A control method and device of a battery system, a vehicle and a medium

Abstract

This application discloses a control method, apparatus, vehicle, and medium for a battery system. The battery system includes multiple battery packs connected in series. The method includes: acquiring the effective state of charge (SOC) of the battery packs; determining the operating conditions of the battery system based on the SOC; the operating conditions include charging and discharging conditions. In the charging condition, the charging current path of the battery packs is adjusted according to the SOC to regulate the charging process and reduce the SOC difference between the battery packs in the charging end region. In the discharging condition, the discharging output state of the battery packs is adjusted according to the SOC to suppress the increase of SOC difference between the battery packs. Therefore, by differentially controlling the charging and discharging states of the series-connected battery packs, the SOC difference between the packs is reduced and suppressed, thereby improving the energy utilization and charging / discharging performance of the battery system.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a control method, device, vehicle, and medium for a battery system. Background Technology

[0002] With the development of power battery systems for new energy vehicles, a battery architecture in which multiple battery packs are connected in series can be adopted to improve the system's power supply capacity and reliability. In the series connection state, the charging and discharging current of each battery pack is consistent. However, due to factors such as battery capacity, aging degree, temperature, and usage conditions, there may be differences in the state of charge between different battery packs.

[0003] Currently, passive balancing methods are mainly used for cell-level balancing, and are difficult to effectively adjust the differences in state of charge (SOC) between battery packs. During charging, battery packs with higher SOC reach their charging limit first, which limits the continued charging of the series system, making it difficult for battery packs with lower SOC to replenish energy. In addition, during cycle use, the differences in SOC between packs may continue to accumulate, thereby affecting the usable capacity and charge / discharge performance of the battery system.

[0004] Therefore, how to improve the charging and discharging performance and reliability of battery systems is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, one aspect of this application provides a control method for a battery system, the battery system comprising a plurality of battery packs connected in series; the method comprising: Obtain the effective state of charge of the battery pack; The operating conditions of the battery system are determined based on the effective state of charge; the operating conditions include charging conditions and discharging conditions. In the charging condition, the charging current path of the battery pack is adjusted according to the effective state of charge in order to regulate the charging process of the battery pack and reduce the difference in the state of charge of the battery pack in the charging end region. During the discharge operation, the discharge output state of the battery pack is adjusted according to the effective state of charge to suppress the increase of the difference in state of charge between the battery packs.

[0006] Optionally, the battery system includes a battery control unit, which includes a main controller and at least one slave controller; the battery control unit is electrically connected to the battery pack. The step of obtaining the effective state of charge of the battery pack includes: Obtain the battery status data of the battery pack; The main controller determines the first state of charge estimate of each battery pack based on the battery state data. The at least one slave controller determines a second state-of-charge estimate for each of the battery packs based on the battery state data. The effective state of charge is determined based on the first state of charge estimate and the second state of charge estimate.

[0007] Optionally, determining the effective state of charge based on the first state of charge estimate and the second state of charge estimate includes: For the same battery pack, determine the charge difference between the first state of charge estimate and the second state of charge estimate; Determine whether the charge difference is less than a preset difference; If it is less than, the first state of charge estimate and the second state of charge estimate are fused to obtain the effective state of charge; If it is not less than, proceed with the following steps: A deviation check is performed on the first state of charge estimate and the second state of charge estimate to determine the source of the deviation that causes the difference in charge. If the source of deviation is determined, the estimated state of charge corresponding to the source of deviation is corrected, and the effective state of charge is determined based on the corrected estimated state of charge. If the source of deviation is not determined, the lower of the first state of charge estimate and the second state of charge estimate is determined as the effective state of charge.

[0008] Optionally, the main controller determines the first state of charge estimate using a filtering estimation algorithm; The at least one slave controller determines the second state of charge estimate using an open-circuit voltage lookup table algorithm and an ampere-hour integration algorithm.

[0009] Optionally, adjusting the charging current path of the battery pack according to the effective state of charge during the charging condition includes: If the effective state of charge of each of the battery packs has not reached the charging end threshold, control the battery packs to be charged in series. If the state of charge of at least one target battery pack reaches the charging end threshold and the state of charge of at least one other battery pack does not reach the charging end threshold, the charging current path of the target battery pack is adjusted to suspend the charging of the target battery pack, while the other battery packs continue to charge. When the effective state of charge of each battery pack reaches the charging end threshold, each battery pack is controlled to perform constant voltage charging; the charging current corresponding to the constant voltage charging is less than the charging current when none of the battery packs have reached the charging end threshold.

[0010] Optionally, each of the battery packs is connected to a corresponding switching assembly, and the charging current path includes a series charging path and a bypass charging path; When the switching assembly is controlled to activate the series charging path, the series charging path passes through the corresponding battery pack. When the switching assembly is controlled to activate the bypass charging path, the bypass charging path bypasses the corresponding battery pack. Correspondingly, adjusting the charging current path of the target battery pack includes: Control the switching component corresponding to the target battery pack to activate the bypass charging path corresponding to the target battery pack.

[0011] Optionally, if the effective state of charge of each of the battery packs has not reached the charging end threshold, control the battery packs to be charged in series, including: Determine the charging request current corresponding to each of the battery packs; The target charging request current of the battery system is determined based on the minimum value among the plurality of the charging request currents; Each of the battery packs is charged in series according to the target charging request current.

[0012] Optionally, adjusting the discharge output state of the battery pack according to the effective state of charge during the discharge condition includes: If the effective state of charge of at least one target battery pack is less than the lower discharge threshold, and the effective state of charge of at least one other battery pack is not less than the lower discharge threshold, the target battery pack is controlled to stop outputting electrical energy, and at least one of the other battery packs is controlled to continue outputting electrical energy.

[0013] Optionally, the control method for the battery system further includes: Obtain the state-affecting parameters of the battery pack; the state-affecting parameters include at least one of the following: the difference in state of charge between the battery packs, the difference in battery temperature, the difference in battery health status, and the discharge rate; Based on the state influence parameters, the preset baseline discharge lower limit threshold is adjusted to obtain the discharge lower limit threshold. The lower discharge limit threshold is positively correlated with the state of charge difference and the discharge rate, and negatively correlated with the battery temperature difference and the battery health state difference.

[0014] Optionally, the operating condition further includes a fault condition; in the fault condition, the method further includes: Determine the fault type of the battery system; When the fault type is a controller fault, the faulty controller is determined from the main controller and the at least one slave controller, and any controller other than the faulty controller is controlled to take over the control function corresponding to the faulty controller; When the fault type is a battery pack fault, the faulty battery pack is identified from the plurality of battery packs, the faulty battery pack is controlled to stop the charging process, and at least one normal battery pack is controlled to supply power to the load, and the output power of the battery system is controlled not to exceed the first power. When the fault type is that both the controller and the battery pack fail simultaneously, at least one normal controller is controlled to supply power to at least one normal battery pack, and the output power of the battery system is controlled not to exceed the second power, so that the vehicle decelerates and stops; wherein, the second power is less than the first power.

[0015] Another aspect of this application provides a control device for a battery system, the battery system comprising a plurality of battery packs connected in series; the device includes: A state of charge acquisition module is used to acquire the effective state of charge of the battery pack; The operating condition determination module is used to determine the operating condition of the battery system based on the effective state of charge; the operating condition includes charging condition and discharging condition. The charging path control module is used to adjust the charging current path of the battery pack according to the effective state of charge during the charging operation, so as to regulate the charging process of the battery pack and reduce the state of charge difference of the battery pack in the charging end region. The discharge output control module is used to adjust the discharge output state of the battery pack according to the effective state of charge during the discharge operation, so as to suppress the increase of the difference in state of charge between the battery packs.

[0016] Another aspect of this application provides a vehicle including a battery system, a memory, and a processor; the battery system includes a plurality of battery packs connected in series; the battery system is connected to the processor. The memory stores a computer program that can run on the processor, and when the processor executes the computer program, it implements the steps of the control method for the battery system.

[0017] Another aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the control method for the battery system.

[0018] The battery system control method, apparatus, vehicle, and medium provided in this application have the following beneficial effects: By acquiring the effective state of charge (SOC) of multiple series-connected battery packs and controlling them separately for charging and discharging conditions, the charging process of different battery packs is adjusted during charging by regulating the charging current path of each battery pack, thereby reducing the difference in SOC between the packs at the end of charging. During discharging, the discharging output state of each battery pack is adjusted to suppress further increases in the difference in SOC between the packs. This improves the consistency of SOC among the series-connected battery packs, reduces the limitation of low SOC battery packs on the system's usable capacity, and thus improves the energy utilization rate and charge / discharge performance of the battery system. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a control method for a battery system provided in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of a battery system provided in an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of a battery system provided in another embodiment of this application.

[0022] Figure 4 This is a schematic diagram illustrating the principle of a control method for a battery system provided in an embodiment of this application.

[0023] Figure 5 This is a timing diagram illustrating a control method for a battery system provided in an embodiment of this application.

[0024] Figure 6 This is a schematic diagram of a battery system provided in another embodiment of this application.

[0025] Figure 7 This is a schematic diagram illustrating the principle of a control method for a battery system under fault conditions provided in an embodiment of this application.

[0026] Figure 8 This is a schematic diagram of the structure of a control device for a battery system provided in an embodiment of this application.

[0027] Figure 9 This is a structural schematic diagram of a vehicle provided in an embodiment of this application.

[0028] The attached diagram is labeled as follows: 20 is the battery control unit, 21 is the battery pack, 22 is the high-voltage bus, 23 is the motor inverter, 24 is the switching assembly, 200 is the main controller, 201 is the slave controller, 80 is the state of charge acquisition module, 81 is the operating condition determination module, 82 is the charging path control module, 83 is the discharge output control module, 84 is the lower limit threshold adjustment module, 85 is the fault handling module, 90 is the memory, 91 is the processor, 92 is the display screen, 93 is the input / output interface, 94 is the communication interface, 95 is the power supply, 96 is the communication bus, 97 is the battery system, 901 is the computer program, 902 is the operating system, and 903 is the data. Detailed Implementation

[0029] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0030] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0031] The Battery Management System (BMS) of new energy vehicles is a core safety component of the vehicle's three-electric system. The traditional centralized architecture of a single battery pack and a single Micro Controller Unit (MCU) can perform state-of-charge estimation, state monitoring, charge / discharge control, and protection strategies under normal operating conditions. However, when the core control unit fails or the battery pack experiences serious faults such as thermal runaway, insulation failure, or critical sensor malfunction, it typically triggers the vehicle's power-off protection, causing the vehicle to suddenly lose power while driving. Especially in high-speed driving, assisted driving, or complex road conditions, sudden power loss can lead to rear-end collisions or loss of control. On the other hand, while series-connected dual battery packs can create physical redundancy, their charging and discharging currents are forced to be identical. Traditional passive balancing is mainly applicable to cell-level deviations and cannot address ampere-hour-level state-of-charge deviations between battery packs.

[0032] To address the aforementioned technical problems, this application provides a control method, apparatus, vehicle, and medium for a battery system. First, it should be noted that the method provided in this application can be applied to a battery system comprising multiple battery packs connected in series. For ease of explanation, the following description uses battery pack A and battery pack B connected in series as an example; however, it is understood that the number of battery packs can also be three or more, and this application does not limit this. The battery system can be installed in a vehicle, which can be a pure electric vehicle, a plug-in hybrid electric vehicle, a range-extended electric vehicle, or other new energy vehicles requiring power from a high-voltage battery system; this application also does not limit this.

[0033] Figure 1 This is a flowchart illustrating a control method for a battery system provided in an embodiment of this application, as shown below. Figure 1 As shown, the method includes: S10: Obtain the effective state of charge of the battery pack; In a specific embodiment, the State of Charge (SOC) is used to characterize the ratio of the remaining available capacity of the battery pack to its rated capacity or current available capacity. The effective SOC characterizes the current actual SOC of the corresponding battery pack that can participate in charging or discharging control. During the use and charging of the battery pack, the effective SOC of the battery pack can be collected in real time [Chen Qinqin (Duoduo Chen) 2] to determine the current operating condition of the battery system.

[0034] Figure 2 This is a schematic diagram of a battery system provided as an embodiment of this application. In an optional embodiment, such as... Figure 2 As shown, the battery system may include a battery control unit 20, multiple battery packs 21 connected in series, a high-voltage bus, and a motor inverter 23. The battery control unit 20 may be a vehicle controller, a domain controller, or a microcontroller unit (MCU), and this application does not limit its application to this. Furthermore, it should be noted that in one optional embodiment, each battery pack 21 may include a cell module, a battery management unit (BMU), and necessary current, voltage, and temperature acquisition components. For ease of understanding, the following will be combined with... Figure 2 Please provide an explanation.

[0035] In some embodiments, each battery pack 21 may be configured with a battery management unit for collecting battery operating parameters. The battery control unit 20 can obtain the SOC information corresponding to each battery pack 21 and process the SOC information according to the current operating parameters of each battery pack 21 to obtain the effective SOC of each battery pack 21.

[0036] The operating parameters may include at least one of the following: voltage, current, temperature, cell voltage, available capacity, and state of health of the battery pack 21. In one optional embodiment, the SOC detection value that meets the preset valid conditions can be directly determined as the valid SOC. In another optional embodiment, the SOC detection value can be corrected based on parameters such as the current available capacity of the battery pack 21, operating temperature, or SOC estimation error, so as to reduce the SOC characterization deviation caused by capacity decay, temperature differences, or estimation errors in different battery packs 21. This application does not limit the method for obtaining the valid SOC of the battery pack 21.

[0037] S11: Determine the operating conditions of the battery system based on the effective state of charge; the operating conditions include charging conditions and discharging conditions. After obtaining the effective SOC of each battery pack 21, the current operating condition of the battery system can be determined based on the effective SOC. Specifically, the operating stage of the battery system can be identified by combining the effective SOC of each battery pack 21 with the current charge / discharge state of the battery system. When the battery system receives electrical energy from an external charging device, and the effective SOC of each battery pack 21 is within the allowable charging SOC range, it can be determined that the battery system is in a charging condition.

[0038] When the battery system outputs electrical energy to the vehicle load or other electrical load, and at least a portion of the battery pack 21 has an effective SOC within the allowable discharge range, the battery system can be determined to be in a discharge condition. Furthermore, in an optional embodiment, the corresponding charging control stage or discharging control stage can be further determined based on the effective SOC differences among the multiple battery packs 21, so as to adopt appropriate control strategies for different SOC distributions.

[0039] S12: During charging, the charging current path of the battery pack is adjusted according to the effective state of charge in order to regulate the charging process of the battery pack and reduce the difference in the state of charge of the battery pack in the end area of ​​charging. During charging, the SOC relationship between the battery packs 21 can be determined based on their effective SOC, and the charging current path for at least some of the battery packs 21 can be adjusted accordingly. Specifically, the effective SOC of the multiple battery packs 21 can be compared to identify the battery packs 21 with relatively higher and lower effective SOCs. When the effective SOC difference between the battery packs 21 is small, or when none of the battery packs 21 have entered the charging end region, the multiple battery packs 21 can be connected in series for charging, allowing the charging current to flow sequentially through each battery pack 21.

[0040] When the effective SOC of at least one battery pack 21 reaches or approaches the preset charging SOC threshold first, while the effective SOC of at least one other battery pack 21 is still lower than the preset charging SOC threshold, the battery pack 21 with a higher effective SOC can be identified as the target battery pack 21, and the charging current path corresponding to the target battery pack 21 can be adjusted to reduce or stop the charging current flowing through the target battery pack 21, while allowing the charging current to continue flowing through the other battery packs 21 with lower effective SOC.

[0041] Therefore, the effective charging duration of different battery packs 21 during the charging process can be changed, so that the battery pack 21 with a lower SOC continues to replenish its power, while the battery pack 21 with a higher SOC reduces or stops continuing to charge, thereby adjusting the charging process of each of the multiple battery packs 21.

[0042] Furthermore, in an optional embodiment, as the charging process continues, the effective SOC of each battery pack 21 can be continuously or periodically acquired, and the charging current path corresponding to each battery pack 21 can be dynamically adjusted according to the updated effective SOC. When the battery pack 21 with the original lower effective SOC gradually approaches the battery pack 21 with the higher effective SOC, the target battery pack 21 that needs to have its charging current path adjusted can be re-determined, or the normal charging state of some battery packs 21 can be restored.

[0043] It should be noted that the charging end region can be the charging stage from when at least one battery pack 21 reaches a preset end SOC threshold until the battery system meets the charging cutoff condition. By differentiating the charging current paths of different battery packs 21 in the charging end region, it is possible to prevent the battery pack 21 with a higher effective SOC from reaching its charging limit first and restricting the continued charging of the entire series battery system, thus allowing the battery pack 21 with a lower effective SOC to have the opportunity to receive further charging, thereby reducing the SOC difference among multiple battery packs 21 at the end of charging.

[0044] S13: During discharge operation, adjust the discharge output state of the battery pack according to the effective state of charge to suppress the increase of the difference in state of charge between battery packs.

[0045] During discharge operation, the discharge capacity of each battery pack 21 can be determined based on its effective SOC, and the discharge output state of at least some battery packs 21 can be adjusted accordingly. Specifically, the relationship between the effective SOC of each battery pack 21 and a preset discharge SOC threshold can be compared. When the effective SOC of each battery pack 21 is higher than the preset discharge SOC threshold, the multiple battery packs 21 can be controlled to supply power to the load in a normal discharge state.

[0046] When the effective SOC of at least one battery pack 21 drops to a preset discharge SOC threshold, while the effective SOC of at least one other battery pack 21 is still higher than the preset discharge SOC threshold, the battery pack 21 with the lower effective SOC can be identified as the target battery pack 21, and the discharge output state of the target battery pack 21 can be adjusted to reduce the extent to which the target battery pack 21 continues to output power. At the same time, other battery packs 21 with relatively higher effective SOC can be used to undertake at least part of the load power supply demand.

[0047] Adjusting the discharge output state of the target battery pack 21 can include at least one of reducing the output power of the target battery pack 21, limiting the output current of the target battery pack 21, or stopping the output of electrical energy from the target battery pack 21. By reducing the discharge level of the battery pack 21 with a low effective SOC, the rate of SOC decline of the battery pack 21 can be slowed down, preventing it from being further over-discharged relative to other battery packs 21.

[0048] When other battery packs 21 continue to output power to the load, the SOC difference between different battery packs 21 can be kept within a preset range or the growth rate of the SOC difference can be reduced, thereby suppressing the further increase of the SOC difference between series battery packs 21 during continuous discharge, and reducing the possibility that a single low SOC battery pack 21 will reach the discharge limit in advance and limit the available capacity of the entire battery system.

[0049] Therefore, the battery system control method provided in this application obtains the effective state of charge (SOC) of multiple series-connected battery packs 21 and controls them separately for charging and discharging conditions. During charging, the charging current path of each battery pack 21 is adjusted to regulate the charging process of different battery packs 21, thereby reducing the difference in SOC between packs at the end of charging. During discharging, the discharging output state of each battery pack 21 is adjusted to suppress further increase in the difference in SOC between packs. This improves the consistency of SOC among the series-connected battery packs 21, reduces the limitation of low-SOC battery packs 21 on the available capacity of the system, and thus improves the energy utilization and charge / discharge performance of the battery system.

[0050] Figure 3 The present invention provides a schematic diagram of the structure of a battery system according to another embodiment of the present application. In an optional embodiment, the battery system includes a battery control unit 20, which includes a main controller 200 and at least one slave controller 201; the battery control unit 20 is electrically connected to the battery pack. Obtain the effective state of charge of the battery pack, including: Obtain battery status data from the battery pack; The main controller determines the estimated first state of charge of each battery pack based on the battery status data. The second state of charge estimate for each battery pack is determined by at least one controller based on battery state data. The effective state of charge is determined based on the first state of charge estimate and the second state of charge estimate.

[0051] In some embodiments, such as Figure 3 As shown, the battery system includes a battery control unit 20 and multiple battery packs 21 connected in series. For ease of understanding, Figure 3 The following explanation uses two battery packs, battery pack A and battery pack B, as examples. The battery control unit 20 includes a master MCU 200 and at least one slave MCU 201. A communication connection is established between the master MCU 200 and the slave MCU 201 to realize data exchange and cross-validation of SOC estimation results.

[0052] In the physical layer, battery pack A and battery pack B are connected in series and connected to high-voltage bus 22. High-voltage bus 22 is further connected to motor inverter 23 to provide power to motor inverter 23. Battery pack A is equipped with contactor group A and bypass switch A, and battery pack B is equipped with contactor group B and bypass switch B. Battery control unit 20 can send control signals to contactor group A, bypass switch A, contactor group B, and bypass switch B to adjust the charging current path or discharge output state corresponding to different battery packs.

[0053] When determining the effective SOC of each battery pack 21, the battery status data of battery pack A and battery pack B can be acquired first. The battery status data may include at least one of the following: battery pack voltage, battery pack current, cell voltage, battery temperature, historical charge / discharge data, battery capacity, and battery health status. The battery status data can be acquired by the corresponding battery status acquisition circuit or battery management module for each battery pack and transmitted to the battery control unit 20. Figure 3 The diagram primarily illustrates the control relationship between the battery control unit 20 and the physical layer execution components. The detection circuitry used to collect battery state data can be configured according to the actual battery system structure. Figure 3 Not shown separately. In an optional embodiment, to improve the accuracy of subsequent SOC estimation, the acquired battery state data can also be filtered, outlier data removed, sampling time aligned, or data integrity verified.

[0054] After acquiring battery status data, the main MCU 200 calculates the first SOC estimate for battery pack A and battery pack B based on the battery status data. Specifically, the main MCU 200 can estimate the current remaining capacity of each battery pack based on ampere-hour integration, voltage-SOC mapping relationship, equivalent circuit model, state estimation algorithm, or a combination of multiple SOC estimation methods.

[0055] For example, the main MCU 200 can calculate the SOC change based on the previous SOC and the current charging / discharging current, and then correct the calculation results by combining the battery voltage, temperature, and available capacity, thereby obtaining the first SOC estimate for each battery pack. For multiple battery packs 21, SOC estimation can be performed separately to obtain the first SOC estimate result corresponding to each battery pack.

[0056] The slave MCU 201 can independently determine the second SOC estimate for each battery pack 21 based on the same battery state data. In one optional embodiment, the slave MCU 201 can use the same SOC estimation algorithm as the master MCU 200, but execute the calculation process independently, thereby forming independent SOC estimation results. In another optional embodiment, the slave MCU 201 can use a different SOC estimation algorithm, model parameters, or data processing method than the master MCU 200 to reduce the possibility that the same algorithm error will affect the two SOC estimation results simultaneously. When multiple slave MCUs are provided, each slave MCU can correspond to one or more battery packs, or multiple slave MCUs can calculate the second SOC estimate for the same battery pack separately; this application does not limit this.

[0057] Furthermore, the effective SOC is determined based on the first SOC estimate and the second SOC estimate. Specifically, the effective SOC of the corresponding battery pack can be determined by averaging the first SOC estimate and the second SOC estimate for the same battery pack. Of course, in some optional embodiments, the effective SOC of the corresponding battery pack can also be determined by cross-validating the first SOC estimate and the second SOC estimate for the same battery pack; this application does not limit this approach.

[0058] Figure 4 This is a schematic diagram illustrating the principle of a battery system control method provided in an embodiment of this application. In one optional embodiment, determining the effective state of charge (SOC) based on a first SOC estimate and a second SOC estimate includes: For the same battery pack, determine the charge difference between the first state-of-charge estimate and the second state-of-charge estimate; Determine whether the charge difference is less than the preset difference; If it is less than the first state of charge estimate and the second state of charge estimate, the effective state of charge is obtained by merging them. If it is not less than, proceed with the following steps: The first and second state of charge estimates are checked for deviation to determine the source of the deviation that causes the difference in charge. If the source of deviation is identified, the estimated state of charge corresponding to the source of deviation is corrected, and the effective state of charge is determined based on the corrected estimated state of charge. If the source of deviation is not determined, the lower of the first state of charge estimate and the second state of charge estimate is determined as the effective state of charge.

[0059] In some embodiments, such as Figure 4 As shown, after the main MCU determines the first SOC estimate of each battery pack and the slave MCU determines the second SOC estimate of each battery pack, the two SOC estimates can be cross-validated for the same battery pack to determine the effective SOC that ultimately participates in the charge and discharge control of the battery system.

[0060] Specifically, for any battery pack, the absolute value of the difference between the first SOC estimate and the second SOC estimate can be calculated, and this absolute value can be used as the SOC difference for the corresponding battery pack. Further, the SOC difference is compared with a preset difference to determine whether the SOC estimation results obtained by the master MCU and the slave MCU for the current battery pack are consistent. The preset difference can be pre-set based on the accuracy of the SOC estimation algorithm, the accuracy of the battery system control, and the allowable SOC estimation error. For example, Figure 4 The following example uses 3% as the preset difference value for illustration.

[0061] When the SOC difference is less than a preset difference, it can be considered that there is no significant deviation between the first and second SOC estimates, and the SOC estimation results of the master MCU and slave MCU are within the allowable error range. In this case, the first and second SOC estimates can be fused normally, and the fusion result can be determined as the effective SOC. For example, the first and second SOC estimates can be weighted according to preset weights to obtain the effective SOC. In one optional embodiment, the first and second SOC estimates can use the same weight. In another optional embodiment, different fusion weights can be determined based on the estimation accuracy of the corresponding SOC estimation algorithms of the master and slave MCUs, the current data quality, or historical estimation errors, so that the SOC estimation result with higher reliability has a larger fusion weight. By fusing two independent SOC estimation results, the impact of instantaneous fluctuations in a single SOC estimation result on the effective SOC can be reduced.

[0062] When the SOC difference is not less than a preset difference, it can be considered that there is an abnormal deviation between the first SOC estimate and the second SOC estimate. In this case, instead of directly fusing the two SOC estimates, a deviation verification process is initiated to determine the source of the deviation causing the SOC difference. Deviation verification can be based on the input data corresponding to the master MCU and slave MCU, the algorithm's running status, and the characteristics of changes in the SOC estimation results.

[0063] For example, in one optional embodiment, the battery status data such as voltage, current, and temperature obtained from the main MCU and the slave MCU can be checked separately to ensure they are complete, do not exceed the normal data range, and that there are no communication frame drops or abnormal data updates. Furthermore, it can be determined whether the changes in the first and second SOC estimates relative to the previous SOC value conform to the SOC change trend corresponding to the current charging / discharging current. In another optional embodiment, the two SOC estimation results can be checked for reasonableness by combining the battery pack terminal voltage, historical SOC, cumulative charging / discharging amount, and the internal state of the SOC estimation algorithm, thereby determining whether the abnormal deviation mainly originates from the first or second SOC estimate.

[0064] For example, in one optional embodiment, if the first SOC estimate shows an abnormal jump relative to the historical SOC, while the second SOC estimate matches the changes in battery current and battery pack terminal voltage, the estimation path corresponding to the first SOC estimate can be identified as the source of deviation. Conversely, if the second SOC estimate shows an abnormal jump or its direction of change is inconsistent with the current charge / discharge state, while the first SOC estimate remains continuously changing, the estimation path corresponding to the second SOC estimate can be identified as the source of deviation. Furthermore, when anomalies are detected in the battery state data obtained from the main MCU or from the MCU, in the internal parameters of the SOC estimation algorithm, or in the controller's operating state, the corresponding SOC estimation result can also be identified as the SOC estimate corresponding to the source of deviation.

[0065] In some embodiments, where the source of the deviation can be determined, such as Figure 4 As shown, the SOC estimate corresponding to the deviation source can be corrected. SOC correction can be performed based on at least one of the following: the SOC estimate without deviation, the most recently verified valid SOC, the current battery pack voltage, and the current cumulative charge / discharge amount. For example, the abnormal SOC estimate can be offset by using the SOC estimate without deviation as a reference.

[0066] Furthermore, after the correction is completed, the corrected SOC estimate can be fused with another SOC estimate, and the fusion result can be used as the valid SOC. Alternatively, if the corrected SOC estimate meets the preset confidence conditions, the valid SOC can be determined directly based on the corrected SOC estimate.

[0067] In other embodiments, such as Figure 4As shown, when the source of deviation cannot be determined, i.e. there is a significant difference between the first SOC estimate and the second SOC estimate, but it is not possible to reliably determine which SOC estimate is deviating based on the current battery state data, the algorithm's running status, and historical SOC changes, a conservative strategy can be adopted to determine the lower of the first and second SOC estimates as the effective SOC.

[0068] For example, if the first estimated SOC is 45% and the second estimated SOC is 40%, and the specific reason for the difference cannot be determined, 40% can be determined as the effective SOC of the current battery pack. Using a lower SOC as the control basis can avoid the battery pack from continuing to over-discharge due to an overestimated SOC, and can provide a relatively conservative SOC basis for subsequent power limiting, charge / discharge control, or safety degradation. Figure 4 As shown, when the source of deviation cannot be identified, a corresponding conservative control strategy can be implemented based on the effective SOC, and the battery system output power can be limited or a maintenance request can be generated when necessary.

[0069] Based on the above embodiments, as an optional embodiment, the main controller determines the first state of charge estimate value through a filtering estimation algorithm; At least one controller determines the second state-of-charge estimate using an open-circuit voltage lookup table algorithm and an ampere-hour integration algorithm.

[0070] In some embodiments, Figure 4 The process of determining the first SOC estimate by the main MCU and the second SOC estimate by the slave MCU can employ different SOC estimation mechanisms to reduce the possibility that the same algorithm defects or the same calculation errors will simultaneously affect the two SOC estimation results.

[0071] The main MCU can determine the first SOC estimate for each battery pack using a filtering estimation algorithm, while the slave MCU can determine the second SOC estimate for each battery pack using an open-circuit voltage lookup table algorithm and an ampere-hour integration algorithm. This results in two independent SOC estimation results that can be cross-validated.

[0072] It should be noted that this application does not limit the filtering estimation algorithm, but can be an extended Kalman filter (EKF) or an unscented Kalman filter (UKF).

[0073] Through the above method, since the two SOC estimates employ different data processing mechanisms, when one SOC estimate deviates due to model parameter bias, cumulative integral error, or abnormal state data, the other SOC estimate result can be used as a basis for cross-validation. The first and second SOC estimates are further processed according to... Figure 4 The corresponding SOC difference judgment, normal fusion, deviation verification and conservative value selection process determines the effective SOC, thereby improving the reliability of the effective SOC when used for subsequent battery pack charge and discharge control.

[0074] Figure 5 This is a timing diagram illustrating a control method for a battery system provided in an embodiment of this application. Figure 6 This is a schematic diagram of a battery system provided in another embodiment of the present application. In one optional embodiment, during charging, the charging current path of the battery pack is adjusted according to the effective state of charge, including: When the effective state of charge of each battery pack has not reached the charging end threshold, control the battery packs to be charged in series. If the state of charge of at least one target battery pack reaches the charging end threshold and the state of charge of at least one other battery pack does not reach the charging end threshold, the charging current path of the target battery pack is adjusted to suspend the charging of the target battery pack, while the other battery packs continue to charge. When the effective state of charge of each battery pack reaches the charging end threshold, the battery pack is controlled to perform constant voltage charging; the charging current corresponding to constant voltage charging is less than the charging current when none of the battery packs have reached the charging end threshold.

[0075] In some embodiments, such as Figure 5 and Figure 6 As shown, under charging conditions, the charging process can be divided into a constant current charging stage, an equalization window stage, and a charging end stage based on the effective SOC of each battery pack 21, and different charging control methods can be adopted in different stages. Figure 5 Taking battery pack A and battery pack B as examples, the corresponding charging control timing is illustrated. The master MCU and slave MCU continuously or periodically acquire the SOC_A corresponding to battery pack A and the SOC_B corresponding to battery pack B, and determine the current charging stage and corresponding charging control strategy based on the relationship between SOC_A, SOC_B and the charging end threshold. The charging end threshold can be preset according to the battery type, charging characteristics, and allowable charging SOC range, for example... Figure 5 The example used is 90% as the end-of-charge threshold.

[0076] During the constant current charging process in Phase 1, when the effective SOC of both battery pack A and battery pack B has not reached the charging end threshold, the battery packs can be controlled to remain connected in series, and the charger will charge battery pack A and battery pack B in series according to the target charging request current. Because multiple battery packs are connected in series, the charging current flows sequentially through each battery pack, and each battery pack has the same series charging current. For example... Figure 5 As shown, a 0.5C rate can be used as the target charging request current for this stage, meaning the charger provides charging current to the series-connected battery packs A and B at a charging rate of 0.5C. During constant current charging, the master MCU and slave MCU continuously monitor SOC_A and SOC_B and determine whether any battery pack reaches the charging end threshold first.

[0077] During the equalization window process in Phase Two, when the effective SOC of at least one target battery pack reaches the charging end threshold, while the effective SOC of at least one other battery pack has not yet reached the charging end threshold, charging of the target battery pack can be paused, while the other battery packs continue to receive charge. See also Figure 5 When SOC_A reaches 90% first, while SOC_B is still below 90%, battery pack A can be identified as the target battery pack. At this time, the main MCU sends a control signal to the switching component, causing the charging current path corresponding to battery pack A to switch from a series charging path passing through battery pack A to a bypass charging path that bypasses battery pack A.

[0078] After the path switching is completed, the charging current bypasses battery pack A, causing battery pack A to pause charging. Simultaneously, the series charging path corresponding to battery pack B remains open, allowing battery pack B to continue receiving charge according to the current charging request current. For example, as... Figure 5 As shown, battery pack B continues to be charged at 0.5C. This avoids further charging of battery packs with higher SOC, while providing time for battery packs with lower SOC to replenish their charge, thus reducing the SOC difference between different battery packs at the end of the charging process.

[0079] During the equalization window phase, the effective SOC of other battery packs that have not yet reached the charging end threshold can be continuously monitored. When the SOC_B of battery pack B gradually increases and reaches 90%, it can be determined that both battery pack A and battery pack B have reached the charging end threshold, and the bypass charging control for battery pack A ends. Specifically, the bypass charging path corresponding to battery pack A can be disconnected, and a new series charging path passing through battery pack A can be established, so that battery pack A and battery pack B are once again in a connected state that can charge together, and then the charging end control in phase three begins.

[0080] like Figure 5As shown, in stage three, when the effective SOC of each battery pack reaches the charging end threshold, constant voltage charging can be controlled for each battery pack. During constant voltage charging, the target charging voltage of the battery system or the target end voltage of each battery pack can be used as the control target. As the voltage of each battery pack gradually approaches the target voltage, the charging current is reduced, so that the charging current in this stage is less than the charging current used when none of the battery packs have reached the charging end threshold. For example, Figure 5 After entering the final stage of charging, a smaller charging current of 0.1C is used, that is, charging is carried out at 0.1C during trickle charging.

[0081] During constant voltage charging, at least one of the following can be monitored: terminal voltage, charging current, and state of charge (SOC) of each battery pack. It can then be determined whether each battery pack meets the preset charging cutoff conditions. For example, when the terminal voltage of each battery pack reaches the target terminal voltage and the charging current drops to the preset cutoff current, it can be determined that the charging state of multiple battery packs has reached the cutoff condition, and a charging completion signal can be sent to the charger, causing the charger to stop outputting charging current.

[0082] Therefore, through the three stages of constant current charging, equalization window control and constant voltage charging, it is possible to provide independent charging opportunities for battery packs with lower SOC while maintaining high initial charging efficiency. Furthermore, a smaller current is used to complete the final charging after each battery pack enters the charging end, thereby reducing the SOC difference between series-connected battery packs.

[0083] In one optional embodiment, each battery pack is connected to a corresponding switching assembly, and the charging current path includes a series charging path and a bypass charging path. When the control switch assembly is turned on to conduct the series charging path, the series charging path passes through the corresponding battery pack. When the control switch assembly is activated to enable the bypass charging path, the bypass charging path bypasses the corresponding battery pack. Correspondingly, the charging current path of the target battery pack is adjusted, including: Control the switching component corresponding to the target battery pack to activate the bypass charging path corresponding to the target battery pack.

[0084] In some embodiments, such as Figure 6 As shown, each battery pack 21 is connected to a corresponding switch assembly 24. The switch assembly 24 is used to switch between a series charging path passing through the corresponding battery pack and a bypass charging path that bypasses the corresponding battery pack. Similarly, Figure 6Taking battery packs A and B connected in series as an example, each battery pack A and battery pack B is equipped with a switching assembly 24. In an optional embodiment, the switching assembly 24 can be a single-pole double-throw switch. By changing the connection relationship between the common terminal and different switching terminals in the switching assembly 24, the corresponding battery pack can be selectively connected to the series charging path or the bypass charging path. In addition to a single-pole double-throw switch, the switching assembly 24 can also be an equivalent switching circuit composed of a relay, contactor, or semiconductor switching device, which is not limited in this application.

[0085] In one optional embodiment, when the switch component 24 is in the first switching state, the series charging path of the corresponding battery pack can be turned on, allowing the charging current to flow through the corresponding battery pack. For example, when both battery pack A and battery pack B need to be charged normally, the switch component 24 corresponding to battery pack A and the switch component 24 corresponding to battery pack B can be controlled to turn on their respective series charging paths, allowing the charging current to flow through battery pack A and battery pack B in sequence.

[0086] In another alternative embodiment, when the switching component 24 is in the second switching state, the bypass charging path of the corresponding battery pack can be activated. The bypass charging path can be activated via... Figure 6 The bridging bus shown is formed so that the charging current flows from one side of the corresponding battery pack through the bridging bus to the other side of the battery pack, without flowing through the corresponding battery pack again. Therefore, without interrupting the charging circuit of the entire series battery system, charging of any single target battery pack can be paused while other battery packs continue to charge.

[0087] Below, in conjunction with Figure 5 and Figure 6 To explain, when the SOC_A of battery pack A reaches the charging end threshold first, while the SOC_B of battery pack B has not yet reached the charging end threshold, battery pack A can be identified as the target battery pack. The main MCU sends a switching control signal to the switching component 24 corresponding to battery pack A, causing the switching component 24 to switch from the switching state of conducting the series charging path to the switching state of conducting the bypass charging path. After the switch, the charging current bypasses battery pack A through the bridging bus. At the same time, the switching component 24 corresponding to battery pack B continues to maintain the series charging path conduction, allowing the charging current to continue flowing through battery pack B, enabling battery pack B to continue to replenish its charge.

[0088] When the effective SOC of battery pack B also reaches the charging end threshold, the switch component 24 corresponding to battery pack A can be controlled to exit the bypass state, and the series charging path through battery pack A can be re-connected, so that battery pack A and battery pack B return to the connected state of jointly participating in charging, and then proceed to the next step. Figure 5The constant voltage charging stage is shown. For a battery system comprising three or more battery packs connected in series, the switching components 24 corresponding to each battery pack can be controlled separately in the same manner, thereby selectively bypassing one or more target battery packs according to the order in which each battery pack reaches the charging end threshold, allowing battery packs that have not yet reached the charging end threshold to continue charging.

[0089] It should be noted that, in Figure 6 The diagram also shows components such as the positive main relay, pre-charge relay, pre-charge resistor, main negative relay, charging positive relay, and charging negative relay connected to the high-voltage circuit of the battery system. When charging begins, the corresponding relays can be used to establish a high-voltage charging circuit for the entire vehicle.

[0090] In one optional embodiment, when the effective state of charge of each battery pack has not reached the charging end threshold, controlling the battery packs to perform series charging includes: Determine the charging request current for each battery pack; The target charging request current of the battery system is determined based on the minimum value among multiple charging request currents. Each battery pack is charged in series according to the target charging request current.

[0091] In some embodiments, Figure 5 During the constant current charging process in stage one, when the effective SOC of each battery pack has not reached the charging end threshold, the current allowable charging request current for each battery pack can be determined, and the target charging request current for the entire series battery system can be determined based on the charging request currents corresponding to multiple battery packs. Since the charging current flowing through each battery pack is the same after multiple battery packs are connected in series, in order to avoid the series charging current exceeding the current allowable charging current of any battery pack, the minimum value among the multiple charging request currents can be determined as the target charging request current of the battery system.

[0092] As the charging process proceeds, the effective SOC and other battery status data of each battery pack can be periodically reacquired, and the charging request current corresponding to each battery pack and the target charging request current of the battery system can be updated, so that the series charging current adapts to the changes in the charging capacity of each battery pack.

[0093] When the effective SOC of any battery pack reaches the charging end threshold, the control state of the above-mentioned battery packs being charged in series can be exited, and then proceed according to... Figure 5 The equalization window control logic switches the target battery pack that has reached the charging end threshold to the bypass charging path, allowing other battery packs that have not yet reached the charging end threshold to continue charging.

[0094] Therefore, by using the minimum value among multiple charging request currents as the common series charging current, the different charging capabilities of each battery pack can be taken into account in the first stage, avoiding the battery pack with lower charging capability being subjected to excessive charging current in order to meet the needs of the battery pack with higher charging capability.

[0095] In one optional embodiment, during discharge operation, adjusting the discharge output state of the battery pack according to the effective state of charge includes: If the effective state of charge of at least one target battery pack is less than the lower discharge threshold, and the effective state of charge of at least one other battery pack is not less than the lower discharge threshold, the target battery pack is controlled to stop outputting electrical energy, and at least one other battery pack is controlled to continue outputting electrical energy.

[0096] In some embodiments, when the battery system is in discharge mode, the effective SOC of each battery pack can be continuously or periodically acquired, and the discharge output state of different battery packs can be controlled based on the relationship between the effective SOC of each battery pack and the discharge lower limit threshold. The discharge lower limit threshold is used to characterize the lower limit of SOC at which the battery pack is allowed to continue participating in normal discharge. When the effective SOC of a battery pack drops below the discharge lower limit threshold, it indicates that continued discharge of the battery pack may lead to a larger SOC difference relative to other battery packs, and therefore the discharge of the battery pack can be limited.

[0097] Specifically, the effective SOC of each battery pack can be compared with the corresponding lower discharge threshold. When the effective SOC of each battery pack is not less than the lower discharge threshold, each battery pack can maintain normal power output, allowing multiple series-connected battery packs to jointly meet the vehicle's power demand. When the effective SOC of at least one battery pack is less than the lower discharge threshold, while the effective SOC of at least one other battery pack is still not less than the lower discharge threshold, the battery pack with the effective SOC less than the lower discharge threshold can be identified as the target battery pack, and the target battery pack can be controlled to stop outputting power. At the same time, at least one other battery pack with an effective SOC not less than the lower discharge threshold can be controlled to continue outputting power.

[0098] For example, taking a battery system comprising battery pack A and battery pack B, during normal discharge, the effective SOC_A corresponding to battery pack A and the effective SOC_B corresponding to battery pack B can be obtained respectively. When both SOC_A and SOC_B are not less than the lower discharge threshold, battery pack A and battery pack B can be controlled to jointly output electrical energy to the vehicle load. As the discharge process continues, if SOC_A first drops below the lower discharge threshold, while SOC_B remains not less than the lower discharge threshold, then battery pack A can be identified as the target battery pack, and battery pack A can be controlled to exit the current discharge output state, while battery pack B continues to provide electrical energy to the vehicle load.

[0099] After the target battery pack stops outputting power, the effective SOC of other battery packs and the load demand of the battery system can continue to be monitored. If the remaining battery packs participating in the discharge can meet the current load power demand, the current discharge state can be maintained. If the output power of the remaining battery packs is insufficient to meet the original load power demand, power limiting or degraded operation can be implemented in conjunction with the vehicle controller to match the actual load demand with the output capacity of the currently available battery packs.

[0100] Therefore, by stopping the output of a target battery pack with a lower SOC when it reaches the discharge limit, the further decline of the SOC of that battery pack can be slowed down, while other battery packs with relatively higher SOCs continue to undertake the discharge task. This avoids the low-SOC battery packs from continuously participating in series discharge, which would further widen the SOC difference between the packs, thereby reducing the possibility that a single low-SOC battery pack will reach a deep discharge state prematurely and limit the usable capacity of the entire battery system.

[0101] Based on the above embodiments, as an optional embodiment, the battery system control method provided in this application further includes: Obtain the state-affected parameters of the battery pack; the state-affected parameters include at least one of the following: the difference in state of charge between battery packs, the difference in battery temperature, the difference in battery health status, and the discharge rate; Based on the state influence parameters, the preset baseline discharge lower limit threshold is adjusted to obtain the discharge lower limit threshold. Among them, the lower discharge limit threshold is positively correlated with the difference in state of charge and the discharge rate, while the lower discharge limit threshold is negatively correlated with the difference in battery temperature and the difference in battery health status.

[0102] In some embodiments, the lower discharge threshold corresponding to the battery pack can be dynamically determined based on the current operating state of the battery system, rather than being limited to using a fixed SOC threshold. Specifically, a baseline lower discharge threshold can be preset, and state influence parameters that can affect the actual discharge capacity of the battery pack and the discharge consistency between packs can be obtained. The baseline lower discharge threshold is adjusted according to the state influence parameters to obtain the current lower discharge threshold used to determine whether the battery pack should continue to output electrical energy. The state influence parameters may include at least one of the following: SOC difference between battery packs, battery temperature difference, battery health state difference, and discharge rate.

[0103] Table 1 is a schematic table of relevant parameters of a discharge lower limit threshold provided in the embodiments of this application. The adjustment direction and adjustment logic of each state-affected parameter can be shown in Table 1.

[0104] Table 1 is a schematic table of relevant parameters for a certain discharge lower limit threshold. Referring to Table 1, the SOC difference can be determined based on the effective SOC of multiple battery packs. For example, the difference between the maximum and minimum effective SOC of each battery pack can be defined as the SOC difference. The larger the SOC difference, the worse the consistency of remaining capacity among the multiple battery packs. In this case, the lower discharge threshold can be increased accordingly. Therefore, by increasing the lower discharge threshold as the SOC difference increases, the time that low-SOC battery packs continue to participate in discharge can be reduced, preventing low-SOC battery packs from being further "dragged" into an over-discharge state during subsequent discharge processes. That is, the lower discharge threshold can be positively correlated with the SOC difference.

[0105] In one optional embodiment, the battery temperature difference can be obtained by subtracting the average temperature of other battery packs from the current temperature of the target battery pack. When the temperature of the target battery pack is lower than that of the other battery packs, the battery temperature difference decreases accordingly. Since the usable capacity and discharge capability of the battery pack decrease at low temperatures, the discharge lower limit threshold corresponding to the target battery pack can be increased as the battery temperature difference decreases, allowing the low-temperature battery pack to exit discharge earlier, thereby reducing the adverse effects of continued deep discharge under low-temperature conditions on the battery pack.

[0106] Regarding the battery health status difference, it can be understood that as the aging degree of the target battery pack increases, its SOH decreases, thus reducing the battery health status difference corresponding to the target battery pack. Since the actual usable capacity of a battery pack with a higher degree of aging decreases, the actual remaining usable capacity corresponding to the same apparent SOC may be relatively less. Therefore, as the battery health status difference decreases, the discharge lower limit threshold corresponding to the target battery pack can be increased, allowing the battery pack with a higher degree of aging to exit the discharge process earlier.

[0107] Regarding discharge rate, as the discharge rate increases, the voltage drop of the battery pack under load typically increases accordingly, and the amount of electricity consumed per unit time also increases. Therefore, at higher discharge rates, the lower discharge limit threshold can be increased accordingly to retain more usable electricity in the battery pack and prevent the battery pack from prematurely entering the over-discharge region due to a rapid drop in terminal voltage during high-rate discharge.

[0108] Therefore, the lower discharge limit threshold can be dynamically adjusted based on the consistency of SOC, temperature, health status, and actual discharge intensity within the battery pack, thereby improving the control accuracy and reliability of the battery system.

[0109] Figure 7 This is a schematic diagram illustrating the principle of a battery system control method under fault conditions provided in an embodiment of this application. In an optional embodiment, the operating condition further includes a fault condition; in the fault condition, the method further includes: Determine the type of failure in the battery system; When the fault type is controller fault, the faulty controller is determined from the master controller and at least one slave controller, and any controller other than the faulty controller is controlled to take over the control function corresponding to the faulty controller. When the fault type is battery pack fault, the faulty battery pack is identified from multiple battery packs, the charging process of the faulty battery pack is stopped, and at least one normal battery pack is controlled to supply power to the load, and the output power of the battery system is controlled not to exceed the first power. When the fault type is that both the controller and the battery pack fail simultaneously, at least one normal controller is controlled to supply power to at least one normal battery pack, and the output power of the battery system is controlled to be no higher than the second power, so that the vehicle decelerates and stops; wherein, the second power is less than the first power.

[0110] In some embodiments, such as Figure 7 As shown, the battery system's operating conditions also include fault conditions. The battery control unit can continuously or periodically monitor the operating status of the main controller, slave controllers, and each battery pack. When a fault is detected, the corresponding fault type is determined, and appropriate degradation control is executed according to different fault types.

[0111] When the fault type is controller fault, the faulty controller can be identified from the master controller and at least one slave controller, and the normal controller will take over the control functions corresponding to the faulty controller. For example, Figure 7 As shown, taking the failure of the main MCU as an example, when the main MCU fails, the slave MCU can take over the data processing and battery control functions corresponding to the main MCU. Simultaneously, the cross-validation function between the main and slave MCUs is disabled, causing the battery system to operate in a degraded manner. Since each battery pack can still supply power normally, the vehicle can maintain normal operation, and a fault indication will be output through the instrument panel. When the slave MCU fails, the corresponding control functions can also be taken over by the main MCU or another normal slave MCU.

[0112] When the fault type is a battery pack failure, the faulty battery pack can be identified and isolated from the current operating circuit. Taking a faulty battery pack A as an example, the relay corresponding to battery pack A can be disconnected and the bypass switch for battery pack A can be closed, allowing current to bypass battery pack A and battery pack B to independently supply power to the load. When battery pack B fails, battery pack B can be isolated in the same way, and battery pack A can continue to supply power.

[0113] Since the output power of the battery system decreases after part of the battery pack is removed, the output power of the battery system can be limited to not exceeding the first power level. For example, such as Figure 7 As shown, 70% of the normal maximum output power is used as the first power, so that the vehicle can continue to run in a reduced power state.

[0114] When both the controller and the battery pack fail simultaneously, at least one normal controller can take over the necessary control functions and isolate the failed battery pack, allowing at least one normal battery pack to continue supplying power to the load. In this case, the output power of the battery system is further limited to a second power level, and the second power level is less than the first power level. For example... Figure 7 As shown, the second power can be set to 30% of the normal maximum output power. Thus, in this degraded state, the output power of the drive motor can be limited, allowing the vehicle to maintain the necessary driving force and decelerate in an orderly manner, providing the driver with reaction time to leave the current lane or enter a safe area until the vehicle comes to a stop.

[0115] Therefore, a graded fault handling mechanism can be formed according to different situations such as controller failure, battery pack failure, and simultaneous failure of controller and battery pack. While ensuring that the faulty component is removed in time or taken over by the normal component, the available output power of the vehicle is reduced step by step according to the remaining control capability and power supply capability.

[0116] In the above embodiments, the control method of the battery system has been described in detail. This application also provides an embodiment of the control device for the battery system.

[0117] Figure 8 This is a schematic diagram of the structure of a control device for a battery system provided in an embodiment of this application. The battery system includes multiple battery packs connected in series, such as... Figure 8 As shown, the control device includes: The state of charge acquisition module 80 is used to acquire the effective state of charge of the battery pack. Operating condition determination module 81 is used to determine the operating conditions of the battery system based on the effective state of charge; the operating conditions include charging conditions and discharging conditions. The charging path control module 82 is used to adjust the charging current path of the battery pack according to the effective state of charge during the charging process, so as to regulate the charging process of the battery pack and reduce the difference in the state of charge of the battery pack in the end area of ​​the charging process. The discharge output control module 83 is used to adjust the discharge output state of the battery pack according to the effective state of charge during discharge operation, so as to suppress the increase of the difference in state of charge between battery packs.

[0118] In one optional embodiment, the battery system includes a battery control unit, which includes a main controller and at least one slave controller; the battery control unit is electrically connected to the battery pack; and a state of charge acquisition module is specifically used for: Obtain battery status data from the battery pack; The main controller determines the estimated first state of charge of each battery pack based on the battery status data. The second state of charge estimate for each battery pack is determined by at least one controller based on battery state data. The effective state of charge is determined based on the first state of charge estimate and the second state of charge estimate.

[0119] In one optional embodiment, determining the effective state of charge based on a first state of charge estimate and a second state of charge estimate includes: For the same battery pack, determine the charge difference between the first state-of-charge estimate and the second state-of-charge estimate; Determine whether the charge difference is less than the preset difference; If it is less than the first state of charge estimate and the second state of charge estimate, the effective state of charge is obtained by merging them. If it is not less than, proceed with the following steps: The first and second state of charge estimates are checked for deviation to determine the source of the deviation that causes the difference in charge. If the source of deviation is identified, the estimated state of charge corresponding to the source of deviation is corrected, and the effective state of charge is determined based on the corrected estimated state of charge. If the source of deviation is not determined, the lower of the first state of charge estimate and the second state of charge estimate is determined as the effective state of charge.

[0120] In one alternative embodiment, the master controller determines a first state of charge estimate using a filtering estimation algorithm; at least one slave controller determines a second state of charge estimate using an open-circuit voltage lookup table algorithm and an ampere-hour integration algorithm.

[0121] In one optional embodiment, the charging path control module is specifically used for: When the effective state of charge of each battery pack has not reached the charging end threshold, control the battery packs to be charged in series. If the state of charge of at least one target battery pack reaches the charging end threshold and the state of charge of at least one other battery pack does not reach the charging end threshold, the charging current path of the target battery pack is adjusted to suspend the charging of the target battery pack, while the other battery packs continue to charge. When the effective state of charge of each battery pack reaches the charging end threshold, the battery pack is controlled to perform constant voltage charging; the charging current corresponding to constant voltage charging is less than the charging current when none of the battery packs have reached the charging end threshold.

[0122] In one optional embodiment, each battery pack is connected to a corresponding switching assembly, and the charging current path includes a series charging path and a bypass charging path. When the control switch assembly is turned on to conduct the series charging path, the series charging path passes through the corresponding battery pack. When the control switch assembly is activated to enable the bypass charging path, the bypass charging path bypasses the corresponding battery pack. Correspondingly, the charging current path of the target battery pack is adjusted, including: Control the switching component corresponding to the target battery pack to activate the bypass charging path corresponding to the target battery pack.

[0123] In one optional embodiment, when the effective state of charge of each battery pack has not reached the charging end threshold, controlling the battery packs to perform series charging includes: Determine the charging request current for each battery pack; The target charging request current of the battery system is determined based on the minimum value among multiple charging request currents. Each battery pack is charged in series according to the target charging request current.

[0124] In one optional embodiment, the discharge output control module is specifically used for: If the effective state of charge of at least one target battery pack is less than the lower discharge threshold, and the effective state of charge of at least one other battery pack is not less than the lower discharge threshold, the target battery pack is controlled to stop outputting electrical energy, and at least one other battery pack is controlled to continue outputting electrical energy.

[0125] In one optional embodiment, the operating condition further includes a fault condition; such as Figure 8 As shown, the control device provided in this application also includes a lower limit threshold adjustment module 84 and a fault handling module 85; The lower limit threshold adjustment module 84 is used for: Obtain the state-affected parameters of the battery pack; the state-affected parameters include at least one of the following: the difference in state of charge between battery packs, the difference in battery temperature, the difference in battery health status, and the discharge rate; Based on the state influence parameters, the preset baseline discharge lower limit threshold is adjusted to obtain the discharge lower limit threshold. Among them, the lower discharge limit threshold is positively correlated with the difference in state of charge and the discharge rate, while the lower discharge limit threshold is negatively correlated with the difference in battery temperature and the difference in battery health status.

[0126] Fault handling module 85 is used for: In fault conditions, determine the type of fault in the battery system; When the fault type is controller fault, the faulty controller is determined from the master controller and at least one slave controller, and any controller other than the faulty controller is controlled to take over the control function corresponding to the faulty controller. When the fault type is battery pack fault, the faulty battery pack is identified from multiple battery packs, the charging process of the faulty battery pack is stopped, and at least one normal battery pack is controlled to supply power to the load, and the output power of the battery system is controlled not to exceed the first power. When the fault type is that both the controller and the battery pack fail simultaneously, at least one normal controller is controlled to supply power to at least one normal battery pack, and the output power of the battery system is controlled to be no higher than the second power, so that the vehicle decelerates and stops; wherein, the second power is less than the first power.

[0127] Figure 9 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application, such as... Figure 9 As shown, the vehicle includes: a battery system 97, a memory, and a processor; wherein the battery system 97 includes multiple battery packs connected in series; the battery system 97 and the memory are connected. Memory 90 is used to store computer programs; The processor 91 is used to execute computer programs to implement the steps of the control method for the battery system as described in the above embodiments.

[0128] The vehicles provided in this application embodiment may include, but are not limited to, sedans, sport utility vehicles (SUVs), multi-purpose vehicles (MPVs), off-road vehicles, pickup trucks, or other power-driven, non-rail-borne vehicles.

[0129] The processor 91 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 91 may be implemented using at least one of the following hardware forms: Digital Signal Processor (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 91 may also include a main processor and a coprocessor. The main processor, also known as the Central Processing Unit (CPU), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 91 may integrate a Graphics Processing Unit (GPU), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 91 may also include an Artificial Intelligence (AI) processor, which is used to handle computational operations related to machine learning.

[0130] The memory 90 may include one or more computer-readable storage media, which may be non-transitory. The memory 90 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 90 is used to store at least the following computer program 901, which, after being loaded and executed by the processor 91, is capable of implementing the relevant steps of the battery system control method disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 90 may also include an operating system 902 and data 903, and the storage method may be temporary or permanent storage. The operating system 902 may include Windows, Unix, Linux, etc. The data 903 may include, but is not limited to, relevant data involved in the battery system control method.

[0131] In some embodiments, the vehicle may also include a display screen 92, an input / output interface 93, a communication interface 94, a power supply 95, and a communication bus 96.

[0132] Those skilled in the art will understand that Figure 9 The structure shown does not constitute a limitation on the vehicle and may include more or fewer components than illustrated.

[0133] The vehicle provided in this application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the control method of the battery system in the above embodiments.

[0134] It should be noted that although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or sequentially, or requiring all illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A control method for a battery system, characterized in that, The battery system includes multiple battery packs connected in series; the method includes: Obtain the effective state of charge of the battery pack; The operating conditions of the battery system are determined based on the effective state of charge; the operating conditions include charging conditions and discharging conditions. In the charging condition, the charging current path of the battery pack is adjusted according to the effective state of charge in order to regulate the charging process of the battery pack and reduce the difference in the state of charge of the battery pack in the charging end region. During the discharge operation, the discharge output state of the battery pack is adjusted according to the effective state of charge to suppress the increase of the difference in state of charge between the battery packs.

2. The control method for the battery system as described in claim 1, characterized in that, The battery system includes a battery control unit, which includes a main controller and at least one slave controller; the battery control unit is electrically connected to the battery pack. The step of obtaining the effective state of charge of the battery pack includes: Obtain the battery status data of the battery pack; The main controller determines the first state of charge estimate of each battery pack based on the battery state data. The at least one slave controller determines a second state-of-charge estimate for each of the battery packs based on the battery state data. The effective state of charge is determined based on the first state of charge estimate and the second state of charge estimate.

3. The control method for the battery system as described in claim 2, characterized in that, Determining the effective state of charge based on the first state of charge estimate and the second state of charge estimate includes: For the same battery pack, determine the charge difference between the first state of charge estimate and the second state of charge estimate; Determine whether the charge difference is less than a preset difference; If it is less than, the first state of charge estimate and the second state of charge estimate are fused to obtain the effective state of charge; If it is not less than, proceed with the following steps: A deviation check is performed on the first state of charge estimate and the second state of charge estimate to determine the source of the deviation that causes the difference in charge. If the source of deviation is determined, the estimated state of charge corresponding to the source of deviation is corrected, and the effective state of charge is determined based on the corrected estimated state of charge. If the source of deviation is not determined, the lower of the first state of charge estimate and the second state of charge estimate is determined as the effective state of charge.

4. The control method for the battery system as described in claim 2, characterized in that, The main controller determines the first state-of-charge estimate using a filtering estimation algorithm; The at least one slave controller determines the second state of charge estimate using an open-circuit voltage lookup table algorithm and an ampere-hour integration algorithm.

5. The control method for the battery system as described in claim 1, characterized in that, In the charging condition, adjusting the charging current path of the battery pack according to the effective state of charge includes: If the effective state of charge of each of the battery packs has not reached the charging end threshold, control the battery packs to be charged in series. If the state of charge of at least one target battery pack reaches the charging end threshold and the state of charge of at least one other battery pack does not reach the charging end threshold, the charging current path of the target battery pack is adjusted to suspend the charging of the target battery pack, while the other battery packs continue to charge. When the effective state of charge of each battery pack reaches the charging end threshold, each battery pack is controlled to perform constant voltage charging; the charging current corresponding to the constant voltage charging is less than the charging current when none of the battery packs have reached the charging end threshold.

6. The control method for the battery system as described in claim 5, characterized in that, Each of the battery packs is connected to a corresponding switch assembly, and the charging current path includes a series charging path and a bypass charging path; When the switching assembly is controlled to activate the series charging path, the series charging path passes through the corresponding battery pack. When the switching assembly is controlled to activate the bypass charging path, the bypass charging path bypasses the corresponding battery pack. Correspondingly, adjusting the charging current path of the target battery pack includes: Control the switching component corresponding to the target battery pack to activate the bypass charging path corresponding to the target battery pack.

7. The control method for the battery system as described in claim 5, characterized in that, When the effective state of charge of each of the battery packs has not reached the charging end threshold, control the battery packs to be charged in series, including: Determine the charging request current corresponding to each of the battery packs; The target charging request current of the battery system is determined based on the minimum value among the plurality of the charging request currents; Each of the battery packs is charged in series according to the target charging request current.

8. The control method for the battery system as described in claim 1, characterized in that, In the discharge condition, adjusting the discharge output state of the battery pack according to the effective state of charge includes: If the effective state of charge of at least one target battery pack is less than the lower discharge threshold, and the effective state of charge of at least one other battery pack is not less than the lower discharge threshold, the target battery pack is controlled to stop outputting electrical energy, and at least one of the other battery packs is controlled to continue outputting electrical energy.

9. The control method for the battery system as described in claim 8, characterized in that, The method further includes: Obtain the state-affecting parameters of the battery pack; the state-affecting parameters include at least one of the following: the difference in state of charge between the battery packs, the difference in battery temperature, the difference in battery health status, and the discharge rate; Based on the state influence parameters, the preset baseline discharge lower limit threshold is adjusted to obtain the discharge lower limit threshold. The lower discharge limit threshold is positively correlated with the state of charge difference and the discharge rate, and negatively correlated with the battery temperature difference and the battery health state difference.

10. The control method for the battery system as described in claim 2, characterized in that, The operating conditions also include fault conditions; in the fault conditions, the method further includes: Determine the fault type of the battery system; When the fault type is a controller fault, the faulty controller is determined from the main controller and the at least one slave controller, and any controller other than the faulty controller is controlled to take over the control function corresponding to the faulty controller; When the fault type is a battery pack fault, the faulty battery pack is identified from the plurality of battery packs, the faulty battery pack is controlled to stop the charging process, and at least one normal battery pack is controlled to supply power to the load, and the output power of the battery system is controlled not to exceed the first power. When the fault type is that both the controller and the battery pack fail simultaneously, at least one normal controller is controlled to supply power to at least one normal battery pack, and the output power of the battery system is controlled not to exceed the second power, so that the vehicle decelerates and stops; wherein, the second power is less than the first power.

11. A control device for a battery system, characterized in that, The battery system includes multiple battery packs connected in series; the device includes: A state of charge acquisition module is used to acquire the effective state of charge of the battery pack; The operating condition determination module is used to determine the operating condition of the battery system based on the effective state of charge; the operating condition includes charging condition and discharging condition. The charging path control module is used to adjust the charging current path of the battery pack according to the effective state of charge during the charging operation, so as to regulate the charging process of the battery pack and reduce the state of charge difference of the battery pack in the charging end region. The discharge output control module is used to adjust the discharge output state of the battery pack according to the effective state of charge during the discharge operation, so as to suppress the increase of the difference in state of charge between the battery packs.

12. A vehicle, characterized in that, It includes a battery system, a memory, and a processor; the battery system includes multiple battery packs connected in series; the battery system is connected to the processor; The memory stores a computer program that can run on the processor, and when the processor executes the computer program, it implements the steps of the control method for the battery system according to any one of claims 1 to 10.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the control method for the battery system according to any one of claims 1 to 10.

Images