Super capacitor internal resistance detection method

Abstract

The invention provides a super capacitor internal resistance detection method. The method comprises the following steps: recording two times of trigger point accumulated charge and discharge capacity, two times of trigger point current values and two times of trigger point voltage values; when the difference value of the current values of the two triggering points exceeds a first threshold current, calculating the difference value of the accumulated charge and discharge capacities of the two triggering points, and calculating a voltage change value caused by the charge and discharge capacities of the two triggering points through a rated capacitor; calculating the internal resistance voltage of the super capacitor according to the obtained voltage change value caused by the charging and discharging capacities of the two triggering points and the voltage values of the two triggering points; and calculating the internal resistance of the super capacitor according to the obtained internal resistance voltage of the super capacitor and the two trigger current values. According to the super-capacitor internal resistance detection method provided by the invention, the internal resistance of the single super-capacitor is detected through the super-capacitor management system, and the influence of the voltage change of the single super-capacitor caused by the capacitance change of short-time large-current charging and discharging is considered, 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, and particularly to a method for detecting the internal resistance of a super capacitor. Background Art

[0002] Due to characteristics such as high power, long life, and good low-temperature performance, super capacitors have gradually been applied in fields such as power grid energy storage, power grid frequency modulation, and automotive backup power sources in recent years. During the actual product application process of super capacitors, the internal resistance is an important parameter, which can be used to characterize the health status of super capacitors and the connection of the system, and is used for the identification of abnormal over-capacity monomers and the positioning of system connection internal resistance problems. Generally, the internal resistance of a super capacitor monomer is measured using professional equipment or a test system, and the super capacitor needs to be connected to the instrument for measurement, and it is impossible to detect the internal resistance of the super capacitor monomer under normal operating conditions.

[0003] Generally speaking, the battery management system can calculate the battery internal resistance based on the voltage change and current change of the battery monomer from static to dynamic. When the battery capacity is large, the charge and discharge voltage change in the plateau area is small, and short-term charge and discharge will not cause the battery voltage to change. 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, and the battery internal resistance can be calculated based on the voltage and current changes.

[0004] However, super capacitors have the characteristics of a large voltage change range, no plateau area, relatively small capacity, and large current upper limit compared with batteries. If the internal resistance of a super capacitor is detected according to the above-mentioned online calculation method of battery internal resistance, the voltage change of the super capacitor monomer caused by the capacity change during short-term large-current charge and discharge will have a greater impact on the calculation of the internal resistance of the super capacitor. Therefore, how to consider the influence of charge and discharge capacity on the voltage of the super capacitor to make the calculation of the internal resistance value of the super capacitor 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 super capacitor to solve the problem that the voltage change of the super capacitor monomer caused by the capacity change during short-term large-current charge and discharge affects the internal resistance of the super capacitor.

[0006] To solve the above technical problems, this application provides a method for detecting the internal resistance of a super capacitor, including: Recording the cumulative charge and discharge capacity of two trigger points, the current values of the two trigger points, and the voltage values of the two trigger points; When the difference between the current values of the two trigger points exceeds the first threshold current, calculating the difference between the cumulative charge and discharge capacities of the two trigger points, and calculating the voltage change value caused by the charge and discharge capacities of the two trigger points through the rated capacitance; Calculating the internal resistance voltage of the super capacitor according to the obtained voltage change value caused by the charge and discharge capacities of the two trigger points and the voltage values of the two trigger points; Calculate the internal resistance of the supercapacitor based on the obtained internal resistance voltage of the supercapacitor and the two trigger current values.

[0007] Further, the internal resistance voltage of the supercapacitor is equal to the difference between the difference of the two trigger point voltage values and the voltage change value caused by the charge-discharge capacity of the two trigger points.

[0008] Further, the internal resistance of the supercapacitor is equal to the internal resistance voltage of the supercapacitor divided by the difference between the two trigger current values.

[0009] This application also provides a method for detecting the internal resistance of a supercapacitor, including: Record the voltage value, cumulative charge-discharge capacity, initial remaining power, and current value of the supercapacitor cell in a static state, and the cumulative charge-discharge capacity is obtained by integrating current and time; After triggering a large current, judge the magnitude of the current. When it exceeds the second threshold current, record the trigger voltage value, trigger cumulative charge-discharge capacity, and trigger current value of the supercapacitor cell, and the trigger cumulative charge-discharge capacity is obtained by integrating current and time; Calculate the remaining power of the supercapacitor after charge and discharge based on the cumulative charge-discharge capacity, the trigger cumulative charge-discharge capacity, and the initial remaining power, and obtain the theoretical voltage value of the supercapacitor by referring to the SOC-OCV table and using the remaining power of the supercapacitor; Calculate the voltage change value of the supercapacitor based on the theoretical voltage value of the supercapacitor and the voltage value in the static state; Calculate the internal resistance voltage of the supercapacitor through the voltage change value of the supercapacitor, the voltage value in the static state, and the trigger voltage value of the supercapacitor cell; Calculate the internal resistance of the supercapacitor based on the current value in the static state, the trigger current value, and the internal resistance voltage of the supercapacitor.

[0010] Further, the difference between the trigger cumulative charge-discharge capacity and the cumulative charge-discharge capacity is divided by the ampere-hour capacity of the supercapacitor to obtain the charge and discharge process power change, and the sum of the initial remaining power and the power change is the remaining power of the supercapacitor after charge and discharge.

[0011] Further, the voltage change value of the supercapacitor is the difference between the theoretical voltage value of the supercapacitor and the voltage value in the static state.

[0012] Further, 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.

[0013] Further, 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.

[0014] The method for detecting the internal resistance of a supercapacitor provided by the present invention provides a method for detecting the internal resistance of a supercapacitor monomer through a supercapacitor management system under normal operating conditions of the device. It takes into account the influence of the change in the charge-discharge capacity of short-term large-current charge and discharge on the voltage change of the supercapacitor monomer, making the detected internal resistance value of the supercapacitor more accurate. This application also considers the actual operating conditions of the supercapacitor and detects the internal resistance of the supercapacitor under complex conditions through various calculation methods. It is applicable to the measurement method of the internal resistance of the supercapacitor under the conditions of frequent and irregular current changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a schematic flow structure diagram of the method for detecting the internal resistance of a supercapacitor provided by an embodiment of the present invention; Figure 2 It is a schematic flow structure diagram of the method for detecting the internal resistance of a supercapacitor provided by an embodiment of the present invention; Figure 3a It is a schematic structure diagram of the supercapacitor monomer at the first trigger point equivalent to a structure in which a theoretical capacitor and a resistor are connected in series; Figure 3b It is a schematic structure diagram of the supercapacitor monomer at the second trigger point equivalent to a structure in which a theoretical capacitor and a resistor are connected in series. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the present application in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0018] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0019] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0020] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0021] Figure 1 It is a schematic flow structure diagram of the supercapacitor internal resistance detection method provided by the embodiment of the present invention. Referring to Figure 1 , the present application provides a supercapacitor internal resistance detection method, including: S11. Record the voltage value, cumulative charge-discharge capacity, initial remaining power, and current value of the supercapacitor monomer in a static state. The cumulative charge-discharge capacity is obtained by integrating the current and time; S12. After triggering a large current, judge the magnitude of the current. When it exceeds the second threshold current, record the trigger voltage value, trigger cumulative charge-discharge capacity, and trigger current value of the supercapacitor monomer. The trigger cumulative charge-discharge capacity is obtained by integrating the current and time; S13. Calculate the remaining power of the supercapacitor after charge and discharge according to the cumulative charge-discharge capacity, the trigger cumulative charge-discharge capacity, and the initial remaining power, and obtain the theoretical voltage value of the supercapacitor by referring to the SOC-OCV table through the remaining power of the supercapacitor; S14. Calculate the supercapacitor voltage change value according to the theoretical voltage value of the supercapacitor and the voltage value in the static state; S15. Calculate the internal resistance voltage of the supercapacitor through the supercapacitor voltage change value, the voltage value in the static state, and the trigger voltage value of the supercapacitor monomer; 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 under the static state.

[0022] When performing step S11, first ensure that the supercapacitor is in a static state for a certain period of time to stabilize the inside of the supercapacitor and make it unaffected by the charge and discharge current. Record the voltage value of the supercapacitor monomer in the static state through the supercapacitor management system (CMS). Accumulated charge and discharge capacity Initial remaining power Current value . If it continues to be in a static state, update the data. After triggering a large current, judge the current magnitude. When the current exceeds the threshold current, record the trigger voltage value of the supercapacitor monomer. Triggered accumulated charge and discharge capacity Trigger current value . Here, the greater the current, the greater the proportion of the voltage change caused by the internal resistance, the more accurate the internal resistance calculation, and correspondingly, it is more difficult to trigger. According to the accumulated charge and discharge capacity The triggered accumulated charge and discharge capacity And the initial remaining power Calculate the remaining power of the supercapacitor after charge and discharge. , , where AH is the supercapacitor capacity. Based on the SOC-OCV table and through the remaining power of the supercapacitor Obtain the theoretical voltage value of the supercapacitor. . Because it is in a static state during the first record, the supercapacitor voltage value Can be approximated as the voltage value of the supercapacitor monomer in the static state. , that is Calculate the supercapacitor voltage change value caused by the charge and discharge capacity. , . Through the supercapacitor voltage change value The voltage value under the static state And the trigger voltage value of the supercapacitor monomer Calculate the internal resistance voltage of the supercapacitor. . According to the current value under the static state Trigger current value And the internal resistance voltage of the supercapacitor Calculate the internal resistance R of the supercapacitor. .

[0023] The above method more accurately eliminates the influence of voltage changes caused by large current charge and discharge capacity. Considering the actual operating conditions of supercapacitors with large operating current, frequent and irregular current changes, the static condition is omitted, and the resistance is calculated only based on short-time current changes. Different from batteries, the SOC-OCV of supercapacitors is close to the theoretical capacitance and can be approximated as a straight line, that is, the charge and discharge capacity is proportional to the voltage change caused by charge and discharge. Therefore, the supercapacitor can be equivalent to a series of theoretical capacitance and resistance.

[0024] Figure 2 It is a schematic flow structure diagram of the supercapacitor internal resistance detection method provided by the embodiment of the present invention. Refer to Figure 2 , the supercapacitor internal resistance detection method includes: S21. Record the cumulative charge and discharge capacity at two trigger points, the current values at two trigger points, and the voltage values at two trigger points; S22. When the difference between the current values at two trigger points exceeds the first threshold current, calculate the difference between the cumulative charge and discharge capacities at the two trigger points, and calculate the voltage change value caused by the charge and discharge capacities at the two trigger points through the rated capacitance; S23. Calculate the internal resistance voltage of the supercapacitor according to the obtained voltage change value caused by the charge and discharge capacities at the two trigger points and the voltage values at the two trigger points; S24. Calculate the internal resistance of the supercapacitor according to the obtained internal resistance voltage of the supercapacitor and the two trigger current values.

[0025] Figure 3a It is a schematic structural diagram of the supercapacitor single body equivalent to a series of theoretical capacitance and resistance at the first trigger point provided by the embodiment of the present invention; Figure 3b It is a schematic structural diagram of the supercapacitor single body equivalent to a series of theoretical capacitance and resistance at the second trigger point provided by the embodiment of the present invention. Refer to Figure 2 and Figure 3a and Figure 3b , the supercapacitor management system (CMS) records the cumulative charge and discharge capacity at two trigger points, the current values at two trigger points, and the voltage values at two trigger points. In the embodiment of the present invention, the cumulative charge and discharge capacity at the maximum and minimum current within a short time is recorded , current value , and voltage value , , the cumulative charge and discharge capacity , is obtained by integrating current and time. When the current value , the difference exceeds the first threshold current, calculate the difference between the cumulative charge and discharge capacities at two trigger points , and through the rated capacitance Calculate the voltage change value caused by charging and discharging the capacity at the trigger point twice , and then according to the voltage value , , calculate the internal resistance voltage of the supercapacitor ; According to the obtained internal resistance voltage of the supercapacitor , and the two trigger current values , , calculate the internal resistance of the supercapacitor .

[0026] The method for detecting the internal resistance of a supercapacitor provided by the present invention provides a method for detecting the internal resistance of a supercapacitor monomer through a supercapacitor management system under normal operating conditions of the device. It considers the influence of the change in the charging and discharging capacity of the supercapacitor monomer caused by the charging and discharging capacity change during short-term large-current charging and discharging, making the detected internal resistance value of the supercapacitor more accurate; This application also considers the actual operating conditions of the supercapacitor, and detects the internal resistance of the supercapacitor under complex conditions through various calculation methods, which is applicable to the measurement method of the internal resistance of the supercapacitor under the conditions of frequent and irregular current changes.

[0027] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present application.

Claims

1. A method for detecting the internal resistance of a supercapacitor, characterized in that, Including: Recording the cumulative charge-discharge capacity at two trigger points, the current values at the two trigger points, and the voltage values at the two trigger points; When the difference between the current values at the two trigger points exceeds the first threshold current, calculating the difference in the cumulative charge-discharge capacity at the two trigger points, and calculating the voltage change value caused by the charge-discharge capacity at the two trigger points through the rated capacitance; Calculating the internal resistance voltage of the supercapacitor based on the obtained voltage change value caused by the charge-discharge capacity at the two trigger points and the voltage values at the two trigger points; Calculating the internal resistance of the supercapacitor 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 difference in the voltage values at the two trigger points and the voltage change value caused by the charge-discharge 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 in the two trigger current values.

4. A method for detecting the internal resistance of a supercapacitor, characterized in that, Including: Recording the voltage value, cumulative charge-discharge capacity, initial remaining charge, and current value of the supercapacitor cell in a static state, where the cumulative charge-discharge capacity is obtained by integrating the current over time; After triggering a large current, determining the magnitude of the current. When it exceeds the second threshold current, recording the trigger voltage value, trigger cumulative charge-discharge capacity, and trigger current value of the supercapacitor cell, where the trigger cumulative charge-discharge capacity is obtained by integrating the current over time; Calculating the remaining charge of the supercapacitor after charge and discharge based on the cumulative charge-discharge capacity, the trigger cumulative charge-discharge capacity, and the initial remaining charge, and obtaining the theoretical voltage value of the supercapacitor by referring to the SOC-OCV table and using the remaining charge of the supercapacitor; Calculating the voltage change value of the supercapacitor based on the theoretical voltage value of the supercapacitor and the voltage value in the static state; Calculating the internal resistance voltage of the supercapacitor through the voltage change value of the supercapacitor, the voltage value in the static state, and the trigger voltage value of the supercapacitor cell; Calculating the internal resistance of the supercapacitor 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 trigger cumulative charge-discharge capacity and the cumulative charge-discharge capacity is divided by the ampere-hour capacity of the supercapacitor to obtain the charge change during the charge-discharge process, and the sum of the initial remaining charge and the charge change is the remaining charge of the supercapacitor after charge and discharge.

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 in 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 in the static state and the trigger current value.

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