TH2816A bridge is calibrated and debugged, the test item is set to the Ls-Q test page, and the TH2816A bridge is cleared for open and short circuits.

[0046] S3. The data processing device is connected to the data acquisition device. Specifically, the data processing device is provided with a data acquisition program for converting character string information into numerical information. Before the test begins, the power of the LCR meter is turned on, the computer is turned on, and the program interface of the data acquisition program set in the data processing device is opened, such as Figure 1 As shown, select the "Data Acquisition" page, select the communication port as COM3, set the baud rate to 9600, and the data bit to 8. The above technical parameters are consistent with the technical parameter settings of the LCR tester. Use the transmission line to connect the data acquisition device and the data processing device for serial communication to achieve communication between the serial port of the data acquisition device and the data processing device.

[0047] Then, the character string information of step S2 is written into a data processing device, which reads the character string information and converts it into numerical information. Specifically, the steps include:

[0048] S31. After the string information of the data acquisition device is written into the data acquisition program, the data acquisition program reads the string information. To prevent the data acquisition program from repeatedly writing string information, this step also sets a total amount of string information. After reading the total amount of string information, the program stops reading. This can further improve the running speed and avoid freezes.

[0049] S32: The data acquisition program splits the string information into two segments, with a delimiter separating the two segments. The string information before the delimiter is the string information of the series inductor Ls, and the string information after the delimiter is the string information of the quality factor Q. Specifically, a first string length X1 and a second string length X2 are set. The delimiter is used to separate the string information into two lengths: the length of the string information before the delimiter is the first string length X1, and the length of the string information after the delimiter is the second string length X2. The string information of the first string length X1 before the delimiter is first read and recorded as the string information of the series inductor Ls. The string information of the second string length X2 after the delimiter is then read and recorded as the string information of the quality factor Q.

[0050] Before testing, the first character string length X1 and the second character string length X2 need to be verified. The verification method includes: first setting the first preset character string length X1 and the second character string length X2. 10 and the second preset string length X 20 , by first presetting the string length X 10 and the second preset string length X 20The character string information is split to obtain two segments of character string information, the character string information before the separator is set as the first character string information, and the character string information after the separator is set as the second character string information, and the first character string information and the second character string information are converted into first numerical information and second numerical information respectively, and then it is determined whether the first numerical information and the second numerical information are equal to the numerical value of the series inductance Ls and the numerical value of the quality factor Q displayed on the data acquisition device. If the determination is yes, the first preset character string length X is set. 10 That is, the first character string length X1, the second preset character string length X 20 That is, the second character string length X2. If the judgment is no, the first preset character string length X is modified. 10 The length value and the second preset string length X 20 Length value, check again.

[0051] S33. Convert the string information of the series inductor Ls in step S32 into numerical information of the series inductor Ls. Convert the string information of the quality factor Q in step S32 into numerical information of the quality factor Q. Specifically, convert the string information having a length of the first string length X1 into numerical information to obtain numerical information of the series inductor Ls. Convert the string information having a length of the second string length X2 into numerical information to obtain numerical information of the quality factor Q.

[0052] S34. Display the numerical information obtained in step S33 through a display control.

[0053] Step S3 is as follows: Figure 2 As shown, select the "Parameter Input" page in the working interface, enter the equivalent cross-sectional area Ae of the core and the equivalent length Le of the core magnetic circuit; obtain the numerical information of the series inductance Ls and the quality factor Q of the core.

[0054] S4. The data processing device reads the numerical information of step S3 and obtains the series real part μs' and the series imaginary part μs" of the complex permeability of the magnetic core based on calculation formula A. The calculation formula A is as follows:

[0055]

[0056]

[0057] Wherein, μ' and μ" are the series real part and the series imaginary part of the complex permeability, respectively, Ls is the series inductance of the magnetic core, Le is the equivalent length of the magnetic path of the magnetic core, Ae is the equivalent cross-sectional area of ​​the magnetic core, Q is the quality factor of the magnetic core, and π is pi.

[0058] S5. Based on the series real part μs' and the series imaginary part μs", of the series complex permeability obtained in step S4, the parallel real part μP' and the parallel imaginary part μP" of the complex permeability of the magnetic core are obtained based on the calculation formula B. The calculation formula B is as follows:

[0059]

[0060]

[0061] Wherein, μs' and μs" are the series real part and series imaginary part of the complex permeability, μP' and μP" are the parallel real part and parallel imaginary part of the complex permeability, and Q is the quality factor of the magnetic core.

[0062] The series real part, series imaginary part, parallel real part and parallel imaginary part of the complex permeability are obtained by the calculation of the above formula, and are displayed on the "Permeability Test" page in the working interface. The data of the series real part, series imaginary part, parallel real part and parallel imaginary part can be read. At this point, the test is completed and click "Stop Test". Figure 3 shown.

[0063] S6. Based on the set numerical ranges of the series real part μs', the series imaginary part μs", the parallel real part μP' and the parallel imaginary part μP", the magnetic cores whose series real part μs', the series imaginary part μs", the parallel real part μP' and the parallel imaginary part μP" calculated in steps S4 and S5 are within the set ranges are screened out.

[0064] Following the above steps, due to production process or product design requirements, it is necessary to select a core with a complex permeability range at different frequencies as shown in the following table:

[0065]

[0066]

[0067] Samples 1, 2, 3, 4, and 5 were selected for screening based on complex permeability. All of the samples 1, 2, 3, 4, and 5 are single-turn toroidal cores with dimensions of 28 cm*19 cm*10 cm. The equivalent cross-sectional area Ae and the equivalent magnetic circuit length Le of each sample are shown in the following table:

[0068] Group Equivalent cross-sectional area Ae(cm^2) Equivalent length of magnetic circuit Le(cm) Sample 1 0.36 7.38 Sample 2 0.36 7.38 Sample 3 0.36 7.38 Sample 4 0.36 7.38 Sample 5 0.36 7.38

[0069] The complex permeability of Samples 1, 2, 3, 4 and 5 was tested at different frequencies according to the calculation formulas A and B, and the results are shown in the following table:

[0070]

[0071] The above results demonstrate that the screening method of this embodiment acquires complex permeability numerical information for each sample in only 0.5 seconds. Based on this complex permeability numerical information, magnetic cores falling within a predetermined complex permeability range are screened. The present invention converts string information from a data acquisition device into numerical information via a data processing device, then performs secondary development operations on the numerical information. Simultaneously, combined with a calculation formula, the complex permeability of the magnetic core can be determined by simply acquiring the numerical information of the inductance Ls and the quality factor Q, thereby rapidly screening out magnetic cores that meet the requirements and whose complex permeabilities are within the specified range.

[0072] The above description is only a preferred embodiment of the present invention. Those skilled in the art can still modify the embodiment without departing from the implementation principle of the present invention, and the corresponding modifications should also be considered as the scope of protection of the present invention.

Claims

1. A method for screening magnetic cores based on complex magnetic permeability, characterized in that: The following steps are included: S1. Place the single-turn closed-loop magnetic core on the test stand; S2. Insert two test clips of a data acquisition device into the magnetic core through both ends of the magnetic core and clamp them together so that the clamped test clips remain in the magnetic core; collect the series inductance Ls and quality factor Q of the magnetic core using the data acquisition device and record them as a string of information; S3, connecting the data processing device to the data acquisition device, writing the character string information of step S2 to the data processing device, and converting the character string information into numerical information after the data processing device reads the character string information; S4, the data processing device reads the numerical information of step S3, and obtains the series real part μs of the complex permeability of the magnetic core based on the calculation formula A ′ And the series imaginary part μs", the calculation formula A is as follows: Where, μs ′ and μs" are the series real part and series imaginary part of the complex permeability, respectively, Ls is the series inductance of the core, Le is the equivalent length of the magnetic path of the core, Ae is the equivalent cross-sectional area of ​​the core, Q is the quality factor of the core, and π is the circumference of the circle; S5, the series real part μs of the series complex permeability obtained according to step S4 ′ and the series imaginary part μs", the parallel real part μp of the parallel complex permeability of the magnetic core is obtained based on the calculation formula B ′ And the parallel imaginary part μp", the calculation formula B is as follows: Where, μs ′ and μs" are the series real and series imaginary parts of the complex permeability, μp ' and μp" are the parallel real and parallel imaginary parts of the complex permeability, respectively, and Q is the quality factor of the core; S6, based on the set series real part μs ′ , series imaginary part μs", parallel real part μp ' and the numerical range of the parallel imaginary part μp", the series real part μs calculated in steps S4 and S5 ′ , series imaginary part μs", parallel real part μp ' The cores with the parallel imaginary part μp" within the set range are screened out.

2. The method for screening magnetic cores based on complex magnetic permeability according to claim 1, wherein: The data processing device is provided with a data acquisition program for converting character string information into numerical value information.

3. The method for screening magnetic cores based on complex magnetic permeability as described in claim 2, wherein step S3 includes setting the communication port, baud rate, and bit rate of the data acquisition program work interface to be consistent with the communication port, baud rate, and bit rate of the data acquisition device, so that the data processing device is communicatively connected with the data acquisition device.

4. The method for screening magnetic cores based on complex magnetic permeability according to claim 2, wherein: Step S3 further includes: S31, after writing the character string information of the data acquisition device into the data acquisition program, the data acquisition program reads the character string information; S32: The data acquisition program splits the string information into two segments of string information. A separator is provided between the two segments of string information for separation. The string information before the separator is the string information of the series inductance Ls, and the string information after the separator is the string information of the quality factor Q. S33, converting the string information of the series inductor Ls in step S32 into the numerical information of the series inductor Ls; converting the string information of the quality factor Q in step S32 into the numerical information of the quality factor Q; S34. Display the numerical information obtained in step S33 through a display control.

5. The method for screening magnetic cores based on complex magnetic permeability according to claim 4, wherein: The step S31 also sets a total amount of character string information, and stops reading after the total amount of character string information is read.

6. The method for screening magnetic cores based on complex magnetic permeability according to claim 4, wherein: In step S32, a first character string length X1 and a second character string length X2 are set. The length of the character string information is separated into character string information of two lengths by the delimiter. The length of the character string information before the delimiter is the first character string length X1, and the length of the character string information after the delimiter is the second character string length X2. The character string information of the first character string length X1 before the delimiter is first read and recorded as the character string information of the series inductance Ls. Then, the character string information of the second character string length X2 after the delimiter is read and recorded as the character string information of the quality factor Q.

7. The method for screening magnetic cores based on complex magnetic permeability according to claim 6, wherein: The method also includes a verification method for the first character string length X1 and the second character string length X2. The verification method includes: first setting a first preset character string length X1 and a second character string length X2. 10 and the second preset string length X 20 , by first presetting the string length X 10 and the second preset string length X 20 The character string information is split to obtain two segments of character string information, the character string information before the separator is set as the first character string information, and the character string information after the separator is set as the second character string information, and the first character string information and the second character string information are converted into first numerical information and second numerical information respectively, and then it is determined whether the first numerical information and the second numerical information are equal to the numerical value of the series inductance Ls and the numerical value of the quality factor Q displayed on the data acquisition device. If the determination is yes, the first preset character string length X is set. 10 That is, the first character string length X1, the second preset character string length X 20 That is, the second character string length X2. If the judgment is no, the first preset character string length X is modified. 10 The length value and the second preset string length X 20 Length value, check again.

8. The method for screening magnetic cores based on complex magnetic permeability according to claim 6, wherein: In step S33, the character string information having the first character string length X1 is converted into numerical information, i.e., numerical information of the series inductance Ls is obtained; and the character string information having the second character string length X2 is converted into numerical information, i.e., numerical information of the quality factor Q is obtained.

9. The method for screening magnetic cores based on complex magnetic permeability according to claim 1, wherein: The data acquisition device is an LCR tester.

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