Analysis method, system and equipment for equivalent series resistance of capacitor and storage medium

Abstract

The invention relates to the technical field of power equipment, and discloses a capacitor equivalent series resistance (ESR) analysis method, system and device and a storage medium, and the method comprises the steps: building a broadband distributed equivalent model of a capacitor, adjusting the parameter value of at least one influence factor in the broadband distributed equivalent model, and obtaining the ESR value of the capacitor; the broadband distributed equivalent model is tested when the influence factors correspond to different parameter values, multiple test data are obtained through the broadband distributed equivalent model, analysis is carried out according to the multiple test data, and the influence of each influence factor on the equivalent series resistance ESR in the capacitor is determined. According to the technical scheme provided by the invention, test analysis is carried out by adopting different voltage frequencies, so that the relationship between different influence factors and the ESR can be determined under unstable working conditions such as harmonic voltage and transient voltage, the design of the capacitor can be optimized, energy loss and heating can be reduced, and the service life of the capacitor can be prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment, and in particular to an analysis method, system, equipment and storage medium for equivalent series resistance (ESR) of a capacitor. Background Art

[0002] Frequency-converter capacitors will experience losses during operation, which may increase the operating temperature of the frequency-converter capacitors, reduce the electrical and mechanical properties of the frequency-converter capacitors, and may further damage the frequency-converter capacitors. Therefore, the ESR that causes the losses can be monitored and analyzed to determine the relationship between ESR and the losses of the frequency-converter capacitors.

[0003] In the related technology, ESR can be monitored by online monitoring technology. During the normal operation of the frequency-variable capacitor, the circuit parameters of the frequency-variable capacitor are collected by online monitoring technology, so that the relationship between the frequency-variable capacitor and each circuit parameter can be determined based on the collected circuit parameters.

[0004] However, online monitoring technology usually collects current at a fixed frequency. In actual applications, for harmonic voltage, the circuit parameters of the frequency-variable capacitor cannot be accurately obtained through online monitoring technology, and thus the relationship between the capacitor and various circuit parameters cannot be accurately determined. Summary of the invention

[0005] Based on this, in order to solve the problem that the circuit parameters of the capacitor cannot be accurately obtained through the existing online monitoring technology, and thus the relationship between the capacitor and various circuit parameters cannot be accurately determined, an analysis method, system, equipment and storage medium for the equivalent series resistance (ESR) of the capacitor are proposed.

[0006] In a first aspect, a method for analyzing equivalent series resistance of a capacitor is provided, which is applied to an analysis system for equivalent series resistance of a capacitor, and the method comprises:

[0007] Establish a broadband distributed equivalent model of capacitors;

[0008] Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance;

[0009] Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when each of the influencing factors corresponds to a different parameter value;

[0010] An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

[0011] Optionally, analyzing the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance ESR in the capacitor includes:

[0012] Determine, according to the type corresponding to each of the test data, a change trend corresponding to each type of the test data;

[0013] According to the change trend of each type of the test data, the influence of each influencing factor on the ESR is determined.

[0014] Optionally, determining, according to the type corresponding to each type of the test data, a change trend corresponding to each type of the test data includes:

[0015] Classifying the plurality of test data according to the type corresponding to each of the test data to obtain multiple categories of test data;

[0016] For each type of the test data, the change trend corresponding to each type of the test data is obtained according to different parameter values ​​corresponding to each of the influencing factors.

[0017] Optionally, determining the influence of each influencing factor on the ESR according to the change trend of each type of the test data includes:

[0018] Determine, according to the change trend of each type of the test data, the change amount of each type of the test data based on different parameter values ​​corresponding to each of the influencing factors;

[0019] The influence of each of the influencing factors on the ESR is determined according to the change amount and in combination with a preset change threshold.

[0020] Optionally, determining the influence of each of the influencing factors on the ESR according to the change amount in combination with a preset change threshold value includes:

[0021] For each of the influencing factors, determining the influence trend between the influencing factor and the ESR according to the positive and negative relationship of the change amount;

[0022] The influence degree between the influencing factor and the ESR is determined according to the magnitude relationship between the absolute value of the change amount and the change threshold.

[0023] Optionally, before analyzing the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance (ESR) of the capacitor, the method further includes:

[0024] Based on different parameter values ​​corresponding to voltage and frequency respectively, at least one of a current phase error, a current amplitude error and an ESR error is obtained through the broadband distributed equivalent model, wherein the voltage frequency is a frequency corresponding to a voltage input into the broadband distributed equivalent model;

[0025] According to at least one of the current phase error, the current amplitude error and the ESR error, the equivalent capacitance, the equivalent inductance and the equivalent resistance are screened to obtain an effective ESR;

[0026] The analyzing according to the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance (ESR) in the capacitor includes:

[0027] An analysis is performed based on the plurality of test data to determine the influence of the influencing factors on the effective ESR.

[0028] Optionally, the test data includes: inlet current amplitude, inlet current phase, at least one of the equivalent resistance and the equivalent capacitance

[0029] In a second aspect, a capacitor equivalent series resistance analysis system is provided, the capacitor equivalent series resistance analysis system comprising: a power supply, an oscilloscope and a current transformer;

[0030] The capacitor is connected to the power supply, the oscilloscope is connected to the first electrode of the capacitor through a probe, and the oscilloscope is connected to the second electrode of the capacitor through the current transformer.

[0031] According to a third aspect, a computer-readable storage medium is provided, storing a computer program, wherein when the computer program is executed by a processor, the processor performs the following steps:

[0032] Establish a broadband distributed equivalent model of capacitors;

[0033] Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance;

[0034] Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when the parameters to be tested correspond to different parameter values ​​respectively;

[0035] An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

[0036] In a fourth aspect, an analysis device is provided, characterized in that the analysis device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0037] Establish a broadband distributed equivalent model of capacitors;

[0038] Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance;

[0039] Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when the parameters to be tested correspond to different parameter values ​​respectively;

[0040] An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

[0041] In summary, the present application provides an analysis method for equivalent series resistance of a capacitor, by establishing a broadband distributed equivalent model of the capacitor, and adjusting the parameter value of at least one influencing factor in the broadband distributed equivalent model, so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, and then a plurality of test data are obtained through the broadband distributed equivalent model, and finally, the influence of each influencing factor on the equivalent series resistance ESR in the capacitor is determined according to the analysis of the plurality of test data. By determining the influence of each influencing factor on ESR, the influence of the voltage and current distribution inside the capacitor on the capacitor loss can be determined, and by using different voltage frequencies for testing and analysis, the relationship between different influencing factors and ESR can be determined for unstable working conditions such as harmonic voltage and transient voltage, which helps to optimize the design of the capacitor, reduce energy loss and heat generation, and extend the service life of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] in:

[0044] Figure 1 A system schematic diagram of a capacitor equivalent series resistance analysis system involved in a capacitor equivalent series resistance analysis method provided in an embodiment of the present application;

[0045] Figure 2 A schematic flow chart of a method for analyzing equivalent series resistance of a capacitor provided in an embodiment of the present application;

[0046] Figure 3 A circuit diagram of a capacitor ESR provided in an embodiment of the present application;

[0047] Figure 4 A schematic flow chart of determining the influence of an influencing factor on ESR provided in an embodiment of the present application;

[0048] Figure 5A A schematic diagram of the corresponding relationship between a voltage frequency and an inlet current amplitude provided in an embodiment of the present application;

[0049] Figure 5B A schematic diagram of the corresponding relationship between a voltage frequency and an inlet current phase provided in an embodiment of the present application;

[0050] Figure 5C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance provided in an embodiment of the present application;

[0051] Figure 5D A schematic diagram of the corresponding relationship between voltage frequency and equivalent capacitance provided in an embodiment of the present application;

[0052] Figure 5E A schematic diagram of an inlet current variation curve provided in an embodiment of the present application;

[0053] Fig. 6A A schematic diagram of the corresponding relationship between voltage frequency and inlet current amplitude based on different electrode plate lengths provided in an embodiment of the present application;

[0054] Figure 6B A schematic diagram of the corresponding relationship between voltage frequency and inlet current phase based on different electrode plate lengths provided in an embodiment of the present application;

[0055] Figure 6C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance based on different electrode lengths provided in an embodiment of the present application;

[0056] Fig.6D A schematic diagram of the corresponding relationship between voltage frequency and equivalent capacitance based on different electrode lengths provided in an embodiment of the present application;

[0057] Fig. 7A A schematic diagram of the corresponding relationship between voltage frequency and inlet current amplitude based on different plate resistances provided in an embodiment of the present application;

[0058] Figure 7B A schematic diagram of the corresponding relationship between voltage frequency and inlet current phase based on different plate resistances provided in an embodiment of the present application;

[0059] Figure 7C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance based on different plate resistances provided in an embodiment of the present application;

[0060] Fig. 8A A schematic diagram of a change trend of an inlet current phase and an inlet current amplitude of a capacitor under different voltage frequencies provided in an embodiment of the present application;

[0061] Figure 8B A schematic diagram of a change trend of equivalent resistance and equivalent capacitance of a capacitor under different voltage frequencies provided in an embodiment of the present application;

[0062] Figure 8C A schematic diagram of the change trend of ESR of capacitors with different capacitances under different voltage frequencies provided in an embodiment of the present application;

[0063] Fig. 9 This is a diagram of the internal structure of an analysis device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The active power loss of capacitors plays a key role in the temperature and dielectric aging of capacitors, which also affects the insulation state of capacitors. Capacitor equipment has dielectric loss and conductor loss. Harmonics, resonant voltage, overvoltage, etc. will cause the effective value of the equipment's working current to increase, resulting in increased active power loss and increased equipment temperature, which will cause equipment overheating failure. After the capacitor is put into operation, the metal loss generated remains basically unchanged, while the dielectric loss will have a decline process in the initial stage, which is closely related to the operating state of the capacitor.

[0066] In the actual operation of capacitors, periodic high-frequency voltage components significantly enhance their insulation dielectric loss, the main losses include dielectric loss, internal fuse loss, wire and plate loss. Harmonic voltages increase and unevenly distribute current, aggravate plate loss, and cause temperature rise, affecting the insulation state of capacitors. In severe cases, it may cause equipment damage.

[0067] Existing studies either use a single RC model to ignore the broadband response, or consider the plate current to be linearly distributed, ignoring the impact of the voltage and current distribution inside the capacitor on the loss. Therefore, it is necessary to establish a distributed broadband equivalent model under broadband voltage to accurately analyze the loss. Among them, the RC model is a circuit model used to describe the impact of resistance and capacitance on current and voltage in the circuit. The RC model consists of a resistor (R) and a capacitor (C) in series or in parallel, and is used to simulate the energy storage and loss process in the circuit.

[0068] At present, scholars at home and abroad have proposed some capacitor ESR state monitoring technologies, which are mainly divided into two categories: offline monitoring and online monitoring. Offline monitoring technology can only monitor capacitor ESR when the system is shut down, ignoring the impact of actual working conditions and load conditions on capacitor ESR. Online monitoring technology monitors capacitor parameters in real time during normal system operation, which can reflect the parameter changes of capacitors in actual working conditions and is more in line with actual needs. The inductor, capacitor, and resistor LCR digital bridge is often used to measure the ESR of capacitors. However, the excitation current of the LCR digital bridge is generally less than 100mA fixed frequency current during measurement, and capacitors often work in complex working conditions of harmonic voltage and transient voltage. The current flowing through the capacitor will also have high amplitude and high frequency. Different working conditions will cause the ESR value of the capacitor to change nonlinearly with the current size. Among them, the LCR digital bridge is mainly used to measure the parameters of inductance (L), capacitance (C) and resistance (R). It is an instrument that can accurately measure the performance of these electrical components.

[0069] Therefore, the embodiment of the present application proposes a method for analyzing the equivalent series resistance of a capacitor, by establishing a broadband distributed equivalent model of the capacitor, and adjusting the parameter value of at least one influencing factor in the broadband distributed equivalent model, so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, and then a plurality of test data are obtained through the broadband distributed equivalent model, and finally, the influence of each influencing factor on the equivalent series resistance ESR in the capacitor is determined based on the analysis of the plurality of test data. By determining the influence of each influencing factor on the ESR, the influence of the voltage and current distribution inside the capacitor on the capacitor loss can be determined, and by using different voltage frequencies for testing and analysis, the relationship between different influencing factors and ESR can be determined for unstable working conditions such as harmonic voltage and transient voltage, which helps to optimize the design of the capacitor, reduce energy loss and heat generation, and extend the service life of the capacitor.

[0070] Figure 1 A schematic diagram of a system for analyzing the equivalent series resistance of a capacitor involved in the analysis method for the equivalent series resistance of a capacitor provided in an embodiment of the present application. Figure 1 The capacitor equivalent series resistance analysis system includes: a power supply 110, an oscilloscope 120 and a current transformer 130.

[0071] The capacitor 140 may be connected to the power supply 110 , the oscilloscope 120 may be connected to the first electrode of the capacitor 140 via a probe, and the oscilloscope 120 may also be connected to the second electrode of the capacitor 140 via a current transformer 130 .

[0072] Specifically, the power supply 110 can supply power to the capacitor 140, and the current transformer 130 can collect multiple test data such as the current and voltage of the capacitor 140 in real time. Moreover, during the power supply process, the power supply 110 can also adjust multiple parameters such as the voltage, current, and voltage frequency input to the capacitor 140 according to the triggered operation, so that the input voltage, current, and voltage frequency and other parameters are used as influencing factors for testing.

[0073] Accordingly, after collecting a plurality of test data, the influence of each influencing factor on the capacitor ESR can be determined based on the plurality of test data and in combination with the constantly changing influencing factors, that is, the distribution of voltage and current in the capacitor and the influence on the capacitor ESR are analyzed.

[0074] It should be noted that in practical applications, the inlet current and ESR can be measured by applying harmonic voltage to the metal film capacitor to analyze the working state of the capacitor. For example, the experiment can use an oil-immersed explosion-proof capacitor, which uses a metallized zinc-aluminum film with thickened edges as electrodes and dielectrics, and is wound and loaded into an aluminum casing. The sesame oil injected into the casing can isolate the equipment from the air while improving its tolerance to high temperatures. The available capacitance of this capacitor ranges from 5μF to 75μF, the operating voltage is 450 volts (V) (direct current (AC)), and the operating frequency is 50 hertz (Hz).

[0075] Moreover, a variable frequency power supply can be used. The variable frequency power supply can output a 40-1000Hz adjustable, 0-300V adjustable sinusoidal voltage waveform by using an insulated gate bipolar transistor (IGBT) / sine pulse width modulation (SPWM) pulse width modulation method. It adopts a three-phase input and a unidirectional output mode. The output capacity is 20 kilovolt-amperes (kVA), the maximum current at a low level is 166.6 amperes (A) (0-150V), the maximum current at a high level is 83.3A (150-300V), and the frequency stability rate error is ≤0.01%.

[0076] In addition, the inlet current flowing through the capacitor is measured by a current sensor. The current frequency ratio of the current transformer is 0.006, which can still ensure high accuracy when measuring high-frequency and large currents.

[0077] Figure 2 A schematic flow chart of a method for analyzing equivalent series resistance of a capacitor provided in an embodiment of the present application, such as Figure 2 As shown, an embodiment of the present application provides a method for analyzing equivalent series resistance of a capacitor, which can be applied to the above-mentioned analysis system of equivalent series resistance of a capacitor. The method for analyzing equivalent series resistance of a capacitor specifically includes the following steps:

[0078] S1. Establish a broadband distributed equivalent model of capacitors.

[0079] Among them, the broadband distributed equivalent model is an equivalent model corresponding to the capacitor. The broadband distributed equivalent model may include equivalent capacitance, equivalent inductance and equivalent resistance connected in series, and the electronic components with impedance in the capacitor are simulated by the equivalent capacitance, equivalent inductance and equivalent resistance.

[0080] In order to determine the impact of the ESR of the capacitor and the inlet current of the capacitor, a broadband distributed equivalent model of the capacitor can be constructed. The current signal (such as current amplitude and current phase) in the broadband distributed equivalent model of the capacitor is collected, and then the electrical parameters corresponding to other electronic components in the broadband distributed equivalent model of the capacitor are combined to complete the analysis of the ESR.

[0081] Here, the inlet current is the current of the input ESR.

[0082] For example, Figure 3 A circuit diagram of a capacitor ESR provided in an embodiment of the present application, such as Figure 3 As shown, ESR can include: equivalent capacitance C s And the equivalent resistance R s , the input voltage across the ESR is U0, and the input current into the ESR is i.

[0083] S2. Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values.

[0084] The influencing factors include: at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance, and the voltage frequency is the frequency corresponding to the voltage input into the broadband distributed equivalent model.

[0085] After constructing the broadband distributed equivalent model, the current or voltage output by the power supply in the analysis system can be adjusted by adjusting the capacitor equivalent series resistance, or the capacitor can be replaced so that different capacitors can operate in different circuit environments. In the subsequent steps, data can be collected based on the broadband distributed equivalent model operating in different circuit environments to complete the analysis of ESR.

[0086] For example, the output current phase, current amplitude or voltage frequency can be adjusted by the power supply, or the capacitor plate length, capacitor plate resistance or capacitor capacitance can be adjusted by manual operation or simulation to adjust the capacitor parameters. The embodiment of the present application does not specifically limit the method of adjusting the influencing factors.

[0087] S3. Obtain multiple test data through a broadband distributed equivalent model.

[0088] Among them, a plurality of test data are obtained for the broadband distributed equivalent model when each influencing factor corresponds to different parameter values.

[0089] Specifically, the broadband distributed equivalent model can work based on the current of the power supply input, and collect the inlet current through the current transformer to obtain test data such as the inlet current amplitude and the inlet current phase. It can also calculate based on the voltage provided by the power supply, that is, the input voltage across the ESR, combined with the inlet current to obtain test data such as the equivalent resistance and equivalent capacitance of the ESR.

[0090] Correspondingly, after the test of a certain parameter value of a certain influencing factor is completed, the parameter value of the influencing shadow can be adjusted, and multiple test data can be recorded again, and the above process of adjusting the parameter value and recording the test data can be repeated. If the test data corresponding to the parameter value of a certain influencing factor has been recorded, the parameter value of the next influencing factor can be adjusted until the test data corresponding to each parameter value of each influencing factor has been recorded.

[0091] It should be noted that in actual applications, the number of parameter values ​​corresponding to each influencing factor can be set according to the accuracy of the power supply, and can also be adjusted according to the specifications of the capacitor. The embodiment of the present application does not specifically limit the number of parameter values ​​of each influencing factor.

[0092] In addition, in order to improve the efficiency of ESR analysis, each data in the ESR may be screened to determine the effective ESR before analyzing the test data. That is, after executing step S3, steps S4 and S5 may be executed.

[0093] However, according to actual applications, the data included in the ESR can be analyzed. Then, after executing step S3, step S6 can be executed without executing step S4 and step S5. The embodiment of the present application does not specifically limit whether to execute steps S4 and S5.

[0094] S4. Based on different parameter values ​​corresponding to the voltage frequency, at least one of the current phase error, the current amplitude error and the ESR error is obtained through a wide-band distributed equivalent model.

[0095] Among them, ESR can include: equivalent capacitance, equivalent inductance and equivalent resistance.

[0096] Accordingly, tests can be performed based on different voltage frequencies to obtain at least one of the current phase error, current amplitude error and ESR error output by the wide-band distributed equivalent model at different voltage frequencies, so that in subsequent steps, the effective ESR can be determined by comparing at least one parameter.

[0097] It should be noted that the embodiment of the present application uses voltage frequency as a variable to test various ESR data, and in actual applications, other influencing shadows can also be tested as variables, and the embodiment of the present application does not make specific limitations on this.

[0098] S5. Screen the equivalent capacitance, the equivalent inductance, and the equivalent resistance according to at least one of the current phase error, the current amplitude error, and the ESR error to obtain an effective ESR.

[0099] Corresponding to S4, after obtaining at least one test data of the current phase error, the current amplitude error and the ESR error, the error corresponding to each data in the ESR can be determined by comparison based on the test data, so that the effective ESR can be determined.

[0100] For example, as shown in Table 1, Table 1 is an error comparison table of a capacitor with or without plate inductance provided in an embodiment of the present application, which respectively shows the absolute errors and relative errors corresponding to the current phase error, current amplitude error and ESR error at different voltage frequencies, so that the equivalent capacitance, equivalent inductance and equivalent resistance in the ESR can be screened according to the absolute errors and relative errors.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, the capacitors with or without plate inductance have an impact on the calculation of inlet current phase, inlet current amplitude and ESR, but the data is compared with the data calculated without considering the plate inductance, and the absolute error between the two values ​​is extremely low. Even at 20,000 Hz, the relative error is less than 0.0001%. Therefore, in the analysis of the capacitor ESR, it can be considered that the data reflecting the online working state of the capacitor is mainly related to the equivalent capacitance and equivalent resistance, and the ESR can be screened, so that it can be determined that the effective ESR can include the equivalent capacitance and equivalent resistance.

[0104] S6. Analyze multiple test data to determine the impact of each influencing factor on the equivalent series resistance (ESR) in the capacitor.

[0105] After obtaining a plurality of test data, analysis can be performed based on the plurality of test data to determine the relationship between ESR and each influencing factor, that is, to determine the effect of each influencing factor on ESR, so that a method of reducing capacitor loss can be determined based on the analysis results.

[0106] It should be noted that, corresponding to step S4 and step S5, after screening the ESR, it is no longer necessary to analyze the relationship between the influencing factor and each data in the ESR. Instead, analysis is performed based on multiple test data to determine the impact of the influencing factor on the effective ESR, that is, to determine the impact of the influencing factor on the equivalent capacitance and equivalent resistance.

[0107] The following is an example of determining the effect of influencing factors on effective ESR based on multiple test data.

[0108] See also Figure 4 , Figure 4 A schematic flow chart of determining the influence of an influencing factor on ESR provided in an embodiment of the present application, S6 may include the following steps:

[0109] S61. Determine the change trend corresponding to each type of test data according to the type corresponding to each type of test data.

[0110] Corresponding to step S3, in the process of testing by the broadband distributed equivalent model, the inlet current and the input voltage can be collected to obtain multiple test data. Accordingly, the multiple test data can be classified based on the inlet current amplitude and the inlet current phase, and the classification corresponding to the equivalent resistance and the equivalent capacitance can be obtained by calculation according to the input voltage and the inlet current, so that multiple types of test data can be obtained.

[0111] Optionally, multiple test data are classified according to the type corresponding to each test data to obtain multiple categories of test data, and then for each category of test data, according to different parameter values ​​corresponding to each influencing factor, the corresponding change trend of each category of test data is obtained.

[0112] Specifically, the inlet current in the test data can be classified to obtain two types of test data corresponding to the inlet current amplitude and the inlet current phase; the equivalent resistance and equivalent capacitance can also be obtained by calculation based on the input voltage and the inlet current, so that the equivalent resistance and equivalent capacitance can also be used as two types of test data.

[0113] After classifying the test data and obtaining various types of test data, for a certain type of test data, the test data corresponding to a certain influencing factor can be found from the test data of this type, and the corresponding multiple test data can be sorted in order from small to large, or from large to small, according to the parameter value of the influencing factor, so as to obtain the change trend of each influencing factor for each type of test data.

[0114] S62. Determine the impact of each influencing factor on ESR based on the changing trend of each type of test data.

[0115] After obtaining the change trend corresponding to each type of data, analysis can be performed based on the change trend to determine the impact of each influencing factor on each type of test data, so that the protection of the capacitor can be improved based on the relationship between the influencing factor and ESR.

[0116] Optionally, the change amount of each type of test data based on different parameter values ​​corresponding to each influencing factor can be determined according to the change trend of each type of test data, and then the impact of each influencing factor on ESR can be determined based on the change amount and a pre-set change threshold.

[0117] Furthermore, in the process of determining the degree of influence of each influencing factor on ESR based on the amount of change combined with a pre-set change threshold, for each influencing factor, the influence trend between the influencing factor and ESR can be determined based on the positive and negative relationship of the amount of change, or the degree of influence between the influencing factor and ESR can be determined based on the size relationship between the absolute value of the amount of change and the change threshold. The way in which each influencing factor affects ESR can also be determined by other means. The embodiment of the present application does not specifically limit the way in which the influencing factor affects ESR.

[0118] The following uses voltage frequency, plate length, plate resistance and capacitance as influencing factors, and determines the relationship between each influencing factor and ESR through multiple types of test data.

[0119] 1. The influencing factor is voltage frequency

[0120] Figure 5A A schematic diagram of the corresponding relationship between voltage frequency and inlet current amplitude provided in an embodiment of the present application, Figure 5B A schematic diagram of the corresponding relationship between voltage frequency and inlet current phase provided in an embodiment of the present application, Figure 5C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance provided in an embodiment of the present application, Figure 5D A schematic diagram of the corresponding relationship between voltage frequency and equivalent capacitance provided in an embodiment of the present application, Figure 5E A schematic diagram of an inlet current variation curve provided in an embodiment of the present application.

[0121] See also FIG. 5A to FIG. 5E , the voltage frequency has a strong correlation with the inlet current and ESR. On the one hand, the increase in voltage frequency will enhance the lossy polarization inside the capacitor medium. On the other hand, the high amplitude inlet current brought by the high frequency of voltage also increases the unevenness of the current distribution on the plate. Therefore, under the action of different voltage frequencies, these influencing factors lead to changes in the inlet current amplitude, phase and ESR. Among them, the capacitor plate length is 20 meters (m) and the voltage is 5 kilovolts (kV) sinusoidal voltage as an example for calculation.

[0122] Depend on FIG. 5A to FIG. 5E It can be seen that with the increase of voltage frequency, the inlet current amplitude increases significantly, while the inlet current phase shows a downward trend, which shows that with the increase of voltage frequency, the capacitor plate current increases, and the lossy polarization of the medium increases. At the same time, the ESR decreases sharply in the area close to the power frequency with the increase of voltage frequency, and gradually tends to be stable, which shows that with the increase of frequency, the ESR shows the characteristics of changing from being dominated by dielectric impedance at power frequency to being dominated by plate resistance at high frequency, which is also mutually confirmed with the trend of the proportion of plate loss and dielectric loss in active loss in the previous article.

[0123] 2. The influencing factor is the length of the plate

[0124] Fig. 6A A schematic diagram of the corresponding relationship between voltage frequency and inlet current amplitude based on different plate lengths provided in an embodiment of the present application, Figure 6B A schematic diagram of the corresponding relationship between voltage frequency and inlet current phase based on different plate lengths provided in an embodiment of the present application, Figure 6C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance based on different electrode lengths provided in an embodiment of the present application, Fig.6D A schematic diagram of the corresponding relationship between voltage frequency and equivalent capacitance based on different electrode lengths provided in an embodiment of the present application.

[0125] The plate length of the capacitor will also affect the inlet current and ESR. As the plate length increases, the plate resistance value will also increase at any time. At the same time, under the influence of the same voltage amplitude and frequency, the plate current distribution will also become flatter as the plate length increases. Among them, using a 5kV sinusoidal voltage as the input voltage, the differences in the inlet current and ESR of capacitors based on different plate lengths are shown.

[0126] Depend on FIG. 6A to FIG. 6D It can be seen that as the length of the plate increases, the amplitude of the inlet current increases, while the phase decreases, and the change becomes more significant as the frequency increases. The ESR also increases with the length of the plate, but near the low frequency band of 50Hz, the ESR of the capacitor with a plate length of 20m shows a trend of first low and then high compared with the ESR of the capacitor with a plate length of 10m. The reason is that near the low frequency band of 50Hz, the ESR is mainly affected by the dielectric impedance, and the plate resistance of the metal film capacitor is relatively small, here it is 0.12 ohms per meter (Ω / m). At a shorter plate length, the plate resistance has limited contribution to the ESR, but as the plate length increases, the plate resistance also increases, and the impact on the ESR also increases.

[0127] Further shortening the length of the plate in the calculation, we can get the ESR change trend under multiple frequencies. It can be analyzed that in the low frequency band, ESR is inversely proportional to the length of the plate, but as the frequency increases, in the high frequency band, ESR is proportional to the length of the plate. In the process of increasing frequency, the ESR of the long plate first lags behind and then leads the short plate. The reason can be explained by the fact that in the low frequency band, ESR is mainly dominated by the equivalent resistance of the medium, and in the high frequency band, ESR is mainly dominated by the plate resistance.

[0128] 3. The influencing factor is the plate resistance

[0129] Fig. 7A A schematic diagram of the corresponding relationship between voltage frequency and inlet current amplitude based on different plate resistances provided in an embodiment of the present application, Figure 7B A schematic diagram of the corresponding relationship between voltage frequency and inlet current phase based on different plate resistances provided in an embodiment of the present application, Figure 7C A schematic diagram of the corresponding relationship between voltage frequency and equivalent resistance based on different plate resistances provided in an embodiment of the present application.

[0130] See also 7A to 7C , capacitors will generate heat during operation, and the application of high-frequency harmonic voltage will make this process more intense. Under the effect of temperature increase, the plate resistance will also increase. In the process of capacitor manufacturing, due to the influence of the manufacturing process, the sprayed metal film becomes thicker due to precision problems, resulting in a decrease in plate resistance. Among them, the capacitor plate length of 20m and the voltage of 5kV sinusoidal voltage are selected as an example for calculation.

[0131] As the plate resistance increases, the amplitude of the inlet current decreases, but the difference between the plate resistance of 0.12Ω / m and the plate resistance of 0.6Ω / m is greater than the difference between the plate resistance of 0.12Ω / m and the plate resistance of 0.024Ω / m; the phase angle of the inlet current decreases as the plate resistance increases, and the change becomes more significant as the frequency increases. The overall ESR also shows an increasing trend as the plate resistance increases.

[0132] 4. The influencing factor is capacitance

[0133] Fig. 8A A schematic diagram of a change trend of the inlet current phase and the inlet current amplitude of a capacitor under different voltage frequencies provided in an embodiment of the present application, Figure 8B A schematic diagram of the change trend of the equivalent resistance and equivalent capacitance of a capacitor under different voltage frequencies provided in an embodiment of the present application, Figure 8C A schematic diagram of the ESR variation trend of capacitors with different capacitances under different voltage frequencies provided in an embodiment of the present application.

[0134] In order to measure the ESR and inlet current of the capacitor, the inlet current is obtained by the current sensor when the experimental platform is operating normally, and the inlet current of the capacitor is measured under different voltage frequencies and voltage amplitudes. Among them, this application selects three types of capacitance, namely 5 microfarads (μF), 10μF and 75μF.

[0135] See also FIG. 8A to FIG. 8C It can be seen that the ESR of capacitors with different capacitance will decrease with the increase of voltage frequency. At the same time, in the 150-500Hz frequency band, as the capacitance increases, the corresponding ESR at the same voltage frequency decreases. The principle can be explained as follows: Taking the comparison between 5μF and 10μF capacitors as an example, considering the definition of capacitor capacitance, its capacitance is linearly related to the plate area. Therefore, assuming that the 10μF capacitor is divided into two from the center of the plate, theoretically two 5μF capacitors can be obtained. The ESR obtained by converting the series-parallel circuit structure to the series circuit structure can be calculated, that is, Similarly, the ESR of a 5μF capacitor can be expressed as At the same time, there is a relationship C p1 =2C p2 , R s1 =R s2 / 2, R d1 =2R d2 Therefore, in this calculation, we can get the quantitative relationship between the ESR of the 5μF and 10μF capacitors, that is, R s2 +3R d2 =2R s1 , ESR and capacitance are linearly correlated.

[0136] Among them, R s1 The ESR of a 10μF capacitor, C p1 The equivalent capacitance of the ESR in a 10μF capacitor, R p1 The equivalent resistance of the ESR in a 10μF capacitor, R d1 represents the metal loss of a 10μF capacitor, R s2 The ESR of a 5μF capacitor, C p2 Represents the equivalent capacitance of the ESR in a 5μF capacitor, R p2 The equivalent resistance of the ESR in a 5μF capacitor, R d2 represents the metal loss of a 5μF capacitor and ω represents the angular frequency.

[0137] In summary, the present application provides an analysis method for equivalent series resistance of a capacitor, by establishing a broadband distributed equivalent model of the capacitor, and adjusting the parameter value of at least one influencing factor in the broadband distributed equivalent model, so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, and then a plurality of test data are obtained through the broadband distributed equivalent model, and finally, the influence of each influencing factor on the equivalent series resistance ESR in the capacitor is determined according to the analysis of the plurality of test data. By determining the influence of each influencing factor on ESR, the influence of the voltage and current distribution inside the capacitor on the capacitor loss can be determined, and by using different voltage frequencies for testing and analysis, the relationship between different influencing factors and ESR can be determined for unstable working conditions such as harmonic voltage and transient voltage, which helps to optimize the design of the capacitor, reduce energy loss and heat generation, and extend the service life of the capacitor.

[0138] Fig. 9 The internal structure diagram of an analysis device provided in an embodiment of the present application. The analysis device may be a terminal or a server. Fig. 9 As shown, the analysis device includes a processor, a memory and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the analysis device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor may implement the analysis method of the equivalent series resistance of the capacitor. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor may implement the analysis method of the equivalent series resistance of the capacitor. Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0139] In one embodiment, an analysis device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0140] Establish a broadband distributed equivalent model of capacitors;

[0141] Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance;

[0142] Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when each of the influencing factors corresponds to a different parameter value;

[0143] An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

[0144] In summary, the embodiment of the present application establishes a broadband distributed equivalent model of the capacitor, and adjusts the parameter value of at least one influencing factor in the broadband distributed equivalent model, so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, and then a plurality of test data are obtained through the broadband distributed equivalent model, and finally, the influence of each influencing factor on the equivalent series resistance ESR in the capacitor is determined based on the analysis of the plurality of test data. By determining the influence of each influencing factor on the ESR, the influence of the voltage and current distribution inside the capacitor on the capacitor loss can be determined, and by using different voltage frequencies for testing and analysis, the relationship between different influencing factors and ESR can be determined for unstable working conditions such as harmonic voltage and transient voltage, which helps to optimize the design of the capacitor, reduce energy loss and heat, and extend the service life of the capacitor.

[0145] In one embodiment, a computer-readable storage medium is provided, storing a computer program, wherein when the computer program is executed by a processor, the processor performs the following steps:

[0146] Establish a broadband distributed equivalent model of capacitors;

[0147] Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance;

[0148] Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when each of the influencing factors corresponds to a different parameter value;

[0149] An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

[0150] In summary, the embodiment of the present application establishes a broadband distributed equivalent model of the capacitor, and adjusts the parameter value of at least one influencing factor in the broadband distributed equivalent model, so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, and then a plurality of test data are obtained through the broadband distributed equivalent model, and finally, the influence of each influencing factor on the equivalent series resistance ESR in the capacitor is determined based on the analysis of the plurality of test data. By determining the influence of each influencing factor on the ESR, the influence of the voltage and current distribution inside the capacitor on the capacitor loss can be determined, and by using different voltage frequencies for testing and analysis, the relationship between different influencing factors and ESR can be determined for unstable working conditions such as harmonic voltage and transient voltage, which helps to optimize the design of the capacitor, reduce energy loss and heat, and extend the service life of the capacitor.

[0151] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0152] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0153] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for analyzing equivalent series resistance of a capacitor, characterized in that: A system for analyzing equivalent series resistance of a capacitor, the method comprising: Establish a broadband distributed equivalent model of capacitors; Adjusting a parameter value of at least one influencing factor in the broadband distributed equivalent model so that the broadband distributed equivalent model is tested when the influencing factor corresponds to different parameter values, the influencing factor comprising at least one of voltage frequency, capacitor plate length, capacitor plate resistance and capacitor capacitance; Acquire a plurality of test data by using the broadband distributed equivalent model, wherein the plurality of test data are acquired by the broadband distributed equivalent model when each of the influencing factors corresponds to a different parameter value; An analysis is performed based on the plurality of test data to determine the influence of each of the influencing factors on the equivalent series resistance ESR in the capacitor, where the ESR includes equivalent capacitance, equivalent inductance and equivalent resistance.

2. The method for analyzing the equivalent series resistance of a capacitor according to claim 1, characterized in that: The analyzing according to the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance (ESR) in the capacitor includes: According to the type corresponding to each of the test data, determining the change trend corresponding to each type of the test data; According to the change trend of each type of the test data, the influence of each influencing factor on the ESR is determined.

3. The method for analyzing the equivalent series resistance of a capacitor according to claim 2, characterized in that: Determining the change trend corresponding to each type of the test data according to the type corresponding to each type of the test data includes: Classifying the plurality of test data according to the type corresponding to each of the test data to obtain multiple categories of test data; For each type of the test data, the change trend corresponding to each type of the test data is obtained according to different parameter values ​​corresponding to each of the influencing factors.

4. The method for analyzing the equivalent series resistance of a capacitor according to claim 2, characterized in that: Determining the influence of each influencing factor on the ESR according to the change trend of each type of the test data includes: Determine, according to the change trend of each type of the test data, the change amount of each type of the test data based on different parameter values ​​corresponding to each of the influencing factors; According to the change amount and in combination with a preset change threshold, the influence of each of the influencing factors on the ESR is determined.

5. The method for analyzing equivalent series resistance of a capacitor according to claim 4, characterized in that: Determining the influence of each of the influencing factors on the ESR according to the change amount and in combination with a preset change threshold includes: For each of the influencing factors, determining the influence trend between the influencing factor and the ESR according to the positive and negative relationship of the change amount; The influence degree between the influencing factor and the ESR is determined according to the magnitude relationship between the absolute value of the change amount and the change threshold.

6. The method for analyzing the equivalent series resistance of a capacitor according to any one of claims 1 to 5, characterized in that: Before analyzing the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance (ESR) of the capacitor, the method further includes: Based on different parameter values ​​corresponding to voltage and frequency respectively, at least one of a current phase error, a current amplitude error and an ESR error is obtained through the broadband distributed equivalent model, wherein the voltage frequency is a frequency corresponding to a voltage input into the broadband distributed equivalent model; According to at least one of the current phase error, the current amplitude error and the ESR error, the equivalent capacitance, the equivalent inductance and the equivalent resistance are screened to obtain an effective ESR; The analyzing according to the plurality of test data to determine the influence of each influencing factor on the equivalent series resistance (ESR) in the capacitor includes: An analysis is performed based on the plurality of test data to determine the influence of the influencing factors on the effective ESR.

7. The method for analyzing the equivalent series resistance of a capacitor according to any one of claims 1 to 5, characterized in that: The test data includes: an inlet current amplitude, an inlet current phase, at least one of the equivalent resistance and the equivalent capacitance.

8. A capacitor equivalent series resistance analysis system, characterized in that: The analysis system of capacitor equivalent series resistance comprises: a power supply, an oscilloscope and a current transformer; The capacitor is connected to the power supply, the oscilloscope is connected to the first electrode of the capacitor through a probe, and the oscilloscope is connected to the second electrode of the capacitor through the current transformer.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor executes the steps of the method for analyzing the equivalent series resistance of a capacitor according to any one of claims 1 to 7.

10. An analysis device, characterized in that: The analysis device comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for analyzing the equivalent series resistance of a capacitor according to any one of claims 1 to 7.

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