Single-cell ESR determination method and system suitable for super capacitor module

Abstract

The invention discloses a single-cell ESR determination method and system suitable for a super capacitor module, and the method comprises the steps: charging a super capacitor monomer at a constant current to a preset rated voltage, stopping charging, and recording the moment as a charging end moment; constant-voltage processing is carried out on the super-capacitor monomers under the rated voltage, and the duration is at least a preset time period so as to ensure that the internal electric field of the capacitor is stable; discharging from a rated voltage to a preset minimum working voltage at a constant current, and recording a voltage value at a preset time point after the start of discharging; and according to the initial voltage of each discharge, the voltage value at the preset time point and the discharge current, calculating the equivalent series resistance of the super capacitor monomer through a formula. By adopting the steps of constant-current charging, discharging and constant-voltage processing, the stability of an electric field in a capacitor in the measurement process is ensured, the measurement precision of an ESR value is improved, the performance state of a battery cell can be accurately known, and important basic data for evaluating the consistency of all battery cells in a system is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery management systems and relates to a single-cell ESR determination method and system applicable to a supercapacitor module. Background Art

[0002] In the current field of battery management system (BMS) technology, although BMS plays a key role in monitoring the voltage, current, temperature of the battery pack, performing charge balancing, and protecting the battery from overcharge or over-discharge damage, there are common technical limitations: most existing BMS systems do not have the function of directly detecting the cell internal resistance (ESR, Equivalent Series Resistance). As an important parameter for measuring battery performance, the change of cell internal resistance directly affects the thermal management, efficiency, consistency and overall life of the battery.

[0003] The increase of the internal resistance of the battery cell, according to Joule's law (Q = I 2 RT) will directly lead to an increase in the heat generated by the battery cell during operation, which not only accelerates the aging process of the battery, but may also cause safety problems. In addition, the uneven increase in the internal resistance of the battery cell will also destroy the consistency between the batteries in the battery pack, which is the basis for maintaining efficient and reliable operation of the battery pack. When a traditional BMS detects inconsistencies in battery cell voltage or capacity, it will initiate a balancing strategy to try to restore consistency. However, if this inconsistency is caused by changes in internal resistance, simple voltage or capacity balancing may not fundamentally solve the problem. On the contrary, it may further aggravate the inconsistency between batteries due to operations such as over-discharge, forming a vicious circle, and ultimately leading to accelerated capacity decay of the entire battery system, a reduction in the available energy range, and affecting user experience and system performance.

[0004] Given the importance of cell internal resistance detection and its profound impact on the performance evaluation and maintenance of the battery management system, the lack of technology that can effectively monitor the cell internal resistance in the current market has become one of the bottlenecks restricting the further development of battery technology. Therefore, developing a technology that can accurately and real-time calculate and monitor the cell internal resistance is of great significance for improving the overall performance of the battery pack, extending its service life, and ensuring safe operation.

[0005] It is based on the above background that the present invention proposes a solution for the module design composed of supercapacitor cells. By realizing the calculation of the internal resistance of the cell, it provides battery system designers with important data support for evaluating key performance indicators such as cell consistency and aging degree. Summary of the invention

[0006] The purpose of the present invention is to solve the problem in the prior art that the internal resistance of a battery cell cannot be accurately and real-time calculated and monitored, and to provide a single-cell ESR determination method and system suitable for a supercapacitor module.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for determining the ESR of a single cell applicable to a supercapacitor module comprises the following steps:

[0009] S1, charging the supercapacitor monomer at a constant current to a preset rated voltage, stopping charging and recording this moment as the charging end moment;

[0010] S2, subjecting the supercapacitor monomer to constant voltage treatment at rated voltage for at least a preset period of time to ensure that the electric field inside the capacitor is stable;

[0011] S3, discharging from the rated voltage to a preset minimum operating voltage at a constant current, and recording the voltage value at a preset time point after the start of the discharge;

[0012] S4, according to the starting voltage of each discharge and the voltage value at a preset time point, as well as the discharge current, the equivalent series resistance of the supercapacitor monomer is calculated by a formula.

[0013] The supercapacitor monomer is charged at a constant current to a preset rated voltage, and the charging is stopped and recorded as the charging end time, specifically:

[0014] Choose a charger with constant current function and output current and voltage range that matches the supercapacitor specifications;

[0015] Connect the positive and negative electrodes of the charger to the corresponding terminals of the supercapacitor respectively, set the charging current according to the specifications of the supercapacitor, use the preset rated voltage as the charging termination voltage, and then start the charger to charge the supercapacitor at a constant current while ensuring that the current and voltage remain within the set range;

[0016] When the charging voltage reaches the preset rated voltage, the charger stops charging, records the voltage value at the end of charging, and disconnects the charger from the supercapacitor.

[0017] The supercapacitor monomer is subjected to constant voltage treatment at a rated voltage for at least a preset period of time to ensure that the electric field inside the capacitor is stable. The specific steps are as follows:

[0018] Set the constant voltage parameters, adjust the output voltage of the power supply to the rated voltage of the supercapacitor according to the specific specifications of the supercapacitor, and preset the duration;

[0019] Start the constant voltage treatment, start the power supply to apply a constant voltage to the supercapacitor for treatment, and continuously monitor the change of current until the current gradually decreases to a stable value;

[0020] At the end of the treatment, when the current is monitored to be stable at a low level, the current value at the end of the treatment is recorded, and the connection between the power supply and the supercapacitor is disconnected.

[0021] The method of discharging from the rated voltage to a preset minimum operating voltage with a constant current and recording the voltage value at a preset time point after the start of the discharge is specifically:

[0022] Make sure the supercapacitor to be tested has been pre-charged to its rated voltage;

[0023] Parameter setting, setting the discharge current value of the supercapacitor; determining the minimum operating voltage at which the discharge is terminated; and setting one or more preset time points for recording the voltage value of the supercapacitor during the discharge process;

[0024] Adjusting the adjustable current source to a preset discharge current value, and starting the current source to begin constant current discharge of the supercapacitor;

[0025] Monitoring and recording: When the discharge starts, start the timer to start timing; continue to monitor the voltage value on the voltmeter, and when each preset time point is reached, record the voltage value at that time; continue the discharge process until the voltage of the supercapacitor drops to the preset minimum operating voltage.

[0026] The formula is:

[0027]

[0028] Wherein, Ur is the discharge starting voltage, Ui is the voltage value at the preset time point of the i-th discharge, and I is the discharge current.

[0029] The steps S1-S3 should be repeated at least three times to improve the accuracy and reliability of the test data.

[0030] The supercapacitor monomer is charged with a constant current of 100A until its voltage reaches 2.7V and then the charging stops;

[0031] Under the condition that the voltage is maintained at 2.7V, the supercapacitor monomer is subjected to constant voltage treatment for at least 2 minutes to ensure that the internal electric field of the capacitor reaches a stable state;

[0032] The battery was discharged at a constant current of 100A from 2.7V until the voltage dropped to 1.5V.

[0033] The supercapacitor monomer is charged with a constant current of 50A until its voltage reaches 2.7V and then charging stops;

[0034] Under the condition that the voltage is maintained at 2.7V, the supercapacitor monomer is subjected to constant voltage treatment for at least 2 minutes to ensure that the internal electric field of the capacitor reaches a stable state;

[0035] The battery was discharged at a constant current of 50A from 2.7V until the voltage dropped to 1.5V.

[0036] A single-cell ESR determination system suitable for a supercapacitor module includes the following modules:

[0037] The charging module is used to charge the supercapacitor monomer to a preset rated voltage at a constant current, and stop charging when the rated voltage is reached, and record this moment as the charging end moment;

[0038] A constant voltage processing module is used to perform constant voltage processing on the charged supercapacitor monomer at a rated voltage for a duration of at least a preset time period to ensure that the electric field inside the capacitor is stable;

[0039] A discharge module, used to discharge from the rated voltage to a preset minimum operating voltage at a constant current, and record the voltage value at a preset time point after the start of discharge;

[0040] The calculation module is used to calculate the equivalent series resistance of the supercapacitor monomer through a preset formula according to the starting voltage of the discharge module, the voltage value at a preset time point and the discharge current.

[0041] The system also includes a storage module for storing data during each charging, constant voltage treatment, and discharging process and a calculated equivalent series resistance value.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention discloses a single-cell ESR determination method applicable to a supercapacitor module, which ensures the stability of the internal electric field of the capacitor during the measurement process by adopting constant current charging and discharging, and constant voltage processing steps, thereby improving the measurement accuracy of the ESR value and helping designers to understand the performance status of the cell more accurately.

[0044] The ability to measure the ESR value of each cell in the module provides designers with important basic data for evaluating the consistency of all cells in the system. By comparing the ESR values ​​of different cells, cells with large performance differences can be discovered in a timely manner, so that appropriate measures can be taken to optimize or replace them, ensuring the performance stability and reliability of the entire module.

[0045] The ESR value of the battery cell will gradually increase with the increase of usage time, which is an important sign of battery cell aging. By regularly measuring the ESR value of the battery cell, the aging degree of the battery cell can be monitored in real time, providing early warning information for designers so that timely measures can be taken to extend the service life of the module or replace it.

[0046] Based on accurate ESR measurement results, designers can more reasonably select battery cells, optimize module structure, improve heat dissipation design, etc., thereby improving the performance and reliability of the entire supercapacitor module.

[0047] By promptly detecting and handling cells with abnormal performance, failure of the entire module due to cell failure can be avoided, thereby reducing the maintenance cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 A flow chart of a method for determining the ESR of a single cell applicable to a supercapacitor module of the present invention;

[0050] Figure 2 This is a test current and voltage curve diagram of Scheme 1 of the present invention;

[0051] Figure 3 This is a test current and voltage curve diagram of Scheme 2 of the present invention;

[0052] Figure 4 This is a test current and voltage curve diagram of Scheme 3 of the present invention;

[0053] Figure 5 This is a test current and voltage curve diagram of Scheme 4 in the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0056] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0057] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0058] See also Figure 1 , is a flow chart of a method for determining the ESR of a single cell applicable to a supercapacitor module in the present invention, which specifically includes the following steps:

[0059] S1, charging the supercapacitor monomer at a constant current to a preset rated voltage, stopping charging and recording this moment as the charging end moment.

[0060] Specifically:

[0061] Preparation stage: Select a charger with constant current function and output current and voltage range that match the supercapacitor specifications, and check the supercapacitor to ensure that it is not damaged or leaking, and that parameters such as nominal voltage and capacity meet the use requirements;

[0062] Charging stage: Connect the positive and negative electrodes of the charger to the corresponding terminals of the supercapacitor respectively, set the appropriate charging current and the preset rated voltage as the charging termination voltage according to the specifications of the supercapacitor, and then start the charger to charge the supercapacitor at a constant current, while observing the changes in current and voltage to ensure that they remain within the set range;

[0063] End of charging: When the charging voltage reaches the preset rated voltage, the charger automatically stops charging. At this time, the voltage value at the end of charging is recorded, and the charger is disconnected from the supercapacitor in time to avoid unnecessary energy loss or safety risks.

[0064] S2, subjecting the supercapacitor monomer to constant voltage treatment at rated voltage for at least a preset period of time to ensure that the electric field inside the capacitor is stable.

[0065] The specific steps are:

[0066] Set constant voltage parameters: According to the specific specifications of the supercapacitor, adjust the output voltage of the power supply to the rated voltage of the supercapacitor, and preset a duration, which should be at least a few minutes to a few hours. The specific duration depends on the specifications of the supercapacitor and the actual application requirements.

[0067] Start constant voltage treatment: Start the power supply and start applying a constant voltage to the supercapacitor for treatment. During this process, the current changes need to be continuously monitored until the current gradually decreases to a stable value or close to zero. At this time, it can be considered that the electric field inside the supercapacitor has stabilized;

[0068] End of treatment: When the current is monitored to be stable at a low level or close to zero, the current value at the end of the treatment is recorded, and the connection between the power supply and the supercapacitor is immediately disconnected to prevent energy loss or safety risks.

[0069] S3, discharging from the rated voltage to a preset minimum operating voltage at a constant current, and recording the voltage value at a preset time point after the start of the discharge.

[0070] Specifically:

[0071] Preparation stage:

[0072] Equipment preparation: Ensure that the supercapacitor to be tested has been pre-charged to its rated voltage; prepare an adjustable current source to discharge the supercapacitor at a constant current; prepare a high-precision voltmeter to monitor the voltage change of the supercapacitor during the discharge process in real time; and prepare a timer or stopwatch to accurately record the discharge time.

[0073] Parameter setting: Set the appropriate discharge current value according to the specific specifications of the supercapacitor and the actual application requirements; determine the minimum operating voltage for discharge termination; and set one or more preset time points to record the voltage value of the supercapacitor during the discharge process.

[0074] Discharge process:

[0075] Connecting equipment: Correctly connect the supercapacitor to the positive and negative poles of the adjustable current source to ensure the correct current flow path; at the same time, connect the positive and negative poles of the voltmeter to both ends of the supercapacitor to monitor its voltage changes in real time.

[0076] Start discharge: adjust the adjustable current source to the preset discharge current value, and start the current source to start constant current discharge of the supercapacitor.

[0077] Monitoring and recording: When the discharge starts, start the timer to start timing; continue to monitor the voltage value on the voltmeter, and immediately record the voltage value at each preset time point; continue the discharge process until the voltage of the supercapacitor drops to the preset minimum operating voltage.

[0078] Discharge termination and subsequent operations:

[0079] Discharge termination: When the voltage drops to the preset minimum operating voltage, the adjustable current source is stopped immediately to end the discharge process; then the supercapacitor is disconnected from the current source and voltmeter to ensure safety.

[0080] Data analysis: The discharge performance of the supercapacitor is analyzed based on the recorded voltage values ​​at the preset time points after the start of discharge and the voltage values ​​at the end of discharge. The discharge curve can be further drawn to intuitively display the discharge characteristics of the supercapacitor and provide data support for subsequent evaluation and application.

[0081] Repeat the above steps S1-S3 at least three times to improve the accuracy and reliability of the test data.

[0082] S4, according to the starting voltage of each discharge and the voltage value at a preset time point, as well as the discharge current, the equivalent series resistance of the supercapacitor monomer is calculated by a formula.

[0083] The formula is:

[0084]

[0085] Wherein, Ur is the discharge starting voltage, Ui is the voltage value at the preset time point of the i-th discharge, the preset time point is the voltage value at the 100 ms moment of the discharge, and I is the discharge current.

[0086] In the industry standard QC / T 741-2014 "Automotive Supercapacitors", the following methods are provided for testing supercapacitors:

[0087] At room temperature, test the internal resistance of the capacitor monomer according to the following steps:

[0088] a) The capacitor monomer is charged to the rated voltage Ur with a constant current I, and this time is recorded as T0;

[0089] b) The capacitor monomer is discharged at a constant current I to the minimum operating voltage Umin, and the voltage Ui at T0+30ms is recorded;

[0090] c) Repeat steps a) to b) 3 times

[0091] d) Calculate the DC internal resistance of the third cycle as the internal resistance of the capacitor monomer according to the following calculation formula

[0092]

[0093] The above method is the supercapacitor ESR test method specified in QC / T 741-2014. For this purpose, the experiment was conducted on a supercapacitor monomer with a specification of 3.0V 3400F. In order to better meet the actual application scenario, the upper limit of the supercapacitor voltage was set to 2.7V and the lower limit of the supercapacitor voltage was set to 1.5V. Then the following two experiments were conducted respectively:

[0094] Experiment 1:

[0095] Step 1: Fully charge the single cell at 100A and stop charging when it reaches 2.7V;

[0096] Step 2: Discharge at 100A until 1.5V stops;

[0097] Step 3: Repeat steps 1-2 three times.

[0098] Experiment 2:

[0099] Step 1: Fully charge the single cell at 50A and stop charging when it reaches 2.7V;

[0100] Step 2: Discharge at 50A until 1.5V and then stop discharging;

[0101] Step 3: Repeat steps 1-2 three times.

[0102] The internal resistance of the supercapacitor can be calculated using the following formula:

[0103]

[0104] Among them, Ur is the discharge starting voltage, U1, U2, and U3 are the voltages at the 30ms moment of the first, second, and third discharges, respectively.

[0105] The calculated internal resistance of the supercapacitor is 0.095mΩ for 100A discharge and 0.096mΩ for 50A discharge. According to the specification, the internal resistance of the supercapacitor is ≤0.2mΩ. The deviation between this test method and the actual value is too large, so this method is not suitable for BMS to calculate the ESR of the supercapacitor system battery cell; see Figure 2 and Figure 3 The test current and voltage curves for Scheme 1 and Scheme 2 are shown respectively.

[0106] Table 1 Test data table

[0107]

[0108] The test method of the above industry standard has been modified, constant pressure has been added in the middle, and the above test method has been changed to:

[0109] Solution 3:

[0110] Step 1: Fully charge the single cell at 100A and stop charging when it reaches 2.7V;

[0111] Step 2: 2.7V constant voltage for 2 minutes;

[0112] Step 3: Discharge at 100A until 1.5V stops;

[0113] Step 4: Repeat steps 1-3 three times.

[0114] Solution 4:

[0115] Step 1: Fully charge the single cell at 50A and stop charging when it reaches 2.7V;

[0116] Step 2: 2.7V constant voltage for 2 minutes;

[0117] Step 3: Discharge at 50A until 1.5V and then stop discharging;

[0118] Step 4: Repeat steps 1-3 three times.

[0119] The internal resistance of the supercapacitor can be calculated using the following formula:

[0120]

[0121] Among them, Ur is the discharge starting voltage, U1, U2, and U3 are the voltages at the 30ms moment of the first, second, and third discharges, respectively.

[0122] The calculated internal resistance of the supercapacitor is 0.13mΩ for 100A discharge and 0.126mΩ for 50A discharge. According to the specification, the internal resistance of the supercapacitor is ≤0.2mΩ. This test method is close to the actual value, so the BMS can refer to this method to calculate the ESR of the supercapacitor system battery cell; see Figure 4 and Figure 5 The test current and voltage curves of Scheme 3 and Scheme 4 are shown respectively.

[0123] Table 2 Test data table

[0124]

[0125] Through the above test, it is found that the ESR of the supercapacitor calculated after the single cell voltage is constant is more in line with the ESR of the battery cell, but there is a problem: the voltage value taken in the above formula is the voltage value at the 30ms moment after discharge. The reason for taking 30ms is that the response accuracy time of AC power is about 30ms, but combined with the actual working conditions, the single cell voltage update cycle collected by the BMS board is 100ms, so the BMS cannot collect the voltage value of the 30ms of discharge in time. The above test data is taken as the voltage value of the 100ms of discharge to calculate the ESR of the supercapacitor. The calculation results are shown in the following table:

[0126] Table 3 Calculation results

[0127]

[0128] After changing the ESR calculation time of the above supercapacitor from 30ms in the standard to 100ms, the ESR value obtained by constant voltage calculation of the monomer and the ESR value obtained by non-constant voltage calculation of the monomer are basically the same, and are close to the ESR≤0.2mΩ in the battery cell specification. At the same time, they are less affected by the discharge current value. For example, the ESR values ​​calculated by 100A and 50A discharge are basically close and there is no obvious difference. Therefore, this method can be used by BMS to calculate the internal resistance ESR value of each battery cell in the supercapacitor system. It should be noted that the denominator current value of constant voltage or non-constant voltage is different during calculation. However, when using the above method, a fixed value method is selected when designing BMS. The calculated supercapacitor internal resistance ESR value is more accurate and also solves the problem that the BMS board in the industry cannot calculate the internal resistance of the battery cell.

[0129] An embodiment of the present invention is a single-cell ESR determination system applicable to a supercapacitor module, comprising the following modules:

[0130] The charging module is used to charge the supercapacitor monomer to a preset rated voltage at a constant current, and stop charging when the rated voltage is reached, and record this moment as the charging end moment;

[0131] A constant voltage processing module is used to perform constant voltage processing on the charged supercapacitor monomer at a rated voltage for a duration of at least a preset time period to ensure that the electric field inside the capacitor is stable;

[0132] A discharge module, used to discharge from the rated voltage to a preset minimum operating voltage at a constant current, and record the voltage value at a preset time point after the start of discharge;

[0133] The calculation module is used to calculate the equivalent series resistance of the supercapacitor monomer through a preset formula according to the starting voltage of the discharge module, the voltage value at a preset time point and the discharge current.

[0134] It includes a storage module for storing data during each charging, constant voltage treatment, and discharging process as well as the calculated equivalent series resistance value.

[0135] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the ESR of a single cell of a supercapacitor module, characterized in that: The following steps are involved: S1, charging the supercapacitor monomer at a constant current to a preset rated voltage, stopping charging and recording this moment as the charging end moment; S2, subjecting the supercapacitor monomer to constant voltage treatment at rated voltage for at least a preset period of time to ensure that the electric field inside the capacitor is stable; S3, discharging from the rated voltage to a preset minimum operating voltage at a constant current, and recording the voltage value at a preset time point after the start of the discharge; S4, according to the starting voltage of each discharge and the voltage value at a preset time point, as well as the discharge current, the equivalent series resistance of the supercapacitor monomer is calculated by a formula.

2. A method for determining the ESR of a single cell suitable for a supercapacitor module as claimed in claim 1, characterized in that: The supercapacitor monomer is charged at a constant current to a preset rated voltage, and the charging is stopped and recorded as the charging end time, specifically: Choose a charger with constant current function and output current and voltage range that matches the supercapacitor specifications; Connect the positive and negative electrodes of the charger to the corresponding terminals of the supercapacitor respectively, set the charging current according to the specifications of the supercapacitor, use the preset rated voltage as the charging termination voltage, and then start the charger to charge the supercapacitor at a constant current while ensuring that the current and voltage remain within the set range; When the charging voltage reaches the preset rated voltage, the charger stops charging, records the voltage value at the end of charging, and disconnects the charger from the supercapacitor.

3. A method for determining the ESR of a single cell suitable for a supercapacitor module as claimed in claim 1, characterized in that: The supercapacitor monomer is subjected to constant voltage treatment at a rated voltage for at least a preset period of time to ensure that the electric field inside the capacitor is stable. The specific steps are as follows: Set the constant voltage parameters, adjust the output voltage of the power supply to the rated voltage of the supercapacitor according to the specific specifications of the supercapacitor, and preset the duration; Start the constant voltage treatment, start the power supply to apply a constant voltage to the supercapacitor for treatment, and continuously monitor the change of current until the current gradually decreases to a stable value; At the end of the treatment, when the current is monitored to be stable at a low level, the current value at the end of the treatment is recorded, and the connection between the power supply and the supercapacitor is disconnected.

4. A method for determining the ESR of a single cell suitable for a supercapacitor module as claimed in claim 1, characterized in that: The method of discharging from the rated voltage to a preset minimum operating voltage with a constant current and recording the voltage value at a preset time point after the start of the discharge is specifically: Make sure the supercapacitor to be tested has been pre-charged to its rated voltage; Parameter setting, setting the discharge current value of the supercapacitor; determining the minimum operating voltage for discharge termination; and setting one or more preset time points for recording the voltage value of the supercapacitor during the discharge process; Adjusting the adjustable current source to a preset discharge current value, and starting the current source to begin constant current discharge of the supercapacitor; Monitoring and recording: When the discharge starts, the timer starts timing; Continuously monitor the voltage value on the voltmeter and record the voltage value at each preset time point; The discharge process continues until the voltage of the supercapacitor drops to the preset minimum operating voltage.

5. A method for determining the ESR of a single cell applicable to a supercapacitor module as claimed in claim 1, characterized in that: The formula is: Wherein, Ur is the discharge starting voltage, Ui is the voltage value at the preset time point of the i-th discharge, and I is the discharge current.

6. A method for determining the ESR of a single cell applicable to a supercapacitor module as claimed in claim 1, characterized in that: The steps S1-S3 should be repeated at least three times to improve the accuracy and reliability of the test data.

7. A method for determining the ESR of a single cell applicable to a supercapacitor module as claimed in claim 1, characterized in that: The supercapacitor monomer is charged with a constant current of 100A until its voltage reaches 2.7V and then the charging stops; Under the condition that the voltage is maintained at 2.7V, the supercapacitor monomer is subjected to constant voltage treatment for at least 2 minutes to ensure that the internal electric field of the capacitor reaches a stable state; The battery was discharged at a constant current of 100A from 2.7V until the voltage dropped to 1.5V.

8. A method for determining the ESR of a single cell applicable to a supercapacitor module as claimed in claim 1, characterized in that: The supercapacitor monomer is charged with a constant current of 50A until its voltage reaches 2.7V and then charging stops; Under the condition that the voltage is maintained at 2.7V, the supercapacitor monomer is subjected to constant voltage treatment for at least 2 minutes to ensure that the internal electric field of the capacitor reaches a stable state; The battery was discharged at a constant current of 50A from 2.7V until the voltage dropped to 1.5V.

9. A single-cell ESR determination system suitable for a supercapacitor module, characterized in that: Includes the following modules: The charging module is used to charge the supercapacitor monomer to a preset rated voltage at a constant current, and stop charging when the rated voltage is reached, and record this moment as the charging end moment; A constant voltage processing module is used to perform constant voltage processing on the charged supercapacitor monomer at a rated voltage for a duration of at least a preset time period to ensure that the electric field inside the capacitor is stable; A discharge module, used to discharge from the rated voltage to a preset minimum operating voltage at a constant current, and record the voltage value at a preset time point after the start of discharge; The calculation module is used to calculate the equivalent series resistance of the supercapacitor monomer through a preset formula according to the starting voltage of the discharge module, the voltage value at a preset time point and the discharge current.

10. A single-cell ESR determination system suitable for a supercapacitor module as claimed in claim 9, characterized in that: The system also includes a storage module for storing data during each charging, constant voltage treatment, and discharging process and a calculated equivalent series resistance value.

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