Method for determining self-healing area effect of metallized film

Abstract

The invention belongs to the technical field of metallized film capacitor testing, and particularly relates to a metallized film self-healing area effect determination method, which comprises the following steps: preparing metallized film samples with different areas, and carrying out breakdown and self-healing experiments to obtain data sets of breakdown field strength and corresponding self-healing characteristic parameters under different areas; determining expressions of self-healing characteristic parameters, breakdown field strength and metalized film sample area according to the data set, and determining distribution characteristics of the self-healing characteristic parameters according to distribution characteristics of the breakdown field strength; according to the area effect of the breakdown field strength and the distribution characteristics of the self-healing characteristic parameters, the relation between the self-healing characteristic parameters and the area is obtained. According to the method, the relation between the breakdown field strength and the self-healing characteristic parameters and the distribution characteristics of the self-healing characteristic parameters are reasonably considered, the relation between the self-healing characteristic parameters and the area is obtained, the whole derivation process is rigorous, calculation is accurate and easy to implement, and an important basis is provided for design and application of the large-area metallized film.

Description

Technical Field

[0001] The invention belongs to the technical field of metallized film capacitor testing, and particularly relates to a method for determining a self-healing area effect of a metallized film. Background Art

[0002] The self-healing properties of metallized film are a key indicator of the insulation reliability and lifespan of metallized film capacitors. Accurately estimating the self-healing properties of metallized film and designing appropriate insulation are crucial to avoiding the risk of capacitor failure due to short-circuit breakdown.

[0003] When evaluating the self-healing properties of metallized films, the area effect of self-healing is an inevitable problem in engineering. The area effect of self-healing is the phenomenon that the self-healing performance decreases as the area of the metallized film increases. In the test methods recommended by relevant standards, the test objects are generally small-area metallized films, that is, an area of 20 cm 2 However, the area of metallized film capacitors used in actual projects may be 100 to 1,000 times, or even tens of thousands of times, the size of the test object. In this case, the increase in metallized film area will lead to a significant decrease in self-healing performance. If the test results are directly used as a reference, there is a risk of capacitor life being too short or even short-circuiting and sintering in engineering applications. Therefore, fully considering the impact of the self-healing area effect is extremely important for accurately predicting the self-healing characteristics of large-area metallized films.

[0004] Traditional methods for calculating the self-healing area effect rely on simple empirical formulas, such as the assumption that the self-healing energy is a power-exponential function of the area. However, because they fail to consider the crucial relationship between breakdown field strength and the characteristic self-healing parameters, empirical formulas derived from experiments are nearly impossible to apply in practice. The calculated results are often significantly higher than the actual values, leading to overly conservative capacitor parameter design and excessive margins. Furthermore, traditional methods ignore the distribution characteristics of the characteristic self-healing parameters, resulting in calculations that fail to accurately describe their dispersion. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for determining the self-healing area effect of a metallized film. Based on the connection between the breakdown field strength and the self-healing characteristic parameters and the distribution characteristics of the self-healing characteristic parameters, the relationship between the self-healing characteristic parameters and the area of the metallized film is obtained, providing an important basis for the design and application of large-area metallized films.

[0006] To achieve the above object, the present invention provides a method for determining the self-healing area effect of a metallized film, comprising:

[0007] Step S1: preparing metallized film samples of different areas, conducting breakdown and self-healing experiments, and obtaining data sets of breakdown field strength and corresponding self-healing characteristic parameters under different areas;

[0008] Step S2: determining an expression of the self-healing characteristic parameter, the breakdown field strength, and the area of the metallized film sample according to the data set, and determining the distribution characteristics of the self-healing characteristic parameter according to the distribution characteristics of the breakdown field strength;

[0009] Step S3: according to the area effect of the breakdown field strength and the distribution characteristics of the self-healing characteristic parameter, the relationship between the self-healing characteristic parameter and the area of the metallized film is obtained.

[0010] Furthermore, in step S1, two metallized film samples are stacked with their metal surfaces facing upwards, and then placed in a metallized film self-healing device for breakdown and self-healing experiments; the stacking area is the area A of the metallized film sample.

[0011] Furthermore, in step S1, the metallized film sample is a polymer film with a metal film coated on the surface, the thickness of the polymer film is 1-20 μm, and the metal film is a zinc film or an aluminum film with a thickness of 2-20 nm.

[0012] Furthermore, the polymer film is a PP film, a PET film, a PEN film or a PI film.

[0013] Furthermore, in step S1, the number of the metallized film samples corresponding to each area is not less than 30 groups; the area of the metallized film sample is 10-80cm 2 .

[0014] Furthermore, in step S1, the self-healing characteristic parameters include the self-healing energy W sh , self-healing area S sh , self-healing duration t sh .

[0015] Furthermore, in step S2, the expressions of the self-healing characteristic parameters, the breakdown field strength, and the area of the metallized film sample are as follows:

[0016] C sh =g1(E b )·g2(A)

[0017] Among them, C sh is the self-healing characteristic parameter, E b is the breakdown field strength; g1(E b ) is the relationship function between the self-healing characteristic parameter and the breakdown field strength, g2(A) is the relationship function between the self-healing characteristic parameter and the area, g1(E b ) and g2(A) are power exponential or linear functions obtained by fitting the data set.

[0018] Furthermore, the self-healing energy W in the self-healing characteristic parameter sh The expression of breakdown field strength and metallized film sample area is as follows:

[0019]

[0020] Wherein, m, n, and k are constant coefficients, and their values are obtained by fitting the data set.

[0021] Furthermore, the distribution characteristic of the breakdown field strength is Weibull distribution, normal distribution or Gumbel distribution; the form of the Weibull distribution is as follows:

[0022]

[0023] Among them, F(E b ) represents the breakdown field strength E b The cumulative probability of , α is the scale parameter, β is the shape parameter;

[0024] The breakdown field strength E in formula (1) b Substituting into formula (2) we can get the self-healing energy W sh Distribution characteristics:

[0025]

[0026] Furthermore, the area effect of the breakdown field strength is obtained using Weibull distribution:

[0027]

[0028] Among them, α1 and β1 represent the scale parameter and shape parameter of the Weibull distribution under area A1, respectively, and a2 and β2 represent the scale parameter and shape parameter of the Weibull distribution under area A2, respectively.

[0029] Furthermore, according to the data obtained from the experiment of the metallized film sample of one group of areas, the values of α and β under the area in formula (2) are determined, and α and β under the area are used as a2 and β2 in formula (4), and the corresponding area is used as A2 in formula (4). Substitute them into formula (4) to obtain α1 and β1, and substitute α1 and β1 into α and β in formula (3) respectively, and make the cumulative probability F(W) of formula (3) sh ) is 63.2% and the relationship between self-healing energy and area is obtained.

[0030] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0031] 1. The method for determining the self-healing area effect of metallized films provided by the present invention is based on the connection between breakdown field strength and self-healing characteristic parameters, as well as the distribution characteristics of the self-healing characteristic parameters, to obtain the relationship between the self-healing characteristic parameters and area. The entire derivation process is scientific and rigorous, and the calculation is accurate and easy to perform, providing an important basis for the design and application of large-area metallized films.

[0032] 2. Furthermore, the present invention uses a Weibull distribution to determine the distribution characteristics of the breakdown field strength. Simultaneously, based on data from breakdown and self-healing experiments, the relationship between the self-healing characteristic parameter, the breakdown field strength, and the area is fitted. The breakdown field strength-area effect is then incorporated into the distribution characteristics of the breakdown field strength to obtain the distribution characteristics of the self-healing characteristic parameter. This relationship between the self-healing characteristic parameter and the area can then be derived based on the cumulative probability. This method is applicable to determining the self-healing area effect of various metallized films and has strong universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A flow chart showing the self-healing area effect of a metallized film according to an embodiment of the present invention;

[0034] Figure 2 This is a graph showing the calculation results of the self-healing energy of the metallized film provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0036] See Figure 1 , which is a flow chart of a method for determining the self-healing area effect of a metallized film according to an embodiment of the present invention. The following describes in detail a method for calculating the size effect of dielectric breakdown, including steps S1-S3.

[0037] Step S1: Prepare metallized film samples of different areas, conduct breakdown and self-healing experiments, and obtain data sets of breakdown field strength and corresponding self-healing characteristic parameters under different areas. The metallized film is a polymer film with a metal film on the surface, and the polymer film is a polypropylene film, PET film, PEN film, PI film, etc., with a thickness of 1-20μm, and the metal film is a zinc film or aluminum film with a thickness of 2-20nm. The area of the metallized film sample is 10-100cm 2 , for example 10cm 2 , 12cm 2 , 16cm 2 、18cm 2, 20cm 2 , 24cm 2 , 28cm 2 , 30cm 2 、32cm 2 、36cm 2 , 40cm 2 、46cm 2 、48cm 2 、64cm 2 , 80cm 2 wait.

[0038] The environmental conditions for metallized film testing should be similar to the operating or application conditions to reduce the interference of environmental conditions on the area effect calculation. The breakdown field strength and self-healing characteristic parameters obtained from the test should include no less than 30 sets of data, preferably 40-80 sets, to reduce the interference of accidental factors on the area effect calculation.

[0039] The experimental variable is only area A and there are at least two condition groups, controlling the temperature, pressure, metallized film material and other conditions unchanged. The metallized film breakdown and self-healing experimental samples adopt a double-layer stacking structure, and the overlapping area is the corresponding area A. The double-layer stacking structure is to place the two metallized film samples with the metal surface facing up and stacked, and then place them in a metallized film self-healing device for breakdown and self-healing experiments (for details, please refer to the metallized film breakdown self-healing device and method under DC voltage recorded in the prior patent application CN202311346617.4).

[0040] The self-healing characteristic parameters include the self-healing energy W sh , self-healing area S sh , self-healing duration t sh Common parameters such as the voltage and current waveforms are obtained from the experimental data and sample observations.

[0041] Step S2, self-healing characteristic parameter C sh and breakdown field strength E b The relationship expression of area A is obtained by fitting the experimental data of step S1, namely:

[0042] C sh =g1(E b )·g2(A)(1)

[0043] Among them, C sh is the corresponding self-healing characteristic parameter, E b is the breakdown field strength; g1(E b) is the function of the relationship between the self-healing characteristic parameter and the breakdown field strength. The form of the shell is determined by searching the literature and experimental data, such as a power exponential, a linear function, etc.; g2(A) is the function of the relationship between the self-healing characteristic parameter and the area. The form is determined by experimental data, usually a power exponential or a linear function. For example, in some scenarios, the self-healing energy W sh Breakdown field strength E b , area A meets the following relationship:

[0044]

[0045] Among them, m, n, and k are constant coefficients.

[0046] Then, the distribution characteristics of the self-healing characteristic parameters are determined. The distribution characteristics of the self-healing characteristic parameters are derived from the distribution characteristics of the breakdown field strength and the expression between the self-healing characteristic parameters and the breakdown field strength. The cumulative probability distribution of the breakdown field strength satisfies:

[0047] F(E b )=g3(E b ) (3)

[0048] Among them, F(E b ) represents the breakdown field strength E b The cumulative probability of g3(E b ) is the cumulative probability distribution form of the breakdown field strength, which is usually determined by searching literature or experimental data, including Weibull distribution, normal distribution, Gumbel distribution, etc. The most common distribution form is Weibull distribution, which is:

[0049]

[0050] Where α is the scale parameter and β is the shape parameter. Substituting the expression (2) between the self-healing characteristic parameter and the breakdown field strength and area into the above formula (4), the distribution form of the self-healing characteristic parameter can be obtained, namely:

[0051] F(C sh )=g4(C sh )(5)

[0052] Among them, F(C sh ) represents the self-healing characteristic parameter C sh The cumulative probability of g4(C sh ) is the cumulative probability distribution form of the self-healing characteristic parameter. For example, in some embodiments, the self-healing energy W sh The distribution form is:

[0053]

[0054] Step S3, self-healing characteristic parameter C shThe area effect calculation method should consider the area effect of the breakdown field strength on the distribution characteristics of the self-healing characteristic parameters.

[0055] Specifically, the calculation method of the area effect of the breakdown field strength can be obtained by searching the literature or experimental data. Preferably, the calculation method of the area effect of the breakdown field strength based on the Weibull distribution is adopted, that is:

[0056]

[0057] Where α1 and β1 represent the Weibull scale and shape parameters under area A1, respectively, and a2 and β2 represent the Weibull scale and shape parameters under area A2, respectively. Substituting the area effect calculation expression (7) of the breakdown field strength into the distribution expression (6) of the self-healing characteristic parameter, we can obtain the area effect calculation method of the self-healing characteristic parameter.

[0058] The following is a specific example to illustrate this method. 2 、32cm 2 、48cm 2 The polypropylene film was used as the sample (the metal film was an aluminum film with a thickness of 7nm). According to the breakdown self-healing and experimental method of the double-layer metallized film, the experiment was carried out (for details, please refer to the metallized film breakdown self-healing device and method under DC voltage described in the prior patent application CN202311346617.4), and the breakdown field strength and self-healing energy of the sample were measured. The number of measurement samples corresponding to each area of the film was 60. According to the obtained data set, the power exponent and the linear relationship function were used to fit the self-healing energy W sh and breakdown field strength E b , and the area A, we get mk = 0.076 × 10 -7 , n = 2.8, that is:

[0059]

[0060] The breakdown field intensity distribution was fitted using Weibull distribution, and the area was 32cm 2 α=622V / μm,β=7.2(It should be noted that other experimental areas (usually greater than or equal to 10cm) can also be selected here. 2 ) data to obtain the corresponding parameters, and the final error in the relationship between the self-healing energy and the area is within 5%. According to the area effect prediction method of the breakdown field strength, the breakdown distribution parameters under other areas can be obtained:

[0061]

[0062] Substituting the area effect law of α and β into the self-healing energy distribution formula (6), we can obtain:

[0063]

[0064] The area effect calculation method of breakdown field strength based on Weibull distribution is used to calculate the area effect of self-healing energy, and the self-healing energy W with a cumulative probability of 63.2% (i.e., Equation 10 is equal to 63.2%) is selected. a As parameters characterizing the overall self-healing energy, there are:

[0065]

[0066] The final calculation curves under different areas are as follows Figure 2 shown.

[0067] In summary, the method for determining the self-healing area effect of metallized films provided by the present invention rationally considers the relationship between breakdown field strength and self-healing characteristic parameters, as well as the distribution characteristics of the self-healing characteristic parameters, to obtain the relationship between the self-healing characteristic parameters and area. The entire derivation process is scientific and rigorous, the calculation is accurate and easy, and the universality is strong, providing an important basis for the design and application of large-area metallized films.

[0068] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining the self-healing area effect of a metallized film, characterized in that: include: Step S1: preparing metallized film samples of different areas, conducting breakdown and self-healing experiments, and obtaining data sets of breakdown field strength and corresponding self-healing characteristic parameters under different areas; Step S2: determining an expression of the self-healing characteristic parameter, the breakdown field strength, and the area of the metallized film sample according to the data set, and determining the distribution characteristics of the self-healing characteristic parameter according to the distribution characteristics of the breakdown field strength; Step S3: according to the area effect of the breakdown field strength and the distribution characteristics of the self-healing characteristic parameter, the relationship between the self-healing characteristic parameter and the area of the metallized film is obtained.

2. The method for determining the self-healing area effect of a metallized film according to claim 1, characterized in that: In step S1, two metallized film samples are stacked with their metal surfaces facing upwards, and then placed in a metallized film self-healing device for breakdown and self-healing experiments; the stacking area is the area A of the metallized film sample.

3. The method for determining the self-healing area effect of a metallized film according to claim 1, wherein: In step S1, the metallized film sample is a polymer film with a metal film coated on the surface, the thickness of the polymer film is 1-20 μm, and the metal film is a zinc film or an aluminum film with a thickness of 2-20 nm; And / or, the polymer film is a PP film, a PET film, a PEN film or a PI film.

4. The method for determining the self-healing area effect of a metallized film according to claim 1, wherein: In step S1, the number of the metallized film samples corresponding to each area is not less than 30 groups; the area of the metallized film sample is 10-80cm 2 .

5. The method for determining the self-healing area effect of a metallized film according to claim 1, wherein: In step S1, the self-healing characteristic parameters include the self-healing energy W sh , self-healing area S sh , self-healing duration t sh .

6. The method for determining the self-healing area effect of a metallized film according to any one of claims 1 to 5, characterized in that: In step S2, the expressions of the self-healing characteristic parameters, the breakdown field strength, and the area of the metallized film sample are as follows: C sh =g1(E b )·g2(A)(1) Among them, C sh is the self-healing characteristic parameter, E b is the breakdown field strength; g1(E b ) is the relationship function between the self-healing characteristic parameter and the breakdown field strength, g2(A) is the relationship function between the self-healing characteristic parameter and the area, g1(E b ) and g2(A) are power exponential or linear functions obtained by fitting the data set, and A is the area of the metallized film sample.

7. The method for determining the self-healing area effect of a metallized film according to claim 6, wherein: The self-healing energy W in the self-healing characteristic parameter sh The expression of breakdown field strength and metallized film sample area is as follows: Wherein, m, n, and k are constant coefficients, and their values are obtained by fitting the data set.

8. The method for determining the self-healing area effect of a metallized film according to claim 7, wherein: The distribution characteristics of the breakdown field strength are Weibull distribution, normal distribution or Gumbel distribution; the form of the Weibull distribution is as follows: Among them, F(E b ) represents the breakdown field strength E b The cumulative probability of , α is the scale parameter, β is the shape parameter; The breakdown field strength E in formula (2) b Substituting into formula (3) we can get the self-healing energy W sh Distribution characteristics:

9. The method for determining the self-healing area effect of a metallized film according to claim 8, wherein: The area effect of the breakdown field strength is obtained using Weibull distribution: Among them, α1 and β1 represent the scale parameter and shape parameter of the Weibull distribution under area A1, respectively, and a2 and β2 represent the scale parameter and shape parameter of the Weibull distribution under area A2, respectively.

10. The method for determining the self-healing area effect of a metallized film according to claim 9, wherein: According to the data obtained from the experiment of metallized film samples of one group of areas, the values of α and β under the area in formula (3) are determined, and α and β under the area are used as a2 and β2 in formula (5), and the corresponding area is used as A2 in formula (5). Substitute them into formula (5) to obtain α1 and β1, and substitute α1 and β1 into α and β in formula (4) respectively, and make the cumulative probability F(W) of formula (4) sh ) is 63.2%, which means the relationship between self-healing energy and area is obtained.

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