Battery charging control method and device, electronic equipment and storage medium

Abstract

The invention discloses a battery charging control method and device, electronic equipment and a storage medium, and relates to the technical field of battery charging control. According to the technical scheme, when it is judged that the verification task needs to be executed, the battery impedance of the target battery in the charging process is obtained, and the verification task is a task for verifying that the target battery does not have safety risks due to the lithium precipitation phenomenon during charging; obtaining an impedance change rate curve of the target battery according to all the battery impedances, wherein the impedance change rate curve is a curve of the impedance change rate of the target battery along with the change of the residual electric quantity; according to the impedance change rate curve, the maximum charging amount of safe charging of the target battery is determined, and based on the maximum charging amount, safety risks caused by lithium precipitation during charging of the target battery can be avoided, so that when a charging terminal of the target battery is controlled based on the maximum charging amount to execute a charging task, the charging efficiency is improved. The safety risk influence of the lithium precipitation phenomenon on battery charging can be effectively reduced, and the safety in the battery charging process is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging control, and in particular to a battery charging control method, device, electronic equipment and storage medium. Background Art

[0002] The large-scale promotion and application of new energy vehicles has put forward new requirements for the performance stability of batteries in various complex working environments. The fast charging capability of lithium-ion batteries provides a promising solution to the range anxiety of electric vehicles. For example, the rapidly developing ternary cathode batteries are expected to achieve low-temperature fast charging performance that meets customer needs. The advantages of ternary cathode materials are high energy density, good cycle performance, and excellent fast charge and discharge performance. However, excessive charging rates, especially high charging rates in low temperature environments, can cause very serious voltage polarization, resulting in uneven and unstable lithium plating behavior, causing serious safety problems. Summary of the invention

[0003] In order to solve the technical problem of how to reduce the impact of lithium plating on the safety of battery charging, the present invention provides a battery charging control method, device, electronic device and storage medium, which can effectively reduce the safety risk impact of lithium plating on battery charging and improve the safety of the battery charging process.

[0004] The embodiment of the present invention provides the following solution:

[0005] In a first aspect, an embodiment of the present invention provides a battery charging control method, the method comprising:

[0006] Determine whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is to verify that the target battery does not present a safety risk due to lithium deposition during charging;

[0007] When a calibration task needs to be performed, the battery impedance of the target battery during the charging process is obtained;

[0008] Obtaining an impedance change rate curve of a target battery according to the impedances of all the batteries, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power;

[0009] Determine the maximum charge amount of the target battery for safe charging according to the impedance change rate curve;

[0010] The charging terminal of the target battery is controlled to perform the charging task according to the maximum charging amount.

[0011] In an optional embodiment, determining whether it is necessary to perform a safe charging verification task on a target battery includes:

[0012] Obtaining target data of a target battery, wherein the target data is data related to the usage time, charging environment temperature, or charge and discharge times of the target battery;

[0013] When the target data is not within the preset safety interval, it is determined that a verification task needs to be performed.

[0014] In an optional embodiment, obtaining the battery impedance of the target battery during the charging process includes:

[0015] When the current remaining power of the target battery is lower than a preset first power threshold, intermittently charging the target battery according to a preset charging rate curve, wherein the charging rate curve is a curve showing a change in charging rate with the remaining power;

[0016] According to the data collected during the intermittent charging of the target battery, a charging current and a first charging voltage and a second charging voltage before and after the rest period are obtained;

[0017] The battery impedance of the target battery at the corresponding charging rate is obtained according to the charging current, the first charging voltage and the second charging voltage.

[0018] In an optional embodiment, intermittently charging the target battery according to a preset charging rate curve includes:

[0019] When the charging environment temperature of the target battery is greater than a preset temperature threshold, the target battery is intermittently charged at room temperature according to the charging parameters represented by the charging rate curve until the remaining power of the target battery reaches a first target power when the battery is fully charged;

[0020] When the charging environment temperature is less than or equal to the temperature threshold, the target battery is intermittently charged at low temperature according to the charging parameters represented by the charging rate curve, and is charged with a charging current lower than the current threshold after charging is cut off until the remaining power of the target battery reaches the second target power when the battery is fully charged.

[0021] In an optional embodiment, before performing low-temperature intermittent charging on the target battery according to the charging parameters represented by the charging rate curve, the method further includes:

[0022] Obtain the corresponding relationship between different charging currents and charging amounts during low-temperature intermittent charging;

[0023] Determine the charging current that is greater than the preset second power threshold in the corresponding relationship as the adaptation current that meets the low-temperature charging condition;

[0024] Determine whether the target battery will experience a secondary impedance reduction when low-temperature intermittent charging is performed using all adapted currents;

[0025] If not, the corresponding adaptation current is determined as the target current for implementing low-temperature intermittent charging.

[0026] In an optional embodiment, the impedance change rate curve includes a first change rate curve corresponding to when the charging environment temperature is greater than a temperature threshold, and a second change rate curve corresponding to when the charging environment temperature is less than or equal to the temperature threshold; determining the maximum charge amount of the target battery for safe charging according to the impedance change rate curve includes:

[0027] Extracting the minimum change rate of the battery impedance from the data represented by the first change rate curve, and determining the minimum change rate as a change rate threshold for safe charging;

[0028] Determine the remaining power corresponding to the change rate threshold in the second change rate curve as the safe charging capacity;

[0029] A safe charging capacity that is greater than a preset third power threshold is determined as a maximum charging capacity.

[0030] In an optional embodiment, after determining the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve, the method further includes:

[0031] Obtaining the maximum charge capacity of the target battery under the target conditions for the first time, wherein the target conditions are charging conditions when the charging environment temperature is lower than the temperature threshold and the charging rate is higher than the rate threshold;

[0032] Determine the maximum number of charge and discharge times of the target battery under the target conditions according to the maximum charge capacity under the target conditions;

[0033] When the target battery is charged under the target condition, the charging times of the target battery are recorded and an alarm is issued according to the maximum charging and discharging times.

[0034] In a second aspect, an embodiment of the present invention further provides a battery charging control device, the device comprising:

[0035] A judgment module, used to judge whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is a task of verifying that the target battery does not present a safety risk due to lithium deposition during charging;

[0036] A first acquisition module, used to acquire the battery impedance of the target battery during the charging process when a calibration task needs to be performed;

[0037] An acquisition module, used for acquiring an impedance change rate curve of a target battery according to all battery impedances, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power;

[0038] A first determination module is used to determine the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve;

[0039] The control module is used to control the charging terminal of the target battery to perform the charging task according to the maximum charging amount.

[0040] In a third aspect, an embodiment of the present invention further provides an electronic device, comprising a processor and a memory, wherein the memory is coupled to the processor and stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of any one of the methods in the first aspect.

[0041] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods in the first aspect.

[0042] Compared with the prior art, the battery charging control method, device, electronic device and storage medium of the present invention have the following advantages:

[0043] The technical solution of the present invention obtains the battery impedance of the target battery during the charging process when it is determined that a verification task needs to be performed. The verification task is to verify that the target battery does not have a safety risk due to lithium plating during charging; an impedance change rate curve of the target battery is obtained based on all battery impedances. Since the impedance change rate curve is a curve of the impedance change rate of the target battery as a inverse of the remaining power, the maximum charging amount of the target battery for safe charging can be further determined based on the impedance change rate curve. Based on the maximum charging amount, the target battery can be charged without a safety risk due to lithium plating. When a charging terminal that controls the target battery based on the maximum charging amount performs a charging task, the safety risk impact of lithium plating on battery charging can be effectively reduced, thereby improving the safety of the battery during charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flowchart of a battery charging control method provided by an embodiment of the present invention;

[0046] Figure 2-1 Current curve of normal intermittent charging provided by the embodiment of the present invention Figure 1 ;

[0047] Figure 2-2 The voltage curve of normal intermittent charging provided by the embodiment of the present invention Figure 1 ;

[0048] Figure 3-1 A second current curve diagram of low temperature intermittent charging provided by an embodiment of the present invention;

[0049] Figure 3-2 A voltage curve diagram 2 of low temperature intermittent charging provided by an embodiment of the present invention;

[0050] Figure 4 An impedance curve diagram of intermittent charging provided by an embodiment of the present invention;

[0051] Figure 5 Schematic diagram of the impedance change rate curve provided by the embodiment of the present invention Figure 1 ;

[0052] Figure 6 Schematic diagram 2 of an impedance change rate curve provided by an embodiment of the present invention;

[0053] Figure 7 An overall implementation flow chart of the battery charging control method provided by an embodiment of the present invention;

[0054] Figure 8 A schematic diagram of the structure of a battery charging control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the embodiments of the present invention.

[0056] The control method proposed in the embodiment of the present invention can be applied to the charging control of any battery, and the following will be specifically described by taking the power battery of the vehicle as an example. For power batteries, there are currently many schemes for studying the performance changes of the battery after low-temperature charging and the lithium precipitation phenomenon through non-in-situ methods. Usually, after the battery experiences extreme working conditions, the graphite negative electrode is disassembled and the microstructure is observed, and the composition is determined by other methods to establish a quantitative relationship between the battery life change, lithium precipitation behavior, electrolyte composition, and charging conditions. The non-in-situ method has the characteristics of accuracy but hysteresis, and is mainly used in laboratory research. It has some reference value for the potential hidden dangers of power batteries, but does not have real-time judgment and early warning capabilities. Power batteries pay more attention to in-situ detection during low-temperature charging. Especially when applied to low-temperature environments (for example, less than minus 20°C), its high energy density advantage will be significantly affected, and fast charging can only reach less than 70% of the capacity of room temperature. Lithium precipitation is more likely to occur in low-temperature environments, and it is difficult to implement effective detection, resulting in insufficient safety of power battery charging. The following will take the power battery of the vehicle as an example to specifically describe the proposed technical solution.

[0057] See also Figure 1 , Figure 1 The flowchart of a battery charging control method provided in an embodiment of the present invention can be applied to a battery control terminal to implement battery charging control. The control terminal can be a battery charging controller or a vehicle battery management system (BMS) that can run the control method, and no specific restrictions are made here. The control method includes:

[0058] S11. Determine whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is a task of verifying that the target battery does not present a safety risk due to lithium deposition during charging.

[0059] Specifically, the target battery can be a vehicle's power battery, or a battery installed in other devices or terminals. The verification task can be executed at any time during the use of the target battery; it can also be determined whether to execute based on a preset flag, such as using the usage time as a flag to determine whether to execute the verification task. As the usage time of the target battery increases, the probability of lithium plating will increase accordingly. When the single continuous use time of the target battery reaches the preset time, it is determined that the verification task needs to be executed.

[0060] Exemplarily, step S11 includes sub-steps S11-1 to S11-2, which are specifically described as follows:

[0061] S11-1, obtaining target data of the target battery. The target data is data related to the occurrence of lithium deposition in the target battery, which can be data on the use time of the target battery, the charging environment temperature, or the number of charge and discharge times, or the mileage of the vehicle, as long as it is related to the lithium deposition phenomenon. The target data can be obtained through a sensor or through software timer measurement, and no specific limitation is made here.

[0062] S11-2. When the target data is not in the preset safety interval, it is determined that a verification task needs to be performed. The safety interval can be set based on the experience of the technician or determined through a calibration experiment. When the target data is in the safety interval, it means that the probability of lithium deposition in the target battery is small, and there is no need to perform a verification task, and monitoring continues; conversely, when the target data is not in the safety interval, it means that the probability of lithium deposition in the target battery is high, and it is determined that a verification task needs to be performed, and the process proceeds to step S12.

[0063] S12. When a calibration task needs to be performed, the battery impedance of the target battery during the charging process is obtained.

[0064] Specifically, battery impedance is the ratio of charging voltage to charging current, and battery impedance can be measured at different frequencies. Changes in battery impedance can reveal the chemical reactions inside the battery, interface characteristics, the state of electrode materials, and lithium precipitation characteristics. It can be understood that when obtaining battery impedance, the charging voltage and charging current can be directly collected and calculated, or a small AC signal can be applied and the response can be measured to achieve it.

[0065] In practical applications, if the remaining power of the target battery is large, it may be impossible to obtain a complete and accurate battery impedance. Based on this, in a specific implementation, step S12 includes sub-steps S12-1 to S12-3, which are specifically described as follows:

[0066] S12-1. When the current remaining power of the target battery is lower than the preset first power threshold, it means that the remaining power of the target battery is small and a complete charging process can be implemented. Then, the target battery is intermittently charged according to the preset charging rate curve. The charging rate curve is a curve in which the charging rate changes with the remaining power. It can be set based on the actual situation of the target battery. For example, when the remaining power is small, a larger rate is used for charging; as the charging task continues, the remaining power gradually increases, and a smaller rate is used for charging. Intermittent charging is to stop charging for a preset period of time after charging a preset power or a preset time, and then continue charging until the target battery is fully charged.

[0067] See also Figure 2-1 and Figure 2-2During intermittent charging at room temperature, a given time △t is placed on hold every time a fixed percentage of the total charge, such as 1% or less, is charged, where △t is the difference between time t2 and time t1.

[0068] S12-2, according to the data collected by the target battery during intermittent charging, obtain the charging current and the first charging voltage and the second charging voltage before and after the rest period. In the intermittent charging process, the rest period is the time period when charging is stopped, and the charging current value I1 before the suspension (time t1), the voltage value U1 before the suspension (time t1), and the voltage value U2 after the suspension (time t2) are recorded, where I1 is the charging current, U1 is the first charging voltage, and U2 is the second charging voltage.

[0069] S12-3. Obtain the battery impedance of the target battery at the corresponding charging rate according to the charging current, the first charging voltage and the second charging voltage. The battery impedance can be calculated by Ohm's law. Based on the formula R=(U1-U2) / I1, the battery impedance (or DC impedance value) of the target battery at the corresponding remaining power (or SOC state) is calculated. It can be understood that by analyzing the SOC node (i.e., the secondary reduction state) where the battery impedance of the battery decreases, then increases, and then decreases, it is possible to determine the remaining power of the target battery at different charging rates and ambient temperatures for lithium deposition.

[0070] For the acquisition of battery impedance, the intuitive and accurate in-situ detection of the battery is the voltage relaxation method, that is, after the battery is charged, the OCV (Open Circuit Voltage) of the battery is detected by leaving it for a certain period of time, and the DC impedance (DCR) of the battery is calculated. The intermittent charging method is a detection method that has received special attention in the voltage relaxation method. The advantages of this method are simple operation and short detection time. However, this method has limitations in its application under extreme conditions such as high-rate charging or low-temperature fast charging. Especially at the moment when battery materials are developed, obvious lithium precipitation is only shown at higher residual power (for example, greater than 70% SOC); and during high-rate charging and low-temperature fast charging (below -20°C), the battery cannot be directly charged to a higher residual power, so the battery impedance spectrum obtained by the intermittent charging method is incomplete, especially the lack of key residual power data, and cannot accurately reflect the process of lithium precipitation in the battery. Based on this, in a specific embodiment, sub-step S12-1 includes:

[0071] In the first step, when the charging environment temperature of the target battery is greater than the preset temperature threshold, it means that the target battery needs to be charged at normal temperature. Then, the target battery is charged intermittently at normal temperature according to the charging parameters represented by the charging rate curve until the remaining power of the target battery reaches the first target power when the battery is fully charged. The normal temperature range is 20-25℃. When the charging environment temperature is greater than 20℃, normal temperature intermittent charging is implemented and stopped after the target battery is fully charged. During the charging process, data such as charging current and charging voltage are obtained.

[0072] In the second step, when the charging environment temperature is less than or equal to the temperature threshold, it means that the charging environment temperature is low. The target battery is charged intermittently at low temperature according to the charging parameters represented by the charging rate curve, and charged at a charging current lower than the current threshold after charging is cut off until the remaining power of the target battery reaches the second target power when the battery is fully charged. The charging current below the current threshold can be regarded as a micro current, which is set to 0.1-0.33C. For example, the charging rate for low-temperature intermittent charging at a temperature above 0°C is 0.33C, and the charging rate for low-temperature intermittent charging at 0°C and below is 0.1C.

[0073] See also Figure 3-1 and Figure 3-2 , respectively, are the current curve and voltage curve of low temperature intermittent charging. In a low temperature environment, it is impossible to directly charge the battery to a higher residual power. In the embodiment of the present invention, the residual power of the target battery is replenished to the second target power through a micro current I0, and a pulse current with a pulse length of 5s and an amplitude equal to the charging current I1 in the above-mentioned normal temperature charging scheme is used to measure the battery impedance of the target battery, and the battery impedance R = (U4-U3) / I1.

[0074] Since the charging current of micro-current charging in a low temperature environment directly affects the remaining power after charging, the accuracy of the charging current determined based on experience may be insufficient. Based on this, in a specific implementation, before performing low-temperature intermittent charging on the target battery according to the charging parameters represented by the charging rate curve, the method also includes:

[0075] The first step is to obtain the corresponding relationship between different charging currents and charging amounts during low-temperature intermittent charging. Different charging currents and corresponding charging amounts can be obtained through calibration experiments, and the corresponding relationship can be obtained based on the mapping relationship between the two; of course, the corresponding relationship between the two can also be obtained through simulation experiments.

[0076] In the second step, the charging current greater than the preset second power threshold in the corresponding relationship is determined as the adaptation current that meets the low temperature charging condition. The second power threshold can be set based on actual needs, such as 80% of the maximum SOC. The charging current greater than the preset second power threshold in the corresponding relationship can charge the target battery to a near saturated state, and it is determined as the adaptation current.

[0077] The third step is to determine whether the target battery will experience a secondary impedance reduction when all the adapted currents are used for low-temperature intermittent charging. Figure 4 , Figure 4 The impedance curve is shown in Figure 1. Curve L2 is the impedance curve after intermittent charging to saturation; curve L1 is the impedance curve after intermittent charging and then continued to be charged with a micro-current. The battery impedance drops again at the P segment of curve L1. This change is called the secondary impedance reduction phenomenon. The reason for this phenomenon is that the target battery continues to be charged in a low temperature environment and produces lithium deposition, which causes a secondary reduction in battery impedance. Figure 4 It can be seen from the curve L1 in that after continued charging with a micro-current, the impedance of the target battery drops significantly after 65% SOC, which clearly proves that the lithium deposition node of the target battery is around 65% SOC.

[0078] The fourth step, if not, is to determine the corresponding adaptation current as the target current for low-temperature intermittent charging. When the adaptation current is used to implement low-temperature intermittent charging, if the impedance of the target battery decreases again, it means that the target battery has obvious lithium deposition, and the corresponding adaptation current cannot be used to continue charging after intermittent charging; on the contrary, the corresponding adaptation current can continue to charge without lithium deposition, and the target battery can be charged to a higher residual power. Charging under this adaptation current can obtain a more complete impedance curve, and the resulting battery impedance is more comprehensive and accurate.

[0079] So far, the battery impedance of the target battery during the charging process has been obtained based on the execution of the verification task.

[0080] S13. Obtain an impedance change rate curve of the target battery according to the impedances of all the batteries, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power.

[0081] Specifically, the impedance change rate characterizes the change amplitude of the battery impedance when the remaining power of the target battery changes. For example, when the remaining power of the target battery changes by 1%, the change value of the battery impedance is obtained in mΩ, and the impedance change rate curve is obtained based on all the obtained change values. The impedance change curve obtained by the above method can be derived to obtain the impedance change rate curve of the target battery. Please refer to Figure 5 , Figure 5It is a schematic diagram of the impedance change rate curve, where the horizontal axis is the remaining power SOC, and the vertical axis is the impedance change rate Z. Curve L4 (dashed line) in the figure is the impedance change rate curve when charging at room temperature. The impedance change rate at a charging rate of 0.33C at room temperature gradually increases with the increase of the remaining power, indicating that the impedance of the target battery first decreases and then increases, and no significant impedance reduction due to lithium precipitation occurs. Curve L3 (solid line) is the impedance change rate curve when charging at a low temperature of -20℃. After obtaining the impedance change rate curve, step S14 is entered.

[0082] S14. Determine the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve.

[0083] Specifically, the impedance change rate characterizes the change amplitude of the battery impedance as the remaining power of the target battery changes during the charging process. Based on this, it can be concluded whether the target battery has lithium deposition, and the remaining power of the target battery corresponding to the critical point of lithium deposition is determined as the maximum charge amount for safe charging of the target battery. When the remaining power of the target battery is within the maximum charge amount, lithium deposition will not occur, so the target battery has higher safety during the charging process. A data processing model can be constructed based on actual application needs, and the data represented by the impedance change rate curve is input into the data processing model. The critical point of lithium deposition is identified by the data processing model, and the corresponding maximum charge amount is obtained. The data processing model can be obtained based on training and verification, which will not be described in detail here.

[0084] In practical applications, the lithium deposition of the battery is more likely to occur in a low-temperature charging environment. If the maximum charge capacity is obtained based only on the battery impedance in a normal temperature environment, there may be a problem of insufficient accuracy. Based on this, in a specific implementation, the impedance change rate curve includes a first change rate curve corresponding to when the charging environment temperature is greater than the temperature threshold, and a second change rate curve corresponding to when the charging environment temperature is less than or equal to the temperature threshold. Step S14 includes sub-steps S14-1 to S14-3, which are specifically described as follows:

[0085] S14-1. Extract the minimum change rate of the battery impedance from the data represented by the first change rate curve, and determine the minimum change rate as the change rate threshold for safe charging. The minimum value can be calculated based on the data represented by the first change rate curve to determine the minimum change rate. Use it as the boundary of safe charging of the target battery. Please continue to refer to Figure 5 , defines the minimum impedance change rate when the battery is charged at room temperature and 0.33C as the battery safety boundary reference value Z min , which is the change rate threshold.

[0086] S14-2, determining the remaining power corresponding to the change rate threshold in the second change rate curve as the safe charging capacity. Figure 5 Medium change rate threshold Z minThere are two intersection points with the impedance change rate curve L3 during low-temperature charging, and the remaining power corresponding to the two intersection points is determined as the safe charging amount.

[0087] S14-3, determine the safe charging capacity greater than the preset third power threshold as the maximum charging capacity. Figure 5 , change rate threshold Z min The remaining power corresponding to the first intersection point with the impedance change rate curve L3 is between 10% and 20%. The target battery has less remaining power in this power range, so it cannot be determined as the maximum charge capacity. The remaining power corresponding to the second intersection point is between 70% and 80%, and the remaining power corresponding to it is determined as the maximum charge capacity.

[0088] At this point, the verification task has been completed and the maximum charge capacity of the target battery for safe charging has been determined.

[0089] S15. Control the charging terminal of the target battery to perform a charging task according to the maximum charging capacity.

[0090] Specifically, in order to ensure the safety of charging the target battery, the maximum charging capacity can be used as the charging upper limit of the target battery to execute the charging task. Since the maximum charging capacity is determined by verifying that the target battery does not present a safety risk due to lithium plating during charging, the safety of the target battery may be effectively reduced due to lithium plating during the charging process.

[0091] Please continue reading Figure 5 , the battery is charged at low temperature and high rate, and the impedance change rate of the target battery is rapidly reduced to Z at the high SOC stage. min When the target battery impedance change rate reaches Z, the lithium deposition degree of the target battery will be further deepened, accompanied by a large amount of irreversible lithium deposition, which will damage the safety performance and cycle life of the battery. min The SOC state of the remaining power at the time of charging is defined as the limit SOC state of the battery under low temperature charging, which can reduce the safety of charging the target battery in a low temperature environment; at the same time, the impedance change rate of the target battery when charging at low temperature on the electric vehicle shall not be lower than Z min .

[0092] In practical applications, charging in a low temperature environment is more likely to cause lithium deposition and safety accidents. Based on this, in a specific implementation, after determining the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve, the method further includes:

[0093] S16, obtaining the maximum charge capacity of the target battery under the target conditions for the first time. The target condition is the charging condition when the charging environment temperature is lower than the temperature threshold and the charging rate is higher than the rate threshold. The target condition is the target battery being charged at a high rate under a low temperature environment. Under this condition, lithium deposition is more likely to occur, resulting in damage to the target battery or even a charging safety accident. The maximum charge capacity can be obtained based on the above method, which will not be further elaborated here.

[0094] S17. Determine the maximum number of charge and discharge times of the target battery under the target conditions based on the maximum charge capacity under the target conditions. Referring to the basic performance requirements of the target battery, the capacity attenuation during the cyclic charge and discharge process should be less than 20%. The following planning can be performed: Take the limit SOC state of the target battery for the initial low-temperature high-rate charging as S0. When the target battery undergoes multiple low-temperature high-rate charging, resulting in the limit SOC state of the battery being reduced to below 80% S0, the battery is considered to no longer meet the performance requirements. The limit SOC state of the target battery for the initial low-temperature charging is S0 = 73%. After the 40th low-temperature charging, the limit SOC is reduced to 58% (<80% S0). Therefore, the low-temperature high-rate charging life of this battery is approximately 40 cycles. Please refer to Figure 6 , Figure 6 The figure is a schematic diagram of the impedance change rate curve after low-temperature high-rate charging. Curve L5 in the figure is the impedance change rate curve of the target battery at the first charge at low temperature and high rate; curve L6 is the impedance change rate curve of the target battery at the 40th charge at low temperature and high rate. Therefore, the maximum charge and discharge times under the target conditions can be determined by the maximum charge amount and the capacity attenuation threshold set under the target conditions.

[0095] S18. When the target battery is charged under the target conditions, the charging times of the target battery are recorded and an alarm is given according to the maximum charging and discharging times. Since the maximum charging and discharging times are the upper limit of the charging times of the target battery under the target conditions, conditional judgment can be implemented based on the set value of the target conditions, and the recording is performed after one charging is completed under the target conditions until the total charging times are close to or reach the maximum charging and discharging times, and then an alarm is given to the user of the target battery to remind the user to perform battery maintenance or replacement. This implementation strategy can effectively reduce the safety risk of batteries when charging at low temperatures and high rates.

[0096] The following embodiments of the present invention will generally describe the proposed technical solution. Figure 7 , Figure 7 This is a flowchart for the overall implementation of the battery charging control method. Specifically, it includes:

[0097] S71. In a low temperature environment, the battery is intermittently charged with a preset charging current I1. After each fixed charging interval, the battery immediately enters a rest phase of a given time △t, records the voltage values ​​before and after the rest, and starts charging again.

[0098] S72, when the battery is charged to the cut-off voltage with the preset charging current I1 in a low temperature environment, the intermittent charging is terminated and the battery is charged with a micro current.

[0099] S73. After charging to the target SOC state with I0, apply a DC pulse current with an amplitude of I1 and a given duration, record the voltage values ​​before and after the pulse, leave it for △t, repeat the operation until it is charged to 100% SOC, or the battery reaches the cut-off voltage during micro-current charging, and stop the test.

[0100] S74. Calculate the impedance value of the battery at each SOC state by Ohm's law, draw an impedance change rate map, and determine the battery's lithium plating starting node and low-temperature high-rate charging safety boundary Z min .

[0101] S75. Record the limit SOC state S0 of the battery after the initial low-temperature charging test, compare the attenuation of the limit SOC during the long-term test, and estimate the change in battery life.

[0102] Based on the same technical concept as the control method, the embodiment of the present invention also provides a battery charging control device, see Figure 8 , Figure 8 The control device includes:

[0103] The judgment module 801 is used to judge whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is a task of verifying that the target battery does not present a safety risk due to lithium deposition during charging;

[0104] A first acquisition module 802 is used to acquire the battery impedance of the target battery during the charging process when a calibration task needs to be performed;

[0105] An acquisition module 803 is used to obtain an impedance change rate curve of a target battery according to all battery impedances, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power;

[0106] A first determination module 804 is used to determine the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve;

[0107] The control module 805 is used to control the charging terminal of the target battery to perform the charging task according to the maximum charging capacity.

[0108] In an optional embodiment, the judging module includes:

[0109] A first acquisition submodule is used to acquire target data of a target battery, wherein the target data is data related to the usage time, charging environment temperature, or charge and discharge times of the target battery;

[0110] The first determination submodule is used to determine that a verification task needs to be performed when the target data is not within a preset safety interval.

[0111] In an optional embodiment, the first acquisition module includes:

[0112] A control submodule, configured to intermittently charge the target battery according to a preset charging rate curve when the current remaining power of the target battery is lower than a preset first power threshold, wherein the charging rate curve is a curve in which the charging rate varies with the remaining power;

[0113] A first obtaining submodule, used for obtaining a charging current and a first charging voltage and a second charging voltage before and after a rest period according to data collected by the target battery during intermittent charging;

[0114] The second obtaining submodule is used to obtain the battery impedance of the target battery at the corresponding charging rate according to the charging current, the first charging voltage and the second charging voltage.

[0115] In an optional embodiment, the control submodule includes:

[0116] a first control unit, configured to perform intermittent charging of the target battery at room temperature according to charging parameters represented by a charging rate curve when the charging environment temperature of the target battery is greater than a preset temperature threshold, until the remaining power of the target battery reaches a first target power when the battery is fully charged;

[0117] The second control unit is used to perform low-temperature intermittent charging on the target battery according to the charging parameters represented by the charging rate curve when the charging environment temperature is less than or equal to the temperature threshold, and to charge with a charging current lower than the current threshold after charging is cut off until the remaining power of the target battery reaches a second target power when the battery is fully charged.

[0118] In an optional embodiment, the first acquisition module further includes:

[0119] The second acquisition submodule is used to obtain the corresponding relationship between different charging currents and charging amounts during low-temperature intermittent charging;

[0120] A second determination submodule is used to determine the charging current greater than the preset second power threshold in the corresponding relationship as the adaptation current that meets the low temperature charging condition;

[0121] The judgment submodule is used to judge whether the target battery will experience a secondary reduction in impedance when all the adapted currents are used for low-temperature intermittent charging;

[0122] The third determination submodule is used to determine the corresponding adaptation current as the target current for implementing low-temperature intermittent charging when it is determined that the target battery will not experience a secondary impedance reduction phenomenon.

[0123] In an optional embodiment, the impedance change rate curve includes a first change rate curve obtained when the charging environment temperature is greater than a temperature threshold, and a second change rate curve obtained when the charging environment temperature is less than or equal to the temperature threshold; the first determination module includes:

[0124] A fourth determination submodule is used to extract a minimum change rate of the battery impedance from the data represented by the first change rate curve, and determine the minimum change rate as a change rate threshold for safe charging;

[0125] A fifth determination submodule, configured to determine the remaining power corresponding to the change rate threshold in the second change rate curve as a safe charge capacity;

[0126] The sixth determination submodule is used to determine a safe charge amount that is greater than a preset third charge threshold as a maximum charge amount.

[0127] In an optional embodiment, the control device further includes:

[0128] A second acquisition module is used to acquire the maximum charge capacity of the target battery under the target condition for the first time, wherein the target condition is a charging condition when the charging environment temperature is lower than the temperature threshold and the charging rate is higher than the rate threshold;

[0129] A second determination module is used to determine the maximum number of charge and discharge times of the target battery under the target conditions according to the maximum charge capacity under the target conditions;

[0130] The processing module is used to record and warn the charging times of the target battery according to the maximum charging and discharging times when the target battery is charged under the target conditions.

[0131] Based on the same technical concept as the control method, an embodiment of the present invention also provides an electronic device, including a processor and a memory, wherein the memory is coupled to the processor and stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of any one of the control methods.

[0132] Based on the same technical concept as the control method, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of any one of the control methods are implemented.

[0133] The technical solution provided in the embodiments of the present invention has at least the following technical effects or advantages:

[0134] 1. When it is determined that a verification task needs to be performed, the battery impedance of the target battery during the charging process is obtained. The verification task is to verify that the target battery does not present a safety risk due to lithium plating during charging; the impedance change rate curve of the target battery is obtained based on all battery impedances. Since the impedance change rate curve is a curve of the impedance change rate of the target battery as the remaining power changes, the maximum charging amount of the target battery for safe charging can be further determined based on the impedance change rate curve. Based on the maximum charging amount, the target battery will not present a safety risk due to lithium plating during charging. When the charging terminal that controls the target battery based on the maximum charging amount performs the charging task, the safety risk impact of lithium plating on battery charging can be effectively reduced, thereby improving the safety of the battery charging process.

[0135] 2. A non-destructive in-situ detection method for batteries in extreme working conditions such as low-temperature fast charging is proposed. This method supplements the SOC through microcurrent and combines pulse current to test the battery impedance in the high SOC state of the battery. The overall method is simple to operate and can reflect the detection results in real time. It also solves the problem that the intermittent charging method is not applicable in extreme working conditions, lacks data on key SOC states, and cannot accurately reflect the state nodes where lithium deposition occurs. It can accurately determine the occurrence of lithium deposition behavior and predict the battery life attenuation after experiencing low-temperature fast charging conditions, and has reliable feasibility.

[0136] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0137] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (modules, systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0138] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0139] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0140] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0141] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A battery charging control method, characterized in that: The method comprises: Determine whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is a task of verifying that the target battery does not present a safety risk due to lithium deposition during charging; When the verification task needs to be performed, obtaining the battery impedance of the target battery during the charging process; Obtaining an impedance change rate curve of the target battery according to all battery impedances, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power; Determining a maximum charge capacity of the target battery for safe charging according to the impedance change rate curve; The charging terminal of the target battery is controlled to perform a charging task according to the maximum charging amount.

2. The battery charging control method according to claim 1, characterized in that: The step of determining whether it is necessary to perform a safe charging verification task on the target battery includes: Acquire target data of the target battery, wherein the target data is data associated with the usage time, charging environment temperature, or charge and discharge times of the target battery; When the target data is not within a preset safety interval, it is determined that the verification task needs to be performed.

3. The battery charging control method according to claim 1, characterized in that: The obtaining of the battery impedance of the target battery during the charging process includes: When the current remaining power of the target battery is lower than a preset first power threshold, intermittently charging the target battery according to a preset charging rate curve, wherein the charging rate curve is a curve showing a change in charging rate with the remaining power; Obtaining a charging current and a first charging voltage and a second charging voltage before and after a rest period according to data collected from the target battery during intermittent charging; A battery impedance of the target battery at a corresponding charging rate is obtained according to the charging current, the first charging voltage, and the second charging voltage.

4. The battery charging control method according to claim 3, characterized in that: The intermittent charging of the target battery according to a preset charging rate curve includes: When the charging environment temperature of the target battery is greater than a preset temperature threshold, the target battery is intermittently charged at room temperature according to the charging parameters represented by the charging rate curve until the remaining power of the target battery reaches a first target power when the battery is fully charged; When the charging environment temperature is less than or equal to the temperature threshold, the target battery is intermittently charged at low temperature according to the charging parameters represented by the charging rate curve, and is charged with a charging current lower than the current threshold after charging is terminated until the remaining power of the target battery reaches a second target power when the battery is fully charged.

5. The battery charging control method according to claim 4, characterized in that: Before performing low-temperature intermittent charging on the target battery according to the charging parameters represented by the charging rate curve, the method further includes: Obtaining the corresponding relationship between different charging currents and charging amounts during the low-temperature intermittent charging process; Determine the charging current greater than the preset second power threshold in the corresponding relationship as the adaptation current that meets the low-temperature charging condition; Determining whether the low-temperature intermittent charging using all the adapted currents will cause a secondary reduction in impedance of the target battery; If not, the corresponding adaptation current is determined as the target current for implementing the low-temperature intermittent charging.

6. The battery charging control method according to claim 1, characterized in that: The impedance change rate curve includes a first change rate curve corresponding to when the charging environment temperature is greater than a temperature threshold, and a second change rate curve corresponding to when the charging environment temperature is less than or equal to the temperature threshold; determining the maximum charge amount of the target battery for safe charging according to the impedance change rate curve includes: Extracting a minimum change rate of the battery impedance from the data represented by the first change rate curve, and determining the minimum change rate as a change rate threshold for safe charging; Determining the remaining power corresponding to the change rate threshold in the second change rate curve as a safe charging capacity; A safe charge amount that is greater than a preset third charge threshold is determined as the maximum charge amount.

7. The battery charging control method according to claim 1, characterized in that: After determining the maximum charge capacity of the target battery for safe charging according to the impedance change rate curve, the method further includes: Obtaining the maximum charge capacity of the target battery under target conditions for the first time, wherein the target conditions are charging conditions when the charging environment temperature is lower than a temperature threshold and the charging rate is higher than a rate threshold; Determining the maximum number of charge and discharge times of the target battery under the target condition according to the maximum charge capacity under the target condition; When the target battery is charged under the target condition, the charging times of the target battery are recorded and an alarm is issued according to the maximum charging and discharging times.

8. A battery charging control device, characterized in that: The device comprises: A judgment module, used to judge whether it is necessary to perform a safe charging verification task on the target battery, wherein the verification task is a task of verifying that the target battery does not present a safety risk due to lithium deposition during charging; A first acquisition module, used for acquiring the battery impedance of the target battery during the charging process when the verification task needs to be performed; An acquisition module, used for acquiring an impedance change rate curve of the target battery according to all battery impedances, wherein the impedance change rate curve is a curve showing that the impedance change rate of the target battery changes with the remaining power; A first determination module, configured to determine a maximum charge capacity of the target battery for safe charging according to the impedance change rate curve; A control module is used to control the charging terminal of the target battery to perform a charging task according to the maximum charging amount.

9. An electronic device, characterized in that: The electronic device comprises a processor and a memory, wherein the memory is coupled to the processor and stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 7 are implemented.

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