A method for detecting the internal resistance of a super capacitor

Abstract

The application provides a super capacitor internal resistance detection method, comprising the following steps: recording the cumulative charge and discharge capacity of two trigger points, the current value of two trigger points and the voltage value of two trigger points; when the difference of the current value of two trigger points exceeds the first threshold current, calculating the difference of the cumulative charge and discharge capacity of two trigger points, and calculating the voltage change value caused by the charge and discharge capacity of two trigger points through the rated capacity; according to the obtained voltage change value caused by the charge and discharge capacity of two trigger points and the voltage value of two trigger points, calculating the internal resistance voltage of the super capacitor; and according to the obtained internal resistance voltage of the super capacitor and the trigger current value, calculating the internal resistance of the super capacitor. The super capacitor internal resistance detection method provided by the application considers the influence of the capacitor change caused by the short-time large-current charge and discharge on the voltage change of the super capacitor single body, so that the detected internal resistance value of the super capacitor is more accurate.

Description

Technical Field

[0001] This application relates to the field of power electronic control technology, specifically to a method for detecting the internal resistance of a supercapacitor. Background Technology

[0002] Due to their high power, long lifespan, and excellent low-temperature performance, supercapacitors have been increasingly used in fields such as grid energy storage, grid frequency regulation, and automotive backup power in recent years. In practical applications, internal resistance is a crucial parameter for supercapacitors. It characterizes the health of the supercapacitor and the system's connection status, and is used to identify abnormal individual supercapacitors and locate system connection internal resistance issues. The internal resistance of a single supercapacitor cell is typically measured using specialized equipment or testing systems. This requires connecting the supercapacitor to the instrument for measurement, making it impossible to detect the internal resistance of a single supercapacitor cell under normal operating conditions.

[0003] Generally speaking, the battery management system can calculate the battery internal resistance based on the voltage and current changes of individual cells from static to dynamic conditions. When the battery capacity is large, the voltage change during charging and discharging is small in the plateau region, and short-term charging and discharging will not cause changes in battery voltage. The voltage change on the internal resistance caused by the current under dynamic conditions is close to the battery voltage change from static to dynamic conditions, so the battery internal resistance can be calculated based on the voltage and current changes.

[0004] Supercapacitors, compared to batteries, have a wider voltage range with no plateau, relatively smaller capacity, and a larger upper current limit. If the internal resistance of supercapacitors is calculated using the online method described for batteries, the voltage variations in individual supercapacitor cells caused by short-term high-current charging and discharging will significantly impact the calculated internal resistance. Therefore, how to consider the influence of charging and discharging capacity on supercapacitor voltage to make the calculation of supercapacitor internal resistance more accurate has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a method for detecting the internal resistance of a supercapacitor, in order to solve the problem that the voltage variation of a single supercapacitor cell caused by short-term high-current charging and discharging affects the internal resistance of the supercapacitor.

[0006] To address the aforementioned technical problems, this application provides a method for detecting the internal resistance of a supercapacitor, comprising:

[0007] Record the cumulative charge / discharge capacity, current value, and voltage value at the two trigger points;

[0008] When the difference between the current values ​​of the two trigger points exceeds the first threshold current, the difference between the cumulative charge and discharge capacity of the two trigger points is calculated, and the voltage change caused by the charge and discharge capacity of the two trigger points is calculated through the rated capacitor.

[0009] According to the voltage variation value caused by the charge and discharge capacity at the two trigger points and the voltage value at the two trigger points, the internal resistance voltage of the super capacitor is calculated;

[0010] According to the internal resistance voltage of the super capacitor obtained and the two trigger current values, the internal resistance of the super capacitor is calculated.

[0011] Further, the internal resistance voltage of the super capacitor is equal to the difference between the difference of the voltage values at the two trigger points and the voltage variation value caused by the charge and discharge capacity at the two trigger points.

[0012] Further, the internal resistance of the super capacitor is equal to the internal resistance voltage of the super capacitor divided by the difference of the two trigger current values.

[0013] The application also provides a super capacitor internal resistance detection method, comprising:

[0014] The voltage value, cumulative charge and discharge capacity, initial remaining capacity, and current value of the super capacitor cell in a static state are recorded, and the cumulative charge and discharge capacity is obtained by integrating the current and time;

[0015] After triggering a large current, the current size is judged, and when it exceeds the second threshold current, the trigger voltage value, trigger cumulative charge and discharge capacity, and trigger current value of the super capacitor cell are recorded, and the trigger cumulative charge and discharge capacity is obtained by integrating the current and time.

[0016] The remaining capacity of the super capacitor after charge and discharge is calculated according to the cumulative charge and discharge capacity, the trigger cumulative charge and discharge capacity, and the initial remaining capacity, and the theoretical voltage value of the super capacitor is obtained according to the SOC-OCV table and through the super capacitor remaining capacity;

[0017] According to the super capacitor theoretical voltage value and the voltage value in the static state, the super capacitor voltage variation value is calculated;

[0018] The internal resistance voltage of the super capacitor is calculated through the super capacitor voltage variation value, the voltage value in the static state, and the trigger voltage value of the super capacitor cell;

[0019] According to the current value in the static state, the trigger current value, and the internal resistance voltage of the super capacitor, the internal resistance of the super capacitor is calculated.

[0020] Further, the difference between the trigger cumulative charge and discharge capacity and the cumulative charge and discharge capacity is divided by the ampere-hour capacity of the super capacitor to obtain the capacity variation in the charge and discharge process, and the sum of the initial remaining capacity and the capacity variation is the remaining capacity of the super capacitor after charge and discharge.

[0021] Further, the super capacitor voltage change value is the difference between the super capacitor theoretical voltage value and the voltage value in the resting state.

[0022] Further, the internal resistance voltage of the super capacitor is equal to the difference between the trigger voltage value of the super capacitor monomer and the voltage value in the resting state minus the super capacitor voltage change value.

[0023] Further, the internal resistance of the super capacitor is equal to the internal resistance voltage of the super capacitor divided by the difference between the current value in the resting state and the trigger current value.

[0024] The super capacitor internal resistance detection method provided by the application provides a detection method for detecting the internal resistance of the super capacitor monomer by the super capacitor management system under the normal operation condition of the device, considers the influence of the voltage change of the super capacitor monomer caused by the charge and discharge capacity change of the short-time large current charge and discharge, and makes the detected super capacitor internal resistance value more accurate; the application also considers the actual operation condition of the super capacitor, detects the super capacitor internal resistance under complex working conditions by multiple calculation methods, and is suitable for the super capacitor internal resistance measurement method under the working condition of frequent current change and irregular change. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0026] Figure 1 The flow structure schematic diagram of the super capacitor internal resistance detection method provided by the embodiment of the present application is shown in the figure.

[0027] Figure 2 The flow structure schematic diagram of the super capacitor internal resistance detection method provided by the embodiment of the present application is shown in the figure.

[0028] Figure 3a The structure schematic diagram of the super capacitor monomer equivalent to the theoretical capacitor and resistor in series at the first trigger point provided by the embodiment of the present application is shown in the figure.

[0029] Figure 3b The structure schematic diagram of the super capacitor monomer equivalent to the theoretical capacitor and resistor in series at the second trigger point provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0030] The technical solutions in the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of the present application.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0032] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements, it can be wireless connection, or it can be wired connection. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0034] Figure 1 The flow structure schematic diagram of the super capacitor internal resistance detection method provided by the embodiment of the present application is shown in FIG. 1. Referring to FIG. 1, the super capacitor internal resistance detection method provided by the embodiment of the present application includes the following steps. Figure 1 The present application provides a super capacitor internal resistance detection method, which includes:

[0035] S11, record the voltage value, cumulative charge and discharge capacity, initial remaining power and current value of the super capacitor cell in the static state, the cumulative charge and discharge capacity is obtained by integrating the current and time;

[0036] S12, after triggering a large current, judge the current size, when the current exceeds the second threshold current, record the trigger voltage value, trigger cumulative charge and discharge capacity and trigger current value of the super capacitor cell, the trigger cumulative charge and discharge capacity is obtained by integrating the current and time;

[0037] S13. Calculate the remaining charge of the supercapacitor after charging and discharging based on the cumulative charge and discharge capacity, the triggered cumulative charge and discharge capacity, and the initial remaining charge. Then, find the theoretical voltage value of the supercapacitor based on the SOC-OCV table and the remaining charge of the supercapacitor.

[0038] S14. Calculate the voltage change of the supercapacitor based on the theoretical voltage value of the supercapacitor and the voltage value under the static state.

[0039] S15. Calculate the internal resistance voltage of the supercapacitor using the voltage change value of the supercapacitor, the voltage value in the static state, and the trigger voltage value of the supercapacitor cell.

[0040] S16. Calculate the internal resistance of the supercapacitor based on the current value, the trigger current value, and the internal resistance voltage of the supercapacitor in the static state.

[0041] In step S11, the supercapacitor is first kept in a static state for a certain period of time to ensure internal stability and prevent it from being affected by the charging and discharging current. The voltage value of each supercapacitor cell in the static state is recorded by the supercapacitor management system (CMS). Cumulative charge and discharge capacity Initial remaining power Current value If it remains in a static state, update the data. After triggering a large current, determine the current magnitude. If the current exceeds the threshold current, record the trigger voltage value of the supercapacitor cell. Triggering cumulative charge and discharge capacity Trigger current value The larger the current here, the greater the proportion of voltage change caused by internal resistance, the more accurate the internal resistance calculation, and the more difficult it is to trigger. Based on the stated cumulative charge / discharge capacity... The triggering of cumulative charge and discharge capacity and the initial remaining power Calculate the remaining charge of the supercapacitor after charging and discharging. , Where AH is the supercapacitor capacity, calculated based on the SOC-OCV table and the remaining charge of the supercapacitor. Theoretical voltage value of supercapacitor was seized. Because the supercapacitor was in a static state during the first recording, the supercapacitor voltage value... It can be approximated as the voltage value of a single supercapacitor cell in a static state. ,Right now Calculate the voltage change of the supercapacitor caused by the charging and discharging capacity. , Through the change in supercapacitor voltage The voltage value in the static state and the trigger voltage value of the super capacitor cell Calculate the internal resistance voltage of the super capacitor , according to the current value in the static state , the trigger current value and the internal resistance voltage of the super capacitor Calculate the internal resistance R of the super capacitor, .

[0042] The above method accurately eliminates the influence of voltage change caused by large current charging and discharging capacity, and for considering the actual super capacity operation current is large, the current changes frequently and irregularly, the static condition is omitted, and only the resistance is calculated according to the current change in a short time. The super capacitor is different from the battery, the SOC-OCV is close to the theoretical capacity, which can be approximated as a straight line, that is, the charging and discharging capacity is proportional to the voltage change caused by charging and discharging, so the super capacitor can be equivalent to the series connection of the theoretical capacity and the resistance.

[0043] Figure 2 The flow structure diagram of the super capacitor internal resistance detection method provided by the embodiment of the application is shown in the figure. Referring to Figure 2 The super capacitor internal resistance detection method comprises:

[0044] S21, record the cumulative charging and discharging capacity of the two trigger points, the current value of the two trigger points and the voltage value of the two trigger points;

[0045] S22, when the difference between the current values of the two trigger points exceeds the first threshold current, calculate the difference between the cumulative charging and discharging capacities of the two trigger points, and calculate the voltage change value caused by the charging and discharging capacity of the two trigger points through the rated capacity;

[0046] S23, according to the obtained voltage change value caused by the charging and discharging capacity of the two trigger points and the voltage value of the two trigger points, calculate the internal resistance voltage of the super capacitor;

[0047] S24, according to the obtained internal resistance voltage of the super capacitor, and the current value of the two trigger points, calculate the internal resistance of the super capacitor.

[0048] Figure 3a The structure diagram of the super capacitor cell at the first trigger point provided by the embodiment of the application is equivalent to the series connection of the theoretical capacity and the resistance; Figure 3b The structure diagram of the super capacitor cell at the second trigger point provided by the embodiment of the application is equivalent to the series connection of the theoretical capacity and the resistance. Referring to Figure 2 and Figure 3a and Figure 3b, the cumulative charge and discharge capacity at the two trigger points, the current value at the two trigger points and the voltage value at the two trigger points are recorded by the super capacitor management system (CMS), in the embodiment of the application, the cumulative charge and discharge capacity at the maximum current and the minimum current in a short time are recorded 、 current value 、 and voltage value 、 , the cumulative charge and discharge capacity 、 is obtained by the integral calculation of the current and the time, when the difference of the current value 、 exceeds the first threshold current, the difference of the cumulative charge and discharge capacity at the two trigger points is calculated , the voltage change value caused by the charge and discharge capacity at the two trigger points is calculated by the rated capacitance , , and then the internal resistance voltage of the super capacitor is calculated according to the voltage value 、 , ; according to the obtained internal resistance voltage of the super capacitor , and the current value at the two trigger points 、 , the internal resistance of the super capacitor is calculated .

[0049] The super capacitor internal resistance detection method provided by the application provides a detection method for detecting the internal resistance of a super capacitor single body by a super capacitor management system under normal operation conditions of equipment, considers the influence of the voltage change of the super capacitor single body caused by the charge and discharge capacity change of the short-time large current charge and discharge, and makes the detected internal resistance value of the super capacitor more accurate; the application also considers the actual operation conditions of the super capacitor, detects the internal resistance of the super capacitor under complex conditions by multiple calculation methods, and is suitable for the super capacitor internal resistance measurement method under the condition of frequent current change and irregular change.

[0050] Obviously, the above embodiments are only examples for clearly illustrating, and are not limited to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the application.

Claims

1. A method for detecting the internal resistance of a supercapacitor, characterized in that, include: Record the cumulative charge / discharge capacity, current value, and voltage value at the two trigger points; When the difference between the current values ​​of the two trigger points exceeds the first threshold current, the difference between the cumulative charge and discharge capacity of the two trigger points is calculated, and the voltage change caused by the charge and discharge capacity of the two trigger points is calculated through the rated capacitor. The internal resistance voltage of the supercapacitor is calculated based on the voltage change caused by the two charge / discharge capacities at the two trigger points and the voltage values ​​at the two trigger points. The internal resistance of the supercapacitor is calculated based on the obtained internal resistance voltage of the supercapacitor and the current values ​​at the two trigger points.

2. The method for detecting the internal resistance of a supercapacitor according to claim 1, characterized in that, The internal resistance voltage of the supercapacitor is equal to the difference between the voltage values ​​at the two trigger points and the voltage change caused by the charging and discharging capacity at the two trigger points.

3. The method for detecting the internal resistance of a supercapacitor according to claim 1, characterized in that, The internal resistance of the supercapacitor is equal to the internal resistance voltage of the supercapacitor divided by the difference between the two trigger point current values.

4. A method for detecting the internal resistance of a supercapacitor, characterized in that, include: Record the voltage value, cumulative charge and discharge capacity, initial remaining charge, and current value of a single supercapacitor cell when it is in a static state. The cumulative charge and discharge capacity is obtained by integrating the current and time. After triggering a large current, the magnitude of the current is determined. When the current exceeds the second threshold current, the trigger voltage value, the cumulative charge and discharge capacity, and the trigger current value of the supercapacitor cell are recorded. The cumulative charge and discharge capacity is obtained by integrating the current and time. The remaining charge of the supercapacitor after charging and discharging is calculated based on the cumulative charge and discharge capacity, the triggered cumulative charge and discharge capacity, and the initial remaining charge. The theoretical voltage value of the supercapacitor is then obtained from the SOC-OCV table and the remaining charge of the supercapacitor. Calculate the voltage change of the supercapacitor based on the theoretical voltage value and the voltage value under static conditions; The internal resistance voltage of the supercapacitor is calculated by the voltage change value of the supercapacitor, the voltage value in the static state, and the trigger voltage value of the supercapacitor cell. The internal resistance of the supercapacitor is calculated based on the current value in the static state, the trigger current value, and the internal resistance voltage of the supercapacitor.

5. The method for detecting the internal resistance of a supercapacitor according to claim 4, characterized in that, The difference between the triggered cumulative charge / discharge capacity and the cumulative charge / discharge capacity is divided by the ampere-hour capacity of the supercapacitor to obtain the change in charge during the charge / discharge process. The sum of the initial remaining charge and the change in charge is the remaining charge of the supercapacitor after the charge / discharge process.

6. The method for detecting the internal resistance of a supercapacitor according to claim 4, characterized in that, The voltage change value of the supercapacitor is the difference between the theoretical voltage value of the supercapacitor and the voltage value under the static state.

7. The method for detecting the internal resistance of a supercapacitor according to claim 4, characterized in that, The internal resistance voltage of the supercapacitor is equal to the difference between the trigger voltage value of the supercapacitor cell and the voltage value in the static state, minus the voltage change value of the supercapacitor.

8. The method for detecting the internal resistance of a supercapacitor according to claim 4, characterized in that, The internal resistance of the supercapacitor is equal to the internal resistance voltage of the supercapacitor divided by the difference between the current value and the trigger current value in the static state.

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