Two-layer battery management system

Abstract

The invention relates to a two-layer battery management system, and belongs to the field of battery management systems. The two-layer battery management system comprises slave control modules correspondingly connected with battery packs, the multiple battery packs can be divided into at least two battery clusters, the slave control modules belonging to the same battery cluster are connected with the same master control module, and the master control module is used for being in communication connection with a vehicle-mounted charger or a charging pile and is further used for being connected with a vehicle-mounted controller; the vehicle-mounted controller is used for determining the priority of the control right of each main control module according to the size of the main control address of each main control module, and switching to the next main control module when the main control module with the control right cannot receive the whole vehicle information sent by the vehicle-mounted controller; the main control module with the control right is used for sending system information of the battery management system to the vehicle-mounted controller, controlling charging and discharging of the corresponding battery cluster and communicating with the vehicle-mounted charger or the charging pile. According to the invention, faults of the two-layer battery management system can be reduced.

Description

Technical Field

[0001] The present invention relates to a two - layer battery management system, belonging to the field of battery management systems. Background Art

[0002] The battery management system integrates the monitoring and management of a battery array to ensure the safe and reliable operation of the battery and keep it running in the best state. Through effective battery management, the service life of the battery can be extended, and at the same time, the battery system can better cooperate with the power generation side, the grid side, and the user side.

[0003] Figure 1 Figure 1 is a schematic structural diagram of an existing three - layer battery management system. As Figure 1 shown, the existing three - layer battery management system includes: a first - level master control module and a plurality of second - level master control modules connected to the first - level master control module. Each second - level master control module is connected to a plurality of first - level slave control modules; each first - level slave control module is used to correspondingly connect a battery pack; the first - level master control module is also respectively connected to a system status light, an on - vehicle charger or a charging pile, and an on - vehicle controller; the on - vehicle power supply is respectively connected to each first - level slave control module, each second - level master control module, and the first - level master control module.

[0004] Among them, each first - level slave control module is used to collect the voltage, perform equalization control, and collect the temperature of the connected battery pack; the communication between each second - level master control module and the first - level slave control modules connected to it is carried out through the internal CAN bus of the second - level master control module, which is used to process the data transmitted by the first - level slave control modules and perform fault judgment, and send the processed data and judgment results to the first - level master control module; the communication between the first - level master control module and each second - level master control module is carried out through the internal CAN bus of the first - level master control module, the charging between the first - level master control module and the charging device is carried out through the CAN bus, the communication between the first - level master control module and the system status light is carried out through the RS485 communication method, and the vehicle - wide control between the first - level master control module and the control device is carried out through the CAN bus.

[0005] As Figure 1The three - layer battery management system shown, on the one hand, since the primary master control module responsible for controlling the operation of the entire system has no replacement or dynamic backup, in special cases (such as abnormal CAN communication or hardware damage of the first - level master control module), the entire battery management system cannot work properly, resulting in a poor user experience; on the second hand, since the first - level master control module and the second - level master control module usually need to be arranged in the high - voltage box, with the continuous improvement of users' requirements for system space and weight, the three - layer battery management system not only increases the layout difficulty of the structure and the weight of the system, but also increases the material cost; on the third hand, since the second - level master control module only responsible for data processing, fault judgment and sending data to the first - level master control module, and all control logics are executed by the first - level master control module, the programs of the first - level master control module and the second - level master control module must be different, resulting in the need for maintenance personnel to view the intranet data of the second - level master control module, the intranet data of the first - level master control and the vehicle - wide network data simultaneously to determine the cause of the fault when a problem occurs, there is a problem of difficult system maintenance.

[0006] The published text of the Chinese invention patent application with the authorization announcement number CN114976320B discloses a battery management method and a battery management system. The method includes: implementing a master control competition strategy for N battery cluster management units to obtain the master control competition result; according to the master control competition result, determining the battery cluster management unit ranked first as the first master control management unit for executing the battery stack management function; if the first master control management unit fails, judging the fault level and executing different fault control strategies according to different fault levels. The above - mentioned battery management method is based on a new - type battery management system with a two - level architecture. During normal operation, the first master control management unit can simultaneously have the functions of battery cluster management and battery stack management. When the first master control management unit fails, it can judge the fault level and execute different fault control strategies to ensure that the battery management system can complete the switch of the master control function more quickly and smoothly, and ensure the performance of the battery management system.

[0007] Although the two - level architecture battery management system has the characteristic of simple structure compared with the three - level architecture battery management system while ensuring the performance of the battery management system remains unchanged, in this solution, since the second master control management can only realize the smooth switch of the battery stack management function by obtaining the master control ability through competition, there is a risk of switch failure, resulting in the battery management system being prone to failure. Summary of the Invention

[0008] The purpose of the present invention is to provide a two - layer battery management system to solve the problem that the two - layer battery management system in the prior art is prone to failure.

[0009] To achieve the above - mentioned purpose, the solution of the present invention includes:

[0010] A two - layer battery management system of the present invention includes slave control modules respectively connected to each battery pack. Multiple battery packs can be divided into at least two battery clusters. Slave control modules belonging to the same battery cluster are connected to the same master control module. The master control module is used for communication connection with an on - vehicle charger or a charging pile; the master control module is also used for connection with an on - vehicle controller;

[0011] The on - vehicle controller is used to determine the priority of control rights of each master control module according to the size of the master control address of each master control module, and switch to the next master control module when the master control module with control rights fails to receive the vehicle information sent by the on - vehicle controller;

[0012] The master control module with control rights is used to send the system information of the battery management system to the on - vehicle controller, control the charge and discharge of the corresponding battery cluster, and communicate with the on - vehicle charger or the charging pile;

[0013] The master control module without control rights is used to receive the control instructions sent by the on - vehicle controller.

[0014] Further, communication between battery clusters is realized among master control modules through a charging CAN bus; the master control module with control rights obtains the status information of other battery clusters through communication between battery clusters.

[0015] Further, the status information of the battery cluster at least includes: the working state of the battery cluster, the execution situation of the power - on process of the battery cluster, the execution situation of the power - off process of the battery cluster, the status of the contactor of the battery cluster, the fault state of the battery cluster, the maximum allowable charge and discharge current of the battery cluster, the heating mode of the battery cluster, and the maximum voltage value of the single battery in the battery cluster.

[0016] Further, the master control module with control rights powers on each battery cluster in the following way:

[0017] After receiving the power - on instruction sent by the on - vehicle controller, when the master control module with control rights determines that there is a situation where the voltage difference between two battery clusters is greater than the preset voltage difference, if in the discharge state, it controls the contactor of the battery cluster with the highest voltage to close, and if in the charging state, it controls the contactor of the battery cluster with the lowest voltage to close.

[0018] Further, after the contactor is closed, the contactors of the offline battery clusters with a voltage difference less than the preset voltage difference from the online battery clusters are closed in sequence;

[0019] Among them, the online battery cluster is the battery cluster with the contactor closed; the offline battery cluster is the battery cluster with the contactor not closed.

[0020] Further, the master control module with control rights powers off each battery cluster in the following way:

[0021] After receiving the power-down instruction sent by the vehicle-mounted controller, the master control module with control rights controls all the contactors of the battery clusters to disconnect;

[0022] When the master control module with control rights does not receive the power-down instruction sent by the vehicle-mounted controller, when it is determined that there is an abnormal battery cluster, the maximum allowable charge and discharge current to the outside is controlled below the first preset current, and then the contactors of the abnormal battery clusters are controlled to disconnect in sequence;

[0023] Among them, the abnormal battery cluster refers to the battery cluster that is full or empty or has a third-level fault; the third-level fault refers to the fault that seriously endangers the battery cluster.

[0024] Further, the master control module with control rights also controls the maximum allowable charge and discharge current to the outside in the following way:

[0025] When the two-layer battery management system includes the liquid heating and liquid cooling function, the maximum allowable charge and discharge current to the outside is: I min *N + I TMS ;

[0026] When the two-layer battery management system does not include the liquid heating and liquid cooling function, the maximum allowable charge and discharge current to the outside is: I min *N;

[0027] Among them, I min represents the minimum charge and discharge current in the online battery clusters; N represents the number of online battery clusters; I TMS represents the rated working current of the liquid cooling and liquid heating equipment; the online battery clusters are the battery clusters with the contactors closed.

[0028] Further, the master control module with control rights corrects the SOC value displayed by the system in the following way:

[0029] Correct the SOC value displayed by the system at the first rate;

[0030] Correcting the SOC value displayed by the system at the first rate includes: when the average SOC value of the battery clusters is less than the first preset SOC value, the first rate is the quotient of the difference between the SOC value displayed by the system and the actual SOC value of the system divided by the first preset time; the actual SOC value of the system is the minimum SOC value in the battery clusters;

[0031] When the average SOC value of the battery clusters is greater than the first preset SOC value but less than the second preset SOC value, the first rate is the quotient of the difference between the SOC value displayed by the system and the actual SOC value of the system divided by the second preset time; the actual SOC value of the system is the average SOC value of the battery clusters,

[0032] When the average SOC value of the battery cluster is greater than the second preset SOC value, the first rate is the quotient of the difference between the SOC value displayed by the system and the actual SOC value of the system divided by the third preset time; the actual SOC value of the system is the maximum SOC value in the battery cluster.

[0033] Furthermore, the main control module with control authority confirms the system fault level in the following manner:

[0034] When only a first-level fault occurs in the faulty battery cluster, the system fault level is determined to be a first-level fault;

[0035] When only a second-level fault occurs in the faulty battery cluster or when there is only one faulty battery cluster and the fault that occurs is a third-level fault, the system fault level is determined to be a second-level fault;

[0036] When there are multiple faulty battery clusters and the faults that occur are third-level faults, the system fault level is determined to be a third-level fault;

[0037] Among them, the severity of the first-level fault is less than that of the second-level fault; the severity of the second-level fault is less than that of the third-level fault.

[0038] Furthermore, the main control module is also communicatively connected to the system status light; the system status light is used to indicate the system fault level.

[0039] The beneficial effects of the present invention are as follows: As an improved invention, a two-layer battery management system provided by the present invention includes slave control modules respectively connected to each battery pack. Multiple battery packs can be at least divided into two battery clusters. Slave control modules belonging to the same battery cluster are connected to the same master control module. The master control module is used for communication connection with an in-vehicle charger or a charging pile, and is also used for connection with an in-vehicle controller. The in-vehicle controller is used to determine the priority of the control right of each master control module according to the size of the master control address of each master control module, and to switch to the next master control module when the master control module with the control right fails to receive the vehicle information sent by the in-vehicle controller. The master control module with the control right is used to send the system information of the battery management system to the in-vehicle controller, control the charging and discharging of the corresponding battery cluster, and communicate with the in-vehicle charger or the charging pile. The master control module without the control right is used to receive the control instructions sent by the in-vehicle controller. Compared with the technical solution of the existing two-level battery management system, since the control right of the master control module is determined by the in-vehicle controller according to the size of the master control address of the master control module, rather than the master control module competing for the control right by itself, the occurrence of competition failure can be reduced, and thus the occurrence of faults in the two-layer battery management system can be reduced. On the other hand, the switching of the control right is also controlled by the in-vehicle controller, and there is no risk of switching failure. Therefore, the occurrence of faults in the two-layer battery management system can be further reduced. Thirdly, compared with the solution of the three-layer battery management system, the two-layer battery management system solution provided by the present invention has a simple structure, can reduce costs, reduce the overall weight and volume of the system, and is more conducive to maintenance personnel to conduct fault troubleshooting or update and upgrade. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of an existing three-layer battery management system;

[0041] Figure 2 is a schematic structural diagram of a two-layer battery management system provided by an embodiment of the present invention;

[0042] Figure 3 is a schematic flow diagram of a power-on logic provided by an embodiment of the present invention;

[0043] Figure 4 is a schematic flow diagram of a power-off logic provided by an embodiment of the present invention;

[0044] Figure 5 is a schematic flow diagram of the maximum allowable discharge current to the outside provided by an embodiment of the present invention;

[0045] Figure 6 is a schematic flow diagram of the calculation logic of the system display SOC provided by an embodiment of the present invention;

[0046] Figure 7 It is a schematic structural diagram of communication between battery clusters provided by an embodiment of the present invention. Specific Embodiment

[0047] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0048] The concept of the present invention lies in: realizing the functions of a three-layer battery management system through a two-layer battery management system.

[0049] Specifically: A two-layer battery management system includes a slave control module corresponding to each battery pack. Multiple battery packs can be at least divided into two battery clusters. The slave control modules belonging to the same battery cluster are connected to the same master control module. The master control module is used for communication connection with an on-vehicle charger or a charging pile, and is also used for connection with an on-vehicle controller; the on-vehicle controller is used for determining the priority of control rights of each master control module according to the size of the master control address of each master control module, and switching to the next master control module when the master control module with control rights fails to receive the vehicle information sent by the on-vehicle controller; the master control module with control rights is used for sending the system information of the battery management system to the on-vehicle controller, controlling the charging and discharging of the corresponding battery cluster, and communicating with the on-vehicle charger or the charging pile, and the master control module without control rights is used for receiving the control instructions sent by the on-vehicle controller.

[0050] An embodiment of a two-layer battery management system:

[0051] Figure 2 It is a schematic structural diagram of a two-layer battery management system provided by an embodiment of the present invention, as Figure 2 shown. The two-layer battery management system includes a slave control module corresponding to each battery pack. Multiple battery packs can be at least divided into two battery clusters. The slave control modules belonging to the same battery cluster are connected to the same master control module. Each master control module is used for communication connection with an on-vehicle charger or a charging pile; the master control module is also used for connection with an on-vehicle controller; the on-vehicle controller is used for determining the priority of control rights of each master control module according to the size of the master control address of each master control module, and switching to the next master control module when the master control module with control rights fails to receive the vehicle information sent by the on-vehicle controller; the master control module with control rights is used for sending the system information of the battery management system to the on-vehicle controller, controlling the charging and discharging of the corresponding battery cluster, and communicating with the on-vehicle charger or the charging pile; the master control module without control rights is used for receiving the control instructions sent by the on-vehicle controller.

[0052] To reduce the volume of the two-layer battery management system, as an optional embodiment, the on-vehicle power supply provides working voltages to each slave control module and each master control module respectively through power supply lines.

[0053] For the convenience of maintenance personnel to know the system fault level, as an optional implementation manner, each main control module is also communicatively connected to a system status light, and the system status light is used to indicate the system fault level.

[0054] Among them, the system fault levels are divided into first-level faults, second-level faults, and third-level faults; the severity of first-level faults is less than that of second-level faults; the severity of second-level faults is less than that of the third-level faults.

[0055] Among them, the communication method between each main control module and the system status light can be RS485 communication, or RS232 communication, etc. The present invention does not make a special limitation on this. In the following embodiments, the communication method between each main control module and the system status light is RS485 communication as an example for exemplary illustration.

[0056] Among them, each slave control module is used for voltage acquisition, equalization control, temperature acquisition, etc. of the connected battery pack. The present invention does not make a special limitation on this.

[0057] Among them, each main control module communicates with each slave control module connected to it through the CAN bus inside the main control module; each main control module communicates with the on-vehicle charger or charging pile through the charging CAN bus; each main control module communicates with the on-vehicle controller through the vehicle CAN bus.

[0058] Among them, the on-vehicle controller may include a vehicle control unit (VCU), a thermal management system (TMS), a power domain controller, etc. The present invention does not make a special limitation on this.

[0059] Among them, each main control module realizes communication between battery clusters through the charging CAN bus; the main control module with control rights obtains the status information of other battery clusters through the communication between battery clusters.

[0060] This embodiment takes two battery clusters as an example for exemplary illustration. Therefore, there are two main control modules, and each battery cluster includes multiple series-connected battery packs. For those skilled in the art, when knowing the connection relationship between each electrical appliance in the two-layer battery management system of two battery clusters, the connection relationship between each electrical appliance in the two-layer battery management system of three or more battery clusters can be envisioned, and will not be elaborated here.

[0061] The following combines Figure 7 to introduce the communication between battery clusters in detail.

[0062] Figure 7It is a schematic structural diagram of communication between battery clusters provided by an embodiment of the present invention. As Figure 7 shown, the vehicle-mounted controller sends vehicle information and control instructions to each main control module. Each main control module obtains the status information of its corresponding battery cluster and the status information of other battery clusters through the charging CAN bus. Taking the main control module 1 as the main control module with control rights as an example, the main control module 1 sends the system information of the battery management system to the vehicle-mounted controller, the vehicle-mounted charger, and the charging pile, and the remaining main control modules only receive the control instructions sent by the vehicle-mounted controller.

[0063] Among them, the status information of the battery cluster at least includes: the working status of the battery cluster, the execution situation of the power-on process of the battery cluster, the execution situation of the power-off process of the battery cluster, the status of the contactor of the battery cluster, the fault status of the battery cluster, the maximum allowable charge and discharge current of the battery cluster, the heating mode of the battery cluster, and the maximum voltage value of the single battery in the battery cluster.

[0064] Among them, the system information of the battery management system includes: power-on logic, power-off logic, the maximum allowable charge and discharge current to the outside, the correction logic for correcting the SOC displayed by the system, and the determination of the system fault level.

[0065] Next, in combination with Figure 3 the power-on logic will be introduced in detail.

[0066] Figure 3 It is a schematic flowchart of a power-on logic provided by an embodiment of the present invention. As Figure 3 shown, this power-on logic includes the following steps S301 to S304.

[0067] S301. After receiving the power-on instruction sent by the vehicle-mounted controller, the main control module with control rights determines whether there is a situation where the voltage difference between two battery clusters is greater than the preset voltage difference. If not, step S302 is executed; if so, step S303 is executed.

[0068] Among them, the voltage difference between two battery clusters is the voltage difference between any two battery clusters, which can be the voltage difference between two adjacent battery clusters or the voltage difference between two non-adjacent battery clusters, etc. The present invention does not make special limitations on this.

[0069] Among them, the preset voltage difference can be 5 volts (V), or 4V, or 6V, etc., and can be set according to actual needs. The present invention does not make special limitations on this. Subsequently, taking the preset voltage difference in step S301 as 5V as an example, an exemplary description will be given.

[0070] Among them, if there is a situation where the voltage difference between two battery clusters is greater than the preset voltage difference, it indicates that there is a voltage imbalance between the battery clusters. If the voltage difference between the battery clusters is too large, it will cause a circulating current phenomenon in the system, and further lead to the risk of overcharging of single cells. Therefore, in order to protect single cells, when there is a voltage imbalance, a cluster combination operation needs to be performed, that is, step S303 is executed; if there is no situation where the voltage difference between two battery clusters is greater than the preset voltage difference, it means that the voltage differences between all battery clusters are less than or equal to the preset voltage difference, and no cluster combination operation is required, that is, step S302 is executed.

[0071] Among them, when the voltage difference between two battery clusters is equal to the preset voltage difference, either step S302 or step S303 can be executed. The present invention does not make a special limitation on this. In order to ensure that the circulating current phenomenon does not occur, in the embodiments of the present invention, when the voltage difference between two battery clusters is equal to the preset voltage difference, taking the execution of step S303 as an example, an exemplary description is given.

[0072] S302. The main control module with control authority controls all the contactors of the battery clusters to close.

[0073] Among them, after the main control module with control authority controls all the contactors of the battery clusters to close, all the battery clusters are in a discharging or charging state, and the voltage differences between the battery clusters are in an equilibrium state.

[0074] S303. Determine whether the system is in a discharging state or a charging state. If the system is in a discharging state, control the contactor of the battery cluster with the highest voltage to close; if the system is in a charging state, control the contactor of the battery cluster with the lowest voltage to close.

[0075] Among them, when the system is in a discharging state, closing the contactor of the battery cluster with the highest voltage first can allow the battery cluster with the highest voltage to discharge first. As time goes by, the voltage of the battery cluster with the highest voltage will gradually decrease, making the voltage differences between the battery clusters in an equilibrium state.

[0076] Among them, when the system is in a charging state, closing the contactor of the battery cluster with the lowest voltage first can allow the battery cluster with the lowest voltage to charge first. As time goes by, the voltage of the battery cluster with the lowest voltage will gradually increase, making the voltage differences between the battery clusters in an equilibrium state.

[0077] In order to make the equilibrium state between the battery clusters more persistent, as an optional implementation manner, after step S303 is executed, step S304 can be executed.

[0078] S304. Close the contactors of the offline battery clusters whose voltage differences from the online battery clusters are less than the preset voltage difference in sequence.

[0079] Among them, the online battery cluster is the battery cluster with the contactor closed; the offline battery cluster is the battery cluster with the contactor not closed.

[0080] Specifically, successively closing the contactors of the offline battery clusters whose voltage difference from the online battery clusters is less than the preset voltage difference includes the following steps S304A and S304B.

[0081] S304A. Determine whether the absolute value of the difference between the voltage of the offline battery cluster and the voltage of the online battery cluster is less than the preset voltage. If it is less, close the contactor of this offline battery cluster, and then continue to execute step S304B; if it is greater than or equal to, continue to execute step S304A.

[0082] Among them, the preset voltage in step S304 can be the same as or different from the preset voltage in step S301. The present invention does not make a special limitation on this. In this embodiment, the same is taken as an example for illustrative purposes. Exemplarily, the preset voltage in step S304 is 5V.

[0083] S304B. Determine whether there is an offline battery cluster. If there is, continue to execute step S304A; if not, it means that the contactors of all battery clusters are closed, that is, the parallel connection operation is completed and the system is powered on.

[0084] Next, in combination with Figure 4 the power-off logic will be introduced in detail.

[0085] Figure 4 is a schematic flowchart of a power-off logic provided by an embodiment of the present invention. As Figure 4 shown, this power-off logic includes the following steps S401 to S402.

[0086] S401. After receiving the power-off instruction sent by the vehicle-mounted controller, the main control module with control authority controls all the contactors of the battery clusters to disconnect.

[0087] S402. When the main control module with control authority does not receive the power-off instruction sent by the vehicle-mounted controller, determine whether there is an abnormal battery cluster. If there is, control the maximum allowable charge and discharge current to be below the first preset current, and then successively control the contactors of the abnormal battery clusters to disconnect;

[0088] Among them, the abnormal battery cluster means the battery cluster that is full or empty or has a third-level fault; the third-level fault means a fault that seriously endangers the battery cluster.

[0089] Among them, controlling the maximum allowable charge and discharge current to be below the first preset current and then successively controlling the contactors of the abnormal battery clusters to disconnect can avoid damage to the contactors caused by cutting off the load.

[0090] Among them, determining whether there is an abnormal battery cluster includes the following steps S402A and S402B.

[0091] S402A. Determine whether there is a fully charged or discharged battery cluster. If so, control the maximum allowable charge and discharge current to be below the first preset current; if not, execute step S402B.

[0092] Among them, the number of fully charged or discharged battery clusters can be one, two, three or more, etc. The present invention does not make special limitations on this.

[0093] S402B. Determine whether there is a battery cluster with a level 3 fault. If so, control the maximum allowable charge and discharge current to be below the first preset current; if not, continue to execute step S402A.

[0094] Among them, the number of battery clusters with a level 3 fault can be one, two, three or more, etc. The present invention does not make special limitations on this.

[0095] Among them, the first preset current is related to the specified current I and the total number n of battery clusters. Specifically, the first preset current is equal to the product of the specified current I and the total number n of battery clusters. Among them, the specified current I can be adjusted according to actual needs. The present invention does not make special limitations on this.

[0096] Among them, steps S402A and S402B can be interchanged, that is, first determine whether there is a battery cluster with a level 3 fault and then determine whether there is a fully charged or discharged battery cluster. The present invention does not make special limitations on the execution order of steps S402A and S402B.

[0097] Among them, sequentially controlling the contactors of abnormal battery clusters to disconnect includes the following steps S402C and S402D.

[0098] S402C. Disconnect the contactor of the battery cluster that meets the conditions.

[0099] Among them, the battery cluster that meets the conditions refers to the battery cluster that is fully charged or discharged or has a level 3 fault; disconnecting the contactor of the battery cluster that meets the conditions is equivalent to performing a cluster removal operation.

[0100] S402D. Determine whether there are still online battery clusters. If so, continue to execute step S402A; if not, complete system power-off.

[0101] Among them, if there are still online battery clusters, it is necessary to determine whether there are any abnormalities in the online battery clusters. If there are abnormalities, the contactors of the abnormal battery clusters are disconnected, and finally the contactors of all the online battery clusters are disconnected to power off the system.

[0102] The following combines Figure 5 to introduce the maximum allowable charge and discharge current in detail.

[0103] Figure 5 is a schematic flow chart of the maximum allowable discharge current to the outside provided by an embodiment of the present invention. As Figure 5 shown, the main control module with control authority controls the maximum allowable charge and discharge current to the outside, including the following steps S501.

[0104] S501. Determine whether there is a liquid heating and liquid cooling function. If there is, determine the maximum allowable charge and discharge current to the outside according to formula (1); if not, determine the maximum allowable charge and discharge current to the outside according to formula (2).

[0105] Among them, when the system has a liquid heating and liquid cooling function, a part of the battery cluster charge and discharge current is provided to the liquid heating and liquid cooling equipment for the liquid heating and liquid cooling equipment to work, and the other part is displayed externally. Therefore, when there is a liquid heating and liquid cooling function, the maximum allowable charging current to the outside needs to include the true charge and discharge current of the battery cluster and the current flowing through the liquid heating and liquid cooling equipment. Therefore, the maximum allowable charge and discharge current to the outside can be determined according to formula (1).

[0106] Among them, when the system does not have a liquid heating and liquid cooling function, the battery cluster charge and discharge current is all displayed externally. Therefore, the maximum allowable charge and discharge current to the outside can be determined according to formula (2).

[0107] I 充放MAX =I min *N + I TMS (1)

[0108] I 充放MAX =I min *N (2)

[0109] Among them, I min represents the minimum charge and discharge current in the online battery cluster; N represents the number of online battery clusters; I TMS represents the rated working current of the liquid cooling and liquid heating equipment.

[0110] The following combines Figure 6 to introduce in detail the process of the main control module with control authority correcting the SOC value displayed by the system.

[0111] Figure 6 is a schematic flow chart of the calculation logic of the SOC displayed by the system provided by an embodiment of the present invention. As Figure 6As shown, the master control module with control rights corrects the SOC value displayed by the system through the following steps S601 and S602.

[0112] The master control module with control rights corrects the SOC value displayed by the system at a first rate.

[0113] Among them, the first rate is related to the actual SOC value of the system, the SOC value displayed by the system, and a preset time, that is, the first rate = (the SOC value displayed by the system - the actual SOC value of the system) / preset time. Among them, the preset time can be divided into a first preset time, a second preset time, and a third preset time according to different situations; the first preset time, the second preset time, and the third preset time can be the same or different, and the present invention does not make special limitations on this. Subsequently, taking the first preset time and the third preset time as the same as an example, an exemplary description will be given.

[0114] Among them, the actual SOC value of the system is also related to the magnitude of the average SOC value of the battery cluster. Different average SOC values of the battery cluster result in different actual SOC values of the system.

[0115] Among them, the battery management system includes n battery clusters, each battery cluster has an SOC value, and the average SOC value of the battery cluster is obtained by adding the SOC values of the n battery clusters and then dividing by the total number n of the battery clusters.

[0116] Specifically, in S601, it is judged whether the average SOC value of the battery cluster is less than the first preset SOC value. If it is less, the actual SOC value of the system is made equal to the minimum SOC value in the battery cluster; if it is greater than or equal to, step S602 is executed.

[0117] Among them, the battery management system includes n battery clusters, each battery cluster has an SOC value, and the battery cluster corresponding to the minimum SOC value is selected as the minimum SOC value in the battery cluster.

[0118] When the average SOC value of the battery cluster is less than the first preset SOC value, the first rate = (the SOC value displayed by the system - the minimum SOC value in the battery cluster) / the first preset time.

[0119] In S602, it is judged whether the average SOC value of the battery cluster is greater than the second preset SOC value. If it is greater, the actual SOC value of the system is made equal to the maximum SOC value in the battery cluster; if it is less than or equal to, the actual SOC value of the system is made equal to the average SOC value of the battery cluster.

[0120] Among them, the battery management system includes n battery clusters, each battery cluster has an SOC value, and the battery cluster corresponding to the maximum SOC value is selected as the maximum SOC value in the battery cluster.

[0121] When the average SOC value of the battery cluster is greater than the second preset SOC value, the first rate = (the SOC value displayed by the system - the maximum SOC value in the battery cluster) / the third preset time.

[0122] When the average SOC value of the battery cluster is less than or equal to the second preset SOC value, or greater than or equal to the first preset SOC value, the first rate = (the SOC value displayed by the system - the average SOC value of the battery cluster) / the second preset time.

[0123] Among them, for the duration settings of the first preset time, the second preset time, and the third preset time, the present invention does not make special limitations. Exemplarily, both the first preset time and the third preset time are 1 minute (min), and the second preset time is 3 min.

[0124] Among them, the first preset SOC value is less than the second preset SOC value; for the first preset SOC value and the second preset SOC value, the present invention does not make special limitations. Exemplarily, the first preset SOC value can be 15%, and the second preset SOC value can be 90%.

[0125] When correcting the SOC value displayed by the system at the first rate, in the case of a discharging state, if the first rate is negative, no correction is performed; in the case of a charging state, if the first rate is positive, no correction is performed. That is, during discharging, the SOC value displayed by the system cannot increase, and during charging, the SOC value displayed by the system cannot decrease. When there are still online battery clusters, in the case of a discharging state, the minimum SOC value displayed by the system is 1%, and in the case of a charging state, the maximum SOC value displayed by the system is 99%.

[0126] Correcting the SOC value displayed by the system at the first rate can make the SOC value displayed by the system change smoothly, be closer to the real SOC value, there is no jump phenomenon, and the customer satisfaction is improved.

[0127] The confirmation of the system fault level is determined by the main control module with control authority. The following details the specific process of the main control module with control authority for confirming the system fault level.

[0128] When only a first-level fault occurs in the faulty battery cluster, it is determined that the system fault level is a first-level fault. Specifically, among all the battery clusters, if only one battery cluster has a first-level fault and the rest of the battery clusters have no faults, then at this time, it is determined that the system fault level is a first-level fault; or, among all the battery clusters, if multiple battery clusters have faults, but the fault types of the faulty battery clusters are all first-level faults, then at this time, it is determined that the system fault level is a first-level fault.

[0129] When the faulty battery cluster only has a secondary fault or when there is only one faulty battery cluster and the fault that occurs is a tertiary fault, the system fault level is determined to be a secondary fault. Specifically, among all the battery clusters, if only one battery cluster has a secondary fault and the rest of the battery clusters have no faults, then at this time, the system fault level is determined to be a secondary fault; or, among all the battery clusters, if multiple battery clusters have faults, but the fault types of the faulty battery clusters are all secondary faults, then at this time, the system fault level is determined to be a secondary fault; or, among all the battery clusters, if only one battery cluster has a tertiary fault and the rest of the battery clusters have no faults, then at this time, the system fault level is determined to be a secondary fault.

[0130] When there are multiple faulty battery clusters and the faults that occur are tertiary faults, the system fault level is determined to be a tertiary fault. Specifically, among all the battery clusters, if multiple battery clusters have faults, but the fault types of the faulty battery clusters are all tertiary faults, then at this time, the system fault level is determined to be a tertiary fault.

[0131] Among them, the color of the system status indicator corresponding to the system fault level is not particularly limited in the present invention. Exemplarily, when the system fault level is a primary fault, the system status indicator is displayed in yellow; when the system fault level is a secondary fault, the system status indicator is displayed in light red; when the system fault level is a tertiary fault, the system status indicator is displayed in dark red.

[0132] A two - layer battery management system provided by an embodiment of the present invention includes slave control modules respectively connected to each battery pack. Multiple battery packs can be divided into at least two battery clusters. Slave control modules belonging to the same battery cluster are connected to the same master control module. The master control module is used for communicating with an on - vehicle charger or a charging pile, and is also used for connecting to an on - vehicle controller. The on - vehicle controller is used for determining the priority of the control right of each master control module according to the size of the master address of each master control module, and for switching to the next master control module when the master control module with the control right fails to receive the vehicle - wide information sent by the on - vehicle controller. The master control module with the control right is used for sending the system information of the battery management system to the on - vehicle controller, controlling the charging and discharging of the corresponding battery cluster, and communicating with the on - vehicle charger or the charging pile. The master control module without the control right is used for receiving the control instructions sent by the on - vehicle controller. Compared with the technical solutions of the existing two - level battery management system, in the two - layer battery management system provided by the embodiment of the present invention, since the control right of the master control module is determined by the on - vehicle controller according to the size of the master address of the master control module, rather than the master control module competing for the control right by itself, the occurrence of situations of competition failure can be reduced, and thus the occurrence of faults in the two - layer battery management system can be reduced. On the other hand, the switching of the control right is also controlled by the on - vehicle controller, and there is no risk of switching failure. Therefore, the occurrence of faults in the two - layer battery management system can be further reduced. Thirdly, compared with the solution of the three - layer battery management system, the two - layer battery management system solution provided by the embodiment of the present invention has a simple structure, can reduce costs, reduce the overall weight and volume of the system, and is more conducive to maintenance personnel to conduct fault troubleshooting or update and upgrade.

Claims

1. A two-layer battery management system, comprising a slave control module connected to each battery pack, wherein the multiple battery packs can be divided into at least two battery clusters, and the slave control modules belonging to the same battery cluster are connected to the same master control module, characterized in that: The main control module is used to communicate with the vehicle charger or charging pile; the main control module is also used to connect with the vehicle controller; The vehicle-mounted controller is used to determine the priority of each of the master control modules according to the size of the master control address of each of the master control modules, and to switch to the next master control module when the master control module with control right cannot receive the vehicle information sent by the vehicle-mounted controller; The master control module with control authority is used to send system information of the battery management system to the vehicle controller, control the charging and discharging of the corresponding battery cluster, and communicate with the vehicle charger or charging pile; The main control module that does not have control rights is used to receive control instructions sent by the vehicle-mounted controller.

2. The two-layer battery management system according to claim 1, characterized in that: The master control modules communicate with each other through the charging CAN bus; the master control module with control authority obtains the status information of other battery clusters through the communication between battery clusters.

3. The two-layer battery management system according to claim 2, characterized in that: The status information of the battery cluster includes at least: the working status of the battery cluster, the execution status of the power-on process of the battery cluster, the execution status of the power-off process of the battery cluster, the status of the contactor of the battery cluster, the fault status of the battery cluster, the maximum allowable charge and discharge current of the battery cluster, the heating mode of the battery cluster and the maximum voltage value of the single cells in the battery cluster.

4. The two-layer battery management system according to claim 3, characterized in that: The master control module with control power supplies each battery cluster in the following manner: After receiving the power-on command sent by the vehicle controller, the main control module with control authority, when determining that the voltage difference between the two battery clusters is greater than the preset voltage difference, if it is in a discharging state, controls the contactor of the battery cluster with the largest voltage to close; if it is in a charging state, controls the contactor of the battery cluster with the smallest voltage to close.

5. The two-layer battery management system according to claim 4, characterized in that: After the contactor is closed, the contactors of the off-line battery clusters whose voltage difference with the on-line battery cluster is less than a preset voltage difference are closed in sequence; The online battery cluster is a battery cluster with a closed contactor; and the offline battery cluster is a battery cluster with an unclosed contactor.

6. The two-layer battery management system according to claim 3, characterized in that: The master control module with control authority powers down each battery cluster in the following manner: After receiving the power-off instruction sent by the vehicle controller, the main control module with control authority controls the contactors of all battery clusters to be disconnected; When the main control module with control authority does not receive the power-off instruction sent by the vehicle controller, when it is determined that there is an abnormal battery cluster, it controls the maximum allowable external charge and discharge current to be below the first preset current, and then controls the contactors of the abnormal battery cluster to be disconnected in turn; The abnormal battery cluster refers to a battery cluster that is fully charged or discharged or has a third-level fault; the third-level fault refers to a fault that is seriously harmful to the battery cluster.

7. The two-layer battery management system according to claim 3, characterized in that: The master control module with control rights also controls the maximum allowable external charging and discharging current in the following manner: When the two-layer battery management system includes liquid heating and liquid cooling functions, the maximum allowable external charging and discharging current is: I min *N+I TMS ; When the two-layer battery management system does not include the liquid heating and liquid cooling function, the maximum allowable external charging and discharging current is: I min *N; Among them, I min Indicates the minimum charge and discharge current in the online battery cluster; N indicates the number of online battery clusters; I TMS Indicates the rated operating current of the liquid-cooled and liquid-heated equipment; the online battery cluster is a battery cluster with closed contactors.

8. The two-layer battery management system according to claim 3, characterized in that: The main control module with control right corrects the SOC value displayed by the system in the following way: Correcting the SOC value displayed by the system at a first rate; The first rate of correcting the SOC value displayed by the system includes: when the average SOC value of the battery cluster is less than a first preset SOC value, the first rate is the quotient of the SOC value displayed by the system minus the actual SOC value of the system and the first preset time; the actual SOC value of the system is the minimum SOC value in the battery cluster; When the average SOC value of the battery cluster is greater than the first preset SOC value but less than the second preset SOC value, the first rate is the quotient of the SOC value displayed by the system minus the actual SOC value of the system and the second preset time; the actual SOC value of the system is the average SOC value of the battery cluster, When the average SOC value of the battery cluster is greater than the second preset SOC value, the first rate is the quotient of the SOC value displayed by the system minus the actual SOC value of the system and the third preset time; the actual SOC value of the system is the maximum SOC value in the battery cluster.

9. The two-layer battery management system according to claim 3, characterized in that: The master control module with control authority confirms the system fault level in the following way: When the faulty battery cluster only has a primary fault, the system fault level is determined to be a primary fault; When the faulty battery cluster has only a level 2 fault or when there is only one faulty battery cluster and the fault is a level 3 fault, the system fault level is determined to be a level 2 fault; When there are multiple faulty battery clusters and the fault is a level 3 fault, the system fault level is determined to be a level 3 fault; Wherein, the severity of the primary fault is less than the severity of the secondary fault; The severity of the secondary fault is less than the severity of the tertiary fault.

10. The two-layer battery management system according to claim 9, characterized in that: The main control module is also communicatively connected to a system status light; the system status light is used to indicate the system fault level.

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