Testing device for detecting leakage current of super capacitor

Abstract

The invention discloses a testing device for detecting leakage current of a super capacitor. The testing device comprises the following parts: the super capacitor to be tested, an integrated leakage current testing platform, a communication line, a host and the like, wherein the super capacitors to be tested can be super capacitors which are produced by different manufacturers, have different models and are in multiple batches; an integrated leakage current test platform is composed of a test precision circuit board, a multi-resistance precision resistor, a precision voltmeter and a precision constant voltage power supply. The device can realize leakage current testing of six super capacitors at the same time. In order to reduce / eliminate the damage of a super-capacitor polar plate caused by overlarge charging in the leakage current test process and the comparability of a leakage current test result, according to a charging circuit current model, small-resistor rapid charging and IEC standard rated voltage recommendation resistor charging are carried out. And recommending a current-limiting resistance value during charging according to the current-limiting value of the super capacitor. In addition, in the charging process, an IEC standard unified recommended value small resistor rapid current limiting mode is firstly adopted, and then a rated voltage unified resistor charging mode is adopted, so that the leakage current measurement result is more comparable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of intelligent manufacturing instruments, and mainly relates to a test device for super capacitor leakage current detection. BACKGROUND

[0002] Super capacitors have the advantages of high energy density, excellent cycle performance, strong instantaneous discharge capability, low price and strong environmental adaptability, and are widely used in many fields such as military industry, aerospace and transportation. It is an important development direction of future energy storage. At the same time, super capacitors are also typical components of power supply modules of smart meters. Generally, when the electric energy meter records user electricity information, etc., the power grid will supply power to the power supply module of the electric energy meter, thereby ensuring the realization of the functions of the electric energy meter such as metering, communication, timing, storage, etc. Due to the role of power grid power supply, the super capacitor in the power supply module is in a full charge state at the rated voltage. When the power grid is powered off, due to the strong instantaneous discharge capability of the super capacitor, it can quickly supply power to important units such as the metering module, ensure its continuous work, and switch to a low-energy-consumption working state, and then use the lithium sub-battery of the power supply module to supply power, so that the electric energy meter can also save electricity information and synchronous time information when the power grid is powered off.

[0003] In 2020, the State Grid Corporation issued the "Three-phase Smart Electric Energy Meter Technical Specification" and "Single-phase Smart Electric Energy Meter Technical Specification", which requires that the reliability of electric energy meters should be guaranteed to be greater than or equal to 16 years. In order to ensure that the reliability of the electric energy meter is 0.9 and the service life is greater than or equal to 16 years, at least the reliability of the components used in the electric energy meter should be greater than or equal to 16 years. Through analysis of the failure modes of past field service electric energy meters, it is found that under-voltage after power grid power failure is the highest failure mode of electric energy meters. Even in some provinces, under-voltage failure accounts for about 80% of all failure modes of field electric energy meters, and in most areas, under-voltage failure accounts for more than 50%. Through fault tree analysis, it is found that lithium sub-battery and super capacitor are the weakest links of the power supply module of the electric energy meter, that is, the reliability of the super capacitor to a certain extent determines the reliability of the electric energy meter.

[0004] Given that supercapacitors are typical high-reliability, long-life products, reliability degradation theory is commonly used in their reliability analysis. This involves predicting and assessing the reliability level by analyzing the evolution of supercapacitor performance. Accurate testing of supercapacitor performance indicators such as capacitance, internal resistance, AC impedance, and leakage current is crucial for reliability assessment and prediction. However, there is currently no universally accepted standard for testing supercapacitor performance indicators, both domestically and internationally. Different testing methods inevitably affect the test results, making it difficult to compare parameter test results. The most widely recognized testing standards are IEC 62391 (International Capacitor Committee), Maxwell's Application Note 1007239 (USA), and the State Grid industry standard Q / GDW 11179. All three standards describe the energy and internal resistance testing process of supercapacitors in detail, including the selection of test time points, charging current, discharging current, and test time. Analysis of these three standards shows that the Maxwell standard has a simpler testing process, shorter testing time, and is more suitable for high-current charging and discharging supercapacitors. IEC 62391 and the industry standard have longer testing times and more complex data processing procedures. For engineering applications, Arbin Instruments has developed a series of battery testing equipment to perform internal resistance and capacity testing, covering IEC 62391 and the American Maxwell standard. Princeton Applied Research (PAR), a subsidiary of Ametek, has developed a series of electrochemical workstations to perform AC internal resistance testing.

[0005] Currently, among the three standards mentioned above, the test process for leakage current is not as detailed as that for internal resistance and capacitance tests. However, leakage current is an important indicator that directly affects the voltage level at the load end of the supercapacitor. Taking IEC62391 as an example, in the leakage current test process, it is only stated that (1) before the leakage current test, the charge in the supercapacitor needs to be discharged completely, and the discharge process should be within 1 to 24 hours. (2) First, charge using the rated voltage, and charge to 95% of the rated voltage within a maximum of 30 minutes. Then charge using the rated voltage for 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, 24 hours or 48 hours, and test the leakage current during this process. (3) The voltage source needs to be kept stable, and unless otherwise specified, a resistor of 1kΩ or less is required for protection during constant voltage charging. This leads to some problems in the entire leakage current test process. Problem 1: If the discharge current is too large, the internal temperature will rise, which will cause the electrolyte viscosity to change and may even damage the supercapacitor plates, thus affecting the test results. Therefore, it is necessary to limit the maximum discharge current. Question 2: If charging is performed directly using the rated voltage, considering the internal resistance of the supercapacitor is in the range of 0.1~0.3Ω, the initial current will be enormous, far exceeding the rated current specified in the standard during internal resistance and capacity testing, by tens or even hundreds of times, thus damaging the supercapacitor plates and electrolyte. Question 3: If a series resistor limits the charging current, the standard does not mention the current-limiting resistor, nor how to determine its value. It only mentions that a 1kΩ or lower resistor is needed for protection during constant voltage charging. However, as the supercapacitor's charge increases, its resistance increases towards infinity, meaning the charging current decreases exponentially. How can the charging resistor be determined to ensure charging to 95% of the rated voltage within 30 minutes? Question 4: The intermediate process from charging to 95% of the rated voltage to testing the leakage current at the rated voltage, and the charging time from 95% of the rated voltage to the rated voltage, are not detailed in the standard. Question 5: The data processing procedure for leakage current testing is unclear. The rated voltage is charged for 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, 24 hours, or 48 hours, and leakage current is tested during this period. The leakage current results measured at different times vary by several times, even tens or hundreds of times. How can the measurement results be made comparable?

[0006] Furthermore, there is currently a lack of dedicated equipment for leakage current testing. Although the leakage current testing process shares many similarities with internal resistance and capacitance testing, devices used for testing internal resistance and capacitance are still unsuitable for supercapacitor leakage current testing. For example, Arbin, the most commercially available and professional supercapacitor performance testing equipment, cannot perform supercapacitor leakage current testing. This is partly due to the limited accuracy of its current testing, and partly because the equipment lacks protective resistors during supercapacitor testing, resulting in both positive and negative currents being measured during constant voltage testing, and the physical meaning of negative currents is unclear.

[0007] Based on the above reasons, this patent designs a supercapacitor leakage current testing device for electricity meters. This device is developed with reference to IEC62380 and State Grid industry standard Q / GDW 11179, and is also applicable to the performance testing of supercapacitors in other applications. Considering the sample size issue in the reliability study process, this device has 6 channels to test the leakage current of 6 supercapacitors. In order to eliminate the damage to each supercapacitor caused by the influence of test current and voltage during the leakage current test, the charging stage of the leakage current test adopts the method of fast current limiting with a small resistor of the unified recommended value of IEC standard, followed by charging with a unified resistor of rated voltage, which makes the leakage current measurement results more comparable. Summary of the Invention

[0008] The present invention aims to solve the current lack of dedicated equipment for supercapacitor leakage current testing and the related problems existing in the supercapacitor leakage current testing process. The present invention designs and discloses a testing device for supercapacitor leakage current detection.

[0009] According to some embodiments of the present invention, a testing device for supercapacitor leakage current detection includes an integrated leakage current testing platform with a thin, lightweight aluminum alloy casing. Six independently distributed supercapacitor sockets are arranged side-by-side on the platform, each in a horn-shaped socket design for easy installation and removal of supercapacitors. One side of the front panel features a display screen, a power switch, and corresponding function buttons. The integrated leakage current testing platform internally includes a supercapacitor testing precision circuit board, a leakage current signal acquisition circuit board, a precision voltmeter, a precision constant voltage power supply, and a multi-channel electromagnetic relay switch. The supercapacitor testing precision circuit board integrates six test circuits, a novel design based on the supercapacitor testing principle and procedures. The test circuits utilize 1Ω and 1000Ω precision resistors, as well as adjustable precision resistors, and are connected to the precision voltmeter and adjustable multi-channel regulated power supply via wires. This allows for simultaneous leakage current detection of supercapacitors from different manufacturers, models, and batches, and transmits the supercapacitor leakage current signal to the leakage current signal acquisition circuit board. The leakage current signal acquisition circuit board is a separately designed alumina ceramic circuit board, integrating a high-precision signal acquisition module, a power supply module, a high-speed information processing module, and a host communication module. According to some examples in the invention, the high-precision signal acquisition module uses a 32-bit AD conversion chip to adapt to the acquisition of supercapacitor leakage current signals. According to some examples in the invention, the power supply module supplies power to the entire circuit board, mainly composed of a classic AC-DC module and an AMS1117 chip, providing power to the MCU and various active chips on the circuit board. According to some examples in the invention, the high-speed information processing module uses an STM32 M7 series MCU to efficiently process and acquire the supercapacitor leakage current signal acquired by the AD conversion chip. According to some examples in the invention, the host communication module uses RS-232 communication to achieve communication between the host and the circuit board.

[0010] According to some embodiments of the present invention, a testing device for detecting leakage current in supercapacitors is provided. This addresses the current lack of dedicated equipment for supercapacitor leakage current testing and the absence of standardized industry specifications in the supercapacitor leakage current testing process. Compared with the prior art, the features of the present invention are:

[0011] 1. During the charging process, the method of first using a small resistor with a uniform recommended value according to IEC standards for rapid current limiting, and then charging with a uniform resistor at the rated voltage, makes the leakage current measurement results more comparable.

[0012] 2. Considering the testing requirements of supercapacitors, an adjustable multi-channel regulated power supply is built in to enable the testing of leakage current of different types of supercapacitors. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a test device for detecting leakage current in supercapacitors in an embodiment of the present invention.

[0014] Part numbers in the diagram: 1-Integrated leakage current test platform, 2-Supercapacitor under test, 3-Communication line, 4-Main unit.

[0015] Figure 2 This is a schematic diagram of the leakage current signal acquisition circuit board in the implementation of this invention.

[0016] Part numbers in the diagram: 2a - Power supply module, 2b - High-speed information processing and computing module, 2c - Communication module, 2d - Signal acquisition module.

[0017] Figure 3 This is a schematic diagram of the principle of the novel supercapacitor test circuit board in the implementation of this invention.

[0018] Figure 4 This is a PCB diagram of the novel supercapacitor test circuit in an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the orientation descriptions, such as "up" and "down," are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In the description of the present invention, "multiple" refers to two or more. If "first" and "second" are mentioned, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features. In the description of the present invention, unless otherwise expressly limited, terms such as "set," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in the present invention in combination with the specific content of the technical solution.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings:

[0021] According to some embodiments of the present invention, a test device for detecting leakage current of supercapacitors is provided, wherein the integrated leakage current test platform has a thin and light shell made of aluminum alloy. Six independently distributed pluggable supercapacitor sockets are arranged side-by-side on the platform, and a display screen, power switch, and corresponding function buttons are located on one side of the front. The integrated leakage current test platform (1) internally includes a leakage current signal acquisition circuit board (1-2), a supercapacitor test precision circuit board (1-3), a precision voltmeter, a precision constant voltage power supply, and a multi-channel electromagnetic relay switch. The supercapacitor test precision circuit board (1-3), which integrates six test circuits, is a novel supercapacitor test precision circuit board (1-3) designed based on the supercapacitor test principle and supercapacitor test steps. The supercapacitor test precision circuit board (1-3) uses 1Ω and 1000Ω precision resistors, and an adjustable precision resistor, and is connected to the precision voltmeter and the adjustable multi-channel regulated power supply by wires. It can simultaneously detect the leakage current of supercapacitors (2) from different manufacturers, models, and batches, and transmit the leakage current signal of the supercapacitor (2) to the leakage current signal acquisition circuit board (1-2).

[0022] According to some examples in the invention, the leakage current signal acquisition circuit board (1-2) is a separately designed alumina ceramic circuit board, which integrates a high-precision signal acquisition module, a power supply module, a high-speed information processing and computing module, and a host communication module. The high-precision signal acquisition module uses a 32-bit AD conversion chip to adapt to the signal acquisition of supercapacitor leakage current. According to some examples in the invention, the power supply module supplies power to the entire circuit board. The power supply module mainly consists of a classic AC-DC module and an AMS1117 chip, which can power the MCU and various active chips on the circuit board. According to some examples in the invention, the high-speed information processing and computing module uses an STM32 M7 series MCU, which can efficiently process and acquire the supercapacitor leakage current signal acquired by the AD conversion chip.

[0023] According to some examples in the invention, the host communication module selected the 232 communication method to realize the communication between the host (4) and the leakage current signal acquisition circuit board (1-2).

[0024] According to some embodiments of the present invention, a test device for detecting leakage current of a supercapacitor is provided, taking the capacitor under test C1 as an example, and the test is performed according to the following steps;

[0025] (1) Before testing the leakage current, ensure that the supercapacitor under test is fully discharged, the constant current discharge time is 1h, and the discharge current is i=c*v / t (c is the rated capacitance of the capacitor under test C1, v is the voltage when the supercapacitor starts to discharge, and t is the discharge time 3600s); then, connect the capacitor under test C1 into the circuit, that is, close the S01 switch.

[0026] (2) Close the S11 switch downwards and connect the precision voltmeter across the 1Ω resistor. Calculate the current across the 1Ω resistor using the voltage across it. Select a current-limiting resistor and charge the supercapacitor for 30 minutes using the rated voltage UR (ensure that 95% UR is reached within 30 minutes). The selection process for the current-limiting / protection resistor during low-current charging is as follows;

[0027] First, according to Ohm's law, we can obtain:

[0028]

[0029] Then, according to circuit principles, there exists a proportional relationship between the voltage across capacitor C and the resistance R, as shown in Formula 2:

[0030]

[0031] Based on the above, it can be concluded that the rated voltage UR requires the supercapacitor to reach 95% UR within 30 minutes of charging.

[0032]

[0033] Then we can deduce that:

[0034]

[0035]

[0036] Finally, according to the standard IEC623911-5.7.1 (page 23), the current-limiting resistor is calculated to be 182Ω.

[0037] (3) Then switch the switch to close switch S11 upwards and switch switch S12 downwards to switch to the 1000Ω protection resistor. This 1kΩ resistor is uniformly determined according to the IEC standard. Regardless of the rated capacity and voltage of the supercapacitor being tested, the resistance in the circuit is always this value when the current in the series circuit is read as the leakage current. Then charge at constant voltage for 24 / 48h; that is, 48 ​​hours, which can ensure that the final output supercapacitor value is relatively stable. The first test is 72 hours. After that, the test time can be reduced according to the evolution law during the test. The basis is that the leakage current change is less than 1%. Build a model, input a uniform time, and get the leakage current at that moment. The default is to get the leakage current after 48 hours. The leakage currents of different types and models of supercapacitors can be compared.

[0038] (4) There is another process, which is to use 95% of the rated voltage. For supercapacitors of the same model and manufacturer, the voltage consistency / ΔV should be consistent. Then, starting from this value, test the current value for 24 / 48 hours. The initial leakage current value of the same model and manufacturer should be consistent. Save the voltage data across the 1000Ω resistor. The data test accuracy is in the microampere level.

Claims

1. A testing device for detecting leakage current in supercapacitors, characterized in that, It includes the following components: an integrated leakage current test platform (1); the supercapacitor to be tested (2); a communication line (3); and a host (4).

2. The testing device for detecting leakage current in supercapacitors according to claim 1, characterized in that: The integrated leakage current test platform (1) integrates 6 different leakage current signal acquisition circuit boards (1-2), supercapacitor test precision circuit board (1-3), precision voltmeter, adjustable multi-channel regulated power supply, multi-channel electromagnetic relay switch, etc.

3. The testing device for detecting leakage current in supercapacitors according to claim 2, characterized in that: The integrated leakage current test platform (1) includes a leakage current signal acquisition circuit board (1-2), which is a PCB circuit board containing a power supply module, a high-speed information processing and computing module, a communication module, and a signal acquisition module.

4. The testing device for detecting leakage current in supercapacitors according to claim 1, characterized in that: The integrated leakage current test platform (1) includes a supercapacitor test precision circuit board (1-3). A new type of supercapacitor test circuit is designed based on the supercapacitor test principle and supercapacitor test steps, and the supercapacitor leakage current signal is transmitted to the leakage current signal acquisition circuit board.

5. The testing device for detecting leakage current in supercapacitors according to claim 4, characterized in that: The integrated leakage current test platform (1) includes a supercapacitor test precision circuit board (1-3), which integrates a 1Ω voltage test resistor and a 1000Ω leakage current sampling resistor used in the detection test process, a multi-channel electromagnetic relay switch, an adjustable precision resistor, and wires connecting the supercapacitor test precision circuit board to a precision voltmeter and an adjustable multi-channel regulated power supply.

6. The testing device for detecting leakage current in supercapacitors according to claim 1, characterized in that: The supercapacitor (2) to be tested is installed at the test point on the integrated leakage current test platform (1) by plugging and unplugging. The supercapacitor (2) to be tested can be any model from any manufacturer.

7. The testing device for detecting leakage current in supercapacitors according to claim 1, characterized in that: The host (4) is an industrial control computer that can send instructions. It communicates with the leakage current signal acquisition circuit board (1-2) inside the integrated leakage current test platform (1) through the communication line (3). It can realize the acquisition, storage and transmission of some control instructions of the leakage current of the supercapacitor (2) under test. The device first charges quickly, and then uses a uniform protection resistor for charging.

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