Method and device for estimating battery pack power limit, and battery management system

Abstract

A method for estimating a battery pack power limit value, comprising: obtaining an actual minimum single cell voltage of a minimum voltage cell in a battery pack (S110); obtaining a static discharge power limit value of the battery pack (S120); calculating an estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit value according to the actual minimum single cell voltage (S130); determining whether the estimated discharge voltage is located between a discharge voltage control threshold of the minimum voltage cell and an under-voltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the under-voltage threshold (S140); when located between the discharge voltage control threshold and the under-voltage threshold, determining a target discharge power limit value of the battery pack according to the estimated discharge voltage, the static discharge power limit value, the discharge voltage control threshold, the under-voltage threshold and a minimum power limit value of a whole vehicle through a discharge interpolation algorithm (S150). The power control during vehicle operation is realized, and under-voltage or over-voltage is avoided.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of battery, in particular to a battery pack power limit value estimation method and device and a battery management system. BACKGROUND

[0002] Battery power limit value estimation is an important function of the battery management system of a power automobile. Through battery power limit value estimation, the power automobile can be reasonably used, overvoltage or undervoltage situations can be avoided, and the service life of the battery pack can be prolonged.

[0003] In the existing battery pack power limit value estimation method, the battery pack power limit value is usually estimated according to the state of charge value of the battery and the parameters of the battery cell. However, the inventors have found that this requires switching between multiple tables. During the discharging or charging process of the battery pack, if the cumulative power of the whole vehicle is greater than a certain duration Map table for more than a calibration time, a Map table with a longer duration corresponding to the current used Map table is used to look up to obtain the limit value power. This method has no clear calculation meaning. If the calibration time is small, the margin is too large, and if the calibration time is large, the limit is too strict, and the given value will repeatedly jump between two Map tables. Moreover, factors such as varying working conditions, Map accuracy errors, inconsistencies of battery cells, and aging of battery cells can easily cause the battery to be in an undervoltage situation. Therefore, how to properly control the voltage and avoid undervoltage or overvoltage is a technical problem to be solved. SUMMARY

[0004] In view of the above problems, embodiments of the present application provide a battery pack power limit value estimation method, device and battery management system to solve the problem of undervoltage or overvoltage caused by inaccurate power limit value estimation in the prior art.

[0005] According to an aspect of an embodiment of the present application, a battery pack power limit value estimation method is provided, the method comprising:

[0006] obtaining an actual single cell minimum voltage of a minimum voltage battery cell in a battery pack;

[0007] obtaining a static discharge power limit value of the battery pack;

[0008] calculating an estimated discharge voltage of the minimum voltage battery cell when the battery pack is discharged according to the static discharge power limit value according to the actual single cell minimum voltage;

[0009] determining whether the estimated discharge voltage is located between a discharge voltage control threshold of the minimum voltage battery cell and an undervoltage threshold of the minimum voltage battery cell; the discharge voltage control threshold is greater than the undervoltage threshold;

[0010] When the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell, a target discharge power limit value of the battery pack is determined by a discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit value, the discharge voltage control threshold, the under-voltage threshold, and the vehicle minimum power limit value.

[0011] In an optional manner, the static discharge power limit value of the battery pack is obtained by: obtaining a minimum state of charge value of the cells in the battery pack; obtaining a first temperature of the battery pack; and querying a preset first correspondence table of state of charge, temperature, and discharge power to obtain the static discharge power limit value of the battery pack according to the minimum state of charge value and the first temperature of the battery pack.

[0012] In an optional manner, the estimated discharge voltage of the minimum voltage cell of the battery pack when the battery pack is discharged according to the static discharge power limit value is calculated according to the actual minimum voltage of the single cell.

[0013] The actual minimum voltage of the minimum voltage cell, the actual discharge current of the minimum voltage cell, and the discharge state internal resistance corresponding to the minimum voltage cell in the battery pack are obtained.

[0014] The discharge current limit value of the battery pack is determined according to the static discharge power limit value.

[0015] The estimated discharge voltage of the minimum voltage cell is determined according to the actual minimum voltage of the single cell, the actual discharge current of the minimum voltage cell, the discharge current limit value of the battery pack, and the discharge state internal resistance of the minimum voltage cell.

[0016] In an optional manner, when the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell, a target discharge power limit value of the battery pack is determined by a discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit value, the discharge voltage control threshold, the under-voltage threshold, and the vehicle minimum power limit value, including: taking a difference between the estimated discharge voltage and the under-voltage threshold as an input difference term of a PID algorithm to obtain a discharge correction term; correcting the discharge interpolation algorithm according to the discharge correction term; and calculating the target discharge power limit value of the battery pack by using the corrected discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit value, the discharge voltage control threshold, the under-voltage threshold, and the vehicle minimum power limit value.

[0017] In an optional manner, the corrected discharge interpolation algorithm is:

[0018]

[0019] Among them, P max represents the target discharge power limit of the battery pack; P 静 Represents the static discharge power limit of the battery pack; P min Indicates the minimum power limit of the vehicle; V tg100 is the discharge voltage control threshold of the minimum voltage cell; V tg0 is the undervoltage threshold of the minimum voltage cell; ΔV 修 represents a discharge correction term calculated based on the estimated discharge voltage and the undervoltage threshold.

[0020] According to another aspect of an embodiment of the present application, a method for estimating a battery pack power limit is provided, the method comprising:

[0021] Get the actual maximum voltage of the maximum voltage cell in the battery pack;

[0022] Obtaining a static charging power limit of the battery pack;

[0023] Calculating, based on the actual maximum cell voltage, an estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit;

[0024] determining whether the estimated charging voltage is between a charging voltage control threshold of the maximum voltage battery cell and an overvoltage threshold of the maximum voltage battery cell; the charging voltage control threshold is less than the overvoltage threshold;

[0025] When the estimated charging voltage is between the charging voltage control threshold of the maximum voltage battery cell and the overvoltage threshold of the maximum voltage battery cell, the target charging power limit of the battery pack is determined by a charging interpolation algorithm based on the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold and the minimum power limit of the vehicle.

[0026] In an optional manner, obtaining the static charging power limit of the battery pack includes: obtaining the maximum state of charge value of the battery cells in the battery pack and the second temperature of the battery pack; and according to the maximum state of charge value and the second temperature of the battery pack, querying in a second correspondence table of preset state of charge, temperature and charging power to obtain the static charging power limit.

[0027] In an alternative manner, the calculating the estimated charging voltage of the maximum voltage cell of the battery pack when the battery pack is charged according to the static charging power limit value comprises: obtaining the actual single maximum voltage of the cell in the battery pack, the actual charging current of the maximum voltage cell, and the corresponding charging state internal resistance of the maximum voltage cell; determining the charging current limit value of the battery pack according to the static charging power limit value of the battery pack; determining the estimated charging voltage according to the actual single maximum voltage, the actual charging current, the charging current limit value, and the charging state internal resistance.

[0028] In an alternative manner, when the estimated charging voltage is between the charging voltage control threshold value of the maximum voltage cell and the overvoltage threshold value of the maximum voltage cell, the target charging power limit value of the battery pack is determined by a charging interpolation algorithm according to the estimated charging voltage, the static charging power limit value, the charging voltage control threshold value, the overvoltage threshold value, and the minimum power limit value of the whole vehicle, which comprises: taking the difference between the estimated charging voltage and the overvoltage threshold value of the maximum voltage cell as an input difference term of the PID algorithm to obtain a charging correction term; correcting the charging interpolation algorithm according to the charging correction term; and calculating the target charging power limit value of the battery pack by using the corrected charging interpolation algorithm according to the estimated charging voltage, the static charging power limit value, the charging voltage control threshold value, the overvoltage threshold value, and the minimum power limit value of the whole vehicle.

[0029] In an alternative manner, the corrected charging interpolation algorithm is:

[0030]

[0031] wherein, P' max represents the target charging power limit value of the battery pack; P' 静 represents the static charging power limit value of the battery pack; P' min represents the minimum power limit value of the whole vehicle; V' tg100 is the charging voltage control threshold value of the maximum voltage cell; V' tg0 is the overvoltage threshold value of the maximum voltage cell; ΔV' 修 represents the charging correction term calculated according to the estimated charging voltage and the overvoltage threshold value.

[0032] According to another aspect of the embodiments of the present application, a battery pack power limit value estimation device is provided, which comprises:

[0033] a first obtaining module configured to obtain the actual single minimum voltage of the minimum voltage cell in the battery pack;

[0034] a second obtaining module configured to obtain the static discharging power limit value of the battery pack;

[0035] The first calculating module is configured to calculate an estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit value based on the actual single cell minimum voltage.

[0036] The first determining module is configured to determine whether the estimated discharge voltage is between a discharge voltage control threshold of the minimum voltage cell and an under-voltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the under-voltage threshold.

[0037] The second determining module is configured to determine a target discharge power limit value of the battery pack by a discharge interpolation algorithm based on the estimated discharge voltage, the static discharge power limit value, the discharge voltage control threshold, the under-voltage threshold and a minimum power limit value of the whole vehicle when the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell.

[0038] According to another aspect of the embodiments of the present application, a battery pack power limit value estimation device is provided, which comprises:

[0039] The third acquiring module is configured to acquire an actual single cell maximum voltage of a maximum voltage cell in the battery pack.

[0040] The fourth acquiring module is configured to acquire a static charge power limit value of the battery pack.

[0041] The second calculating module is configured to calculate an estimated charge voltage of the maximum voltage cell when the battery pack is charged according to the static charge power limit value based on the actual single cell maximum voltage.

[0042] The third determining module is configured to determine whether the estimated charge voltage is between a charge voltage control threshold of the maximum voltage cell and an over-voltage threshold of the maximum voltage cell; the charge voltage control threshold is less than the over-voltage threshold.

[0043] The fourth determining module is configured to determine a target charge power limit value of the battery pack by a charge interpolation algorithm based on the estimated charge voltage, the static charge power limit value, the charge voltage control threshold, the over-voltage threshold and a minimum power limit value of the whole vehicle when the estimated charge voltage is between the charge voltage control threshold of the maximum voltage cell and the over-voltage threshold of the maximum voltage cell.

[0044] According to another aspect of the embodiments of the present application, a battery management system is provided, comprising a processor, a memory, a communication interface and a communication bus, the processor, the memory and the communication interface complete communication with each other through the communication bus; the memory is used to store at least one executable instruction, and the executable instruction causes the processor to execute the operations of the battery pack power limit value estimation method.

[0045] According to another aspect of the embodiments of the present application, a power automobile is provided, comprising the battery management system.

[0046] According to another aspect of the embodiments of the present application, a computer readable storage medium is provided, and the computer readable storage medium stores at least one executable instruction, and the executable instruction causes the battery pack power limit value estimation device to execute the operations of the battery pack power limit value estimation method when the battery pack power limit value estimation device runs.

[0047] The embodiments of the present application calculate the estimated voltage, which is closer to the voltage range that the battery cell can use at the next time, so that the estimation of the power limit value is more accurate. Meanwhile, when the estimated voltage is in the preset threshold range, the embodiments of the present application calculate the power limit value in the preset threshold range by using the interpolation algorithm, which can adapt to the power limit value control under complex working conditions and accurately and reasonably estimate the power limit value, so that the power change in the vehicle control process is smooth.

[0048] The above description is only a summary of the technical solutions of the embodiments of the present application, in order to more clearly understand the technical means of the embodiments of the present application, the embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the embodiments of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings are only used to show the embodiments, and are not considered as limitations of the present application. Moreover, the same reference signs are used to represent the same parts throughout the drawings. In the drawings:

[0050] Figure 1 A flowchart of a battery pack power limit value estimation method provided by the embodiments of the present application is shown;

[0051] Figure 2 A flowchart of a battery pack power limit value estimation method provided by another embodiment of the present application is shown;

[0052] Figure 3 A structure diagram of a battery pack power limit value estimation device provided by the embodiments of the present application is shown;

[0053] Figure 4 Fig. 1 shows a structural schematic diagram of a battery pack power limit estimation device according to an embodiment of the present application;

[0054] Figure 5 Fig. 2 shows a structural schematic diagram of a battery management system according to an embodiment of the present application. DETAILED DESCRIPTION

[0055] Exemplary embodiments of the present application will be described in detail with reference to the drawings. Although exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0056] Figure 1 Fig. 3 shows a flow chart of a battery pack power limit estimation method according to an embodiment of the present application. The method is executed by a battery management system, which can be a battery management system in a power vehicle. As shown in Fig. 3, the method is used for controlling the discharge power during vehicle operation, for example, the discharge power during vehicle starting or acceleration. The method comprises the following steps: Figure 1

[0057] S110: Obtain the actual minimum voltage of the minimum voltage cell in the battery pack.

[0058] The minimum voltage cell in the battery pack refers to the cell with the minimum voltage in the battery pack. The actual minimum voltage of the minimum voltage cell in the battery pack is the voltage value corresponding to the cell with the actual minimum voltage in the battery pack. The actual minimum voltage is obtained by real-time measurement by the battery management system.

[0059] S120: Obtain the static discharge power limit of the battery pack.

[0060] In the embodiment of the present application, the static discharge power limit of the battery pack is obtained according to the corresponding relationship between the temperature, the state of charge (SOC, range 0-100) and the discharge power limit of the battery pack. Specifically, the battery management system obtains the minimum state of charge value of the cell in the battery pack as the SOC of the battery pack; and obtains the first temperature of the battery pack. According to the minimum state of charge value and the first temperature of the battery pack, the static discharge power limit of the battery pack is obtained by querying a preset first corresponding relationship table of SOC, temperature and discharge power. The first temperature is the temperature of the battery pack at the current time.

[0061] S130: Calculate the estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit according to the actual minimum voltage of the minimum voltage cell.

[0062] ​The battery pack power limit estimation method of the embodiments of the present application is used for power control during vehicle operation, and thus needs to determine the discharge power limit of the next time period according to the voltage state of the minimum voltage cell of the battery pack. The cell discharge voltage is the voltage corresponding to the discharge current of the battery pack cell. Due to the characteristics of the battery itself, if the cell is discharged with a pulse current at the next moment, the part of the cell discharge voltage (ohmic voltage drop) included in the voltage of the cell will immediately decrease in a very short time, and thus this part of voltage drop cannot be used as a basis for calculating the pulse allowable value (target discharge power limit) later. If the actual single minimum voltage is directly used as an input item to calculate the discharge power limit, the calculated discharge power limit is greater than the true discharge power limit, which is easy to cause under-voltage. Therefore, the voltage of the minimum voltage cell of the battery pack needs to be estimated to determine the estimated discharge voltage of the minimum voltage cell. The steps of the estimation specifically include:

[0063] S1301: Obtain the actual single minimum voltage of the minimum voltage cell in the battery pack, the actual discharge current of the minimum voltage cell, and the discharge state internal resistance corresponding to the minimum voltage cell. Since the batteries in the battery pack are connected in series to form the battery pack, the actual discharge current of the minimum voltage cell is the actual current of the battery pack, which can be measured by the battery management system, and the actual discharge current is positive during discharge. The discharge state internal resistance of the minimum voltage cell can be obtained by querying a preset correspondence table of state of charge, temperature and state internal resistance according to the minimum state of charge value and the first temperature of the battery pack. The time corresponding to the discharge state internal resistance of the minimum voltage cell can be a preset time length such as 2s, 5s, etc.

[0064] S1302: Determine the discharge current limit of the battery pack according to the static discharge power limit of the battery pack. The discharge current limit of the battery pack corresponds to the static discharge power limit of the battery pack, and the discharge current limit of the battery pack can be determined according to the correspondence. The discharge current limit of the battery pack can be calculated according to the power formula, or can be found according to a preset relationship table.

[0065] In the embodiments of the present application, the discharge current limit of the battery pack can be calculated according to the following power formula:

[0066] P 静 =I 总限值 *U 实际

[0067] Wherein, P 静 is the static discharge power limit of the battery pack; I 总限值 is the discharge current limit of the battery pack; U 实际The actual voltage of the battery pack is calculated, and can also be determined by looking up a preset relationship table of static discharge power limit, discharge current limit and voltage. Since each cell in the battery pack is connected in series, the actual voltage of the battery pack is the sum of the actual voltages of each cell; the discharge current limit of the battery pack is the same as the discharge current limit of the cell.

[0068] S1303: Determine the estimated discharge voltage of the minimum voltage cell according to the actual single minimum voltage of the minimum voltage cell, the actual discharge current of the minimum voltage cell, the discharge current limit of the minimum voltage cell and the discharge state internal resistance of the minimum voltage cell. In the embodiments of the present application, the estimated discharge voltage is determined by the following formula:

[0069] V 预估 = V 实际 +(I 实际 -I 限值 )*DCR

[0070] Wherein, V 预估 is the estimated discharge voltage of the minimum voltage cell, V 实际 is the actual single minimum voltage of the minimum voltage cell, I 实际 is the actual discharge current of the minimum voltage cell, I 限值 is the discharge current limit of the minimum voltage cell, and DCR is the discharge state internal resistance of the minimum voltage cell.

[0071] In the embodiments of the present application, for the acceleration scenario during the vehicle operation, the battery pack is continuously in a discharge state, and the estimated voltage of the battery pack can be determined by the above formula. For the scenario when the vehicle starts, the actual single minimum voltage is the single open circuit voltage (OCV) of the minimum voltage cell in the battery pack. It can be obtained by querying the corresponding relationship table of state of charge, temperature and open circuit voltage. At the initial stage of vehicle starting, no actual discharge current is generated, so I 实际 is 0. Therefore, the calculation formula of the estimated discharge voltage of the minimum voltage cell is transformed as follows:

[0072] V 预估 = OCV+I 限值 *DCR

[0073] Wherein, OCV is the single open circuit voltage of the minimum voltage cell in the battery pack, I 限值 is the discharge current limit of the battery pack, and DCR is the discharge state internal resistance of the minimum voltage cell in the battery pack.

[0074] The above calculation method of the estimated voltage of the minimum cell voltage makes the estimated voltage closer to the voltage range that can be used by the minimum voltage cell in the battery pack at the next moment, so that the subsequent calculation of the discharge power limit of the battery pack is more accurate and reasonable.

[0075] S140: determining whether the estimated discharge voltage of the minimum voltage cell is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the under-voltage threshold.

[0076] In the embodiments of the present application, the discharge voltage control threshold of the minimum voltage cell is set, that is, when the estimated discharge voltage is less than the discharge voltage control threshold and greater than the under-voltage threshold, the calculation of the discharge power limit value is performed.

[0077] The purpose of this is that when the single cell voltage of the minimum voltage cell in the battery pack is large, it is less likely to appear under-voltage. When the single cell voltage of the minimum voltage cell in the battery pack decreases, the probability of under-voltage increases. Therefore, when the single cell voltage of the minimum voltage cell in the battery pack is large, the determination of the target discharge power limit value can be performed by the existing table lookup or other methods, and when the single cell voltage of the minimum voltage cell in the battery pack decreases to be less than or equal to the discharge voltage control threshold of the minimum voltage cell, the determination of the target discharge power limit value of the battery pack is performed by the battery pack power limit value estimation method of the embodiments of the present application, so that the determination of the discharge power limit value is more reasonable and accurate. Therefore, the embodiments of the present application set the discharge voltage control threshold as the control trigger condition. The specific value of the discharge voltage control threshold is not specifically limited in the embodiments of the present application, and those skilled in the art can make corresponding settings according to the specific application scenarios and battery pack parameters. In an embodiment of the present application, the discharge voltage control threshold can be the static single cell open-circuit voltage of the minimum voltage cell at 0SOC (i.e., the state of charge value is 0). The static single cell open-circuit voltage at 0SOC can be determined according to the temperature of the minimum voltage cell, for example, the single cell open-circuit voltage of the minimum voltage cell at 0SOC is 3.3V, and the discharge voltage control threshold is 3.3V, which is about 200mV greater than the true under-voltage threshold of the minimum voltage cell.

[0078] In the embodiments of the present application, the under-voltage threshold can be the true under-voltage threshold of the minimum voltage cell in the battery pack, or can be slightly greater than the true under-voltage threshold.

[0079] S150: when the estimated discharge voltage of the minimum voltage cell is between the discharge voltage control threshold and the under-voltage threshold, the target discharge power limit value of the battery pack is determined by a discharge interpolation algorithm according to the estimated discharge voltage of the minimum voltage cell, the static discharge power limit value of the battery pack, the discharge voltage control threshold of the minimum voltage cell, the under-voltage threshold of the minimum voltage cell, and the minimum power limit value of the whole vehicle.

[0080] Wherein, since each cell in the battery pack is in series, the discharge current of the cells in the battery pack is determined by the voltage of the minimum voltage cell, and thus the target discharge power limit of the battery pack is limited by the minimum voltage cell. Therefore, according to the proportional relationship between the estimated voltage of the minimum voltage cell and the under-voltage threshold and the discharge voltage control threshold, the proportional relationship between the target discharge power limit and the static discharge power limit and the minimum power limit of the vehicle can be determined, so as to determine the target discharge power limit.

[0081] In the embodiments of the present application, the target discharge power limit of the battery pack can be determined by the following discharge interpolation algorithm:

[0082]

[0083] The discharge interpolation algorithm is a linear interpolation algorithm. Wherein, P max represents the target discharge power limit of the battery pack; P 静 represents the static discharge power limit of the battery pack; P min represents the minimum power limit of the vehicle; V tg100 is the discharge voltage control threshold of the minimum voltage cell; V tg0 is the under-voltage threshold of the minimum voltage cell; V 预估 represents the estimated discharge voltage of the minimum voltage cell.

[0084] In another embodiment of the present application, the target discharge power limit of the battery pack is determined by a discharge interpolation algorithm according to the estimated discharge voltage of the minimum voltage cell, the static discharge power limit of the battery pack, the discharge voltage control threshold of the minimum voltage cell, the under-voltage threshold of the minimum voltage cell, and the minimum power limit of the vehicle, including the following steps:

[0085] S1501: Taking the difference between the estimated discharge voltage of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell as the input difference term of the PID algorithm, to obtain a discharge correction term.

[0086] Wherein, the discharge correction term is determined by the following formula:

[0087] ΔV 修 = k p *(V 预估 -V tg0 ) + k i *(V 预估 -V tg0 ) integral term + k d *(V 预估 -V tg0 ) change

[0088] PID algorithm is: in process control, according to the deviation of proportion (P), integral (I) and differential (D) calculation, to realize the input detection, output control, output control can affect the input detection, so that the detection can close to the target value. Generally speaking, the control object has inertia, not instantaneity. PID is divided into three parts: proportional (k p * difference), integral (k i * past time difference and), differential (k d * difference rate). The above difference refers to the difference between the detection and the control target. In the embodiment of the application, the discharge correction term is calculated according to the estimated discharge voltage and the under voltage threshold, which is a correction to (V 预估 -V tg0 ) in the interpolation formula.

[0089] S1502: according to the discharge correction term to correct the discharge interpolation algorithm.

[0090] In the embodiment of the application, the discharge interpolation algorithm is corrected according to the discharge correction term, and the corrected interpolation algorithm is:

[0091]

[0092] wherein, for ΔV 修 k p , k i , k d , wherein k p is not 0, k i , k d may be 0. That is, according to the specific scene, only k p as a parameter term, or k p , k i , k d as a parameter term. When k p is 1, k i , k d are 0, that is, the interpolation algorithm is not corrected. In the embodiment of the application, the specific value of k p , k i , k d may be calibrated according to the specific scene. For example, according to the corresponding relationship between the estimated discharge voltage of the minimum voltage battery and the target power limit value of the battery pack before the preset scene, the corrected interpolation algorithm is calibrated.

[0093] S1503: According to the estimated discharge voltage of the minimum voltage cell, the static discharge power limit value of the battery pack, the discharge voltage control threshold value of the minimum voltage cell, the under-voltage threshold value of the minimum voltage cell, and the vehicle minimum power limit value, the target discharge power limit value of the battery pack is calculated by using the corrected discharge interpolation algorithm.

[0094] The embodiments of the present application correct the interpolation algorithm, so that the target discharge power limit value of the battery pack calculated is more accurate and reasonable, the voltage can be well controlled, and under-voltage can be avoided.

[0095] In the embodiments of the present application, after obtaining the target discharge power limit value, the following steps are further included:

[0096] S160: Output the target discharge power limit value to the controller of the vehicle for controlling the discharge power during the running process of the vehicle.

[0097] The controller of the vehicle can be a VCU (Vehicle Control Unit) or an ECU (Electronic Control Unit). According to the target discharge power limit value, the controller controls the discharge power when starting or accelerating, so that the voltage can be well controlled during the control process, under-voltage can be avoided, and the discharge power changes smoothly or even stably, so that the vehicle can start or accelerate smoothly even in harsh working conditions.

[0098] The battery pack power limit value estimation method of the embodiments of the present application calculates the estimated discharge voltage of the minimum voltage cell in the battery pack, which is closer to the voltage range that can be used by the minimum voltage cell in the battery pack at the next time, so that the estimation of the target discharge power limit value is more accurate. At the same time, when the estimated discharge voltage is in the preset threshold value interval, the interpolation algorithm is used to calculate the target power limit value in the preset threshold value interval, which can accurately and reasonably estimate the power limit value, so that the voltage can be well controlled even in harsh working conditions, under-voltage can be avoided, and the discharge power changes smoothly during the control process of the vehicle.

[0099] Figure 2 A flowchart of another embodiment of a battery pack power limit value estimation method of the present application is shown, which is performed by a battery management system, which can be a battery management system in a power automobile. As shown in Figure 2 The method is used for controlling the charging power during the running process of the vehicle, for example, the charging power during the brake regenerative process. The method includes the following steps:

[0100] S210: Obtain the actual single maximum voltage of the maximum voltage cell in the battery pack.

[0101] The maximum voltage cell in the battery pack refers to the single cell with the maximum voltage in the battery pack. The actual single maximum voltage of the cells in the battery pack is the voltage value corresponding to the single cell with the actual maximum voltage in the battery pack. The actual single maximum voltage is obtained by real-time measurement by the battery management system.

[0102] S220: Obtain the static charging power limit value of the battery pack.

[0103] In the embodiments of the present application, the static charging power limit value of the battery pack is obtained according to the correspondence between the temperature, the state of charge (SOC) and the charging power limit value of the battery pack. Specifically, the battery management system can obtain the state of charge of the cells in the battery pack as the SOC of the battery pack, and obtain the second temperature of the battery pack. According to the state of charge and the second temperature of the battery pack, the static charging power limit value of the battery pack is obtained by querying a preset second correspondence table of SOC, temperature and charging power. The second temperature is the temperature of the battery pack at the current time.

[0104] S230: Calculate the estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit value according to the actual single maximum voltage.

[0105] In the embodiments of the present application, the estimation method of the battery pack power limit value is used for power control during vehicle operation, and therefore the target charging power limit value of the next time period needs to be determined according to the voltage state of the battery pack. The cell charging voltage is the voltage corresponding to the charging current of the cells in the battery pack. Due to the characteristics of the battery itself, if the next moment is charged with a pulse current, the part of the cell charging voltage (ohmic voltage drop) included in the voltage of the cell will immediately increase in a very short time, and therefore this part of the voltage drop cannot be used as a basis for calculating the pulse allowable value (target charging power limit value) later. If the actual single maximum voltage is directly used as an input item to calculate the target charging power limit value, the calculated target charging power limit value will be greater than the true charging power limit value, which is easy to cause overcharging of the battery pack and cause overvoltage. Therefore, the voltage state of the battery pack needs to be estimated. The steps of the estimation specifically include:

[0106] S2301: Obtain the actual single maximum voltage of the maximum voltage cell in the battery pack, the actual charging current of the maximum voltage cell, and the charging state internal resistance corresponding to the maximum voltage cell. The actual charging current of the maximum voltage cell is the actual charging current of the battery pack, which can be measured by the battery management system. The actual charging current is negative during charging. The charging state internal resistance of the maximum voltage cell can be obtained by querying the preset correspondence table of state of charge, temperature and state internal resistance according to the maximum state of charge value of the maximum voltage cell in the battery pack and the second temperature of the battery pack. The time corresponding to the charging state internal resistance can be a preset time length such as 2s, 5s, etc.

[0107] S2302: Determine the charging current limit value according to the static charging power limit value of the battery pack. The charging current limit value corresponds to the static charging power limit value of the battery pack, and can be determined according to the correspondence relationship.

[0108] Specifically, the embodiments of the present application can be calculated according to the following formula:

[0109] P′ 静 =I′ 总限值 *U′ 实际

[0110] wherein P′ 静 is the static charging power limit value of the battery pack; I′ 总限值 is the charging current limit value of the battery pack; U′ 实际 is the actual voltage of the battery pack. The actual voltage of the battery pack can also be determined by looking up the preset relationship table of static charging power limit value, charging current limit value and voltage. Since each cell in the battery pack is connected in series, the actual voltage of the battery pack is the sum of the actual voltages of each cell; the charging current limit value of the battery pack is the same as the charging current limit value of the cell.

[0111] S2303: Determine the estimated charging voltage of the maximum voltage cell according to the actual single maximum voltage of the maximum voltage cell, the actual charging current of the maximum voltage cell, the charging current limit value of the battery pack, and the charging state internal resistance of the maximum voltage cell.

[0112] In the embodiments of the present application, the estimated charging voltage is determined by the following formula:

[0113] V′ 预估 =V′ 实际 +(I′ 实际 -I′ 限值 )*DCR′

[0114] wherein V′ 预估 is the estimated charging voltage of the maximum voltage cell, V′ 实际 is the actual single maximum voltage of the maximum voltage cell, I′实际 is the actual charging current of the maximum voltage cell 限值 is the charging current limit of the maximum voltage cell, and DCR' is the charging state internal resistance of the maximum voltage cell.

[0115] In the embodiments of the present application, for the brake regenerative charging scenario during vehicle operation, the battery pack is continuously in a charging state during brake regenerative charging, and the estimated charging voltage of the maximum voltage cell in the battery pack can be determined by the above formula. For the initial stage of vehicle brake regenerative charging, the actual single maximum voltage is the single open circuit voltage (OCV') of the maximum voltage cell in the battery pack. It can be obtained by querying the corresponding relationship table of SOC, temperature and open circuit voltage. At the initial stage of vehicle brake regenerative charging, no actual charging current is generated, so I' 实际 is 0. Therefore, the calculation formula of the estimated charging voltage of the maximum voltage cell is transformed as follows:

[0116] V' 预估 = OCV' + I' 限值 * DCR'

[0117] wherein OCV' is the single open circuit voltage of the maximum voltage cell in the battery pack, I' 限值 is the charging current limit of the maximum voltage cell, and DCR' is the charging state internal resistance of the maximum voltage cell.

[0118] The above calculation method of the estimated voltage of the maximum voltage cell makes the estimated voltage more close to the voltage range that can be used by the maximum voltage cell in the battery pack at the next time, so that the calculation of the subsequent charging power limit is more accurate and reasonable.

[0119] S240: determining whether the estimated charging voltage is located between the charging voltage control threshold of the maximum voltage cell and the overvoltage threshold of the maximum voltage cell; the charging voltage control threshold is less than the overvoltage threshold.

[0120] wherein the embodiments of the present application set the charging voltage control threshold of the maximum voltage cell, that is, when the estimated charging voltage of the maximum voltage cell is greater than the charging voltage control threshold and less than the overvoltage threshold, the calculation of the charging power limit is performed.

[0121] The purpose is that when the single cell voltage of the maximum voltage cell in the battery pack is small, it is less likely to occur overcharge overvoltage. And as the single cell voltage of the maximum voltage cell in the battery pack increases during charging, the probability of overvoltage increases. Therefore, when the maximum single cell voltage of the maximum voltage cell in the battery pack is small, the determination of the target charging power limit value can be performed by the existing table lookup or other methods, and when the single cell voltage of the maximum voltage cell in the battery pack increases to be greater than the charging voltage control threshold, the determination of the target charging power limit value is performed by the battery pack power limit value estimation method of the embodiment of the application, so that the determination of the target charging power limit value is more reasonable and accurate. Therefore, the charging voltage control threshold of the maximum voltage cell is set as the trigger condition for control in the embodiment of the application. The specific value of the charging voltage control threshold is not specifically limited in the embodiment of the application, and a person skilled in the art can make corresponding settings according to the specific application scene and the battery pack parameters. The overvoltage threshold of the embodiment of the application can be the real overvoltage threshold of the battery pack, or can be slightly greater than the real overvoltage threshold. In an embodiment of the application, the charging voltage control threshold can be the open-circuit voltage of the maximum voltage cell at 100 SOC (i.e., the state of charge value is 100%). The static open-circuit voltage at 100 SOC can be determined according to the temperature of the maximum voltage cell, for example, the static open-circuit voltage of the maximum voltage cell at 100 SOC is 4.2V, and the charging voltage control threshold is about 4.2V, which is about 200mV less than the real overvoltage threshold of the maximum voltage cell.

[0122] S250: When the estimated charging voltage is between the charging voltage control threshold of the maximum voltage cell and the overvoltage threshold of the maximum voltage cell, the target charging power limit value of the battery pack is determined by a charging interpolation algorithm according to the estimated charging voltage of the maximum voltage cell, the static charging power limit value of the battery pack, the charging voltage control threshold of the maximum voltage cell, the overvoltage threshold of the maximum voltage cell, and the minimum power limit value of the whole vehicle.

[0123] Since the cells in the battery pack are connected in series, the charging current of the cells in the battery pack is determined by the voltage of the maximum voltage cell, and therefore the target charging power limit of the battery pack is limited by the maximum voltage cell. Therefore, according to the proportional relationship between the estimated voltage of the maximum voltage cell and the overvoltage threshold and the charging voltage control threshold, the proportional relationship between the target charging power limit and the static charging power limit and the minimum power limit of the whole vehicle can be determined, so as to determine the target charging power limit value.

[0124] In the embodiment of the application, the target charging power limit value of the battery pack can be determined by the following charging interpolation algorithm:

[0125]

[0126] The charging interpolation algorithm is a linear interpolation algorithm. Wherein, P' max represents a target charging power limit value of the battery pack; P' 静 represents a static charging power limit value of the battery pack; P' min represents a minimum power limit value of the vehicle; V' tg100 is a charging voltage control threshold value of the maximum voltage cell; V' tg0 is an overvoltage threshold value of the maximum voltage cell; V' 预估 represents an estimated charging voltage of the maximum voltage cell.

[0127] In another embodiment of the present application, according to the estimated charging voltage of the maximum voltage cell, the static charging power limit value of the battery pack, the charging voltage control threshold value of the maximum voltage cell, the overvoltage threshold value of the maximum voltage cell, and the minimum power limit value of the vehicle, the target charging power limit value of the battery pack is determined by a charging interpolation algorithm, comprising the following steps:

[0128] S2501: Taking the difference between the estimated charging voltage of the maximum voltage cell and the overvoltage threshold value of the maximum voltage cell as an input difference term of a PID algorithm, and obtaining a charging correction term.

[0129] Wherein, the charging correction term is determined by the following formula:

[0130] ΔV′ 修 = k' p *(V' 预估 -V' tg0 )+ k' i *(V' 预估 -V' tg0 ) integral term + k' d *(V' 预估 -V' tg0 ) change;

[0131] Wherein, the PID algorithm is: in process control, the proportional (P), integral (I) and differential (D) are calculated according to the deviation, so as to realize the input detection quantity, the output control quantity, and the output control quantity can affect the input detection quantity, so that the detection quantity can approach the target value. Generally speaking, the control object has inertia, not instantaneity. PID is divided into three parts: proportional (k' p * difference), integral (k' i * difference of past period of time), and differential (k' d * change rate of difference). The above difference refers to the difference between the detection quantity and the control target. In the embodiment of the present application, the charging correction term is calculated according to the estimated charging voltage and the overvoltage threshold value, which is the interpolation formula (V' 预估V' tg0 ) the correction term.

[0132] S2502: correcting the charging interpolation algorithm according to the charging correction term.

[0133] In the embodiment of the application, the charging interpolation algorithm is corrected according to the charging correction term, and the corrected interpolation algorithm is:

[0134]

[0135] wherein, for ΔV' 修 The parameter term k' p , k' i , k' d , wherein k' p is not 0, and k' i , k' d may be 0. That is, only k' p may be selected as a parameter term according to a specific scene, or k' p , k' i , k' d may all be selected as parameter terms. When k' p is 1 and k' i , k' d are all 0, that is, the interpolation algorithm is not corrected. In the embodiment of the application, the specific values of k' p , k' i , k' d may be calibrated and trained according to a specific scene. Specifically, the calibrated and trained values may be obtained by the corrected interpolation algorithm according to the corresponding relationship between the estimated charging voltage of the maximum voltage cell and the target power limit value of the battery pack before the preset scene.

[0136] S2503: calculating the target charging power limit value of the battery pack by using the corrected charging interpolation algorithm according to the estimated charging voltage of the maximum voltage cell, the static charging power limit value of the battery pack, the charging voltage control threshold of the maximum voltage cell, the overvoltage threshold of the maximum voltage cell, and the minimum power limit value of the whole vehicle.

[0137] The embodiment of the application corrects the interpolation algorithm, so that the calculated target charging power limit value is more accurate and reasonable, the voltage can be well controlled, and overvoltage can be avoided.

[0138] In the embodiment of the application, after obtaining the target charging power limit value, the following steps are further included:

[0139] S260: outputting the target charging power limit value to the controller of the vehicle for controlling the charging power in the running process of the vehicle.

[0140] The controller of the vehicle can be a VCU (Vehicle Control Unit) or an ECU (Electronic Control Unit). According to the target charging power limit, the controller controls the charging power during brake regenerative charging, so that the voltage can be well controlled during the control process, overvoltage is avoided, and the charging power changes smoothly or even stably.

[0141] The battery pack power limit estimation method of the embodiment of the application estimates the charging voltage of the maximum voltage cell, which is closer to the voltage range that can be used by the maximum voltage cell in the next moment, so that the estimation of the target charging power limit is more accurate. Meanwhile, when the estimated charging voltage of the maximum voltage cell is in the preset threshold range, the interpolation algorithm is used to calculate the target power limit in the preset threshold range, so that the power limit can be accurately and reasonably estimated, so that the voltage can be well controlled during the control process of the vehicle, overvoltage is avoided, and the charging power changes smoothly during the control process of the vehicle.

[0142] Figure 3 The structure of the battery pack power limit estimation device embodiment of the application is shown. As shown in the figure, Figure 3 The device 300 includes a first acquisition module 310, a second acquisition module 320, a first calculation module 330, a first determination module 340, and a second determination module 350.

[0143] The first acquisition module 310 is configured to acquire the actual single minimum voltage of the minimum voltage cell in the battery pack.

[0144] The second acquisition module 320 is configured to acquire the static discharge power limit of the battery pack.

[0145] The first calculation module 330 is configured to calculate the estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit based on the actual single minimum voltage.

[0146] The first determination module 340 is configured to determine whether the estimated discharge voltage is located between the discharge voltage control threshold of the minimum voltage cell and the undervoltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the undervoltage threshold.

[0147] The second determination module 350 is configured to, when the estimated discharge voltage of the minimum voltage cell is located between the discharge voltage control threshold and the undervoltage threshold of the minimum voltage cell, determine the target discharge power limit of the battery pack by a discharge interpolation algorithm based on the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the undervoltage threshold, and the minimum power limit of the vehicle.

[0148] The first output module is configured to output the target discharge power limit to a controller of the vehicle, so as to control the discharge power during operation of the vehicle.

[0149] The specific working process of the battery pack power limit estimation device in the embodiment of the application is consistent with the specific steps of the battery pack power limit estimation method in the above embodiment, and will not be repeated here.

[0150] The battery pack power limit estimation device in the embodiment of the application estimates the target discharge power limit by calculating the estimated discharge voltage of the minimum voltage cell, which is closer to the voltage range that can be used by the minimum voltage cell in the next moment, so that the estimation of the target discharge power limit is more accurate. Meanwhile, when the estimated discharge voltage is in the preset threshold range, the interpolation algorithm is used to calculate the target discharge power limit in the preset threshold range, so that the power limit can be accurately and reasonably estimated, so that the voltage of the vehicle can be well controlled to avoid under-voltage; meanwhile, the discharge power changes smoothly during vehicle control.

[0151] Figure 4 A structural schematic diagram of an embodiment of a battery pack power limit estimation device of the application is shown. As shown in the figure, the device 400 includes a third acquisition module 410, a fourth acquisition module 420, a second calculation module 430, a third determination module 440, and a fourth determination module 450. Specifically: Figure 4 The third acquisition module 410 is configured to acquire the actual single maximum voltage of the maximum voltage cell in the battery pack.

[0152] The third acquisition module 410 is configured to acquire the actual single maximum voltage of the maximum voltage cell in the battery pack.

[0153] The fourth acquisition module 420 is configured to acquire the static charging power limit of the battery pack.

[0154] The second calculation module 430 is configured to calculate the estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit based on the actual single maximum voltage.

[0155] The third determination module 440 is configured to determine whether the estimated charging voltage is located between the charging voltage control threshold and the overvoltage threshold of the maximum voltage cell; the charging voltage control threshold is less than the overvoltage threshold.

[0156] The fourth determination module 450 is configured to, when the estimated charging voltage is located between the charging voltage control threshold and the overvoltage threshold of the maximum voltage cell, determine the target charging power limit of the battery pack by a charging interpolation algorithm based on the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold, and the minimum power limit of the whole vehicle.

[0157] In one embodiment of the present application, a second output module is further included, configured to output the target charging power limit to a controller of the vehicle, so as to control the charging power during operation of the vehicle.

[0158] The specific working process of the battery pack power limit estimation device in the embodiments of the present application is consistent with the specific steps of the battery pack power limit estimation method in the above embodiments, and thus will not be repeated here.

[0159] The battery pack power limit estimation method in the embodiments of the present application calculates the estimated charging voltage of the maximum voltage cell, which is closer to the voltage range that can be used by the maximum voltage cell in the next moment, so as to make the estimation of the target charging power limit more accurate. Meanwhile, when the estimated charging voltage is in the preset threshold range, the interpolation algorithm is used to calculate the target charging power limit in the preset threshold range, so as to accurately and reasonably estimate the charging power limit, so that the vehicle can well control the voltage and avoid overvoltage; meanwhile, the charging power changes smoothly during the vehicle control process.

[0160] Figure 5 A structure diagram of the battery management system in the embodiments of the present application is shown, and the specific embodiments of the present application do not limit the specific implementation of the battery management system.

[0161] As shown in FIG. 5, the battery management system can include a processor 502, a communication interface 504, a memory 506, and a communication bus 508. Figure 5

[0162] The processor 502, the communication interface 504, and the memory 506 complete mutual communication through the communication bus 508. The communication interface 504 is configured to communicate with network elements such as clients or other servers, etc. The processor 502 is configured to execute the program 510, and specifically can execute the related steps in the above-mentioned battery pack power limit estimation method embodiments, so as to realize the control of the discharging power or the charging power during the operation of the vehicle.

[0163] Specifically, the program 510 can include program code, and the program code includes computer executable instructions.

[0164] ​The processor 502 can be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to perform the functions of the embodiments of the present application. The one or more processors of the battery management system can be the same type of processor, such as one or more CPUs; or different types of processors, such as one or more CPUs and one or more ASICs.

[0165] The memory 506 is configured to store a program 510. The memory 506 can include a high-speed RAM memory, and can also include a non-volatile memory, such as at least one disk memory.

[0166] The program 510 can be specifically called by the processor 502 to enable the battery management system to perform the following operations:

[0167] Obtain an actual minimum single cell voltage of a minimum voltage cell in the battery pack;

[0168] Obtain a static discharge power limit of the battery pack;

[0169] Calculate an estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit, according to the actual minimum single cell voltage;

[0170] Determine whether the estimated discharge voltage is between a discharge voltage control threshold of the minimum voltage cell and an under-voltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the under-voltage threshold;

[0171] When the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell, determine a target discharge power limit of the battery pack by a discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the under-voltage threshold, and a minimum power limit of the vehicle; or

[0172] Obtain an actual maximum single cell voltage of a maximum voltage cell in the battery pack;

[0173] Obtain a static charging power limit of the battery pack;

[0174] Calculate an estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit, according to the actual maximum single cell voltage;

[0175] Determine whether the estimated charging voltage is between a charging voltage control threshold of the maximum voltage cell and an over-voltage threshold of the maximum voltage cell; the charging voltage control threshold is less than the over-voltage threshold;

[0176] When the estimated charging voltage is between the charging voltage control threshold of the maximum voltage cell and the overvoltage threshold of the maximum voltage cell, a target charging power limit value of the battery pack is determined by a charging interpolation algorithm according to the estimated charging voltage, the static charging power limit value, the charging voltage control threshold, the overvoltage threshold, and a minimum power limit value of the whole vehicle.

[0177] The process of power limit value estimation of the battery management system in the embodiment of the application is consistent with the specific steps of the battery pack power limit value estimation method in the above embodiment, and will not be repeated here.

[0178] The battery management system in the embodiment of the application can calculate the estimated voltage, which is closer to the real voltage value of the battery pack, so that the estimation of the target power limit value is more accurate. At the same time, when the estimated voltage is in the preset threshold interval, the target power limit value in the preset threshold interval is calculated by using the interpolation algorithm, so that the power limit value can be accurately and reasonably estimated, so that the vehicle can well control the voltage and avoid under-voltage; at the same time, the power change in the vehicle control process is smooth.

[0179] The embodiment of the application also provides a power automobile, which comprises the battery management system in the above embodiment. The battery management system is used to perform the battery pack power limit value estimation in the above embodiment. The process of power limit value estimation of the battery management system of the power automobile is consistent with the specific steps of the battery pack power limit value estimation method in the above embodiment, and will not be repeated here.

[0180] The power automobile in the embodiment of the application can calculate the estimated voltage, which is closer to the real voltage value of the battery pack, so that the estimation of the target power limit value is more accurate. At the same time, when the estimated voltage is in the preset threshold interval, the target power limit value in the preset threshold interval is calculated by using the interpolation algorithm, so that the power limit value can be accurately and reasonably estimated, so that the vehicle can well control the voltage and avoid under-voltage; at the same time, the power change in the vehicle control process is smooth.

[0181] The embodiment of the application provides a computer readable storage medium, which stores at least one executable instruction. The executable instruction, when running on a battery pack power limit value estimation device, causes the battery pack power limit value estimation device to perform the battery pack power limit value estimation method in any method embodiment.

[0182] The executable instruction can be specifically used to cause the battery pack power limit value estimation device to perform the following operations:

[0183] The actual minimum single cell voltage of the minimum voltage cell in the battery pack is obtained;

[0184] obtaining a static discharge power limit of the battery pack;

[0185] calculating an estimated discharge voltage of the minimum voltage cell of the battery pack when the battery pack is discharged according to the static discharge power limit, according to the actual single cell minimum voltage;

[0186] determining whether the estimated discharge voltage is between a discharge voltage control threshold of the minimum voltage cell and an under-voltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the under-voltage threshold;

[0187] when the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the under-voltage threshold of the minimum voltage cell, determining a target discharge power limit of the battery pack by a discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the under-voltage threshold, and a minimum power limit of the whole vehicle; or

[0188] obtaining an actual single cell maximum voltage of a maximum voltage cell in the battery pack;

[0189] obtaining a static charge power limit of the battery pack;

[0190] calculating an estimated charge voltage of the maximum voltage cell of the battery pack when the battery pack is charged according to the static charge power limit, according to the actual single cell maximum voltage;

[0191] determining whether the estimated charge voltage is between a charge voltage control threshold of the maximum voltage cell and an over-voltage threshold of the maximum voltage cell; the charge voltage control threshold is less than the over-voltage threshold;

[0192] when the estimated charge voltage is between the charge voltage control threshold of the maximum voltage cell and the over-voltage threshold of the maximum voltage cell, determining a target charge power limit of the battery pack by a charge interpolation algorithm according to the estimated charge voltage, the static charge power limit, the charge voltage control threshold, the over-voltage threshold, and the minimum power limit of the whole vehicle.

[0193] The embodiment of the application provides a battery pack power limit estimation device for executing the battery pack power limit estimation method.

[0194] The embodiment of the application provides a computer program, which can be called by a processor to enable the battery pack power limit estimation device to execute the battery pack power limit estimation method in any method embodiment.

[0195] The embodiment of the present application provides a computer program product, the computer program product comprises a computer program stored on a computer readable storage medium, the computer program comprises program instructions, when the program instructions run on a computer, the computer executes the estimation method of the battery pack power limit value in any method embodiment.

[0196] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other apparatus. Various general purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent from the description above. In addition, the present embodiments are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the present application as described herein, and any references below to specific languages are provided for disclosure of enablement only.

[0197] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application can be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been described in detail in order to avoid obscuring the understanding of this description.

[0198] Similarly, it is to be understood that the above description is only illustrative of the application and certain examples thereof, and is subject to the prior art. Numerous modifications and changes can be devised by those skilled in the art without departing from the true spirit of the application. The descriptions in connection with the various examples are intended to be illustrative only and are not intended to be limiting to the scope of the application, as defined by the appended claims.

[0199] Those of skill in the art would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0200] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of elements or steps other than those listed in a claim. The word 'a' or 'an' preceding an element does not exclude the presence of a plurality of such elements. The application can be implemented by means of both hardware and software, and any combination thereof. In a unitary claim, several devices, apparatuses or means can be listed, comprising means for carrying out a certain task. The use of the term'means' in a claim is intended to refer to a combination of devices, apparatuses or means for carrying out a task. The word 'first','second', 'third', etc. do not imply any order. The use of these terms is to be construed as names. The steps of any of the methods recited herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step.

Claims

1. A method for estimating a battery pack power limit, characterized in that: The method comprises: Obtaining the actual minimum voltage of a cell with the minimum voltage in the battery pack, where the actual minimum voltage of the cell with the minimum voltage is the voltage value corresponding to the cell with the minimum actual voltage in the battery pack; Obtaining a static discharge power limit value of the battery pack; Calculating, based on the actual single cell minimum voltage, an estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit; determining whether the estimated discharge voltage is between a discharge voltage control threshold of the minimum voltage cell and an undervoltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the undervoltage threshold; When the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the undervoltage threshold of the minimum voltage cell, the target discharge power limit of the battery pack is determined by a discharge interpolation algorithm based on the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the undervoltage threshold and the minimum power limit of the vehicle.

2. The method according to claim 1, characterized in that The obtaining of the static discharge power limit of the battery pack includes: Get the minimum state of charge value of the battery cells in the battery pack; acquiring a first temperature of the battery pack; The static discharge power limit is obtained by searching a preset first correspondence table of state of charge, temperature and discharge power according to the minimum state of charge value and the first temperature of the battery pack.

3. The method according to claim 1, characterized in that The calculating, based on the actual minimum cell voltage, the estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit, includes: Obtaining an actual single-cell minimum voltage of a minimum voltage cell in the battery pack, an actual discharge current of the minimum voltage cell, and a discharge state internal resistance corresponding to the minimum voltage cell; determining a discharge current limit of the battery pack according to the static discharge power limit; The estimated discharge voltage of the minimum voltage cell is determined according to the actual minimum voltage of the minimum voltage cell, the actual discharge current of the minimum voltage cell, the discharge current limit of the battery pack, and the internal resistance of the minimum voltage cell in the discharge state.

4. The method according to any one of claims 1 to 3, characterized in that When the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage cell and the undervoltage threshold of the minimum voltage cell, determining the target discharge power limit of the battery pack by a discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the undervoltage threshold, and the minimum power limit of the vehicle, includes: The difference between the estimated discharge voltage and the undervoltage threshold of the minimum voltage cell is used as an input difference term of the PID algorithm to obtain a discharge correction term; modifying the discharge interpolation algorithm according to the discharge correction term; The target discharge power limit of the battery pack is calculated using a modified discharge interpolation algorithm according to the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the undervoltage threshold, and the minimum power limit of the vehicle.

5. The method according to claim 4, characterized in that The modified discharge interpolation algorithm is: ； in, represents a target discharge power limit of the battery pack; Indicates the static discharge power limit of the battery pack; Indicates the minimum power limit of the vehicle; is the discharge voltage control threshold of the minimum voltage battery cell; is the undervoltage threshold of the minimum voltage cell; represents a discharge correction term calculated based on the estimated discharge voltage and the undervoltage threshold.

6. A method for estimating a battery pack power limit, characterized in that: The method comprises: Obtaining the actual maximum voltage of a cell with the maximum voltage in the battery pack, where the actual maximum voltage of the cell with the maximum voltage is the voltage value corresponding to the cell with the maximum actual voltage in the battery pack; Obtaining a static charging power limit of the battery pack; Calculating, based on the actual maximum cell voltage, an estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit; determining whether the estimated charging voltage is between a charging voltage control threshold of the maximum voltage battery cell and an overvoltage threshold of the maximum voltage battery cell; the charging voltage control threshold is less than the overvoltage threshold; When the estimated charging voltage is between the charging voltage control threshold of the maximum voltage battery cell and the overvoltage threshold of the maximum voltage battery cell, the target charging power limit of the battery pack is determined by a charging interpolation algorithm based on the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold and the minimum power limit of the vehicle.

7. The method according to claim 6, characterized in that The obtaining of the static charging power limit of the battery pack includes: Obtaining a maximum state of charge value of a battery cell in a battery pack and a second temperature of the battery pack; The static charging power limit is obtained by searching a preset second correspondence table of state of charge, temperature and charging power according to the maximum state of charge value and the second temperature of the battery pack.

8. The method according to claim 6, characterized in that The calculating, based on the actual maximum cell voltage, an estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit, includes: Obtaining the actual maximum single cell voltage of the battery cell in the battery pack, the actual charging current of the maximum voltage battery cell, and the corresponding charging state internal resistance of the maximum voltage battery cell; determining a charging current limit of the battery pack according to a static charging power limit of the battery pack; The estimated charging voltage is determined according to the actual maximum cell voltage, the actual charging current, the charging current limit, and the charging state internal resistance.

9. The method according to any one of claims 6 to 8, characterized in that: When the estimated charging voltage is between the charging voltage control threshold of the maximum voltage cell and the overvoltage threshold of the maximum voltage cell, determining the target charging power limit of the battery pack by a charging interpolation algorithm according to the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold, and the minimum power limit of the vehicle, includes: Using the difference between the estimated charging voltage and the overvoltage threshold of the maximum voltage battery cell as an input difference term of the PID algorithm to obtain a charging correction term; modifying the charging interpolation algorithm according to the charging correction term; A target charging power limit of the battery pack is calculated using a modified charging interpolation algorithm based on the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold, and the minimum power limit of the vehicle.

10. The method according to claim 9, characterized in that The modified charging interpolation algorithm is: ； in, represents a target charging power limit of the battery pack; Indicates the static charging power limit of the battery pack; Indicates the minimum power limit of the vehicle; is the charging voltage control threshold of the maximum voltage battery cell; is the overvoltage threshold of the maximum voltage battery cell; represents a charging correction term calculated based on the estimated charging voltage and the overvoltage threshold.

11. A device for estimating a battery pack power limit, characterized in that: The device comprises: A first acquisition module is configured to acquire an actual minimum voltage of a cell with a minimum voltage in a battery pack, where the actual minimum voltage of the cell with the minimum voltage is a voltage value corresponding to a cell with the minimum actual voltage in the battery pack; A second acquisition module is used to obtain a static discharge power limit of the battery pack; A first calculation module is configured to calculate, based on the actual minimum cell voltage, an estimated discharge voltage of the minimum voltage cell when the battery pack is discharged according to the static discharge power limit; A first determination module is configured to determine whether the estimated discharge voltage is between a discharge voltage control threshold of the minimum voltage cell and an undervoltage threshold of the minimum voltage cell; the discharge voltage control threshold is greater than the undervoltage threshold; The second determination module is used to determine the target discharge power limit of the battery pack through a discharge interpolation algorithm based on the estimated discharge voltage, the static discharge power limit, the discharge voltage control threshold, the undervoltage threshold and the minimum power limit of the vehicle when the estimated discharge voltage is between the discharge voltage control threshold of the minimum voltage battery cell and the undervoltage threshold of the minimum voltage battery cell.

12. A device for estimating a battery pack power limit, characterized in that: The device comprises: A third acquisition module is used to obtain the actual maximum voltage of the maximum voltage cell in the battery pack, where the actual maximum voltage of the maximum voltage cell is the voltage value corresponding to the cell with the maximum actual voltage in the battery pack; a fourth acquisition module, configured to acquire a static charging power limit of the battery pack; a second calculation module, configured to calculate, based on the actual maximum cell voltage, an estimated charging voltage of the maximum voltage cell when the battery pack is charged according to the static charging power limit; a third determining module, configured to determine whether the estimated charging voltage is between a charging voltage control threshold of the maximum voltage battery cell and an overvoltage threshold of the maximum voltage battery cell; and the charging voltage control threshold is less than the overvoltage threshold; The fourth determination module is used to determine the target charging power limit of the battery pack through a charging interpolation algorithm based on the estimated charging voltage, the static charging power limit, the charging voltage control threshold, the overvoltage threshold and the minimum power limit of the vehicle when the estimated charging voltage is between the charging voltage control threshold of the maximum voltage battery cell and the overvoltage threshold of the maximum voltage battery cell.

13. A battery management system, characterized in that: include: A processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform the operation of the battery pack power limit estimation method according to any one of claims 1 to 10.

14. A powered vehicle, characterized in that: The electric vehicle includes the battery management system as claimed in claim 13.

15. A computer-readable storage medium, characterized in that The computer-readable storage medium stores at least one executable instruction, which, when executed on the battery power limit estimation device, enables the battery power limit estimation device to perform the battery power limit estimation method according to any one of claims 1 to 10.

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