Method for exploring battery limiting current based on optimization method
Through the battery limit current calculation method based on the preferred method, the problem of difficult to accurately calculate the battery limit current is solved, and efficient and accurate calculation of the battery limit current is achieved, thereby avoiding battery damage and improving the performance of electric vehicles.
Patent Information
- Application Number
- CN202411306645.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2024-12-27
AI Technical Summary
The prior art is difficult to efficiently and accurately calculate the battery limit current, which leads to the occurrence of battery over-discharge/overcharging, affecting battery life and the performance of electric vehicles.
By using a method based on the preferred method, the battery's SOC, cut-off time, cut-off voltage and current interval are determined, and the discharge and charging limit currents under each SOC are calculated using the discharge and charging preferred method, and the limit current value is gradually approached through the left and right test current and judgment principles. .
Improves the calculation accuracy of the battery limit current, avoids battery damage, ensures efficient energy release and charging, extends battery life, and reduces charging time.
Smart Images
Figure CN119199598A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of current detection, and in particular to a method for exploring the limiting current of a battery based on an optimization method. Background Art
[0002] The battery management system is an important component of electric vehicles, and the peak power of the battery is its key estimation quantity, which provides a reference for the power distribution and energy control of the electric vehicle system, and is used to measure the acceleration and climbing performance of the electric vehicle, as well as its braking energy recovery function during braking. This can effectively prevent the occurrence of over-discharge / over-charge of the battery pack, thereby increasing the life of the battery pack. The exploration of power is inevitably inseparable from the exploration of the limiting current. However, if you try blindly, it will take a lot of time and testing resources. Therefore, the present invention proposes a measurement method to efficiently and accurately obtain the battery power pulse limiting current value. Summary of the invention
[0003] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a method for exploring the battery limit current based on the optimization method. The present invention can accurately calculate the limit current under each SOC.
[0004] To achieve the above object, the present invention provides the following technical solutions:
[0005] A method for finding a battery limiting current based on an optimization method comprises the following steps:
[0006] S1. Determine the SOC of the battery, as well as the cut-off time, cut-off voltage and current range corresponding to each SOC;
[0007] S2. Based on the data in step S1, during the battery discharge process, the discharge limit current of each SOC is calculated using the discharge optimization method;
[0008] S3. Based on the data in step S1, during the battery charging process, a charging optimization method is used to calculate the charging limit current of each SOC.
[0009] As a further technical solution of the present invention: the process of calculating the discharge limit current of each SOC using the discharge optimization method is as follows:
[0010] S21, the current range of the current SOC is [I min ,I max ], the cut-off time is t, the cut-off voltage is U; based on the current interval [I min ,I max ]Calculate the left discharge test current I l,D And right discharge test current I r,D ;
[0011] S22, use the left discharge test current I respectively at the current SOC l,D Or right discharge test current I r,D Discharge cut-off time t;
[0012] Record the left discharge test current I l,D During discharge, the maximum voltage across the battery is recorded as the left discharge cut-off voltage U l,D ;
[0013] Record the discharge test current I r,D During discharge, the maximum voltage across the battery is recorded as the right discharge cut-off voltage U r,D ;
[0014] S23. Formulate discharge judgment principles according to the discharge situation; the discharge judgment principles include discharge judgment one, discharge judgment two, discharge judgment three and discharge judgment four;
[0015] S24, when any one of the discharge judgments 1, 2 and 3 is met, the original current interval in step S21 is replaced with the obtained new current interval, and the battery is continuously discharged according to the contents of steps S21 to S23;
[0016] When the discharge judgment 4 is met, the current SOC limit current can be obtained, that is, at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and |U r,D -U|≤0.01V, the right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the current SOC limit current; at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V or |U r,D -U|≤0.01V, the left discharge cut-off voltage U l,D The corresponding left discharge test current I l,D Or right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the limiting current of the current SOC.
[0017] As a further technical solution of the present invention: the left discharge test current I l,D The calculation formula is as follows:
[0018] I l,D =Imin +0.382(I max -I min );
[0019] Right discharge test current I r,D The calculation formula is as follows:
[0020] I r,D =I min +0.618(I max -I min ).
[0021] As a further technical solution of the present invention: the discharge judgment principle is specifically expressed as follows:
[0022] Discharge judgment 1: If the left discharge cut-off voltage U l,D Greater than or equal to the cut-off voltage U, and the right discharge cut-off voltage U r,D If the current interval is less than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left discharge test current I l,D , then the right end point of the current interval is updated to the right discharge test current I r,D , thereby forming a new current interval;
[0023] Discharge judgment 2: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D If both are less than or equal to the cut-off voltage U, the left endpoint of the current interval remains unchanged, and the right endpoint of the current interval is updated to the left discharge test current I l,D , thereby forming a new current interval;
[0024] Discharge judgment three: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|>0.01V and |U r,D -U|>0.01V, the left end point of the current interval is updated to the right discharge test current I r,D , then keep the right end point of the current interval unchanged to form a new current interval;
[0025] Discharge judgment 4: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and / or |U r,D -U|≤0.01V, get the current limit current of the current SOC;
[0026] As a further technical solution of the present invention: the specific process of calculating the charging limit current of each SOC using the charging optimization method is as follows: The process of calculating the charging limit current of each SOC using the charging optimization method is as follows:
[0027] S31, the current range of the current SOC is [I min ,I max ], the cut-off time is t, the cut-off voltage is U; based on the current interval [I min ,I max ]Calculate the left charging test current I l,C And right charging test current I r,C ;
[0028] S32, using the left charging test current I respectively at the current SOC l,C Or right charging test current I r,C Charging cut-off time t;
[0029] Record the left charging test current I l,C During charging, the maximum voltage across the battery is recorded as the left charging cut-off voltage U l,C ;
[0030] Record the right charging test current I r,C During charging, the maximum voltage across the battery is recorded as the right charging cut-off voltage U r,C ;
[0031] S33. Formulate charging judgment principles according to the charging situation; the charging judgment principles include charging judgment 1, charging judgment 2, charging judgment 3 and charging judgment 4;
[0032] S34, when any one of the charging judgments 1, 2 and 3 is met, the original current interval in step S31 is replaced with the new current interval, and the battery is continuously charged according to the contents of steps S31 to S33;
[0033] When the charging judgment 4 is met, the current SOC limit current can be obtained, that is, at the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and |UU r,C |≤0.01V, the right charging cut-off voltage U r,C Corresponding right charging test current I r,C That is the current SOC limit current; at the left charging cut-off voltage U l and right charging cut-off voltage U r are less than or equal to the cut-off voltage U, and |UUl,C |≤0.01V or |UU r,C |≤0.01V, at this time the left charging cut-off voltage U l Corresponding left charging test current I l,C Or right charging cut-off voltage U r Corresponding right charging test current I r,C That is the limiting current of the current SOC.
[0034] As a further technical solution of the present invention: left charging test current I l,C The calculation formula is as follows:
[0035] I l,C =I min +0.382(I max -I min );
[0036] Right charging test current I r,C The calculation formula is as follows:
[0037] I r,C =I min +0.618(I max -I min ).
[0038] As a further technical solution of the present invention: the charging judgment principle is as follows:
[0039] Charging judgment 1: If the left charging cut-off voltage U l,C Less than or equal to the cut-off voltage U, and the right charging cut-off voltage U r,C If the current is greater than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left charging test current I l,C , then the right end point of the current interval is updated to the right charging test current I r,C , thereby forming a new current interval;
[0040] Charging judgment 2: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C If both are greater than or equal to the cut-off voltage U, the right endpoint of the current interval is updated to the left charging test current I l,C , the left endpoint of the current interval remains unchanged, thus forming a new current interval;
[0041] Charging judgment three: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C If both are less than or equal to the cut-off voltage U, the right endpoint of the current interval remains unchanged, and the left endpoint of the current interval is updated to the right charging test current I r,C , thereby forming a new current interval;
[0042] Charging judgment 4: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and / or |UU r,C |≤0.01V, get the current limit current of the current SOC;
[0043] As a further technical solution of the present invention: the specific steps of step S1 are as follows:
[0044] S11, determine the SOC of the battery; divide the SOC range from 0% to 100% into 5 equally spaced intervals, [0%, 20%], [20%, 40%], [40%, 60%], [60%, 80%], [80%, 100%];
[0045] S12, determining the cut-off time corresponding to each SOC: according to each interval divided in step S1, determining the time required to fill the SOC of the interval or discharge the SOC of the interval, which is the cut-off time of the interval;
[0046] S13, determining the cut-off voltage corresponding to each SOC: measuring and obtaining the highest voltage value allowed to be reached during charging or discharging in each interval in step S1, and the highest voltage value is the cut-off voltage corresponding to the interval;
[0047] S14, determining the current interval corresponding to each SOC: measuring the minimum current value or the maximum current value during the charging process or the discharging process in each interval, and the interval formed by the minimum current value and the maximum current value is the current interval of the interval.
[0048] Compared with the prior art, the present invention has the following beneficial effects:
[0049] 1. The present invention first determines the SOC of the battery and its corresponding cut-off time, cut-off voltage and current interval, providing a solid data basis for the subsequent calculation of the limiting current. This detailed interval setting makes the battery characteristics (such as internal resistance, capacity decay rate, etc.) change relatively little at each SOC, thereby improving the accuracy of calculating the limiting current at the SOC. During the discharge process, the application of the discharge optimization method is based on the data of step S1, and the discharge limiting current of each SOC can be calculated more accurately. This helps to avoid damage to the battery due to exceeding its safe discharge capacity, while also ensuring that the battery can release energy at optimal efficiency in different discharge stages. Similarly, during the charging process, the charging optimization method uses the data of step S1 to accurately calculate the charging limiting current of each SOC. This helps to prevent overcharging of the battery and protect the internal structure of the battery from damage, while improving charging efficiency and reducing charging time.
[0050] 2. The present invention lists the operation of each step in detail, starting from determining the current interval, to testing by left and right discharge test currents, to making discharge judgments based on the test results, and finally determining a new current interval or limit current. The entire process is clear and easy to understand and implement. At the same time, the mathematical golden ratio (0.382 and 0.618) is used to determine the test current, which helps to approach the true limit current value as efficiently as possible within a limited number of tests, reflecting the combination of scientificity and efficiency.
[0051] 3. The present invention comprehensively covers the possible voltage and current relationship through four charge and discharge judgment conditions, ensuring the accuracy and reliability of the calculation. In particular, the fourth judgment condition further refines the determination standard of the limiting current by setting the threshold value of the voltage difference (0.01V), thereby improving the accuracy. When the limiting current determination condition is not met, the current interval is iteratively updated and the test is repeated to gradually approach the true limiting current value, which embodies the idea of the optimization algorithm and helps to improve the accuracy of the calculation results. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] Figure 1 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION
[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0054] See also Figure 1 , the present invention includes the following contents.
[0055] 1. Determine the battery parameters.
[0056] Determine the battery's SOC, as well as the cut-off time, cut-off voltage, and current range corresponding to each SOC. The details are as follows:
[0057] S11. Determine the SOC of the battery:
[0058] SOC (State of Charge) is the battery power state, which indicates the percentage of the remaining battery power to the total capacity. In this step, the battery SOC range needs to be divided into several intervals according to the test or application requirements.
[0059] For example, the SOC range from 0% (fully discharged) to 100% (fully charged) may be divided into five or more intervals of equal or unequal spacing, such as [0%, 20%], [20%, 40%], ..., [80%, 100%].
[0060] S12, determine the cut-off time corresponding to each SOC:
[0061] The cut-off time refers to the maximum time limit for the battery to be tested or operated within each SOC. The setting of this time depends on many factors, including the type of battery (such as lithium-ion battery, lead-acid battery, etc.), the purpose of the test (such as performance evaluation, life test, etc.), and safety considerations. The cut-off time for each SOC may be different. For example, a shorter cut-off time may be set at a low SOC to prevent the battery from being over-discharged, while a longer cut-off time may be set at a high SOC to fully evaluate the battery performance.
[0062] S13, determine the cut-off voltage corresponding to each SOC:
[0063] The cut-off voltage refers to the lowest or highest voltage value that the battery is allowed to reach during the discharge or charge process. This value is crucial to protect the battery from damage. During the discharge process, when the battery voltage drops below a certain set cut-off voltage, the discharge should be stopped to prevent the battery from over-discharging. Similarly, during the charging process, when the battery voltage rises above a certain set cut-off voltage, the charging should be stopped to prevent the battery from overcharging. Each SOC may correspond to one or more cut-off voltage values, which are determined according to the battery characteristics and test requirements.
[0064] S14, determine the current range corresponding to each SOC:
[0065] The current range refers to the minimum and maximum charge and discharge current values allowed by the battery within each SOC. These values are critical to ensuring that the battery operates under safe and efficient conditions. The setting of the current range depends on the type, capacity, internal resistance of the battery, and the specific needs of the test or application. For example, when evaluating battery performance, it may be necessary to use larger charge and discharge currents to simulate load changes in actual usage scenarios; when protecting the battery from damage, it is necessary to limit the charge and discharge currents to avoid overheating or damage to the internal structure of the battery.
[0066] 2. Calculate the discharge limit current.
[0067] Based on the battery parameters, during the battery discharge process, the discharge optimization method is used to calculate the discharge limit current of each SOC. The details are as follows:
[0068] S21, the current range of the current SOC is [I min ,I max ], the cut-off time is t, and the cut-off voltage is U.
[0069] Based on the current interval [I min ,I max ]Calculate the left discharge test current I l,D And right discharge test current I r,D , I l,D =I min +0.382(I max -I min ), I r,D =I min +0.618(I max -I min ).
[0070] S22, use the left discharge test current I respectively at the current SOC l,D Or right discharge test current I r,D Discharge cut-off time t.
[0071] Record the left discharge test current I l,D During discharge, the maximum voltage across the battery is recorded as the left discharge cut-off voltage U l,D .
[0072] Record the discharge test current I r,D During discharge, the maximum voltage across the battery is recorded as the right discharge cut-off voltage U r,D .
[0073] S23, discharge judgment 1: If the left discharge cut-off voltage U l,D Greater than or equal to the cut-off voltage U, and the right discharge cut-off voltage U r,D If the current interval is less than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left discharge test current I l,D , then the right end point of the current interval is updated to the right discharge test current I r,D , thereby forming a new current range.
[0074] Discharge judgment 2: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D If both are less than or equal to the cut-off voltage U, the left endpoint of the current interval remains unchanged, and the right endpoint of the current interval is updated to the left discharge test current I l,D , thereby forming a new current interval;
[0075] Discharge judgment three: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|>0.01V and |U r,D-U|>0.01V, the left end point of the current interval is updated to the right discharge test current I r,D , then keep the right end point of the current interval unchanged to form a new current interval;
[0076] Discharge judgment 4: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and / or |U r,D -U|≤0.01V, get the current limit current of the current SOC;
[0077] S24, when any one of the discharge judgments 1, 2 and 3 is met, the original current interval in step S21 is replaced with the obtained new current interval, and the battery is continuously discharged according to the contents of steps S21 to S23;
[0078] When the discharge judgment 4 is met, the current SOC limit current can be obtained, that is, at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and |U r,D -U|≤0.01V, the right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the current SOC limit current; at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V or |U r,D -U|≤0.01V, the left discharge cut-off voltage U l,D The corresponding left discharge test current I l,D Or right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the limiting current of the current SOC.
[0079] 3. Calculate the charging limit current.
[0080] Based on the battery parameters, during the battery charging process, the charging optimization method is used to calculate the charging limit current of each SOC. The details are as follows:
[0081] The specific process of calculating the charging limit current of each SOC using the charging optimization method is as follows: The specific process of calculating the charging limit current of each SOC using the charging optimization method is as follows:
[0082] S31, the current range of the current SOC is [Imin ,I max ], the cut-off time is t, and the cut-off voltage is U.
[0083] Based on the current interval [I min ,I max ]Calculate the left charging test current I l,C And right charging test current I r,C , I l,C =I min +0.382(I max -I min ), I r,C =I min +0.618(I max -I min ).
[0084] S32, using the left charging test current I respectively at the current SOC l,C Or right charging test current I r,C Charging cut-off time t.
[0085] Record the left charging test current I l,C During charging, the maximum voltage across the battery is recorded as the left charging cut-off voltage U l,C .
[0086] Record the right charging test current I r,C During charging, the maximum voltage across the battery is recorded as the right charging cut-off voltage U r,C .
[0087] S33, charging judgment 1: If the left charging cut-off voltage U l,C Less than or equal to the cut-off voltage U, and the right charging cut-off voltage U r,C If the current is greater than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left charging test current I l,C , then the right end point of the current interval is updated to the right charging test current I r,C , thereby forming a new current range.
[0088] Charging judgment 2: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C If both are greater than or equal to the cut-off voltage U, the right endpoint of the current interval is updated to the left charging test current I l,C , the left endpoint of the current interval remains unchanged, thus forming a new current interval;
[0089] Charging judgment three: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,CIf both are less than or equal to the cut-off voltage U, the right endpoint of the current interval remains unchanged, and the left endpoint of the current interval is updated to the right charging test current I r,C , thereby forming a new current interval;
[0090] Charging judgment 4: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and / or |UU r,C |≤0.01V, get the current limit current of the current SOC;
[0091] S34, when any one of the charging judgments 1, 2 and 3 is met, the original current interval in step S31 is replaced with the new current interval, and the battery is continuously charged according to the contents of steps S31 to S33;
[0092] When the charging judgment 4 is met, the current SOC limit current can be obtained, that is, at the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and |UU r,C |≤0.01V, the right charging cut-off voltage U r,C Corresponding right charging test current I r,C That is the current SOC limit current; at the left charging cut-off voltage U l and right charging cut-off voltage U r are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V or |UU r,C |≤0.01V, at this time the left charging cut-off voltage U l Corresponding left charging test current I l,C Or right charging cut-off voltage U r Corresponding right charging test current I r,C That is the limiting current of the current SOC.
[0093] Embodiment 1:
[0094] Select a 117.15Ah battery with a discharge cut-off time of 18s at 20% SOC, and detect what current can just meet the discharge requirement of 18s.
[0095] First discharge test: At 20% SOC, the initial current interval is [0,600], and the left discharge test current is selected as 229A and the right discharge test current is selected as 371A by the discharge optimization method, and the discharge is performed for 18s, and the cut-off voltage is set to 2.8V. The discharge results at this time are shown in Table 1.
[0096] Table 1 First discharge test results at 20% SOC
[0097]
[0098] It can be seen from Table 1 that the left discharge cut-off voltage and the right discharge cut-off voltage are both greater than the cut-off voltage of 2.8V, and the voltage errors are both greater than 0.01V, so a second discharge test is required.
[0099] Second discharge test: At this time, the current interval at 20% SOC is [371,600]. The discharge optimization method is used to select the left discharge test current of 458A and the right discharge test current of 522A. The discharge is carried out for 18s and the cut-off voltage is set to 2.8V. The discharge results at this time are shown in Table 2.
[0100] Table 2 Second discharge test results at 20% SOC
[0101]
[0102] It can be seen from Table 2 that the left discharge cut-off voltage and the right discharge cut-off voltage are both greater than the cut-off voltage of 2.8V, and the voltage errors are both greater than 0.01V, so a third discharge test is required.
[0103] The third discharge test:
[0104] The current interval at 20% SOC is [522,600], and the left discharge test current is selected as 552A and the right discharge test current is selected as 570A by the discharge optimization method, and the discharge is performed for 18s, and the cut-off voltage is set to 2.8V. The discharge results at this time are shown in Table 3.
[0105] Table 3 Results of the third discharge test at 20% SOC
[0106]
[0107] It can be seen from Table 3 that the left discharge cut-off voltage and the right discharge cut-off voltage are both greater than the cut-off voltage of 2.8V, and the voltage error corresponding to the right discharge cut-off voltage of 2.808V is less than 0.01V. Therefore, the right discharge test current of 570A at this time is the discharge limit current of the current battery.
[0108] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A method for finding the battery limiting current based on an optimization method, characterized in that: The following steps are involved: S1. Determine the SOC of the battery, as well as the cut-off time, cut-off voltage and current range corresponding to each SOC; S2. Based on the data in step S1, during the battery discharge process, the discharge limit current of each SOC is calculated using the discharge optimization method; S3. Based on the data in step S1, during the battery charging process, a charging optimization method is used to calculate the charging limit current of each SOC.
2. The method for finding the battery limiting current based on the optimization method according to claim 1, characterized in that: The process of calculating the discharge limit current for each SOC using the discharge optimization method is as follows: S21, the current range of the current SOC is [I min ,I max ], the cut-off time is t, the cut-off voltage is U; based on the current interval [I min ,I max ]Calculate the left discharge test current I l,D And right discharge test current I r,D ; S22, use the left discharge test current I respectively at the current SOC l,D Or right discharge test current I r,D Discharge cut-off time t; Record the left discharge test current I l,D During discharge, the maximum voltage across the battery is recorded as the left discharge cut-off voltage U l,D ; Record the discharge test current I r,D During discharge, the maximum voltage across the battery is recorded as the right discharge cut-off voltage U r,D ; S23. Formulate discharge judgment principles according to the discharge situation; the discharge judgment principles include discharge judgment one, discharge judgment two, discharge judgment three and discharge judgment four; S24, when any one of the discharge judgments 1, 2 and 3 is met, the original current interval in step S21 is replaced with the obtained new current interval, and the battery is continuously discharged according to the contents of steps S21 to S23; When the discharge judgment 4 is met, the current SOC limit current can be obtained, that is, at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and |U r,D -U|≤0.01V, the right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the current SOC limit current; at the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V or |U r,D -U|≤0.01V, the left discharge cut-off voltage U l,D The corresponding left discharge test current I l,D Or right discharge cut-off voltage U r,D The corresponding right discharge test current I r,D That is the limiting current of the current SOC.
3. The method for finding the battery limiting current based on the optimization method according to claim 2, characterized in that: Left discharge test current I l,D The calculation formula is as follows: I l,D =I min +0.382(I max -I min ); Right discharge test current I r,D The calculation formula is as follows: I r,D =I min +0.618(I max -I min )。 4. The method for finding the battery limiting current based on the optimization method according to claim 3, characterized in that: The discharge judgment principle is specifically expressed as follows: Discharge judgment 1: If the left discharge cut-off voltage U l,D Greater than or equal to the cut-off voltage U, and the right discharge cut-off voltage U r,D If the current interval is less than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left discharge test current I l,D , then the right end point of the current interval is updated to the right discharge test current I r,D , thereby forming a new current interval; Discharge judgment 2: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D If both are less than or equal to the cut-off voltage U, the left endpoint of the current interval remains unchanged, and the right endpoint of the current interval is updated to the left discharge test current I l,D , thereby forming a new current interval; Discharge judgment three: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|>0.01V and |U r,D -U|>0.01V, the left end point of the current interval is updated to the right discharge test current I r,D , then keep the right end point of the current interval unchanged to form a new current interval; Discharge judgment 4: If the left discharge cut-off voltage U l,D And right discharge cut-off voltage U r,D are greater than or equal to the cut-off voltage U, and |U l,D -U|≤0.01V and / or |U r,D -U|≤0.01V, get the current limit current of the current SOC; 5. A method for finding the battery limiting current based on an optimization method according to any one of claims 1 to 4, characterized in that: The specific process of calculating the charging limit current of each SOC using the charging optimization method is as follows: The specific process of calculating the charging limit current of each SOC using the charging optimization method is as follows: S31, the current range of the current SOC is [I min ,I max ], the cut-off time is t, the cut-off voltage is U; based on the current interval [I min ,I max ]Calculate the left charging test current I l,C And right charging test current I r,C ; S32, using the left charging test current I respectively at the current SOC l,C Or right charging test current I r,C Charging cut-off time t; Record the left charging test current I l,C During charging, the maximum voltage across the battery is recorded as the left charging cut-off voltage U l,C ; Record the right charging test current I r,C During charging, the maximum voltage across the battery is recorded as the right charging cut-off voltage U r,C ; S33. Formulate charging judgment principles according to the charging situation; the charging judgment principles include charging judgment 1, charging judgment 2, charging judgment 3 and charging judgment 4; S34, when any one of the charging judgments 1, 2 and 3 is met, the original current interval in step S31 is replaced with the new current interval, and the battery is continuously charged according to the contents of steps S31 to S33; When the charging judgment 4 is met, the current SOC limit current can be obtained, that is, at the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and |UU r,C |≤0.01V, the right charging cut-off voltage U r,C Corresponding right charging test current I r,C That is the current SOC limit current; at the left charging cut-off voltage U l and right charging cut-off voltage U r are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V or |UU r,C |≤0.01V, at this time the left charging cut-off voltage U l Corresponding left charging test current I l,C Or right charging cut-off voltage U r Corresponding right charging test current I r,C That is the limiting current of the current SOC.
6. The method for finding the battery limiting current based on the optimization method according to claim 5, characterized in that: Left charging test current I l,C The calculation formula is as follows: I l,C =I min +0.382(I max -I min ); Right charging test current I r,C The calculation formula is as follows: I r,C =I min +0.618(I max -I min )。 7. The method for finding the battery limiting current based on the optimization method according to claim 6, characterized in that: The charging judgment principles are as follows: Charging judgment 1: If the left charging cut-off voltage U l,C Less than or equal to the cut-off voltage U, and the right charging cut-off voltage U r,C If the current is greater than or equal to the cut-off voltage U, the left end point of the current interval is updated to the left charging test current I l,C , then the right end point of the current interval is updated to the right charging test current I r,C , thereby forming a new current interval; Charging judgment 2: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C If both are greater than or equal to the cut-off voltage U, the right end point of the current interval is updated to the left charging test current I l,C , the left endpoint of the current interval remains unchanged, thus forming a new current interval; Charging judgment three: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C If both are less than or equal to the cut-off voltage U, the right endpoint of the current interval remains unchanged, and the left endpoint of the current interval is updated to the right charging test current I r,C , thereby forming a new current interval; Charging judgment 4: If the left charging cut-off voltage U l,C and right charging cut-off voltage U r,C are less than or equal to the cut-off voltage U, and |UU l,C |≤0.01V and / or |UU r,C |≤0.01V, get the current limit current of the current SOC; 8. The method for finding the battery limiting current based on the optimization method according to claim 7, characterized in that: The specific steps of step S1 are as follows: S11, determine the SOC of the battery; divide the SOC range from 0% to 100% into 5 equally spaced intervals, [0%, 20%], [20%, 40%], [40%, 60%], [60%, 80%], [80%, 100%]; S12, determining the cut-off time corresponding to each SOC: according to each interval divided in step S1, determining the time required to fill the SOC of the interval or discharge the SOC of the interval, which is the cut-off time of the interval; S13, determining the cut-off voltage corresponding to each SOC: measuring and obtaining the highest voltage value allowed to be reached during charging or discharging in each interval in step S1, and the highest voltage value is the cut-off voltage corresponding to the interval; S14, determining the current interval corresponding to each SOC: measuring the minimum current value or the maximum current value during the charging process or the discharging process in each interval, and the interval formed by the minimum current value and the maximum current value is the current interval of the interval.