Battery system management method and battery system

Abstract

The invention provides a battery system management method and a battery system, and relates to the technical field of batteries, the battery system is connected with a load to supply power to the load, the battery system comprises a plurality of parallel battery branches and a master control, each battery branch comprises a battery pack and a slave control, each battery pack comprises a plurality of single batteries, and the slave control is in communication connection with the master control; the method comprises the steps that after charging or discharging is stopped, a battery system is placed in a standing stage, in the standing stage, the battery system is disconnected from a load, a plurality of battery branches connected in parallel are kept connected, and a master controller and a slave controller are powered on; judging whether the battery system needs to be balanced or not according to the inter-pack loop current between every two battery packs in the battery system; when the battery system needs to be equalized, the battery system is actively equalized in the standing stage; when the battery system does not need to be balanced, the battery system is placed in an off-line stage, and in the off-line stage, the plurality of parallel battery branches are disconnected, the master-slave controller is placed in a power-off state, and the battery system and the load are kept disconnected.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a battery system management method and a battery system. Background Art

[0002] With the rapid development of new energy technologies, the performance of battery packs, as the core components of energy storage, directly affects the performance and reliability of the entire system. In engineering machinery and large-scale energy storage systems, multi-branch battery packs are often connected in parallel to increase the total capacity and power supply reliability.

[0003] Traditional battery management systems often have problems such as poor balance between battery packs when dealing with multi-branch battery packs, resulting in reduced battery performance, shortened life and even safety hazards. Summary of the invention

[0004] In order to solve the above problems, the embodiments of the present disclosure propose a solution that enables a multi-branch battery pack to operate in a balanced manner.

[0005] According to a first aspect of an embodiment of the present disclosure, a battery system management method is provided, wherein the battery system is used to connect to a load to supply power to the load, the battery system comprises a plurality of parallel battery branches and a main controller, each battery branch comprises a battery pack and a slave controller for controlling the battery pack, each battery pack comprises a plurality of single cells, and the slave controller of each battery branch is communicatively connected to the main controller; the method comprises: after stopping charging or discharging, placing the battery system in a rest stage, in which the battery system is disconnected from the load, so that the plurality of parallel battery branches remain connected to each other and the battery packs are kept in a rest state; The master controller and the slave controller are both kept in a powered-on state; in the static stage, whether the battery system needs to be battery balanced is determined according to the inter-pack ring current between every two battery packs in the battery system; when it is determined that the battery system needs to be battery balanced, the battery system is actively balanced in the static stage; and when it is determined that the battery system does not need to be battery balanced, the battery system is placed in an offline stage, in which the multiple parallel battery branches are disconnected from each other, the master controller and the slave controller are placed in a powered-off state, and the battery system is kept disconnected from the load.

[0006] According to a second aspect of an embodiment of the present disclosure, there is provided a battery system, the battery system being used to be connected to a load to supply power to the load, the battery system comprising a plurality of parallel battery branches and a main controller, each battery branch comprising a battery pack and a slave controller for controlling the battery pack, each battery pack comprising a plurality of single cells, and the slave controller of each battery branch being communicatively connected to the main controller; wherein the main controller is configured to: after stopping charging or discharging, place the battery system in a resting stage, in which the battery system is disconnected from the load so that the plurality of parallel battery branches remain connected to each other and Keep both the master controller and the slave controller in a powered-on state; in the static stage, determine whether the battery system needs to be battery balanced according to the inter-pack ring current between every two battery packs in the battery system; when it is determined that the battery system needs to be battery balanced, actively balance the battery system in the static stage; and when it is determined that the battery system does not need to be battery balanced, place the battery system in an offline stage, in which the multiple parallel battery branches are disconnected from each other, the master controller and the slave controller are placed in a powered-off state, and the battery system is disconnected from the load.

[0007] In the technical solutions according to various aspects of the present disclosure, firstly, through the balancing technology, the voltage and capacity of each battery cell in the battery pack can be adjusted to keep them as consistent as possible, thereby improving the balance between the battery packs and further improving the safety of the battery system.

[0008] Secondly, active balancing is fast and efficient, and the entire balancing process can be completed in a relatively short time. Using active balancing during the static stage can quickly reduce or eliminate the voltage differences between battery packs and efficiently balance the status of each battery pack.

[0009] Finally, the inter-pack ring current can directly reflect the inconsistency between battery packs. Using the inter-pack ring current as a criterion for judging whether the battery system needs to be balanced is conducive to improving the balance between battery packs, thereby improving the quality of battery balancing management, optimizing energy efficiency and ensuring system safety.

[0010] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 is a schematic diagram of the structure of a battery system according to some embodiments of the present disclosure.

[0013] Figure 2 is a flowchart of a battery system management method according to some embodiments of the present disclosure.

[0014] Figure 3 Schematic diagram of energy transfer for active balancing between battery packs according to some embodiments of the present disclosure.

[0015] Figure 4 Schematic diagram of a circuit for active balancing of a battery pack according to some embodiments of the present disclosure.

[0016] Figure 5 is a flow chart of the static phase according to some embodiments of the present disclosure.

[0017] Figure 6 It is a schematic diagram of turning on passive balancing in a battery pack according to some embodiments of the present disclosure.

[0018] Figure 7 is a schematic diagram of a passive balancing circuit in a battery pack according to some embodiments of the present disclosure.

[0019] Figure 8 It is a flowchart of entering the offline phase according to some embodiments of the present disclosure.

[0020] Fig. 9 is a flow chart of the discharge phase according to some embodiments of the present disclosure.

[0021] Fig.10 is a flow chart of the charging stage according to some embodiments of the present disclosure.

[0022] Fig.11 is a schematic diagram of a comprehensive management method for a battery system according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0024] Unless specifically stated otherwise, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0025] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0026] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0027] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0028] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0029] Figure 1 is a schematic diagram of the structure of a battery system according to some embodiments of the present disclosure.

[0030] like Figure 1 As shown, the battery system is used to connect to a load to supply power to the load. In some embodiments, the battery system is applied to a vehicle, and the load is a load of the vehicle, such as a vehicle control unit (VCU), a motor control unit (MCU), etc.

[0031] The battery system includes multiple parallel battery branches and a main controller (also called main control, main board or upper controller). Each battery branch includes a battery pack (such as battery pack A or battery pack B) and a slave controller (also called slave control, slave board or lower controller) for controlling the battery pack. Each battery pack includes multiple single cells. The slave controllers of each branch are aggregated to the main controller for management. The slave controllers of each battery branch are connected to the main controller for communication to achieve data sharing and collaborative control.

[0032] In some embodiments, each battery pack is connected to a load or a charging terminal via a main relay, and the on and off of the main relay can be controlled by a slave controller. In some embodiments, the battery pack is connected to a slave controller for controlling the battery pack via a shunt.

[0033] In some embodiments, the main controller includes one or more of a charging control module, a discharging control module, a communication module, a balancing control module, a power supply module, and a fault diagnosis processing module.

[0034] In some embodiments, the battery system further includes a plurality of acquisition boards, each of which is used to monitor a plurality of single cells. For example, one or more of the voltage (V) and temperature (T) of each single cell in the plurality of single cells is monitored. In some embodiments, the acquisition board is connected in communication with the main controller and the slave controller for controlling the battery pack where the single cell monitored by the acquisition board is located, so as to realize data sharing and collaborative control. For example, the acquisition board collects the voltage (V) and temperature (T) of the single cell and transmits them to the slave controller. The slave controller can perform preliminary aggregation and packaging of the collected data and transmit it to the main controller, and control the on and off of the main relay according to the instructions issued by the main controller. The main controller performs modular processing on the data and sends the corresponding control instructions to the slave controller.

[0035] In some embodiments, the master controller, slave controller and acquisition board may be referred to as a battery management system (BMS). The BMS system may adopt distributed control. The BMS system may have a real-time monitoring function, capable of monitoring one or more parameters of the voltage, current, and temperature of each branch battery pack and / or single battery.

[0036] Figure 2 is a flowchart of a battery system management method according to some embodiments of the present disclosure.

[0037] like Figure 2 As shown, in step S210, after stopping charging or discharging, the battery system is placed in a static stage. Here, in the static stage, the battery system is disconnected from the load, so that multiple parallel battery branches remain connected to each other and the master controller and the slave controller remain powered on (also called a non-sleeping state). The acquisition board can, for example, remain powered on. In the embodiment of ISI, in the case of a faulty battery branch, keeping multiple parallel battery branches connected to each other means keeping battery branches other than the faulty battery branch connected to each other.

[0038] In step S220 , during the static phase, it is determined whether battery balancing (hereinafter referred to as balancing) is required for the battery system according to the inter-pack ring current between every two battery packs in the battery system.

[0039] The electromotive force between battery packs in a parallel circuit may differ greatly, causing the battery pack with a large electromotive force to discharge to the battery pack with a small electromotive force, forming an inter-pack ring current between the parallel battery packs. The inter-pack ring current can directly reflect the inconsistency between battery packs. Cir For example, according to I Cir =(U A -U B ) / (R A +R B ) is calculated, where U A , U B is the voltage of two parallel battery packs, R A , R B are the internal resistances of the two battery packs.

[0040] When it is determined that the battery system needs to be balanced, step S230 is executed to actively balance the battery system in the static stage. Figure 3 FIG. 1 is a schematic diagram of energy transfer between battery packs according to some embodiments of the present disclosure. Figure 3 As shown, during active balancing, electrical energy is transferred from battery packs with high energy to battery packs with low energy.

[0041] When it is determined that the battery system does not need to be balanced, step S240 is executed to put the battery system into an offline stage. Here, in the offline stage, multiple parallel battery branches are disconnected from each other, the master controller and the slave controller are placed in a power-off state (also called a dormant state), and the battery system is disconnected from the load.

[0042] First, through the balancing technology, the voltage and capacity of each battery cell in the battery pack can be adjusted to keep them as consistent as possible, thereby improving the efficiency and safety of the battery pack. It is also beneficial to prevent the battery cells from being overcharged or over-discharged and protect the battery from damage. Otherwise, it will accelerate the aging process of the battery and reduce the overall performance of the battery pack. After the battery pack is charged, it will be left to stand for a period of time, which will help the battery voltage to naturally drop to a stable range, thereby maintaining the stable state of the battery to ensure that the internal chemical reaction of the battery tends to balance and reduce polarization. After the battery pack is discharged, it is left to stand for a period of time, which can help to recover some of the lost battery capacity and improve the overall performance. In the above embodiment, after stopping charging or discharging, it is determined whether the battery system needs to be balanced. If necessary, it will enter the static stage and perform balancing, which is beneficial to improve the balance and service life of the battery system.

[0043] Secondly, on the one hand, active balancing involves energy transfer between battery packs, which requires that the two battery packs are connected. On the other hand, active balancing is fast and efficient, and the entire balancing process can be completed in a relatively short time. However, the active balancing process requires the ability to accurately detect parameters such as voltage, current and / or temperature in the battery pack, which requires that the master controller and the slave controller remain powered on. In the above embodiment, a static phase is provided, during which multiple parallel battery branches remain interconnected, and both the master controller and the slave controller remain powered on, meeting the requirements of active balancing. When the battery system needs to be balanced, the above embodiment uses active balancing for balancing during the static phase, which can quickly reduce or eliminate the voltage differences between the battery packs and efficiently balance the states of each battery pack.

[0044] Finally, the inter-pack ring current can directly reflect the inconsistency between battery packs. Using the inter-pack ring current as a criterion for judging whether the battery system needs to be balanced is conducive to improving the balance between battery packs, thereby improving the quality of battery balancing management, optimizing energy efficiency and ensuring system safety.

[0045] In summary, the above embodiments are conducive to improving the overall performance and intelligent management and control of the battery system, and can provide a basis for the efficient use of large-scale battery systems.

[0046] In some embodiments, the master controller is configured to place the battery system in a rest stage after stopping charging or discharging, in which the battery system is disconnected from the load, multiple parallel battery branches remain interconnected, and both the master controller and the slave controller remain powered on; in the rest stage, whether battery balancing of the battery system is required is determined based on the inter-pack ring current between every two battery packs in the battery system; when it is determined that battery balancing of the battery system is required, the battery system is actively balanced in the rest stage; and when it is determined that battery balancing of the battery system is not required, the battery system is placed in an offline stage, in which multiple parallel battery branches are disconnected from each other, the master controller and the slave controller are placed in a power-off state, and the battery system is disconnected from the load.

[0047] In some embodiments, when at least one of the inter-pack ring currents between every two battery packs in the battery system is greater than or equal to a preset threshold, it is determined that the battery system needs to be cell-balanced, and when the maximum inter-pack ring current between every two battery packs in the battery system is less than the preset threshold, it is determined that the battery system does not need to be cell-balanced. That is, in the case of multiple inter-pack ring currents, whether the maximum inter-pack ring current is greater than the preset threshold is used as a criterion for determining whether the battery system needs to be cell-balanced.

[0048] In the above embodiment, as long as there is at least one inter-pack ring current greater than or equal to the preset threshold, it is determined that the battery system needs to be balanced, which is beneficial to improving the balance between battery packs. When the maximum inter-pack ring current between every two battery packs is less than the preset threshold, it is determined that the battery system does not need to be balanced. The maximum inter-pack ring current is less than the preset threshold, indicating that the multiple battery packs in the battery system have good balance. At this time, no further balancing is required, which is beneficial to simplifying the process.

[0049] In some embodiments, actively balancing the battery system in the static stage includes: actively balancing between battery packs of at least two battery branches corresponding to the maximum inter-pack ring current.

[0050] In some embodiments, active balancing is performed between the battery packs of the two battery branches corresponding to the maximum inter-packet ring current, including: transferring electricity between the battery packs of the two battery branches through an inter-packet energy storage device disposed between the two battery branches.

[0051] Figure 4 Schematic diagram of a circuit for active balancing between battery packs according to some embodiments of the present disclosure.

[0052] like Figure 3 and Figure 4 As shown, the inter-packet energy storage device includes, for example, one or more of a transformer, an inductor, and a supercapacitor.

[0053] Figure 3 and Figure 4 In the embodiment, each battery pack may include B1, B2, ... n The slave controller can control the balancing switches on the battery branch (e.g. balancing switch S1, balancing switch S2, etc.) n ), the main controller can control the balancing switch S between the two battery branches 总 When the balancing switches on the two battery branches and the balancing switch between the two battery branches are closed, active balancing can be performed between the two battery branches.

[0054] In some embodiments, the battery system is actively balanced in the rest phase until an active balancing target is reached or until active balancing lasts for a preset time (also referred to as rest phase defined time), and then the battery system is placed in an offline phase.

[0055] If active balancing lasts too long, the battery power may be over-consumed or even over-discharged, thereby affecting the performance and life of the battery system. In the above embodiment, when active balancing reaches the active balancing target or the active balancing lasts for a preset time, the active balancing ends and enters the offline stage, which is conducive to ensuring the efficiency and safety of the balancing process and protecting the performance and life of the battery system.

[0056] As some implementations, the active balancing target is that after active balancing, the inter-pack ring current between every two battery packs in the battery system is less than a preset threshold.

[0057] As some implementations, the preset duration is greater than or equal to 1 hour and less than or equal to 2 hours.

[0058] In some embodiments, active balancing is performed between the battery packs of the two battery branches corresponding to the maximum inter-pack ring current so that the inter-pack ring current between the battery packs of the two battery branches is less than a preset threshold value, and the active balancing time does not reach the preset time length, and active balancing is performed between the battery packs of the two battery branches corresponding to the current maximum inter-pack ring current. For example, in a battery system including battery pack A, battery pack B, battery pack C, and battery pack D, and the inter-pack ring current between battery pack A and battery pack B is the largest and greater than the preset threshold value, active balancing can be performed between battery pack A and battery pack B. Thereafter, if, due to active balancing, the inter-pack ring current between battery pack A and battery pack B is less than the preset threshold value, the active balancing time does not reach the preset time length, and the current maximum inter-pack ring current exists between battery pack C and battery pack D, active balancing can be performed between battery pack C and battery pack D.

[0059] In some embodiments, when actively balancing the battery system in the static stage, if the active balancing target is not reached after the active balancing continues for a preset time, the battery system is placed in an offline stage and passively balanced in the offline stage.

[0060] It should be understood that passive balancing does not require the ability to accurately detect parameters such as voltage, current and / or temperature in the battery pack, but the balancing time is too long and the balancing efficiency is low.

[0061] As mentioned above, if active balancing lasts too long, it may cause excessive consumption of battery power or even over-discharge, thereby affecting the performance and life of the battery system. The above embodiment comprehensively considers the advantages and disadvantages of active balancing and passive balancing. If the battery needs to be balanced, active balancing is first performed in the static stage, which is conducive to efficiently balancing the battery pack state; thereafter, if the active balancing target is still not achieved, passive balancing is performed in the offline stage, which is conducive to achieving balancing while avoiding affecting the performance and life of the battery pack. In short, by combining active balancing and passive balancing, it is beneficial to make full use of the state transition process of the battery pack and maximize the balancing efficiency.

[0062] In addition, balancing management during the static and offline stages will not affect the normal use of the battery pack, but can also achieve intelligent monitoring and balancing control of consistency differences between multi-branch battery packs, which is beneficial to improving the balance and service life of the battery system.

[0063] Figure 5 is a schematic diagram of the process of the static stage according to some embodiments of the present disclosure. Figure 5 and one A specific example is given to describe the resting phase.

[0064] It should be understood that in the static stage, the power management modules of the master controller and slave controller of the BMS system maintain power supply to the master controller and the slave controller. The balancing judgment condition is the size of the ring current generated by the voltage difference between the battery packs. The balancing method is active balancing, and the active balancing limit time is 1-2h.

[0065] In step S501, the static phase is entered.

[0066] In step S502, the standstill process starts.

[0067] In step S503, the inter-pack loop current (i.e., inter-pack loop current) between battery packs is monitored. It should be understood that the BMS system integrates a high-precision current monitoring module, which is assigned to each branch and monitors the current size of each branch in real time. The monitored data is transmitted to the control unit (e.g., master controller, slave controller) in real time through a high-speed communication interface, so as to accurately grasp the difference in health status between the battery packs inside the battery pack.

[0068] In steps S504 and S505, the size of the inter-packet ring current is determined to determine the inter-packet ring current I Cir Is it greater than the preset threshold I Cirmax The preset threshold is also called the inter-packet ring current threshold. Cir According to I Cir =(U A -U B ) / (R A +R B ) is calculated, where U A , U B is the voltage of any two parallel battery packs, R A , R B are the internal resistances of the two battery packs.

[0069] In step S506, if the ring current Icycle is less than the preset threshold, the balancing module of the master controller does not perform active balancing (for example, it can be turned off). In some embodiments, the master controller and the slave controller enter a low-power sleep mode. In other embodiments, in order to better monitor the status of the battery system, the master controller and the slave controller may not enter a low-power sleep mode, but continue to monitor the battery pack status.

[0070] If the inter-pack loop current is greater than the preset threshold, steps S507 and S508 are executed. That is, once it is confirmed that there is a need for balancing, the high voltage connection is maintained, and the BMS system starts the active balancing program to actively transfer the energy in the high-power battery pack to the low-power battery pack to reduce or eliminate the voltage difference between the battery packs and achieve battery pack balancing.

[0071] In step S509, the duration of active balancing (ie, static balancing duration) is determined. bal Whether the preset time t is reached max For example, limiting it to 1-2 hours is conducive to ensuring the efficiency and safety of the balancing process, and is also conducive to ensuring that the balancing task is completed within a reasonable time frame.

[0072] In some embodiments, when active balancing continues for a preset period of time and has not yet reached the active balancing target, the passive balancing target is determined before entering the offline stage by: calculating the single pack capacity of each battery pack; calculating the average capacity based on the single pack capacity of each battery pack; and determining whether the battery pack needs to be passively balanced and the corresponding passive balancing time based on the difference between the single pack capacity of each battery pack and the average capacity. Here, the passive balancing target includes whether each battery pack needs to be passively balanced and the corresponding passive balancing time. Subsequently, in the offline stage, the battery packs that need to be passively balanced are discharged until the corresponding passive balancing time is reached.

[0073] In the related art, balancing is usually only performed at the single-cell level, and the single-cell pressure difference is used as the balancing judgment standard. The balancing time is long, the algorithm accuracy requirements are high, and the controller data processing capabilities are required to be higher. In the above embodiment, the passive balancing time is determined based on the single-pack capacity, so that the battery pack that needs to be passively balanced is discharged until the corresponding passive balancing time is reached. Balancing is performed at the battery pack level, and the capacity difference between the single-pack capacity and the average capacity of the battery pack is used as the balancing judgment standard to achieve simultaneous balancing of the entire battery pack. This can greatly shorten the balancing time, reduce the probability of circulating current between packs, and meet the needs of efficient balancing of multi-battery pack systems.

[0074] In other embodiments, whether the battery pack needs to be passively balanced and the corresponding passive balancing time can be determined based on the difference in the single-pack capacity of the two battery packs. For example, assuming that there are three battery packs, namely battery pack A, battery pack B, and battery pack C, and the inter-pack capacity difference between battery pack A and battery pack B is the largest, then battery pack A needs to be balanced, and the balancing time is determined based on the inter-pack capacity difference between battery pack A and battery pack B.

[0075] Figure 6 is a schematic diagram of starting passive balancing in a battery pack according to some embodiments of the present disclosure, Figure 7is a schematic diagram of a passive balancing circuit in a battery pack according to some embodiments of the present disclosure.

[0076] like Figure 6 and Figure 7 As shown, when performing passive balancing, the master controller sends a balancing instruction to the slave controller, and the slave controller controls the acquisition board (for example, acquisition board 1 to acquisition board n, where n is a natural number) accordingly, and the acquisition board controls the balancing switch.

[0077] In some embodiments, there is a balancing switch between the balancing resistor and the single battery, and the balancing channel can be turned on / off by controlling the closing / opening of the balancing switch. Figure 6 and Figure 7 As shown, the acquisition board 1 controls the balancing switch S1 of the single cell B1. When the balancing switch is closed, the single cell B1 can discharge through the balancing resistor R1, and the balancing current is I1. The acquisition board 1 also controls the balancing switch S2 of the single cell B2. When the balancing switch is closed, the single cell B2 can discharge through the balancing resistor R2, and the balancing current is I2. n The balancing switch S n , when the balancing switch is closed, the single cell B n The balancing resistor R n Discharge, the balancing current is I n .

[0078] In some embodiments, the single pack capacity of each battery pack is calculated based on an open circuit voltage-state of charge (OCV-SOC) curve and a table lookup method, so that the calculation result is more accurate.

[0079] For example, the single pack capacity Q of battery pack A can be calculated by table lookup based on the OCV-SOC curve. A =Q rate *SOC A , where Q rate The state of charge (SOC) of the battery is used to reflect the remaining capacity of the battery, which refers to the ratio of the current remaining charge of the battery to the rated charge. A Refers to the SOC of battery pack A in a static state.

[0080] Figure 8 It is a flowchart of entering the offline phase according to some embodiments of the present disclosure.

[0081] In the offline stage, the master controller sends the balancing instruction to the slave controller and then enters the low-power sleep mode. The balancing method adopts passive dissipation balancing, and the capacity calculation method adopts the table lookup method.

[0082] In steps S801, S802, S803 and S804, if the active balancing continues for a preset time in the static stage and still fails to reach the balancing target, the main controller calculates the single pack capacity Q by the table lookup method according to the OCV-SOC curve before the static balancing ends. A =Q rate *SOC A , and then calculate the capacity difference between the battery packs. The capacity difference between the battery packs is, for example, the difference between the single-pack capacity and the average capacity of the battery pack, or the difference between the single-pack capacities of two battery packs.

[0083] In steps S805, S806, S807 and S808, the required balancing time t of the battery pack is calculated according to the capacity difference between the battery packs. Calcu The balancing instruction is sent to all target acquisition boards, and the master controller and the slave controller enter a low-power sleep mode and then enter an offline phase. The target acquisition board is, for example, an acquisition board corresponding to a single cell that needs to be balanced.

[0084] In steps S809 and S810, after receiving the balancing instruction, the acquisition board uses a passive dissipation balancing method to balance the power of each battery module according to the preset balancing strategy. For example, the acquisition board opens the balancing channel according to the instruction until the balancing time t Passbal ≥Battery pack required balancing time t Calcu .

[0085] In step S811 , when the power balancing of the target battery module is completed, the balancing channel is closed.

[0086] The discharge process is described below in conjunction with some embodiments.

[0087] In some embodiments, when the battery is in a discharging state and a battery pack in a battery branch circuit fails or has performance degradation, the connection between the battery branch circuit where the battery pack with the failure or performance degradation is located and other battery branches is cut off. This is conducive to achieving electrical isolation of the battery pack with the failure or performance degradation from the main discharge circuit, so as to prevent the spread of the failure and ensure the safety of the battery system.

[0088] In other embodiments, when a battery pack fails or has degraded performance, the main controller can determine whether the faulty branch can be directly disconnected and the total output power of the remaining branches can support the vehicle to continue to complete the operation or drive to a safe area based on the sum of the maximum sustainable output power allowed by the battery pack uploaded from the controller of all branches. If the faulty branch can be directly disconnected and the total output power of the remaining branches can support the vehicle to continue to complete the operation or drive to a safe area, the faulty branch is disconnected, and the vehicle continues to complete the operation or drive to a safe area. Otherwise, the main circuit (i.e., the circuit between the battery system and the load) is disconnected, and the vehicle stops running.

[0089] In some embodiments, the charging and discharging strategy is dynamically adjusted according to the battery pack state and external demand. The external demand includes, for example, power demand and / or load demand. For example, when the battery is in a discharging state, a power reduction scheme can be formulated according to the power demand and the load demand to dynamically adjust the discharge power of the remaining battery pack.

[0090] Fig. 9 is a flow chart of the discharge phase according to some embodiments of the present disclosure.

[0091] In step S901, the battery system is in a discharging stage, that is, in a discharging state. The battery system includes, for example, battery pack A, battery pack B, battery pack C, ..., battery pack n, etc.

[0092] In step S902, the fault diagnosis module performs real-time detection.

[0093] In step S903, it is determined whether a branch battery pack is detected to be faulty or has performance degradation. If the determination result is yes, steps S904 and S905 are executed. If the determination result is no, steps S901 and S902 are continued.

[0094] In steps S904 and S905, when a battery pack (e.g., battery pack A) is detected to be faulty or has performance degradation, the fault detection module of the master controller confirms that battery pack A is the source of the fault, and then quickly processes the fault signal and sends a relay cut-off instruction to the slave controller. After receiving the relevant instruction, the slave controller cuts off the main relay of the branch where battery pack A is located, realizes the electrical isolation of battery pack A from the main discharge circuit to prevent the fault from spreading, and records the fault information.

[0095] Step S906: After the faulty branch is cut off, the main controller in the BMS system immediately starts the remaining power evaluation program to calculate the total available discharge power P of the remaining healthy branches (assuming that they are battery packs B, C, D, ... n, etc.). total =P B +P c +P D +…+P n Here, the discharge power calculation formula is P = UI; where U is the output voltage of the battery pack in volts (V), and I is the discharge current in amperes (A).

[0096] In step S907, the BMS system determines the critical load and non-critical load by determining the vehicle power output demand and analyzing the current system load demand. The power output demand can be determined based on the input power required by the high-voltage accessories and the drive motor. In some embodiments, the power output demand can be adjusted by limiting acceleration performance.

[0097] In steps S908, S909, and S910, according to the power demand P power and load demand P load , the BMS system formulates a power reduction plan to dynamically adjust the discharge power P of the remaining battery pack total , so that the remaining battery pack discharge power P total ≥P power +P load , in order to maintain the basic normal driving, operation and power supply of key systems of the vehicle. For example, the overall power demand can be reduced by reducing the power of non-critical loads or adjusting the working mode of critical loads. Critical loads include, for example, electrical loads that are critical to vehicle performance and safety. If these loads fail, the vehicle may not be able to operate normally or there may be safety hazards, such as one or more of VCU, MCU, and sensors. Non-critical loads include, for example, electrical loads that have little impact on vehicle performance and safety. The failure of such loads will not cause the vehicle to be unable to operate or there may be major safety hazards, such as one or more of air conditioning, audio, and ambient lighting. In some embodiments, the user can also be notified during the power reduction process to ensure user experience. For example, the user can be informed of the current power reduction status and / or expected impact through the system interface and / or remote communication.

[0098] Step S911, the BMS system continuously monitors the discharge power P of the remaining battery packs total .

[0099] Step S919, if the adjusted total discharge power (i.e., the discharge power P of the remaining battery pack) total ) is lower than the system preset minimum power requirement P limitlow , that is, P total ≤P limitlow , the BMS system can shut down safely. For example, trigger emergency protection measures, notify the driver of the fault through the dashboard or mobile phone APP, ensure that the vehicle can drive safely to the nearest service station or charging station, and then disconnect the main circuit and power supply of the entire battery system. Minimum power requirement P limitlow It is the power that can keep the vehicle running at a lower but stable power.

[0100] In step S913, the faulty branch battery pack is repaired or replaced.

[0101] In steps S914, S915, and S916, after the faulty branch is repaired, the total discharge capacity of the system is re-evaluated, and after confirming that the operation requirements are met and there are no other faults, the system operation is restored.

[0102] The charging process is described below in conjunction with some embodiments.

[0103] In some embodiments, the battery packs of multiple branches can be charged simultaneously, which is beneficial to improve the charging efficiency compared to charging the battery packs one by one.

[0104] In some embodiments, when the voltage of the battery pack reaches an upper limit value, the SOC reaches an upper limit value, or the charging current drops to a lower limit value (eg, an extremely low level), the battery pack is considered to be fully charged.

[0105] In some embodiments, when one or more battery packs are fully charged during the charging process, cutting off the branch where the one or more fully charged battery packs are located is beneficial to preventing overcharging and also beneficial to avoiding stopping receiving energy due to some batteries reaching the cutoff voltage too early, thereby improving charging efficiency.

[0106] In some embodiments, when one or more battery packs are fully charged during the charging process, the charging strategy of the battery system is adjusted based on the charging status and charging requirements of the remaining uncharged battery packs. In some embodiments, the charging strategy can be adjusted based on power redistribution and / or charging rate control methods.

[0107] Power redistribution includes, for example, intelligently adjusting the charging power P of each branch according to the charging voltage and / or charging current of each branch. Chg distribution to optimize overall charging efficiency.

[0108] The charge rate control includes, for example, limiting the charge rate of all branches to not exceed the maximum allowable continuous charge rate C. conti The maximum allowable continuous charge rate is the maximum allowable continuous charge rate specified by the battery manufacturer. If it is detected that the charge rate of a branch is close to this limit, the charging power of the branch or the entire system is automatically reduced. If this limit is exceeded, the charging power of the branch (or the entire battery system if necessary) is adjusted to the maximum allowable continuous charge rate and maintained until all battery packs are fully charged. Charging rate control can prevent the output current from being greater than the maximum allowable charging current of the battery pack, which is beneficial to ensure the charging safety of the entire system.

[0109] As some implementation methods, the charging strategy includes, for example: if the total output current of the charging device can meet the needs of the battery packs of all branches, charging is performed according to the maximum allowable charging current of each battery pack; if it is not enough to meet all needs, the total output current is distributed to each branch in proportion, and the output current is distributed according to the SOC of the battery packs of each branch, with priority given to charging the battery packs with lower SOC to balance the power of the entire battery system.

[0110] Fig.10 is a flow chart of the charging stage according to some embodiments of the present disclosure.

[0111] like Fig.10 As shown, in steps S1001 and S1002, the battery system is in the charging process, and the BMS system monitors one or more parameters of the voltage, current, temperature, and SOC of each branch battery pack in real time.

[0112] In steps S1003 and S1004, when it is detected that the battery pack of a branch has reached the preset full condition, the branch is considered to be fully charged. The preset full condition is, for example, SOC>SOC Chgmax .SOC Chgmax Set the full threshold value for the preset.

[0113] In step S1005, after confirming that a branch battery pack is fully charged, the main controller immediately sends a relay cut-off instruction to the slave controller of the branch. After receiving the relevant instruction, the slave controller controls the relay to cut off the charging circuit of the branch to prevent overcharging.

[0114] In step S1006, based on the charging state and charging demand of the remaining uncharged branch battery packs, the BMS dynamically adjusts the charging strategy of the battery system. This adjustment process includes but is not limited to one or more of steps S1007 and S1008.

[0115] In step S1007, power redistribution is performed. The charging power P of each branch is intelligently adjusted according to the charging voltage and charging current of each branch. Chg distribution to optimize overall charging efficiency.

[0116] In step S1008, the charging rate is controlled to ensure that the charging rate of all branches does not exceed the maximum allowable continuous charging rate C conti If it is detected that the charging rate of a branch is close to this limit, the BMS will automatically reduce the charging power of the branch or the entire system. If it exceeds this limit, the charging power of the branch (or the entire system if necessary) will be adjusted to the highest allowed continuous charging rate and maintained until all battery packs are fully charged.

[0117] In step 1009, charging abnormality monitoring is performed. In some embodiments, charging abnormality monitoring may be performed continuously throughout the entire charging process.

[0118] Fig.11 is a schematic diagram of a comprehensive management method for a battery system according to some embodiments of the present disclosure.

[0119] like Fig.11 As shown, the present disclosure provides a comprehensive management method for a battery system involving a discharge phase, a charge phase, a rest phase, and an offline phase.

[0120] In steps S1101 and S1102, the battery system is in the discharge stage. When a battery pack in a branch fails, the BMS system cuts off the main relay of the branch, so that the battery pack in the branch is disconnected from the main circuit. After cutting off the faulty branch, the BMS system adjusts the discharge power of the remaining branch battery packs according to the preset power reduction strategy to continue to support the operation of the system. If the discharge power of the remaining branch battery pack is less than the minimum power requirement, the main circuit is disconnected and the battery pack is stopped.

[0121] In steps S1103 and S1104, the battery system is in the charging stage. When the BMS system detects that a branch battery pack is full, it automatically sends a cut-off signal to the main relay of the branch to stop charging the branch. According to the charging status of the remaining branch battery packs, the charging strategy is dynamically adjusted, including adjusting the charging power to ensure that the charging rate does not exceed the maximum allowable continuous charging rate. If the charging rate still exceeds the limit after adjustment, the charging power is automatically adjusted to the maximum allowable continuous rate and maintained in this state until all battery packs are fully charged.

[0122] It should be understood that there is no restriction on the order of the discharge phase and the charge phase, and steps S1101 and S1102 may be placed after steps S1103 and S1104.

[0123] In steps S1104, S1105, and S1106, the battery system is in the static stage. After the vehicle is powered off and put into sleep mode, the master and slave controllers in the BMS system are not powered off, and decide whether to sleep immediately based on the size of the inter-packet loop current. If the inter-packet loop current is greater than the threshold, the high-voltage connection is maintained for balancing within a limited time. If the balancing fails to reach the balancing target within the limited time of the static stage, the BMS system calculates the single pack capacity based on the OCV-SOC curve before the static balancing ends, and then calculates the balancing time required for each pack.

[0124] In step S1107, the battery system is in the offline stage, the master and slave controllers in the BMS system are powered off and enter the dormant state, and the acquisition board is not powered off. When the balancing time is calculated in step S1106, the acquisition board can open the balancing channel for balancing according to the balancing time carried in the received balancing instruction, and finally make the capacity difference between the batteries meet the balancing closing condition.

[0125] The above embodiment provides an efficient charge and discharge control management strategy for a multi-branch battery system. The system realizes real-time monitoring, precise control and balanced management of multi-branch battery packs through intelligent management strategies, thereby improving the charge and discharge efficiency of the battery pack, extending the service life and ensuring system safety.

[0126] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other.

[0127] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0128] Those skilled in the art will appreciate that the embodiments of the present disclosure may be provided as methods, systems, or computer program products. Therefore, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present disclosure may take the form of a computer program product implemented on one or more computer-usable non-transient storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0129] The present disclosure is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present disclosure. It should be understood that the functions specified in one or more processes in the flowchart and / or one or more blocks in the block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions specified in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0130] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0131] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0132] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A battery system management method, wherein the battery system is used to connect to a load to supply power to the load, the battery system comprises a plurality of parallel battery branches and a master controller, each battery branch comprises a battery pack and a slave controller for controlling the battery pack, each battery pack comprises a plurality of single cells, and the slave controller of each battery branch is communicatively connected to the master controller; The method comprises: After stopping charging or discharging, placing the battery system in a rest stage, in which the battery system is disconnected from the load, so that the multiple parallel battery branches remain connected to each other and both the master controller and the slave controller remain powered on; In the static stage, judging whether it is necessary to perform battery balancing on the battery system according to the inter-pack ring current between every two battery packs in the battery system; When it is determined that the battery system needs to be balanced, actively balancing the battery system in the static stage; as well as When it is determined that battery balancing of the battery system is not required, the battery system is placed in an offline stage. In the offline stage, the multiple parallel battery branches are disconnected from each other, the main controller and the slave controller are placed in a power-off state, and the battery system is kept disconnected from the load.

2. The method according to claim 1, wherein: When at least one of the inter-pack ring currents between every two battery packs in the battery system is greater than or equal to a preset threshold, it is determined that battery balancing of the battery system is required, and when the maximum of the inter-pack ring currents between every two battery packs in the battery system is less than the preset threshold, it is determined that battery balancing of the battery system is not required.

3. The method according to claim 2, wherein: Actively balancing the battery system during the static phase includes: Active balancing is performed between at least the battery packs of the two battery branches corresponding to the maximum inter-pack ring current.

4. The method according to claim 3, wherein: Active balancing is performed between the battery packs of the two battery branches corresponding to the maximum inter-pack ring current, including: Electricity is transferred between the battery packs of the two battery branches through an inter-pack energy storage device arranged between the two battery branches.

5. The method according to any one of claims 1 to 4, wherein: In the rest phase, the battery system is actively balanced until an active balancing target is reached or until the active balancing lasts for a preset time, and then the battery system is placed in the offline phase.

6. The method according to claim 5, wherein: The active balancing target is that after the active balancing, the inter-pack loop current between every two battery packs in the battery system is less than the preset threshold; and / or The preset duration is greater than or equal to 1 hour and less than or equal to 2 hours.

7. The method according to claim 5 or 6, wherein: When the battery system is actively balanced in the static stage, if the active balancing target is not reached after the active balancing lasts for the preset time, the battery system is placed in the offline stage and the battery system is passively balanced in the offline stage.

8. The method according to claim 7, wherein: When the active balancing has not reached the active balancing target after the preset time period, the passive balancing target is determined before entering the offline stage, in the following manner: Calculate the single pack capacity of each battery pack; Calculate the average capacity based on the single pack capacity of each battery pack; as well as Determine whether the battery pack needs to be passively balanced and the corresponding passive balancing time based on the difference between the single pack capacity of each battery pack and the average capacity, wherein the passive balancing target includes whether each battery pack needs to be passively balanced and the corresponding passive balancing time; Then, in the offline phase, the battery pack that needs to be passively balanced is discharged until the corresponding passive balancing time is reached.

9. The method according to claim 8, wherein: The single pack capacity of each battery pack is calculated based on the OCV-SOC curve and the table lookup method.

10. A battery system, the battery system is used to be connected to a load to supply power to the load, the battery system comprises a plurality of battery branches connected in parallel and a main controller, each battery branch comprises a battery pack and a slave controller for controlling the battery pack, each battery pack comprises a plurality of single cells, and the slave controller of each battery branch is communicatively connected to the main controller; in, The main controller is configured to: After stopping charging or discharging, placing the battery system in a rest stage, in which the battery system is disconnected from the load, so that the multiple parallel battery branches remain connected to each other and both the master controller and the slave controller remain powered on; In the static stage, judging whether it is necessary to perform battery balancing on the battery system according to the inter-pack ring current between every two battery packs in the battery system; When it is determined that the battery system needs to be balanced, actively balancing the battery system in the static stage; as well as When it is determined that battery balancing of the battery system is not required, the battery system is placed in an offline stage. In the offline stage, the multiple parallel battery branches are disconnected from each other, the main controller and the slave controller are placed in a power-off state, and the battery system is kept disconnected from the load.

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