Method for measuring impedance of common mode inductor based on vector network analyzer

Abstract

The invention discloses a common mode inductor impedance measurement method based on a vector network analyzer, and the method comprises the steps: firstly constructing a measurement clamp, and obtaining the initial values of a clamp inductor L2 and a clamp capacitor C2 in the measurement clamp through the preliminary calibration of the distribution parameters of the measurement clamp; measuring admittance of the clamp and the common mode inductor by using a vector network analyzer, and further calculating an impedance curve of the common mode inductor; correcting initial values of a clamp inductor L2 and a clamp capacitor C2 based on an impedance analyzer; for the same batch of measurement clamps, re-calibration or correction is not needed, and the corrected clamp inductance L2 and clamp capacitance C2 values are adopted to calculate the impedance curve of the common mode inductor.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic component measurement, and more specifically, relates to a common mode inductor impedance measurement method based on a vector network analyzer. Background Art

[0002] Common-mode inductor impedance measurement is the basis of common-mode inductor filter design (F. Fan, KY See, X. Liu, et al., Systematic Common-Mode Filter Design for Inverter-Driven Motor System Based on in-Circuit Impedance Extraction, IEEE Transactions on Electromagnetic Compatibility [J], 2020, 62 (5): 1711-1722.). Common-mode inductor impedance measurement is mainly completed by impedance analyzers. However, impedance analyzers are relatively expensive and it is difficult to achieve large-scale industrial online detection and measurement.

[0003] To solve the above problems, a common mode inductor impedance measurement method based on vector network analyzer is proposed. However, due to the influence of cable contact capacitance (J.Yao, S.Wang and H.Zhao, Measurement Techniques of Common Mode Currents, Voltages, and Impedances in a Flyback Converter for Radiated Emi Diagnosis, IEEE Transactions on Electromagnetic Compatibility [J], 2019, 61 (6): 1997-2005.) and fixture distributed capacitance and distributed inductance (HM Jie, SPGao, ZY Zhao, et al., VNA-Based Fixture Adapters for Wideband Accurate Impedance Extraction of Single-Phase Emi Filtering Chokes, IEEE Transactions on Industrial Electronics [J], 2023, 70 (8): 7821-7831.), this method has large errors at high frequencies. J.Yao proposed a cable parasitic parameter compensation method to eliminate cable parasitic effects. HMJie uses a special fixture design method to eliminate the interference of fixture parasitic effects through a de-embedding process. The above methods rely on special fixtures with complex structures and are difficult to achieve large-scale industrial applications. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a common-mode inductor impedance measurement method based on a vector network analyzer, which can achieve high-precision measurement of common-mode inductance up to 120MHz by calibrating fixture distributed parameters through an algorithm.

[0005] To achieve the above-mentioned purpose of the invention, the present invention provides a common-mode inductor impedance measurement method based on a vector network analyzer, which is used for an inductor impedance measurement model composed of a common-mode inductor, a fixture and a vector network analyzer, wherein the common-mode inductor is welded on the fixture, and the welding endpoints are marked as c and d; the fixture is connected to the port1 and port2 terminals of the vector network analyzer, and the access endpoints are marked as a and b; it is characterized in that it includes the following steps:

[0006] (1) Build a measuring fixture;

[0007] (2) Obtain the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 in the measuring fixture by preliminarily calibrating the distributed parameters of the measuring fixture;

[0008] (3) Use a vector network analyzer to measure the admittance of the fixture and common-mode inductor;

[0009] (4) Calculate the impedance curve of the common-mode inductor based on the admittance of the fixture and the common-mode inductor, as well as the fixture inductance L2 and the fixture capacitance C2;

[0010] (5) Based on the impedance analyzer, correct the initial values ​​of the fixture inductance L2 and the fixture capacitance C2;

[0011] (6) All the measurement fixtures in the same batch use the corrected fixture inductance L2 and fixture capacitance C2 values ​​to calculate the impedance curve of the common-mode inductor.

[0012] The object of the invention of the present invention is achieved in this way:

[0013] The present invention provides a common-mode inductor impedance measurement method based on a vector network analyzer. First, a measuring fixture is constructed. The initial values ​​of the fixture inductance L2 and the fixture capacitance C2 in the measuring fixture are obtained by preliminarily calibrating the distributed parameters of the measuring fixture. Then, the admittance of the fixture and the common-mode inductor is measured by the vector network analyzer, and the impedance curve of the common-mode inductor is calculated. Then, the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 are corrected based on the impedance analyzer. For the same batch of measuring fixtures, no recalibration or correction is required, and the corrected fixture inductance L2 and fixture capacitance C2 values ​​are used to calculate the impedance curve of the common-mode inductor.

[0014] At the same time, the common mode inductor impedance measurement method based on the vector network analyzer of the present invention also has the following beneficial effects:

[0015] (1) The present invention proposes a method for measuring common-mode inductor impedance using a vector network analyzer and a fixture thereof, which achieves precise measurement of common-mode inductor impedance using a vector network analyzer at a frequency of up to 120 MHz.

[0016] (2) Compared with the method for eliminating the interference of fixture parasitic effects in the de-embedding process, the method of the present invention has a simple algorithm and high accuracy.

[0017] (3) The measuring fixture designed by the present invention does not need to be calibrated or corrected again after the distributed parameters of the fixture are calibrated, and is still applicable to the measurement of common-mode inductors with other inductance values.

[0018] (4) Compared with the traditional 120MHz impedance analyzer, the present invention has low hardware cost and is convenient for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a principle diagram of a common mode inductor impedance measurement method based on a vector network analyzer of the present invention;

[0020] Figure 2It is the calibration flow chart of the distributed parameters of the measuring fixture;

[0021] Figure 3 It is a comparison curve of common mode inductor impedance measured by vector network analyzer and impedance analyzer;

[0022] Figure 4 This is an example of measuring impedance curves using a vector network analyzer and an impedance analyzer. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0024] Example

[0025] Figure 1 It is a principle diagram of a common-mode inductor impedance measurement method based on a vector network analyzer of the present invention.

[0026] In this embodiment, the present invention provides a common-mode inductor impedance measurement method based on a vector network analyzer, which is used for an inductor impedance measurement model composed of a common-mode inductor, a fixture and a vector network analyzer, such as Figure 1 As shown, the common mode inductor is welded on the fixture, and the welding endpoints are marked as c and d; the fixture is connected to the port1 and port2 terminals of the vector network analyzer, and the access endpoints are marked as a and b;

[0027] exist Figure 1 In the figure, frame A is the equivalent circuit model of the common-mode inductor, including the equivalent resistance R1, the equivalent inductance L and the winding equivalent capacitance C1; frame B is the fixture equivalent circuit, including the fixture capacitance C2 and the fixture inductance L2; the fixture equivalent model proposed by J.Yao and HMJie is relatively complex, and is simplified to the form of frame B here. Frame C is the equivalent model of the vector network analyzer, including the AC signal source AC, the measurement resistor Rm and the vector voltmeter

[0028] Below we describe the common mode inductor impedance measurement process in detail, which includes the following steps:

[0029] (1) Build a measuring fixture;

[0030] The measuring fixture includes five component welding positions: TL1, TC1, TC2, P1 and P2, each welding position includes two endpoints; TL1 and TC1 are connected in parallel to form branch Z p Then, branch Zp is connected in series with TC2 to form branch Z s ; Finally, P1 and P2 are connected in series in branch Zs both ends of .

[0031] (2) Obtain the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 in the fixture through preliminary calibration of the fixture distribution parameters;

[0032] In this embodiment, if Figure 2 As shown in the first figure, the fixture includes two SMA interfaces, the inductor position TL1, the parallel capacitor position TC1, and the series capacitor position TC2. TL1 is connected in parallel with TC1, and the parallel circuit is connected in series with TC2. The two ends of the circuit are connected in series with SMA ports and connected to the vector network analyzer instrument.

[0033] Take the nominal inductance L3, nominal capacitance C3, C L During calibration, the nominal inductance L3 is mounted on the fixture TL1, the nominal capacitance C3 is mounted on the fixture TC1, and the nominal capacitance C is mounted on the fixture TC2. L Consider the circuit diagram under distributed parameters as follows Figure 2 As shown in the second figure. L3 and L2 are connected in series to form a series branch ②, and the equivalent inductance value of the series branch ② is recorded as L4; the series branch ② is connected in parallel with C2 and C3 to form a parallel branch ②; the equivalent capacitance value of C2 and C3 in parallel is C4; the equivalent capacitance value of the parallel branch ② and C L They are connected in series to construct an equivalent circuit for fixture calibration and connected to a vector network analyzer.

[0034] Will Figure 2 Simplify the second picture in the figure to get Figure 2 The equivalent circuit shown in the third figure is that L4 and C4 are connected in parallel to form a parallel branch ③, which is then connected to C L Connect in series, where L4=L2+L3; C4=C2+C3; finally connect the above circuit to a vector network analyzer.

[0035] The ZL202011292243.9 and IEEE Transactions on Instrumentation and Measurement, 2022, 71 methods are used to measure the common inductance L4 of the fixture and the nominal inductance, and the common capacitance C4 of the nominal capacitance and the distributed capacitance. That is, the fixture inductance can be calculated as L2=L4-L3; the fixture capacitance C2=C4-C3.

[0036] (3) Use a vector network analyzer to measure the admittance of the fixture and common-mode inductor;

[0037] Based on the above measurement fixture, a common mode inductor is soldered at TL1, TC1 is left floating, and TC2 is directly short-circuited. P1 and P2 are soldered to SMA ports and connected to the vector network analyzer.

[0038] like Figure 2In the fixture model shown in the first figure, TC1 is left floating, TC2 is directly connected, a common-mode inductor is inserted at TL1, and then connected to a vector network analyzer;

[0039] Set the frequency range of the vector network analyzer to 0-120MHz and the measurement mode to S21 Smith; then take values ​​within the frequency range and measure different frequencies f i The corresponding admittance data is as follows, and the real part of admittance is recorded as A i and the imaginary part of admittance is B i , i=1,2,…,n, n represents the number of frequency sampling points.

[0040] (4) Calculate the impedance curve of the common-mode inductor based on the admittance of the fixture and the common-mode inductor, as well as the fixture inductance L2 and the fixture capacitance C2;

[0041] make Figure 1 The complex impedance between points cd is Z1(ω), and the complex impedance between points ab is:

[0042]

[0043] From CN202011292243.9, we can know that the complex admittance between points ab obtained by the Smith chart of the vector network analyzer is

[0044]

[0045] According to the admittance data measured in step (2): f i is the frequency point of the frequency sweep and has an angular frequency ω i =2πf i , A i is the real part of the admittance G(ω), B i is the imaginary part of the admittance G(ω), then the complex admittance G(ω) at each frequency point can be expressed as:

[0046] G(ω i )=A i +jB i (3)

[0047] (3) Inductor impedance measurement algorithm based on vector network analyzer

[0048] From equation (2) and equation (3), we can get:

[0049]

[0050] Then the complex impedance between points a and b is:

[0051]

[0052] Formula (5) is the measured impedance of points ab, and formula (1) is the analytical expression of the impedance between points ab. The two are equal when combined, that is,

[0053]

[0054] In formula (6), ω i =2πf i get:

[0055]

[0056] In equation (7), the right side is the measured value, and the left side is the analytical expression of the impedance between points ab. The impedance Z1(2πf i ) is the quantity to be solved, j2πfL2 and j2πfC2 are the inductance and capacitance represented by the fixture and wire distributed parameters respectively.

[0057] The inductor impedance Z1(2πf can be inverted by measuring the distributed inductance j2πfL2 and distributed capacitance j2πfC2 through equation (7): i ).make:

[0058] Z3(2πf i )=Z1(2πf i )+j2πf i L2 (8)

[0059] Formula (7) is simplified as:

[0060]

[0061] in,

[0062] Solving equation (9) yields:

[0063]

[0064] The complex impedance of the inductor is obtained from equation (8):

[0065]

[0066] Impedance Z Inductance The modulus of its complex impedance, that is, the square root of the sum of the squares of the real and imaginary parts of the impedance, is represented by the mathematical operator abs(), and the measured impedance is:

[0067] y i =abs(Z1(2πf i )) (12)

[0068] (5) Correct the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 to obtain the corrected impedance curve of the mold inductor;

[0069] (5.1), generate L2 and C2 grids;

[0070] Taking the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 as a reference, multiple points are taken on both sides of L2 and C2 at a fixed step to obtain a series of grid points consisting of inductance values ​​and capacitance values;

[0071] (5.2) Substitute a set of inductance and capacitance values ​​corresponding to each grid point in the L2 and C2 grids into the common-mode inductor impedance curve to obtain the common-mode inductor impedance curve corresponding to each grid point, where the common-mode inductor impedance curve corresponding to the j-th grid point is y i_j ,y i_j The corresponding inductance and capacitance values ​​are L 2j , C 2j ;

[0072] (5.3) With the same fixture and common-mode inductor, the impedance curve measured by the impedance analyzer is Y i The common mode inductor impedance curve calculated at each grid point is y i_j . Calculate the root mean square error between the two curves at each grid point;

[0073]

[0074] (5.4), select the minimum root mean square error, denoted as RMSE min ; If the root mean square error RMSE min Less than the set value RMSE set , that is, RMSE min <RMSE set , then save RMSE min The corresponding L 2j , C 2j ,y i_j , then go to step (5.5); otherwise, reduce the step size of L2 and C2, further refine the grid spacing, and then return to step (5.1) for the next round of iteration; if RMSE is still not satisfied after k consecutive iterations min <RMSE set , then compare the minimum root mean square error RMSE after the kth iteration min_k The minimum root mean square error RMSE after the k-1th iteration min_k-1 Is the difference less than the threshold RMSE? Δ If satisfied, the iteration ends and RMSE is saved min_k The corresponding L 2j , C 2j ,y i_j ; Otherwise, continue to further refine the grid spacing and return to step (5.1);

[0075] (5.5) Output the values ​​of the corrected fixture inductance L2 and fixture capacitance C2 of the measurement fixture, L2 = L 2j , C2=C 2j .

[0076] Finally, for the fixtures of the same batch, there is no need to calibrate or correct them again, and the impedance curve of the common-mode inductor is calculated using the corrected fixture inductance L2 and fixture capacitance C2 values.

[0077] Example verification

[0078] 1. Example of measuring the nominal 28.5uH common mode inductor impedance;

[0079] The implementation equipment includes PCB board fixture, common mode inductor, vector network analyzer and PC. The fixture port is connected to the vector network analyzer through a coaxial cable. Here, the vector network analyzer is the TR1300 / 1 model of CopperMountain. First, the fixture distributed inductance and distributed capacitance are calibrated. Then the vector network analyzer measures the common mode inductor admittance. Finally, the admittance data is imported into the impedance curve to calculate the impedance of the common mode inductor.

[0080] The specific implementation steps are as follows:

[0081] (1) Preliminary calibration of fixture distribution parameters.

[0082] Figure 2 The nominal inductor L3 = 4.7uH is mounted at TL1 of the middle fixture, the nominal capacitor C3 = 10pF is mounted at TC1, and the nominal capacitor 47pF is mounted at TC2. The inductance L4 of the fixture and the nominal inductance is measured by the ZL202011292243.9 and IEEE Transactions on Instrumentation and Measurement, 2022, 71 methods, and the capacitance C4 of the nominal capacitance and the distributed capacitance is measured. The measurement results are L4 = 5.01uH, C4 = 11.49pF.

[0083] Then the distributed inductance L2 of the fixture is L4-L3=5.01uH-4.7uH=0.31uH, and the distributed capacitance C2=C4-C3=11.49pF-10pF=1.49pF.

[0084] (2) Measure the common-mode inductance and the admittance of the fixture.

[0085] In the fixture model, TC1 is suspended, TC2 is directly connected, and a common-mode inductor is inserted into TL1, and then connected to the vector network analyzer. The frequency range of the vector network analyzer is set to 0-120MHz, and the measurement mode is set to S21 Smith. The array of admittance data obtained by the vector network analyzer is 3 columns of data, each column is a frequency f i 、Real part of admittance A i and the imaginary part of admittance B i , and then calculate the impedance of the common mode inductor at each frequency point using the data impedance curve at each frequency point, such as Figure 3 Shown by the solid line.

[0086] (3) Precision calibration of distributed parameters based on impedance analyzer measurement data.

[0087] Due to the errors between the nominal and true values ​​of the nominal inductors and capacitors, the differences between the distributed parameters of the vector network analyzer and the distributed parameters of the impedance analyzer, Figure 3 The common mode inductance measured by the two instruments has a large error in high frequency state. Next, the impedance analyzer is calibrated to the vector network analyzer.

[0088] ① Impedance curve fitting measured by impedance analyzer

[0089] For the same set of common mode inductors, the impedance curve measured by the impedance analyzer is [XX t ,YY t ], where XX t is the frequency, YY t is the impedance, such as Figure 3 As shown by the dashed line in the middle. Since two instruments are used for measurement, it is very likely that the operators use different frequency spacing standards. For example, the frequency data XX of the impedance analyzer in this experiment t Using logarithmic coordinates and equal spacing, the vector network analyzer frequency data X t The frequency coordinates of the two instruments are inconsistent, which makes calculation impossible.

[0090] Therefore, it is necessary to fit the impedance curve measured by the impedance analyzer and interpolate it into the frequency coordinate f of the vector network analyzer. i The corresponding impedance. Here, a 9th-order polynomial is used to fit the impedance curve measured by the impedance analyzer. The frequency coordinate f of the vector network analyzer is calculated by interpolation of the fitting curve. i The corresponding impedance Y i Then, the impedance curve measured by the impedance analyzer is [f i ,Y i ].

[0091] ②Generate L2 and C2 grids;

[0092] Set the inductor array L2X: [Linitial -L range :L_ space :L initial +L range ]. According to step (1), L2 is around 0.31uH. Set L initial =0.31uH, L range =0.1uH, L_ space =0.1uH. Then L2X is the array [0.21:0.1:0.41]*uH.

[0093] Set the capacitor array: C2X:[C initial -C range :C_ space :C initial +C range ], according to step (1), L2 C2 is around 1.49pF. Set C initial =1.49pF, C range =1.49pF, C space =1pF. Then C2X is the array [0:1:2.98]*uH.

[0094] ③ Calculate the common mode inductor impedance curve of L2 and C2 grid points, and obtain the common mode inductor impedance curve y measured by the vector network analyzer i =Z Inductance (f i ).

[0095] ④ Calculate the root mean square error of the impedance curve of the impedance analyzer corresponding to the L2 and C2 grid points and the impedance curve of the vector network analyzer. By traversing the root mean square error corresponding to each grid point, it can be found that the minimum root mean square error occurs at the grid point L2 = 0.388uH, C2 = 0.08pF, RMSE = 14.40. The impedance curve measured by the vector network analyzer and the impedance curve measured by the impedance analyzer are compared. Figure 4 shown.

[0096] Example of measuring the impedance of a nominal 350uH common mode inductor;

[0097] The same batch of fixtures as in the example of measuring the nominal 28.5uH common mode inductor impedance are used to measure the nominal 350uH common mode inductor impedance. Since the fixtures are from the same batch, the same fixture parameters are used, namely L2 = 0.388uH, C2 = 0.08pF. The calculated RMSE_min = 41.95.

[0098] The 350uH common-mode inductor and its fixture are calibrated with an impedance analyzer, and the operation in the nominal 28.5uH common-mode inductor impedance measurement example is repeated. The calculation results are as follows: L2 = 0.45uH, C2 = 0.005pF, RMSE = 41.80.

[0099] By comparison, it can be found that the error between the two is 0.35%. This error may come from the error of the fixtures in the same batch or the error caused by the inconsistent environment in the experimental project.

[0100] Although the above describes the illustrative specific embodiments of the present invention to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

Claims

1. A common-mode inductor impedance measurement method based on a vector network analyzer is used for an inductor impedance measurement model composed of a common-mode inductor, a fixture and a vector network analyzer, wherein: The common mode inductor is welded on the fixture, and the welding endpoints are marked as c and d; the fixture is connected to the port1 and port2 terminals of the vector network analyzer, and the access endpoints are marked as a and b; the method is characterized in that it includes the following steps: (1) Build a measuring fixture; (2) Obtain the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 in the measuring fixture by preliminarily calibrating the distributed parameters of the measuring fixture; (3) Use a vector network analyzer to measure the admittance of the fixture and common-mode inductor; (4) Calculate the impedance curve of the common-mode inductor based on the admittance of the fixture and the common-mode inductor, as well as the fixture inductance L2 and the fixture capacitance C2; (5) Based on the impedance analyzer, correct the initial values ​​of the fixture inductance L2 and the fixture capacitance C2; (6) All the measurement fixtures in the same batch use the corrected fixture inductance L2 and fixture capacitance C2 values ​​to calculate the impedance curve of the common-mode inductor.

2. The common mode inductor impedance measurement method based on a vector network analyzer according to claim 1, characterized in that: The measuring fixture comprises: TL1, TC1, TC2, P1 and P2, a total of five component welding positions, each welding position comprises two end points; wherein TL1 and TC1 are connected in parallel to form a branch Z p ; Then, branch Z p Connected in series with TC2 to form branch Z s ; Finally, P1 and P2 are connected in series in branch Z s both ends of .

3. The common mode inductor impedance measurement method based on a vector network analyzer according to claim 1, characterized in that: The method for obtaining the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 is: (3.1), take the nominal inductance L3, nominal capacitance C3, C L , connect the circuit of the measuring fixture; On the measuring fixture, the nominal inductor L3 is mounted at TL1, the nominal capacitor C3 is mounted at TC1, and the nominal capacitor C is mounted at TC2. L , P1 and P2 are soldered to SMA ports and connected to the vector network analyzer; (3.2) Obtain the equivalent circuit when measuring the initial values ​​of the fixture inductance L2 and the fixture capacitance C2; Connect the nominal inductance L3 and the fixture inductance L2 in series, and denote the series branch as Z s1 ; Then connect the fixture capacitor C2 and the nominal capacitor C3 in parallel in the series branch Z s1 At both ends, the total parallel branch is Z p ;;Finally, the nominal capacitance C L Tandem Z p On the branch, an equivalent circuit for fixture calibration is constructed; (3.3), simplified equivalent circuit; The equivalent inductance value of the nominal inductance L3 and the fixture inductance L2 in series is recorded as L4, and the equivalent capacitance value of the fixture capacitance C2 and the nominal capacitance C3 in parallel is recorded as C4. Then the model built in step (3.2) is simplified to: the equivalent inductance L4 and the equivalent capacitance C4 are connected in parallel to form a parallel branch Z p , parallel branch Z p Then with the nominal capacitance C L Series connection; In the simplified equivalent circuit, the nominal inductance L4 is not connected to the nominal capacitance C L The connected end is the access terminal a, and the nominal capacitance is C. L The end not connected to the equivalent capacitor C4 is accessed as terminal b, and then connected to the vector network analyzer; (3.4) Obtain the initial values ​​of the fixture inductance L2 and the fixture capacitance C2; Measure the equivalent inductance L4 and the equivalent capacitance C4, and then calculate the fixture inductance as L2=L4-L3; the fixture capacitance C2=C4-C3.

4. The common mode inductor impedance measurement method based on a vector network analyzer according to claim 1, characterized in that: The admittance measurement method of the fixture and common mode inductor is: (4.1) Solder the common mode inductor at TL1 in the measurement fixture, leave TC1 unconnected, short-circuit TC2, solder SMA ports at P1 and P2 and connect to the vector network analyzer; (4.2) Set the frequency range of the vector network analyzer to 0-120MHz and the measurement mode to S21Smith; then take values ​​within the frequency range and measure different frequencies f i The corresponding admittance data is as follows, and the real part of admittance is recorded as A i and the imaginary part of admittance is B i , i=1,2,…,n, n represents the number of frequency sampling points.

5. The common mode inductor impedance measurement method based on a vector network analyzer according to claim 1, characterized in that: The common mode inductor impedance curve is: y i =abs(Z1(2πf i )) Among them, y i represents the impedance curve of the common mode inductor calculated at the i-th frequency point, f i represents the i-th frequency point measured by the vector network analyzer, A i , B i Indicates frequency f i The real and imaginary parts of the measured admittance data are shown below; abs( ) represents the modulus, Z1(2πf i ) is the complex impedance of the common-mode inductor, Z m (ω i )=Z m (2πf i ) is the complex impedance between the two end points a and b, R m is the measurement resistance of the vector network analyzer.

6. The common mode inductor impedance measurement method based on a vector network analyzer according to claim 1, characterized in that: The correction method for the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 is: (6.1), generate L2 and C2 grids; Taking the initial values ​​of the fixture inductance L2 and the fixture capacitance C2 as a reference, multiple points are taken on both sides of L2 and C2 at a fixed step to obtain a series of grid points consisting of inductance values ​​and capacitance values; (6.2) Substitute a set of inductance and capacitance values ​​corresponding to each grid point in the L2 and C2 grids into the common-mode inductor impedance curve to obtain the common-mode inductor impedance curve corresponding to each grid point, where the common-mode inductor impedance curve corresponding to the j-th grid point is y i_j ,y i_j The corresponding inductance and capacitance values ​​are L 2j , C 2j ; (6.3) The impedance curve measured by the impedance analyzer with the same fixture and common mode inductor is Y i The common mode inductor impedance curve calculated at each grid point is y i_j . Calculate the root mean square error between the two curves at each grid point; (6.4), select the minimum root mean square error, denoted as RMSE min ; If the root mean square error RMSE min Less than the set value RMSE set , that is, RMSE min <RMSE set , then save RMSE min The corresponding L 2j , C 2j ,y i_j , then go to step (6.5); otherwise, reduce the step size of L2 and C2, further refine the grid spacing, and then return to step (6.1) for the next round of iteration; if RMSE is still not satisfied after k consecutive iterations min <RMSE set , then compare the minimum root mean square error RMSE after the kth iteration min_k The minimum root mean square error RMSE after the k-1th iteration min_k-1 Is the difference less than the threshold RMSE? Δ If satisfied, the iteration ends and RMSE is saved min_k The corresponding L 2j , C 2j ,y i_j ; Otherwise, continue to further refine the grid spacing and return to step (6.1); (6.5) Output the corrected fixture inductance L2 and fixture capacitance C2 values ​​of the measurement fixture, L2 = L 2j , C2=C 2j .

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