Power battery self-discharge monitoring method and system, vehicle and electronic equipment

Abstract

The invention relates to a power battery self-discharge monitoring method and system, a vehicle and electronic equipment. The method comprises the following steps: when the power battery is fully charged and is powered off to a first time, acquiring a first voltage, a first accumulative charging capacity and a first environment temperature of a single cell of the battery; acquiring a second voltage, a second environment temperature and a first calendar life when the power battery is fully charged and powered down to a second time; obtaining a first initial average self-discharge current, the number of charge-discharge cycles after full charge and a first average environment temperature according to the obtained parameters; correcting the first initial average self-discharge current to obtain a first real average self-discharge current; and when the first real average self-discharge current is greater than a preset fault self-discharge current threshold value, self-discharge abnormity is alarmed. The invention also provides a system for realizing the self-discharge monitoring method of the power battery. The invention further provides electronic equipment and a vehicle. The problem that an existing power battery self-discharge early warning method is low in accuracy is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery safety, and particularly relates to a method and system for monitoring the self-discharge of a power battery, a vehicle, and an electronic device. Background Art

[0002] In recent years, with the transformation of the global energy structure and the improvement of environmental awareness, the electric vehicle market has shown an explosive growth trend. As the core component of electric vehicles, the performance of power batteries is directly related to the safety, driving range, and service life of the entire vehicle. Among them, lithium-ion batteries have become the mainstream technical route for power batteries due to their advantages such as high energy density and long cycle life. However, the problem of lithium dendrite growth during the long-term use of lithium-ion batteries has always been the key technical bottleneck restricting their safety performance.

[0003] The formation mechanism of lithium dendrites is mainly related to the transport characteristics of lithium ions during the charge and discharge process. Under ideal conditions, lithium ions should be evenly embedded in the negative electrode material. However, in actual use, due to factors such as the inhomogeneity of the electrode material, the difference in electrolyte distribution, and the uneven temperature field distribution, the transport path of lithium ions may be blocked. When lithium ions cannot be normally embedded in the negative electrode, they will precipitate on the surface of the negative electrode, forming dendritic crystals, that is, lithium dendrites. The growth of these lithium dendrites will bring multiple negative impacts: First, lithium dendrites will consume active lithium, resulting in a decrease in battery capacity; second, lithium dendrites will increase the internal resistance of the battery and reduce the energy conversion efficiency; more seriously, the continuously growing lithium dendrites may pierce the separator, causing a direct short circuit between the positive and negative electrodes and triggering safety accidents such as thermal runaway.

[0004] The existence of lithium dendrites will also cause micro-short circuits inside the battery. Although this kind of micro-short circuit will not immediately trigger serious safety accidents, it will cause continuous self-discharge of the battery. The abnormal increase in the self-discharge rate is often an early sign of micro-short circuits inside the battery. Therefore, accurately monitoring the self-discharge rate of power batteries is of great significance for preventing safety accidents. At present, the industry generally uses the voltage drop amplitude of a single battery cell within a certain period of time to judge the self-discharge rate. This method is relatively effective for battery types with obvious voltage change characteristics (such as ternary lithium batteries). However, for lithium iron phosphate batteries, due to their unique voltage characteristics, they are often in a voltage plateau period under normal use conditions, resulting in great limitations in the method of judging the self-discharge rate by voltage changes.

[0005] In the prior art, a method for warning of battery self-discharge faults is disclosed. This method identifies self-discharge faults by collecting historical data (including single-cell voltage and time information) of the battery in the most recent N days, and triggers a warning when a fault is detected. Although this method can achieve self-discharge monitoring to a certain extent, it mainly relies on the collection of voltage data during vehicle use, which has obvious deficiencies for lithium iron phosphate batteries: First, the single-cell voltage during vehicle use is usually in the voltage plateau period of the lithium iron phosphate battery, and the voltage change is not obvious, making it difficult to accurately reflect the self-discharge situation; Second, factors such as temperature fluctuations and changes in charge and discharge states during use will interfere with the accuracy of voltage data; Finally, this method cannot effectively distinguish between voltage fluctuations during normal use and voltage changes caused by self-discharge, and is prone to misjudgment.

[0006] Therefore, developing a method that can accurately monitor the self-discharge rate of lithium iron phosphate batteries, especially a technical solution for accurately monitoring batteries in a static state after full charge, has important practical significance for improving the safety performance of power batteries. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a method, system, vehicle and electronic device for monitoring the self-discharge of power batteries, so as to solve the problems of low accuracy of the existing power battery self-discharge warning method and inapplicability to the self-discharge monitoring of lithium iron phosphate batteries.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A method for monitoring the self-discharge of a power battery includes the following steps:

[0010] S1. When the power battery is fully charged and discharged to the first time, obtain the first voltage, the first cumulative charge capacity and the first ambient temperature of the battery single cell;

[0011] S2. When the power battery is fully charged and discharged to the second time, obtain the second voltage, the second ambient temperature and the first calendar life of the battery single cell, where the second time is greater than 2 times the first time;

[0012] S3. According to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charge capacity, the first ambient temperature and the second ambient temperature, obtain the first initial average self-discharge current, the number of charge and discharge cycles after full charge and the first average ambient temperature of the battery single cell;

[0013] S4. Correct the first initial average self-discharge current through the number of charge and discharge cycles after full charge, the first calendar life, the maximum capacity attenuation rate and the cell capacity at the first average ambient temperature to obtain the first true average self-discharge current;

[0014] S5. When the first true average self-discharge current is greater than the preset fault self-discharge current threshold, an alarm for abnormal self-discharge is given.

[0015] According to the above technical means, by obtaining multi-dimensional data such as the voltage, cumulative charge capacity, ambient temperature, and calendar life of a single battery cell at different time points, and using the OCV-SOC curve to determine the true state of charge (SOC) of the battery, the error caused by simply relying on voltage or capacity to calculate the initial average self-discharge current is avoided. Further, by combining factors such as the number of charge-discharge cycles after full charge, calendar life, maximum capacity decay rate, and cell capacity at the average ambient temperature, the initial average self-discharge current is corrected to obtain a more realistic average self-discharge current, improving the accuracy of early warning. Thus, the problem of low accuracy existing in the existing self-discharge early warning method for power batteries is effectively solved.

[0016] Preferably, the calculation method of the first initial average self-discharge current is as follows:

[0017] According to the first voltage and the OCV-SOC curve, the first true remaining charge of the single battery cell is obtained, and then combined with the rated capacity, the first true capacity of the single battery cell is calculated;

[0018] According to the second voltage and the OCV-SOC curve, the second true remaining charge of the single battery cell is obtained, and then combined with the rated capacity, the second true capacity of the single battery cell is calculated;

[0019] According to the first true capacity and the second true capacity, the first self-discharge capacity decay of the single battery cell is obtained, and then combined with the first time and the second time, the first initial average self-discharge current is calculated.

[0020] Preferably, the calculation method of the number of charge-discharge cycles after full charge is as follows:

[0021] According to the first cumulative charge capacity and the rated capacity, the number of charge-discharge cycles after full charge is calculated;

[0022] The first cumulative charge capacity includes the first cumulative external charging capacity and the first cumulative energy recovery capacity.

[0023] Preferably, the calculation method of the first average ambient temperature is as follows:

[0024] According to the first ambient temperature and the second ambient temperature, the first average ambient temperature is calculated.

[0025] Preferably, the calculation formula for the first true capacity of the single battery cell is:

[0026] P 1 = SOC 1 × P(V1)

[0027] In formula (V1), SOC 1 represents the first true remaining capacity of the battery single cell, in Ah, P represents the rated capacity of the battery single cell, in Ah, P 1 represents the first true capacity of the battery single cell, in Ah;

[0028] And / or, the calculation formula for the second true capacity of the battery single cell is:

[0029] P 2 = SOC 2 × P(V2)

[0030] In formula (V2), SOC 2 represents the second true remaining capacity of the battery single cell, in Ah, P represents the rated capacity of the battery single cell, in Ah, P 2 represents the second true capacity of the battery single cell, in Ah.

[0031] Preferably, the calculation formula for the first self-discharge capacity attenuation of the battery single cell is:

[0032] ΔP 1 = P 1 - P 2 (V3)

[0033] In formula (V3), P 1 represents the first true capacity of the battery single cell, in Ah, P 2 represents the second true capacity of the battery single cell, in Ah, ΔP 1 represents the first self-discharge capacity attenuation of the battery single cell, in Ah;

[0034] The calculation formula for the first initial average self-discharge current is:

[0035] I p1 = ΔP 1 / (t 2 - t 1 )(V4)

[0036] In formula (V4), ΔP 1 represents the first self-discharge capacity attenuation of the battery single cell, in Ah, t 1 represents the first time, in h, t 2 represents the second time, in h; I p1 represents the first initial average self-discharge current of the battery single cell, in A.

[0037] Preferably, the calculation formula for the number of charge-discharge cycles after full charge is:

[0038] C 1 = (Q 1 + Q 2 ) / P(V5)

[0039] In formula (V5), Q 1 represents the first cumulative external charging capacity of a single battery cell, in Ah, Q 2 represents the first cumulative energy recovery capacity of a single battery cell, in Ah, P represents the rated capacity of a single battery cell, in Ah, C 1 represents the number of charge-discharge cycles after a single battery cell is fully charged.

[0040] Preferably, the calculation formula for the first average ambient temperature is:

[0041] T p1 = (T 1 + T 2 ) / 2(V6)

[0042] In formula (V6), T 1 represents the first ambient temperature, in °C, T 2 represents the second ambient temperature, in °C, T p1 represents the first average ambient temperature, in °C.

[0043] Preferably, the calculation formula for the first true average self-discharge current is:

[0044] I x1 = I p1 × K T1 × (K C1 + K L1 ) / 2(V7)

[0045] In formula (V7), I p1 represents the first initial average self-discharge current of a single battery cell, in A, K T1 represents the first temperature correction coefficient, K C1 represents the first cycle number correction coefficient, K L1 represents the first calendar life correction coefficient, I x1 represents the first true average self-discharge current of a single battery cell, in A;

[0046] Among them, the calculation formula for K T1 is:

[0047] K T1 = P b / P a (V8)

[0048] In formula (V8), P b represents the capacity of a single battery cell at the first average ambient temperature, in Ah, Pa Indicates the single-cell capacity of the battery at room temperature, with the unit of Ah, K T1 Indicates the first temperature correction coefficient;

[0049] Among them, the single-cell capacity P of the battery at room temperature a and the single-cell capacity P of the battery at the second average ambient temperature b are obtained by referring to the corresponding relationship table between temperature and the single-cell capacity of the battery;

[0050] K C1 The calculation formula of is:

[0051] K C1 = 1 - (η max / C s ) × C 1 (V9)

[0052] In formula (V9), η max Indicates the maximum capacity attenuation rate of the single cell of the battery under the preset number of cycles, C s Indicates the preset number of cycles, C 1 Indicates the number of charge-discharge cycles after full charge, K C1 Indicates the first cycle number correction coefficient;

[0053] K L1 The calculation formula of is:

[0054] K L1 = 1 - (η max / K s ) × L 1 (V10)

[0055] In formula (V10), η max Indicates the maximum capacity attenuation rate of the single cell of the battery under the preset number of cycles, K s Indicates the preset calendar life, L 1 Indicates the first calendar life, K L1 Indicates the first calendar life correction coefficient.

[0056] Preferably, it further includes the following steps:

[0057] S6. When the power battery is fully charged and discharged to the first time again, according to the methods of S1 to S4, obtain the third voltage, fourth voltage, second cumulative charge capacity, second initial average self-discharge current, number of charge-discharge cycles after the second full charge, second average ambient temperature and second true average self-discharge current of the single cell of the battery;

[0058] S7. According to the first cumulative charge capacity and the second cumulative charge capacity, obtain the increment of the cumulative charge capacity, and according to the first true average self-discharge current and the second true average self-discharge current, obtain the increment of the true average self-discharge current;

[0059] S8. Obtain the change rate of the self-discharge rate based on the increment of the cumulative charged capacity and the increment of the true average self-discharge current.

[0060] S9. When the change rate of the self-discharge rate is greater than the change rate of the preset fault self-discharge rate, alarm for abnormal self-discharge.

[0061] After the power battery is fully charged and discharged again, obtain the second cumulative charged capacity and the second true average self-discharge current of the battery single cell, and combine the first cumulative charged capacity and the first true average self-discharge current after the previous full charge and discharge, obtain the increment of the cumulative charged capacity and the increment of the true average self-discharge current, and then calculate the change rate of the self-discharge rate to judge the abnormal situation of the battery self-discharge, so as to dynamically reflect the change trend of the battery self-discharge behavior, thus discovering the abnormal change of the battery self-discharge behavior earlier, further improving the accuracy of the power battery self-discharge warning, and effectively avoiding the further deterioration of the battery performance.

[0062] Preferably, in the said S6, it includes the following steps:

[0063] S61. When the power battery is fully charged and discharged again to the first time, obtain the third voltage, the second cumulative charged capacity and the third ambient temperature of the battery single cell.

[0064] S62. When the power battery is fully charged and discharged again to the second time, obtain the fourth voltage, the fourth ambient temperature and the second calendar life of the battery single cell.

[0065] S63. Based on the third voltage, the fourth voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the second cumulative charged capacity, the third ambient temperature and the fourth ambient temperature, obtain the second initial average self-discharge current, the number of charge and discharge cycles after the full charge again and the second average ambient temperature of the battery single cell.

[0066] S64. Correct the second initial average self-discharge current through the number of charge and discharge cycles after the full charge again, the second calendar life, the maximum capacity attenuation rate and the cell capacity at the second average ambient temperature to obtain the second true average self-discharge current.

[0067] Preferably, the calculation method of the said second initial average self-discharge current is:

[0068] Based on the third voltage and the OCV-SOC curve, obtain the third true remaining power of the battery single cell, and then combine the rated capacity to calculate the third true capacity of the battery single cell.

[0069] According to the fourth voltage and the OCV-SOC curve, the fourth true remaining capacity of the single battery cell is obtained, and then combined with the rated capacity, the fourth true capacity of the single battery cell is calculated;

[0070] According to the third true capacity and the fourth true capacity, the second self-discharge capacity attenuation of the single battery cell is obtained, and then combined with the first time and the second time, the second initial average self-discharge current is calculated.

[0071] Preferably, the calculation method of the number of charge-discharge cycles after the re-full charge is as follows:

[0072] According to the second cumulative charge capacity and the rated capacity, the number of charge-discharge cycles after the re-full charge is calculated;

[0073] The second cumulative charge capacity includes the second cumulative external charging capacity and the second cumulative energy recovery capacity.

[0074] Preferably, the calculation method of the second average ambient temperature is as follows:

[0075] According to the third ambient temperature and the fourth ambient temperature, the second average ambient temperature is calculated.

[0076] Preferably, the calculation formula for the third true capacity of the single battery cell is:

[0077] P 3 =SOC 3 ×P(V11)

[0078] In formula (V11), SOC 3 represents the third true remaining capacity of the single battery cell, in Ah, P represents the rated capacity of the single battery cell, in Ah, P 3 represents the third true capacity of the single battery cell, in Ah;

[0079] And / or, the calculation formula for the fourth true capacity of the single battery cell is:

[0080] P 4 =SOC 4 ×P(V12)

[0081] In formula (V12), SOC 4 represents the fourth true remaining capacity of the single battery cell, in Ah, P represents the rated capacity of the single battery cell, in Ah, P 4 represents the fourth true capacity of the single battery cell, in Ah.

[0082] Preferably, the calculation formula for the second self-discharge capacity attenuation of the single battery cell is:

[0083] ΔP 2 =P3 -P 4 (V13)

[0084] In formula (V13), P 3 represents the third true capacity of a single battery cell, in Ah, P 4 represents the fourth true capacity of a single battery cell, in Ah, ΔP 2 represents the second self-discharge capacity attenuation of a single battery cell, in Ah;

[0085] The calculation formula for the second initial average self-discharge current is:

[0086] I p2 = ΔP 2 / (t 2 -t 1 )(V14)

[0087] In formula (V14), ΔP 2 represents the second self-discharge capacity attenuation of a single battery cell, in Ah, t 1 represents the first time, in h, t 2 represents the second time, in h; I p2 represents the second initial average self-discharge current of a single battery cell, in A.

[0088] Preferably, the calculation formula for the number of charge-discharge cycles after re-full charge is:

[0089] C 2 =(Q 3 +Q 4 ) / P(V15)

[0090] In formula (V15), Q 3 represents the second cumulative external charging capacity of a single battery cell, in Ah, Q 4 represents the second cumulative energy recovery capacity of a single battery cell, in Ah, P represents the rated capacity of a single battery cell, in Ah, C 2 represents the number of charge-discharge cycles after re-full charge.

[0091] Preferably, the calculation formula for the second average ambient temperature is:

[0092] T p2 =(T 3 +T 4 ) / 2(V16)

[0093] In formula (V16), T 3 represents the third ambient temperature, in °C, T 4 represents the fourth ambient temperature, in °C, T p2Represents the second average ambient temperature, in °C.

[0094] Preferably, the calculation formula for the second true average self-discharge current is:

[0095] I x2 = I p2 × K T2 × (K C2 + K L2 ) / 2 (V17)

[0096] In formula (V17), I p2 represents the second initial average self-discharge current of the battery single cell, in A, K T2 represents the second temperature correction coefficient, K C2 represents the second cycle number correction coefficient, K L2 represents the second calendar life correction coefficient, I x2 represents the second true average self-discharge current of the battery single cell, in A.

[0097] Among them, the calculation formula for K T2 is:

[0098] K T2 = P c / P a (V18)

[0099] In formula (V18), P c represents the capacity of the battery single cell at the second average ambient temperature, in Ah, P a represents the capacity of the battery single cell at room temperature, in Ah, K T2 represents the second temperature correction coefficient.

[0100] The calculation formula for K C2 is:

[0101] K C2 = 1 - (η max / C s ) × C 2 (V19)

[0102] In formula (V19), η max represents the maximum capacity attenuation rate of the battery single cell under the preset number of cycles, C s represents the preset number of cycles, C 2 represents the number of charge and discharge cycles after being fully charged again, K C2 represents the second cycle number correction coefficient.

[0103] The calculation formula for K L2 is:

[0104] K L2= 1 - (η max / K s ) × L 2 (V20)

[0105] In formula (V20), η max represents the maximum capacity attenuation rate of a single battery cell under a preset number of cycles, K s represents the preset calendar life, L 2 represents the second calendar life, and K L2 represents the correction factor for the second calendar life.

[0106] Preferably, the calculation formula for the increment of the cumulative charged capacity is:

[0107] ΔQ = (Q 3 + Q 4 ) - (Q 1 + Q 2 )(V21)

[0108] In formula (V21), Q 3 represents the second cumulative external charging capacity of a single battery cell, in Ah, Q 4 represents the second cumulative energy recovery capacity of a single battery cell, in Ah, Q 1 represents the first cumulative external charging capacity of a single battery cell, in Ah, Q 2 represents the first cumulative energy recovery capacity of a single battery cell, in Ah, and ΔQ represents the increment of the cumulative charged capacity of a single battery cell, in Ah.

[0109] Preferably, the calculation formula for the increment of the true average self-discharge current is:

[0110] ΔI = I x2 - I x1 (V22)

[0111] In formula (V22), I x2 represents the second true average self-discharge current of a single battery cell, in A, I x1 represents the first true average self-discharge current of a single battery cell, in A, and ΔI represents the increment of the true average self-discharge current of a single battery cell, in A;

[0112] Preferably, the calculation formula for the change rate of the self-discharge rate is:

[0113] Δσ = ΔI / ΔQ (V23)

[0114] In formula (V23), ΔI represents the increment of the true average self-discharge current of a single battery cell, in Ah, ΔQ represents the increment of the cumulative charged capacity of a single battery cell, in Ah, and Δσ represents the change rate of the self-discharge rate of a single battery cell, in h-1 。

[0115] The present invention also provides a system for implementing the method for monitoring the self-discharge of a power battery as described in the present invention, including:

[0116] A data acquisition module, configured to obtain the first voltage, the first cumulative charge capacity, and the first ambient temperature of a single battery cell when the power battery is fully charged and discharged to the first time; and configured to obtain the second voltage, the second ambient temperature, and the first calendar life of the single battery cell when the power battery is fully charged and discharged to the second time, where the second time is greater than 2 times the first time;

[0117] A self-discharge current calculation module, configured to obtain the first initial average self-discharge current, the number of charge and discharge cycles after full charge, and the first average ambient temperature of the single battery cell according to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charge capacity, the first ambient temperature, and the second ambient temperature;

[0118] A self-discharge current correction module, configured to correct the first initial average self-discharge current through the number of charge and discharge cycles after full charge, the first calendar life, the maximum capacity decay rate, and the cell capacity at the first average ambient temperature to obtain the first true average self-discharge current;

[0119] An abnormal alarm module, configured to alarm abnormal self-discharge when the first true average self-discharge current is greater than a preset fault self-discharge current threshold.

[0120] The present invention also provides an electronic device, including a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the method for monitoring the self-discharge of a power battery as described in the present invention when executing the computer program.

[0121] The present invention also provides a vehicle, where the vehicle includes the electronic device as described in the present invention.

[0122] Advantages of the present invention:

[0123] The method for monitoring the self-discharge of a power battery according to the present invention obtains multi-dimensional data such as the voltage, cumulative charge capacity, ambient temperature, and calendar life of a single battery cell at different time points, and uses the OCV-SOC curve to determine the true state of charge (SOC) of the battery, avoiding the error caused by simply relying on voltage or capacity to calculate the initial average self-discharge current. Further, by combining factors such as the number of charge and discharge cycles, calendar life, maximum capacity decay rate, and cell capacity at the average ambient temperature of the power battery, the initial average self-discharge current is corrected to obtain a more real average self-discharge current, improving the accuracy of early warning. Thus, the problem of low accuracy existing in the existing method for early warning of self-discharge of power batteries is effectively solved.

[0124] The self-discharge monitoring method for power batteries of the present invention not only considers the voltage change of a single battery cell but also combines multiple factors such as the cumulative charge capacity, ambient temperature, and calendar life to achieve comprehensive monitoring of the self-discharge situation of power batteries. This helps to promptly detect changes in battery performance and prevent potential safety hazards. When the calculated true average self-discharge current exceeds the preset fault self-discharge current threshold, the method can immediately issue an alarm signal to indicate abnormal self-discharge. Thus, it helps to promptly detect and handle the self-discharge problem of power batteries, avoid further deterioration of battery performance, and ensure the safe operation of the battery system. It has the value of popularization and application in the field of vehicle battery safety technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0125] Figure 1 It is the first flow chart of the self-discharge monitoring method for power batteries of the present invention;

[0126] Figure 2 It is the structural schematic diagram of the hardware involved in the self-discharge monitoring method for power batteries of the present invention;

[0127] Figure 3 It is the second flow chart of the self-discharge monitoring method for power batteries of the present invention;

[0128] Figure 4 It is the flow chart for determining the second cumulative charge capacity and the second true average self-discharge current;

[0129] Figure 5 It is the structural schematic diagram of the system for the self-discharge monitoring method of power batteries;

[0130] Figure 6 It is the structural schematic diagram of an electronic device;

[0131] Among them, 1 - data acquisition module; 2 - self-discharge current calculation module; 3 - self-discharge current correction module; 4 - abnormal alarm module; 5 - vehicle controller; 6 - battery management system; 7 - T-BOX; 8 - big data cloud platform; 9 - memory; 10 - processor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0132] The following will describe the embodiments of the present invention with reference to the drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for explaining the present invention and not for limiting the protection scope of the present invention.

[0133] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0134] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present application. However, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details.

[0135] The present invention aims to disclose a method, system, vehicle, and electronic device for monitoring the self-discharge of power batteries, so as to solve the problems of low accuracy in the existing power battery self-discharge warning method and inapplicability to the self-discharge monitoring of lithium iron phosphate batteries.

[0136] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0137] As Figure 1 shown, a method for monitoring the self-discharge of a power battery includes the following steps:

[0138] S1. When the power battery is fully charged and discharged to the first time, obtain the first voltage, the first cumulative charge capacity, and the first ambient temperature of the single battery cell.

[0139] S2. When the power battery is fully charged and discharged to the second time, obtain the second voltage, the second ambient temperature, and the first calendar life of the single battery cell, where the second time is greater than 2 times the first time.

[0140] S3. According to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charge capacity, the first ambient temperature, and the second ambient temperature, obtain the first initial average self-discharge current of the single battery cell, the number of charge and discharge cycles after full charge, and the first average ambient temperature.

[0141] S4. Correct the first initial average self-discharge current through the number of charge and discharge cycles after full charge, the first calendar life, the maximum capacity attenuation rate, and the cell capacity at the first average ambient temperature to obtain the first true average self-discharge current.

[0142] S5. When the first true average self-discharge current is greater than the preset fault self-discharge current threshold, alarm for abnormal self-discharge.

[0143] By obtaining multi-dimensional data such as the voltage, cumulative charge capacity, ambient temperature, and calendar life of a single battery cell at different time points, and using the OCV-SOC curve to determine the true state of charge (SOC) of the battery, the error caused by simply relying on voltage or capacity to calculate the initial average self-discharge current is avoided. Further, by combining factors such as the charge-discharge cycle times, calendar life, maximum capacity attenuation rate, and cell capacity at the average ambient temperature of the power battery, the initial average self-discharge current is corrected to obtain a more realistic average self-discharge current, improving the accuracy of early warning.

[0144] The method of the present invention not only considers the voltage change of a single battery cell, but also combines multiple factors such as cumulative charge capacity, ambient temperature, and calendar life, realizing comprehensive monitoring of the self-discharge of power batteries. This helps to timely detect changes in battery performance and prevent potential safety hazards. Among them, by considering the influence of ambient temperature on battery self-discharge, the monitoring requirements under different temperature conditions can be adapted; by correcting the self-discharge current through the charge-discharge cycle times and calendar life, the change in the self-discharge characteristics of the battery at different usage stages can be adapted; by limiting the second time to be greater than twice the first time, the self-discharge behavior of the battery over a long period of time can be captured, and potential problems can be detected in advance; by correcting in combination with the maximum capacity attenuation rate, the trend of battery performance degradation can be detected earlier.

[0145] When the calculated true average self-discharge current exceeds the preset fault self-discharge current threshold, the method can immediately send an alarm signal to indicate abnormal self-discharge. This helps to timely detect and handle the self-discharge problem of power batteries, avoid further deterioration of battery performance, and ensure the safe operation of the battery system.

[0146] The above method is applicable to different types of power batteries, including lithium-ion batteries, lead-acid batteries, etc., and is particularly suitable for monitoring the self-discharge abnormality of lithium iron phosphate batteries. Because the above method overcomes the limitations of existing monitoring methods in the application of lithium iron phosphate batteries, provides a more accurate and reliable self-discharge rate monitoring means, and thus provides a strong guarantee for the safe use of power batteries. At the same time, by adjusting the preset fault self-discharge current threshold, the requirements under different application scenarios can be adapted, improving the flexibility and applicability of the method.

[0147] As Figure 2 shown, the hardware involved in the above power battery self-discharge monitoring method includes a vehicle control unit (VCU) 5, a battery management system (BCU) 6, an in-vehicle remote terminal T-BOX 7, and a big data cloud platform 8. The vehicle control unit (VCU) 5, the battery management system (BCU) 6, the in-vehicle remote terminal T-BOX 7, and the big data cloud platform 8 are connected by a CAN wire harness.

[0148] Exemplarily, for the power battery on a vehicle, a complete power battery assembly is usually formed by connecting multiple battery single cells in series. Taking a certain battery single cell as an example, the power battery self-discharge monitoring method is as follows: after the vehicle is fully charged for the nth time (n represents the full charge times of the power battery, n≥1) and then powers off and enters the sleep state (the main positive relay of the power battery is disconnected), the battery management system BCU starts timing internally and performs the following steps:

[0149] S1. When it is recognized that the power battery of the vehicle is fully charged and powers off to the first time, and the power battery has not been under high voltage within the first time, the power battery BMS is woken up for the first time at low voltage. Specifically, the battery management system 6 wakes up the vehicle controller 5, obtains the first voltage, the first cumulative charge capacity, and the first ambient temperature of the battery single cell stored in the vehicle controller 5 at this time, uploads the obtained data to the cloud through the in-vehicle remote terminal T-BOX 7 and stores it in the database of the big data cloud platform 8. After the upload is completed, all the vehicle controllers power off and enter the sleep state;

[0150] S2. After the first data upload and entering the sleep state, the battery management system 6 starts timing internally again. When it is recognized that the power battery of the vehicle is fully charged and powers off to the second time, and the power battery has not been under high voltage during the period from the first time to the second time, the power battery BMS is woken up for the second time at low voltage. Specifically, the battery management system 6 wakes up the vehicle controller 5 again, obtains the second voltage, the second ambient temperature, and the first calendar life of the battery single cell stored in the vehicle controller 5 at this time, uploads the obtained data to the cloud through the in-vehicle remote terminal T-BOX 7 and stores it in the database of the big data cloud platform 8. After the upload is completed, all the vehicle controllers power off and enter the sleep state. To ensure the accuracy of subsequent self-discharge rate calculation, the time t2 should be as long as possible, and the second time is at least greater than 2 times the first time;

[0151] S3. In the cloud, based on the uploaded first voltage, second voltage, OCV-SOC curve, rated capacity, first time, second time, first cumulative charge capacity, first ambient temperature, and second ambient temperature, obtain the first initial average self-discharge current, the charge and discharge cycle times after full charge, and the first average ambient temperature of the battery single cell;

[0152] S4. Correct the first initial average self-discharge current through the charge and discharge cycle times after full charge, the first calendar life, the maximum capacity attenuation rate, and the cell capacity at the first average ambient temperature to obtain the first true average self-discharge current;

[0153] S5. When the first true average self-discharge current is greater than the preset fault self-discharge current threshold, an alarm for abnormal self-discharge is given.

[0154] Exemplarily, the first time is the relaxation and static time for full charge of a single battery cell, to ensure that after the power battery is fully charged and static for the first time, the actual voltage of the single battery cell is infinitely close to the static voltage of the single battery cell. The preset fault self-discharge current threshold is the minimum self-discharge current of the single battery cell, and the minimum self-discharge currents of different material systems are different.

[0155] In some embodiments, the calculation method of the first initial average self-discharge current is as follows:

[0156] According to the first voltage and the OCV-SOC curve, the first true remaining power of the single battery cell is obtained, and then combined with the rated capacity, the first true capacity of the single battery cell is calculated;

[0157] According to the second voltage and the OCV-SOC curve, the second true remaining power of the single battery cell is obtained, and then combined with the rated capacity, the second true capacity of the single battery cell is calculated;

[0158] According to the first true capacity and the second true capacity, the first self-discharge capacity attenuation of the single battery cell is obtained, and then combined with the first time and the second time, the first initial average self-discharge current is calculated.

[0159] Among them, the OCV-SOC curve is the OCV-SOC curve of the single battery cell, which is obtained through experimental tests.

[0160] In some embodiments, the calculation method of the number of charge and discharge cycles after full charge is as follows:

[0161] According to the first cumulative charged capacity and the rated capacity, the number of charge and discharge cycles after full charge is calculated;

[0162] The first cumulative charged capacity includes the first cumulative external charging capacity and the first cumulative energy recovery capacity;

[0163] And / or, the calculation method of the first average ambient temperature is as follows:

[0164] According to the first ambient temperature and the second ambient temperature, the first average ambient temperature is calculated.

[0165] In some embodiments, the calculation formula of the first true capacity of the single battery cell is:

[0166] P 1 =SOC 1 ×P(V1)

[0167] In formula (V1), SOC 1 represents the first true remaining power of the single battery cell, with the unit of Ah, P represents the rated capacity of the single battery cell, with the unit of Ah, and P 1 represents the first true capacity of the single battery cell, with the unit of Ah.

[0168] In some embodiments, the calculation formula for the second true capacity of a single battery cell is:

[0169] P 2 = SOC 2 × P(V2)

[0170] In formula (V2), SOC 2 represents the second true remaining power of the single battery cell, with the unit of Ah, P represents the rated capacity of the single battery cell, with the unit of Ah, and P 2 represents the second true capacity of the single battery cell, with the unit of Ah.

[0171] In some embodiments, the calculation formula for the first self-discharge capacity attenuation of a single battery cell is:

[0172] ΔP 1 = P 1 - P 2 (V3)

[0173] In formula (V3), P 1 represents the first true capacity of the single battery cell, with the unit of Ah, P 2 represents the second true capacity of the single battery cell, with the unit of Ah, and ΔP 1 represents the first self-discharge capacity attenuation of the single battery cell, with the unit of Ah;

[0174] The calculation formula for the first initial average self-discharge current is:

[0175] I p1 = ΔP 1 / (t 2 - t 1 )(V4)

[0176] In formula (V4), ΔP 1 represents the first self-discharge capacity attenuation of the single battery cell, with the unit of Ah, t 1 represents the first time, with the unit of h, and t 2 represents the second time, with the unit of h; I p1 represents the first initial average self-discharge current of the single battery cell, with the unit of A.

[0177] In some embodiments, the calculation formula for the number of charge-discharge cycles after full charge is:

[0178] C 1 = (Q 1 + Q 2 ) / P(V5)

[0179] In formula (V5), Q 1Represents the first cumulative external charging capacity of a single battery cell, with the unit of Ah, Q 2 Represents the first cumulative energy recovery capacity of a single battery cell, with the unit of Ah, P represents the rated capacity of a single battery cell, with the unit of Ah, C 1 Represents the number of charge-discharge cycles after full charge.

[0180] In some embodiments, the calculation formula for the first average ambient temperature is:

[0181] T p1 =(T 1 +T 2 ) / 2 (V6)

[0182] In formula (V6), T 1 Represents the first ambient temperature, with the unit of °C, T 2 Represents the second ambient temperature, with the unit of °C, T p1 Represents the first average ambient temperature, with the unit of °C.

[0183] In some embodiments, the calculation formula for the first true average self-discharge current is:

[0184] I x1 =I p1 ×K T1 ×(K C1 +K L1 ) / 2 (V7)

[0185] In formula (V7), I p1 Represents the first initial average self-discharge current of a single battery cell, with the unit of A, K T1 Represents the first temperature correction coefficient, K C1 Represents the first cycle number correction coefficient, K L1 Represents the first calendar life correction coefficient, I x1 Represents the first true average self-discharge current of a single battery cell, with the unit of A;

[0186] Among them, the calculation formula for K T1 is:

[0187] K T1 =P b / P a (V8)

[0188] In formula (V8), P b Represents the capacity of a single battery cell at the first average ambient temperature, with the unit of Ah, P a Represents the capacity of a single battery cell at room temperature, with the unit of Ah, K T1 Represents the first temperature correction coefficient;

[0189] Among them, the capacity of a single battery cell P at room temperaturea and the single-cell capacity P of the battery at the first average ambient temperature b is obtained by referring to the correspondence table between temperature and the single-cell capacity of the battery. The correspondence table between temperature and the single-cell capacity of the battery is obtained through experimental tests. For example, the single-cell capacity of the battery at room temperature is 100 Ah, and the single-cell capacity of the battery at 0 °C is 80 Ah. Then the temperature correction coefficient at 0 °C is 0.8. Similarly, the correction coefficients under other temperature conditions can be measured. Subsequently, the calculation of K T2 is the same;

[0190] K C1 The calculation formula is:

[0191] K C1 = 1 - (η max / C s ) × C 1 (V9)

[0192] In formula (V9), η max represents the maximum capacity attenuation rate of the battery single cell under the preset number of cycles, C s represents the preset number of cycles, C 1 represents the number of charge and discharge cycles after full charge, and K C1 represents the first cycle number correction coefficient;

[0193] Among them, the preset number of cycles of the battery single cell is the number of charge and discharge cycles determined at the time of battery factory shipment. The maximum capacity attenuation rate is determined according to the quality assurance requirements of this battery single cell. The maximum capacity attenuation rate for the industry convention of 10 years or 300,000 kilometers is 30%.

[0194] K L1 The calculation formula is:

[0195] K L1 = 1 - (η max / K s ) × L 1 (V10)

[0196] In formula (V10), η max represents the maximum capacity attenuation rate of the battery single cell under the preset number of cycles, K s represents the preset calendar life, in months, L 1 represents the first calendar life, in months, and K L1 represents the first calendar life correction coefficient.

[0197] In some embodiments, as Figure 3 shown, the method for monitoring the self-discharge of a power battery further includes the following steps:

[0198] S6. When the power battery is fully charged and discharged again to the first time, according to the methods of S1 to S4, obtain the third voltage, fourth voltage, second cumulative charge capacity, second initial average self-discharge current, charge-discharge cycle times after the second full charge, second average ambient temperature, and second true average self-discharge current of the battery single cell;

[0199] S7. According to the first cumulative charge capacity and the second cumulative charge capacity, obtain the increment of the cumulative charge capacity. According to the first true average self-discharge current and the second true average self-discharge current, obtain the increment of the true average self-discharge current;

[0200] S8. According to the increment of the cumulative charge capacity and the increment of the true average self-discharge current, obtain the change rate of the self-discharge rate;

[0201] S9. When the change rate of the self-discharge rate is greater than the preset change rate of the fault self-discharge rate, alarm for abnormal self-discharge.

[0202] By obtaining the second cumulative charge capacity and the second true average self-discharge current of the battery single cell after the power battery is fully charged and discharged again, and combining the first cumulative charge capacity and the first true average self-discharge current after the previous full charge and discharge, obtain the increment of the cumulative charge capacity and the increment of the true average self-discharge current, and then calculate the change rate of the self-discharge rate to judge the abnormal situation of the battery self-discharge, so as to dynamically reflect the change trend of the battery self-discharge behavior, thus discovering the abnormal change of the battery self-discharge behavior earlier, further improving the accuracy of the power battery self-discharge early warning, and effectively avoiding the further deterioration of the battery performance.

[0203] In some embodiments, as Figure 4 shown, in S6, it includes the following steps:

[0204] S61. When the power battery is fully charged and discharged again to the first time, obtain the third voltage, second cumulative charge capacity, and third ambient temperature of the battery single cell;

[0205] S62. When the power battery is fully charged and discharged again to the second time, obtain the fourth voltage, fourth ambient temperature, and second calendar life of the battery single cell;

[0206] S63. According to the third voltage, fourth voltage, OCV-SOC curve, rated capacity, first time, second time, second cumulative charge capacity, third ambient temperature, and fourth ambient temperature, obtain the second initial average self-discharge current, charge-discharge cycle times after the second full charge, and second average ambient temperature of the battery single cell;

[0207] S64. Correct the second initial average self-discharge current through the number of charge-discharge cycles after the second full charge, the second calendar life, the maximum capacity attenuation rate, and the cell capacity at the second average ambient temperature to obtain the second true average self-discharge current.

[0208] Exemplarily, for the power battery on a vehicle, a complete power battery assembly is usually composed of multiple battery single cells connected in series. Taking a certain battery single cell as an example, the power battery self-discharge monitoring method further includes that after the vehicle is fully charged and powered off and enters the sleep state for the (n + 1)-th (where n represents the number of full charges of the power battery, n ≥ 1) time, the following steps are also carried out:

[0209] S61. When it is recognized that the power battery of the vehicle is fully charged and powered off to the first time again (i.e., the (n + 1)-th time), wake up the power battery BMS for the first time at a low voltage. Specifically, wake up the vehicle controller 5 through the battery management system 6, obtain the third voltage, the second cumulative charge capacity, and the third ambient temperature of the battery single cell stored in the vehicle controller 5 at this time, upload the obtained data to the cloud through the vehicle-mounted remote terminal T-BOX 7 and store it in the database of the big data cloud platform 8. After the upload is completed, all the vehicle controllers are powered off and enter the sleep state;

[0210] S62. After the first data upload and entering the sleep state, the battery management system 6 starts timing again internally. When it is recognized that the power battery of the vehicle is fully charged and powered off to the second time again (i.e., the (n + 1)-th time), and the power battery has not been powered on at a high voltage during the period from the first time to the second time, wake up the power battery BMS for the second time at a low voltage. Specifically, wake up the vehicle controller 5 again through the battery management system 6, obtain the fourth voltage, the fourth ambient temperature, and the second calendar life of the battery single cell at this time, upload the obtained data to the cloud through the vehicle-mounted remote terminal T-BOX 7 and store it in the database of the big data cloud platform 8. After the upload is completed, all the vehicle controllers are powered off and enter the sleep state. To ensure the accuracy of the subsequent self-discharge rate calculation, the time t2 should be as long as possible, and the second time is at least greater than 2 times the first time;

[0211] S63. Obtain the second initial average self-discharge current, the number of charge-discharge cycles after the second full charge, and the second average ambient temperature of the battery single cell according to the third voltage, the fourth voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the second cumulative charge capacity, the third ambient temperature, and the fourth ambient temperature;

[0212] S64. Correct the second initial average self-discharge current through the number of charge-discharge cycles after the second full charge, the second calendar life, the maximum capacity attenuation rate, and the cell capacity at the second average ambient temperature to obtain the second true average self-discharge current;

[0213] S7. Obtain the increment of the cumulative charge input based on the first cumulative charge input and the second cumulative charge input, and obtain the increment of the true average self-discharge current based on the first true average self-discharge current and the second true average self-discharge current;

[0214] S8. Obtain the change rate of the self-discharge rate based on the increment of the cumulative charge input and the increment of the true average self-discharge current;

[0215] S9. When the change rate of the self-discharge rate is greater than the change rate of the preset fault self-discharge rate, alarm for abnormal self-discharge.

[0216] Exemplarily, the change rate of the preset fault self-discharge rate needs to be determined according to the actual cell material system and test results.

[0217] In some embodiments, the calculation method of the second initial average self-discharge current is as follows:

[0218] Obtain the third true remaining charge of the single cell based on the third voltage and the OCV-SOC curve, and then combine with the rated capacity to calculate the third true capacity of the single cell;

[0219] Obtain the fourth true remaining charge of the single cell based on the fourth voltage and the OCV-SOC curve, and then combine with the rated capacity to calculate the fourth true capacity of the single cell;

[0220] Obtain the second self-discharge capacity attenuation of the single cell based on the third true capacity and the fourth true capacity, and then combine with the first time and the second time to calculate the second initial average self-discharge current.

[0221] In some embodiments, the calculation method of the number of charge-discharge cycles after the second full charge is as follows:

[0222] Calculate the number of charge-discharge cycles after the second full charge according to the second cumulative charge input and the rated capacity;

[0223] The second cumulative charge input includes the second cumulative external charging capacity and the second cumulative energy recovery capacity.

[0224] In some embodiments, the calculation method of the second average ambient temperature is as follows:

[0225] Calculate the second average ambient temperature according to the third ambient temperature and the fourth ambient temperature;

[0226] In some embodiments, the calculation formula of the third true capacity of the single cell is:

[0227] P 3 =SOC 3 ×P(V11)

[0228] In formula (V11), SOC 3 represents the third true remaining charge of the battery single cell, in Ah, P represents the rated capacity of the battery single cell, in Ah, P 3 represents the third true capacity of the battery single cell, in Ah.

[0229] In some embodiments, the calculation formula for the fourth true capacity of the battery single cell is:

[0230] P 4 = SOC 4 × P(V12)

[0231] In formula (V12), SOC 4 represents the fourth true remaining charge of the battery single cell, in Ah, P represents the rated capacity of the battery single cell, in Ah, P 4 represents the fourth true capacity of the battery single cell, in Ah.

[0232] In some embodiments, the calculation formula for the second self-discharge capacity attenuation of the battery single cell is:

[0233] ΔP 2 = P 3 - P 4 (V13)

[0234] In formula (V13), P 3 represents the third true capacity of the battery single cell, in Ah, P 4 represents the fourth true capacity of the battery single cell, in Ah, ΔP 2 represents the second self-discharge capacity attenuation of the battery single cell, in Ah;

[0235] The calculation formula for the second initial average self-discharge current is:

[0236] I p2 = ΔP 2 / (t 2 - t 1 )(V14)

[0237] In formula (V14), ΔP 2 represents the second self-discharge capacity attenuation of the battery single cell, in Ah, t 1 represents the first time, in h, t 2 represents the second time, in h; I p2 represents the second initial average self-discharge current of the battery single cell, in A.

[0238] In some embodiments, the calculation formula for the number of charge-discharge cycles after re-full charge is:

[0239] C2 =(Q 3 +Q 4 ) / P(V15)

[0240] In formula (V15), Q 3 represents the second cumulative external charging capacity of a single battery cell, with the unit of Ah, Q 4 represents the second cumulative energy recovery capacity of a single battery cell, with the unit of Ah, P represents the rated capacity of a single battery cell, with the unit of Ah, C 2 represents the number of charge-discharge cycles after being fully charged again.

[0241] In some embodiments, the calculation formula for the second average ambient temperature is:

[0242] T p2 =(T 3 +T 4 ) / 2(V16)

[0243] In formula (V16), T 3 represents the third ambient temperature, with the unit of °C, T 4 represents the fourth ambient temperature, with the unit of °C, T p2 represents the second average ambient temperature, with the unit of °C.

[0244] In some embodiments, the calculation formula for the second true average self-discharge current is:

[0245] I x2 =I p2 ×K T2 ×(K C2 +K L2 ) / 2(V17)

[0246] In formula (V17), I p2 represents the second initial average self-discharge current of a single battery cell, with the unit of A, K T2 represents the second temperature correction coefficient, K C2 represents the second cycle number correction coefficient, K L2 represents the second calendar life correction coefficient, I x2 represents the second true average self-discharge current of a single battery cell, with the unit of A;

[0247] Among them, the calculation formula for K T2 is:

[0248] K T2 =P c / P a (V18)

[0249] In formula (V18), P cRepresents the single-cell capacity of the battery at the second average ambient temperature, in Ah, P a Represents the single-cell capacity of the battery at room temperature, in Ah, K T2 Represents the second temperature correction factor.

[0250] The single-cell capacity of the battery at room temperature P a And the single-cell capacity of the battery at the second average ambient temperature P c Are obtained by referring to the corresponding relationship table between temperature and single-cell capacity of the battery. The corresponding relationship table between temperature and single-cell capacity of the battery is obtained through experimental tests.

[0251] K C2 The calculation formula for is:

[0252] K C2 = 1 - (η max / C s ) × C 2 (V19)

[0253] In formula (V19), η max Represents the maximum capacity decay rate of the battery single cell under the preset number of cycles, C s Represents the preset number of cycles, C 2 Represents the number of charge-discharge cycles after a full charge again, K C2 Represents the second cycle number correction factor.

[0254] For example, when the preset number of cycles C of the battery single cell s Is 3000 times and the maximum capacity decay rate η max Is 30%, K C2 = 1 - (0.3 / 3000) × C 2 .

[0255] K L2 The calculation formula for is:

[0256] K L2 = 1 - (η max / K s ) × L 2 (V20)

[0257] In formula (V20), η max Represents the maximum capacity decay rate of the battery single cell under the preset number of cycles, K s Represents the preset calendar life, L 2 Represents the second calendar life, K L2 Represents the second calendar life correction factor.

[0258] For example, when the preset calendar life K of the battery single cell s Is 360 months and the maximum capacity decay rate η maxWhen it is 30%, K L2 = 1 - (0.3 / 360) × C 2 .

[0259] In some embodiments, the calculation formula for the increment of the cumulative charging capacity is:

[0260] ΔQ = (Q 3 + Q 4 ) - (Q 1 + Q 2 )(V21)

[0261] In formula (V21), Q 3 represents the second cumulative external charging capacity of a single battery cell, in Ah, Q 4 represents the second cumulative energy recovery capacity of a single battery cell, in Ah, Q 1 represents the first cumulative external charging capacity of a single battery cell, in Ah, Q 2 represents the first cumulative energy recovery capacity of a single battery cell, in Ah, and ΔQ represents the increment of the cumulative charging capacity of a single battery cell, in Ah.

[0262] In some embodiments, the calculation formula for the increment of the true average self-discharge current is:

[0263] ΔI = I x2 - I x1 (V22)

[0264] In formula (V22), I x2 represents the second true average self-discharge current of a single battery cell, in A, I x1 represents the first true average self-discharge current of a single battery cell, in A, and ΔI represents the increment of the true average self-discharge current of a single battery cell, in A.

[0265] In some embodiments, the calculation formula for the change rate of the self-discharge rate is:

[0266] Δσ = ΔI / ΔQ (V23)

[0267] In formula (V23), ΔI represents the increment of the true average self-discharge current of a single battery cell, in Ah, ΔQ represents the increment of the cumulative charging capacity of a single battery cell, in Ah, and Δσ represents the change rate of the self-discharge rate of a single battery cell, in h -1 .

[0268] In some embodiments, as Figure 5 shown, there is also provided a system for implementing the power battery self-discharge monitoring method in any of the above embodiments, including:

[0269] The data acquisition module 1 is configured to obtain the first voltage, the first cumulative charge capacity, the first ambient temperature, and the first calendar life of the battery single cell when the power battery is fully charged and discharged to the first time; and is configured to obtain the second voltage and the second ambient temperature of the battery single cell when the power battery is fully charged and discharged to the second time, where the second time is greater than twice the first time.

[0270] The self-discharge current calculation module 2 is configured to obtain the first initial average self-discharge current, the number of charge-discharge cycles after full charge, and the first average ambient temperature of the battery single cell according to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charge capacity, the first ambient temperature, and the second ambient temperature.

[0271] The self-discharge current correction module 3 is configured to correct the first initial average self-discharge current through the number of charge-discharge cycles after full charge, the first calendar life, the maximum capacity attenuation rate, and the cell capacity at the first average ambient temperature to obtain the first true average self-discharge current.

[0272] The abnormal alarm module 4 is configured to alarm abnormal self-discharge when the first true average self-discharge current is greater than the preset fault self-discharge current threshold.

[0273] In some embodiments, as Figure 6 shown, there is also provided an electronic device, including a memory 9 and a processor 10. The memory 9 stores a computer program, and when the processor 10 executes the computer program, the steps of the power battery self-discharge monitoring method in any of the above embodiments are implemented.

[0274] In some embodiments, there is also provided a vehicle including any of the above electronic devices.

[0275] In summary, the power battery self-discharge monitoring method of the present invention obtains multi-dimensional data such as the voltage, cumulative charge capacity, ambient temperature, and calendar life of the battery single cell at different time points, and uses the OCV-SOC curve to determine the true state of charge (SOC) of the battery, avoiding the error caused by simply relying on voltage or capacity to calculate the initial average self-discharge current. Further, by combining factors such as the number of charge-discharge cycles of the power battery, the calendar life, the maximum capacity attenuation rate, and the cell capacity at the average ambient temperature, the initial average self-discharge current is corrected to obtain a more real average self-discharge current, improving the accuracy of early warning. Thus, the problem of low accuracy existing in the existing power battery self-discharge early warning method is effectively solved.

[0276] The method for monitoring the self-discharge of power batteries of the present invention not only considers the voltage change of a single battery cell but also combines multiple factors such as the cumulative charge capacity, ambient temperature, and calendar life to achieve a comprehensive monitoring of the self-discharge of power batteries. This helps to promptly detect changes in battery performance and prevent potential safety hazards. When the calculated true average self-discharge current exceeds the preset fault self-discharge current threshold, the method can immediately issue an alarm signal to indicate abnormal self-discharge. This helps to promptly detect and handle the self-discharge problem of power batteries, avoid further deterioration of battery performance, and ensure the safe operation of the battery system. It has the value of popularization and application in the field of vehicle battery safety technology.

[0277] The above embodiments are only used to exemplarily illustrate the principle and its effects of the present invention, rather than to limit this application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for monitoring self-discharge of a power battery, characterized in that: The following steps are involved: S1. When the power battery is fully charged and powered off for a first time, obtaining a first voltage, a first accumulated charging capacity, and a first ambient temperature of a battery cell; S2. when the power battery is fully charged and powered off for a second time, obtaining a second voltage, a second ambient temperature, and a first calendar life of the battery cell, wherein the second time is greater than twice the first time; S3, obtaining a first initial average self-discharge current of the battery cell, a number of charge and discharge cycles after full charge, and a first average ambient temperature according to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charging capacity, the first ambient temperature, and the second ambient temperature; S4, correcting the first initial average self-discharge current according to the number of charge and discharge cycles after full charge, the first calendar life, the maximum capacity decay rate and the cell capacity at the first average ambient temperature to obtain a first real average self-discharge current; S5. When the first real average self-discharge current is greater than the preset fault self-discharge current threshold, an alarm is issued for self-discharge abnormality.

2. The power battery self-discharge monitoring method according to claim 1, characterized in that: The first initial average self-discharge current is calculated as: Obtaining a first real remaining power of the battery cell according to the first voltage and the OCV-SOC curve, and then calculating a first real capacity of the battery cell in combination with the rated capacity; According to the second voltage and the OCV-SOC curve, a second real remaining power of the battery cell is obtained, and then combined with the rated capacity, a second real capacity of the battery cell is calculated; The first self-discharge capacity decay of the battery cell is obtained according to the first real capacity and the second real capacity, and then the first initial average self-discharge current is calculated by combining the first time and the second time.

3. The power battery self-discharge monitoring method according to claim 1, characterized in that: The calculation method of the number of charge and discharge cycles after full charge is: Calculating the number of charge-discharge cycles after full charge according to the first accumulated charge capacity and the rated capacity; The first accumulated charging capacity includes a first accumulated external charging capacity and a first accumulated energy recovery capacity.

4. The power battery self-discharge monitoring method according to claim 1, characterized in that: The first average ambient temperature is calculated as follows: The first average ambient temperature is calculated according to the first ambient temperature and the second ambient temperature.

5. The power battery self-discharge monitoring method according to claim 1, characterized in that: The following steps are also included: When the power battery is fully charged again and powered off to the first time, according to the methods of S1 to S4, a third voltage, a fourth voltage, a second cumulative charged capacity, a second initial average self-discharge current, a number of charge and discharge cycles after full charging again, a second average ambient temperature, and a second real average self-discharge current of the battery cell are obtained; Obtaining an increment of the cumulative charging capacity according to the first cumulative charging capacity and the second cumulative charging capacity, and obtaining an increment of the real average self-discharge current according to the first real average self-discharge current and the second real average self-discharge current; According to the increment of the cumulative charged capacity and the increment of the real average self-discharge current, the change rate of the self-discharge rate is obtained; When the change rate of the self-discharge rate is greater than the change rate of the preset fault self-discharge rate, an alarm is issued for self-discharge abnormality.

6. The method for monitoring self-discharge of a power battery according to claim 5, characterized in that: The second initial average self-discharge current is calculated as: According to the third voltage and the OCV-SOC curve, a third real remaining power of the battery cell is obtained, and then combined with the rated capacity, a third real capacity of the battery cell is calculated; According to the fourth voltage and the OCV-SOC curve, a fourth real remaining power of the battery cell is obtained, and then combined with the rated capacity, a fourth real capacity of the battery cell is calculated; The second self-discharge capacity decay of the battery cell is obtained according to the third real capacity and the fourth real capacity, and then the second initial average self-discharge current is calculated by combining the first time and the second time.

7. The power battery self-discharge monitoring method according to claim 5, characterized in that: The calculation method of the number of charge and discharge cycles after full charging again is: Calculating the number of charge-discharge cycles after full charging again according to the second accumulated charge capacity and the rated capacity; The second accumulated charging capacity includes a second accumulated external charging capacity and a second accumulated energy recovery capacity.

8. A system for implementing the power battery self-discharge monitoring method according to any one of claims 1 to 7, characterized in that: include: A data acquisition module (1) is used to acquire a first voltage, a first accumulated charging capacity and a first ambient temperature of a battery cell when the power battery is fully charged and powered off for a first time; and for obtaining a second voltage, a second ambient temperature, and a first calendar life of a battery cell when the power battery is fully charged and powered off for a second time, wherein the second time is greater than twice the first time; A self-discharge current calculation module (2) is used to obtain a first initial average self-discharge current of the battery cell, a number of charge and discharge cycles after full charge, and a first average ambient temperature according to the first voltage, the second voltage, the OCV-SOC curve, the rated capacity, the first time, the second time, the first cumulative charged capacity, the first ambient temperature, and the second ambient temperature; A self-discharge current correction module (3) is used to correct a first initial average self-discharge current according to the number of charge and discharge cycles after full charge, the first calendar life, the maximum capacity decay rate and the cell capacity at a first average ambient temperature, so as to obtain a first real average self-discharge current; The abnormality alarm module (4) is used to alarm a self-discharge abnormality when the first real average self-discharge current is greater than a preset fault self-discharge current threshold.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the power battery self-discharge monitoring method according to any one of claims 1 to 7 are implemented.

10. A vehicle, characterized in that: The vehicle includes the electronic device according to claim 9.

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