Electrolytic capacitor electrolytic paper esr measurement method and measurement system simulating winding working condition

Abstract

This invention relates to the field of capacitor material testing technology, specifically to a method and system for measuring the ESR of electrolytic paper in electrolytic capacitors under simulated winding conditions. The method includes the following steps: calculating the equivalent test pressure based on winding parameters; sequentially stacking 1 to n layers of electrolyte-impregnated electrolytic paper in a sealed, temperature-controlled environment chamber and performing wide-band frequency sweep measurements; then performing least-squares linear regression on the "number of stacked layers - total resistance" data set at each frequency point; eliminating contact resistance included in the intercept by extracting the slope of the fitted straight line, thereby accurately extracting the true ESR value of a single layer of electrolytic paper; and finally obtaining the ESR-frequency characteristic curves at different temperatures. This invention, based on pressure condition simulation and multi-layer stacked linear fitting, has outstanding advantages such as high measurement accuracy, realistic condition reproduction, good data repeatability, and comprehensive frequency characteristics. It is applicable to the research and development of aluminum electrolytic capacitor materials and industrial quality control.

Description

Technical Field

[0001] This invention relates to the field of capacitor material testing technology, specifically to a method and system for measuring the ESR of electrolytic paper in electrolytic capacitors under simulated winding conditions. Background Technology

[0002] The equivalent series resistance (ESR) of aluminum electrolytic capacitors is one of the core parameters determining their electrical performance, operating heat generation, and service life. Electrolytic paper, as a key functional material for absorbing and carrying the electrolyte, directly affects the ESR of the finished capacitor due to its resistive characteristics after being impregnated with the electrolyte. Therefore, accurate measurement of the ESR of electrolytic paper after impregnation with electrolyte is of significant engineering importance for guiding material research and development, optimizing formulation processes, and strengthening product quality control.

[0003] However, in existing technologies, it is usually necessary to manufacture the capacitor before testing its ESR. However, the ESR of the capacitor obtained by this test includes three parts of resistance: the ESR of the oxide film, the ESR of the electrolytic paper + electrolyte (i.e., the ESR of the electrolytic paper after it is wetted with electrolyte), and the ESR of the metal. If the ESR of the electrolytic paper can be accurately known, the temperature rise of the capacitor can be directly calculated through relevant parameters without manufacturing the capacitor. However, there is currently no direct and effective measurement method for the ESR of electrolytic paper after it is wetted with electrolyte in the industry. If the existing laboratory general technology is used to clamp and measure a single layer of electrolytic paper, the following problems exist: (1) Contact resistance interference: The contact resistance generated between the measuring electrode and the surface of the electrolytic paper is often on the order of magnitude of the intrinsic resistance of the electrolytic paper itself, which leads to huge and unstable systematic errors in the measurement results, which seriously restricts the measurement accuracy. (2) Pressure condition distortion: In the actual production line, the electrolytic paper is subjected to a certain tension extrusion during the winding process. This pressure will change the pore structure of the electrolytic paper and the distribution state of the electrolyte, thereby affecting its true resistance characteristics. The simple clamping force applied in traditional measurements cannot truly reproduce the above winding conditions, resulting in a disconnect between the measurement data and the actual working state of the product. (3) Environmental sensitivity issues: The solvent components in the electrolyte are volatile and have a strong hygroscopic effect on moisture in the air. Measurements in an open environment will cause the electrolyte concentration to change continuously, resulting in poor repeatability and low data reliability. (4) Lack of frequency characteristic information: Traditional measurements are usually performed only at a single frequency (such as 100Hz or 1kHz), which cannot reflect the variation of ESR in the actual operating frequency range of the capacitor (such as the wide frequency range of 100Hz to 120kHz commonly used in switching power supplies).

[0004] The frequency dependence of ESR caused by factors such as electrolyte ion polarization effect is key information for evaluating the electrical performance of capacitors in different application scenarios. However, existing technologies in the field of electrolytic paper ESR measurement have systemic defects such as low accuracy, operating condition distortion, large environmental interference, and incomplete information. Therefore, there is an urgent need for a measurement method and system that can overcome the above problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method and system for measuring the ESR of electrolytic paper in electrolytic capacitors under simulated winding conditions. The method and system of this invention can eliminate contact resistance interference, realistically simulate winding pressure conditions, control the stability of the measurement environment, and obtain full-frequency ESR characteristics at different temperatures, achieving high-precision, high-repeatability, and full-frequency precise measurement of the ESR of electrolytic paper after it has been impregnated with electrolyte.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: The first aspect of this invention provides a method for measuring the ESR of electrolytic paper in an electrolytic capacitor under simulated winding conditions, comprising the following steps: S1. Based on the parameters of the target electrolytic capacitor: core winding tension, core diameter, and electrolytic paper width, calculate the equivalent test pressure under actual winding conditions according to the following formula I. Formula I: P = 2T ÷ (W × D); Where P is the equivalent test pressure, in Pascals; T represents the winding tension of the core, in Newtons (N). W is the width of the electrolytic paper, in meters; D is the diameter of the core, in meters. S2. Place the electrolyte-soaked electrolytic paper sample between the electrode components in a sealed environmental chamber, apply the equivalent test pressure obtained in step S1 to the electrode components, maintain the temperature of the electrode components at the preset measurement temperature, and use the multilayer superposition gradient method to measure the total resistance of the multilayer superposition electrolytic paper at multiple frequency points. The multi-layer gradient method is as follows: at a fixed preset measurement temperature, starting from a single layer of the electrolytic paper sample, layers are stacked one by one, with the equivalent test pressure applied to each layer, and multi-point frequency sweep measurement is performed within a preset frequency range, recording the total resistance value at each frequency point. Where n represents the number of stacking layers, and n is an integer greater than or equal to 1; f represents the frequency point; and R... total(n,f ) Indicates the total resistance value; S3. For each frequency point f, with the number of stacking layers n as the independent variable and the total resistance value R... total(n,f) As the dependent variable, based on the following linear model: R total(n) =R contact+ n×R single And the least squares linear regression algorithm is used to process the data point set {n, R}. total(n, f) By fitting the equation, a linearly fitted first-order function equation can be obtained. S4. Data Extraction: The slope of the linear fitting linear function equation is the true ESR value of the single-layer electrolytic paper sample at different frequency points f under a fixed preset measurement temperature, denoted as R. single(f) The intercept of the linearly fitted first-order function equation is the contact resistance that is separated and eliminated at the frequency point f, denoted as R. contact(f) ; S5. Using each frequency point f as the abscissa and its corresponding R... single(f) Using the vertical axis as the ordinate, the ESR-frequency response curve at a fixed preset measurement temperature is plotted. S6. Repeat the above operations S2-S5, and change the preset measurement temperature to obtain the true ESR values ​​of single-layer electrolytic paper samples at different temperatures and frequencies. This can be used to conveniently and quickly evaluate the electrical performance of capacitors in different application scenarios without manufacturing capacitors.

[0007] Equation I is derived as follows: Assume that on the winding machine, the electrolytic paper is wound on the core with a core winding tension T (unit: N), and the core diameter is D and the radius is R; take a very small arc angle on the winding surface and differentiate dθ. Then, on this small arc, the tension at both ends of the electrolytic paper is T. The resultant force generated by tension T, pointing towards the center (radial), is dF. According to the vector composition (two-force composition) method and limit calculus: dF = 2T × sin(dθ ÷ 2). Since dθ is extremely small, sin(dθ ÷ 2) ≈ dθ ÷ 2, so dF ≈ T × dθ. The area of ​​the electrolytic paper corresponding to this tiny arc is equal to the width of the electrolytic paper W × the arc length, and the arc length is equal to R × dθ. According to the definition of pressure, the force P is the resultant force dF divided by the area of ​​the electrolytic paper subjected to the force, then: P=dF÷(W×R×dθ)= T×dθ÷(W×R×dθ)= T÷(W×R)= 2T÷(W×D).

[0008] Furthermore, the goodness of fit R of the linearly fitted linear function equation 2 ≥0.99.

[0009] Preferably, the goodness of fit R of the linearly fitted linear function equation is... 2 ≥0.995.

[0010] Furthermore, the winding tension of the core is 5 Newtons to 18 Newtons.

[0011] Furthermore, the preset frequency mentioned in S2 is in the range of 10 Hz-250 kHz, and the multi-point frequency sweep adopts a logarithmically spaced multi-frequency point sweep method, which is a non-uniform sampling frequency scanning method. Its core feature is that the frequency points are distributed in a logarithmic proportion.

[0012] Furthermore, the preset frequency mentioned in S2 is 100 Hz - 150 kHz.

[0013] Furthermore, the preset measurement temperature in S2 is within the range of -50°C to 200°C. Preferably, the preset measurement temperature in S2 is within the range of 20°C to 120°C.

[0014] A second aspect of the present invention provides a measurement system for implementing the above-described method, comprising an electrode assembly, a test unit, a computer control unit, and an environmental chamber; The electrode assembly is used to place the electrolytic paper sample to be tested. The electrode assembly is located in the environmental chamber. The test unit can transmit the data obtained from testing the electrode assembly to the computer control unit. The computer control unit can control the equivalent test pressure applied to the sample by the electrode assembly and control the electrode assembly. The computer control unit processes the obtained data to obtain the ESR-frequency response curve.

[0015] Furthermore, the electrode assembly includes an upper electrode and a lower electrode, the lower electrode is fixed, and the upper electrode is connected to a pressure application mechanism that moves in the space above the lower electrode; the lower electrode has a built-in heating resistance wire and a temperature sensor (such as PT100) to set and maintain a constant temperature during the measurement process; The test unit is a digital bridge with wideband sweep function (such as an LCR tester). The digital bridge is connected to the electrode assembly through a four-terminal Kelvin test lead to eliminate the influence of the resistance of the connecting wires on the measurement results. The computer control unit is responsible for performing model calculations of equivalent test pressure, controlling the pressure application mechanism to apply pressure to the upper electrode, controlling the measurement temperature of the lower electrode, controlling the sweep frequency parameter settings of the digital bridge and collecting its measurement data, so as to run the linear regression algorithm and data extraction, and finally generating an ESR-frequency response curve report. The environmental chamber provides a well-sealed measurement space with good airtightness for the electrode assembly and the sample to be tested, effectively preventing electrolyte evaporation and external moisture intrusion, ensuring the stability of temperature and humidity in the measurement environment, and ensuring the repeatability and reliability of the data.

[0016] Furthermore, the pressure application mechanism is a pressure actuator driven by a servo motor, and together with a force sensor, it forms a closed-loop pressure control, which can accurately adjust and apply the test pressure based on the calculation results of the equivalent test pressure.

[0017] Furthermore, both the upper electrode and the lower electrode have a conductive, thermally conductive, and electrochemically inert coating on their working surfaces to effectively prevent electrochemical reactions from interfering with the measurement signal; the conductive, thermally conductive, and electrochemically inert coating may be a platinum coating or a graphene coating.

[0018] Beneficial Technical Effects: This invention relates to a measurement system and method for the equivalent series resistance (ESR) and its temperature and frequency characteristics of electrolytic paper after impregnation with electrolyte. It particularly relates to a precision measurement device and automated measurement method that eliminates contact resistance interference through a multi-layer superimposed linear fitting algorithm and simulates actual winding pressure conditions. This invention has outstanding advantages such as high measurement accuracy, realistic working condition reproduction, good data repeatability, and comprehensive frequency characteristics at different temperatures. It is applicable to the research and development of aluminum electrolytic capacitor materials and industrial quality control. This invention completely separates and eliminates the interference of contact resistance from a mathematical perspective by using multi-layer superposition and least squares linear fitting algorithm, so that the true ESR of a single layer of electrolytic paper after being soaked in electrolyte can be accurately extracted, resulting in high measurement accuracy. This invention uses a tension-pressure conversion model (P=2T / (W×D)) to directly convert winding process parameters into a precise and controllable equivalent test pressure P, making the laboratory measurement conditions highly consistent with the actual winding conditions on the production line, restoring the actual working conditions, and significantly improving the guiding value of the measurement results for practical applications. This invention employs the synergistic effect of a sealed environmental chamber and precise temperature control of the lower electrode to effectively eliminate the interference of environmental temperature and humidity fluctuations on the measurement results, ensuring high repeatability and reliability of the data, with good data repeatability. This invention combines wide-band multi-point frequency sweep, which can not only provide ESR values ​​at a single frequency, but also output complete ESR-frequency characteristic curves, providing full-dimensional data support for capacitor material research and development, quality control and engineering selection. This invention combines complex measurement processes and data processing with a standardized and automated testing procedure. It is easy to operate and suitable for large-scale application in the quality control stage of industrial production, and has strong engineering practical value. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the electrolytic capacitor electrolytic paper ESR measurement system for simulating winding conditions according to the present invention. Among them, 1-electrode assembly, 10-electrolytic paper sample, 11-lower electrode, 111-heating resistance wire, 112-temperature sensor, 12-upper electrode, 13-pressure application mechanism, 2-test unit, 21-four-terminal Kelvin test lead, 3-computer control unit, 4-environmental chamber; In the diagram, dashed arrow ① indicates that the computer control unit can control the temperature of the lower electrode; dashed arrow ② indicates that the temperature sensor can feed back the temperature of the lower electrode to the computer control unit and control the temperature; dashed arrow ③ indicates that the computer control unit controls the pressure application mechanism to apply pressure to the upper electrode; dashed arrow ④ indicates that the computer control unit controls the parameter settings of the test unit; and hollow arrow ⑤ indicates that the computer control unit collects data from the test unit. Figure 2 The true ESR value R of the single-layer electrolytic paper after being impregnated with electrolyte, obtained according to the method in Example 3. single(f) ; Figure 3 The values ​​are calculated based on the data in Table 1, showing the ESR values ​​of the single-layer electrolytic paper after being impregnated with electrolyte in the corresponding capacitor model. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0022] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0023] Example 1

[0024] An ESR measurement system for electrolytic capacitor electrolytic paper simulating winding conditions is shown in the diagram below. Figure 1 As shown, It includes electrode assembly 1, test unit 2, computer control unit 3, and environmental chamber 4; The electrode assembly 1 is used to place the electrolytic paper sample 10 to be tested. The electrode assembly 1 is located in the environmental chamber 4. The test unit 2 can transmit the data obtained from the test of the electrode assembly 1 to the computer control unit 3. The computer control unit 3 can control the equivalent test pressure applied to the sample by the electrode assembly 1 and control the electrode assembly 1. The computer control unit 3 processes the obtained data to obtain the ESR-frequency characteristic curve. Specifically, the electrode assembly 1 includes an upper electrode 12 and a lower electrode 11. The lower electrode 11 is fixed, and the upper electrode 12 is connected to a pressure application mechanism 13 that moves in the space above the lower electrode 11. The lower electrode 11 has a built-in heating resistance wire 111 and a temperature sensor 112, which are used to set and maintain a constant temperature during the measurement process. The test unit 2 is a digital bridge with wideband sweep function (such as HIOKI IM3536, frequency range 4Hz~8MHz), and the digital bridge is connected to the electrode assembly 1 through four-terminal Kelvin test leads 21. The computer control unit 3 is responsible for performing model calculations of equivalent test pressure, controlling the pressure application mechanism 13 to apply pressure to the upper electrode 12, controlling the preset measurement temperature of the lower electrode 11 (i.e., reading the temperature feedback value of the temperature sensor 112 in real time by controlling the temperature of the heating resistance wire 111), controlling the sweep frequency parameter setting of the digital bridge and collecting its measurement data. For example, the computer control unit 3 communicates with the measurement unit 2 through a data transmission line (GPIB or USB interface) to run the linear regression algorithm and data extraction, and finally generate an ESR-frequency characteristic curve report. The environmental chamber 4 provides a closed measurement space for the electrode assembly 1 and the electrolytic paper sample 10 to be tested; The pressure application mechanism 13 is a pressure actuator driven by a servo motor, and together with a force sensor, it forms a closed-loop pressure control (such as a servo motor + a 300N range force sensor), which can accurately adjust and apply the test pressure based on the calculation results of the equivalent test pressure. The working surfaces of both the upper electrode 12 and the lower electrode 11 are provided with a conductive, thermally conductive, and electrochemically inert coating; the conductive, thermally conductive, and electrochemically inert coating is a platinum-plated coating or a graphene coating.

[0025] Example 2

[0026] A method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions includes the following steps: S1. Based on the parameters of the target electrolytic capacitor: core winding tension, core diameter, and electrolytic paper width, calculate the equivalent test pressure under actual winding conditions according to the following formula I. Formula I: P = 2T ÷ (W × D), where P is the equivalent test pressure, T is the winding tension of the core, W is the width of the electrolytic paper, and D is the diameter of the core; S2. Place the electrolyte-soaked electrolytic paper sample between the electrode components in a sealed environmental chamber, apply the equivalent test pressure obtained in step S1 to the electrode components, maintain the temperature of the electrode components at the preset measurement temperature, and use the multilayer superposition gradient method to measure the total resistance of the multilayer superposition electrolytic paper at multiple frequency points. The multi-layer gradient method is as follows: at a fixed preset measurement temperature, starting from a single layer of the electrolytic paper sample, layers are stacked one by one, with the equivalent test pressure applied to each layer, and multi-point frequency sweep measurement is performed within a preset frequency range, recording the total resistance value at each frequency point. Where n represents the number of stacking layers, and n is an integer greater than or equal to 1; f represents the frequency point; and R... total(n,f ) Indicates the total resistance value; S3. For each frequency point f, with the number of stacking layers n as the independent variable and the total resistance value R... total(n, f) As the dependent variable, based on the following linear model: R total(n) =R contact + n×R single And the least squares linear regression algorithm is used to process the data point set {n, R}. total(n, f) By fitting the equation, a linearly fitted first-order function equation can be obtained. S4. Data Extraction: The slope of the linear fitting linear function equation is the true ESR value of the single-layer electrolytic paper sample at different frequency points f under a fixed preset measurement temperature, denoted as R. single(f) The intercept of the linearly fitted first-order function equation is the contact resistance that is separated and eliminated at the frequency point f, denoted as R. contact(f) ; S5. Using each frequency point f as the abscissa and its corresponding R... single(f) Using the vertical axis as the ordinate, the ESR-frequency response curve at a fixed preset measurement temperature is plotted. S6. Repeat the above operations S2-S5, and change the preset measurement temperature to obtain the true ESR values ​​of single-layer electrolytic paper samples at different temperatures and frequencies. This can be used to conveniently and quickly evaluate the electrical performance of capacitors in different application scenarios without manufacturing capacitors.

[0027] Example 3

[0028] The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions, based on the measurement system of Example 1 and the measurement method of Example 2, includes the following steps: S1-Step 1, Parameter Input: Input the following process parameters into the software interface of the computer control unit: preset measurement temperature Temp=20℃, core winding tension T=5N, electrolytic paper width W=0.04m (40mm), core diameter D=0.006m (6mm), maximum number of electrolytic paper layers n=5; sweep frequency range is 10Hz~40kHz, with 17 frequency points at logarithmic intervals.

[0029] S1-Step2, Pressure Calculation: The computer control unit automatically calculates the equivalent test pressure P according to the built-in formula P=2T÷(W×D). According to the parameters in Step1, P=(2×5)÷(0.04×0.006)≈41667Pa (approximately 42kPa). The computer control unit instructs the pressure application mechanism to adjust the upper electrode to the standby position and lock the target pressure value.

[0030] S2-Step1, System Preheating: Start the heating resistance wire of the lower electrode, and the computer control unit controls the heating power to maintain the temperature of the lower electrode at 20℃ and stabilize it (fluctuation within ±0.5℃). The preheating time is about 15 minutes.

[0031] S2-Step2, Sample Preparation: Cut 5 pieces of the electrolytic paper sample to be tested into standard size of 30mm×30mm, immerse them in the target electrolyte (such as ethylene glycol system electrolyte) for 5 minutes until fully saturated, remove them and gently press with lint-free paper to absorb excess liquid from the surface.

[0032] S2-Step3, First layer sample placement: Open the environmental chamber, place the first prepared electrolytic paper sample in the center of the lower electrode, close the chamber cover, and let it stand for 5 minutes to allow the sample temperature to reach the same temperature as the electrode. Level 1 Measurement: The computer control unit instructs the upper electrode to descend, the force sensor provides real-time feedback, and the servo motor-driven pressure actuator adjusts to apply a constant pressure P=42kPa. The automatic measurement program of the test unit is then initiated. The test unit performs a logarithmic frequency sweep from 10Hz to 40kHz, measuring and recording the total resistance R at 17 frequency points f. total(n=1, f) After the measurement is completed, the upper electrode is raised to the standby position; Measurement of Layers 2-5: Open the environmental chamber lid and stack the 2nd to 5th electrolytic papers on top of the previous layer in sequence. After each stacking, close the chamber, apply pressure, and scan the frequency, recording the R values ​​respectively. total(n=2, f) To R total(n=5, f) .

[0033] S3. Linear Fitting: After the measurement cycle is completed, the computer control unit performs linear fitting for each frequency point f, using the number of superimposed layers n (n=1,2,3,4,5) as the independent variable and the total resistance value R. total(n,f) As the dependent variable, based on the following linear model: R total(n) =R contact + n×R single And the least squares linear regression algorithm is used to process the data point set {n, R}. total(n,f) The system is fitted to obtain a linear function equation, and the fit degree R² is calculated. The R² values ​​of all frequency points are checked. If R² < 0.99 at a certain frequency point, the data point is marked as "abnormal" in the report, and the operator is prompted to check the sample preparation quality. S4. Data Extraction: The slope of the linearly fitted linear function equation is the true ESR value R of the single-layer electrolytic paper sample at 20℃ and various frequency points f. single(f) The intercept of the linearly fitted linear function equation is the contact resistance R that is separated and eliminated at the frequency point f. contact(f) ; S5. Result Output: The computer control unit software uses frequency f (Hz) as the horizontal axis and R as the vertical axis. single(f) (Ω) is used as the vertical axis, and the ESR-frequency response curve at 20℃ is displayed on the screen.

[0034] S6. Set the lower electrode temperature to be maintained at 25℃, 30℃, 40℃, 60℃, 85℃, and 105℃ and stabilized. Repeat the above steps S2-S5 at each preset measurement temperature to obtain the ESR-frequency characteristic curves at different temperatures. Simultaneously, generate a data set including the original data, fitting parameters, R² value, and contact resistance R. contact(f) It provides complete data reports containing information such as CSV and PDF, and supports exporting to CSV or PDF formats.

[0035] Example 4

[0036] Electrolytic paper (density 0.6 g / cm³) for a certain batch of 400V 560μF 30×45 type aluminum electrolytic capacitors. 3 The sample of a single-layer electrolytic paper (60 mm × 30 mm thick, made of wood pulp fiber) was used as the test object. The electrolyte used was an ethylene glycol system electrolyte (conductivity 1500 μS / cm). The measurement was performed according to the steps in Example 3. The slope extracted from S4 was the true ESR value R of the single-layer electrolytic paper after being impregnated with the electrolyte. single(f) Specific data are shown in Table 1 and Figure 2 ,right Figure 2By fitting the data at each point in the table, we can obtain the ESR-frequency characteristic curves of the single-layer electrolytic paper sample at various temperatures after it has been immersed in the electrolyte. Converting the data in Table 1 to the size of the electrolytic paper in the entire capacitor (35mm × 1800mm) according to the projected area, the ESR values ​​of the electrolytic paper after immersion in the electrolyte in the capacitor are shown in Table 2 and... Figure 3 ,right Figure 3 By fitting the data at various points, the ESR-frequency response curves of the electrolytic paper immersed in the electrolyte in the capacitor can be obtained at various temperatures. Measurements were repeated three times for the same batch of samples. Table 1 shows the ESR (i.e., RV) at each frequency point and temperature. single The relative standard deviation (RSD) of the values ​​is less than 1.5%, indicating that the measurement method of the present invention has excellent repeatability and data stability.

[0037] The data is shown in Table 1.

[0038] Table 1. ESR (R) of single-layer electrolytic paper samples after impregnation with electrolyte. single )data

[0039] Table 2 shows the ESR values ​​of the electrolytic paper after immersion in the electrolyte in the capacitor, calculated based on the data in Table 1.

[0040] This invention provides a direct and effective method for measuring the ESR of electrolyte-impregnated electrolytic paper. The method and system fill a gap in the industry by simulating actual winding pressure conditions. Through multi-layer superposition and linear fitting of electrolyte-impregnated electrolytic paper, the interference of contact resistance is completely separated and eliminated from a mathematical perspective. This allows for the precise extraction of the true ESR characteristics of single-layer electrolytic paper at different temperatures and across the entire frequency band. This achieves high-precision, high-repeatability, and full-frequency band precision measurement of the ESR of electrolyte-impregnated electrolytic paper. It can be used to conveniently and quickly evaluate the temperature rise performance of capacitors at different temperatures and frequencies without manufacturing capacitors (capacitor temperature rise = heat generation × capacitor thermal resistance, and heat generation = ripple current squared × ESR). It has good parameter guidance significance and strong engineering practical value.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for measuring the ESR of electrolytic paper in electrolytic capacitors under simulated winding conditions, characterized in that, Includes the following steps: S1. Based on the parameters of the target electrolytic capacitor: core winding tension, core diameter, and electrolytic paper width, calculate the equivalent test pressure under actual winding conditions according to the following formula I. Formula I: P = 2T ÷ (W × D); Where P is the equivalent test pressure, in Pascals; T represents the winding tension of the core, in Newtons (N). W is the width of the electrolytic paper, in meters; D is the diameter of the core, in meters. S2. Place the electrolyte-soaked electrolytic paper sample between the electrode components in a sealed environmental chamber, apply the equivalent test pressure obtained in step S1 to the electrode components, maintain the temperature of the electrode components at the preset measurement temperature, and use the multilayer superposition gradient method to measure the total resistance of the multilayer superposition electrolytic paper at multiple frequency points. The multi-layer gradient method is as follows: at a fixed preset measurement temperature, starting from a single layer of the electrolytic paper sample, layers are stacked one by one, with the equivalent test pressure applied to each layer, and multi-point frequency sweep measurement is performed within a preset frequency range, recording the total resistance value at each frequency point. Where n represents the number of stacking layers, and n is an integer greater than or equal to 1; f represents the frequency point; and R... total(n,f) Indicates the total resistance value; S3. For each frequency point f, with the number of stacking layers n as the independent variable and the total resistance value R... total(n, f) As the dependent variable, based on the following linear model: R total(n) =R contact + n×R single And the least squares linear regression algorithm is used to process the data point set {n, R}. total(n, f) By fitting the equation, a linearly fitted first-order function equation can be obtained. S4. Data Extraction: The slope of the linear fitting linear function equation is the true ESR value of the single-layer electrolytic paper sample at different frequency points f under a fixed preset measurement temperature, denoted as R. single(f) The intercept of the linearly fitted first-order function equation is the contact resistance that is separated and eliminated at the frequency point f, denoted as R. contact(f) ; S5. Using each frequency point f as the abscissa and its corresponding R... single(f) Using the vertical axis as the ordinate, the ESR-frequency response curve at a fixed preset measurement temperature is plotted. S6. Repeat the above operations S2-S5, and change the preset measurement temperature to obtain the true ESR values ​​of single-layer electrolytic paper samples at different temperatures and frequencies. This can be used to conveniently and quickly evaluate the electrical performance of capacitors in different application scenarios without manufacturing capacitors.

2. The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions according to claim 1, characterized in that, The goodness of fit R of the linearly fitted linear function equation 2 ≥0.

99.

3. The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions according to claim 1, characterized in that, The winding tension of the core is 5 N to 18 N.

4. The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions according to any one of claims 1-3, characterized in that, The preset frequency mentioned in S2 is in the range of 10 Hz-250 kHz; the multi-point frequency sweep adopts a logarithmically spaced multi-frequency point sweep method.

5. The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions according to claim 4, characterized in that, The preset frequency mentioned in S2 is 100 Hz - 150 kHz.

6. The method for measuring the ESR of electrolytic capacitor electrolytic paper under simulated winding conditions according to any one of claims 1-3, characterized in that, The preset measurement temperature in S2 is within the range of -50℃ to 200℃.

7. An electrolytic capacitor electrolytic paper ESR measurement system simulating winding conditions, characterized in that, Used to implement the measurement method as described in any one of claims 1-6; It includes an electrode assembly (1), a test unit (2), a computer control unit (3), and an environmental chamber (4); The electrode assembly (1) is used to place the electrolytic paper sample (10) to be tested. The electrode assembly (1) is located in the environmental chamber (4). The test unit (2) can transmit the data obtained from the test of the electrode assembly (1) to the computer control unit (3). The computer control unit (3) can control the equivalent test pressure applied by the electrode assembly (1) to the sample and control the electrode assembly (1). The computer control unit (3) organizes the obtained data to obtain the ESR-frequency characteristic curve.

8. The electrolytic capacitor electrolytic paper ESR measurement system for simulating winding conditions according to claim 7, characterized in that, The electrode assembly (1) includes an upper electrode (12) and a lower electrode (11). The lower electrode (11) is fixed, and the upper electrode (12) is connected to a pressure application mechanism (13) that moves in the space above the lower electrode (11). The lower electrode (11) has a built-in heating resistance wire (111) and a temperature sensor (112) for setting and maintaining a constant temperature during the measurement process. The test unit (2) is a digital bridge with wideband sweep frequency function. The digital bridge is connected to the electrode assembly (1) through a four-terminal Kelvin test line (21). The computer control unit (3) is responsible for performing model calculation of equivalent test pressure, controlling the pressure application mechanism (13) to apply pressure to the upper electrode (12), controlling the measurement temperature of the lower electrode (11), controlling the sweep frequency parameter setting of the digital bridge and collecting its measurement data, so as to run the linear regression algorithm and data extraction, and finally generate an ESR-frequency characteristic curve report. The environmental chamber (4) provides a closed measurement space for the electrode assembly (1) and the electrolytic paper sample (10) to be tested.

9. The electrolytic capacitor electrolytic paper ESR measurement system for simulating winding conditions according to claim 8, characterized in that, The pressure application mechanism (13) is a pressure actuator driven by a servo motor, and together with a force sensor, it forms a closed-loop pressure control.

10. The electrolytic capacitor electrolytic paper ESR measurement system for simulating winding conditions according to claim 8, characterized in that, The working surfaces of the upper electrode (12) and the lower electrode (11) are provided with a conductive, thermally conductive and electrochemically inert coating; the conductive, thermally conductive and electrochemically inert coating is a platinum coating or a graphene coating.

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